* [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation
@ 2025-06-26 23:54 Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 01/64] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text Josh Poimboeuf
` (63 more replies)
0 siblings, 64 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
This series introduces new objtool features and a klp-build script to
generate livepatch modules using a source .patch as input.
This builds on concepts from the longstanding out-of-tree kpatch [1]
project which began in 2012 and has been used for many years to generate
livepatch modules for production kernels. However, this is a complete
rewrite which incorporates hard-earned lessons from 12+ years of
maintaining kpatch.
Key improvements compared to kpatch-build:
- Integrated with objtool: Leverages objtool's existing control-flow
graph analysis to help detect changed functions.
- Works on vmlinux.o: Supports late-linked objects, making it
compatible with LTO, IBT, and similar.
- Simplified code base: ~3k fewer lines of code.
- Upstream: No more out-of-tree #ifdef hacks, far less cruft.
- Cleaner internals: Vastly simplified logic for symbol/section/reloc
inclusion and special section extraction.
- Robust __LINE__ macro handling: Avoids false positive binary diffs
caused by the __LINE__ macro by introducing a fix-patch-lines script
which injects #line directives into the source .patch to preserve
the original line numbers at compile time.
The primary user interface is the klp-build script which does the
following:
- Builds an original kernel with -function-sections and
-fdata-sections, plus objtool function checksumming.
- Applies the .patch file and rebuilds the kernel using the same
options.
- Runs 'objtool klp diff' to detect changed functions and generate
intermediate binary diff objects.
- Builds a kernel module which links the diff objects with some
livepatch module init code (scripts/livepatch/init.c).
- Finalizes the livepatch module (aka work around linker wreckage)
using 'objtool klp post-link'.
I've tested with a variety of patches on defconfig and Fedora-config
kernels with both GCC and Clang.
These patches can also be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git klp-build-v3
Please test!
[1] https://github.com/dynup/kpatch
Changes since v2: https://lore.kernel.org/cover.1725334260.git.jpoimboe@kernel.org
- Fix bisection issue (Joe)
- Add CONFIG_KLP_BUILD to prevent powerpc from doing objtool-on-vmlinux (Joe)
- Use arch_pc_relative_reloc() in arch_insn_adjusted_addend() (Peter)
- Drop "objtool: Suppress section skipping warnings with --dryrun" (Peter)
- Resurrect --backup (Peter)
- Remove 16 byte prefix assumption (Peter, robot)
- Bump SEC_NAME_LEN to 1024 (Peter)
- Add sprintf error checking (Peter)
- Fix brace usage (Peter)
- Improve buggy linker sh_entsize warning (Peter)
- Refactor add_jump_destinations() some more to work with ITS retpolines
- Simplify error handling boilerplate
- Run "make clean" before original kernel build
- Fix .cmd file copying for CONFIG_MODVERSIONS (Joe)
- Add a line to setlocalversion rather than replacing the whole file
- Fix unset 'found' variable (Joe)
- Define section entry struct sizes in asm-offset.c and bounds.c (Brian)
- Fix STACK_FRAME_NON_STANDARD entry size unification (robot)
- Check for .rodata.*, .bss.* (Joe)
- Copy import_ns= entries from .modinfo (Joe)
- Strip signature from 'git format-patch' patches (Joe)
- Fix add_jump_destinations() (robot)
- ARCH=um fixes (robot)
- Fix vmlinux.o/vmlinux sympos mismatch
- Add klp-build --jobs option
- Allow .git to be a file (Dylan)
- Static branch/call fixes (Joe)
- Disable .printk_index support for now (Joe)
- Strip .BTF section (Joe)
Josh Poimboeuf (64):
s390/vmlinux.lds.S: Prevent thunk functions from getting placed with
normal text
vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros
x86/module: Improve relocation error messages
x86/kprobes: Remove STACK_FRAME_NON_STANDARD annotation
compiler: Tweak __UNIQUE_ID() naming
compiler.h: Make addressable symbols less of an eyesore
elfnote: Change ELFNOTE() to use __UNIQUE_ID()
kbuild: Remove 'kmod_' prefix from __KBUILD_MODNAME
modpost: Ignore unresolved section bounds symbols
x86/alternative: Refactor INT3 call emulation selftest
objtool: Make find_symbol_containing() less arbitrary
objtool: Fix broken error handling in read_symbols()
objtool: Propagate elf_truncate_section() error in elf_write()
objtool: Remove error handling boilerplate
objtool: Add empty symbols to the symbol tree again
objtool: Fix interval tree insertion for zero-length symbols
objtool: Fix weak symbol detection
objtool: Fix x86 addend calculation
objtool: Fix __pa_symbol() relocation handling
objtool: Fix "unexpected end of section" warning for alternatives
objtool: Check for missing annotation entries in read_annotate()
objtool: Const string cleanup
objtool: Clean up compiler flag usage
objtool: Remove .parainstructions reference
objtool: Convert elf iterator macros to use 'struct elf'
objtool: Add section/symbol type helpers
objtool: Mark .cold subfunctions
objtool: Fix weak symbol hole detection for .cold functions
objtool: Mark prefix functions
objtool: Simplify reloc offset calculation in unwind_read_hints()
objtool: Avoid emptying lists for duplicate sections
objtool: Rename --Werror to --werror
objtool: Resurrect --backup option
objtool: Reindent check_options[]
objtool: Refactor add_jump_destinations()
objtool: Simplify special symbol handling in elf_update_symbol()
objtool: Generalize elf_create_symbol()
objtool: Generalize elf_create_section()
objtool: Add elf_create_data()
objtool: Add elf_create_reloc() and elf_init_reloc()
objtool: Add elf_create_file()
kbuild,x86: Fix special section module permissions
x86/alternative: Define ELF section entry size for alternatives
x86/jump_label: Define ELF section entry size for jump labels
x86/static_call: Define ELF section entry size of static calls
x86/extable: Define ELF section entry size for exception table
x86/bug: Define ELF section entry size for bug table
x86/orc: Define ELF section entry size for unwind hints
objtool: Unify STACK_FRAME_NON_STANDARD entry sizes
objtool/klp: Add --checksum option to generate per-function checksums
objtool/klp: Add --debug-checksum=<funcs> to show per-instruction
checksums
objtool/klp: Introduce klp diff subcommand for diffing object files
objtool/klp: Add --debug option to show cloning decisions
objtool/klp: Add post-link subcommand to finalize livepatch modules
objtool: Disallow duplicate prefix symbols
objtool: Add base objtool support for livepatch modules
livepatch: Add CONFIG_KLP_BUILD
kbuild,objtool: Defer objtool validation step for CONFIG_KLP_BUILD
livepatch/klp-build: Introduce fix-patch-lines script to avoid
__LINE__ diff noise
livepatch/klp-build: Add stub init code for livepatch modules
livepatch/klp-build: Introduce klp-build script for generating
livepatch modules
livepatch/klp-build: Add --debug option to show cloning decisions
livepatch/klp-build: Add --show-first-changed option to show function
divergence
livepatch: Introduce source code helpers for livepatch modules
MAINTAINERS | 3 +-
arch/Kconfig | 3 +
arch/s390/include/asm/nospec-insn.h | 2 +-
arch/s390/kernel/vmlinux.lds.S | 2 +-
arch/um/include/asm/Kbuild | 1 -
arch/um/include/shared/common-offsets.h | 3 +
arch/x86/Kconfig | 2 +
arch/x86/include/asm/alternative.h | 5 +-
arch/x86/include/asm/asm.h | 22 +-
arch/x86/include/asm/bug.h | 45 +-
arch/x86/include/asm/jump_label.h | 17 +-
arch/x86/include/asm/static_call.h | 3 +-
arch/x86/kernel/alternative.c | 51 +-
arch/x86/kernel/asm-offsets.c | 3 +
arch/x86/kernel/kprobes/opt.c | 4 -
arch/x86/kernel/module.c | 15 +-
arch/x86/um/shared/sysdep/kernel-offsets.h | 2 +
include/asm-generic/vmlinux.lds.h | 40 +-
include/linux/compiler.h | 8 +-
include/linux/elfnote.h | 13 +-
include/linux/init.h | 3 +-
include/linux/livepatch.h | 25 +-
include/linux/livepatch_external.h | 76 +
include/linux/livepatch_helpers.h | 79 +
include/linux/objtool.h | 13 +-
include/linux/static_call.h | 6 -
include/linux/static_call_types.h | 6 +
kernel/bounds.c | 13 +
kernel/livepatch/Kconfig | 12 +
kernel/livepatch/core.c | 8 +-
scripts/Makefile.lib | 6 +-
scripts/Makefile.modfinal | 19 +-
scripts/Makefile.vmlinux_o | 2 +-
scripts/link-vmlinux.sh | 3 +-
scripts/livepatch/fix-patch-lines | 79 +
scripts/livepatch/init.c | 108 ++
scripts/livepatch/klp-build | 831 ++++++++
scripts/mod/devicetable-offsets.c | 1 +
scripts/mod/modpost.c | 5 +
scripts/module.lds.S | 26 +-
tools/include/linux/interval_tree_generic.h | 2 +-
tools/include/linux/livepatch_external.h | 76 +
tools/include/linux/static_call_types.h | 6 +
tools/include/linux/string.h | 14 +
tools/objtool/Build | 4 +-
tools/objtool/Makefile | 48 +-
tools/objtool/arch/loongarch/decode.c | 6 +-
tools/objtool/arch/powerpc/decode.c | 6 +-
tools/objtool/arch/x86/decode.c | 62 +-
tools/objtool/arch/x86/special.c | 2 +-
tools/objtool/builtin-check.c | 95 +-
tools/objtool/builtin-klp.c | 53 +
tools/objtool/check.c | 826 ++++----
tools/objtool/elf.c | 765 ++++++--
tools/objtool/include/objtool/arch.h | 5 +-
tools/objtool/include/objtool/builtin.h | 9 +-
tools/objtool/include/objtool/check.h | 6 +-
tools/objtool/include/objtool/checksum.h | 43 +
.../objtool/include/objtool/checksum_types.h | 25 +
tools/objtool/include/objtool/elf.h | 185 +-
tools/objtool/include/objtool/klp.h | 35 +
tools/objtool/include/objtool/objtool.h | 6 +-
tools/objtool/include/objtool/util.h | 19 +
tools/objtool/include/objtool/warn.h | 40 +
tools/objtool/klp-diff.c | 1677 +++++++++++++++++
tools/objtool/klp-post-link.c | 168 ++
tools/objtool/objtool.c | 42 +-
tools/objtool/orc_gen.c | 8 +-
tools/objtool/special.c | 13 +-
tools/objtool/sync-check.sh | 1 +
tools/objtool/weak.c | 7 +
71 files changed, 5007 insertions(+), 812 deletions(-)
create mode 100644 include/linux/livepatch_external.h
create mode 100644 include/linux/livepatch_helpers.h
create mode 100755 scripts/livepatch/fix-patch-lines
create mode 100644 scripts/livepatch/init.c
create mode 100755 scripts/livepatch/klp-build
create mode 100644 tools/include/linux/livepatch_external.h
create mode 100644 tools/objtool/builtin-klp.c
create mode 100644 tools/objtool/include/objtool/checksum.h
create mode 100644 tools/objtool/include/objtool/checksum_types.h
create mode 100644 tools/objtool/include/objtool/klp.h
create mode 100644 tools/objtool/include/objtool/util.h
create mode 100644 tools/objtool/klp-diff.c
create mode 100644 tools/objtool/klp-post-link.c
Diff between v2 and v3:
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index 04ab3b653a48..1934fa0df888 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -5,7 +5,6 @@ generic-y += device.h
generic-y += dma-mapping.h
generic-y += emergency-restart.h
generic-y += exec.h
-generic-y += extable.h
generic-y += ftrace.h
generic-y += hw_irq.h
generic-y += irq_regs.h
diff --git a/arch/um/include/shared/common-offsets.h b/arch/um/include/shared/common-offsets.h
index 8ca66a1918c3..a6f77cb6aa7e 100644
--- a/arch/um/include/shared/common-offsets.h
+++ b/arch/um/include/shared/common-offsets.h
@@ -18,3 +18,6 @@ DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES);
DEFINE(UM_SECCOMP_ARCH_NATIVE, SECCOMP_ARCH_NATIVE);
+
+DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
+DEFINE(EXTABLE_SIZE, sizeof(struct exception_table_entry));
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 62faa62b5959..448c6bfb71d6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -266,6 +266,7 @@ config X86
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_KRETPROBES
select HAVE_RETHOOK
+ select HAVE_KLP_BUILD if X86_64
select HAVE_LIVEPATCH if X86_64
select HAVE_MIXED_BREAKPOINTS_REGS
select HAVE_MOD_ARCH_SPECIFIC
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index e206e0f96568..eb24d9ba30d7 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -16,8 +16,6 @@
#define ALT_DIRECT_CALL(feature) ((ALT_FLAG_DIRECT_CALL << ALT_FLAGS_SHIFT) | (feature))
#define ALT_CALL_ALWAYS ALT_DIRECT_CALL(X86_FEATURE_ALWAYS)
-#define ALTINSTR_SIZE 14
-
#ifndef __ASSEMBLER__
#include <linux/stddef.h>
@@ -200,7 +198,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
#define ALTINSTR_ENTRY(ft_flags) \
".pushsection .altinstructions, \"aM\", @progbits, " \
- __stringify(ALTINSTR_SIZE) "\n" \
+ __stringify(ALT_INSTR_SIZE) "\n" \
" .long 771b - .\n" /* label */ \
" .long 774f - .\n" /* new instruction */ \
" .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \
@@ -363,7 +361,7 @@ void nop_func(void);
741: \
.skip -(((744f-743f)-(741b-740b)) > 0) * ((744f-743f)-(741b-740b)),0x90 ;\
742: \
- .pushsection .altinstructions, "aM", @progbits, ALTINSTR_SIZE ; \
+ .pushsection .altinstructions, "aM", @progbits, ALT_INSTR_SIZE ;\
altinstr_entry 740b,743f,flag,742b-740b,744f-743f ; \
.popsection ; \
.pushsection .altinstr_replacement,"ax" ; \
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 62dff336f206..e9b6d2d006c6 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -136,9 +136,11 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
#ifdef __KERNEL__
-# include <asm/extable_fixup_types.h>
+#ifndef COMPILE_OFFSETS
+#include <asm/asm-offsets.h>
+#endif
-#define EXTABLE_SIZE 12
+# include <asm/extable_fixup_types.h>
/* Exception table entry */
#ifdef __ASSEMBLER__
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 6081c33e1566..7a6b0e5d85c1 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -12,31 +12,34 @@
#include <linux/stringify.h>
#include <linux/types.h>
-#define JUMP_TABLE_ENTRY(key, label, size) \
- ".pushsection __jump_table, \"aM\", @progbits, " size "\n\t" \
- _ASM_ALIGN "\n\t" \
- ".long 1b - . \n\t" \
- ".long " label " - . \n\t" \
- _ASM_PTR " " key " - . \n\t" \
+#ifndef COMPILE_OFFSETS
+#include <generated/bounds.h>
+#endif
+
+#define JUMP_TABLE_ENTRY(key, label) \
+ ".pushsection __jump_table, \"aM\", @progbits, " \
+ __stringify(JUMP_ENTRY_SIZE) "\n\t" \
+ _ASM_ALIGN "\n\t" \
+ ".long 1b - . \n\t" \
+ ".long " label " - . \n\t" \
+ _ASM_PTR " " key " - . \n\t" \
".popsection \n\t"
/* This macro is also expanded on the Rust side. */
#ifdef CONFIG_HAVE_JUMP_LABEL_HACK
-#define ARCH_STATIC_BRANCH_ASM(key, label, size) \
+#define ARCH_STATIC_BRANCH_ASM(key, label) \
"1: jmp " label " # objtool NOPs this \n\t" \
- JUMP_TABLE_ENTRY(key " + 2", label, size)
+ JUMP_TABLE_ENTRY(key " + 2", label)
#else /* !CONFIG_HAVE_JUMP_LABEL_HACK */
-#define ARCH_STATIC_BRANCH_ASM(key, label, size) \
+#define ARCH_STATIC_BRANCH_ASM(key, label) \
"1: .byte " __stringify(BYTES_NOP5) "\n\t" \
- JUMP_TABLE_ENTRY(key, label, size)
+ JUMP_TABLE_ENTRY(key, label)
#endif /* CONFIG_HAVE_JUMP_LABEL_HACK */
static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
{
- asm goto(ARCH_STATIC_BRANCH_ASM("%c[key] + %c[branch]", "%l[l_yes]", "%c[size]")
- : : [key] "i" (key), [branch] "i" (branch),
- [size] "i" (sizeof(struct jump_entry))
- : : l_yes);
+ asm goto(ARCH_STATIC_BRANCH_ASM("%c0 + %c1", "%l[l_yes]")
+ : : "i" (key), "i" (branch) : : l_yes);
return false;
l_yes:
@@ -47,10 +50,8 @@ static __always_inline bool arch_static_branch_jump(struct static_key * const ke
{
asm goto("1:"
"jmp %l[l_yes]\n\t"
- JUMP_TABLE_ENTRY("%c[key] + %c[branch]", "%l[l_yes]", "%c[size]")
- : : [key] "i" (key), [branch] "i" (branch),
- [size] "i" (sizeof(struct jump_entry))
- : : l_yes);
+ JUMP_TABLE_ENTRY("%c0 + %c1", "%l[l_yes]")
+ : : "i" (key), "i" (branch) : : l_yes);
return false;
l_yes:
diff --git a/arch/x86/include/asm/static_call.h b/arch/x86/include/asm/static_call.h
index 41502bd2afd6..e03ad9bbbf59 100644
--- a/arch/x86/include/asm/static_call.h
+++ b/arch/x86/include/asm/static_call.h
@@ -58,7 +58,8 @@
ARCH_DEFINE_STATIC_CALL_TRAMP(name, __static_call_return0)
#define ARCH_ADD_TRAMP_KEY(name) \
- asm(".pushsection .static_call_tramp_key, \"a\" \n" \
+ asm(".pushsection .static_call_tramp_key, \"aM\", @progbits, " \
+ __stringify(STATIC_CALL_TRAMP_KEY_SIZE) "\n" \
".long " STATIC_CALL_TRAMP_STR(name) " - . \n" \
".long " STATIC_CALL_KEY_STR(name) " - . \n" \
".popsection \n")
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 499dc1ca2050..bacd6c157626 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -622,8 +622,6 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
u8 *instr, *replacement;
struct alt_instr *a, *b;
- BUILD_BUG_ON(ALTINSTR_SIZE != sizeof(struct alt_instr));
-
DPRINTK(ALT, "alt table %px, -> %px", start, end);
/*
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 6259b474073b..3d3eef7fae32 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -123,4 +123,7 @@ static void __used common(void)
OFFSET(ARIA_CTX_rounds, aria_ctx, rounds);
#endif
+ BLANK();
+ DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
+ DEFINE(EXTABLE_SIZE, sizeof(struct exception_table_entry));
}
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 4624d6d916a2..977ee75e047c 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -199,8 +199,6 @@ static struct orc_entry *orc_find(unsigned long ip)
{
static struct orc_entry *orc;
- BUILD_BUG_ON(UNWIND_HINT_SIZE != sizeof(struct unwind_hint));
-
if (ip == 0)
return &null_orc_entry;
diff --git a/arch/x86/um/shared/sysdep/kernel-offsets.h b/arch/x86/um/shared/sysdep/kernel-offsets.h
index 6fd1ed400399..8215a0200ddd 100644
--- a/arch/x86/um/shared/sysdep/kernel-offsets.h
+++ b/arch/x86/um/shared/sysdep/kernel-offsets.h
@@ -1,4 +1,5 @@
/* SPDX-License-Identifier: GPL-2.0 */
+#define COMPILE_OFFSETS
#include <linux/stddef.h>
#include <linux/sched.h>
#include <linux/elf.h>
@@ -7,6 +8,7 @@
#include <linux/audit.h>
#include <asm/mman.h>
#include <asm/seccomp.h>
+#include <asm/extable.h>
/* workaround for a warning with -Wmissing-prototypes */
void foo(void);
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 3a0865e0a1a7..928e175254f6 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -91,7 +91,7 @@
* but exclude '.text..*'.
*
* Special .text.* sections that are typically grouped separately, such as
- * .text.unlikely or .text.hot, must be matched explicitly before invoking
+ * .text.unlikely or .text.hot, must be matched explicitly before using
* TEXT_MAIN.
*/
#define TEXT_MAIN .text .text.[0-9a-zA-Z_]*
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index b90422671874..2039da81cf16 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -287,7 +287,7 @@ static inline void *offset_to_ptr(const int *off)
*/
#define ___ADDRESSABLE(sym, __attrs) \
static void * __used __attrs \
- __UNIQUE_ID(__PASTE(addressable_,sym)) = (void *)(uintptr_t)&sym;
+ __UNIQUE_ID(__PASTE(addressable_, sym)) = (void *)(uintptr_t)&sym;
#define __ADDRESSABLE(sym) \
___ADDRESSABLE(sym, __section(".discard.addressable"))
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 9ff1ecc8e7a8..fdb79dd1ebd8 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -110,20 +110,16 @@ struct static_key {
#endif /* __ASSEMBLY__ */
#ifdef CONFIG_JUMP_LABEL
+#include <asm/jump_label.h>
+
+#ifndef __ASSEMBLY__
+#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
-#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && !defined(__ASSEMBLY__)
-/* Must be defined before including <asm/jump_label.h> */
struct jump_entry {
s32 code;
s32 target;
long key; // key may be far away from the core kernel under KASLR
};
-#endif
-
-#include <asm/jump_label.h>
-
-#ifndef __ASSEMBLY__
-#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
static inline unsigned long jump_entry_code(const struct jump_entry *entry)
{
@@ -142,7 +138,7 @@ static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
return (struct static_key *)((unsigned long)&entry->key + offset);
}
-#else /* !CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE */
+#else
static inline unsigned long jump_entry_code(const struct jump_entry *entry)
{
@@ -159,7 +155,7 @@ static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
return (struct static_key *)((unsigned long)entry->key & ~3UL);
}
-#endif /* !CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE */
+#endif
static inline bool jump_entry_is_branch(const struct jump_entry *entry)
{
@@ -188,8 +184,8 @@ static inline int jump_entry_size(struct jump_entry *entry)
#endif
}
-#endif /* !__ASSEMBLY__ */
-#endif /* CONFIG_JUMP_LABEL */
+#endif
+#endif
#ifndef __ASSEMBLY__
diff --git a/include/linux/livepatch_helpers.h b/include/linux/livepatch_helpers.h
index 09f4a2d53fd7..337bee91d7da 100644
--- a/include/linux/livepatch_helpers.h
+++ b/include/linux/livepatch_helpers.h
@@ -35,6 +35,17 @@
klp_post_unpatch_t __used __section(KLP_CALLBACK_PTRS) \
__PASTE(__KLP_POST_UNPATCH_PREFIX, KLP_OBJNAME) = func
+/*
+ * KLP_STATIC_CALL
+ *
+ * Replace static_call() usage with this macro when create-diff-object
+ * recommends it due to the original static call key living in a module.
+ *
+ * This converts the static call to a regular indirect call.
+ */
+#define KLP_STATIC_CALL(name) \
+ ((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func))
+
/* Syscall patching */
#define KLP_SYSCALL_DEFINE1(name, ...) KLP_SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index d4137a46ee70..7d7bb7f1af69 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -2,14 +2,16 @@
#ifndef _LINUX_OBJTOOL_H
#define _LINUX_OBJTOOL_H
+#ifndef COMPILE_OFFSETS
+#include <generated/bounds.h>
+#endif
+
#include <linux/objtool_types.h>
#ifdef CONFIG_OBJTOOL
#include <asm/asm.h>
-#define UNWIND_HINT_SIZE 12
-
#ifndef __ASSEMBLY__
#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
@@ -33,10 +35,9 @@
*
* For more information, see tools/objtool/Documentation/objtool.txt.
*/
-#define STACK_FRAME_NON_STANDARD(func) \
- asm(".pushsection .discard.func_stack_frame_non_standard, \"aw\"\n\t" \
- ".long " __stringify(func) " - .\n\t" \
- ".popsection")
+#define STACK_FRAME_NON_STANDARD(func) \
+ static void __used __section(".discard.func_stack_frame_non_standard") \
+ *__func_stack_frame_non_standard_##func = func
/*
* STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
@@ -105,7 +106,7 @@
.macro STACK_FRAME_NON_STANDARD func:req
.pushsection .discard.func_stack_frame_non_standard, "aw"
- .long \func - .
+ .quad \func
.popsection
.endm
diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index 78a77a4ae0ea..5210612817f2 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -172,12 +172,6 @@ struct static_call_mod {
struct static_call_site *sites;
};
-/* For finding the key associated with a trampoline */
-struct static_call_tramp_key {
- s32 tramp;
- s32 key;
-};
-
extern void __static_call_update(struct static_call_key *key, void *tramp, void *func);
extern int static_call_mod_init(struct module *mod);
extern int static_call_text_reserved(void *start, void *end);
diff --git a/include/linux/static_call_types.h b/include/linux/static_call_types.h
index 5a00b8b2cf9f..eb772df625d4 100644
--- a/include/linux/static_call_types.h
+++ b/include/linux/static_call_types.h
@@ -34,6 +34,12 @@ struct static_call_site {
s32 key;
};
+/* For finding the key associated with a trampoline */
+struct static_call_tramp_key {
+ s32 tramp;
+ s32 key;
+};
+
#define DECLARE_STATIC_CALL(name, func) \
extern struct static_call_key STATIC_CALL_KEY(name); \
extern typeof(func) STATIC_CALL_TRAMP(name);
diff --git a/kernel/bounds.c b/kernel/bounds.c
index 29b2cd00df2c..f9bc13727721 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -6,12 +6,16 @@
*/
#define __GENERATING_BOUNDS_H
+#define COMPILE_OFFSETS
/* Include headers that define the enum constants of interest */
#include <linux/page-flags.h>
#include <linux/mmzone.h>
#include <linux/kbuild.h>
#include <linux/log2.h>
#include <linux/spinlock_types.h>
+#include <linux/jump_label.h>
+#include <linux/static_call_types.h>
+#include <linux/objtool_types.h>
int main(void)
{
@@ -28,6 +32,15 @@ int main(void)
#else
DEFINE(LRU_GEN_WIDTH, 0);
DEFINE(__LRU_REFS_WIDTH, 0);
+#endif
+#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && defined(CONFIG_JUMP_LABEL)
+ DEFINE(JUMP_ENTRY_SIZE, sizeof(struct jump_entry));
+#endif
+#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
+ DEFINE(STATIC_CALL_TRAMP_KEY_SIZE, sizeof(struct static_call_tramp_key));
+#endif
+#ifdef CONFIG_OBJTOOL
+ DEFINE(UNWIND_HINT_SIZE, sizeof(struct unwind_hint));
#endif
/* End of constants */
diff --git a/kernel/extable.c b/kernel/extable.c
index 0ae3ee2ef266..71f482581cab 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -55,8 +55,6 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
{
const struct exception_table_entry *e;
- BUILD_BUG_ON(EXTABLE_SIZE != sizeof(struct exception_table_entry));
-
e = search_kernel_exception_table(addr);
if (!e)
e = search_module_extables(addr);
diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig
index 53d51ed619a3..4c0a9c18d0b2 100644
--- a/kernel/livepatch/Kconfig
+++ b/kernel/livepatch/Kconfig
@@ -18,3 +18,15 @@ config LIVEPATCH
module uses the interface provided by this option to register
a patch, causing calls to patched functions to be redirected
to new function code contained in the patch module.
+
+config HAVE_KLP_BUILD
+ bool
+ help
+ Arch supports klp-build
+
+config KLP_BUILD
+ def_bool y
+ depends on LIVEPATCH && HAVE_KLP_BUILD
+ select OBJTOOL
+ help
+ Enable klp-build support
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 41420d24e62e..28a1c08e3b22 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -197,7 +197,7 @@ objtool-args = $(objtool-args-y) \
$(if $(delay-objtool), --link) \
$(if $(part-of-module), --module)
-delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT),$(CONFIG_LIVEPATCH))
+delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT),$(CONFIG_KLP_BUILD))
cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@)
cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 878d0d25a461..7a888e1ff70f 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -31,7 +31,8 @@ ccflags-remove-y := $(CC_FLAGS_CFI)
ifdef CONFIG_NEED_MODULE_PERMISSIONS_FIX
cmd_fix_mod_permissions = \
$(OBJCOPY) --set-section-flags __jump_table=alloc,data \
- --set-section-flags __bug_table=alloc,data $@
+ --set-section-flags __bug_table=alloc,data $@ \
+ --set-section-flags .static_call_sites=alloc,data $@
endif
quiet_cmd_ld_ko_o = LD [M] $@
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index acffa3c935f2..59f875236292 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -61,7 +61,7 @@ vmlinux_link()
shift
if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ||
- is_enabled CONFIG_LIVEPATCH; then
+ is_enabled CONFIG_KLP_BUILD; then
# Use vmlinux.o instead of performing the slow LTO link again.
objs=vmlinux.o
libs=
diff --git a/scripts/livepatch/fix-patch-lines b/scripts/livepatch/fix-patch-lines
index 73c5e3dea46e..fa7d4f6592e6 100755
--- a/scripts/livepatch/fix-patch-lines
+++ b/scripts/livepatch/fix-patch-lines
@@ -23,7 +23,7 @@ BEGIN {
in_hunk = 1
- # for @@ -1,3 +1,4 @@:
+ # @@ -1,3 +1,4 @@:
# 1: line number in old file
# 3: how many lines the hunk covers in old file
# 1: line number in new file
diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index f7d88726ed4f..e47056f75475 100755
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -2,12 +2,11 @@
# SPDX-License-Identifier: GPL-2.0
#
# Build a livepatch module
-#
-# shellcheck disable=SC1090
+# shellcheck disable=SC1090,SC2155
-if (( BASH_VERSINFO[0] < 4 \
- || (BASH_VERSINFO[0] == 4 && BASH_VERSINFO[1] < 4) )); then
+if (( BASH_VERSINFO[0] < 4 || \
+ (BASH_VERSINFO[0] == 4 && BASH_VERSINFO[1] < 4) )); then
echo "error: this script requires bash 4.4+" >&2
exit 1
fi
@@ -22,16 +21,16 @@ set -o nounset
shopt -s lastpipe
unset DEBUG_CLONE DIFF_CHECKSUM SKIP_CLEANUP XTRACE
+
REPLACE=1
SHORT_CIRCUIT=0
+JOBS="$(getconf _NPROCESSORS_ONLN)"
+VERBOSE="-s"
shopt -o xtrace | grep -q 'on' && XTRACE=1
+
# Avoid removing the previous $TMP_DIR until args have been fully processed.
KEEP_TMP=1
-CPUS="$(getconf _NPROCESSORS_ONLN)"
-VERBOSE="-s"
-
-
SCRIPT="$(basename "$0")"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
FIX_PATCH_LINES="$SCRIPT_DIR/fix-patch-lines"
@@ -62,7 +61,7 @@ status() {
}
warn() {
- echo "error: $(basename "$SCRIPT"): $*" >&2
+ echo "error: $SCRIPT: $*" >&2
}
die() {
@@ -99,7 +98,7 @@ cleanup() {
revert_patches "--recount"
restore_files
[[ "$KEEP_TMP" -eq 0 ]] && rm -rf "$TMP_DIR"
- true
+ return 0
}
trap_err() {
@@ -116,12 +115,13 @@ Generate a livepatch module.
Options:
-f, --show-first-changed Show address of first changed instruction
- -o, --output <file.ko> Output file [default: livepatch-<patch-name>.ko]
+ -j, --jobs=<jobs> Build jobs to run simultaneously [default: $JOBS]
+ -o, --output=<file.ko> Output file [default: livepatch-<patch-name>.ko]
--no-replace Disable livepatch atomic replace
-v, --verbose Pass V=1 to kernel/module builds
Advanced Options:
- -D, --debug Show symbol/reloc cloning decisions
+ -d, --debug Show symbol/reloc cloning decisions
-S, --short-circuit=STEP Start at build step (requires prior --keep-tmp)
1|orig Build original kernel (default)
2|patched Build patched kernel
@@ -142,8 +142,8 @@ process_args() {
local long
local args
- short="hfo:vDS:T"
- long="help,show-first-changed,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"
+ short="hfj:o:vdS:T"
+ long="help,show-first-changed,jobs:,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"
args=$(getopt --options "$short" --longoptions "$long" -- "$@") || {
echo; usage; exit
@@ -160,6 +160,10 @@ process_args() {
DIFF_CHECKSUM=1
shift
;;
+ -j | --jobs)
+ JOBS="$2"
+ shift 2
+ ;;
-o | --output)
[[ "$2" != *.ko ]] && die "output filename should end with .ko"
OUTFILE="$2"
@@ -176,7 +180,7 @@ process_args() {
VERBOSE="V=1"
shift
;;
- -D | --debug)
+ -d | --debug)
DEBUG_CLONE=1
keep_tmp=1
shift
@@ -233,14 +237,17 @@ validate_config() {
source "$CONFIG" || die "no .config file in $(dirname "$CONFIG")"
xtrace_restore
- [[ -v CONFIG_LIVEPATCH ]] \
- || die "CONFIG_LIVEPATCH not enabled"
+ [[ -v CONFIG_LIVEPATCH ]] || \
+ die "CONFIG_LIVEPATCH not enabled"
- [[ -v CONFIG_GCC_PLUGIN_LATENT_ENTROPY ]] \
- && die "kernel option 'CONFIG_GCC_PLUGIN_LATENT_ENTROPY' not supported"
+ [[ -v CONFIG_KLP_BUILD ]] || \
+ die "CONFIG_KLP_BUILD not enabled"
- [[ -v CONFIG_GCC_PLUGIN_RANDSTRUCT ]] \
- && die "kernel option 'CONFIG_GCC_PLUGIN_RANDSTRUCT' not supported"
+ [[ -v CONFIG_GCC_PLUGIN_LATENT_ENTROPY ]] && \
+ die "kernel option 'CONFIG_GCC_PLUGIN_LATENT_ENTROPY' not supported"
+
+ [[ -v CONFIG_GCC_PLUGIN_RANDSTRUCT ]] && \
+ die "kernel option 'CONFIG_GCC_PLUGIN_RANDSTRUCT' not supported"
return 0
}
@@ -282,7 +289,7 @@ set_kernelversion() {
localversion="$(cd "$SRC" && KERNELVERSION="$localversion" ./scripts/setlocalversion)"
[[ -z "$localversion" ]] && die "setlocalversion failed"
- echo "echo $localversion" > "$file"
+ sed -i "2i echo $localversion; exit 0" scripts/setlocalversion
}
get_patch_files() {
@@ -299,7 +306,7 @@ git_refresh() {
local patch="$1"
local files=()
- [[ ! -d "$SRC/.git" ]] && return
+ [[ ! -e "$SRC/.git" ]] && return
get_patch_files "$patch" | mapfile -t files
@@ -334,7 +341,14 @@ apply_patch() {
[[ ! -f "$patch" ]] && die "$patch doesn't exist"
- ( cd "$SRC" && git apply "${extra_args[@]}" "$patch" )
+ (
+ cd "$SRC"
+
+ # The sed strips the version signature from 'git format-patch',
+ # otherwise 'git apply --recount' warns.
+ sed -n '/^-- /q;p' "$patch" |
+ git apply "${extra_args[@]}"
+ )
APPLIED_PATCHES+=("$patch")
}
@@ -345,7 +359,12 @@ revert_patch() {
local extra_args=("$@")
local tmp=()
- ( cd "$SRC" && git apply --reverse "${extra_args[@]}" "$patch" )
+ (
+ cd "$SRC"
+
+ sed -n '/^-- /q;p' "$patch" |
+ git apply --reverse "${extra_args[@]}"
+ )
git_refresh "$patch"
for p in "${APPLIED_PATCHES[@]}"; do
@@ -373,9 +392,6 @@ revert_patches() {
done
APPLIED_PATCHES=()
-
- # Make sure git actually sees the patches have been reverted.
- [[ -d "$SRC/.git" ]] && (cd "$SRC" && git update-index -q --refresh)
}
validate_patches() {
@@ -412,10 +428,8 @@ refresh_patch() {
mkdir -p "$tmpdir/a"
mkdir -p "$tmpdir/b"
- # Find all source files affected by the patch
- grep0 -E '^(--- |\+\+\+ )[^ /]+' "$patch" |
- sed -E 's/(--- |\+\+\+ )[^ /]+\///' |
- sort | uniq | mapfile -t files
+ # Get all source files affected by the patch
+ get_patch_files "$patch" | mapfile -t files
# Copy orig source files to 'a'
( cd "$SRC" && echo "${files[@]}" | xargs cp --parents --target-directory="$tmpdir/a" )
@@ -459,13 +473,26 @@ fix_patches() {
done
}
+clean_kernel() {
+ local cmd=()
+
+ cmd=("make")
+ cmd+=("--silent")
+ cmd+=("-j$JOBS")
+ cmd+=("clean")
+
+ (
+ cd "$SRC"
+ "${cmd[@]}"
+ )
+}
+
build_kernel() {
local log="$TMP_DIR/build.log"
local objtool_args=()
local cmd=()
objtool_args=("--checksum")
- [[ -v OBJTOOL_ARGS ]] && objtool_args+=("${OBJTOOL_ARGS}")
cmd=("make")
@@ -487,7 +514,7 @@ build_kernel() {
cmd+=("KBUILD_MODPOST_WARN=1")
cmd+=("$VERBOSE")
- cmd+=("-j$CPUS")
+ cmd+=("-j$JOBS")
cmd+=("KCFLAGS=-ffunction-sections -fdata-sections")
cmd+=("OBJTOOL_ARGS=${objtool_args[*]}")
cmd+=("vmlinux")
@@ -496,7 +523,7 @@ build_kernel() {
(
cd "$SRC"
"${cmd[@]}" \
- > >(tee -a "$log") \
+ 1> >(tee -a "$log") \
2> >(tee -a "$log" | grep0 -v "modpost.*undefined!" >&2)
)
}
@@ -512,18 +539,31 @@ find_objects() {
-printf '%P\n'
}
-# Copy all objects (.o archives) to $ORIG_DIR
+# Copy all .o archives to $ORIG_DIR
copy_orig_objects() {
+ local files=()
rm -rf "$ORIG_DIR"
mkdir -p "$ORIG_DIR"
- (
- cd "$OBJ"
- find_objects \
- | sed 's/\.ko$/.o/' \
- | xargs cp --parents --target-directory="$ORIG_DIR"
- )
+ find_objects | mapfile -t files
+
+ xtrace_save "copying orig objects"
+ for _file in "${files[@]}"; do
+ local rel_file="${_file/.ko/.o}"
+ local file="$OBJ/$rel_file"
+ local file_dir="$(dirname "$file")"
+ local orig_file="$ORIG_DIR/$rel_file"
+ local orig_dir="$(dirname "$orig_file")"
+ local cmd_file="$file_dir/.$(basename "$file").cmd"
+
+ [[ ! -f "$file" ]] && die "missing $(basename "$file") for $_file"
+
+ mkdir -p "$orig_dir"
+ cp -f "$file" "$orig_dir"
+ [[ -e "$cmd_file" ]] && cp -f "$cmd_file" "$orig_dir"
+ done
+ xtrace_restore
mv -f "$TMP_DIR/build.log" "$ORIG_DIR"
touch "$TIMESTAMP"
@@ -531,9 +571,9 @@ copy_orig_objects() {
# Copy all changed objects to $PATCHED_DIR
copy_patched_objects() {
- local found
local files=()
local opts=()
+ local found=0
rm -rf "$PATCHED_DIR"
mkdir -p "$PATCHED_DIR"
@@ -544,24 +584,25 @@ copy_patched_objects() {
find_objects "${opts[@]}" | mapfile -t files
- xtrace_save "processing all objects"
+ xtrace_save "copying changed objects"
for _file in "${files[@]}"; do
local rel_file="${_file/.ko/.o}"
local file="$OBJ/$rel_file"
local orig_file="$ORIG_DIR/$rel_file"
local patched_file="$PATCHED_DIR/$rel_file"
+ local patched_dir="$(dirname "$patched_file")"
[[ ! -f "$file" ]] && die "missing $(basename "$file") for $_file"
cmp -s "$orig_file" "$file" && continue
- mkdir -p "$(dirname "$patched_file")"
- cp -f "$file" "$patched_file"
+ mkdir -p "$patched_dir"
+ cp -f "$file" "$patched_dir"
found=1
done
xtrace_restore
- [[ -n "$found" ]] || die "no changes detected"
+ (( found == 0 )) && die "no changes detected"
mv -f "$TMP_DIR/build.log" "$PATCHED_DIR"
}
@@ -610,9 +651,9 @@ diff_objects() {
(
cd "$ORIG_DIR"
"${cmd[@]}" \
- > >(tee -a "$log") \
- 2> >(tee -a "$log" | "${filter[@]}" >&2) \
- || die "objtool klp diff failed"
+ 1> >(tee -a "$log") \
+ 2> >(tee -a "$log" | "${filter[@]}" >&2) || \
+ die "objtool klp diff failed"
)
done
}
@@ -653,12 +694,12 @@ diff_checksums() {
(
cd "$ORIG_DIR"
- "${cmd[@]}" "$opt" "$file" &> "$orig_log" \
- || ( cat "$orig_log" >&2; die "objtool --debug-checksum failed" )
+ "${cmd[@]}" "$opt" "$file" &> "$orig_log" || \
+ ( cat "$orig_log" >&2; die "objtool --debug-checksum failed" )
cd "$PATCHED_DIR"
- "${cmd[@]}" "$opt" "$file" &> "$patched_log" \
- || ( cat "$patched_log" >&2; die "objtool --debug-checksum failed" )
+ "${cmd[@]}" "$opt" "$file" &> "$patched_log" || \
+ ( cat "$patched_log" >&2; die "objtool --debug-checksum failed" )
)
for func in ${funcs[$file]}; do
@@ -677,6 +718,7 @@ diff_checksums() {
build_patch_module() {
local makefile="$KMOD_DIR/Kbuild"
local log="$KMOD_DIR/build.log"
+ local kmod_file
local cflags=()
local files=()
local cmd=()
@@ -694,19 +736,20 @@ build_patch_module() {
for file in "${files[@]}"; do
local rel_file="${file#"$DIFF_DIR"/}"
+ local orig_file="$ORIG_DIR/$rel_file"
+ local orig_dir="$(dirname "$orig_file")"
local kmod_file="$KMOD_DIR/$rel_file"
- local cmd_file
+ local kmod_dir="$(dirname "$kmod_file")"
+ local cmd_file="$orig_dir/.$(basename "$file").cmd"
- mkdir -p "$(dirname "$kmod_file")"
- cp -f "$file" "$kmod_file"
+ mkdir -p "$kmod_dir"
+ cp -f "$file" "$kmod_dir"
+ [[ -e "$cmd_file" ]] && cp -f "$cmd_file" "$kmod_dir"
# Tell kbuild this is a prebuilt object
cp -f "$file" "${kmod_file}_shipped"
echo -n " $rel_file" >> "$makefile"
-
- cmd_file="$ORIG_DIR/$(dirname "$rel_file")/.$(basename "$rel_file").cmd"
- [[ -e "$cmd_file" ]] && cp -f "$cmd_file" "$(dirname "$kmod_file")"
done
echo >> "$makefile"
@@ -717,7 +760,7 @@ build_patch_module() {
cmd=("make")
cmd+=("$VERBOSE")
- cmd+=("-j$CPUS")
+ cmd+=("-j$JOBS")
cmd+=("--directory=.")
cmd+=("M=$KMOD_DIR")
cmd+=("KCFLAGS=${cflags[*]}")
@@ -726,17 +769,22 @@ build_patch_module() {
(
cd "$SRC"
"${cmd[@]}" \
- > >(tee -a "$log") \
+ 1> >(tee -a "$log") \
2> >(tee -a "$log" >&2)
)
+ kmod_file="$KMOD_DIR/$NAME.ko"
+
# Save off the intermediate binary for debugging
- cp -f "$KMOD_DIR/$NAME.ko" "$KMOD_DIR/$NAME.ko.orig"
+ cp -f "$kmod_file" "$kmod_file.orig"
+
+ # Work around issue where slight .config change makes corrupt BTF
+ objcopy --remove-section=.BTF "$kmod_file"
# Fix (and work around) linker wreckage for klp syms / relocs
- "$SRC/tools/objtool/objtool" klp post-link "$KMOD_DIR/$NAME.ko" || die "objtool klp post-link failed"
+ "$SRC/tools/objtool/objtool" klp post-link "$kmod_file" || die "objtool klp post-link failed"
- cp -f "$KMOD_DIR/$NAME.ko" "$OUTFILE"
+ cp -f "$kmod_file" "$OUTFILE"
}
@@ -746,8 +794,10 @@ process_args "$@"
do_init
if (( SHORT_CIRCUIT <= 1 )); then
- status "Building original kernel"
+ status "Validating patches"
validate_patches
+ status "Building original kernel"
+ clean_kernel
build_kernel
status "Copying original object files"
copy_orig_objects
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index d3d00e85edf7..ef2ffb68f69d 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
+#define COMPILE_OFFSETS
#include <linux/kbuild.h>
#include <linux/mod_devicetable.h>
diff --git a/tools/include/linux/static_call_types.h b/tools/include/linux/static_call_types.h
index 5a00b8b2cf9f..eb772df625d4 100644
--- a/tools/include/linux/static_call_types.h
+++ b/tools/include/linux/static_call_types.h
@@ -34,6 +34,12 @@ struct static_call_site {
s32 key;
};
+/* For finding the key associated with a trampoline */
+struct static_call_tramp_key {
+ s32 tramp;
+ s32 key;
+};
+
#define DECLARE_STATIC_CALL(name, func) \
extern struct static_call_key STATIC_CALL_KEY(name); \
extern typeof(func) STATIC_CALL_TRAMP(name);
diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index 8499f509f03e..51ad3cf4fa82 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -44,6 +44,20 @@ static inline bool strstarts(const char *str, const char *prefix)
return strncmp(str, prefix, strlen(prefix)) == 0;
}
+/*
+ * Checks if a string ends with another.
+ */
+static inline bool str_ends_with(const char *str, const char *substr)
+{
+ size_t len = strlen(str);
+ size_t sublen = strlen(substr);
+
+ if (sublen > len)
+ return false;
+
+ return !strcmp(str + len - sublen, substr);
+}
+
extern char * __must_check skip_spaces(const char *);
extern char *strim(char *);
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 3b40afe144fe..c4d6b90b1134 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -83,14 +83,8 @@ s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
{
s64 addend = reloc_addend(reloc);
- switch (reloc_type(reloc)) {
- case R_X86_64_PC32:
- case R_X86_64_PLT32:
+ if (arch_pc_relative_reloc(reloc))
addend += insn->offset + insn->len - reloc_offset(reloc);
- break;
- default:
- break;
- }
return phys_to_virt(addend);
}
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 84918593d935..cd2c4a387100 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -92,6 +92,7 @@ static const struct option check_options[] = {
OPT_GROUP("Options:"),
OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),
+ OPT_BOOLEAN(0, "backup", &opts.backup, "create backup (.orig) file on warning/error"),
OPT_STRING(0, "debug-checksum", &opts.debug_checksum, "funcs", "enable checksum debug output"),
OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"),
@@ -260,12 +261,9 @@ static void save_argv(int argc, const char **argv)
};
}
-void print_args(void)
+int make_backup(void)
{
- char *backup = NULL;
-
- if (opts.output || opts.dryrun)
- goto print;
+ char *backup;
/*
* Make a backup before kbuild deletes the file so the error
@@ -274,33 +272,32 @@ void print_args(void)
backup = malloc(strlen(objname) + strlen(ORIG_SUFFIX) + 1);
if (!backup) {
ERROR_GLIBC("malloc");
- goto print;
+ return 1;
}
strcpy(backup, objname);
strcat(backup, ORIG_SUFFIX);
- if (copy_file(objname, backup)) {
- backup = NULL;
- goto print;
- }
+ if (copy_file(objname, backup))
+ return 1;
-print:
/*
- * Print the cmdline args to make it easier to recreate. If '--output'
- * wasn't used, add it to the printed args with the backup as input.
+ * Print the cmdline args to make it easier to recreate.
*/
+
fprintf(stderr, "%s", orig_argv[0]);
for (int i = 1; i < orig_argc; i++) {
char *arg = orig_argv[i];
- if (backup && !strcmp(arg, objname))
+ /* Modify the printed args to use the backup */
+ if (!opts.output && !strcmp(arg, objname))
fprintf(stderr, " %s -o %s", backup, objname);
else
fprintf(stderr, " %s", arg);
}
fprintf(stderr, "\n");
+ return 0;
}
int objtool_run(int argc, const char **argv)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 9848ca612683..1eb6489ae459 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -187,20 +187,6 @@ static bool is_sibling_call(struct instruction *insn)
return (is_static_jump(insn) && insn_call_dest(insn));
}
-/*
- * Checks if a string ends with another.
- */
-static bool str_ends_with(const char *s, const char *sub)
-{
- const int slen = strlen(s);
- const int sublen = strlen(sub);
-
- if (sublen > slen)
- return 0;
-
- return !memcmp(s + slen - sublen, sub, sublen);
-}
-
/*
* Checks if a function is a Rust "noreturn" one.
*/
@@ -431,7 +417,6 @@ static int decode_instructions(struct objtool_file *file)
struct symbol *func;
unsigned long offset;
struct instruction *insn;
- int ret;
for_each_sec(file->elf, sec) {
struct instruction *insns = NULL;
@@ -480,11 +465,8 @@ static int decode_instructions(struct objtool_file *file)
insn->offset = offset;
insn->prev_len = prev_len;
- ret = arch_decode_instruction(file, sec, offset,
- sec_size(sec) - offset,
- insn);
- if (ret)
- return ret;
+ if (arch_decode_instruction(file, sec, offset, sec_size(sec) - offset, insn))
+ return -1;
prev_len = insn->len;
@@ -600,7 +582,7 @@ static int init_pv_ops(struct objtool_file *file)
};
const char *pv_ops;
struct symbol *sym;
- int idx, nr, ret;
+ int idx, nr;
if (!opts.noinstr)
return 0;
@@ -622,9 +604,8 @@ static int init_pv_ops(struct objtool_file *file)
INIT_LIST_HEAD(&file->pv_ops[idx].targets);
for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++) {
- ret = add_pv_ops(file, pv_ops);
- if (ret)
- return ret;
+ if (add_pv_ops(file, pv_ops))
+ return -1;
}
return 0;
@@ -660,7 +641,7 @@ static int create_static_call_sections(struct objtool_file *file)
* site entries to take advantage of vmlinux static call
* privileges.
*/
- if (!!opts.dryrun || !file->klp)
+ if (!file->klp)
WARN("file already has .static_call_sites section, skipping");
return 0;
@@ -678,8 +659,15 @@ static int create_static_call_sections(struct objtool_file *file)
if (!sec)
return -1;
- /* Allow modules to modify the low bits of static_call_site::key */
- sec->sh.sh_flags |= SHF_WRITE;
+ /*
+ * Set SHF_MERGE to prevent tooling from stripping entsize.
+ *
+ * SHF_WRITE would also get set here to allow modules to modify the low
+ * bits of static_call_site::key, but the LLVM linker doesn't allow
+ * SHF_MERGE+SHF_WRITE for whatever reason. That gets fixed up by the
+ * makefiles with CONFIG_NEED_MODULE_PERMISSIONS_FIX.
+ */
+ sec->sh.sh_flags |= SHF_MERGE;
idx = 0;
list_for_each_entry(insn, &file->static_call_list, call_node) {
@@ -744,9 +732,7 @@ static int create_retpoline_sites_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".retpoline_sites");
if (sec) {
- if (!opts.dryrun)
- WARN("file already has .retpoline_sites, skipping");
-
+ WARN("file already has .retpoline_sites, skipping");
return 0;
}
@@ -784,9 +770,7 @@ static int create_return_sites_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".return_sites");
if (sec) {
- if (!opts.dryrun)
- WARN("file already has .return_sites, skipping");
-
+ WARN("file already has .return_sites, skipping");
return 0;
}
@@ -824,9 +808,7 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
if (sec) {
- if (!opts.dryrun)
- WARN("file already has .ibt_endbr_seal, skipping");
-
+ WARN("file already has .ibt_endbr_seal, skipping");
return 0;
}
@@ -883,9 +865,7 @@ static int create_cfi_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".cfi_sites");
if (sec) {
- if (!opts.dryrun)
- WARN("file already has .cfi_sites section, skipping");
-
+ WARN("file already has .cfi_sites section, skipping");
return 0;
}
@@ -937,7 +917,7 @@ static int create_mcount_loc_sections(struct objtool_file *file)
* Livepatch modules have already extracted their __mcount_loc
* entries to cover the !CONFIG_FTRACE_MCOUNT_USE_OBJTOOL case.
*/
- if (!opts.dryrun && !file->klp)
+ if (!file->klp)
WARN("file already has __mcount_loc section, skipping");
return 0;
@@ -983,9 +963,7 @@ static int create_direct_call_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".call_sites");
if (sec) {
- if (!opts.dryrun)
- WARN("file already has .call_sites section, skipping");
-
+ WARN("file already has .call_sites section, skipping");
return 0;
}
@@ -1548,7 +1526,6 @@ static int add_jump_destinations(struct objtool_file *file)
{
struct instruction *insn;
struct reloc *reloc;
- int ret;
for_each_insn(file, insn) {
struct symbol *func = insn_func(insn);
@@ -1556,7 +1533,6 @@ static int add_jump_destinations(struct objtool_file *file)
struct section *dest_sec;
struct symbol *dest_sym;
unsigned long dest_off;
- bool dest_undef = false;
if (!is_static_jump(insn))
continue;
@@ -1573,78 +1549,85 @@ static int add_jump_destinations(struct objtool_file *file)
if (!reloc) {
dest_sec = insn->sec;
dest_off = arch_jump_destination(insn);
- } else if (is_undef_sym(reloc->sym)) {
- dest_sym = reloc->sym;
- dest_undef = true;
+ dest_sym = dest_sec->sym;
} else {
- dest_sec = reloc->sym->sec;
- dest_off = reloc->sym->sym.st_value +
- arch_insn_adjusted_addend(insn, reloc);
- }
-
- if (!dest_undef) {
- dest_insn = find_insn(file, dest_sec, dest_off);
- if (!dest_insn) {
- struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
-
- /*
- * retbleed_untrain_ret() jumps to
- * __x86_return_thunk(), but objtool can't find
- * the thunk's starting RET instruction,
- * because the RET is also in the middle of
- * another instruction. Objtool only knows
- * about the outer instruction.
- */
- if (sym && sym->embedded_insn) {
- add_return_call(file, insn, false);
+ dest_sym = reloc->sym;
+ if (is_undef_sym(dest_sym)) {
+ if (dest_sym->retpoline_thunk) {
+ if (add_retpoline_call(file, insn))
+ return -1;
continue;
}
- /*
- * GCOV/KCOV dead code can jump to the end of
- * the function/section.
- */
- if (file->ignore_unreachables && func &&
- dest_sec == insn->sec &&
- dest_off == func->offset + func->len)
+ if (dest_sym->return_thunk) {
+ add_return_call(file, insn, true);
continue;
+ }
- ERROR_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
- dest_sec->name, dest_off);
- return -1;
+ /* External symbol */
+ if (func) {
+ /* External sibling call */
+ if (add_call_dest(file, insn, dest_sym, true))
+ return -1;
+ continue;
+ }
+
+ /* Non-func asm code jumping to external symbol */
+ continue;
}
+ dest_sec = dest_sym->sec;
+ dest_off = dest_sym->offset + arch_insn_adjusted_addend(insn, reloc);
+ }
+
+ dest_insn = find_insn(file, dest_sec, dest_off);
+ if (!dest_insn) {
+ struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
+
+ /*
+ * retbleed_untrain_ret() jumps to
+ * __x86_return_thunk(), but objtool can't find
+ * the thunk's starting RET instruction,
+ * because the RET is also in the middle of
+ * another instruction. Objtool only knows
+ * about the outer instruction.
+ */
+ if (sym && sym->embedded_insn) {
+ add_return_call(file, insn, false);
+ continue;
+ }
+
+ /*
+ * GCOV/KCOV dead code can jump to the end of
+ * the function/section.
+ */
+ if (file->ignore_unreachables && func &&
+ dest_sec == insn->sec &&
+ dest_off == func->offset + func->len)
+ continue;
+
+ ERROR_INSN(insn, "can't find jump dest instruction at %s",
+ offstr(dest_sec, dest_off));
+ return -1;
+ }
+
+ if (!dest_sym || is_sec_sym(dest_sym)) {
dest_sym = dest_insn->sym;
if (!dest_sym)
goto set_jump_dest;
}
- if (dest_sym->retpoline_thunk) {
- ret = add_retpoline_call(file, insn);
- if (ret)
- return ret;
+ if (dest_sym->retpoline_thunk && dest_insn->offset == dest_sym->offset) {
+ if (add_retpoline_call(file, insn))
+ return -1;
continue;
}
- if (dest_sym->return_thunk) {
+ if (dest_sym->return_thunk && dest_insn->offset == dest_sym->offset) {
add_return_call(file, insn, true);
continue;
}
- if (dest_undef) {
- /* External symbol */
- if (func) {
- /* External sibling call */
- ret = add_call_dest(file, insn, dest_sym, true);
- if (ret)
- return ret;
- continue;
- }
-
- /* Non-func asm code jumping to external symbol */
- continue;
- }
-
if (!insn->sym || insn->sym == dest_insn->sym)
goto set_jump_dest;
@@ -1675,9 +1658,8 @@ static int add_jump_destinations(struct objtool_file *file)
if (is_first_func_insn(file, dest_insn)) {
/* Internal sibling call */
- ret = add_call_dest(file, insn, dest_sym, true);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, dest_sym, true))
+ return -1;
continue;
}
@@ -1708,7 +1690,6 @@ static int add_call_destinations(struct objtool_file *file)
unsigned long dest_off;
struct symbol *dest;
struct reloc *reloc;
- int ret;
for_each_insn(file, insn) {
struct symbol *func = insn_func(insn);
@@ -1720,9 +1701,8 @@ static int add_call_destinations(struct objtool_file *file)
dest_off = arch_jump_destination(insn);
dest = find_call_destination(insn->sec, dest_off);
- ret = add_call_dest(file, insn, dest, false);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, dest, false))
+ return -1;
if (func && func->ignore)
continue;
@@ -1746,19 +1726,16 @@ static int add_call_destinations(struct objtool_file *file)
return -1;
}
- ret = add_call_dest(file, insn, dest, false);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, dest, false))
+ return -1;
} else if (reloc->sym->retpoline_thunk) {
- ret = add_retpoline_call(file, insn);
- if (ret)
- return ret;
+ if (add_retpoline_call(file, insn))
+ return -1;
} else {
- ret = add_call_dest(file, insn, reloc->sym, false);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, reloc->sym, false))
+ return -1;
}
}
@@ -1976,7 +1953,6 @@ static int add_special_section_alts(struct objtool_file *file)
struct instruction *orig_insn, *new_insn;
struct special_alt *special_alt, *tmp;
struct alternative *alt;
- int ret;
if (special_get_alts(file->elf, &special_alts))
return -1;
@@ -2008,16 +1984,12 @@ static int add_special_section_alts(struct objtool_file *file)
continue;
}
- ret = handle_group_alt(file, special_alt, orig_insn,
- &new_insn);
- if (ret)
- return ret;
+ if (handle_group_alt(file, special_alt, orig_insn, &new_insn))
+ return -1;
} else if (special_alt->jump_or_nop) {
- ret = handle_jump_alt(file, special_alt, orig_insn,
- &new_insn);
- if (ret)
- return ret;
+ if (handle_jump_alt(file, special_alt, orig_insn, &new_insn))
+ return -1;
}
alt = calloc(1, sizeof(*alt));
@@ -2205,15 +2177,13 @@ static int add_func_jump_tables(struct objtool_file *file,
struct symbol *func)
{
struct instruction *insn;
- int ret;
func_for_each_insn(file, func, insn) {
if (!insn_jump_table(insn))
continue;
- ret = add_jump_table(file, insn);
- if (ret)
- return ret;
+ if (add_jump_table(file, insn))
+ return -1;
}
return 0;
@@ -2227,7 +2197,6 @@ static int add_func_jump_tables(struct objtool_file *file,
static int add_jump_table_alts(struct objtool_file *file)
{
struct symbol *func;
- int ret;
if (!file->rodata)
return 0;
@@ -2237,9 +2206,8 @@ static int add_jump_table_alts(struct objtool_file *file)
continue;
mark_func_jump_tables(file, func);
- ret = add_func_jump_tables(file, func);
- if (ret)
- return ret;
+ if (add_func_jump_tables(file, func))
+ return -1;
}
return 0;
@@ -2356,7 +2324,7 @@ static int read_annotate(struct objtool_file *file,
struct instruction *insn;
struct reloc *reloc;
uint64_t offset;
- int type, ret;
+ int type;
sec = find_section_by_name(file->elf, ".discard.annotate_insn");
if (!sec)
@@ -2390,9 +2358,8 @@ static int read_annotate(struct objtool_file *file,
return -1;
}
- ret = func(file, type, insn);
- if (ret < 0)
- return ret;
+ if (func(file, type, insn))
+ return -1;
}
return 0;
@@ -2636,70 +2603,57 @@ static bool validate_branch_enabled(void)
static int decode_sections(struct objtool_file *file)
{
- int ret;
-
file->klp = is_livepatch_module(file);
mark_rodata(file);
- ret = init_pv_ops(file);
- if (ret)
- return ret;
+ if (init_pv_ops(file))
+ return -1;
/*
* Must be before add_{jump_call}_destination.
*/
- ret = classify_symbols(file);
- if (ret)
- return ret;
+ if (classify_symbols(file))
+ return -1;
- ret = decode_instructions(file);
- if (ret)
- return ret;
+ if (decode_instructions(file))
+ return -1;
- ret = add_ignores(file);
- if (ret)
- return ret;
+ if (add_ignores(file))
+ return -1;
add_uaccess_safe(file);
- ret = read_annotate(file, __annotate_early);
- if (ret)
- return ret;
+ if (read_annotate(file, __annotate_early))
+ return -1;
/*
* Must be before add_jump_destinations(), which depends on 'func'
* being set for alternatives, to enable proper sibling call detection.
*/
if (validate_branch_enabled() || opts.noinstr) {
- ret = add_special_section_alts(file);
- if (ret)
- return ret;
+ if (add_special_section_alts(file))
+ return -1;
}
- ret = add_jump_destinations(file);
- if (ret)
- return ret;
+ if (add_jump_destinations(file))
+ return -1;
/*
* Must be before add_call_destination(); it changes INSN_CALL to
* INSN_JUMP.
*/
- ret = read_annotate(file, __annotate_ifc);
- if (ret)
- return ret;
+ if (read_annotate(file, __annotate_ifc))
+ return -1;
- ret = add_call_destinations(file);
- if (ret)
- return ret;
+ if (add_call_destinations(file))
+ return -1;
- ret = add_jump_table_alts(file);
- if (ret)
- return ret;
+ if (add_jump_table_alts(file))
+ return -1;
- ret = read_unwind_hints(file);
- if (ret)
- return ret;
+ if (read_unwind_hints(file))
+ return -1;
/* Must be after add_jump_destinations() */
mark_holes(file);
@@ -2708,9 +2662,8 @@ static int decode_sections(struct objtool_file *file)
* Must be after add_call_destinations() such that it can override
* dead_end_function() marks.
*/
- ret = read_annotate(file, __annotate_late);
- if (ret)
- return ret;
+ if (read_annotate(file, __annotate_late))
+ return -1;
return 0;
}
@@ -3464,7 +3417,7 @@ static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
if (!reloc || strcmp(reloc->sym->name, "pv_ops"))
return false;
- idx = (arch_insn_adjusted_addend(insn, reloc) / sizeof(void *));
+ idx = arch_insn_adjusted_addend(insn, reloc) / sizeof(void *);
if (file->pv_ops[idx].clean)
return true;
@@ -3692,45 +3645,44 @@ static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
struct instruction *insn)
{
struct reloc *reloc = insn_reloc(file, insn);
- struct symbol *dest = insn_call_dest(insn);
+ unsigned long offset;
+ struct symbol *sym;
- if (dest && !reloc) {
- checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, 1);
- checksum_update(func, insn, dest->name, strlen(dest->name));
- } else if (!insn->fake) {
- checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);
+ if (insn->fake)
+ return;
+
+ checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);
+
+ if (!reloc) {
+ struct symbol *call_dest = insn_call_dest(insn);
+
+ if (call_dest)
+ checksum_update(func, insn, call_dest->demangled_name,
+ strlen(call_dest->demangled_name));
+ return;
}
- if (reloc) {
- struct symbol *sym = reloc->sym;
+ sym = reloc->sym;
+ offset = arch_insn_adjusted_addend(insn, reloc);
- if (sym->sec && is_string_sec(sym->sec)) {
- s64 addend;
- char *str;
+ if (is_string_sec(sym->sec)) {
+ char *str;
- addend = arch_insn_adjusted_addend(insn, reloc);
-
- str = sym->sec->data->d_buf + sym->offset + addend;
-
- checksum_update(func, insn, str, strlen(str));
-
- } else {
- u64 offset = arch_insn_adjusted_addend(insn, reloc);
-
- if (is_sec_sym(sym)) {
- sym = find_symbol_containing(reloc->sym->sec, offset);
- if (!sym)
- return;
-
- offset -= sym->offset;
- }
-
- checksum_update(func, insn, sym->demangled_name,
- strlen(sym->demangled_name));
-
- checksum_update(func, insn, &offset, sizeof(offset));
- }
+ str = sym->sec->data->d_buf + sym->offset + offset;
+ checksum_update(func, insn, str, strlen(str));
+ return;
}
+
+ if (is_sec_sym(sym)) {
+ sym = find_symbol_containing(reloc->sym->sec, offset);
+ if (!sym)
+ return;
+
+ offset -= sym->offset;
+ }
+
+ checksum_update(func, insn, sym->demangled_name, strlen(sym->demangled_name));
+ checksum_update(func, insn, &offset, sizeof(offset));
}
/*
@@ -4992,9 +4944,11 @@ int check(struct objtool_file *file)
if (opts.verbose) {
if (opts.werror && warnings)
WARN("%d warning(s) upgraded to errors", warnings);
- print_args();
disas_warned_funcs(file);
}
+ if (opts.backup && make_backup())
+ return 1;
+
return ret;
}
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index ae1c852ff8d8..f9eed5d50de5 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -492,8 +492,8 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
elf_hash_add(symbol, &sym->hash, sym->idx);
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
- if (is_func_sym(sym) && sym->len == 16 &&
- (strstarts(sym->name, "__pfx") || strstarts(sym->name, "__cfi_")))
+ if (is_func_sym(sym) &&
+ (strstarts(sym->name, "__pfx_") || strstarts(sym->name, "__cfi_")))
sym->prefix = 1;
if (strstarts(sym->name, ".klp.sym"))
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index e8eb3c54c373..e60438577000 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -30,6 +30,7 @@ struct opts {
/* options: */
bool backtrace;
+ bool backup;
const char *debug_checksum;
bool dryrun;
bool link;
@@ -49,7 +50,7 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[]);
int objtool_run(int argc, const char **argv);
-void print_args(void);
+int make_backup(void);
int cmd_klp(int argc, const char **argv);
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index adfe508f96f5..1212f81f40e0 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -17,7 +17,7 @@
#include <objtool/checksum_types.h>
#include <arch/elf.h>
-#define SEC_NAME_LEN 512
+#define SEC_NAME_LEN 1024
#define SYM_NAME_LEN 512
#ifdef LIBELF_USE_DEPRECATED
diff --git a/tools/objtool/include/objtool/util.h b/tools/objtool/include/objtool/util.h
new file mode 100644
index 000000000000..a0180b312f73
--- /dev/null
+++ b/tools/objtool/include/objtool/util.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _UTIL_H
+#define _UTIL_H
+
+#include <objtool/warn.h>
+
+#define snprintf_check(str, size, format, args...) \
+({ \
+ int __ret = snprintf(str, size, format, args); \
+ if (__ret < 0) \
+ ERROR_GLIBC("snprintf"); \
+ else if (__ret >= size) \
+ ERROR("snprintf() failed for '" format "'", args); \
+ else \
+ __ret = 0; \
+ __ret; \
+})
+
+#endif /* _UTIL_H */
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index 144525e74da3..15b554b53da6 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -11,6 +11,7 @@
#include <objtool/warn.h>
#include <objtool/arch.h>
#include <objtool/klp.h>
+#include <objtool/util.h>
#include <arch/special.h>
#include <linux/livepatch_external.h>
@@ -80,42 +81,11 @@ static char *escape_str(const char *orig)
return new;
}
-/*
- * Do a sanity check to make sure the changed object was built with
- * -ffunction-sections and -fdata-sections.
- */
-static int validate_ffunction_fdata_sections(struct elf *elf)
-{
- struct symbol *sym;
- bool found_text = false, found_data = false;
-
- for_each_sym(elf, sym) {
- char sec_name[SEC_NAME_LEN];
-
- if (!found_text && is_func_sym(sym)) {
- snprintf(sec_name, SEC_NAME_LEN, ".text.%s", sym->name);
- if (!strcmp(sym->sec->name, sec_name))
- found_text = true;
- }
-
- if (!found_data && is_object_sym(sym)) {
- snprintf(sec_name, SEC_NAME_LEN, ".data.%s", sym->name);
- if (!strcmp(sym->sec->name, sec_name))
- found_data = true;
- }
-
- if (found_text && found_data)
- return 0;
- }
-
- ERROR("changed object '%s' not built with -ffunction-sections and -fdata-sections", elf->name);
- return -1;
-}
-
static int read_exports(void)
{
const char *symvers = "Module.symvers";
char line[1024], *path = NULL;
+ unsigned int line_num = 1;
FILE *file;
file = fopen(symvers, "r");
@@ -134,12 +104,12 @@ static int read_exports(void)
}
while (fgets(line, 1024, file)) {
- char *sym, *mod, *exp;
+ char *sym, *mod, *type;
struct export *export;
sym = strchr(line, '\t');
if (!sym) {
- ERROR("malformed Module.symvers");
+ ERROR("malformed Module.symvers (sym) at line %d", line_num);
return -1;
}
@@ -147,22 +117,22 @@ static int read_exports(void)
mod = strchr(sym, '\t');
if (!mod) {
- ERROR("malformed Module.symvers");
+ ERROR("malformed Module.symvers (mod) at line %d", line_num);
return -1;
}
*mod++ = '\0';
- exp = strchr(mod, '\t');
- if (!exp) {
- ERROR("malformed Module.symvers");
+ type = strchr(mod, '\t');
+ if (!type) {
+ ERROR("malformed Module.symvers (type) at line %d", line_num);
return -1;
}
- *exp++ = '\0';
+ *type++ = '\0';
if (*sym == '\0' || *mod == '\0') {
- ERROR("malformed Module.symvers");
+ ERROR("malformed Module.symvers at line %d", line_num);
return -1;
}
@@ -177,6 +147,7 @@ static int read_exports(void)
ERROR_GLIBC("strdup");
return -1;
}
+
export->sym = strdup(sym);
if (!export->sym) {
ERROR_GLIBC("strdup");
@@ -244,18 +215,20 @@ static struct symbol *first_file_symbol(struct elf *elf)
{
struct symbol *sym;
- for_each_sym(elf, sym)
+ for_each_sym(elf, sym) {
if (is_file_sym(sym))
return sym;
+ }
return NULL;
}
static struct symbol *next_file_symbol(struct elf *elf, struct symbol *sym)
{
- for_each_sym_continue(elf, sym)
+ for_each_sym_continue(elf, sym) {
if (is_file_sym(sym))
return sym;
+ }
return NULL;
}
@@ -267,11 +240,14 @@ static struct symbol *next_file_symbol(struct elf *elf, struct symbol *sym)
static bool is_uncorrelated_static_local(struct symbol *sym)
{
static const char * const vars[] = {
- "__key.",
- "__warned.",
"__already_done.",
"__func__.",
+ "__key.",
+ "__warned.",
+ "_entry.",
+ "_entry_ptr.",
"_rs.",
+ "descriptor.",
"CSWTCH.",
};
@@ -324,14 +300,19 @@ static bool is_special_section(struct section *sec)
SYM_CHECKSUM_SEC,
};
- for (int i = 0; i < ARRAY_SIZE(specials); i++)
+ if (is_text_sec(sec))
+ return false;
+
+ for (int i = 0; i < ARRAY_SIZE(specials); i++) {
if (!strcmp(sec->name, specials[i]))
return true;
+ }
- /* Most .discard sections are special */
- for (int i = 0; i < ARRAY_SIZE(non_special_discards); i++)
+ /* Most .discard data sections are special */
+ for (int i = 0; i < ARRAY_SIZE(non_special_discards); i++) {
if (!strcmp(sec->name, non_special_discards[i]))
return false;
+ }
return strstarts(sec->name, ".discard.");
}
@@ -347,9 +328,10 @@ static bool is_special_section_aux(struct section *sec)
".altinstr_aux",
};
- for (int i = 0; i < ARRAY_SIZE(specials_aux); i++)
+ for (int i = 0; i < ARRAY_SIZE(specials_aux); i++) {
if (!strcmp(sec->name, specials_aux[i]))
return true;
+ }
return false;
}
@@ -460,6 +442,7 @@ static int correlate_symbols(struct elfs *e)
/* "sympos" is used by livepatch to disambiguate duplicate symbol names */
static unsigned long find_sympos(struct elf *elf, struct symbol *sym)
{
+ bool vmlinux = str_ends_with(objname, "vmlinux.o");
unsigned long sympos = 0, nr_matches = 0;
bool has_dup = false;
struct symbol *s;
@@ -467,13 +450,43 @@ static unsigned long find_sympos(struct elf *elf, struct symbol *sym)
if (sym->bind != STB_LOCAL)
return 0;
- for_each_sym(elf, s) {
- if (!strcmp(s->name, sym->name)) {
- nr_matches++;
- if (s == sym)
- sympos = nr_matches;
- else
- has_dup = true;
+ if (vmlinux && sym->type == STT_FUNC) {
+ /*
+ * HACK: Unfortunately, symbol ordering can differ between
+ * vmlinux.o and vmlinux due to the linker script emitting
+ * .text.unlikely* before .text*. Count .text.unlikely* first.
+ *
+ * TODO: Disambiguate symbols more reliably (checksums?)
+ */
+ for_each_sym(elf, s) {
+ if (strstarts(s->sec->name, ".text.unlikely") &&
+ !strcmp(s->name, sym->name)) {
+ nr_matches++;
+ if (s == sym)
+ sympos = nr_matches;
+ else
+ has_dup = true;
+ }
+ }
+ for_each_sym(elf, s) {
+ if (!strstarts(s->sec->name, ".text.unlikely") &&
+ !strcmp(s->name, sym->name)) {
+ nr_matches++;
+ if (s == sym)
+ sympos = nr_matches;
+ else
+ has_dup = true;
+ }
+ }
+ } else {
+ for_each_sym(elf, s) {
+ if (!strcmp(s->name, sym->name)) {
+ nr_matches++;
+ if (s == sym)
+ sympos = nr_matches;
+ else
+ has_dup = true;
+ }
}
}
@@ -565,7 +578,7 @@ static const char *sym_type(struct symbol *sym)
static const char *sym_bind(struct symbol *sym)
{
switch (sym->bind) {
- case STB_LOCAL : return "LOCAL";
+ case STB_LOCAL: return "LOCAL";
case STB_GLOBAL: return "GLOBAL";
case STB_WEAK: return "WEAK";
default: return "UNKNOWN";
@@ -727,7 +740,7 @@ static struct export *find_export(struct symbol *sym)
static const char *__find_modname(struct elfs *e)
{
- struct section *sec;
+ struct section *sec;
char *name;
sec = find_section_by_name(e->orig, ".modinfo");
@@ -795,7 +808,7 @@ static bool klp_reloc_needed(struct reloc *patched_reloc)
/*
* If exported by a module, it has to be a klp reloc. Thanks to the
- * clusterfoot that is late module patching, the patch module is
+ * clusterfunk that is late module patching, the patch module is
* allowed to be loaded before any modules it depends on.
*
* If exported by vmlinux, a normal reloc will do.
@@ -942,8 +955,9 @@ static int clone_reloc_klp(struct elfs *e, struct reloc *patched_reloc,
}
/* symbol format: .klp.sym.modname.sym_name,sympos */
- snprintf(sym_name, SYM_NAME_LEN, KLP_SYM_PREFIX "%s.%s,%ld",
- sym_modname, sym_orig_name, sympos);
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_SYM_PREFIX "%s.%s,%ld",
+ sym_modname, sym_orig_name, sympos))
+ return -1;
klp_sym = find_symbol_by_name(e->out, sym_name);
if (!klp_sym) {
@@ -1155,11 +1169,102 @@ static bool should_keep_special_sym(struct elf *elf, struct symbol *sym)
return false;
}
+/*
+ * Klp relocations aren't allowed for __jump_table and .static_call_sites if
+ * the referenced symbol lives in a kernel module, because such klp relocs may
+ * be applied after static branch/call init, resulting in code corruption.
+ *
+ * Validate a special section entry to avoid that. Note that an inert
+ * tracepoint is harmless enough, in that case just skip the entry and print a
+ * warning. Otherwise, return an error.
+ *
+ * This is only a temporary limitation which will be fixed when livepatch adds
+ * support for submodules: fully self-contained modules which are embedded in
+ * the top-level livepatch module's data and which can be loaded on demand when
+ * their corresponding to-be-patched module gets loaded. Then klp relocs can
+ * be retired.
+ *
+ * Return:
+ * -1: error: validation failed
+ * 1: warning: tracepoint skipped
+ * 0: success
+ */
+static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym)
+{
+ bool static_branch = !strcmp(sym->sec->name, "__jump_table");
+ bool static_call = !strcmp(sym->sec->name, ".static_call_sites");
+ struct symbol *code_sym = NULL;
+ unsigned long code_offset = 0;
+ struct reloc *reloc;
+ int ret = 0;
+
+ if (!static_branch && !static_call)
+ return 0;
+
+ sym_for_each_reloc(e->patched, sym, reloc) {
+ const char *sym_modname;
+ struct export *export;
+
+ /* Static branch/call keys are always STT_OBJECT */
+ if (reloc->sym->type != STT_OBJECT) {
+
+ /* Save code location which can be printed below */
+ if (reloc->sym->type == STT_FUNC && !code_sym) {
+ code_sym = reloc->sym;
+ code_offset = reloc_addend(reloc);
+ }
+
+ continue;
+ }
+
+ if (!klp_reloc_needed(reloc))
+ continue;
+
+ export = find_export(reloc->sym);
+ if (export) {
+ sym_modname = export->mod;
+ } else {
+ sym_modname = find_modname(e);
+ if (!sym_modname)
+ return -1;
+ }
+
+ /* vmlinux keys are ok */
+ if (!strcmp(sym_modname, "vmlinux"))
+ continue;
+
+ if (static_branch) {
+ if (strstarts(reloc->sym->name, "__tracepoint_")) {
+ WARN("%s: disabling unsupported tracepoint %s",
+ code_sym->name, reloc->sym->name + 13);
+ ret = 1;
+ continue;
+ }
+
+ ERROR("%s+0x%lx: unsupported static branch key %s. Use static_key_enabled() instead",
+ code_sym->name, code_offset, reloc->sym->name);
+ return -1;
+ }
+
+ /* static call */
+ if (strstarts(reloc->sym->name, "__SCK__tp_func_")) {
+ ret = 1;
+ continue;
+ }
+
+ ERROR("%s()+0x%lx: unsupported static call key %s. Use KLP_STATIC_CALL() instead",
+ code_sym->name, code_offset, reloc->sym->name);
+ return -1;
+ }
+
+ return ret;
+}
+
static int special_section_entry_size(struct section *sec)
{
unsigned int reloc_size;
- if (sec->sh.sh_entsize)
+ if ((sec->sh.sh_flags & SHF_MERGE) && sec->sh.sh_entsize)
return sec->sh.sh_entsize;
if (!sec->rsec)
@@ -1176,12 +1281,13 @@ static int special_section_entry_size(struct section *sec)
static int create_fake_symbol(struct elf *elf, struct section *sec,
unsigned long offset, size_t size)
{
+ char name[SYM_NAME_LEN];
unsigned int type;
- char name[256];
static int ctr;
char *c;
- snprintf(name, 256, "__DISCARD_%s_%d", sec->name, ctr++);
+ if (snprintf_check(name, SYM_NAME_LEN, "__DISCARD_%s_%d", sec->name, ctr++))
+ return -1;
for (c = name; *c; c++)
if (*c == '.')
@@ -1206,7 +1312,15 @@ static int clone_special_section(struct elfs *e, struct section *patched_sec)
entry_size = special_section_entry_size(patched_sec);
if (!entry_size) {
- ERROR("%s: unknown entry size", patched_sec->name);
+ /*
+ * Any special section more complex than a simple array of
+ * pointers must have its entry size specified in sh_entsize
+ * (and the SHF_MERGE flag set so the linker preserves it).
+ *
+ * Clang older than version 20 doesn't properly preserve
+ * sh_entsize and will error out here.
+ */
+ ERROR("%s: buggy linker and/or missing sh_entsize", patched_sec->name);
return -1;
}
@@ -1242,12 +1356,20 @@ static int clone_special_section(struct elfs *e, struct section *patched_sec)
* reference included functions.
*/
sec_for_each_sym(patched_sec, patched_sym) {
+ int ret;
+
if (!is_object_sym(patched_sym))
continue;
if (!should_keep_special_sym(e->patched, patched_sym))
continue;
+ ret = validate_special_section_klp_reloc(e, patched_sym);
+ if (ret < 0)
+ return -1;
+ if (ret > 0)
+ continue;
+
if (!clone_symbol(e, patched_sym, true))
return -1;
}
@@ -1388,7 +1510,9 @@ static int create_klp_sections(struct elfs *e)
* friends, and add them to the klp object.
*/
- snprintf(sym_name, SYM_NAME_LEN, KLP_PRE_PATCH_PREFIX "%s", modname);
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_PRE_PATCH_PREFIX "%s", modname))
+ return -1;
+
sym = find_symbol_by_name(e->out, sym_name);
if (sym) {
struct reloc *reloc;
@@ -1402,7 +1526,9 @@ static int create_klp_sections(struct elfs *e)
return -1;
}
- snprintf(sym_name, SYM_NAME_LEN, KLP_POST_PATCH_PREFIX "%s", modname);
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_POST_PATCH_PREFIX "%s", modname))
+ return -1;
+
sym = find_symbol_by_name(e->out, sym_name);
if (sym) {
struct reloc *reloc;
@@ -1416,7 +1542,9 @@ static int create_klp_sections(struct elfs *e)
return -1;
}
- snprintf(sym_name, SYM_NAME_LEN, KLP_PRE_UNPATCH_PREFIX "%s", modname);
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_PRE_UNPATCH_PREFIX "%s", modname))
+ return -1;
+
sym = find_symbol_by_name(e->out, sym_name);
if (sym) {
struct reloc *reloc;
@@ -1430,7 +1558,9 @@ static int create_klp_sections(struct elfs *e)
return -1;
}
- snprintf(sym_name, SYM_NAME_LEN, KLP_POST_UNPATCH_PREFIX "%s", modname);
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_POST_UNPATCH_PREFIX "%s", modname))
+ return -1;
+
sym = find_symbol_by_name(e->out, sym_name);
if (sym) {
struct reloc *reloc;
@@ -1447,6 +1577,51 @@ static int create_klp_sections(struct elfs *e)
return 0;
}
+/*
+ * Copy all .modinfo import_ns= tags to ensure all namespaced exported symbols
+ * can be accessed via normal relocs.
+ */
+static int copy_import_ns(struct elfs *e)
+{
+ struct section *patched_sec, *out_sec = NULL;
+ char *import_ns, *data_end;
+
+ patched_sec = find_section_by_name(e->patched, ".modinfo");
+ if (!patched_sec)
+ return 0;
+
+ import_ns = patched_sec->data->d_buf;
+ if (!import_ns)
+ return 0;
+
+ for (data_end = import_ns + sec_size(patched_sec);
+ import_ns < data_end;
+ import_ns += strlen(import_ns) + 1) {
+
+ import_ns = memmem(import_ns, data_end - import_ns, "import_ns=", 10);
+ if (!import_ns)
+ return 0;
+
+ if (!out_sec) {
+ out_sec = find_section_by_name(e->out, ".modinfo");
+ if (!out_sec) {
+ out_sec = elf_create_section(e->out, ".modinfo", 0,
+ patched_sec->sh.sh_entsize,
+ patched_sec->sh.sh_type,
+ patched_sec->sh.sh_addralign,
+ patched_sec->sh.sh_flags);
+ if (!out_sec)
+ return -1;
+ }
+ }
+
+ if (!elf_add_data(e->out, out_sec, import_ns, strlen(import_ns) + 1))
+ return -1;
+ }
+
+ return 0;
+}
+
int cmd_klp_diff(int argc, const char **argv)
{
struct elfs e = {0};
@@ -1479,10 +1654,6 @@ int cmd_klp_diff(int argc, const char **argv)
if (mark_changed_functions(&e))
return 0;
- if (validate_ffunction_fdata_sections(e.orig) ||
- validate_ffunction_fdata_sections(e.patched))
- return -1;
-
e.out = elf_create_file(&e.orig->ehdr, argv[2]);
if (!e.out)
return -1;
@@ -1496,9 +1667,11 @@ int cmd_klp_diff(int argc, const char **argv)
if (create_klp_sections(&e))
return -1;
+ if (copy_import_ns(&e))
+ return -1;
+
if (elf_write(e.out))
return -1;
return elf_close(e.out);
}
-
diff --git a/tools/objtool/klp-post-link.c b/tools/objtool/klp-post-link.c
index 05be6251e35f..c013e39957b1 100644
--- a/tools/objtool/klp-post-link.c
+++ b/tools/objtool/klp-post-link.c
@@ -16,6 +16,7 @@
#include <objtool/objtool.h>
#include <objtool/warn.h>
#include <objtool/klp.h>
+#include <objtool/util.h>
#include <linux/livepatch_external.h>
static int fix_klp_relocs(struct elf *elf)
@@ -81,8 +82,10 @@ static int fix_klp_relocs(struct elf *elf)
*/
/* section format: .klp.rela.sec_objname.section_name */
- snprintf(rsec_name, SEC_NAME_LEN, KLP_RELOC_SEC_PREFIX "%s.%s",
- sym_modname, sec->name);
+ if (snprintf_check(rsec_name, SEC_NAME_LEN,
+ KLP_RELOC_SEC_PREFIX "%s.%s",
+ sym_modname, sec->name))
+ return -1;
klp_rsec = find_section_by_name(elf, rsec_name);
if (!klp_rsec) {
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index 9cfdd424e173..fc2cf8dba1c0 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -133,7 +133,7 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
struct section *sec;
unsigned int nr_entries;
struct special_alt *alt;
- int idx, ret;
+ int idx;
INIT_LIST_HEAD(alts);
@@ -157,11 +157,8 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
}
memset(alt, 0, sizeof(*alt));
- ret = get_alt_entry(elf, entry, sec, idx, alt);
- if (ret > 0)
- continue;
- if (ret < 0)
- return ret;
+ if (get_alt_entry(elf, entry, sec, idx, alt))
+ return -1;
list_add_tail(&alt->list, alts);
}
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 01/64] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-27 9:34 ` Heiko Carstens
2025-06-26 23:54 ` [PATCH v3 02/64] vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros Josh Poimboeuf
` (62 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Heiko Carstens, Vasily Gorbik,
Alexander Gordeev
The s390 indirect thunks are placed in the .text.__s390_indirect_jump_*
sections.
Certain config options which enable -ffunction-sections have a custom
version of the TEXT_TEXT macro:
.text.[0-9a-zA-Z_]*
That unintentionally matches the thunk sections, causing them to get
grouped with normal text rather than being handled by their intended
rule later in the script:
*(.text.*_indirect_*)
Fix that by adding another period to the thunk section names, following
the kernel's general convention for distinguishing code-generated text
sections from compiler-generated ones.
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/s390/include/asm/nospec-insn.h | 2 +-
arch/s390/kernel/vmlinux.lds.S | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/s390/include/asm/nospec-insn.h b/arch/s390/include/asm/nospec-insn.h
index cb15dd25bf21..84372c3f313a 100644
--- a/arch/s390/include/asm/nospec-insn.h
+++ b/arch/s390/include/asm/nospec-insn.h
@@ -18,7 +18,7 @@
#ifdef CONFIG_EXPOLINE_EXTERN
SYM_CODE_START(\name)
#else
- .pushsection .text.\name,"axG",@progbits,\name,comdat
+ .pushsection .text..\name,"axG",@progbits,\name,comdat
.globl \name
.hidden \name
.type \name,@function
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index ff1ddba96352..fbd6d1f83b67 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -51,7 +51,7 @@ SECTIONS
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
FTRACE_HOTPATCH_TRAMPOLINES_TEXT
- *(.text.*_indirect_*)
+ *(.text..*_indirect_*)
*(.gnu.warning)
. = ALIGN(PAGE_SIZE);
_etext = .; /* End of text section */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 02/64] vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 01/64] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 03/64] x86/module: Improve relocation error messages Josh Poimboeuf
` (61 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Heiko Carstens, Vasily Gorbik,
Alexander Gordeev
TEXT_MAIN, DATA_MAIN and friends are defined differently depending on
whether certain config options enable -ffunction-sections and/or
-fdata-sections.
There's no technical reason for that beyond voodoo coding. Keeping the
separate implementations adds unnecessary complexity, fragments the
logic, and increases the risk of subtle bugs.
Unify the macros by using the same input section patterns across all
configs.
This is a prerequisite for the upcoming livepatch klp-build tooling
which will manually enable -ffunction-sections and -fdata-sections via
KCFLAGS.
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/asm-generic/vmlinux.lds.h | 40 ++++++++++---------------------
scripts/module.lds.S | 16 ++++---------
2 files changed, 17 insertions(+), 39 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index fa5f19b8d53a..928e175254f6 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -87,39 +87,24 @@
#define ALIGN_FUNCTION() . = ALIGN(CONFIG_FUNCTION_ALIGNMENT)
/*
- * LD_DEAD_CODE_DATA_ELIMINATION option enables -fdata-sections, which
- * generates .data.identifier sections, which need to be pulled in with
- * .data. We don't want to pull in .data..other sections, which Linux
- * has defined. Same for text and bss.
+ * Support -ffunction-sections by matching .text and .text.*,
+ * but exclude '.text..*'.
*
- * With LTO_CLANG, the linker also splits sections by default, so we need
- * these macros to combine the sections during the final link.
- *
- * With AUTOFDO_CLANG and PROPELLER_CLANG, by default, the linker splits
- * text sections and regroups functions into subsections.
- *
- * RODATA_MAIN is not used because existing code already defines .rodata.x
- * sections to be brought in with rodata.
+ * Special .text.* sections that are typically grouped separately, such as
+ * .text.unlikely or .text.hot, must be matched explicitly before using
+ * TEXT_MAIN.
*/
-#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG) || \
-defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
#define TEXT_MAIN .text .text.[0-9a-zA-Z_]*
-#else
-#define TEXT_MAIN .text
-#endif
-#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG)
+
+/*
+ * Support -fdata-sections by matching .data, .data.*, and others,
+ * but exclude '.data..*'.
+ */
#define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data.rel.* .data..L* .data..compoundliteral* .data.$__unnamed_* .data.$L*
#define SDATA_MAIN .sdata .sdata.[0-9a-zA-Z_]*
#define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]* .rodata..L*
#define BSS_MAIN .bss .bss.[0-9a-zA-Z_]* .bss..L* .bss..compoundliteral*
#define SBSS_MAIN .sbss .sbss.[0-9a-zA-Z_]*
-#else
-#define DATA_MAIN .data .data.rel .data.rel.local
-#define SDATA_MAIN .sdata
-#define RODATA_MAIN .rodata
-#define BSS_MAIN .bss
-#define SBSS_MAIN .sbss
-#endif
/*
* GCC 4.5 and later have a 32 bytes section alignment for structures.
@@ -580,9 +565,8 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
* during second ld run in second ld pass when generating System.map
*
* TEXT_MAIN here will match symbols with a fixed pattern (for example,
- * .text.hot or .text.unlikely) if dead code elimination or
- * function-section is enabled. Match these symbols first before
- * TEXT_MAIN to ensure they are grouped together.
+ * .text.hot or .text.unlikely). Match those before TEXT_MAIN to ensure
+ * they get grouped together.
*
* Also placing .text.hot section at the beginning of a page, this
* would help the TLB performance.
diff --git a/scripts/module.lds.S b/scripts/module.lds.S
index 450f1088d5fd..0b5ea63d1c67 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -38,12 +38,10 @@ SECTIONS {
__kcfi_traps : { KEEP(*(.kcfi_traps)) }
#endif
-#ifdef CONFIG_LTO_CLANG
- /*
- * With CONFIG_LTO_CLANG, LLD always enables -fdata-sections and
- * -ffunction-sections, which increases the size of the final module.
- * Merge the split sections in the final binary.
- */
+ .text : {
+ *(.text .text.[0-9a-zA-Z_]*)
+ }
+
.bss : {
*(.bss .bss.[0-9a-zA-Z_]*)
*(.bss..L*)
@@ -59,11 +57,7 @@ SECTIONS {
*(.rodata .rodata.[0-9a-zA-Z_]*)
*(.rodata..L*)
}
-#else
- .data : {
- MOD_CODETAG_SECTIONS()
- }
-#endif
+
MOD_SEPARATE_CODETAG_SECTIONS()
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 03/64] x86/module: Improve relocation error messages
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 01/64] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 02/64] vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 04/64] x86/kprobes: Remove STACK_FRAME_NON_STANDARD annotation Josh Poimboeuf
` (60 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add the section number and reloc index to relocation error messages to
help find the faulty relocation.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/kernel/module.c | 15 +++++++++------
kernel/livepatch/core.c | 4 ++--
2 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 0ffbae902e2f..11c45ce42694 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -97,6 +97,7 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
DEBUGP("%s relocate section %u to %u\n",
apply ? "Applying" : "Clearing",
relsec, sechdrs[relsec].sh_info);
+
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
size_t size;
@@ -162,15 +163,17 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
if (apply) {
if (memcmp(loc, &zero, size)) {
- pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
- (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+ pr_err("x86/modules: Invalid relocation target, existing value is nonzero for sec %u, idx %u, type %d, loc %lx, val %llx\n",
+ relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),
+ (unsigned long)loc, val);
return -ENOEXEC;
}
write(loc, &val, size);
} else {
if (memcmp(loc, &val, size)) {
- pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
- (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+ pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for sec %u, idx %u, type %d, loc %lx, val %llx\n",
+ relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),
+ (unsigned long)loc, val);
return -ENOEXEC;
}
write(loc, &zero, size);
@@ -179,8 +182,8 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
return 0;
overflow:
- pr_err("overflow in relocation type %d val %Lx\n",
- (int)ELF64_R_TYPE(rel[i].r_info), val);
+ pr_err("overflow in relocation type %d val %llx sec %u idx %d\n",
+ (int)ELF64_R_TYPE(rel[i].r_info), val, relsec, i);
pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
me->name);
return -ENOEXEC;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 0e73fac55f8e..7e443c2cf7d4 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -217,8 +217,8 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) {
sym = (Elf_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info);
if (sym->st_shndx != SHN_LIVEPATCH) {
- pr_err("symbol %s is not marked as a livepatch symbol\n",
- strtab + sym->st_name);
+ pr_err("symbol %s at rela sec %u idx %d is not marked as a livepatch symbol\n",
+ strtab + sym->st_name, symndx, i);
return -EINVAL;
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 04/64] x86/kprobes: Remove STACK_FRAME_NON_STANDARD annotation
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (2 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 03/64] x86/module: Improve relocation error messages Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 05/64] compiler: Tweak __UNIQUE_ID() naming Josh Poimboeuf
` (59 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Since commit 877b145f0f47 ("x86/kprobes: Move trampoline code into
RODATA"), the optprobe template code is no longer analyzed by objtool so
it doesn't need to be ignored.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/kernel/kprobes/opt.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 0aabd4c4e2c4..6f826a00eca2 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -103,7 +103,6 @@ static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
asm (
".pushsection .rodata\n"
- "optprobe_template_func:\n"
".global optprobe_template_entry\n"
"optprobe_template_entry:\n"
#ifdef CONFIG_X86_64
@@ -160,9 +159,6 @@ asm (
"optprobe_template_end:\n"
".popsection\n");
-void optprobe_template_func(void);
-STACK_FRAME_NON_STANDARD(optprobe_template_func);
-
#define TMPL_CLAC_IDX \
((long)optprobe_template_clac - (long)optprobe_template_entry)
#define TMPL_MOVE_IDX \
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 05/64] compiler: Tweak __UNIQUE_ID() naming
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (3 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 04/64] x86/kprobes: Remove STACK_FRAME_NON_STANDARD annotation Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 06/64] compiler.h: Make addressable symbols less of an eyesore Josh Poimboeuf
` (58 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, add an underscore
between the name and the counter. This will make it possible for
objtool to distinguish between the non-unique and unique parts of the
symbol name so it can properly correlate the symbols.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/linux/compiler.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 6f04a1d8c720..4406c1592d78 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -163,7 +163,11 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
__asm__ ("" : "=r" (var) : "0" (var))
#endif
-#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+/* Format: __UNIQUE_ID_<name>_<__COUNTER__> */
+#define __UNIQUE_ID(name) \
+ __PASTE(__UNIQUE_ID_, \
+ __PASTE(name, \
+ __PASTE(_, __COUNTER__)))
/**
* data_race - mark an expression as containing intentional data races
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 06/64] compiler.h: Make addressable symbols less of an eyesore
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (4 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 05/64] compiler: Tweak __UNIQUE_ID() naming Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 07/64] elfnote: Change ELFNOTE() to use __UNIQUE_ID() Josh Poimboeuf
` (57 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Avoid underscore overload by changing:
__UNIQUE_ID___addressable_loops_per_jiffy_868
to the following:
__UNIQUE_ID_addressable_loops_per_jiffy_868
This matches the format used by other __UNIQUE_ID()-generated symbols
and improves readability for those who stare at ELF symbol table dumps.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/linux/compiler.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 4406c1592d78..2039da81cf16 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -287,7 +287,7 @@ static inline void *offset_to_ptr(const int *off)
*/
#define ___ADDRESSABLE(sym, __attrs) \
static void * __used __attrs \
- __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)(uintptr_t)&sym;
+ __UNIQUE_ID(__PASTE(addressable_, sym)) = (void *)(uintptr_t)&sym;
#define __ADDRESSABLE(sym) \
___ADDRESSABLE(sym, __section(".discard.addressable"))
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 07/64] elfnote: Change ELFNOTE() to use __UNIQUE_ID()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (5 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 06/64] compiler.h: Make addressable symbols less of an eyesore Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 08/64] kbuild: Remove 'kmod_' prefix from __KBUILD_MODNAME Josh Poimboeuf
` (56 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, replace the custom
unique symbol name generation in ELFNOTE() with __UNIQUE_ID().
This standardizes the naming format for all "unique" symbols, which will
allow objtool to properly correlate them. Note this also removes the
"one ELF note per line" limitation.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/linux/elfnote.h | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/include/linux/elfnote.h b/include/linux/elfnote.h
index 69b136e4dd2b..bb3dcded055f 100644
--- a/include/linux/elfnote.h
+++ b/include/linux/elfnote.h
@@ -60,23 +60,21 @@
#else /* !__ASSEMBLER__ */
#include <uapi/linux/elf.h>
+#include <linux/compiler.h>
/*
* Use an anonymous structure which matches the shape of
* Elf{32,64}_Nhdr, but includes the name and desc data. The size and
* type of name and desc depend on the macro arguments. "name" must
- * be a literal string, and "desc" must be passed by value. You may
- * only define one note per line, since __LINE__ is used to generate
- * unique symbols.
+ * be a literal string, and "desc" must be passed by value.
*/
-#define _ELFNOTE_PASTE(a,b) a##b
-#define _ELFNOTE(size, name, unique, type, desc) \
+#define ELFNOTE(size, name, type, desc) \
static const struct { \
struct elf##size##_note _nhdr; \
unsigned char _name[sizeof(name)] \
__attribute__((aligned(sizeof(Elf##size##_Word)))); \
typeof(desc) _desc \
__attribute__((aligned(sizeof(Elf##size##_Word)))); \
- } _ELFNOTE_PASTE(_note_, unique) \
+ } __UNIQUE_ID(note) \
__used \
__attribute__((section(".note." name), \
aligned(sizeof(Elf##size##_Word)), \
@@ -89,11 +87,10 @@
name, \
desc \
}
-#define ELFNOTE(size, name, type, desc) \
- _ELFNOTE(size, name, __LINE__, type, desc)
#define ELFNOTE32(name, type, desc) ELFNOTE(32, name, type, desc)
#define ELFNOTE64(name, type, desc) ELFNOTE(64, name, type, desc)
+
#endif /* __ASSEMBLER__ */
#endif /* _LINUX_ELFNOTE_H */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 08/64] kbuild: Remove 'kmod_' prefix from __KBUILD_MODNAME
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (6 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 07/64] elfnote: Change ELFNOTE() to use __UNIQUE_ID() Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 09/64] modpost: Ignore unresolved section bounds symbols Josh Poimboeuf
` (55 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Masahiro Yamada
In preparation for the objtool klp diff subcommand, remove the arbitrary
'kmod_' prefix from __KBUILD_MODNAME and instead add it explicitly in
the __initcall_id() macro.
This change supports the standardization of "unique" symbol naming by
ensuring the non-unique portion of the name comes before the unique
part. That will enable objtool to properly correlate symbols across
builds.
Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/linux/init.h | 3 ++-
scripts/Makefile.lib | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/linux/init.h b/include/linux/init.h
index ee1309473bc6..553a62f4cff5 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -206,12 +206,13 @@ extern struct module __this_module;
/* Format: <modname>__<counter>_<line>_<fn> */
#define __initcall_id(fn) \
+ __PASTE(kmod_, \
__PASTE(__KBUILD_MODNAME, \
__PASTE(__, \
__PASTE(__COUNTER__, \
__PASTE(_, \
__PASTE(__LINE__, \
- __PASTE(_, fn))))))
+ __PASTE(_, fn)))))))
/* Format: __<prefix>__<iid><id> */
#define __initcall_name(prefix, __iid, id) \
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 1d581ba5df66..b95560266124 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -20,7 +20,7 @@ name-fix-token = $(subst $(comma),_,$(subst -,_,$1))
name-fix = $(call stringify,$(call name-fix-token,$1))
basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget))
modname_flags = -DKBUILD_MODNAME=$(call name-fix,$(modname)) \
- -D__KBUILD_MODNAME=kmod_$(call name-fix-token,$(modname))
+ -D__KBUILD_MODNAME=$(call name-fix-token,$(modname))
modfile_flags = -DKBUILD_MODFILE=$(call stringify,$(modfile))
_c_flags = $(filter-out $(CFLAGS_REMOVE_$(target-stem).o), \
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 09/64] modpost: Ignore unresolved section bounds symbols
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (7 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 08/64] kbuild: Remove 'kmod_' prefix from __KBUILD_MODNAME Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 10/64] x86/alternative: Refactor INT3 call emulation selftest Josh Poimboeuf
` (54 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Masahiro Yamada
In preparation for klp-build livepatch module creation tooling,
suppress warnings for unresolved references to linker-generated
__start_* and __stop_* section bounds symbols.
These symbols are expected to be undefined when modpost runs, as they're
created later by the linker.
Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
scripts/mod/modpost.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 5ca7c268294e..c2b2c8fa6d25 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -606,6 +606,11 @@ static int ignore_undef_symbol(struct elf_info *info, const char *symname)
strstarts(symname, "_savevr_") ||
strcmp(symname, ".TOC.") == 0)
return 1;
+
+ /* ignore linker-created section bounds variables */
+ if (strstarts(symname, "__start_") || strstarts(symname, "__stop_"))
+ return 1;
+
/* Do not ignore this symbol */
return 0;
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 10/64] x86/alternative: Refactor INT3 call emulation selftest
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (8 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 09/64] modpost: Ignore unresolved section bounds symbols Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 11/64] objtool: Make find_symbol_containing() less arbitrary Josh Poimboeuf
` (53 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The INT3 call emulation selftest is a bit fragile as it relies on the
compiler not inserting any extra instructions before the
int3_selftest_ip() definition.
Also, the int3_selftest_ip() symbol overlaps with the int3_selftest
symbol(), which can confuse objtool.
Fix those issues by slightly reworking the functionality and moving
int3_selftest_ip() to a separate asm function. While at it, improve the
naming.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/kernel/alternative.c | 51 +++++++++++++++++++----------------
1 file changed, 28 insertions(+), 23 deletions(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index ea1d984166cd..bacd6c157626 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2223,21 +2223,34 @@ int alternatives_text_reserved(void *start, void *end)
* See entry_{32,64}.S for more details.
*/
-/*
- * We define the int3_magic() function in assembly to control the calling
- * convention such that we can 'call' it from assembly.
- */
-
-extern void int3_magic(unsigned int *ptr); /* defined in asm */
+extern void int3_selftest_asm(unsigned int *ptr);
asm (
" .pushsection .init.text, \"ax\", @progbits\n"
-" .type int3_magic, @function\n"
-"int3_magic:\n"
+" .type int3_selftest_asm, @function\n"
+"int3_selftest_asm:\n"
ANNOTATE_NOENDBR
-" movl $1, (%" _ASM_ARG1 ")\n"
+ /*
+ * INT3 padded with NOP to CALL_INSN_SIZE. The INT3 triggers an
+ * exception, then the int3_exception_nb notifier emulates a call to
+ * int3_selftest_callee().
+ */
+" int3; nop; nop; nop; nop\n"
ASM_RET
-" .size int3_magic, .-int3_magic\n"
+" .size int3_selftest_asm, . - int3_selftest_asm\n"
+" .popsection\n"
+);
+
+extern void int3_selftest_callee(unsigned int *ptr);
+
+asm (
+" .pushsection .init.text, \"ax\", @progbits\n"
+" .type int3_selftest_callee, @function\n"
+"int3_selftest_callee:\n"
+ ANNOTATE_NOENDBR
+" movl $0x1234, (%" _ASM_ARG1 ")\n"
+ ASM_RET
+" .size int3_selftest_callee, . - int3_selftest_callee\n"
" .popsection\n"
);
@@ -2246,7 +2259,7 @@ extern void int3_selftest_ip(void); /* defined in asm below */
static int __init
int3_exception_notify(struct notifier_block *self, unsigned long val, void *data)
{
- unsigned long selftest = (unsigned long)&int3_selftest_ip;
+ unsigned long selftest = (unsigned long)&int3_selftest_asm;
struct die_args *args = data;
struct pt_regs *regs = args->regs;
@@ -2261,7 +2274,7 @@ int3_exception_notify(struct notifier_block *self, unsigned long val, void *data
if (regs->ip - INT3_INSN_SIZE != selftest)
return NOTIFY_DONE;
- int3_emulate_call(regs, (unsigned long)&int3_magic);
+ int3_emulate_call(regs, (unsigned long)&int3_selftest_callee);
return NOTIFY_STOP;
}
@@ -2277,19 +2290,11 @@ static noinline void __init int3_selftest(void)
BUG_ON(register_die_notifier(&int3_exception_nb));
/*
- * Basically: int3_magic(&val); but really complicated :-)
- *
- * INT3 padded with NOP to CALL_INSN_SIZE. The int3_exception_nb
- * notifier above will emulate CALL for us.
+ * Basically: int3_selftest_callee(&val); but really complicated :-)
*/
- asm volatile ("int3_selftest_ip:\n\t"
- ANNOTATE_NOENDBR
- " int3; nop; nop; nop; nop\n\t"
- : ASM_CALL_CONSTRAINT
- : __ASM_SEL_RAW(a, D) (&val)
- : "memory");
+ int3_selftest_asm(&val);
- BUG_ON(val != 1);
+ BUG_ON(val != 0x1234);
unregister_die_notifier(&int3_exception_nb);
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 11/64] objtool: Make find_symbol_containing() less arbitrary
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (9 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 10/64] x86/alternative: Refactor INT3 call emulation selftest Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 12/64] objtool: Fix broken error handling in read_symbols() Josh Poimboeuf
` (52 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In the rare case of overlapping symbols, find_symbol_containing() just
returns the first one it finds. Make it slightly less arbitrary by
returning the smallest symbol with size > 0.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index ca5d77db692a..1c1bb2cb960d 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -193,14 +193,29 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
{
struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
- struct symbol *iter;
+ struct symbol *sym = NULL, *tmp;
- __sym_for_each(iter, tree, offset, offset) {
- if (iter->type != STT_SECTION)
- return iter;
+ __sym_for_each(tmp, tree, offset, offset) {
+ if (tmp->len) {
+ if (!sym) {
+ sym = tmp;
+ continue;
+ }
+
+ if (sym->offset != tmp->offset || sym->len != tmp->len) {
+ /*
+ * In the rare case of overlapping symbols,
+ * pick the smaller one.
+ *
+ * TODO: outlaw overlapping symbols
+ */
+ if (tmp->len < sym->len)
+ sym = tmp;
+ }
+ }
}
- return NULL;
+ return sym;
}
/*
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 12/64] objtool: Fix broken error handling in read_symbols()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (10 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 11/64] objtool: Make find_symbol_containing() less arbitrary Josh Poimboeuf
@ 2025-06-26 23:54 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 13/64] objtool: Propagate elf_truncate_section() error in elf_write() Josh Poimboeuf
` (51 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:54 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The free(sym) call in the read_symbols() error path is fundamentally
broken: 'sym' doesn't point to any allocated block. If triggered,
things would go from bad to worse.
Remove the free() and simplify the error paths. Freeing memory isn't
necessary here anyway, these are fatal errors which lead to an immediate
exit().
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 1c1bb2cb960d..b009d9feed76 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -492,14 +492,14 @@ static int read_symbols(struct elf *elf)
if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
&shndx)) {
ERROR_ELF("gelf_getsymshndx");
- goto err;
+ return -1;
}
sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
sym->sym.st_name);
if (!sym->name) {
ERROR_ELF("elf_strptr");
- goto err;
+ return -1;
}
if ((sym->sym.st_shndx > SHN_UNDEF &&
@@ -511,7 +511,7 @@ static int read_symbols(struct elf *elf)
sym->sec = find_section_by_index(elf, shndx);
if (!sym->sec) {
ERROR("couldn't find section for symbol %s", sym->name);
- goto err;
+ return -1;
}
if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
sym->name = sym->sec->name;
@@ -581,10 +581,6 @@ static int read_symbols(struct elf *elf)
}
return 0;
-
-err:
- free(sym);
- return -1;
}
static int mark_group_syms(struct elf *elf)
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 13/64] objtool: Propagate elf_truncate_section() error in elf_write()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (11 preceding siblings ...)
2025-06-26 23:54 ` [PATCH v3 12/64] objtool: Fix broken error handling in read_symbols() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 14/64] objtool: Remove error handling boilerplate Josh Poimboeuf
` (50 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Properly check and propagate the return value of elf_truncate_section()
to avoid silent failures.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index b009d9feed76..19e249f4783c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -1307,7 +1307,6 @@ static int elf_truncate_section(struct elf *elf, struct section *sec)
for (;;) {
/* get next data descriptor for the relevant section */
data = elf_getdata(s, data);
-
if (!data) {
if (size) {
ERROR("end of section data but non-zero size left\n");
@@ -1343,8 +1342,8 @@ int elf_write(struct elf *elf)
/* Update changed relocation sections and section headers: */
list_for_each_entry(sec, &elf->sections, list) {
- if (sec->truncate)
- elf_truncate_section(elf, sec);
+ if (sec->truncate && elf_truncate_section(elf, sec))
+ return -1;
if (sec_changed(sec)) {
s = elf_getscn(elf->elf, sec->idx);
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 14/64] objtool: Remove error handling boilerplate
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (12 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 13/64] objtool: Propagate elf_truncate_section() error in elf_write() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 15/64] objtool: Add empty symbols to the symbol tree again Josh Poimboeuf
` (49 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Up to a certain point in objtool's execution, all errors are fatal and
return -1. When propagating such errors, just return -1 directly
instead of trying to propagate the original return code. This helps
make the code more compact and the behavior more explicit.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 151 +++++++++++++++-------------------------
tools/objtool/special.c | 9 +--
2 files changed, 59 insertions(+), 101 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index f23bdda737aa..096bb603a67f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -429,7 +429,6 @@ static int decode_instructions(struct objtool_file *file)
struct symbol *func;
unsigned long offset;
struct instruction *insn;
- int ret;
for_each_sec(file, sec) {
struct instruction *insns = NULL;
@@ -478,11 +477,8 @@ static int decode_instructions(struct objtool_file *file)
insn->offset = offset;
insn->prev_len = prev_len;
- ret = arch_decode_instruction(file, sec, offset,
- sec->sh.sh_size - offset,
- insn);
- if (ret)
- return ret;
+ if (arch_decode_instruction(file, sec, offset, sec->sh.sh_size - offset, insn))
+ return -1;
prev_len = insn->len;
@@ -598,7 +594,7 @@ static int init_pv_ops(struct objtool_file *file)
};
const char *pv_ops;
struct symbol *sym;
- int idx, nr, ret;
+ int idx, nr;
if (!opts.noinstr)
return 0;
@@ -620,9 +616,8 @@ static int init_pv_ops(struct objtool_file *file)
INIT_LIST_HEAD(&file->pv_ops[idx].targets);
for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++) {
- ret = add_pv_ops(file, pv_ops);
- if (ret)
- return ret;
+ if (add_pv_ops(file, pv_ops))
+ return -1;
}
return 0;
@@ -1483,7 +1478,6 @@ static int add_jump_destinations(struct objtool_file *file)
struct reloc *reloc;
struct section *dest_sec;
unsigned long dest_off;
- int ret;
for_each_insn(file, insn) {
struct symbol *func = insn_func(insn);
@@ -1506,9 +1500,8 @@ static int add_jump_destinations(struct objtool_file *file)
dest_sec = reloc->sym->sec;
dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
} else if (reloc->sym->retpoline_thunk) {
- ret = add_retpoline_call(file, insn);
- if (ret)
- return ret;
+ if (add_retpoline_call(file, insn))
+ return -1;
continue;
} else if (reloc->sym->return_thunk) {
add_return_call(file, insn, true);
@@ -1518,9 +1511,8 @@ static int add_jump_destinations(struct objtool_file *file)
* External sibling call or internal sibling call with
* STT_FUNC reloc.
*/
- ret = add_call_dest(file, insn, reloc->sym, true);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, reloc->sym, true))
+ return -1;
continue;
} else if (reloc->sym->sec->idx) {
dest_sec = reloc->sym->sec;
@@ -1569,9 +1561,8 @@ static int add_jump_destinations(struct objtool_file *file)
*/
if (jump_dest->sym && jump_dest->offset == jump_dest->sym->offset) {
if (jump_dest->sym->retpoline_thunk) {
- ret = add_retpoline_call(file, insn);
- if (ret)
- return ret;
+ if (add_retpoline_call(file, insn))
+ return -1;
continue;
}
if (jump_dest->sym->return_thunk) {
@@ -1612,9 +1603,8 @@ static int add_jump_destinations(struct objtool_file *file)
* Internal sibling call without reloc or with
* STT_SECTION reloc.
*/
- ret = add_call_dest(file, insn, insn_func(jump_dest), true);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, insn_func(jump_dest), true))
+ return -1;
continue;
}
@@ -1644,7 +1634,6 @@ static int add_call_destinations(struct objtool_file *file)
unsigned long dest_off;
struct symbol *dest;
struct reloc *reloc;
- int ret;
for_each_insn(file, insn) {
struct symbol *func = insn_func(insn);
@@ -1656,9 +1645,8 @@ static int add_call_destinations(struct objtool_file *file)
dest_off = arch_jump_destination(insn);
dest = find_call_destination(insn->sec, dest_off);
- ret = add_call_dest(file, insn, dest, false);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, dest, false))
+ return -1;
if (func && func->ignore)
continue;
@@ -1682,19 +1670,16 @@ static int add_call_destinations(struct objtool_file *file)
return -1;
}
- ret = add_call_dest(file, insn, dest, false);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, dest, false))
+ return -1;
} else if (reloc->sym->retpoline_thunk) {
- ret = add_retpoline_call(file, insn);
- if (ret)
- return ret;
+ if (add_retpoline_call(file, insn))
+ return -1;
} else {
- ret = add_call_dest(file, insn, reloc->sym, false);
- if (ret)
- return ret;
+ if (add_call_dest(file, insn, reloc->sym, false))
+ return -1;
}
}
@@ -1911,7 +1896,6 @@ static int add_special_section_alts(struct objtool_file *file)
struct instruction *orig_insn, *new_insn;
struct special_alt *special_alt, *tmp;
struct alternative *alt;
- int ret;
if (special_get_alts(file->elf, &special_alts))
return -1;
@@ -1943,16 +1927,12 @@ static int add_special_section_alts(struct objtool_file *file)
continue;
}
- ret = handle_group_alt(file, special_alt, orig_insn,
- &new_insn);
- if (ret)
- return ret;
+ if (handle_group_alt(file, special_alt, orig_insn, &new_insn))
+ return -1;
} else if (special_alt->jump_or_nop) {
- ret = handle_jump_alt(file, special_alt, orig_insn,
- &new_insn);
- if (ret)
- return ret;
+ if (handle_jump_alt(file, special_alt, orig_insn, &new_insn))
+ return -1;
}
alt = calloc(1, sizeof(*alt));
@@ -2140,15 +2120,13 @@ static int add_func_jump_tables(struct objtool_file *file,
struct symbol *func)
{
struct instruction *insn;
- int ret;
func_for_each_insn(file, func, insn) {
if (!insn_jump_table(insn))
continue;
- ret = add_jump_table(file, insn);
- if (ret)
- return ret;
+ if (add_jump_table(file, insn))
+ return -1;
}
return 0;
@@ -2162,7 +2140,6 @@ static int add_func_jump_tables(struct objtool_file *file,
static int add_jump_table_alts(struct objtool_file *file)
{
struct symbol *func;
- int ret;
if (!file->rodata)
return 0;
@@ -2172,9 +2149,8 @@ static int add_jump_table_alts(struct objtool_file *file)
continue;
mark_func_jump_tables(file, func);
- ret = add_func_jump_tables(file, func);
- if (ret)
- return ret;
+ if (add_func_jump_tables(file, func))
+ return -1;
}
return 0;
@@ -2298,7 +2274,7 @@ static int read_annotate(struct objtool_file *file,
struct instruction *insn;
struct reloc *reloc;
uint64_t offset;
- int type, ret;
+ int type;
sec = find_section_by_name(file->elf, ".discard.annotate_insn");
if (!sec)
@@ -2327,9 +2303,8 @@ static int read_annotate(struct objtool_file *file,
return -1;
}
- ret = func(file, type, insn);
- if (ret < 0)
- return ret;
+ if (func(file, type, insn))
+ return -1;
}
return 0;
@@ -2527,76 +2502,62 @@ static void mark_rodata(struct objtool_file *file)
static int decode_sections(struct objtool_file *file)
{
- int ret;
-
mark_rodata(file);
- ret = init_pv_ops(file);
- if (ret)
- return ret;
+ if (init_pv_ops(file))
+ return -1;
/*
* Must be before add_{jump_call}_destination.
*/
- ret = classify_symbols(file);
- if (ret)
- return ret;
+ if (classify_symbols(file))
+ return -1;
- ret = decode_instructions(file);
- if (ret)
- return ret;
+ if (decode_instructions(file))
+ return -1;
- ret = add_ignores(file);
- if (ret)
- return ret;
+ if (add_ignores(file))
+ return -1;
add_uaccess_safe(file);
- ret = read_annotate(file, __annotate_early);
- if (ret)
- return ret;
+ if (read_annotate(file, __annotate_early))
+ return -1;
/*
* Must be before add_jump_destinations(), which depends on 'func'
* being set for alternatives, to enable proper sibling call detection.
*/
if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
- ret = add_special_section_alts(file);
- if (ret)
- return ret;
+ if (add_special_section_alts(file))
+ return -1;
}
- ret = add_jump_destinations(file);
- if (ret)
- return ret;
+ if (add_jump_destinations(file))
+ return -1;
/*
* Must be before add_call_destination(); it changes INSN_CALL to
* INSN_JUMP.
*/
- ret = read_annotate(file, __annotate_ifc);
- if (ret)
- return ret;
+ if (read_annotate(file, __annotate_ifc))
+ return -1;
- ret = add_call_destinations(file);
- if (ret)
- return ret;
+ if (add_call_destinations(file))
+ return -1;
- ret = add_jump_table_alts(file);
- if (ret)
- return ret;
+ if (add_jump_table_alts(file))
+ return -1;
- ret = read_unwind_hints(file);
- if (ret)
- return ret;
+ if (read_unwind_hints(file))
+ return -1;
/*
* Must be after add_call_destinations() such that it can override
* dead_end_function() marks.
*/
- ret = read_annotate(file, __annotate_late);
- if (ret)
- return ret;
+ if (read_annotate(file, __annotate_late))
+ return -1;
return 0;
}
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index c80fed8a840e..c0beefb93b62 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -133,7 +133,7 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
struct section *sec;
unsigned int nr_entries;
struct special_alt *alt;
- int idx, ret;
+ int idx;
INIT_LIST_HEAD(alts);
@@ -157,11 +157,8 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
}
memset(alt, 0, sizeof(*alt));
- ret = get_alt_entry(elf, entry, sec, idx, alt);
- if (ret > 0)
- continue;
- if (ret < 0)
- return ret;
+ if (get_alt_entry(elf, entry, sec, idx, alt))
+ return -1;
list_add_tail(&alt->list, alts);
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 15/64] objtool: Add empty symbols to the symbol tree again
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (13 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 14/64] objtool: Remove error handling boilerplate Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 16/64] objtool: Fix interval tree insertion for zero-length symbols Josh Poimboeuf
` (48 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The following commit
5da6aea375cd ("objtool: Fix find_{symbol,func}_containing()")
fixed the issue where overlapping symbols weren't getting sorted
properly in the symbol tree. Therefore the workaround to skip adding
empty symbols from the following commit
a2e38dffcd93 ("objtool: Don't add empty symbols to the rbtree")
is no longer needed.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 19e249f4783c..a8a78b55d3ec 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -96,7 +96,8 @@ static inline unsigned long __sym_last(struct symbol *s)
}
INTERVAL_TREE_DEFINE(struct symbol, node, unsigned long, __subtree_last,
- __sym_start, __sym_last, static, __sym)
+ __sym_start, __sym_last, static inline __maybe_unused,
+ __sym)
#define __sym_for_each(_iter, _tree, _start, _end) \
for (_iter = __sym_iter_first((_tree), (_start), (_end)); \
@@ -440,13 +441,6 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
list_add(&sym->list, entry);
elf_hash_add(symbol, &sym->hash, sym->idx);
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
-
- /*
- * Don't store empty STT_NOTYPE symbols in the rbtree. They
- * can exist within a function, confusing the sorting.
- */
- if (!sym->len)
- __sym_remove(sym, &sym->sec->symbol_tree);
}
static int read_symbols(struct elf *elf)
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 16/64] objtool: Fix interval tree insertion for zero-length symbols
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (14 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 15/64] objtool: Add empty symbols to the symbol tree again Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 17/64] objtool: Fix weak symbol detection Josh Poimboeuf
` (47 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Zero-length symbols get inserted in the wrong spot. Fix that.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index a8a78b55d3ec..c024937eb12a 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -92,7 +92,7 @@ static inline unsigned long __sym_start(struct symbol *s)
static inline unsigned long __sym_last(struct symbol *s)
{
- return s->offset + s->len - 1;
+ return s->offset + (s->len ? s->len - 1 : 0);
}
INTERVAL_TREE_DEFINE(struct symbol, node, unsigned long, __subtree_last,
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 17/64] objtool: Fix weak symbol detection
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (15 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 16/64] objtool: Fix interval tree insertion for zero-length symbols Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-27 9:13 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 18/64] objtool: Fix x86 addend calculation Josh Poimboeuf
` (46 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
find_symbol_hole_containing() fails to find a symbol hole (aka stripped
weak symbol) if its section has no symbols before the hole. This breaks
weak symbol detection if -ffunction-sections is enabled.
Fix that by allowing the interval tree to contain section symbols, which
are always at offset zero for a given section.
Fixes a bunch of (-ffunction-sections) warnings like:
vmlinux.o: warning: objtool: .text.__x64_sys_io_setup+0x10: unreachable instruction
Fixes: 4adb23686795 ("objtool: Ignore extra-symbol code")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/include/linux/interval_tree_generic.h | 2 +-
tools/objtool/elf.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/tools/include/linux/interval_tree_generic.h b/tools/include/linux/interval_tree_generic.h
index aaa8a0767aa3..c0ec9dbdfbaf 100644
--- a/tools/include/linux/interval_tree_generic.h
+++ b/tools/include/linux/interval_tree_generic.h
@@ -77,7 +77,7 @@ ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, \
* Cond2: start <= ITLAST(node) \
*/ \
\
-static ITSTRUCT * \
+ITSTATIC ITSTRUCT * \
ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
{ \
while (true) { \
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index c024937eb12a..d7fb3d0b05cf 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -109,7 +109,7 @@ struct symbol_hole {
};
/*
- * Find !section symbol where @offset is after it.
+ * Find the last symbol before @offset.
*/
static int symbol_hole_by_offset(const void *key, const struct rb_node *node)
{
@@ -120,8 +120,7 @@ static int symbol_hole_by_offset(const void *key, const struct rb_node *node)
return -1;
if (sh->key >= s->offset + s->len) {
- if (s->type != STT_SECTION)
- sh->sym = s;
+ sh->sym = s;
return 1;
}
@@ -428,7 +427,8 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
sym->len = sym->sym.st_size;
__sym_for_each(iter, &sym->sec->symbol_tree, sym->offset, sym->offset) {
- if (iter->offset == sym->offset && iter->type == sym->type)
+ if (iter->offset == sym->offset && iter->type == sym->type &&
+ iter->len == sym->len)
iter->alias = sym;
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 18/64] objtool: Fix x86 addend calculation
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (16 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 17/64] objtool: Fix weak symbol detection Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 19/64] objtool: Fix __pa_symbol() relocation handling Josh Poimboeuf
` (45 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On x86, arch_dest_reloc_offset() hardcodes the addend adjustment to
four, but the actual adjustment depends on the relocation type. Fix
that.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/arch/loongarch/decode.c | 4 ++--
tools/objtool/arch/powerpc/decode.c | 4 ++--
tools/objtool/arch/x86/decode.c | 9 +++++++--
tools/objtool/check.c | 15 +++++----------
tools/objtool/include/objtool/arch.h | 2 +-
5 files changed, 17 insertions(+), 17 deletions(-)
diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index b6fdc68053cc..330671d88c59 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -17,9 +17,9 @@ unsigned long arch_jump_destination(struct instruction *insn)
return insn->offset + (insn->immediate << 2);
}
-unsigned long arch_dest_reloc_offset(int addend)
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
{
- return addend;
+ return reloc_addend(reloc);
}
bool arch_pc_relative_reloc(struct reloc *reloc)
diff --git a/tools/objtool/arch/powerpc/decode.c b/tools/objtool/arch/powerpc/decode.c
index c851c51d4bd3..9b17885e6cba 100644
--- a/tools/objtool/arch/powerpc/decode.c
+++ b/tools/objtool/arch/powerpc/decode.c
@@ -14,9 +14,9 @@ int arch_ftrace_match(char *name)
return !strcmp(name, "_mcount");
}
-unsigned long arch_dest_reloc_offset(int addend)
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
{
- return addend;
+ return reloc_addend(reloc);
}
bool arch_callee_saved_reg(unsigned char reg)
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 98c4713c1b09..f29ab0f3d4a7 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -68,9 +68,14 @@ bool arch_callee_saved_reg(unsigned char reg)
}
}
-unsigned long arch_dest_reloc_offset(int addend)
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
{
- return addend + 4;
+ s64 addend = reloc_addend(reloc);
+
+ if (arch_pc_relative_reloc(reloc))
+ addend += insn->offset + insn->len - reloc_offset(reloc);
+
+ return addend;
}
unsigned long arch_jump_destination(struct instruction *insn)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 096bb603a67f..fd93cae8b1b9 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1498,7 +1498,7 @@ static int add_jump_destinations(struct objtool_file *file)
dest_off = arch_jump_destination(insn);
} else if (reloc->sym->type == STT_SECTION) {
dest_sec = reloc->sym->sec;
- dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
+ dest_off = arch_insn_adjusted_addend(insn, reloc);
} else if (reloc->sym->retpoline_thunk) {
if (add_retpoline_call(file, insn))
return -1;
@@ -1517,7 +1517,7 @@ static int add_jump_destinations(struct objtool_file *file)
} else if (reloc->sym->sec->idx) {
dest_sec = reloc->sym->sec;
dest_off = reloc->sym->sym.st_value +
- arch_dest_reloc_offset(reloc_addend(reloc));
+ arch_insn_adjusted_addend(insn, reloc);
} else {
/* non-func asm code jumping to another file */
continue;
@@ -1662,7 +1662,7 @@ static int add_call_destinations(struct objtool_file *file)
}
} else if (reloc->sym->type == STT_SECTION) {
- dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
+ dest_off = arch_insn_adjusted_addend(insn, reloc);
dest = find_call_destination(reloc->sym->sec, dest_off);
if (!dest) {
ERROR_INSN(insn, "can't find call dest symbol at %s+0x%lx",
@@ -3311,7 +3311,7 @@ static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
if (!reloc || strcmp(reloc->sym->name, "pv_ops"))
return false;
- idx = (arch_dest_reloc_offset(reloc_addend(reloc)) / sizeof(void *));
+ idx = arch_insn_adjusted_addend(insn, reloc) / sizeof(void *);
if (file->pv_ops[idx].clean)
return true;
@@ -4359,12 +4359,7 @@ static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn
reloc_offset(reloc) + 1,
(insn->offset + insn->len) - (reloc_offset(reloc) + 1))) {
- off = reloc->sym->offset;
- if (reloc_type(reloc) == R_X86_64_PC32 ||
- reloc_type(reloc) == R_X86_64_PLT32)
- off += arch_dest_reloc_offset(reloc_addend(reloc));
- else
- off += reloc_addend(reloc);
+ off = reloc->sym->offset + arch_insn_adjusted_addend(insn, reloc);
dest = find_insn(file, reloc->sym->sec, off);
if (!dest)
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index 01ef6f415adf..cd1776c35b13 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -83,7 +83,7 @@ bool arch_callee_saved_reg(unsigned char reg);
unsigned long arch_jump_destination(struct instruction *insn);
-unsigned long arch_dest_reloc_offset(int addend);
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc);
const char *arch_nop_insn(int len);
const char *arch_ret_insn(int len);
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 19/64] objtool: Fix __pa_symbol() relocation handling
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (17 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 18/64] objtool: Fix x86 addend calculation Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 20/64] objtool: Fix "unexpected end of section" warning for alternatives Josh Poimboeuf
` (44 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
__pa_symbol() generates a relocation which refers to a physical address.
Convert it to back its virtual form before calculating the addend.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/arch/x86/decode.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index f29ab0f3d4a7..b10cfa9cd71e 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -68,6 +68,17 @@ bool arch_callee_saved_reg(unsigned char reg)
}
}
+/* Undo the effects of __pa_symbol() if necessary */
+static unsigned long phys_to_virt(unsigned long pa)
+{
+ s64 va = pa;
+
+ if (va > 0)
+ va &= ~(0x80000000);
+
+ return va;
+}
+
s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
{
s64 addend = reloc_addend(reloc);
@@ -75,7 +86,7 @@ s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
if (arch_pc_relative_reloc(reloc))
addend += insn->offset + insn->len - reloc_offset(reloc);
- return addend;
+ return phys_to_virt(addend);
}
unsigned long arch_jump_destination(struct instruction *insn)
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 20/64] objtool: Fix "unexpected end of section" warning for alternatives
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (18 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 19/64] objtool: Fix __pa_symbol() relocation handling Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 21/64] objtool: Check for missing annotation entries in read_annotate() Josh Poimboeuf
` (43 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Due to the short circuiting logic in next_insn_to_validate(), control
flow may silently transition from .altinstr_replacement to .text without
a corresponding nested call to validate_branch().
As a result the validate_branch() 'sec' variable doesn't get
reinitialized, which can trigger a confusing "unexpected end of section"
warning which blames .altinstr_replacement rather than the offending
fallthrough function.
Fix that by not caching the section. There's no point in doing that
anyway.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index fd93cae8b1b9..b5257a959458 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3508,15 +3508,12 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
{
struct alternative *alt;
struct instruction *next_insn, *prev_insn = NULL;
- struct section *sec;
u8 visited;
int ret;
if (func && func->ignore)
return 0;
- sec = insn->sec;
-
while (1) {
next_insn = next_insn_to_validate(file, insn);
@@ -3754,7 +3751,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
WARN("%s%sunexpected end of section %s",
func ? func->name : "", func ? "(): " : "",
- sec->name);
+ insn->sec->name);
return 1;
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 21/64] objtool: Check for missing annotation entries in read_annotate()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (19 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 20/64] objtool: Fix "unexpected end of section" warning for alternatives Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 22/64] objtool: Const string cleanup Josh Poimboeuf
` (42 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a sanity check to make sure none of the relocations for the
.discard.annotate_insn section have gone missing.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b5257a959458..fe18f9f5dbef 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2292,6 +2292,11 @@ static int read_annotate(struct objtool_file *file,
sec->sh.sh_entsize = 8;
}
+ if (sec_num_entries(sec) != sec_num_entries(sec->rsec)) {
+ ERROR("bad .discard.annotate_insn section: missing relocs");
+ return -1;
+ }
+
for_each_reloc(sec->rsec, reloc) {
type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4);
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 22/64] objtool: Const string cleanup
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (20 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 21/64] objtool: Check for missing annotation entries in read_annotate() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 23/64] objtool: Clean up compiler flag usage Josh Poimboeuf
` (41 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Use 'const char *' where applicable.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/arch/loongarch/decode.c | 2 +-
tools/objtool/arch/powerpc/decode.c | 2 +-
tools/objtool/arch/x86/decode.c | 2 +-
tools/objtool/elf.c | 6 +++---
tools/objtool/include/objtool/arch.h | 2 +-
tools/objtool/include/objtool/elf.h | 6 +++---
6 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index 330671d88c59..7b38718d782a 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -7,7 +7,7 @@
#include <linux/objtool_types.h>
#include <arch/elf.h>
-int arch_ftrace_match(char *name)
+int arch_ftrace_match(const char *name)
{
return !strcmp(name, "_mcount");
}
diff --git a/tools/objtool/arch/powerpc/decode.c b/tools/objtool/arch/powerpc/decode.c
index 9b17885e6cba..d4cb02120a6b 100644
--- a/tools/objtool/arch/powerpc/decode.c
+++ b/tools/objtool/arch/powerpc/decode.c
@@ -9,7 +9,7 @@
#include <objtool/builtin.h>
#include <objtool/endianness.h>
-int arch_ftrace_match(char *name)
+int arch_ftrace_match(const char *name)
{
return !strcmp(name, "_mcount");
}
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index b10cfa9cd71e..36a65cecada3 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -23,7 +23,7 @@
#include <objtool/builtin.h>
#include <arch/elf.h>
-int arch_ftrace_match(char *name)
+int arch_ftrace_match(const char *name)
{
return !strcmp(name, "__fentry__");
}
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d7fb3d0b05cf..2ea6d591c3c2 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -853,7 +853,7 @@ elf_create_section_symbol(struct elf *elf, struct section *sec)
return sym;
}
-static int elf_add_string(struct elf *elf, struct section *strtab, char *str);
+static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
struct symbol *
elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size)
@@ -1086,7 +1086,7 @@ struct elf *elf_open_read(const char *name, int flags)
return NULL;
}
-static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
+static int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
{
Elf_Data *data;
Elf_Scn *s;
@@ -1111,7 +1111,7 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
return -1;
}
- data->d_buf = str;
+ data->d_buf = strdup(str);
data->d_size = strlen(str) + 1;
data->d_align = 1;
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index cd1776c35b13..07729a240159 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -71,7 +71,7 @@ struct stack_op {
struct instruction;
-int arch_ftrace_match(char *name);
+int arch_ftrace_match(const char *name);
void arch_initial_func_cfi_state(struct cfi_init_state *state);
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 0a2fa3ac0079..0f9adfe8e852 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -40,7 +40,7 @@ struct section {
struct section *base, *rsec;
struct symbol *sym;
Elf_Data *data;
- char *name;
+ const char *name;
int idx;
bool _changed, text, rodata, noinstr, init, truncate;
struct reloc *relocs;
@@ -53,7 +53,7 @@ struct symbol {
struct elf_hash_node name_hash;
GElf_Sym sym;
struct section *sec;
- char *name;
+ const char *name;
unsigned int idx, len;
unsigned long offset;
unsigned long __subtree_last;
@@ -87,7 +87,7 @@ struct elf {
GElf_Ehdr ehdr;
int fd;
bool changed;
- char *name;
+ const char *name;
unsigned int num_files;
struct list_head sections;
unsigned long num_relocs;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 23/64] objtool: Clean up compiler flag usage
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (21 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 22/64] objtool: Const string cleanup Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 24/64] objtool: Remove .parainstructions reference Josh Poimboeuf
` (40 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
KBUILD_HOSTCFLAGS and KBUILD_HOSTLDFLAGS aren't defined when objtool is
built standalone. Also, the EXTRA_WARNINGS flags are rather arbitrary.
Make things simpler and more consistent by specifying compiler flags
explicitly and tweaking the warnings. Also make a few code tweaks to
make the new warnings happy.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/Makefile | 15 ++++++++++-----
tools/objtool/check.c | 4 ++--
tools/objtool/elf.c | 2 +-
3 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 8c20361dd100..fc82d47f2b9a 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -23,6 +23,11 @@ LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lel
all: $(OBJTOOL)
+WARNINGS := -Werror -Wall -Wextra -Wmissing-prototypes \
+ -Wmissing-declarations -Wwrite-strings \
+ -Wno-implicit-fallthrough -Wno-sign-compare \
+ -Wno-unused-parameter
+
INCLUDES := -I$(srctree)/tools/include \
-I$(srctree)/tools/include/uapi \
-I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
@@ -30,11 +35,11 @@ INCLUDES := -I$(srctree)/tools/include \
-I$(srctree)/tools/objtool/include \
-I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \
-I$(LIBSUBCMD_OUTPUT)/include
-# Note, EXTRA_WARNINGS here was determined for CC and not HOSTCC, it
-# is passed here to match a legacy behavior.
-WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed -Wno-nested-externs
-OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
-OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
+
+OBJTOOL_CFLAGS := -std=gnu11 -fomit-frame-pointer -O2 -g \
+ $(WARNINGS) $(INCLUDES) $(LIBELF_FLAGS) $(HOSTCFLAGS)
+
+OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(HOSTLDFLAGS)
# Allow old libelf to be used:
elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - 2>/dev/null | grep elf_getshdr)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index fe18f9f5dbef..4e779bf8fcae 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -460,7 +460,7 @@ static int decode_instructions(struct objtool_file *file)
for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
if (!insns || idx == INSN_CHUNK_MAX) {
- insns = calloc(sizeof(*insn), INSN_CHUNK_SIZE);
+ insns = calloc(INSN_CHUNK_SIZE, sizeof(*insn));
if (!insns) {
ERROR_GLIBC("calloc");
return -1;
@@ -606,7 +606,7 @@ static int init_pv_ops(struct objtool_file *file)
return 0;
nr = sym->len / sizeof(unsigned long);
- file->pv_ops = calloc(sizeof(struct pv_state), nr);
+ file->pv_ops = calloc(nr, sizeof(struct pv_state));
if (!file->pv_ops) {
ERROR_GLIBC("calloc");
return -1;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 2ea6d591c3c2..c27edeed2dd0 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -736,7 +736,7 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
}
/* setup extended section index magic and write the symbol */
- if ((shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) || is_special_shndx) {
+ if (shndx < SHN_LORESERVE || is_special_shndx) {
sym->sym.st_shndx = shndx;
if (!shndx_data)
shndx = 0;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 24/64] objtool: Remove .parainstructions reference
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (22 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 23/64] objtool: Clean up compiler flag usage Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 25/64] objtool: Convert elf iterator macros to use 'struct elf' Josh Poimboeuf
` (39 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The .parainstructions section no longer exists since the following
commit:
60bc276b129e ("x86/paravirt: Switch mixed paravirt/alternative calls to alternatives").
Remove the reference to it.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4e779bf8fcae..61e44b927b99 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4431,7 +4431,6 @@ static int validate_ibt(struct objtool_file *file)
!strcmp(sec->name, ".altinstructions") ||
!strcmp(sec->name, ".ibt_endbr_seal") ||
!strcmp(sec->name, ".orc_unwind_ip") ||
- !strcmp(sec->name, ".parainstructions") ||
!strcmp(sec->name, ".retpoline_sites") ||
!strcmp(sec->name, ".smp_locks") ||
!strcmp(sec->name, ".static_call_sites") ||
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 25/64] objtool: Convert elf iterator macros to use 'struct elf'
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (23 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 24/64] objtool: Remove .parainstructions reference Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 26/64] objtool: Add section/symbol type helpers Josh Poimboeuf
` (38 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
'struct objtool_file' is specific to the check code and doesn't belong
in the elf code which is supposed to be objtool_file-agnostic. Convert
the elf iterator macros to use 'struct elf' instead.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 22 +++++++++++-----------
tools/objtool/include/objtool/elf.h | 8 ++++----
tools/objtool/orc_gen.c | 2 +-
3 files changed, 16 insertions(+), 16 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 61e44b927b99..ec11fd29398b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -106,7 +106,7 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
#define for_each_insn(file, insn) \
for (struct section *__sec, *__fake = (struct section *)1; \
__fake; __fake = NULL) \
- for_each_sec(file, __sec) \
+ for_each_sec(file->elf, __sec) \
sec_for_each_insn(file, __sec, insn)
#define func_for_each_insn(file, func, insn) \
@@ -430,7 +430,7 @@ static int decode_instructions(struct objtool_file *file)
unsigned long offset;
struct instruction *insn;
- for_each_sec(file, sec) {
+ for_each_sec(file->elf, sec) {
struct instruction *insns = NULL;
u8 prev_len = 0;
u8 idx = 0;
@@ -856,7 +856,7 @@ static int create_cfi_sections(struct objtool_file *file)
}
idx = 0;
- for_each_sym(file, sym) {
+ for_each_sym(file->elf, sym) {
if (sym->type != STT_FUNC)
continue;
@@ -872,7 +872,7 @@ static int create_cfi_sections(struct objtool_file *file)
return -1;
idx = 0;
- for_each_sym(file, sym) {
+ for_each_sym(file->elf, sym) {
if (sym->type != STT_FUNC)
continue;
@@ -2144,7 +2144,7 @@ static int add_jump_table_alts(struct objtool_file *file)
if (!file->rodata)
return 0;
- for_each_sym(file, func) {
+ for_each_sym(file->elf, func) {
if (func->type != STT_FUNC)
continue;
@@ -2448,7 +2448,7 @@ static int classify_symbols(struct objtool_file *file)
{
struct symbol *func;
- for_each_sym(file, func) {
+ for_each_sym(file->elf, func) {
if (func->type == STT_NOTYPE && strstarts(func->name, ".L"))
func->local_label = true;
@@ -2493,7 +2493,7 @@ static void mark_rodata(struct objtool_file *file)
*
* .rodata.str1.* sections are ignored; they don't contain jump tables.
*/
- for_each_sec(file, sec) {
+ for_each_sec(file->elf, sec) {
if ((!strncmp(sec->name, ".rodata", 7) &&
!strstr(sec->name, ".str1.")) ||
!strncmp(sec->name, ".data.rel.ro", 12)) {
@@ -4141,7 +4141,7 @@ static int add_prefix_symbols(struct objtool_file *file)
struct section *sec;
struct symbol *func;
- for_each_sec(file, sec) {
+ for_each_sec(file->elf, sec) {
if (!(sec->sh.sh_flags & SHF_EXECINSTR))
continue;
@@ -4233,7 +4233,7 @@ static int validate_functions(struct objtool_file *file)
struct section *sec;
int warnings = 0;
- for_each_sec(file, sec) {
+ for_each_sec(file->elf, sec) {
if (!(sec->sh.sh_flags & SHF_EXECINSTR))
continue;
@@ -4412,7 +4412,7 @@ static int validate_ibt(struct objtool_file *file)
for_each_insn(file, insn)
warnings += validate_ibt_insn(file, insn);
- for_each_sec(file, sec) {
+ for_each_sec(file->elf, sec) {
/* Already done by validate_ibt_insn() */
if (sec->sh.sh_flags & SHF_EXECINSTR)
@@ -4573,7 +4573,7 @@ static void disas_warned_funcs(struct objtool_file *file)
struct symbol *sym;
char *funcs = NULL, *tmp;
- for_each_sym(file, sym) {
+ for_each_sym(file->elf, sym) {
if (sym->warned) {
if (!funcs) {
funcs = malloc(strlen(sym->name) + 1);
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 0f9adfe8e852..fcea9338c687 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -324,16 +324,16 @@ static inline void set_sym_next_reloc(struct reloc *reloc, struct reloc *next)
reloc->_sym_next_reloc = (unsigned long)next | bit;
}
-#define for_each_sec(file, sec) \
- list_for_each_entry(sec, &file->elf->sections, list)
+#define for_each_sec(elf, sec) \
+ list_for_each_entry(sec, &elf->sections, list)
#define sec_for_each_sym(sec, sym) \
list_for_each_entry(sym, &sec->symbol_list, list)
-#define for_each_sym(file, sym) \
+#define for_each_sym(elf, sym) \
for (struct section *__sec, *__fake = (struct section *)1; \
__fake; __fake = NULL) \
- for_each_sec(file, __sec) \
+ for_each_sec(elf, __sec) \
sec_for_each_sym(__sec, sym)
#define for_each_reloc(rsec, reloc) \
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 922e6aac7cea..6eff3d6a125c 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -57,7 +57,7 @@ int orc_create(struct objtool_file *file)
/* Build a deduplicated list of ORC entries: */
INIT_LIST_HEAD(&orc_list);
- for_each_sec(file, sec) {
+ for_each_sec(file->elf, sec) {
struct orc_entry orc, prev_orc = {0};
struct instruction *insn;
bool empty = true;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 26/64] objtool: Add section/symbol type helpers
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (24 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 25/64] objtool: Convert elf iterator macros to use 'struct elf' Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-27 10:29 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 27/64] objtool: Mark .cold subfunctions Josh Poimboeuf
` (37 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add some helper macros to improve readability.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/arch/x86/special.c | 2 +-
tools/objtool/check.c | 58 ++++++++++++-------------
tools/objtool/elf.c | 20 ++++-----
tools/objtool/include/objtool/elf.h | 66 +++++++++++++++++++++++++++++
tools/objtool/special.c | 4 +-
5 files changed, 108 insertions(+), 42 deletions(-)
diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
index 06ca4a2659a4..09300761f108 100644
--- a/tools/objtool/arch/x86/special.c
+++ b/tools/objtool/arch/x86/special.c
@@ -89,7 +89,7 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
/* look for a relocation which references .rodata */
text_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
insn->offset, insn->len);
- if (!text_reloc || text_reloc->sym->type != STT_SECTION ||
+ if (!text_reloc || !is_sec_sym(text_reloc->sym) ||
!text_reloc->sym->sec->rodata)
return NULL;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index ec11fd29398b..b5b324bcc9fa 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -260,7 +260,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
if (!func)
return false;
- if (func->bind == STB_GLOBAL || func->bind == STB_WEAK) {
+ if (!is_local_sym(func)) {
if (is_rust_noreturn(func))
return true;
@@ -269,7 +269,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
return true;
}
- if (func->bind == STB_WEAK)
+ if (is_weak_sym(func))
return false;
if (!func->len)
@@ -435,7 +435,7 @@ static int decode_instructions(struct objtool_file *file)
u8 prev_len = 0;
u8 idx = 0;
- if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ if (!is_text_sec(sec))
continue;
if (strcmp(sec->name, ".altinstr_replacement") &&
@@ -458,7 +458,7 @@ static int decode_instructions(struct objtool_file *file)
if (!strcmp(sec->name, ".init.text") && !opts.module)
sec->init = true;
- for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
+ for (offset = 0; offset < sec_size(sec); offset += insn->len) {
if (!insns || idx == INSN_CHUNK_MAX) {
insns = calloc(INSN_CHUNK_SIZE, sizeof(*insn));
if (!insns) {
@@ -477,7 +477,7 @@ static int decode_instructions(struct objtool_file *file)
insn->offset = offset;
insn->prev_len = prev_len;
- if (arch_decode_instruction(file, sec, offset, sec->sh.sh_size - offset, insn))
+ if (arch_decode_instruction(file, sec, offset, sec_size(sec) - offset, insn))
return -1;
prev_len = insn->len;
@@ -495,12 +495,12 @@ static int decode_instructions(struct objtool_file *file)
}
sec_for_each_sym(sec, func) {
- if (func->type != STT_NOTYPE && func->type != STT_FUNC)
+ if (!is_notype_sym(func) && !is_func_sym(func))
continue;
- if (func->offset == sec->sh.sh_size) {
+ if (func->offset == sec_size(sec)) {
/* Heuristic: likely an "end" symbol */
- if (func->type == STT_NOTYPE)
+ if (is_notype_sym(func))
continue;
ERROR("%s(): STT_FUNC at end of section", func->name);
return -1;
@@ -516,7 +516,7 @@ static int decode_instructions(struct objtool_file *file)
sym_for_each_insn(file, func, insn) {
insn->sym = func;
- if (func->type == STT_FUNC &&
+ if (is_func_sym(func) &&
insn->type == INSN_ENDBR &&
list_empty(&insn->call_node)) {
if (insn->offset == func->offset) {
@@ -560,7 +560,7 @@ static int add_pv_ops(struct objtool_file *file, const char *symname)
idx = (reloc_offset(reloc) - sym->offset) / sizeof(unsigned long);
func = reloc->sym;
- if (func->type == STT_SECTION)
+ if (is_sec_sym(func))
func = find_symbol_by_offset(reloc->sym->sec,
reloc_addend(reloc));
if (!func) {
@@ -822,7 +822,7 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
struct symbol *sym = insn->sym;
*site = 0;
- if (opts.module && sym && sym->type == STT_FUNC &&
+ if (opts.module && sym && is_func_sym(sym) &&
insn->offset == sym->offset &&
(!strcmp(sym->name, "init_module") ||
!strcmp(sym->name, "cleanup_module"))) {
@@ -857,7 +857,7 @@ static int create_cfi_sections(struct objtool_file *file)
idx = 0;
for_each_sym(file->elf, sym) {
- if (sym->type != STT_FUNC)
+ if (!is_func_sym(sym))
continue;
if (strncmp(sym->name, "__cfi_", 6))
@@ -873,7 +873,7 @@ static int create_cfi_sections(struct objtool_file *file)
idx = 0;
for_each_sym(file->elf, sym) {
- if (sym->type != STT_FUNC)
+ if (!is_func_sym(sym))
continue;
if (strncmp(sym->name, "__cfi_", 6))
@@ -1462,7 +1462,7 @@ static bool jump_is_sibling_call(struct objtool_file *file,
return false;
/* Disallow sibling calls into STT_NOTYPE */
- if (ts->type == STT_NOTYPE)
+ if (is_notype_sym(ts))
return false;
/* Must not be self to be a sibling */
@@ -1496,7 +1496,7 @@ static int add_jump_destinations(struct objtool_file *file)
if (!reloc) {
dest_sec = insn->sec;
dest_off = arch_jump_destination(insn);
- } else if (reloc->sym->type == STT_SECTION) {
+ } else if (is_sec_sym(reloc->sym)) {
dest_sec = reloc->sym->sec;
dest_off = arch_insn_adjusted_addend(insn, reloc);
} else if (reloc->sym->retpoline_thunk) {
@@ -1656,12 +1656,12 @@ static int add_call_destinations(struct objtool_file *file)
return -1;
}
- if (func && insn_call_dest(insn)->type != STT_FUNC) {
+ if (func && !is_func_sym(insn_call_dest(insn))) {
ERROR_INSN(insn, "unsupported call to non-function");
return -1;
}
- } else if (reloc->sym->type == STT_SECTION) {
+ } else if (is_sec_sym(reloc->sym)) {
dest_off = arch_insn_adjusted_addend(insn, reloc);
dest = find_call_destination(reloc->sym->sec, dest_off);
if (!dest) {
@@ -2145,7 +2145,7 @@ static int add_jump_table_alts(struct objtool_file *file)
return 0;
for_each_sym(file->elf, func) {
- if (func->type != STT_FUNC)
+ if (!is_func_sym(func))
continue;
mark_func_jump_tables(file, func);
@@ -2184,14 +2184,14 @@ static int read_unwind_hints(struct objtool_file *file)
return -1;
}
- if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
+ if (sec_size(sec) % sizeof(struct unwind_hint)) {
ERROR("struct unwind_hint size mismatch");
return -1;
}
file->hints = true;
- for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
+ for (i = 0; i < sec_size(sec) / sizeof(struct unwind_hint); i++) {
hint = (struct unwind_hint *)sec->data->d_buf + i;
reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
@@ -2200,7 +2200,7 @@ static int read_unwind_hints(struct objtool_file *file)
return -1;
}
- if (reloc->sym->type == STT_SECTION) {
+ if (is_sec_sym(reloc->sym)) {
offset = reloc_addend(reloc);
} else if (reloc->sym->local_label) {
offset = reloc->sym->offset;
@@ -2236,7 +2236,7 @@ static int read_unwind_hints(struct objtool_file *file)
if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
- if (sym && sym->bind == STB_GLOBAL) {
+ if (sym && is_global_sym(sym)) {
if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
ERROR_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
return -1;
@@ -2449,10 +2449,10 @@ static int classify_symbols(struct objtool_file *file)
struct symbol *func;
for_each_sym(file->elf, func) {
- if (func->type == STT_NOTYPE && strstarts(func->name, ".L"))
+ if (is_notype_sym(func) && strstarts(func->name, ".L"))
func->local_label = true;
- if (func->bind != STB_GLOBAL)
+ if (!is_global_sym(func))
continue;
if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
@@ -4142,11 +4142,11 @@ static int add_prefix_symbols(struct objtool_file *file)
struct symbol *func;
for_each_sec(file->elf, sec) {
- if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ if (!is_text_sec(sec))
continue;
sec_for_each_sym(sec, func) {
- if (func->type != STT_FUNC)
+ if (!is_func_sym(func))
continue;
add_prefix_symbol(file, func);
@@ -4190,7 +4190,7 @@ static int validate_section(struct objtool_file *file, struct section *sec)
int warnings = 0;
sec_for_each_sym(sec, func) {
- if (func->type != STT_FUNC)
+ if (!is_func_sym(func))
continue;
init_insn_state(file, &state, sec);
@@ -4234,7 +4234,7 @@ static int validate_functions(struct objtool_file *file)
int warnings = 0;
for_each_sec(file->elf, sec) {
- if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ if (!is_text_sec(sec))
continue;
warnings += validate_section(file, sec);
@@ -4415,7 +4415,7 @@ static int validate_ibt(struct objtool_file *file)
for_each_sec(file->elf, sec) {
/* Already done by validate_ibt_insn() */
- if (sec->sh.sh_flags & SHF_EXECINSTR)
+ if (is_text_sec(sec))
continue;
if (!sec->rsec)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index c27edeed2dd0..d36c0d42fd7b 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -170,7 +170,7 @@ struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
struct symbol *iter;
__sym_for_each(iter, tree, offset, offset) {
- if (iter->offset == offset && iter->type != STT_SECTION)
+ if (iter->offset == offset && !is_sec_sym(iter))
return iter;
}
@@ -183,7 +183,7 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
struct symbol *iter;
__sym_for_each(iter, tree, offset, offset) {
- if (iter->offset == offset && iter->type == STT_FUNC)
+ if (iter->offset == offset && is_func_sym(iter))
return iter;
}
@@ -264,7 +264,7 @@ struct symbol *find_func_containing(struct section *sec, unsigned long offset)
struct symbol *iter;
__sym_for_each(iter, tree, offset, offset) {
- if (iter->type == STT_FUNC)
+ if (is_func_sym(iter))
return iter;
}
@@ -373,14 +373,14 @@ static int read_sections(struct elf *elf)
return -1;
}
- if (sec->sh.sh_size != 0 && !is_dwarf_section(sec)) {
+ if (sec_size(sec) != 0 && !is_dwarf_section(sec)) {
sec->data = elf_getdata(s, NULL);
if (!sec->data) {
ERROR_ELF("elf_getdata");
return -1;
}
if (sec->data->d_off != 0 ||
- sec->data->d_size != sec->sh.sh_size) {
+ sec->data->d_size != sec_size(sec)) {
ERROR("unexpected data attributes for %s", sec->name);
return -1;
}
@@ -420,7 +420,7 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
sym->type = GELF_ST_TYPE(sym->sym.st_info);
sym->bind = GELF_ST_BIND(sym->sym.st_info);
- if (sym->type == STT_FILE)
+ if (is_file_sym(sym))
elf->num_files++;
sym->offset = sym->sym.st_value;
@@ -527,7 +527,7 @@ static int read_symbols(struct elf *elf)
sec_for_each_sym(sec, sym) {
char *pname;
size_t pnamelen;
- if (sym->type != STT_FUNC)
+ if (!is_func_sym(sym))
continue;
if (sym->pfunc == NULL)
@@ -929,7 +929,7 @@ struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
struct symbol *sym = insn_sec->sym;
int addend = insn_off;
- if (!(insn_sec->sh.sh_flags & SHF_EXECINSTR)) {
+ if (!is_text_sec(insn_sec)) {
ERROR("bad call to %s() for data symbol %s", __func__, sym->name);
return NULL;
}
@@ -958,7 +958,7 @@ struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
struct symbol *sym,
s64 addend)
{
- if (sym->sec && (sec->sh.sh_flags & SHF_EXECINSTR)) {
+ if (is_text_sec(sec)) {
ERROR("bad call to %s() for text symbol %s", __func__, sym->name);
return NULL;
}
@@ -1287,7 +1287,7 @@ int elf_write_insn(struct elf *elf, struct section *sec,
*/
static int elf_truncate_section(struct elf *elf, struct section *sec)
{
- u64 size = sec->sh.sh_size;
+ u64 size = sec_size(sec);
bool truncated = false;
Elf_Data *data = NULL;
Elf_Scn *s;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index fcea9338c687..0914dadece0b 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -8,6 +8,7 @@
#include <stdio.h>
#include <gelf.h>
+#include <linux/string.h>
#include <linux/list.h>
#include <linux/hashtable.h>
#include <linux/rbtree.h>
@@ -177,11 +178,71 @@ static inline unsigned int elf_text_rela_type(struct elf *elf)
return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
}
+static inline bool sym_has_sec(struct symbol *sym)
+{
+ return sym->sec->idx;
+}
+
+static inline bool is_null_sym(struct symbol *sym)
+{
+ return !sym->idx;
+}
+
+static inline bool is_sec_sym(struct symbol *sym)
+{
+ return sym->type == STT_SECTION;
+}
+
+static inline bool is_object_sym(struct symbol *sym)
+{
+ return sym->type == STT_OBJECT;
+}
+
+static inline bool is_func_sym(struct symbol *sym)
+{
+ return sym->type == STT_FUNC;
+}
+
+static inline bool is_file_sym(struct symbol *sym)
+{
+ return sym->type == STT_FILE;
+}
+
+static inline bool is_notype_sym(struct symbol *sym)
+{
+ return sym->type == STT_NOTYPE;
+}
+
+static inline bool is_global_sym(struct symbol *sym)
+{
+ return sym->bind == STB_GLOBAL;
+}
+
+static inline bool is_weak_sym(struct symbol *sym)
+{
+ return sym->bind == STB_WEAK;
+}
+
+static inline bool is_local_sym(struct symbol *sym)
+{
+ return sym->bind == STB_LOCAL;
+}
+
static inline bool is_reloc_sec(struct section *sec)
{
return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
}
+static inline bool is_string_sec(struct section *sec)
+{
+ return sec->sh.sh_flags & SHF_STRINGS;
+}
+
+static inline bool is_text_sec(struct section *sec)
+{
+ return sec->sh.sh_flags & SHF_EXECINSTR;
+}
+
static inline bool sec_changed(struct section *sec)
{
return sec->_changed;
@@ -222,6 +283,11 @@ static inline bool is_32bit_reloc(struct reloc *reloc)
return reloc->sec->sh.sh_entsize < 16;
}
+static inline unsigned long sec_size(struct section *sec)
+{
+ return sec->sh.sh_size;
+}
+
#define __get_reloc_field(reloc, field) \
({ \
is_32bit_reloc(reloc) ? \
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index c0beefb93b62..fc2cf8dba1c0 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -142,12 +142,12 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
if (!sec)
continue;
- if (sec->sh.sh_size % entry->size != 0) {
+ if (sec_size(sec) % entry->size != 0) {
ERROR("%s size not a multiple of %d", sec->name, entry->size);
return -1;
}
- nr_entries = sec->sh.sh_size / entry->size;
+ nr_entries = sec_size(sec) / entry->size;
for (idx = 0; idx < nr_entries; idx++) {
alt = malloc(sizeof(*alt));
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 27/64] objtool: Mark .cold subfunctions
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (25 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 26/64] objtool: Add section/symbol type helpers Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 28/64] objtool: Fix weak symbol hole detection for .cold functions Josh Poimboeuf
` (36 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Introduce a flag to identify .cold subfunctions so they can be detected
easier and faster.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 14 ++++++--------
tools/objtool/elf.c | 19 ++++++++++---------
tools/objtool/include/objtool/elf.h | 1 +
3 files changed, 17 insertions(+), 17 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b5b324bcc9fa..f76de990183d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1574,7 +1574,9 @@ static int add_jump_destinations(struct objtool_file *file)
/*
* Cross-function jump.
*/
- if (func && insn_func(jump_dest) && func != insn_func(jump_dest)) {
+
+ if (func && insn_func(jump_dest) && !func->cold &&
+ insn_func(jump_dest)->cold) {
/*
* For GCC 8+, create parent/child links for any cold
@@ -1591,11 +1593,8 @@ static int add_jump_destinations(struct objtool_file *file)
* case where the parent function's only reference to a
* subfunction is through a jump table.
*/
- if (!strstr(func->name, ".cold") &&
- strstr(insn_func(jump_dest)->name, ".cold")) {
- func->cfunc = insn_func(jump_dest);
- insn_func(jump_dest)->pfunc = func;
- }
+ func->cfunc = insn_func(jump_dest);
+ insn_func(jump_dest)->pfunc = func;
}
if (jump_is_sibling_call(file, insn, jump_dest)) {
@@ -4029,9 +4028,8 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
* If this hole jumps to a .cold function, mark it ignore too.
*/
if (insn->jump_dest && insn_func(insn->jump_dest) &&
- strstr(insn_func(insn->jump_dest)->name, ".cold")) {
+ insn_func(insn->jump_dest)->cold)
insn_func(insn->jump_dest)->ignore = true;
- }
}
return false;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d36c0d42fd7b..59568381486c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -441,6 +441,10 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
list_add(&sym->list, entry);
elf_hash_add(symbol, &sym->hash, sym->idx);
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
+
+ if (is_func_sym(sym) && strstr(sym->name, ".cold"))
+ sym->cold = 1;
+ sym->pfunc = sym->cfunc = sym;
}
static int read_symbols(struct elf *elf)
@@ -527,18 +531,15 @@ static int read_symbols(struct elf *elf)
sec_for_each_sym(sec, sym) {
char *pname;
size_t pnamelen;
- if (!is_func_sym(sym))
+
+ if (!sym->cold)
continue;
- if (sym->pfunc == NULL)
- sym->pfunc = sym;
-
- if (sym->cfunc == NULL)
- sym->cfunc = sym;
-
coldstr = strstr(sym->name, ".cold");
- if (!coldstr)
- continue;
+ if (!coldstr) {
+ ERROR("%s(): cold subfunction without \".cold\"?", sym->name);
+ return -1;
+ }
pnamelen = coldstr - sym->name;
pname = strndup(sym->name, pnamelen);
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 0914dadece0b..f41496b0ad8f 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -71,6 +71,7 @@ struct symbol {
u8 local_label : 1;
u8 frame_pointer : 1;
u8 ignore : 1;
+ u8 cold : 1;
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 28/64] objtool: Fix weak symbol hole detection for .cold functions
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (26 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 27/64] objtool: Mark .cold subfunctions Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 29/64] objtool: Mark prefix functions Josh Poimboeuf
` (35 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
When ignore_unreachable_insn() looks for weak function holes which jump
to their .cold functions, it assumes the parent function comes before
the corresponding .cold function in the symbol table. That's not
necessarily the case with -ffunction-sections.
Mark all the holes beforehand (including .cold functions) so the
ordering of the discovery doesn't matter.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 84 ++++++++++++++-------------
tools/objtool/include/objtool/check.h | 3 +-
2 files changed, 45 insertions(+), 42 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index f76de990183d..80bafcdb42af 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2504,6 +2504,44 @@ static void mark_rodata(struct objtool_file *file)
file->rodata = found;
}
+static void mark_holes(struct objtool_file *file)
+{
+ struct instruction *insn;
+ bool in_hole = false;
+
+ if (!opts.link)
+ return;
+
+ /*
+ * Whole archive runs might encounter dead code from weak symbols.
+ * This is where the linker will have dropped the weak symbol in
+ * favour of a regular symbol, but leaves the code in place.
+ */
+ for_each_insn(file, insn) {
+ if (insn->sym || !find_symbol_hole_containing(insn->sec, insn->offset)) {
+ in_hole = false;
+ continue;
+ }
+
+ /* Skip function padding and pfx code */
+ if (!in_hole && insn->type == INSN_NOP)
+ continue;
+
+ in_hole = true;
+ insn->hole = 1;
+
+ /*
+ * If this hole jumps to a .cold function, mark it ignore.
+ */
+ if (insn->jump_dest) {
+ struct symbol *dest_func = insn_func(insn->jump_dest);
+
+ if (dest_func && dest_func->cold)
+ dest_func->ignore = true;
+ }
+ }
+}
+
static int decode_sections(struct objtool_file *file)
{
mark_rodata(file);
@@ -2556,6 +2594,9 @@ static int decode_sections(struct objtool_file *file)
if (read_unwind_hints(file))
return -1;
+ /* Must be after add_jump_destinations() */
+ mark_holes(file);
+
/*
* Must be after add_call_destinations() such that it can override
* dead_end_function() marks.
@@ -3984,7 +4025,8 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
struct instruction *prev_insn;
int i;
- if (insn->type == INSN_NOP || insn->type == INSN_TRAP || (func && func->ignore))
+ if (insn->type == INSN_NOP || insn->type == INSN_TRAP ||
+ insn->hole || (func && func->ignore))
return true;
/*
@@ -3995,46 +4037,6 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
!strcmp(insn->sec->name, ".altinstr_aux"))
return true;
- /*
- * Whole archive runs might encounter dead code from weak symbols.
- * This is where the linker will have dropped the weak symbol in
- * favour of a regular symbol, but leaves the code in place.
- *
- * In this case we'll find a piece of code (whole function) that is not
- * covered by a !section symbol. Ignore them.
- */
- if (opts.link && !func) {
- int size = find_symbol_hole_containing(insn->sec, insn->offset);
- unsigned long end = insn->offset + size;
-
- if (!size) /* not a hole */
- return false;
-
- if (size < 0) /* hole until the end */
- return true;
-
- sec_for_each_insn_continue(file, insn) {
- /*
- * If we reach a visited instruction at or before the
- * end of the hole, ignore the unreachable.
- */
- if (insn->visited)
- return true;
-
- if (insn->offset >= end)
- break;
-
- /*
- * If this hole jumps to a .cold function, mark it ignore too.
- */
- if (insn->jump_dest && insn_func(insn->jump_dest) &&
- insn_func(insn->jump_dest)->cold)
- insn_func(insn->jump_dest)->ignore = true;
- }
-
- return false;
- }
-
if (!func)
return false;
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 00fb745e7233..0f4e7ac929ef 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -64,7 +64,8 @@ struct instruction {
noendbr : 1,
unret : 1,
visited : 4,
- no_reloc : 1;
+ no_reloc : 1,
+ hole : 1;
/* 10 bit hole */
struct alt_group *alt_group;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 29/64] objtool: Mark prefix functions
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (27 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 28/64] objtool: Fix weak symbol hole detection for .cold functions Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-27 10:31 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 30/64] objtool: Simplify reloc offset calculation in unwind_read_hints() Josh Poimboeuf
` (34 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, introduce a flag to
identify __pfx_*() and __cfi_*() functions in advance so they don't need
to be manually identified every time a check is needed.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 3 +--
tools/objtool/elf.c | 4 ++++
tools/objtool/include/objtool/elf.h | 6 ++++++
3 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 80bafcdb42af..55cc3a2a21c9 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3564,8 +3564,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
/* Ignore KCFI type preambles, which always fall through */
- if (!strncmp(func->name, "__cfi_", 6) ||
- !strncmp(func->name, "__pfx_", 6))
+ if (is_prefix_func(func))
return 0;
if (file->ignore_unreachables)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 59568381486c..1bb86151243a 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -442,6 +442,10 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
elf_hash_add(symbol, &sym->hash, sym->idx);
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
+ if (is_func_sym(sym) &&
+ (strstarts(sym->name, "__pfx_") || strstarts(sym->name, "__cfi_")))
+ sym->prefix = 1;
+
if (is_func_sym(sym) && strstr(sym->name, ".cold"))
sym->cold = 1;
sym->pfunc = sym->cfunc = sym;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index f41496b0ad8f..842faec1b9a9 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -72,6 +72,7 @@ struct symbol {
u8 frame_pointer : 1;
u8 ignore : 1;
u8 cold : 1;
+ u8 prefix : 1;
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;
@@ -229,6 +230,11 @@ static inline bool is_local_sym(struct symbol *sym)
return sym->bind == STB_LOCAL;
}
+static inline bool is_prefix_func(struct symbol *sym)
+{
+ return is_func_sym(sym) && sym->prefix;
+}
+
static inline bool is_reloc_sec(struct section *sec)
{
return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 30/64] objtool: Simplify reloc offset calculation in unwind_read_hints()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (28 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 29/64] objtool: Mark prefix functions Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 31/64] objtool: Avoid emptying lists for duplicate sections Josh Poimboeuf
` (33 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Simplify the relocation offset calculation in unwind_read_hints(),
similar to other conversions which have already been done.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 55cc3a2a21c9..9ffde9389c53 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2199,14 +2199,7 @@ static int read_unwind_hints(struct objtool_file *file)
return -1;
}
- if (is_sec_sym(reloc->sym)) {
- offset = reloc_addend(reloc);
- } else if (reloc->sym->local_label) {
- offset = reloc->sym->offset;
- } else {
- ERROR("unexpected relocation symbol type in %s", sec->rsec->name);
- return -1;
- }
+ offset = reloc->sym->offset + reloc_addend(reloc);
insn = find_insn(file, reloc->sym->sec, offset);
if (!insn) {
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 31/64] objtool: Avoid emptying lists for duplicate sections
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (29 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 30/64] objtool: Simplify reloc offset calculation in unwind_read_hints() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 32/64] objtool: Rename --Werror to --werror Josh Poimboeuf
` (32 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
When a to-be-created section already exists, there's no point in
emptying the various lists if their respective sections already exist.
In fact it's better to leave them intact as they might get used later.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 9ffde9389c53..87d2ba7739d5 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -634,7 +634,6 @@ static int create_static_call_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".static_call_sites");
if (sec) {
- INIT_LIST_HEAD(&file->static_call_list);
WARN("file already has .static_call_sites section, skipping");
return 0;
}
@@ -850,7 +849,6 @@ static int create_cfi_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".cfi_sites");
if (sec) {
- INIT_LIST_HEAD(&file->call_list);
WARN("file already has .cfi_sites section, skipping");
return 0;
}
@@ -899,7 +897,6 @@ static int create_mcount_loc_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, "__mcount_loc");
if (sec) {
- INIT_LIST_HEAD(&file->mcount_loc_list);
WARN("file already has __mcount_loc section, skipping");
return 0;
}
@@ -944,7 +941,6 @@ static int create_direct_call_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".call_sites");
if (sec) {
- INIT_LIST_HEAD(&file->call_list);
WARN("file already has .call_sites section, skipping");
return 0;
}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 32/64] objtool: Rename --Werror to --werror
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (30 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 31/64] objtool: Avoid emptying lists for duplicate sections Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 33/64] objtool: Resurrect --backup option Josh Poimboeuf
` (31 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The objtool --Werror option name is stylistically inconsistent: halfway
between GCC's single-dash capitalized -Werror and objtool's double-dash
--lowercase convention, making it unnecessarily hard to remember.
Make the 'W' lower case (--werror) for consistency with objtool's other
options.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
scripts/Makefile.lib | 2 +-
scripts/Makefile.vmlinux_o | 2 +-
tools/objtool/builtin-check.c | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index b95560266124..15fee73e9289 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -191,7 +191,7 @@ objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE) += --static-call
objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION) += --uaccess
objtool-args-$(or $(CONFIG_GCOV_KERNEL),$(CONFIG_KCOV)) += --no-unreachable
objtool-args-$(CONFIG_PREFIX_SYMBOLS) += --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)
-objtool-args-$(CONFIG_OBJTOOL_WERROR) += --Werror
+objtool-args-$(CONFIG_OBJTOOL_WERROR) += --werror
objtool-args = $(objtool-args-y) \
$(if $(delay-objtool), --link) \
diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
index b024ffb3e201..fed5200195df 100644
--- a/scripts/Makefile.vmlinux_o
+++ b/scripts/Makefile.vmlinux_o
@@ -41,7 +41,7 @@ objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
ifeq ($(delay-objtool),y)
vmlinux-objtool-args-y += $(objtool-args-y)
else
-vmlinux-objtool-args-$(CONFIG_OBJTOOL_WERROR) += --Werror
+vmlinux-objtool-args-$(CONFIG_OBJTOOL_WERROR) += --werror
endif
vmlinux-objtool-args-$(CONFIG_NOINSTR_VALIDATION) += --noinstr \
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 80239843e9f0..43139143edf8 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -100,7 +100,7 @@ static const struct option check_options[] = {
OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"),
OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
OPT_BOOLEAN('v', "verbose", &opts.verbose, "verbose warnings"),
- OPT_BOOLEAN(0, "Werror", &opts.werror, "return error on warnings"),
+ OPT_BOOLEAN(0, "werror", &opts.werror, "return error on warnings"),
OPT_END(),
};
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 33/64] objtool: Resurrect --backup option
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (31 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 32/64] objtool: Rename --Werror to --werror Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 34/64] objtool: Reindent check_options[] Josh Poimboeuf
` (30 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Peter Zijlstra
The --backup option was removed with the following commit:
aa8b3e64fd39 ("objtool: Create backup on error and print args")
... which tied the backup functionality to --verbose, and only for
warnings/errors.
It's a bit inelegant and out of scope to tie that to --verbose.
Bring back the old --backup option, but with the new behavior: only on
warnings/errors, and print the args to make it easier to recreate.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/builtin-check.c | 25 +++++++++++--------------
tools/objtool/check.c | 4 +++-
tools/objtool/include/objtool/builtin.h | 3 ++-
3 files changed, 16 insertions(+), 16 deletions(-)
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 43139143edf8..a8c349f2273d 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -91,6 +91,7 @@ static const struct option check_options[] = {
OPT_GROUP("Options:"),
OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),
+ OPT_BOOLEAN(0, "backup", &opts.backup, "create backup (.orig) file on warning/error"),
OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"),
OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),
@@ -244,12 +245,9 @@ static void save_argv(int argc, const char **argv)
};
}
-void print_args(void)
+int make_backup(void)
{
- char *backup = NULL;
-
- if (opts.output || opts.dryrun)
- goto print;
+ char *backup;
/*
* Make a backup before kbuild deletes the file so the error
@@ -258,33 +256,32 @@ void print_args(void)
backup = malloc(strlen(objname) + strlen(ORIG_SUFFIX) + 1);
if (!backup) {
ERROR_GLIBC("malloc");
- goto print;
+ return 1;
}
strcpy(backup, objname);
strcat(backup, ORIG_SUFFIX);
- if (copy_file(objname, backup)) {
- backup = NULL;
- goto print;
- }
+ if (copy_file(objname, backup))
+ return 1;
-print:
/*
- * Print the cmdline args to make it easier to recreate. If '--output'
- * wasn't used, add it to the printed args with the backup as input.
+ * Print the cmdline args to make it easier to recreate.
*/
+
fprintf(stderr, "%s", orig_argv[0]);
for (int i = 1; i < orig_argc; i++) {
char *arg = orig_argv[i];
- if (backup && !strcmp(arg, objname))
+ /* Modify the printed args to use the backup */
+ if (!opts.output && !strcmp(arg, objname))
fprintf(stderr, " %s -o %s", backup, objname);
else
fprintf(stderr, " %s", arg);
}
fprintf(stderr, "\n");
+ return 0;
}
int objtool_run(int argc, const char **argv)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 87d2ba7739d5..46ace2c80317 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4745,9 +4745,11 @@ int check(struct objtool_file *file)
if (opts.verbose) {
if (opts.werror && warnings)
WARN("%d warning(s) upgraded to errors", warnings);
- print_args();
disas_warned_funcs(file);
}
+ if (opts.backup && make_backup())
+ return 1;
+
return ret;
}
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 6b08666fa69d..de6c08f8e060 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -29,6 +29,7 @@ struct opts {
/* options: */
bool backtrace;
+ bool backup;
bool dryrun;
bool link;
bool mnop;
@@ -47,6 +48,6 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[]);
int objtool_run(int argc, const char **argv);
-void print_args(void);
+int make_backup(void);
#endif /* _BUILTIN_H */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 34/64] objtool: Reindent check_options[]
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (32 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 33/64] objtool: Resurrect --backup option Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 35/64] objtool: Refactor add_jump_destinations() Josh Poimboeuf
` (29 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Bring the cmdline check_options[] array back into vertical alignment for
better readability.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/builtin-check.c | 52 +++++++++++++++++------------------
1 file changed, 26 insertions(+), 26 deletions(-)
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index a8c349f2273d..86b1a05c9353 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -73,35 +73,35 @@ static int parse_hacks(const struct option *opt, const char *str, int unset)
static const struct option check_options[] = {
OPT_GROUP("Actions:"),
+ OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
- OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
- OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
- OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),
- OPT_BOOLEAN(0, "orc", &opts.orc, "generate ORC metadata"),
- OPT_BOOLEAN('r', "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
- OPT_BOOLEAN(0, "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
- OPT_BOOLEAN(0, "unret", &opts.unret, "validate entry unret placement"),
- OPT_INTEGER(0, "prefix", &opts.prefix, "generate prefix symbols"),
- OPT_BOOLEAN('l', "sls", &opts.sls, "validate straight-line-speculation mitigations"),
- OPT_BOOLEAN('s', "stackval", &opts.stackval, "validate frame pointer rules"),
- OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"),
- OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
- OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
- OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
+ OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
+ OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
+ OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),
+ OPT_BOOLEAN(0, "orc", &opts.orc, "generate ORC metadata"),
+ OPT_BOOLEAN('r', "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
+ OPT_BOOLEAN(0, "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
+ OPT_BOOLEAN(0, "unret", &opts.unret, "validate entry unret placement"),
+ OPT_INTEGER(0, "prefix", &opts.prefix, "generate prefix symbols"),
+ OPT_BOOLEAN('l', "sls", &opts.sls, "validate straight-line-speculation mitigations"),
+ OPT_BOOLEAN('s', "stackval", &opts.stackval, "validate frame pointer rules"),
+ OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"),
+ OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
+ OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
OPT_GROUP("Options:"),
- OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),
- OPT_BOOLEAN(0, "backup", &opts.backup, "create backup (.orig) file on warning/error"),
- OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
- OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"),
- OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),
- OPT_BOOLEAN(0, "mnop", &opts.mnop, "nop out mcount call sites"),
- OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
- OPT_STRING('o', "output", &opts.output, "file", "output file name"),
- OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"),
- OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
- OPT_BOOLEAN('v', "verbose", &opts.verbose, "verbose warnings"),
- OPT_BOOLEAN(0, "werror", &opts.werror, "return error on warnings"),
+ OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),
+ OPT_BOOLEAN(0, "backup", &opts.backup, "create backup (.orig) file on warning/error"),
+ OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
+ OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"),
+ OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),
+ OPT_BOOLEAN(0, "mnop", &opts.mnop, "nop out mcount call sites"),
+ OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
+ OPT_STRING('o', "output", &opts.output, "file", "output file name"),
+ OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"),
+ OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
+ OPT_BOOLEAN('v', "verbose", &opts.verbose, "verbose warnings"),
+ OPT_BOOLEAN(0, "werror", &opts.werror, "return error on warnings"),
OPT_END(),
};
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 35/64] objtool: Refactor add_jump_destinations()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (33 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 34/64] objtool: Reindent check_options[] Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 36/64] objtool: Simplify special symbol handling in elf_update_symbol() Josh Poimboeuf
` (28 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The add_jump_destinations() logic is a bit weird and convoluted after
being incrementally tweaked over the years. Refactor it to hopefully be
more logical and straightforward.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 222 +++++++++++++---------------
tools/objtool/include/objtool/elf.h | 4 +-
2 files changed, 106 insertions(+), 120 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 46ace2c80317..3afc748ba516 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1422,9 +1422,14 @@ static void add_return_call(struct objtool_file *file, struct instruction *insn,
}
static bool is_first_func_insn(struct objtool_file *file,
- struct instruction *insn, struct symbol *sym)
+ struct instruction *insn)
{
- if (insn->offset == sym->offset)
+ struct symbol *func = insn_func(insn);
+
+ if (!func)
+ return false;
+
+ if (insn->offset == func->offset)
return true;
/* Allow direct CALL/JMP past ENDBR */
@@ -1432,51 +1437,30 @@ static bool is_first_func_insn(struct objtool_file *file,
struct instruction *prev = prev_insn_same_sym(file, insn);
if (prev && prev->type == INSN_ENDBR &&
- insn->offset == sym->offset + prev->len)
+ insn->offset == func->offset + prev->len)
return true;
}
return false;
}
-/*
- * A sibling call is a tail-call to another symbol -- to differentiate from a
- * recursive tail-call which is to the same symbol.
- */
-static bool jump_is_sibling_call(struct objtool_file *file,
- struct instruction *from, struct instruction *to)
-{
- struct symbol *fs = from->sym;
- struct symbol *ts = to->sym;
-
- /* Not a sibling call if from/to a symbol hole */
- if (!fs || !ts)
- return false;
-
- /* Not a sibling call if not targeting the start of a symbol. */
- if (!is_first_func_insn(file, to, ts))
- return false;
-
- /* Disallow sibling calls into STT_NOTYPE */
- if (is_notype_sym(ts))
- return false;
-
- /* Must not be self to be a sibling */
- return fs->pfunc != ts->pfunc;
-}
-
/*
* Find the destination instructions for all jumps.
*/
static int add_jump_destinations(struct objtool_file *file)
{
- struct instruction *insn, *jump_dest;
+ struct instruction *insn;
struct reloc *reloc;
- struct section *dest_sec;
- unsigned long dest_off;
for_each_insn(file, insn) {
struct symbol *func = insn_func(insn);
+ struct instruction *dest_insn;
+ struct section *dest_sec;
+ struct symbol *dest_sym;
+ unsigned long dest_off;
+
+ if (!is_static_jump(insn))
+ continue;
if (insn->jump_dest) {
/*
@@ -1485,51 +1469,53 @@ static int add_jump_destinations(struct objtool_file *file)
*/
continue;
}
- if (!is_static_jump(insn))
- continue;
reloc = insn_reloc(file, insn);
if (!reloc) {
dest_sec = insn->sec;
dest_off = arch_jump_destination(insn);
- } else if (is_sec_sym(reloc->sym)) {
- dest_sec = reloc->sym->sec;
- dest_off = arch_insn_adjusted_addend(insn, reloc);
- } else if (reloc->sym->retpoline_thunk) {
- if (add_retpoline_call(file, insn))
- return -1;
- continue;
- } else if (reloc->sym->return_thunk) {
- add_return_call(file, insn, true);
- continue;
- } else if (func) {
- /*
- * External sibling call or internal sibling call with
- * STT_FUNC reloc.
- */
- if (add_call_dest(file, insn, reloc->sym, true))
- return -1;
- continue;
- } else if (reloc->sym->sec->idx) {
- dest_sec = reloc->sym->sec;
- dest_off = reloc->sym->sym.st_value +
- arch_insn_adjusted_addend(insn, reloc);
+ dest_sym = dest_sec->sym;
} else {
- /* non-func asm code jumping to another file */
- continue;
+ dest_sym = reloc->sym;
+ if (is_undef_sym(dest_sym)) {
+ if (dest_sym->retpoline_thunk) {
+ if (add_retpoline_call(file, insn))
+ return -1;
+ continue;
+ }
+
+ if (dest_sym->return_thunk) {
+ add_return_call(file, insn, true);
+ continue;
+ }
+
+ /* External symbol */
+ if (func) {
+ /* External sibling call */
+ if (add_call_dest(file, insn, dest_sym, true))
+ return -1;
+ continue;
+ }
+
+ /* Non-func asm code jumping to external symbol */
+ continue;
+ }
+
+ dest_sec = dest_sym->sec;
+ dest_off = dest_sym->offset + arch_insn_adjusted_addend(insn, reloc);
}
- jump_dest = find_insn(file, dest_sec, dest_off);
- if (!jump_dest) {
+ dest_insn = find_insn(file, dest_sec, dest_off);
+ if (!dest_insn) {
struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
/*
- * This is a special case for retbleed_untrain_ret().
- * It jumps to __x86_return_thunk(), but objtool
- * can't find the thunk's starting RET
- * instruction, because the RET is also in the
- * middle of another instruction. Objtool only
- * knows about the outer instruction.
+ * retbleed_untrain_ret() jumps to
+ * __x86_return_thunk(), but objtool can't find
+ * the thunk's starting RET instruction,
+ * because the RET is also in the middle of
+ * another instruction. Objtool only knows
+ * about the outer instruction.
*/
if (sym && sym->embedded_insn) {
add_return_call(file, insn, false);
@@ -1537,73 +1523,73 @@ static int add_jump_destinations(struct objtool_file *file)
}
/*
- * GCOV/KCOV dead code can jump to the end of the
- * function/section.
+ * GCOV/KCOV dead code can jump to the end of
+ * the function/section.
*/
if (file->ignore_unreachables && func &&
dest_sec == insn->sec &&
dest_off == func->offset + func->len)
continue;
- ERROR_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
- dest_sec->name, dest_off);
+ ERROR_INSN(insn, "can't find jump dest instruction at %s",
+ offstr(dest_sec, dest_off));
return -1;
}
- /*
- * An intra-TU jump in retpoline.o might not have a relocation
- * for its jump dest, in which case the above
- * add_{retpoline,return}_call() didn't happen.
- */
- if (jump_dest->sym && jump_dest->offset == jump_dest->sym->offset) {
- if (jump_dest->sym->retpoline_thunk) {
- if (add_retpoline_call(file, insn))
- return -1;
- continue;
- }
- if (jump_dest->sym->return_thunk) {
- add_return_call(file, insn, true);
- continue;
- }
+ if (!dest_sym || is_sec_sym(dest_sym)) {
+ dest_sym = dest_insn->sym;
+ if (!dest_sym)
+ goto set_jump_dest;
}
- /*
- * Cross-function jump.
- */
-
- if (func && insn_func(jump_dest) && !func->cold &&
- insn_func(jump_dest)->cold) {
-
- /*
- * For GCC 8+, create parent/child links for any cold
- * subfunctions. This is _mostly_ redundant with a
- * similar initialization in read_symbols().
- *
- * If a function has aliases, we want the *first* such
- * function in the symbol table to be the subfunction's
- * parent. In that case we overwrite the
- * initialization done in read_symbols().
- *
- * However this code can't completely replace the
- * read_symbols() code because this doesn't detect the
- * case where the parent function's only reference to a
- * subfunction is through a jump table.
- */
- func->cfunc = insn_func(jump_dest);
- insn_func(jump_dest)->pfunc = func;
- }
-
- if (jump_is_sibling_call(file, insn, jump_dest)) {
- /*
- * Internal sibling call without reloc or with
- * STT_SECTION reloc.
- */
- if (add_call_dest(file, insn, insn_func(jump_dest), true))
+ if (dest_sym->retpoline_thunk && dest_insn->offset == dest_sym->offset) {
+ if (add_retpoline_call(file, insn))
return -1;
continue;
}
- insn->jump_dest = jump_dest;
+ if (dest_sym->return_thunk && dest_insn->offset == dest_sym->offset) {
+ add_return_call(file, insn, true);
+ continue;
+ }
+
+ if (!insn->sym || insn->sym == dest_insn->sym)
+ goto set_jump_dest;
+
+ /*
+ * Internal cross-function jump.
+ */
+
+ /*
+ * For GCC 8+, create parent/child links for any cold
+ * subfunctions. This is _mostly_ redundant with a
+ * similar initialization in read_symbols().
+ *
+ * If a function has aliases, we want the *first* such
+ * function in the symbol table to be the subfunction's
+ * parent. In that case we overwrite the
+ * initialization done in read_symbols().
+ *
+ * However this code can't completely replace the
+ * read_symbols() code because this doesn't detect the
+ * case where the parent function's only reference to a
+ * subfunction is through a jump table.
+ */
+ if (func && dest_sym->cold) {
+ func->cfunc = dest_sym;
+ dest_sym->pfunc = func;
+ goto set_jump_dest;
+ }
+
+ if (is_first_func_insn(file, dest_insn)) {
+ /* Internal sibling call */
+ if (add_call_dest(file, insn, dest_sym, true))
+ return -1;
+ continue;
+ }
+
+set_jump_dest:
+ insn->jump_dest = dest_insn;
}
return 0;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 842faec1b9a9..74c7b84b5310 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -180,9 +180,9 @@ static inline unsigned int elf_text_rela_type(struct elf *elf)
return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
}
-static inline bool sym_has_sec(struct symbol *sym)
+static inline bool is_undef_sym(struct symbol *sym)
{
- return sym->sec->idx;
+ return !sym->sec->idx;
}
static inline bool is_null_sym(struct symbol *sym)
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 36/64] objtool: Simplify special symbol handling in elf_update_symbol()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (34 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 35/64] objtool: Refactor add_jump_destinations() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 37/64] objtool: Generalize elf_create_symbol() Josh Poimboeuf
` (27 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
!sym->sec isn't actually a thing: even STT_UNDEF and other special
symbol types belong to NULL section 0.
Simplify the initialization of 'shndx' accordingly.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 1bb86151243a..4e274197bcd6 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -634,7 +634,7 @@ static int elf_update_sym_relocs(struct elf *elf, struct symbol *sym)
static int elf_update_symbol(struct elf *elf, struct section *symtab,
struct section *symtab_shndx, struct symbol *sym)
{
- Elf32_Word shndx = sym->sec ? sym->sec->idx : SHN_UNDEF;
+ Elf32_Word shndx;
Elf_Data *symtab_data = NULL, *shndx_data = NULL;
Elf64_Xword entsize = symtab->sh.sh_entsize;
int max_idx, idx = sym->idx;
@@ -642,8 +642,7 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
bool is_special_shndx = sym->sym.st_shndx >= SHN_LORESERVE &&
sym->sym.st_shndx != SHN_XINDEX;
- if (is_special_shndx)
- shndx = sym->sym.st_shndx;
+ shndx = is_special_shndx ? sym->sym.st_shndx : sym->sec->idx;
s = elf_getscn(elf->elf, symtab->idx);
if (!s) {
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 37/64] objtool: Generalize elf_create_symbol()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (35 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 36/64] objtool: Simplify special symbol handling in elf_update_symbol() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 38/64] objtool: Generalize elf_create_section() Josh Poimboeuf
` (26 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, broaden the
elf_create_symbol() interface to give callers more control and reduce
duplication of some subtle setup logic.
While at it, make elf_create_symbol() and elf_create_section_symbol()
public so sections can be created by the upcoming klp diff code.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 111 +++++++++++++++-------------
tools/objtool/include/objtool/elf.h | 11 ++-
2 files changed, 69 insertions(+), 53 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4e274197bcd6..127e39b05a86 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -760,24 +760,60 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
return 0;
}
-static struct symbol *
-__elf_create_symbol(struct elf *elf, struct symbol *sym)
+static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
+
+struct symbol *elf_create_symbol(struct elf *elf, const char *name,
+ struct section *sec, unsigned int bind,
+ unsigned int type, unsigned long offset,
+ size_t size)
{
struct section *symtab, *symtab_shndx;
Elf32_Word first_non_local, new_idx;
- struct symbol *old;
+ struct symbol *old, *sym;
+
+ sym = calloc(1, sizeof(*sym));
+ if (!sym) {
+ ERROR_GLIBC("calloc");
+ return NULL;
+ }
+
+ sym->name = strdup(name);
+ if (!sym->name) {
+ ERROR_GLIBC("strdup");
+ return NULL;
+ }
+
+ if (type != STT_SECTION) {
+ sym->sym.st_name = elf_add_string(elf, NULL, sym->name);
+ if (sym->sym.st_name == -1)
+ return NULL;
+ }
+
+ if (sec) {
+ sym->sec = sec;
+ } else {
+ sym->sec = find_section_by_index(elf, 0);
+ if (!sym->sec) {
+ ERROR("no NULL section");
+ return NULL;
+ }
+ }
+
+ sym->sym.st_info = GELF_ST_INFO(bind, type);
+ sym->sym.st_value = offset;
+ sym->sym.st_size = size;
symtab = find_section_by_name(elf, ".symtab");
- if (symtab) {
- symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
- } else {
+ if (!symtab) {
ERROR("no .symtab");
return NULL;
}
+ symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
+
new_idx = sec_num_entries(symtab);
- if (GELF_ST_BIND(sym->sym.st_info) != STB_LOCAL)
+ if (bind != STB_LOCAL)
goto non_local;
/*
@@ -815,10 +851,8 @@ __elf_create_symbol(struct elf *elf, struct symbol *sym)
non_local:
sym->idx = new_idx;
- if (elf_update_symbol(elf, symtab, symtab_shndx, sym)) {
- ERROR("elf_update_symbol");
+ if (sym->idx && elf_update_symbol(elf, symtab, symtab_shndx, sym))
return NULL;
- }
symtab->sh.sh_size += symtab->sh.sh_entsize;
mark_sec_changed(elf, symtab, true);
@@ -828,64 +862,39 @@ __elf_create_symbol(struct elf *elf, struct symbol *sym)
mark_sec_changed(elf, symtab_shndx, true);
}
+ elf_add_symbol(elf, sym);
+
return sym;
}
-static struct symbol *
-elf_create_section_symbol(struct elf *elf, struct section *sec)
+struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec)
{
struct symbol *sym = calloc(1, sizeof(*sym));
- if (!sym) {
- ERROR_GLIBC("malloc");
+ sym = elf_create_symbol(elf, sec->name, sec, STB_LOCAL, STT_SECTION, 0, 0);
+ if (!sym)
return NULL;
- }
- sym->name = sec->name;
- sym->sec = sec;
-
- // st_name 0
- sym->sym.st_info = GELF_ST_INFO(STB_LOCAL, STT_SECTION);
- // st_other 0
- // st_value 0
- // st_size 0
-
- sym = __elf_create_symbol(elf, sym);
- if (sym)
- elf_add_symbol(elf, sym);
+ sec->sym = sym;
return sym;
}
-static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
-
struct symbol *
-elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size)
+elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, size_t size)
{
- struct symbol *sym = calloc(1, sizeof(*sym));
size_t namelen = strlen(orig->name) + sizeof("__pfx_");
- char *name = malloc(namelen);
-
- if (!sym || !name) {
- ERROR_GLIBC("malloc");
- return NULL;
- }
+ char name[SYM_NAME_LEN];
+ unsigned long offset;
snprintf(name, namelen, "__pfx_%s", orig->name);
- sym->name = name;
- sym->sec = orig->sec;
+ offset = orig->sym.st_value - size;
- sym->sym.st_name = elf_add_string(elf, NULL, name);
- sym->sym.st_info = orig->sym.st_info;
- sym->sym.st_value = orig->sym.st_value - size;
- sym->sym.st_size = size;
-
- sym = __elf_create_symbol(elf, sym);
- if (sym)
- elf_add_symbol(elf, sym);
-
- return sym;
+ return elf_create_symbol(elf, name, orig->sec,
+ GELF_ST_BIND(orig->sym.st_info),
+ GELF_ST_TYPE(orig->sym.st_info),
+ offset, size);
}
static struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
@@ -931,7 +940,7 @@ struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
unsigned long insn_off)
{
struct symbol *sym = insn_sec->sym;
- int addend = insn_off;
+ s64 addend = insn_off;
if (!is_text_sec(insn_sec)) {
ERROR("bad call to %s() for data symbol %s", __func__, sym->name);
@@ -948,8 +957,6 @@ struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
sym = elf_create_section_symbol(elf, insn_sec);
if (!sym)
return NULL;
-
- insn_sec->sym = sym;
}
return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 74c7b84b5310..ffdf9ec3882e 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -15,6 +15,8 @@
#include <linux/jhash.h>
#include <arch/elf.h>
+#define SYM_NAME_LEN 512
+
#ifdef LIBELF_USE_DEPRECATED
# define elf_getshdrnum elf_getshnum
# define elf_getshdrstrndx elf_getshstrndx
@@ -119,7 +121,14 @@ struct section *elf_create_section_pair(struct elf *elf, const char *name,
size_t entsize, unsigned int nr,
unsigned int reloc_nr);
-struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size);
+struct symbol *elf_create_symbol(struct elf *elf, const char *name,
+ struct section *sec, unsigned int bind,
+ unsigned int type, unsigned long offset,
+ size_t size);
+struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec);
+struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig,
+ size_t size);
+
struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
unsigned long offset,
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 38/64] objtool: Generalize elf_create_section()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (36 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 37/64] objtool: Generalize elf_create_symbol() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 39/64] objtool: Add elf_create_data() Josh Poimboeuf
` (25 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, broaden the
elf_create_section() interface to give callers more control and reduce
duplication of some subtle setup logic.
While at it, make elf_create_rela_section() public so sections can be
created by the upcoming klp diff code.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 118 ++++++++++++++++------------
tools/objtool/include/objtool/elf.h | 7 +-
tools/objtool/orc_gen.c | 6 +-
3 files changed, 77 insertions(+), 54 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 127e39b05a86..4f56ea426683 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -1135,51 +1135,53 @@ static int elf_add_string(struct elf *elf, struct section *strtab, const char *s
}
struct section *elf_create_section(struct elf *elf, const char *name,
- size_t entsize, unsigned int nr)
+ size_t size, size_t entsize,
+ unsigned int type, unsigned int align,
+ unsigned int flags)
{
struct section *sec, *shstrtab;
- size_t size = entsize * nr;
Elf_Scn *s;
- sec = malloc(sizeof(*sec));
- if (!sec) {
- ERROR_GLIBC("malloc");
+ if (name && find_section_by_name(elf, name)) {
+ ERROR("section '%s' already exists", name);
+ return NULL;
+ }
+
+ sec = calloc(1, sizeof(*sec));
+ if (!sec) {
+ ERROR_GLIBC("calloc");
return NULL;
}
- memset(sec, 0, sizeof(*sec));
INIT_LIST_HEAD(&sec->symbol_list);
+ /* don't actually create the section, just the data structures */
+ if (type == SHT_NULL)
+ goto add;
+
s = elf_newscn(elf->elf);
if (!s) {
ERROR_ELF("elf_newscn");
return NULL;
}
- sec->name = strdup(name);
- if (!sec->name) {
- ERROR_GLIBC("strdup");
- return NULL;
- }
-
sec->idx = elf_ndxscn(s);
- sec->data = elf_newdata(s);
- if (!sec->data) {
- ERROR_ELF("elf_newdata");
- return NULL;
- }
-
- sec->data->d_size = size;
- sec->data->d_align = 1;
-
if (size) {
- sec->data->d_buf = malloc(size);
- if (!sec->data->d_buf) {
- ERROR_GLIBC("malloc");
+ sec->data = elf_newdata(s);
+ if (!sec->data) {
+ ERROR_ELF("elf_newdata");
+ return NULL;
+ }
+
+ sec->data->d_size = size;
+ sec->data->d_align = 1;
+
+ sec->data->d_buf = calloc(1, size);
+ if (!sec->data->d_buf) {
+ ERROR_GLIBC("calloc");
return NULL;
}
- memset(sec->data->d_buf, 0, size);
}
if (!gelf_getshdr(s, &sec->sh)) {
@@ -1189,34 +1191,44 @@ struct section *elf_create_section(struct elf *elf, const char *name,
sec->sh.sh_size = size;
sec->sh.sh_entsize = entsize;
- sec->sh.sh_type = SHT_PROGBITS;
- sec->sh.sh_addralign = 1;
- sec->sh.sh_flags = SHF_ALLOC;
+ sec->sh.sh_type = type;
+ sec->sh.sh_addralign = align;
+ sec->sh.sh_flags = flags;
- /* Add section name to .shstrtab (or .strtab for Clang) */
- shstrtab = find_section_by_name(elf, ".shstrtab");
- if (!shstrtab)
- shstrtab = find_section_by_name(elf, ".strtab");
- if (!shstrtab) {
- ERROR("can't find .shstrtab or .strtab section");
- return NULL;
+ if (name) {
+ sec->name = strdup(name);
+ if (!sec->name) {
+ ERROR("strdup");
+ return NULL;
+ }
+
+ /* Add section name to .shstrtab (or .strtab for Clang) */
+ shstrtab = find_section_by_name(elf, ".shstrtab");
+ if (!shstrtab) {
+ shstrtab = find_section_by_name(elf, ".strtab");
+ if (!shstrtab) {
+ ERROR("can't find .shstrtab or .strtab");
+ return NULL;
+ }
+ }
+ sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
+ if (sec->sh.sh_name == -1)
+ return NULL;
+
+ elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
}
- sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
- if (sec->sh.sh_name == -1)
- return NULL;
+add:
list_add_tail(&sec->list, &elf->sections);
elf_hash_add(section, &sec->hash, sec->idx);
- elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
mark_sec_changed(elf, sec, true);
return sec;
}
-static struct section *elf_create_rela_section(struct elf *elf,
- struct section *sec,
- unsigned int reloc_nr)
+struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
+ unsigned int reloc_nr)
{
struct section *rsec;
char *rsec_name;
@@ -1229,22 +1241,23 @@ static struct section *elf_create_rela_section(struct elf *elf,
strcpy(rsec_name, ".rela");
strcat(rsec_name, sec->name);
- rsec = elf_create_section(elf, rsec_name, elf_rela_size(elf), reloc_nr);
+ rsec = elf_create_section(elf, rsec_name, reloc_nr * elf_rela_size(elf),
+ elf_rela_size(elf), SHT_RELA, elf_addr_size(elf),
+ SHF_INFO_LINK);
free(rsec_name);
if (!rsec)
return NULL;
- rsec->data->d_type = ELF_T_RELA;
- rsec->sh.sh_type = SHT_RELA;
- rsec->sh.sh_addralign = elf_addr_size(elf);
rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
rsec->sh.sh_info = sec->idx;
- rsec->sh.sh_flags = SHF_INFO_LINK;
- rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));
- if (!rsec->relocs) {
- ERROR_GLIBC("calloc");
- return NULL;
+ if (reloc_nr) {
+ rsec->data->d_type = ELF_T_RELA;
+ rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));
+ if (!rsec->relocs) {
+ ERROR_GLIBC("calloc");
+ return NULL;
+ }
}
sec->rsec = rsec;
@@ -1259,7 +1272,8 @@ struct section *elf_create_section_pair(struct elf *elf, const char *name,
{
struct section *sec;
- sec = elf_create_section(elf, name, entsize, nr);
+ sec = elf_create_section(elf, name, nr * entsize, entsize,
+ SHT_PROGBITS, 1, SHF_ALLOC);
if (!sec)
return NULL;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index ffdf9ec3882e..b366516b119d 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -116,11 +116,16 @@ struct elf {
struct elf *elf_open_read(const char *name, int flags);
struct section *elf_create_section(struct elf *elf, const char *name,
- size_t entsize, unsigned int nr);
+ size_t size, size_t entsize,
+ unsigned int type, unsigned int align,
+ unsigned int flags);
struct section *elf_create_section_pair(struct elf *elf, const char *name,
size_t entsize, unsigned int nr,
unsigned int reloc_nr);
+struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
+ unsigned int reloc_nr);
+
struct symbol *elf_create_symbol(struct elf *elf, const char *name,
struct section *sec, unsigned int bind,
unsigned int type, unsigned long offset,
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 6eff3d6a125c..9d380abc2ed3 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -127,7 +127,11 @@ int orc_create(struct objtool_file *file)
return -1;
}
orc_sec = elf_create_section(file->elf, ".orc_unwind",
- sizeof(struct orc_entry), nr);
+ nr * sizeof(struct orc_entry),
+ sizeof(struct orc_entry),
+ SHT_PROGBITS,
+ 1,
+ SHF_ALLOC);
if (!orc_sec)
return -1;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 39/64] objtool: Add elf_create_data()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (37 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 38/64] objtool: Generalize elf_create_section() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 40/64] objtool: Add elf_create_reloc() and elf_init_reloc() Josh Poimboeuf
` (24 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, refactor
elf_add_string() by adding a new elf_add_data() helper which allows the
adding of arbitrary data to a section.
Make both interfaces public so they can be used by the upcoming klp diff
code.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 66 ++++++++++++++++++++---------
tools/objtool/include/objtool/elf.h | 10 +++--
2 files changed, 54 insertions(+), 22 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4f56ea426683..535bdcf077d0 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -18,10 +18,11 @@
#include <errno.h>
#include <linux/interval_tree_generic.h>
#include <objtool/builtin.h>
-
#include <objtool/elf.h>
#include <objtool/warn.h>
+#define ALIGN_UP(x, align_to) (((x) + ((align_to)-1)) & ~((align_to)-1))
+
static inline u32 str_hash(const char *str)
{
return jhash(str, strlen(str), 0);
@@ -760,8 +761,6 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
return 0;
}
-static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
-
struct symbol *elf_create_symbol(struct elf *elf, const char *name,
struct section *sec, unsigned int bind,
unsigned int type, unsigned long offset,
@@ -1097,11 +1096,9 @@ struct elf *elf_open_read(const char *name, int flags)
return NULL;
}
-static int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
+unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
{
- Elf_Data *data;
- Elf_Scn *s;
- int len;
+ unsigned int offset;
if (!strtab)
strtab = find_section_by_name(elf, ".strtab");
@@ -1110,28 +1107,59 @@ static int elf_add_string(struct elf *elf, struct section *strtab, const char *s
return -1;
}
- s = elf_getscn(elf->elf, strtab->idx);
+ if (!strtab->sh.sh_addralign) {
+ ERROR("'%s': invalid sh_addralign", strtab->name);
+ return -1;
+ }
+
+ offset = ALIGN_UP(strtab->sh.sh_size, strtab->sh.sh_addralign);
+
+ if (!elf_add_data(elf, strtab, str, strlen(str) + 1))
+ return -1;
+
+ return offset;
+}
+
+void *elf_add_data(struct elf *elf, struct section *sec, const void *data, size_t size)
+{
+ unsigned long offset;
+ Elf_Scn *s;
+
+ if (!sec->sh.sh_addralign) {
+ ERROR("'%s': invalid sh_addralign", sec->name);
+ return NULL;
+ }
+
+ s = elf_getscn(elf->elf, sec->idx);
if (!s) {
ERROR_ELF("elf_getscn");
- return -1;
+ return NULL;
}
- data = elf_newdata(s);
- if (!data) {
+ sec->data = elf_newdata(s);
+ if (!sec->data) {
ERROR_ELF("elf_newdata");
- return -1;
+ return NULL;
}
- data->d_buf = strdup(str);
- data->d_size = strlen(str) + 1;
- data->d_align = 1;
+ sec->data->d_buf = calloc(1, size);
+ if (!sec->data->d_buf) {
+ ERROR_GLIBC("calloc");
+ return NULL;
+ }
- len = strtab->sh.sh_size;
- strtab->sh.sh_size += data->d_size;
+ if (data)
+ memcpy(sec->data->d_buf, data, size);
- mark_sec_changed(elf, strtab, true);
+ sec->data->d_size = size;
+ sec->data->d_align = 1;
- return len;
+ offset = ALIGN_UP(sec->sh.sh_size, sec->sh.sh_addralign);
+ sec->sh.sh_size = offset + size;
+
+ mark_sec_changed(elf, sec, true);
+
+ return sec->data->d_buf;
}
struct section *elf_create_section(struct elf *elf, const char *name,
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index b366516b119d..fc00f86bedba 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -134,6 +134,10 @@ struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec);
struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig,
size_t size);
+void *elf_add_data(struct elf *elf, struct section *sec, const void *data,
+ size_t size);
+
+unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
unsigned long offset,
@@ -147,9 +151,9 @@ struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
struct symbol *sym,
s64 addend);
-int elf_write_insn(struct elf *elf, struct section *sec,
- unsigned long offset, unsigned int len,
- const char *insn);
+int elf_write_insn(struct elf *elf, struct section *sec, unsigned long offset,
+ unsigned int len, const char *insn);
+
int elf_write(struct elf *elf);
void elf_close(struct elf *elf);
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 40/64] objtool: Add elf_create_reloc() and elf_init_reloc()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (38 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 39/64] objtool: Add elf_create_data() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 41/64] objtool: Add elf_create_file() Josh Poimboeuf
` (23 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
elf_create_rela_section() is quite limited in that it requires the
caller to know how many relocations need to be allocated up front.
In preparation for the objtool klp diff subcommand, allow an arbitrary
number of relocations to be created and initialized on demand after
section creation.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/elf.c | 151 +++++++++++++++++++++++++---
tools/objtool/include/objtool/elf.h | 9 ++
2 files changed, 145 insertions(+), 15 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 535bdcf077d0..0e98cf2ab533 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -22,6 +22,8 @@
#include <objtool/warn.h>
#define ALIGN_UP(x, align_to) (((x) + ((align_to)-1)) & ~((align_to)-1))
+#define ALIGN_UP_POW2(x) (1U << ((8 * sizeof(x)) - __builtin_clz((x) - 1U)))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
static inline u32 str_hash(const char *str)
{
@@ -896,10 +898,9 @@ elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, size_t size)
offset, size);
}
-static struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
- unsigned int reloc_idx,
- unsigned long offset, struct symbol *sym,
- s64 addend, unsigned int type)
+struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
+ unsigned int reloc_idx, unsigned long offset,
+ struct symbol *sym, s64 addend, unsigned int type)
{
struct reloc *reloc, empty = { 0 };
@@ -1001,12 +1002,14 @@ static int read_relocs(struct elf *elf)
rsec->base->rsec = rsec;
- nr_reloc = 0;
- rsec->relocs = calloc(sec_num_entries(rsec), sizeof(*reloc));
+ rsec->nr_alloc_relocs = sec_num_entries(rsec);
+ rsec->relocs = calloc(rsec->nr_alloc_relocs, sizeof(*reloc));
if (!rsec->relocs) {
ERROR_GLIBC("calloc");
return -1;
}
+
+ nr_reloc = 0;
for (i = 0; i < sec_num_entries(rsec); i++) {
reloc = &rsec->relocs[i];
@@ -1255,8 +1258,99 @@ struct section *elf_create_section(struct elf *elf, const char *name,
return sec;
}
+static int elf_alloc_reloc(struct elf *elf, struct section *rsec)
+{
+ struct reloc *old_relocs, *old_relocs_end, *new_relocs;
+ unsigned int nr_relocs_old = sec_num_entries(rsec);
+ unsigned int nr_relocs_new = nr_relocs_old + 1;
+ unsigned long nr_alloc;
+ struct symbol *sym;
+
+ if (!rsec->data) {
+ rsec->data = elf_newdata(elf_getscn(elf->elf, rsec->idx));
+ if (!rsec->data) {
+ ERROR_ELF("elf_newdata");
+ return -1;
+ }
+
+ rsec->data->d_align = 1;
+ rsec->data->d_type = ELF_T_RELA;
+ rsec->data->d_buf = NULL;
+ }
+
+ rsec->data->d_size = nr_relocs_new * elf_rela_size(elf);
+ rsec->sh.sh_size = rsec->data->d_size;
+
+ nr_alloc = MAX(64, ALIGN_UP_POW2(nr_relocs_new));
+ if (nr_alloc <= rsec->nr_alloc_relocs)
+ return 0;
+ rsec->nr_alloc_relocs = nr_alloc;
+
+ rsec->data->d_buf = realloc(rsec->data->d_buf,
+ nr_alloc * elf_rela_size(elf));
+ if (!rsec->data->d_buf) {
+ ERROR_GLIBC("realloc");
+ return -1;
+ }
+
+ old_relocs = rsec->relocs;
+ new_relocs = calloc(nr_alloc, sizeof(struct reloc));
+ if (!new_relocs) {
+ ERROR_GLIBC("calloc");
+ return -1;
+ }
+
+ if (!old_relocs)
+ goto done;
+
+ /*
+ * The struct reloc's address has changed. Update all the symbols and
+ * relocs which reference it.
+ */
+
+ old_relocs_end = &old_relocs[nr_relocs_old];
+ for_each_sym(elf, sym) {
+ struct reloc *reloc;
+
+ reloc = sym->relocs;
+ if (!reloc)
+ continue;
+
+ if (reloc >= old_relocs && reloc < old_relocs_end)
+ sym->relocs = &new_relocs[reloc - old_relocs];
+
+ while (1) {
+ struct reloc *next_reloc = sym_next_reloc(reloc);
+
+ if (!next_reloc)
+ break;
+
+ if (next_reloc >= old_relocs && next_reloc < old_relocs_end)
+ set_sym_next_reloc(reloc, &new_relocs[next_reloc - old_relocs]);
+
+ reloc = next_reloc;
+ }
+ }
+
+ memcpy(new_relocs, old_relocs, nr_relocs_old * sizeof(struct reloc));
+
+ for (int i = 0; i < nr_relocs_old; i++) {
+ struct reloc *old = &old_relocs[i];
+ struct reloc *new = &new_relocs[i];
+ u32 key = reloc_hash(old);
+
+ elf_hash_del(reloc, &old->hash, key);
+ elf_hash_add(reloc, &new->hash, key);
+ }
+
+ free(old_relocs);
+done:
+ rsec->relocs = new_relocs;
+ return 0;
+}
+
struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
- unsigned int reloc_nr)
+ unsigned int nr_relocs)
{
struct section *rsec;
char *rsec_name;
@@ -1269,34 +1363,61 @@ struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
strcpy(rsec_name, ".rela");
strcat(rsec_name, sec->name);
- rsec = elf_create_section(elf, rsec_name, reloc_nr * elf_rela_size(elf),
+ rsec = elf_create_section(elf, rsec_name, nr_relocs * elf_rela_size(elf),
elf_rela_size(elf), SHT_RELA, elf_addr_size(elf),
SHF_INFO_LINK);
free(rsec_name);
if (!rsec)
return NULL;
- rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
- rsec->sh.sh_info = sec->idx;
-
- if (reloc_nr) {
+ if (nr_relocs) {
rsec->data->d_type = ELF_T_RELA;
- rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));
+
+ rsec->nr_alloc_relocs = nr_relocs;
+ rsec->relocs = calloc(nr_relocs, sizeof(struct reloc));
if (!rsec->relocs) {
ERROR_GLIBC("calloc");
return NULL;
}
}
+ rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
+ rsec->sh.sh_info = sec->idx;
+
sec->rsec = rsec;
rsec->base = sec;
return rsec;
}
+struct reloc *elf_create_reloc(struct elf *elf, struct section *sec,
+ unsigned long offset,
+ struct symbol *sym, s64 addend,
+ unsigned int type)
+{
+ struct section *rsec = sec->rsec;
+
+ if (!rsec) {
+ rsec = elf_create_rela_section(elf, sec, 0);
+ if (!rsec)
+ return NULL;
+ }
+
+ if (find_reloc_by_dest(elf, sec, offset)) {
+ ERROR_FUNC(sec, offset, "duplicate reloc");
+ return NULL;
+ }
+
+ if (elf_alloc_reloc(elf, rsec))
+ return NULL;
+
+ return elf_init_reloc(elf, rsec, sec_num_entries(rsec) - 1, offset, sym,
+ addend, type);
+}
+
struct section *elf_create_section_pair(struct elf *elf, const char *name,
size_t entsize, unsigned int nr,
- unsigned int reloc_nr)
+ unsigned int nr_relocs)
{
struct section *sec;
@@ -1305,7 +1426,7 @@ struct section *elf_create_section_pair(struct elf *elf, const char *name,
if (!sec)
return NULL;
- if (!elf_create_rela_section(elf, sec, reloc_nr))
+ if (!elf_create_rela_section(elf, sec, nr_relocs))
return NULL;
return sec;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index fc00f86bedba..5c663e475890 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -47,6 +47,7 @@ struct section {
int idx;
bool _changed, text, rodata, noinstr, init, truncate;
struct reloc *relocs;
+ unsigned long nr_alloc_relocs;
};
struct symbol {
@@ -139,6 +140,14 @@ void *elf_add_data(struct elf *elf, struct section *sec, const void *data,
unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
+struct reloc *elf_create_reloc(struct elf *elf, struct section *sec,
+ unsigned long offset, struct symbol *sym,
+ s64 addend, unsigned int type);
+
+struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
+ unsigned int reloc_idx, unsigned long offset,
+ struct symbol *sym, s64 addend, unsigned int type);
+
struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
unsigned long offset,
unsigned int reloc_idx,
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 41/64] objtool: Add elf_create_file()
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (39 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 40/64] objtool: Add elf_create_reloc() and elf_init_reloc() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 42/64] kbuild,x86: Fix special section module permissions Josh Poimboeuf
` (22 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add interface to enable the creation of a new ELF file.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/builtin-check.c | 2 +-
tools/objtool/elf.c | 144 +++++++++++++++++++++++++++-
tools/objtool/include/objtool/elf.h | 5 +-
3 files changed, 147 insertions(+), 4 deletions(-)
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 86b1a05c9353..3172f7e98147 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -327,5 +327,5 @@ int objtool_run(int argc, const char **argv)
if (!opts.dryrun && file->elf->changed && elf_write(file->elf))
return 1;
- return 0;
+ return elf_close(file->elf);
}
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 0e98cf2ab533..b88190fe7131 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -16,6 +16,7 @@
#include <string.h>
#include <unistd.h>
#include <errno.h>
+#include <libgen.h>
#include <linux/interval_tree_generic.h>
#include <objtool/builtin.h>
#include <objtool/elf.h>
@@ -1062,6 +1063,12 @@ struct elf *elf_open_read(const char *name, int flags)
goto err;
}
+ elf->name = strdup(name);
+ if (!elf->name) {
+ ERROR_GLIBC("strdup");
+ return NULL;
+ }
+
if ((flags & O_ACCMODE) == O_RDONLY)
cmd = ELF_C_READ_MMAP;
else if ((flags & O_ACCMODE) == O_RDWR)
@@ -1099,6 +1106,137 @@ struct elf *elf_open_read(const char *name, int flags)
return NULL;
}
+struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)
+{
+ struct section *null, *symtab, *strtab, *shstrtab;
+ char *dir, *base, *tmp_name;
+ struct symbol *sym;
+ struct elf *elf;
+
+ elf_version(EV_CURRENT);
+
+ elf = calloc(1, sizeof(*elf));
+ if (!elf) {
+ ERROR_GLIBC("calloc");
+ return NULL;
+ }
+
+ INIT_LIST_HEAD(&elf->sections);
+
+ dir = strdup(name);
+ if (!dir) {
+ ERROR_GLIBC("strdup");
+ return NULL;
+ }
+
+ dir = dirname(dir);
+
+ base = strdup(name);
+ if (!base) {
+ ERROR_GLIBC("strdup");
+ return NULL;
+ }
+
+ base = basename(base);
+
+ tmp_name = malloc(256);
+ if (!tmp_name) {
+ ERROR_GLIBC("malloc");
+ return NULL;
+ }
+
+ snprintf(tmp_name, 256, "%s/%s.XXXXXX", dir, base);
+
+ elf->fd = mkstemp(tmp_name);
+ if (elf->fd == -1) {
+ ERROR_GLIBC("can't create tmp file");
+ exit(1);
+ }
+
+ elf->tmp_name = tmp_name;
+
+ elf->name = strdup(name);
+ if (!elf->name) {
+ ERROR_GLIBC("strdup");
+ return NULL;
+ }
+
+ elf->elf = elf_begin(elf->fd, ELF_C_WRITE, NULL);
+ if (!elf->elf) {
+ ERROR_ELF("elf_begin");
+ return NULL;
+ }
+
+ if (!gelf_newehdr(elf->elf, ELFCLASS64)) {
+ ERROR_ELF("gelf_newehdr");
+ return NULL;
+ }
+
+ memcpy(&elf->ehdr, ehdr, sizeof(elf->ehdr));
+
+ if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {
+ ERROR_ELF("gelf_update_ehdr");
+ return NULL;
+ }
+
+ if (!elf_alloc_hash(section, 1000) ||
+ !elf_alloc_hash(section_name, 1000) ||
+ !elf_alloc_hash(symbol, 10000) ||
+ !elf_alloc_hash(symbol_name, 10000) ||
+ !elf_alloc_hash(reloc, 100000))
+ return NULL;
+
+ null = elf_create_section(elf, NULL, 0, 0, SHT_NULL, 0, 0);
+ shstrtab = elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);
+ strtab = elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);
+
+ if (!null || !shstrtab || !strtab)
+ return NULL;
+
+ null->name = "";
+ shstrtab->name = ".shstrtab";
+ strtab->name = ".strtab";
+
+ null->sh.sh_name = elf_add_string(elf, shstrtab, null->name);
+ shstrtab->sh.sh_name = elf_add_string(elf, shstrtab, shstrtab->name);
+ strtab->sh.sh_name = elf_add_string(elf, shstrtab, strtab->name);
+
+ if (null->sh.sh_name == -1 || shstrtab->sh.sh_name == -1 || strtab->sh.sh_name == -1)
+ return NULL;
+
+ elf_hash_add(section_name, &null->name_hash, str_hash(null->name));
+ elf_hash_add(section_name, &strtab->name_hash, str_hash(strtab->name));
+ elf_hash_add(section_name, &shstrtab->name_hash, str_hash(shstrtab->name));
+
+ if (elf_add_string(elf, strtab, "") == -1)
+ return NULL;
+
+ symtab = elf_create_section(elf, ".symtab", 0x18, 0x18, SHT_SYMTAB, 0x8, 0);
+ if (!symtab)
+ return NULL;
+
+ symtab->sh.sh_link = strtab->idx;
+ symtab->sh.sh_info = 1;
+
+ elf->ehdr.e_shstrndx = shstrtab->idx;
+ if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {
+ ERROR_ELF("gelf_update_ehdr");
+ return NULL;
+ }
+
+ sym = calloc(1, sizeof(*sym));
+ if (!sym) {
+ ERROR_GLIBC("calloc");
+ return NULL;
+ }
+
+ sym->name = "";
+ sym->sec = null;
+ elf_add_symbol(elf, sym);
+
+ return elf;
+}
+
unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
{
unsigned int offset;
@@ -1544,7 +1682,7 @@ int elf_write(struct elf *elf)
return 0;
}
-void elf_close(struct elf *elf)
+int elf_close(struct elf *elf)
{
if (elf->elf)
elf_end(elf->elf);
@@ -1552,8 +1690,12 @@ void elf_close(struct elf *elf)
if (elf->fd > 0)
close(elf->fd);
+ if (elf->tmp_name && rename(elf->tmp_name, elf->name))
+ return -1;
+
/*
* NOTE: All remaining allocations are leaked on purpose. Objtool is
* about to exit anyway.
*/
+ return 0;
}
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 5c663e475890..a0fc252e1993 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -93,7 +93,7 @@ struct elf {
GElf_Ehdr ehdr;
int fd;
bool changed;
- const char *name;
+ const char *name, *tmp_name;
unsigned int num_files;
struct list_head sections;
unsigned long num_relocs;
@@ -115,6 +115,7 @@ struct elf {
};
struct elf *elf_open_read(const char *name, int flags);
+struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name);
struct section *elf_create_section(struct elf *elf, const char *name,
size_t size, size_t entsize,
@@ -164,7 +165,7 @@ int elf_write_insn(struct elf *elf, struct section *sec, unsigned long offset,
unsigned int len, const char *insn);
int elf_write(struct elf *elf);
-void elf_close(struct elf *elf);
+int elf_close(struct elf *elf);
struct section *find_section_by_name(const struct elf *elf, const char *name);
struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 42/64] kbuild,x86: Fix special section module permissions
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (40 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 41/64] objtool: Add elf_create_file() Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-27 10:53 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 43/64] x86/alternative: Define ELF section entry size for alternatives Josh Poimboeuf
` (21 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Masahiro Yamada
An upcoming patch will add the SHF_MERGE flag to x86 __jump_table and
__bug_table so their entry sizes can be defined in inline asm.
However, those sections have SHF_WRITE, which the Clang linker (lld)
explicitly forbids combining with SHF_MERGE.
Those sections are modified at runtime and must remain writable. While
SHF_WRITE is ignored by vmlinux, it's still needed for modules.
To work around the linker interference, remove SHF_WRITE during
compilation and restore it after linking the module.
Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/Kconfig | 3 +++
arch/x86/Kconfig | 1 +
arch/x86/include/asm/bug.h | 4 ++--
arch/x86/include/asm/jump_label.h | 2 +-
scripts/Makefile.modfinal | 19 ++++++++++++++-----
5 files changed, 21 insertions(+), 8 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index a3308a220f86..350ea5df5e8d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1314,6 +1314,9 @@ config HAVE_NOINSTR_HACK
config HAVE_NOINSTR_VALIDATION
bool
+config NEED_MODULE_PERMISSIONS_FIX
+ bool
+
config HAVE_UACCESS_VALIDATION
bool
select OBJTOOL
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 71019b3b54ea..62faa62b5959 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -310,6 +310,7 @@ config X86
select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
select IRQ_FORCED_THREADING
select LOCK_MM_AND_FIND_VMA
+ select NEED_MODULE_PERMISSIONS_FIX
select NEED_PER_CPU_EMBED_FIRST_CHUNK
select NEED_PER_CPU_PAGE_FIRST_CHUNK
select NEED_SG_DMA_LENGTH
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 8593976b32cb..59e155ee3c76 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -42,7 +42,7 @@
#define _BUG_FLAGS(cond_str, ins, flags, extra) \
do { \
asm_inline volatile("1:\t" ins "\n" \
- ".pushsection __bug_table,\"aw\"\n" \
+ ".pushsection __bug_table,\"a\"\n" \
"2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
"\t" __BUG_REL(%c0) "\t# bug_entry::file\n" \
"\t.word %c1" "\t# bug_entry::line\n" \
@@ -60,7 +60,7 @@ do { \
#define _BUG_FLAGS(cond_str, ins, flags, extra) \
do { \
asm_inline volatile("1:\t" ins "\n" \
- ".pushsection __bug_table,\"aw\"\n" \
+ ".pushsection __bug_table,\"a\"\n" \
"2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
"\t.word %c0" "\t# bug_entry::flags\n" \
"\t.org 2b+%c1\n" \
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 61dd1dee7812..cd21554b3675 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -13,7 +13,7 @@
#include <linux/types.h>
#define JUMP_TABLE_ENTRY(key, label) \
- ".pushsection __jump_table, \"aw\" \n\t" \
+ ".pushsection __jump_table, \"a\"\n\t" \
_ASM_ALIGN "\n\t" \
".long 1b - . \n\t" \
".long " label " - . \n\t" \
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 542ba462ed3e..7a888e1ff70f 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -28,12 +28,24 @@ ccflags-remove-y := $(CC_FLAGS_CFI)
.module-common.o: $(srctree)/scripts/module-common.c FORCE
$(call if_changed_rule,cc_o_c)
+ifdef CONFIG_NEED_MODULE_PERMISSIONS_FIX
+cmd_fix_mod_permissions = \
+ $(OBJCOPY) --set-section-flags __jump_table=alloc,data \
+ --set-section-flags __bug_table=alloc,data $@ \
+ --set-section-flags .static_call_sites=alloc,data $@
+endif
+
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o = \
$(LD) -r $(KBUILD_LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-T $(objtree)/scripts/module.lds -o $@ $(filter %.o, $^)
+define rule_ld_ko_o
+ $(call cmd_and_savecmd,ld_ko_o)
+ $(call cmd,fix_mod_permissions)
+endef
+
quiet_cmd_btf_ko = BTF [M] $@
cmd_btf_ko = \
if [ ! -f $(objtree)/vmlinux ]; then \
@@ -46,14 +58,11 @@ quiet_cmd_btf_ko = BTF [M] $@
# Same as newer-prereqs, but allows to exclude specified extra dependencies
newer_prereqs_except = $(filter-out $(PHONY) $(1),$?)
-# Same as if_changed, but allows to exclude specified extra dependencies
-if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
- $(cmd); \
- printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
+if_changed_rule_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check),$(rule_$(1)),@:)
# Re-generate module BTFs if either module's .ko or vmlinux changed
%.ko: %.o %.mod.o .module-common.o $(objtree)/scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),$(objtree)/vmlinux) FORCE
- +$(call if_changed_except,ld_ko_o,$(objtree)/vmlinux)
+ +$(call if_changed_rule_except,ld_ko_o,$(objtree)/vmlinux)
ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+$(if $(newer-prereqs),$(call cmd,btf_ko))
endif
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 43/64] x86/alternative: Define ELF section entry size for alternatives
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (41 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 42/64] kbuild,x86: Fix special section module permissions Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels Josh Poimboeuf
` (20 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, define the entry
size for the .altinstructions section in its ELF header. This will
allow tooling to extract individual entries.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/um/include/shared/common-offsets.h | 2 ++
arch/x86/include/asm/alternative.h | 5 +++--
arch/x86/include/asm/asm.h | 4 ++++
arch/x86/kernel/asm-offsets.c | 2 ++
arch/x86/um/shared/sysdep/kernel-offsets.h | 1 +
kernel/bounds.c | 1 +
scripts/mod/devicetable-offsets.c | 1 +
7 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/um/include/shared/common-offsets.h b/arch/um/include/shared/common-offsets.h
index 8ca66a1918c3..4e19103afd71 100644
--- a/arch/um/include/shared/common-offsets.h
+++ b/arch/um/include/shared/common-offsets.h
@@ -18,3 +18,5 @@ DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES);
DEFINE(UM_SECCOMP_ARCH_NATIVE, SECCOMP_ARCH_NATIVE);
+
+DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 15bc07a5ebb3..eb24d9ba30d7 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -197,7 +197,8 @@ static inline int alternatives_text_reserved(void *start, void *end)
"773:\n"
#define ALTINSTR_ENTRY(ft_flags) \
- ".pushsection .altinstructions,\"a\"\n" \
+ ".pushsection .altinstructions, \"aM\", @progbits, " \
+ __stringify(ALT_INSTR_SIZE) "\n" \
" .long 771b - .\n" /* label */ \
" .long 774f - .\n" /* new instruction */ \
" .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \
@@ -360,7 +361,7 @@ void nop_func(void);
741: \
.skip -(((744f-743f)-(741b-740b)) > 0) * ((744f-743f)-(741b-740b)),0x90 ;\
742: \
- .pushsection .altinstructions,"a" ; \
+ .pushsection .altinstructions, "aM", @progbits, ALT_INSTR_SIZE ;\
altinstr_entry 740b,743f,flag,742b-740b,744f-743f ; \
.popsection ; \
.pushsection .altinstr_replacement,"ax" ; \
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index f963848024a5..1f26f90a57ce 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -136,6 +136,10 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
#ifdef __KERNEL__
+#ifndef COMPILE_OFFSETS
+#include <asm/asm-offsets.h>
+#endif
+
# include <asm/extable_fixup_types.h>
/* Exception table entry */
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 6259b474073b..b51625c3f64c 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -123,4 +123,6 @@ static void __used common(void)
OFFSET(ARIA_CTX_rounds, aria_ctx, rounds);
#endif
+ BLANK();
+ DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
}
diff --git a/arch/x86/um/shared/sysdep/kernel-offsets.h b/arch/x86/um/shared/sysdep/kernel-offsets.h
index 6fd1ed400399..9f6d3d1a248c 100644
--- a/arch/x86/um/shared/sysdep/kernel-offsets.h
+++ b/arch/x86/um/shared/sysdep/kernel-offsets.h
@@ -1,4 +1,5 @@
/* SPDX-License-Identifier: GPL-2.0 */
+#define COMPILE_OFFSETS
#include <linux/stddef.h>
#include <linux/sched.h>
#include <linux/elf.h>
diff --git a/kernel/bounds.c b/kernel/bounds.c
index 29b2cd00df2c..02b619eb6106 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -6,6 +6,7 @@
*/
#define __GENERATING_BOUNDS_H
+#define COMPILE_OFFSETS
/* Include headers that define the enum constants of interest */
#include <linux/page-flags.h>
#include <linux/mmzone.h>
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index d3d00e85edf7..ef2ffb68f69d 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
+#define COMPILE_OFFSETS
#include <linux/kbuild.h>
#include <linux/mod_devicetable.h>
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (42 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 43/64] x86/alternative: Define ELF section entry size for alternatives Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-27 10:48 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 45/64] x86/static_call: Define ELF section entry size of static calls Josh Poimboeuf
` (19 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, define the entry
size for the __jump_table section in its ELF header. This will allow
tooling to extract individual entries.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/include/asm/jump_label.h | 17 +++++++++++------
kernel/bounds.c | 4 ++++
2 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index cd21554b3675..7a6b0e5d85c1 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -12,12 +12,17 @@
#include <linux/stringify.h>
#include <linux/types.h>
-#define JUMP_TABLE_ENTRY(key, label) \
- ".pushsection __jump_table, \"a\"\n\t" \
- _ASM_ALIGN "\n\t" \
- ".long 1b - . \n\t" \
- ".long " label " - . \n\t" \
- _ASM_PTR " " key " - . \n\t" \
+#ifndef COMPILE_OFFSETS
+#include <generated/bounds.h>
+#endif
+
+#define JUMP_TABLE_ENTRY(key, label) \
+ ".pushsection __jump_table, \"aM\", @progbits, " \
+ __stringify(JUMP_ENTRY_SIZE) "\n\t" \
+ _ASM_ALIGN "\n\t" \
+ ".long 1b - . \n\t" \
+ ".long " label " - . \n\t" \
+ _ASM_PTR " " key " - . \n\t" \
".popsection \n\t"
/* This macro is also expanded on the Rust side. */
diff --git a/kernel/bounds.c b/kernel/bounds.c
index 02b619eb6106..e4c7ded3dc48 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -13,6 +13,7 @@
#include <linux/kbuild.h>
#include <linux/log2.h>
#include <linux/spinlock_types.h>
+#include <linux/jump_label.h>
int main(void)
{
@@ -29,6 +30,9 @@ int main(void)
#else
DEFINE(LRU_GEN_WIDTH, 0);
DEFINE(__LRU_REFS_WIDTH, 0);
+#endif
+#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && defined(CONFIG_JUMP_LABEL)
+ DEFINE(JUMP_ENTRY_SIZE, sizeof(struct jump_entry));
#endif
/* End of constants */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 45/64] x86/static_call: Define ELF section entry size of static calls
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (43 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-27 10:51 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 46/64] x86/extable: Define ELF section entry size for exception table Josh Poimboeuf
` (18 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, define the entry
size for the .static_call_sites section in its ELF header. This will
allow tooling to extract individual entries.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/include/asm/static_call.h | 3 ++-
include/linux/static_call.h | 6 ------
include/linux/static_call_types.h | 6 ++++++
kernel/bounds.c | 4 ++++
tools/include/linux/static_call_types.h | 6 ++++++
tools/objtool/check.c | 11 +++++++++--
6 files changed, 27 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/static_call.h b/arch/x86/include/asm/static_call.h
index 41502bd2afd6..e03ad9bbbf59 100644
--- a/arch/x86/include/asm/static_call.h
+++ b/arch/x86/include/asm/static_call.h
@@ -58,7 +58,8 @@
ARCH_DEFINE_STATIC_CALL_TRAMP(name, __static_call_return0)
#define ARCH_ADD_TRAMP_KEY(name) \
- asm(".pushsection .static_call_tramp_key, \"a\" \n" \
+ asm(".pushsection .static_call_tramp_key, \"aM\", @progbits, " \
+ __stringify(STATIC_CALL_TRAMP_KEY_SIZE) "\n" \
".long " STATIC_CALL_TRAMP_STR(name) " - . \n" \
".long " STATIC_CALL_KEY_STR(name) " - . \n" \
".popsection \n")
diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index 78a77a4ae0ea..5210612817f2 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -172,12 +172,6 @@ struct static_call_mod {
struct static_call_site *sites;
};
-/* For finding the key associated with a trampoline */
-struct static_call_tramp_key {
- s32 tramp;
- s32 key;
-};
-
extern void __static_call_update(struct static_call_key *key, void *tramp, void *func);
extern int static_call_mod_init(struct module *mod);
extern int static_call_text_reserved(void *start, void *end);
diff --git a/include/linux/static_call_types.h b/include/linux/static_call_types.h
index 5a00b8b2cf9f..eb772df625d4 100644
--- a/include/linux/static_call_types.h
+++ b/include/linux/static_call_types.h
@@ -34,6 +34,12 @@ struct static_call_site {
s32 key;
};
+/* For finding the key associated with a trampoline */
+struct static_call_tramp_key {
+ s32 tramp;
+ s32 key;
+};
+
#define DECLARE_STATIC_CALL(name, func) \
extern struct static_call_key STATIC_CALL_KEY(name); \
extern typeof(func) STATIC_CALL_TRAMP(name);
diff --git a/kernel/bounds.c b/kernel/bounds.c
index e4c7ded3dc48..21c37e3ea629 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -14,6 +14,7 @@
#include <linux/log2.h>
#include <linux/spinlock_types.h>
#include <linux/jump_label.h>
+#include <linux/static_call_types.h>
int main(void)
{
@@ -33,6 +34,9 @@ int main(void)
#endif
#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && defined(CONFIG_JUMP_LABEL)
DEFINE(JUMP_ENTRY_SIZE, sizeof(struct jump_entry));
+#endif
+#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
+ DEFINE(STATIC_CALL_TRAMP_KEY_SIZE, sizeof(struct static_call_tramp_key));
#endif
/* End of constants */
diff --git a/tools/include/linux/static_call_types.h b/tools/include/linux/static_call_types.h
index 5a00b8b2cf9f..eb772df625d4 100644
--- a/tools/include/linux/static_call_types.h
+++ b/tools/include/linux/static_call_types.h
@@ -34,6 +34,12 @@ struct static_call_site {
s32 key;
};
+/* For finding the key associated with a trampoline */
+struct static_call_tramp_key {
+ s32 tramp;
+ s32 key;
+};
+
#define DECLARE_STATIC_CALL(name, func) \
extern struct static_call_key STATIC_CALL_KEY(name); \
extern typeof(func) STATIC_CALL_TRAMP(name);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3afc748ba516..c3e1ca3dba06 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -650,8 +650,15 @@ static int create_static_call_sections(struct objtool_file *file)
if (!sec)
return -1;
- /* Allow modules to modify the low bits of static_call_site::key */
- sec->sh.sh_flags |= SHF_WRITE;
+ /*
+ * Set SHF_MERGE to prevent tooling from stripping entsize.
+ *
+ * SHF_WRITE would also get set here to allow modules to modify the low
+ * bits of static_call_site::key, but the LLVM linker doesn't allow
+ * SHF_MERGE+SHF_WRITE for whatever reason. That gets fixed up by the
+ * makefiles with CONFIG_NEED_MODULE_PERMISSIONS_FIX.
+ */
+ sec->sh.sh_flags |= SHF_MERGE;
idx = 0;
list_for_each_entry(insn, &file->static_call_list, call_node) {
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 46/64] x86/extable: Define ELF section entry size for exception table
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (44 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 45/64] x86/static_call: Define ELF section entry size of static calls Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-27 10:52 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 47/64] x86/bug: Define ELF section entry size for bug table Josh Poimboeuf
` (17 subsequent siblings)
63 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, define the entry
size for the __ex_table section in its ELF header. This will allow
tooling to extract individual entries.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/um/include/asm/Kbuild | 1 -
arch/um/include/shared/common-offsets.h | 1 +
arch/x86/include/asm/asm.h | 18 ++++++++++--------
arch/x86/kernel/asm-offsets.c | 1 +
arch/x86/um/shared/sysdep/kernel-offsets.h | 1 +
5 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index 04ab3b653a48..1934fa0df888 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -5,7 +5,6 @@ generic-y += device.h
generic-y += dma-mapping.h
generic-y += emergency-restart.h
generic-y += exec.h
-generic-y += extable.h
generic-y += ftrace.h
generic-y += hw_irq.h
generic-y += irq_regs.h
diff --git a/arch/um/include/shared/common-offsets.h b/arch/um/include/shared/common-offsets.h
index 4e19103afd71..a6f77cb6aa7e 100644
--- a/arch/um/include/shared/common-offsets.h
+++ b/arch/um/include/shared/common-offsets.h
@@ -20,3 +20,4 @@ DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES);
DEFINE(UM_SECCOMP_ARCH_NATIVE, SECCOMP_ARCH_NATIVE);
DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
+DEFINE(EXTABLE_SIZE, sizeof(struct exception_table_entry));
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 1f26f90a57ce..e9b6d2d006c6 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -145,12 +145,12 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
/* Exception table entry */
#ifdef __ASSEMBLER__
-# define _ASM_EXTABLE_TYPE(from, to, type) \
- .pushsection "__ex_table","a" ; \
- .balign 4 ; \
- .long (from) - . ; \
- .long (to) - . ; \
- .long type ; \
+# define _ASM_EXTABLE_TYPE(from, to, type) \
+ .pushsection "__ex_table", "aM", @progbits, EXTABLE_SIZE; \
+ .balign 4 ; \
+ .long (from) - . ; \
+ .long (to) - . ; \
+ .long type ; \
.popsection
# ifdef CONFIG_KPROBES
@@ -193,7 +193,8 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
".purgem extable_type_reg\n"
# define _ASM_EXTABLE_TYPE(from, to, type) \
- " .pushsection \"__ex_table\",\"a\"\n" \
+ " .pushsection __ex_table, \"aM\", @progbits, " \
+ __stringify(EXTABLE_SIZE) "\n" \
" .balign 4\n" \
" .long (" #from ") - .\n" \
" .long (" #to ") - .\n" \
@@ -201,7 +202,8 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
" .popsection\n"
# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg) \
- " .pushsection \"__ex_table\",\"a\"\n" \
+ " .pushsection __ex_table, \"aM\", @progbits, " \
+ __stringify(EXTABLE_SIZE) "\n" \
" .balign 4\n" \
" .long (" #from ") - .\n" \
" .long (" #to ") - .\n" \
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index b51625c3f64c..3d3eef7fae32 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -125,4 +125,5 @@ static void __used common(void)
BLANK();
DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
+ DEFINE(EXTABLE_SIZE, sizeof(struct exception_table_entry));
}
diff --git a/arch/x86/um/shared/sysdep/kernel-offsets.h b/arch/x86/um/shared/sysdep/kernel-offsets.h
index 9f6d3d1a248c..8215a0200ddd 100644
--- a/arch/x86/um/shared/sysdep/kernel-offsets.h
+++ b/arch/x86/um/shared/sysdep/kernel-offsets.h
@@ -8,6 +8,7 @@
#include <linux/audit.h>
#include <asm/mman.h>
#include <asm/seccomp.h>
+#include <asm/extable.h>
/* workaround for a warning with -Wmissing-prototypes */
void foo(void);
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 47/64] x86/bug: Define ELF section entry size for bug table
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (45 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 46/64] x86/extable: Define ELF section entry size for exception table Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 48/64] x86/orc: Define ELF section entry size for unwind hints Josh Poimboeuf
` (16 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, define the entry
size for the __bug_table section in its ELF header. This will allow
tooling to extract individual entries.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/include/asm/bug.h | 45 ++++++++++++++++++++------------------
1 file changed, 24 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 59e155ee3c76..3aa28c687696 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -41,33 +41,36 @@
#define _BUG_FLAGS(cond_str, ins, flags, extra) \
do { \
- asm_inline volatile("1:\t" ins "\n" \
- ".pushsection __bug_table,\"a\"\n" \
- "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
- "\t" __BUG_REL(%c0) "\t# bug_entry::file\n" \
- "\t.word %c1" "\t# bug_entry::line\n" \
- "\t.word %c2" "\t# bug_entry::flags\n" \
- "\t.org 2b+%c3\n" \
- ".popsection\n" \
- extra \
- : : "i" (WARN_CONDITION_STR(cond_str) __FILE__), "i" (__LINE__), \
- "i" (flags), \
- "i" (sizeof(struct bug_entry))); \
+ asm_inline volatile( \
+ "1:\t" ins "\n" \
+ ".pushsection __bug_table, \"aM\", @progbits, %c3\n" \
+ "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
+ "\t" __BUG_REL(%c0) "\t# bug_entry::file\n" \
+ "\t.word %c1" "\t# bug_entry::line\n" \
+ "\t.word %c2" "\t# bug_entry::flags\n" \
+ "\t.org 2b+%c3\n" \
+ ".popsection\n" \
+ extra \
+ : : "i" (WARN_CONDITION_STR(cond_str) __FILE__), \
+ "i" (__LINE__), \
+ "i" (flags), \
+ "i" (sizeof(struct bug_entry))); \
} while (0)
#else /* !CONFIG_DEBUG_BUGVERBOSE */
#define _BUG_FLAGS(cond_str, ins, flags, extra) \
do { \
- asm_inline volatile("1:\t" ins "\n" \
- ".pushsection __bug_table,\"a\"\n" \
- "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
- "\t.word %c0" "\t# bug_entry::flags\n" \
- "\t.org 2b+%c1\n" \
- ".popsection\n" \
- extra \
- : : "i" (flags), \
- "i" (sizeof(struct bug_entry))); \
+ asm_inline volatile( \
+ "1:\t" ins "\n" \
+ ".pushsection __bug_table, \"aM\", @progbits, %c1\n" \
+ "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
+ "\t.word %c0" "\t# bug_entry::flags\n" \
+ "\t.org 2b+%c1\n" \
+ ".popsection\n" \
+ extra \
+ : : "i" (flags), \
+ "i" (sizeof(struct bug_entry))); \
} while (0)
#endif /* CONFIG_DEBUG_BUGVERBOSE */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 48/64] x86/orc: Define ELF section entry size for unwind hints
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (46 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 47/64] x86/bug: Define ELF section entry size for bug table Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 49/64] objtool: Unify STACK_FRAME_NON_STANDARD entry sizes Josh Poimboeuf
` (15 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, define the entry
size for the discard.unwind_hints section in its ELF header. This will
allow tooling to extract individual entries.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/linux/objtool.h | 11 ++++++++---
kernel/bounds.c | 4 ++++
2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 366ad004d794..c7a3851ae4ae 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -2,6 +2,10 @@
#ifndef _LINUX_OBJTOOL_H
#define _LINUX_OBJTOOL_H
+#ifndef COMPILE_OFFSETS
+#include <generated/bounds.h>
+#endif
+
#include <linux/objtool_types.h>
#ifdef CONFIG_OBJTOOL
@@ -10,9 +14,10 @@
#ifndef __ASSEMBLY__
-#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
+#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
"987: \n\t" \
- ".pushsection .discard.unwind_hints\n\t" \
+ ".pushsection .discard.unwind_hints, \"M\", @progbits, "\
+ __stringify(UNWIND_HINT_SIZE) "\n\t" \
/* struct unwind_hint */ \
".long 987b - .\n\t" \
".short " __stringify(sp_offset) "\n\t" \
@@ -88,7 +93,7 @@
*/
.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
.Lhere_\@:
- .pushsection .discard.unwind_hints
+ .pushsection .discard.unwind_hints, "M", @progbits, UNWIND_HINT_SIZE
/* struct unwind_hint */
.long .Lhere_\@ - .
.short \sp_offset
diff --git a/kernel/bounds.c b/kernel/bounds.c
index 21c37e3ea629..f9bc13727721 100644
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -15,6 +15,7 @@
#include <linux/spinlock_types.h>
#include <linux/jump_label.h>
#include <linux/static_call_types.h>
+#include <linux/objtool_types.h>
int main(void)
{
@@ -37,6 +38,9 @@ int main(void)
#endif
#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
DEFINE(STATIC_CALL_TRAMP_KEY_SIZE, sizeof(struct static_call_tramp_key));
+#endif
+#ifdef CONFIG_OBJTOOL
+ DEFINE(UNWIND_HINT_SIZE, sizeof(struct unwind_hint));
#endif
/* End of constants */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 49/64] objtool: Unify STACK_FRAME_NON_STANDARD entry sizes
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (47 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 48/64] x86/orc: Define ELF section entry size for unwind hints Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 50/64] objtool/klp: Add --checksum option to generate per-function checksums Josh Poimboeuf
` (14 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The C implementation of STACK_FRAME_NON_STANDARD emits 8-byte entries,
whereas the asm version's entries are only 4 bytes.
Make them consistent by converting the asm version to 8-byte entries.
This is much easier than converting the C version to 4-bytes, which
would require awkwardly putting inline asm in a dummy function in order
to pass the 'func' pointer to the asm.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/linux/objtool.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index c7a3851ae4ae..7d7bb7f1af69 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -106,7 +106,7 @@
.macro STACK_FRAME_NON_STANDARD func:req
.pushsection .discard.func_stack_frame_non_standard, "aw"
- .long \func - .
+ .quad \func
.popsection
.endm
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 50/64] objtool/klp: Add --checksum option to generate per-function checksums
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (48 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 49/64] objtool: Unify STACK_FRAME_NON_STANDARD entry sizes Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 51/64] objtool/klp: Add --debug-checksum=<funcs> to show per-instruction checksums Josh Poimboeuf
` (13 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for the objtool klp diff subcommand, add a command-line
option to generate a unique checksum for each function. This will
enable detection of functions which have changed between two versions of
an object file.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/Makefile | 38 +++--
tools/objtool/builtin-check.c | 12 +-
tools/objtool/check.c | 140 +++++++++++++++++-
tools/objtool/elf.c | 46 +++++-
tools/objtool/include/objtool/builtin.h | 3 +-
tools/objtool/include/objtool/check.h | 5 +-
tools/objtool/include/objtool/checksum.h | 42 ++++++
.../objtool/include/objtool/checksum_types.h | 25 ++++
tools/objtool/include/objtool/elf.h | 5 +-
tools/objtool/include/objtool/objtool.h | 2 +
10 files changed, 292 insertions(+), 26 deletions(-)
create mode 100644 tools/objtool/include/objtool/checksum.h
create mode 100644 tools/objtool/include/objtool/checksum_types.h
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index fc82d47f2b9a..958761c05b7c 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -2,6 +2,27 @@
include ../scripts/Makefile.include
include ../scripts/Makefile.arch
+ifeq ($(SRCARCH),x86)
+ BUILD_ORC := y
+ ARCH_HAS_KLP := y
+endif
+
+ifeq ($(SRCARCH),loongarch)
+ BUILD_ORC := y
+endif
+
+ifeq ($(ARCH_HAS_KLP),y)
+ HAVE_XXHASH = $(shell echo "int main() {}" | \
+ $(HOSTCC) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n)
+ ifeq ($(HAVE_XXHASH),y)
+ LIBXXHASH_CFLAGS := $(shell $(HOSTPKG_CONFIG) libxxhash --cflags 2>/dev/null) \
+ -DBUILD_KLP
+ LIBXXHASH_LIBS := $(shell $(HOSTPKG_CONFIG) libxxhash --libs 2>/dev/null || echo -lxxhash)
+ endif
+endif
+
+export BUILD_ORC
+
ifeq ($(srctree),)
srctree := $(patsubst %/,%,$(dir $(CURDIR)))
srctree := $(patsubst %/,%,$(dir $(srctree)))
@@ -36,10 +57,10 @@ INCLUDES := -I$(srctree)/tools/include \
-I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \
-I$(LIBSUBCMD_OUTPUT)/include
-OBJTOOL_CFLAGS := -std=gnu11 -fomit-frame-pointer -O2 -g \
- $(WARNINGS) $(INCLUDES) $(LIBELF_FLAGS) $(HOSTCFLAGS)
+OBJTOOL_CFLAGS := -std=gnu11 -fomit-frame-pointer -O2 -g $(WARNINGS) \
+ $(INCLUDES) $(LIBELF_FLAGS) $(LIBXXHASH_CFLAGS) $(HOSTCFLAGS)
-OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(HOSTLDFLAGS)
+OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(LIBXXHASH_LIBS) $(HOSTLDFLAGS)
# Allow old libelf to be used:
elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - 2>/dev/null | grep elf_getshdr)
@@ -51,17 +72,6 @@ HOST_OVERRIDES := CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)"
AWK = awk
MKDIR = mkdir
-BUILD_ORC := n
-
-ifeq ($(SRCARCH),x86)
- BUILD_ORC := y
-endif
-
-ifeq ($(SRCARCH),loongarch)
- BUILD_ORC := y
-endif
-
-export BUILD_ORC
export srctree OUTPUT CFLAGS SRCARCH AWK
include $(srctree)/tools/build/Makefile.include
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 3172f7e98147..331c6e1dc04c 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -73,6 +73,7 @@ static int parse_hacks(const struct option *opt, const char *str, int unset)
static const struct option check_options[] = {
OPT_GROUP("Actions:"),
+ OPT_BOOLEAN(0, "checksum", &opts.checksum, "generate per-function checksums"),
OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
@@ -159,7 +160,16 @@ static bool opts_valid(void)
return false;
}
- if (opts.hack_jump_label ||
+
+#ifndef BUILD_KLP
+ if (opts.checksum) {
+ ERROR("--checksum not supported; install xxhash-devel and recompile");
+ return false;
+ }
+#endif
+
+ if (opts.checksum ||
+ opts.hack_jump_label ||
opts.hack_noinstr ||
opts.ibt ||
opts.mcount ||
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c3e1ca3dba06..fd7e470f01bd 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -15,6 +15,7 @@
#include <objtool/special.h>
#include <objtool/warn.h>
#include <objtool/endianness.h>
+#include <objtool/checksum.h>
#include <linux/objtool_types.h>
#include <linux/hashtable.h>
@@ -978,6 +979,59 @@ static int create_direct_call_sections(struct objtool_file *file)
return 0;
}
+#ifdef BUILD_KLP
+static int create_sym_checksum_section(struct objtool_file *file)
+{
+ struct section *sec;
+ struct symbol *sym;
+ unsigned int idx = 0;
+ struct sym_checksum *checksum;
+ size_t entsize = sizeof(struct sym_checksum);
+
+ sec = find_section_by_name(file->elf, SYM_CHECKSUM_SEC);
+ if (sec) {
+ if (!opts.dryrun)
+ WARN("file already has " SYM_CHECKSUM_SEC " section, skipping");
+
+ return 0;
+ }
+
+ for_each_sym(file->elf, sym)
+ if (sym->csum.checksum)
+ idx++;
+
+ if (!idx)
+ return 0;
+
+ sec = elf_create_section_pair(file->elf, ".discard.sym_checksum", entsize,
+ idx, idx);
+ if (!sec)
+ return -1;
+
+ idx = 0;
+ for_each_sym(file->elf, sym) {
+ if (!sym->csum.checksum)
+ continue;
+
+ if (!elf_init_reloc(file->elf, sec->rsec, idx, idx * entsize,
+ sym, 0, R_TEXT64))
+ return -1;
+
+ checksum = (struct sym_checksum *)sec->data->d_buf + idx;
+ checksum->addr = 0; /* reloc */
+ checksum->checksum = sym->csum.checksum;
+
+ mark_sec_changed(file->elf, sec, true);
+
+ idx++;
+ }
+
+ return 0;
+}
+#else
+static int create_sym_checksum_section(struct objtool_file *file) { return -EINVAL; }
+#endif
+
/*
* Warnings shouldn't be reported for ignored functions.
*/
@@ -1755,6 +1809,7 @@ static int handle_group_alt(struct objtool_file *file,
nop->type = INSN_NOP;
nop->sym = orig_insn->sym;
nop->alt_group = new_alt_group;
+ nop->fake = 1;
}
if (!special_alt->new_len) {
@@ -2524,6 +2579,14 @@ static void mark_holes(struct objtool_file *file)
}
}
+static bool validate_branch_enabled(void)
+{
+ return opts.stackval ||
+ opts.orc ||
+ opts.uaccess ||
+ opts.checksum;
+}
+
static int decode_sections(struct objtool_file *file)
{
mark_rodata(file);
@@ -2552,7 +2615,7 @@ static int decode_sections(struct objtool_file *file)
* Must be before add_jump_destinations(), which depends on 'func'
* being set for alternatives, to enable proper sibling call detection.
*/
- if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
+ if (validate_branch_enabled() || opts.noinstr) {
if (add_special_section_alts(file))
return -1;
}
@@ -3524,6 +3587,50 @@ static bool skip_alt_group(struct instruction *insn)
return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
}
+static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
+ struct instruction *insn)
+{
+ struct reloc *reloc = insn_reloc(file, insn);
+ unsigned long offset;
+ struct symbol *sym;
+
+ if (insn->fake)
+ return;
+
+ checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);
+
+ if (!reloc) {
+ struct symbol *call_dest = insn_call_dest(insn);
+
+ if (call_dest)
+ checksum_update(func, insn, call_dest->demangled_name,
+ strlen(call_dest->demangled_name));
+ return;
+ }
+
+ sym = reloc->sym;
+ offset = arch_insn_adjusted_addend(insn, reloc);
+
+ if (is_string_sec(sym->sec)) {
+ char *str;
+
+ str = sym->sec->data->d_buf + sym->offset + offset;
+ checksum_update(func, insn, str, strlen(str));
+ return;
+ }
+
+ if (is_sec_sym(sym)) {
+ sym = find_symbol_containing(reloc->sym->sec, offset);
+ if (!sym)
+ return;
+
+ offset -= sym->offset;
+ }
+
+ checksum_update(func, insn, sym->demangled_name, strlen(sym->demangled_name));
+ checksum_update(func, insn, &offset, sizeof(offset));
+}
+
/*
* Follow the branch starting at the given instruction, and recursively follow
* any other branches (jumps). Meanwhile, track the frame pointer state at
@@ -3544,6 +3651,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
while (1) {
next_insn = next_insn_to_validate(file, insn);
+ if (opts.checksum && func && insn->sec)
+ checksum_update_insn(file, func, insn);
+
if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
/* Ignore KCFI type preambles, which always fall through */
if (is_prefix_func(func))
@@ -3793,7 +3903,13 @@ static int validate_unwind_hint(struct objtool_file *file,
struct insn_state *state)
{
if (insn->hint && !insn->visited) {
- int ret = validate_branch(file, insn_func(insn), insn, *state);
+ struct symbol *func = insn_func(insn);
+ int ret;
+
+ if (opts.checksum)
+ checksum_init(func);
+
+ ret = validate_branch(file, func, insn, *state);
if (ret)
BT_INSN(insn, "<=== (hint)");
return ret;
@@ -4141,6 +4257,7 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
struct symbol *sym, struct insn_state *state)
{
struct instruction *insn;
+ struct symbol *func;
int ret;
if (!sym->len) {
@@ -4158,9 +4275,18 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
if (opts.uaccess)
state->uaccess = sym->uaccess_safe;
- ret = validate_branch(file, insn_func(insn), insn, *state);
+ func = insn_func(insn);
+
+ if (opts.checksum)
+ checksum_init(func);
+
+ ret = validate_branch(file, func, insn, *state);
if (ret)
BT_INSN(insn, "<=== (sym)");
+
+ if (opts.checksum)
+ checksum_finish(func);
+
return ret;
}
@@ -4637,7 +4763,7 @@ int check(struct objtool_file *file)
if (opts.retpoline)
warnings += validate_retpoline(file);
- if (opts.stackval || opts.orc || opts.uaccess) {
+ if (validate_branch_enabled()) {
int w = 0;
w += validate_functions(file);
@@ -4713,6 +4839,12 @@ int check(struct objtool_file *file)
goto out;
}
+ if (opts.checksum) {
+ ret = create_sym_checksum_section(file);
+ if (ret)
+ goto out;
+ }
+
if (opts.orc && nr_insns) {
ret = orc_create(file);
if (ret)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index b88190fe7131..d2f418a34881 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -17,6 +17,7 @@
#include <unistd.h>
#include <errno.h>
#include <libgen.h>
+#include <ctype.h>
#include <linux/interval_tree_generic.h>
#include <objtool/builtin.h>
#include <objtool/elf.h>
@@ -412,7 +413,38 @@ static int read_sections(struct elf *elf)
return 0;
}
-static void elf_add_symbol(struct elf *elf, struct symbol *sym)
+static const char *demangle_name(struct symbol *sym)
+{
+ char *str;
+
+ if (!is_local_sym(sym))
+ return sym->name;
+
+ if (!is_func_sym(sym) && !is_object_sym(sym))
+ return sym->name;
+
+ if (!strstarts(sym->name, "__UNIQUE_ID_") && !strchr(sym->name, '.'))
+ return sym->name;
+
+ str = strdup(sym->name);
+ if (!str) {
+ ERROR_GLIBC("strdup");
+ return NULL;
+ }
+
+ for (int i = strlen(str) - 1; i >= 0; i--) {
+ char c = str[i];
+
+ if (!isdigit(c) && c != '.') {
+ str[i + 1] = '\0';
+ break;
+ }
+ };
+
+ return str;
+}
+
+static int elf_add_symbol(struct elf *elf, struct symbol *sym)
{
struct list_head *entry;
struct rb_node *pnode;
@@ -453,6 +485,12 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
if (is_func_sym(sym) && strstr(sym->name, ".cold"))
sym->cold = 1;
sym->pfunc = sym->cfunc = sym;
+
+ sym->demangled_name = demangle_name(sym);
+ if (!sym->demangled_name)
+ return -1;
+
+ return 0;
}
static int read_symbols(struct elf *elf)
@@ -526,7 +564,8 @@ static int read_symbols(struct elf *elf)
} else
sym->sec = find_section_by_index(elf, 0);
- elf_add_symbol(elf, sym);
+ if (elf_add_symbol(elf, sym))
+ return -1;
}
if (opts.stats) {
@@ -864,7 +903,8 @@ struct symbol *elf_create_symbol(struct elf *elf, const char *name,
mark_sec_changed(elf, symtab_shndx, true);
}
- elf_add_symbol(elf, sym);
+ if (elf_add_symbol(elf, sym))
+ return NULL;
return sym;
}
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index de6c08f8e060..06083e8c5c91 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -9,6 +9,7 @@
struct opts {
/* actions: */
+ bool cfi;
bool dump_orc;
bool hack_jump_label;
bool hack_noinstr;
@@ -23,9 +24,9 @@ struct opts {
bool sls;
bool stackval;
bool static_call;
+ bool checksum;
bool uaccess;
int prefix;
- bool cfi;
/* options: */
bool backtrace;
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 0f4e7ac929ef..d73b0c3ae1ee 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -65,8 +65,9 @@ struct instruction {
unret : 1,
visited : 4,
no_reloc : 1,
- hole : 1;
- /* 10 bit hole */
+ hole : 1,
+ fake : 1;
+ /* 9 bit hole */
struct alt_group *alt_group;
struct instruction *jump_dest;
diff --git a/tools/objtool/include/objtool/checksum.h b/tools/objtool/include/objtool/checksum.h
new file mode 100644
index 000000000000..927ca74b5c39
--- /dev/null
+++ b/tools/objtool/include/objtool/checksum.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _OBJTOOL_CHECKSUM_H
+#define _OBJTOOL_CHECKSUM_H
+
+#include <objtool/elf.h>
+
+#ifdef BUILD_KLP
+
+static inline void checksum_init(struct symbol *func)
+{
+ if (func && !func->csum.state) {
+ func->csum.state = XXH3_createState();
+ XXH3_64bits_reset(func->csum.state);
+ }
+}
+
+static inline void checksum_update(struct symbol *func,
+ struct instruction *insn,
+ const void *data, size_t size)
+{
+ XXH3_64bits_update(func->csum.state, data, size);
+}
+
+static inline void checksum_finish(struct symbol *func)
+{
+ if (func && func->csum.state) {
+ func->csum.checksum = XXH3_64bits_digest(func->csum.state);
+ func->csum.state = NULL;
+ }
+}
+
+#else /* !BUILD_KLP */
+
+static inline void checksum_init(struct symbol *func) {}
+static inline void checksum_update(struct symbol *func,
+ struct instruction *insn,
+ const void *data, size_t size) {}
+static inline void checksum_finish(struct symbol *func) {}
+
+#endif /* !BUILD_KLP */
+
+#endif /* _OBJTOOL_CHECKSUM_H */
diff --git a/tools/objtool/include/objtool/checksum_types.h b/tools/objtool/include/objtool/checksum_types.h
new file mode 100644
index 000000000000..507efdd8ab5b
--- /dev/null
+++ b/tools/objtool/include/objtool/checksum_types.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _OBJTOOL_CHECKSUM_TYPES_H
+#define _OBJTOOL_CHECKSUM_TYPES_H
+
+struct sym_checksum {
+ u64 addr;
+ u64 checksum;
+};
+
+#ifdef BUILD_KLP
+
+#include <xxhash.h>
+
+struct checksum {
+ XXH3_state_t *state;
+ XXH64_hash_t checksum;
+};
+
+#else /* !BUILD_KLP */
+
+struct checksum {};
+
+#endif /* !BUILD_KLP */
+
+#endif /* _OBJTOOL_CHECKSUM_TYPES_H */
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index a0fc252e1993..4d1023fdb700 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -13,6 +13,8 @@
#include <linux/hashtable.h>
#include <linux/rbtree.h>
#include <linux/jhash.h>
+
+#include <objtool/checksum_types.h>
#include <arch/elf.h>
#define SYM_NAME_LEN 512
@@ -57,7 +59,7 @@ struct symbol {
struct elf_hash_node name_hash;
GElf_Sym sym;
struct section *sec;
- const char *name;
+ const char *name, *demangled_name;
unsigned int idx, len;
unsigned long offset;
unsigned long __subtree_last;
@@ -79,6 +81,7 @@ struct symbol {
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;
+ struct checksum csum;
};
struct reloc {
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index c0dc86a78ff6..90c591b5bd68 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -14,6 +14,8 @@
#define __weak __attribute__((weak))
+#define SYM_CHECKSUM_SEC ".discard.sym_checksum"
+
struct pv_state {
bool clean;
struct list_head targets;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 51/64] objtool/klp: Add --debug-checksum=<funcs> to show per-instruction checksums
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (49 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 50/64] objtool/klp: Add --checksum option to generate per-function checksums Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 52/64] objtool/klp: Introduce klp diff subcommand for diffing object files Josh Poimboeuf
` (12 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a --debug-checksum=<funcs> option to the check subcommand to print
the calculated checksum of each instruction in the given functions.
This is useful for determining where two versions of a function begin to
diverge.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/builtin-check.c | 6 ++++
tools/objtool/check.c | 42 ++++++++++++++++++++++++
tools/objtool/include/objtool/builtin.h | 1 +
tools/objtool/include/objtool/checksum.h | 1 +
tools/objtool/include/objtool/elf.h | 1 +
tools/objtool/include/objtool/warn.h | 19 +++++++++++
6 files changed, 70 insertions(+)
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 331c6e1dc04c..cd2c4a387100 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -93,6 +93,7 @@ static const struct option check_options[] = {
OPT_GROUP("Options:"),
OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),
OPT_BOOLEAN(0, "backup", &opts.backup, "create backup (.orig) file on warning/error"),
+ OPT_STRING(0, "debug-checksum", &opts.debug_checksum, "funcs", "enable checksum debug output"),
OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"),
OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),
@@ -168,6 +169,11 @@ static bool opts_valid(void)
}
#endif
+ if (opts.debug_checksum && !opts.checksum) {
+ ERROR("--debug-checksum requires --checksum");
+ return false;
+ }
+
if (opts.checksum ||
opts.hack_jump_label ||
opts.hack_noinstr ||
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index fd7e470f01bd..7e492945e5e5 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3587,6 +3587,44 @@ static bool skip_alt_group(struct instruction *insn)
return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
}
+static int checksum_debug_init(struct objtool_file *file)
+{
+ char *dup, *s;
+
+ if (!opts.debug_checksum)
+ return 0;
+
+ dup = strdup(opts.debug_checksum);
+ if (!dup) {
+ ERROR_GLIBC("strdup");
+ return -1;
+ }
+
+ s = dup;
+ while (*s) {
+ struct symbol *func;
+ char *comma;
+
+ comma = strchr(s, ',');
+ if (comma)
+ *comma = '\0';
+
+ func = find_symbol_by_name(file->elf, s);
+ if (!func || !is_func_sym(func))
+ WARN("--debug-checksum: can't find '%s'", s);
+ else
+ func->debug_checksum = 1;
+
+ if (!comma)
+ break;
+
+ s = comma + 1;
+ }
+
+ free(dup);
+ return 0;
+}
+
static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
struct instruction *insn)
{
@@ -4753,6 +4791,10 @@ int check(struct objtool_file *file)
cfi_hash_add(&init_cfi);
cfi_hash_add(&func_cfi);
+ ret = checksum_debug_init(file);
+ if (ret)
+ goto out;
+
ret = decode_sections(file);
if (ret)
goto out;
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 06083e8c5c91..92bc7089cfc1 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -31,6 +31,7 @@ struct opts {
/* options: */
bool backtrace;
bool backup;
+ const char *debug_checksum;
bool dryrun;
bool link;
bool mnop;
diff --git a/tools/objtool/include/objtool/checksum.h b/tools/objtool/include/objtool/checksum.h
index 927ca74b5c39..7fe21608722a 100644
--- a/tools/objtool/include/objtool/checksum.h
+++ b/tools/objtool/include/objtool/checksum.h
@@ -19,6 +19,7 @@ static inline void checksum_update(struct symbol *func,
const void *data, size_t size)
{
XXH3_64bits_update(func->csum.state, data, size);
+ dbg_checksum(func, insn, XXH3_64bits_digest(func->csum.state));
}
static inline void checksum_finish(struct symbol *func)
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 4d1023fdb700..4cfd09e66cb5 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -78,6 +78,7 @@ struct symbol {
u8 ignore : 1;
u8 cold : 1;
u8 prefix : 1;
+ u8 debug_checksum : 1;
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;
diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index cb8fe846d9dd..29173a1368d7 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -102,4 +102,23 @@ static inline char *offstr(struct section *sec, unsigned long offset)
#define ERROR_FUNC(sec, offset, format, ...) __WARN_FUNC(ERROR_STR, sec, offset, format, ##__VA_ARGS__)
#define ERROR_INSN(insn, format, ...) WARN_FUNC(insn->sec, insn->offset, format, ##__VA_ARGS__)
+
+#define __dbg(format, ...) \
+ fprintf(stderr, \
+ "DEBUG: %s%s" format "\n", \
+ objname ?: "", \
+ objname ? ": " : "", \
+ ##__VA_ARGS__)
+
+#define dbg_checksum(func, insn, checksum) \
+({ \
+ if (unlikely(insn->sym && insn->sym->pfunc && \
+ insn->sym->pfunc->debug_checksum)) { \
+ char *insn_off = offstr(insn->sec, insn->offset); \
+ __dbg("checksum: %s %s %016lx", \
+ func->name, insn_off, checksum); \
+ free(insn_off); \
+ } \
+})
+
#endif /* _WARN_H */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 52/64] objtool/klp: Introduce klp diff subcommand for diffing object files
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (50 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 51/64] objtool/klp: Add --debug-checksum=<funcs> to show per-instruction checksums Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 53/64] objtool/klp: Add --debug option to show cloning decisions Josh Poimboeuf
` (11 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a new klp diff subcommand which performs a binary diff between two
object files and extracts changed functions into a new object which can
then be linked into a livepatch module.
This builds on concepts from the longstanding out-of-tree kpatch [1]
project which began in 2012 and has been used for many years to generate
livepatch modules for production kernels. However, this is a complete
rewrite which incorporates hard-earned lessons from 12+ years of
maintaining kpatch.
Key improvements compared to kpatch-build:
- Integrated with objtool: Leverages objtool's existing control-flow
graph analysis to help detect changed functions.
- Works on vmlinux.o: Supports late-linked objects, making it
compatible with LTO, IBT, and similar.
- Simplified code base: ~3k fewer lines of code.
- Upstream: No more out-of-tree #ifdef hacks, far less cruft.
- Cleaner internals: Vastly simplified logic for symbol/section/reloc
inclusion and special section extraction.
- Robust __LINE__ macro handling: Avoids false positive binary diffs
caused by the __LINE__ macro by introducing a fix-patch-lines script
(coming in a later patch) which injects #line directives into the
source .patch to preserve the original line numbers at compile time.
Note the end result of this subcommand is not yet functionally complete.
Livepatch needs some ELF magic which linkers don't like:
- Two relocation sections (.rela*, .klp.rela*) for the same text
section.
- Use of SHN_LIVEPATCH to mark livepatch symbols.
Unfortunately linkers tend to mangle such things. To work around that,
klp diff generates a linker-compliant intermediate binary which encodes
the relevant KLP section/reloc/symbol metadata.
After module linking, a klp post-link step (coming soon) will clean up
the mess and convert the linked .ko into a fully compliant livepatch
module.
Note this subcommand requires the diffed binaries to have been compiled
with -ffunction-sections and -fdata-sections, and processed with
'objtool --checksum'. Those constraints will be handled by a klp-build
script introduced in a later patch.
Without '-ffunction-sections -fdata-sections', reliable object diffing
would be infeasible due to toolchain limitations:
- For intra-file+intra-section references, the compiler might
occasionally generated hard-coded instruction offsets instead of
relocations.
- Section-symbol-based references can be ambiguous:
- Overlapping or zero-length symbols create ambiguity as to which
symbol is being referenced.
- A reference to the end of a symbol (e.g., checking array bounds)
can be misinterpreted as a reference to the next symbol, or vice
versa.
A potential future alternative to '-ffunction-sections -fdata-sections'
would be to introduce a toolchain option that forces symbol-based
(non-section) relocations.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
MAINTAINERS | 2 +-
include/linux/livepatch.h | 25 +-
include/linux/livepatch_external.h | 76 +
kernel/livepatch/core.c | 4 +-
scripts/module.lds.S | 10 +-
tools/include/linux/livepatch_external.h | 76 +
tools/include/linux/string.h | 14 +
tools/objtool/Build | 4 +-
tools/objtool/Makefile | 3 +-
tools/objtool/arch/x86/decode.c | 40 +
tools/objtool/builtin-klp.c | 52 +
tools/objtool/check.c | 14 -
tools/objtool/elf.c | 21 +-
tools/objtool/include/objtool/arch.h | 1 +
tools/objtool/include/objtool/builtin.h | 2 +
tools/objtool/include/objtool/elf.h | 52 +-
tools/objtool/include/objtool/klp.h | 31 +
tools/objtool/include/objtool/objtool.h | 2 +
tools/objtool/include/objtool/util.h | 19 +
tools/objtool/klp-diff.c | 1600 ++++++++++++++++++++++
tools/objtool/objtool.c | 41 +-
tools/objtool/sync-check.sh | 1 +
tools/objtool/weak.c | 7 +
23 files changed, 2038 insertions(+), 59 deletions(-)
create mode 100644 include/linux/livepatch_external.h
create mode 100644 tools/include/linux/livepatch_external.h
create mode 100644 tools/objtool/builtin-klp.c
create mode 100644 tools/objtool/include/objtool/klp.h
create mode 100644 tools/objtool/include/objtool/util.h
create mode 100644 tools/objtool/klp-diff.c
diff --git a/MAINTAINERS b/MAINTAINERS
index efb51ee92683..0298d9570ca8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14002,7 +14002,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching.g
F: Documentation/ABI/testing/sysfs-kernel-livepatch
F: Documentation/livepatch/
F: arch/powerpc/include/asm/livepatch.h
-F: include/linux/livepatch.h
+F: include/linux/livepatch*.h
F: kernel/livepatch/
F: kernel/module/livepatch.c
F: samples/livepatch/
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 51a258c24ff5..772919e8096a 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -13,6 +13,7 @@
#include <linux/ftrace.h>
#include <linux/completion.h>
#include <linux/list.h>
+#include <linux/livepatch_external.h>
#include <linux/livepatch_sched.h>
#if IS_ENABLED(CONFIG_LIVEPATCH)
@@ -77,30 +78,6 @@ struct klp_func {
bool transition;
};
-struct klp_object;
-
-/**
- * struct klp_callbacks - pre/post live-(un)patch callback structure
- * @pre_patch: executed before code patching
- * @post_patch: executed after code patching
- * @pre_unpatch: executed before code unpatching
- * @post_unpatch: executed after code unpatching
- * @post_unpatch_enabled: flag indicating if post-unpatch callback
- * should run
- *
- * All callbacks are optional. Only the pre-patch callback, if provided,
- * will be unconditionally executed. If the parent klp_object fails to
- * patch for any reason, including a non-zero error status returned from
- * the pre-patch callback, no further callbacks will be executed.
- */
-struct klp_callbacks {
- int (*pre_patch)(struct klp_object *obj);
- void (*post_patch)(struct klp_object *obj);
- void (*pre_unpatch)(struct klp_object *obj);
- void (*post_unpatch)(struct klp_object *obj);
- bool post_unpatch_enabled;
-};
-
/**
* struct klp_object - kernel object structure for live patching
* @name: module name (or NULL for vmlinux)
diff --git a/include/linux/livepatch_external.h b/include/linux/livepatch_external.h
new file mode 100644
index 000000000000..138af19b0f5c
--- /dev/null
+++ b/include/linux/livepatch_external.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * External livepatch interfaces for patch creation tooling
+ */
+
+#ifndef _LINUX_LIVEPATCH_EXTERNAL_H_
+#define _LINUX_LIVEPATCH_EXTERNAL_H_
+
+#include <linux/types.h>
+
+#define KLP_RELOC_SEC_PREFIX ".klp.rela."
+#define KLP_SYM_PREFIX ".klp.sym."
+
+#define __KLP_PRE_PATCH_PREFIX __klp_pre_patch_callback_
+#define __KLP_POST_PATCH_PREFIX __klp_post_patch_callback_
+#define __KLP_PRE_UNPATCH_PREFIX __klp_pre_unpatch_callback_
+#define __KLP_POST_UNPATCH_PREFIX __klp_post_unpatch_callback_
+
+#define KLP_PRE_PATCH_PREFIX __stringify(__KLP_PRE_PATCH_PREFIX)
+#define KLP_POST_PATCH_PREFIX __stringify(__KLP_POST_PATCH_PREFIX)
+#define KLP_PRE_UNPATCH_PREFIX __stringify(__KLP_PRE_UNPATCH_PREFIX)
+#define KLP_POST_UNPATCH_PREFIX __stringify(__KLP_POST_UNPATCH_PREFIX)
+
+struct klp_object;
+
+typedef int (*klp_pre_patch_t)(struct klp_object *obj);
+typedef void (*klp_post_patch_t)(struct klp_object *obj);
+typedef void (*klp_pre_unpatch_t)(struct klp_object *obj);
+typedef void (*klp_post_unpatch_t)(struct klp_object *obj);
+
+/**
+ * struct klp_callbacks - pre/post live-(un)patch callback structure
+ * @pre_patch: executed before code patching
+ * @post_patch: executed after code patching
+ * @pre_unpatch: executed before code unpatching
+ * @post_unpatch: executed after code unpatching
+ * @post_unpatch_enabled: flag indicating if post-unpatch callback
+ * should run
+ *
+ * All callbacks are optional. Only the pre-patch callback, if provided,
+ * will be unconditionally executed. If the parent klp_object fails to
+ * patch for any reason, including a non-zero error status returned from
+ * the pre-patch callback, no further callbacks will be executed.
+ */
+struct klp_callbacks {
+ klp_pre_patch_t pre_patch;
+ klp_post_patch_t post_patch;
+ klp_pre_unpatch_t pre_unpatch;
+ klp_post_unpatch_t post_unpatch;
+ bool post_unpatch_enabled;
+};
+
+/*
+ * 'struct klp_{func,object}_ext' are compact "external" representations of
+ * 'struct klp_{func,object}'. They are used by objtool for livepatch
+ * generation. The structs are then read by the livepatch module and converted
+ * to the real structs before calling klp_enable_patch().
+ *
+ * TODO make these the official API for klp_enable_patch(). That should
+ * simplify livepatch's interface as well as its data structure lifetime
+ * management.
+ */
+struct klp_func_ext {
+ const char *old_name;
+ void *new_func;
+ unsigned long sympos;
+};
+
+struct klp_object_ext {
+ const char *name;
+ struct klp_func_ext *funcs;
+ struct klp_callbacks callbacks;
+ unsigned int nr_funcs;
+};
+
+#endif /* _LINUX_LIVEPATCH_EXTERNAL_H_ */
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 7e443c2cf7d4..0044a8125013 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -224,7 +224,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
/* Format: .klp.sym.sym_objname.sym_name,sympos */
cnt = sscanf(strtab + sym->st_name,
- ".klp.sym.%55[^.].%511[^,],%lu",
+ KLP_SYM_PREFIX "%55[^.].%511[^,],%lu",
sym_objname, sym_name, &sympos);
if (cnt != 3) {
pr_err("symbol %s has an incorrectly formatted name\n",
@@ -303,7 +303,7 @@ static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
* See comment in klp_resolve_symbols() for an explanation
* of the selected field width value.
*/
- cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]",
+ cnt = sscanf(shstrtab + sec->sh_name, KLP_RELOC_SEC_PREFIX "%55[^.]",
sec_objname);
if (cnt != 1) {
pr_err("section %s has an incorrectly formatted name\n",
diff --git a/scripts/module.lds.S b/scripts/module.lds.S
index 0b5ea63d1c67..05abb3ceabef 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -34,8 +34,16 @@ SECTIONS {
__patchable_function_entries : { *(__patchable_function_entries) }
+ __klp_funcs 0: ALIGN(8) { KEEP(*(__klp_funcs)) }
+
+ __klp_objects 0: ALIGN(8) {
+ __start_klp_objects = .;
+ KEEP(*(__klp_objects))
+ __stop_klp_objects = .;
+ }
+
#ifdef CONFIG_ARCH_USES_CFI_TRAPS
- __kcfi_traps : { KEEP(*(.kcfi_traps)) }
+ __kcfi_traps : { KEEP(*(.kcfi_traps)) }
#endif
.text : {
diff --git a/tools/include/linux/livepatch_external.h b/tools/include/linux/livepatch_external.h
new file mode 100644
index 000000000000..138af19b0f5c
--- /dev/null
+++ b/tools/include/linux/livepatch_external.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * External livepatch interfaces for patch creation tooling
+ */
+
+#ifndef _LINUX_LIVEPATCH_EXTERNAL_H_
+#define _LINUX_LIVEPATCH_EXTERNAL_H_
+
+#include <linux/types.h>
+
+#define KLP_RELOC_SEC_PREFIX ".klp.rela."
+#define KLP_SYM_PREFIX ".klp.sym."
+
+#define __KLP_PRE_PATCH_PREFIX __klp_pre_patch_callback_
+#define __KLP_POST_PATCH_PREFIX __klp_post_patch_callback_
+#define __KLP_PRE_UNPATCH_PREFIX __klp_pre_unpatch_callback_
+#define __KLP_POST_UNPATCH_PREFIX __klp_post_unpatch_callback_
+
+#define KLP_PRE_PATCH_PREFIX __stringify(__KLP_PRE_PATCH_PREFIX)
+#define KLP_POST_PATCH_PREFIX __stringify(__KLP_POST_PATCH_PREFIX)
+#define KLP_PRE_UNPATCH_PREFIX __stringify(__KLP_PRE_UNPATCH_PREFIX)
+#define KLP_POST_UNPATCH_PREFIX __stringify(__KLP_POST_UNPATCH_PREFIX)
+
+struct klp_object;
+
+typedef int (*klp_pre_patch_t)(struct klp_object *obj);
+typedef void (*klp_post_patch_t)(struct klp_object *obj);
+typedef void (*klp_pre_unpatch_t)(struct klp_object *obj);
+typedef void (*klp_post_unpatch_t)(struct klp_object *obj);
+
+/**
+ * struct klp_callbacks - pre/post live-(un)patch callback structure
+ * @pre_patch: executed before code patching
+ * @post_patch: executed after code patching
+ * @pre_unpatch: executed before code unpatching
+ * @post_unpatch: executed after code unpatching
+ * @post_unpatch_enabled: flag indicating if post-unpatch callback
+ * should run
+ *
+ * All callbacks are optional. Only the pre-patch callback, if provided,
+ * will be unconditionally executed. If the parent klp_object fails to
+ * patch for any reason, including a non-zero error status returned from
+ * the pre-patch callback, no further callbacks will be executed.
+ */
+struct klp_callbacks {
+ klp_pre_patch_t pre_patch;
+ klp_post_patch_t post_patch;
+ klp_pre_unpatch_t pre_unpatch;
+ klp_post_unpatch_t post_unpatch;
+ bool post_unpatch_enabled;
+};
+
+/*
+ * 'struct klp_{func,object}_ext' are compact "external" representations of
+ * 'struct klp_{func,object}'. They are used by objtool for livepatch
+ * generation. The structs are then read by the livepatch module and converted
+ * to the real structs before calling klp_enable_patch().
+ *
+ * TODO make these the official API for klp_enable_patch(). That should
+ * simplify livepatch's interface as well as its data structure lifetime
+ * management.
+ */
+struct klp_func_ext {
+ const char *old_name;
+ void *new_func;
+ unsigned long sympos;
+};
+
+struct klp_object_ext {
+ const char *name;
+ struct klp_func_ext *funcs;
+ struct klp_callbacks callbacks;
+ unsigned int nr_funcs;
+};
+
+#endif /* _LINUX_LIVEPATCH_EXTERNAL_H_ */
diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index 8499f509f03e..51ad3cf4fa82 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -44,6 +44,20 @@ static inline bool strstarts(const char *str, const char *prefix)
return strncmp(str, prefix, strlen(prefix)) == 0;
}
+/*
+ * Checks if a string ends with another.
+ */
+static inline bool str_ends_with(const char *str, const char *substr)
+{
+ size_t len = strlen(str);
+ size_t sublen = strlen(substr);
+
+ if (sublen > len)
+ return false;
+
+ return !strcmp(str + len - sublen, substr);
+}
+
extern char * __must_check skip_spaces(const char *);
extern char *strim(char *);
diff --git a/tools/objtool/Build b/tools/objtool/Build
index a3cdf8af6635..0b01657671d7 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -8,8 +8,8 @@ objtool-y += builtin-check.o
objtool-y += elf.o
objtool-y += objtool.o
-objtool-$(BUILD_ORC) += orc_gen.o
-objtool-$(BUILD_ORC) += orc_dump.o
+objtool-$(BUILD_ORC) += orc_gen.o orc_dump.o
+objtool-$(BUILD_KLP) += builtin-klp.o klp-diff.o
objtool-y += libstring.o
objtool-y += libctype.o
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 958761c05b7c..48928c9bebef 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -15,13 +15,14 @@ ifeq ($(ARCH_HAS_KLP),y)
HAVE_XXHASH = $(shell echo "int main() {}" | \
$(HOSTCC) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n)
ifeq ($(HAVE_XXHASH),y)
+ BUILD_KLP := y
LIBXXHASH_CFLAGS := $(shell $(HOSTPKG_CONFIG) libxxhash --cflags 2>/dev/null) \
-DBUILD_KLP
LIBXXHASH_LIBS := $(shell $(HOSTPKG_CONFIG) libxxhash --libs 2>/dev/null || echo -lxxhash)
endif
endif
-export BUILD_ORC
+export BUILD_ORC BUILD_KLP
ifeq ($(srctree),)
srctree := $(patsubst %/,%,$(dir $(CURDIR)))
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 36a65cecada3..c4d6b90b1134 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -89,6 +89,46 @@ s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
return phys_to_virt(addend);
}
+static void scan_for_insn(struct section *sec, unsigned long offset,
+ unsigned long *insn_off, unsigned int *insn_len)
+{
+ unsigned long o = 0;
+ struct insn insn;
+
+ while (1) {
+
+ insn_decode(&insn, sec->data->d_buf + o, sec_size(sec) - o,
+ INSN_MODE_64);
+
+ if (o + insn.length > offset) {
+ *insn_off = o;
+ *insn_len = insn.length;
+ return;
+ }
+
+ o += insn.length;
+ }
+}
+
+u64 arch_adjusted_addend(struct reloc *reloc)
+{
+ unsigned int type = reloc_type(reloc);
+ s64 addend = reloc_addend(reloc);
+ unsigned long insn_off;
+ unsigned int insn_len;
+
+ if (type == R_X86_64_PLT32)
+ return addend + 4;
+
+ if (type != R_X86_64_PC32 || !is_text_sec(reloc->sec->base))
+ return addend;
+
+ scan_for_insn(reloc->sec->base, reloc_offset(reloc),
+ &insn_off, &insn_len);
+
+ return addend + insn_off + insn_len - reloc_offset(reloc);
+}
+
unsigned long arch_jump_destination(struct instruction *insn)
{
return insn->offset + insn->len + insn->immediate;
diff --git a/tools/objtool/builtin-klp.c b/tools/objtool/builtin-klp.c
new file mode 100644
index 000000000000..9b13dd1182af
--- /dev/null
+++ b/tools/objtool/builtin-klp.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <subcmd/parse-options.h>
+#include <string.h>
+#include <stdlib.h>
+#include <objtool/builtin.h>
+#include <objtool/objtool.h>
+#include <objtool/klp.h>
+
+struct subcmd {
+ const char *name;
+ const char *description;
+ int (*fn)(int, const char **);
+};
+
+static struct subcmd subcmds[] = {
+ { "diff", "Generate binary diff of two object files", cmd_klp_diff, },
+};
+
+static void cmd_klp_usage(void)
+{
+ fprintf(stderr, "usage: objtool klp <subcommand> [<options>]\n\n");
+ fprintf(stderr, "Subcommands:\n");
+
+ for (int i = 0; i < ARRAY_SIZE(subcmds); i++) {
+ struct subcmd *cmd = &subcmds[i];
+
+ fprintf(stderr, " %s\t%s\n", cmd->name, cmd->description);
+ }
+
+ exit(1);
+}
+
+int cmd_klp(int argc, const char **argv)
+{
+ argc--;
+ argv++;
+
+ if (!argc)
+ cmd_klp_usage();
+
+ if (argc) {
+ for (int i = 0; i < ARRAY_SIZE(subcmds); i++) {
+ struct subcmd *cmd = &subcmds[i];
+
+ if (!strcmp(cmd->name, argv[0]))
+ return cmd->fn(argc, argv);
+ }
+ }
+
+ cmd_klp_usage();
+ return 0;
+}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 7e492945e5e5..9d1f545279a6 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -186,20 +186,6 @@ static bool is_sibling_call(struct instruction *insn)
return (is_static_jump(insn) && insn_call_dest(insn));
}
-/*
- * Checks if a string ends with another.
- */
-static bool str_ends_with(const char *s, const char *sub)
-{
- const int slen = strlen(s);
- const int sublen = strlen(sub);
-
- if (sublen > slen)
- return 0;
-
- return !memcmp(s + slen - sublen, sub, sublen);
-}
-
/*
* Checks if a function is a Rust "noreturn" one.
*/
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d2f418a34881..16c8d36afe4e 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -288,6 +288,18 @@ struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
return NULL;
}
+struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *name)
+{
+ struct symbol *sym;
+
+ elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
+ if (!strcmp(sym->name, name) && !is_local_sym(sym))
+ return sym;
+ }
+
+ return NULL;
+}
+
struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
unsigned long offset, unsigned int len)
{
@@ -475,6 +487,8 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
else
entry = &sym->sec->symbol_list;
list_add(&sym->list, entry);
+
+ list_add_tail(&sym->global_list, &elf->symbols);
elf_hash_add(symbol, &sym->hash, sym->idx);
elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
@@ -528,6 +542,9 @@ static int read_symbols(struct elf *elf)
ERROR_GLIBC("calloc");
return -1;
}
+
+ INIT_LIST_HEAD(&elf->symbols);
+
for (i = 0; i < symbols_nr; i++) {
sym = &elf->symbol_data[i];
@@ -636,7 +653,7 @@ static int mark_group_syms(struct elf *elf)
return -1;
}
- list_for_each_entry(sec, &elf->sections, list) {
+ for_each_sec(elf, sec) {
if (sec->sh.sh_type == SHT_GROUP &&
sec->sh.sh_link == symtab->idx) {
sym = find_symbol_by_index(elf, sec->sh.sh_info);
@@ -1219,6 +1236,8 @@ struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)
return NULL;
}
+ INIT_LIST_HEAD(&elf->symbols);
+
if (!elf_alloc_hash(section, 1000) ||
!elf_alloc_hash(section_name, 1000) ||
!elf_alloc_hash(symbol, 10000) ||
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index 07729a240159..03c86caec4d6 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -84,6 +84,7 @@ bool arch_callee_saved_reg(unsigned char reg);
unsigned long arch_jump_destination(struct instruction *insn);
s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc);
+u64 arch_adjusted_addend(struct reloc *reloc);
const char *arch_nop_insn(int len);
const char *arch_ret_insn(int len);
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 92bc7089cfc1..e60438577000 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -52,4 +52,6 @@ int objtool_run(int argc, const char **argv);
int make_backup(void);
+int cmd_klp(int argc, const char **argv);
+
#endif /* _BUILTIN_H */
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 4cfd09e66cb5..903cbcb84e6b 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -17,6 +17,7 @@
#include <objtool/checksum_types.h>
#include <arch/elf.h>
+#define SEC_NAME_LEN 1024
#define SYM_NAME_LEN 512
#ifdef LIBELF_USE_DEPRECATED
@@ -50,10 +51,12 @@ struct section {
bool _changed, text, rodata, noinstr, init, truncate;
struct reloc *relocs;
unsigned long nr_alloc_relocs;
+ struct section *twin;
};
struct symbol {
struct list_head list;
+ struct list_head global_list;
struct rb_node node;
struct elf_hash_node hash;
struct elf_hash_node name_hash;
@@ -79,10 +82,13 @@ struct symbol {
u8 cold : 1;
u8 prefix : 1;
u8 debug_checksum : 1;
+ u8 changed : 1;
+ u8 included : 1;
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;
struct checksum csum;
+ struct symbol *twin, *clone;
};
struct reloc {
@@ -100,6 +106,7 @@ struct elf {
const char *name, *tmp_name;
unsigned int num_files;
struct list_head sections;
+ struct list_head symbols;
unsigned long num_relocs;
int symbol_bits;
@@ -175,6 +182,7 @@ struct section *find_section_by_name(const struct elf *elf, const char *name);
struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
+struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *name);
struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
int find_symbol_hole_containing(const struct section *sec, unsigned long offset);
struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
@@ -435,22 +443,44 @@ static inline void set_sym_next_reloc(struct reloc *reloc, struct reloc *next)
#define sec_for_each_sym(sec, sym) \
list_for_each_entry(sym, &sec->symbol_list, list)
+#define sec_prev_sym(sym) \
+ sym->sec && sym->list.prev != &sym->sec->symbol_list ? \
+ list_prev_entry(sym, list) : NULL
+
#define for_each_sym(elf, sym) \
- for (struct section *__sec, *__fake = (struct section *)1; \
- __fake; __fake = NULL) \
- for_each_sec(elf, __sec) \
- sec_for_each_sym(__sec, sym)
+ list_for_each_entry(sym, &elf->symbols, global_list)
+
+#define for_each_sym_continue(elf, sym) \
+ list_for_each_entry_continue(sym, &elf->symbols, global_list)
+
+#define rsec_next_reloc(rsec, reloc) \
+ reloc_idx(reloc) < sec_num_entries(rsec) - 1 ? reloc + 1 : NULL
#define for_each_reloc(rsec, reloc) \
- for (int __i = 0, __fake = 1; __fake; __fake = 0) \
- for (reloc = rsec->relocs; \
- __i < sec_num_entries(rsec); \
- __i++, reloc++)
+ for (reloc = rsec->relocs; reloc; reloc = rsec_next_reloc(rsec, reloc))
#define for_each_reloc_from(rsec, reloc) \
- for (int __i = reloc_idx(reloc); \
- __i < sec_num_entries(rsec); \
- __i++, reloc++)
+ for (; reloc; reloc = rsec_next_reloc(rsec, reloc))
+
+#define sym_for_each_reloc(elf, sym, reloc) \
+ for (reloc = find_reloc_by_dest_range(elf, sym->sec, \
+ sym->offset, sym->len); \
+ reloc && reloc_offset(reloc) < sym->offset + sym->len; \
+ reloc = rsec_next_reloc(sym->sec->rsec, reloc))
+
+static inline struct symbol *get_func_prefix(struct symbol *func)
+{
+ struct symbol *prev;
+
+ if (!is_func_sym(func))
+ return NULL;
+
+ prev = sec_prev_sym(func);
+ if (prev && is_prefix_func(prev))
+ return prev;
+
+ return NULL;
+}
#define OFFSET_STRIDE_BITS 4
#define OFFSET_STRIDE (1UL << OFFSET_STRIDE_BITS)
diff --git a/tools/objtool/include/objtool/klp.h b/tools/objtool/include/objtool/klp.h
new file mode 100644
index 000000000000..07928fac059b
--- /dev/null
+++ b/tools/objtool/include/objtool/klp.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _OBJTOOL_KLP_H
+#define _OBJTOOL_KLP_H
+
+/*
+ * __klp_objects and __klp_funcs are created by klp diff and used by the patch
+ * module init code to build the klp_patch, klp_object and klp_func structs
+ * needed by the livepatch API.
+ */
+#define KLP_OBJECTS_SEC "__klp_objects"
+#define KLP_FUNCS_SEC "__klp_funcs"
+
+/*
+ * __klp_relocs is an intermediate section which are created by klp diff and
+ * converted into KLP symbols/relas by "objtool klp post-link". This is needed
+ * to work around the linker, which doesn't preserve SHN_LIVEPATCH or
+ * SHF_RELA_LIVEPATCH, nor does it support having two RELA sections for a
+ * single PROGBITS section.
+ */
+#define KLP_RELOCS_SEC "__klp_relocs"
+#define KLP_STRINGS_SEC ".rodata.klp.str1.1"
+
+struct klp_reloc {
+ void *offset;
+ void *sym;
+ u32 type;
+};
+
+int cmd_klp_diff(int argc, const char **argv);
+
+#endif /* _OBJTOOL_KLP_H */
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index 90c591b5bd68..37e9fe4492d6 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -41,6 +41,8 @@ struct objtool_file {
struct pv_state *pv_ops;
};
+char *top_level_dir(const char *file);
+
struct objtool_file *objtool_open_read(const char *_objname);
int objtool_pv_add(struct objtool_file *file, int idx, struct symbol *func);
diff --git a/tools/objtool/include/objtool/util.h b/tools/objtool/include/objtool/util.h
new file mode 100644
index 000000000000..a0180b312f73
--- /dev/null
+++ b/tools/objtool/include/objtool/util.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _UTIL_H
+#define _UTIL_H
+
+#include <objtool/warn.h>
+
+#define snprintf_check(str, size, format, args...) \
+({ \
+ int __ret = snprintf(str, size, format, args); \
+ if (__ret < 0) \
+ ERROR_GLIBC("snprintf"); \
+ else if (__ret >= size) \
+ ERROR("snprintf() failed for '" format "'", args); \
+ else \
+ __ret = 0; \
+ __ret; \
+})
+
+#endif /* _UTIL_H */
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
new file mode 100644
index 000000000000..85c6a480ecdb
--- /dev/null
+++ b/tools/objtool/klp-diff.c
@@ -0,0 +1,1600 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#define _GNU_SOURCE /* memmem() */
+#include <subcmd/parse-options.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#include <objtool/objtool.h>
+#include <objtool/warn.h>
+#include <objtool/arch.h>
+#include <objtool/klp.h>
+#include <objtool/util.h>
+#include <arch/special.h>
+
+#include <linux/livepatch_external.h>
+#include <linux/stringify.h>
+#include <linux/string.h>
+#include <linux/jhash.h>
+
+#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+
+struct elfs {
+ struct elf *orig, *patched, *out;
+ const char *modname;
+};
+
+struct export {
+ struct hlist_node hash;
+ char *mod, *sym;
+};
+
+static const char * const klp_diff_usage[] = {
+ "objtool klp diff [<options>] <in1.o> <in2.o> <out.o>",
+ NULL,
+};
+
+static const struct option klp_diff_options[] = {
+ OPT_END(),
+};
+
+static DEFINE_HASHTABLE(exports, 15);
+
+static inline u32 str_hash(const char *str)
+{
+ return jhash(str, strlen(str), 0);
+}
+
+static int read_exports(void)
+{
+ const char *symvers = "Module.symvers";
+ char line[1024], *path = NULL;
+ unsigned int line_num = 1;
+ FILE *file;
+
+ file = fopen(symvers, "r");
+ if (!file) {
+ path = top_level_dir(symvers);
+ if (!path) {
+ ERROR("can't open '%s', \"objtool diff\" should be run from the kernel tree", symvers);
+ return -1;
+ }
+
+ file = fopen(path, "r");
+ if (!file) {
+ ERROR_GLIBC("fopen");
+ return -1;
+ }
+ }
+
+ while (fgets(line, 1024, file)) {
+ char *sym, *mod, *type;
+ struct export *export;
+
+ sym = strchr(line, '\t');
+ if (!sym) {
+ ERROR("malformed Module.symvers (sym) at line %d", line_num);
+ return -1;
+ }
+
+ *sym++ = '\0';
+
+ mod = strchr(sym, '\t');
+ if (!mod) {
+ ERROR("malformed Module.symvers (mod) at line %d", line_num);
+ return -1;
+ }
+
+ *mod++ = '\0';
+
+ type = strchr(mod, '\t');
+ if (!type) {
+ ERROR("malformed Module.symvers (type) at line %d", line_num);
+ return -1;
+ }
+
+ *type++ = '\0';
+
+ if (*sym == '\0' || *mod == '\0') {
+ ERROR("malformed Module.symvers at line %d", line_num);
+ return -1;
+ }
+
+ export = calloc(1, sizeof(*export));
+ if (!export) {
+ ERROR_GLIBC("calloc");
+ return -1;
+ }
+
+ export->mod = strdup(mod);
+ if (!export->mod) {
+ ERROR_GLIBC("strdup");
+ return -1;
+ }
+
+ export->sym = strdup(sym);
+ if (!export->sym) {
+ ERROR_GLIBC("strdup");
+ return -1;
+ }
+
+ hash_add(exports, &export->hash, str_hash(sym));
+ }
+
+ free(path);
+ fclose(file);
+
+ return 0;
+}
+
+static int read_sym_checksums(struct elf *elf)
+{
+ struct section *sec;
+
+ sec = find_section_by_name(elf, SYM_CHECKSUM_SEC);
+ if (!sec) {
+ ERROR("'%s' missing " SYM_CHECKSUM_SEC " section, file not processed by 'objtool --checksum'?",
+ elf->name);
+ return -1;
+ }
+
+ if (!sec->rsec) {
+ ERROR("missing reloc section for " SYM_CHECKSUM_SEC);
+ return -1;
+ }
+
+ if (sec_size(sec) % sizeof(struct sym_checksum)) {
+ ERROR("struct sym_checksum size mismatch");
+ return -1;
+ }
+
+ for (int i = 0; i < sec_size(sec) / sizeof(struct sym_checksum); i++) {
+ struct sym_checksum *sym_checksum;
+ struct reloc *reloc;
+ struct symbol *sym;
+
+ sym_checksum = (struct sym_checksum *)sec->data->d_buf + i;
+
+ reloc = find_reloc_by_dest(elf, sec, i * sizeof(*sym_checksum));
+ if (!reloc) {
+ ERROR("can't find reloc for sym_checksum[%d]", i);
+ return -1;
+ }
+
+ sym = reloc->sym;
+
+ if (is_sec_sym(sym)) {
+ ERROR("not sure how to handle section %s", sym->name);
+ return -1;
+ }
+
+ if (is_func_sym(sym))
+ sym->csum.checksum = sym_checksum->checksum;
+ }
+
+ return 0;
+}
+
+static struct symbol *first_file_symbol(struct elf *elf)
+{
+ struct symbol *sym;
+
+ for_each_sym(elf, sym) {
+ if (is_file_sym(sym))
+ return sym;
+ }
+
+ return NULL;
+}
+
+static struct symbol *next_file_symbol(struct elf *elf, struct symbol *sym)
+{
+ for_each_sym_continue(elf, sym) {
+ if (is_file_sym(sym))
+ return sym;
+ }
+
+ return NULL;
+}
+
+/*
+ * Certain static local variables should never be correlated. They will be
+ * used in place rather than referencing the originals.
+ */
+static bool is_uncorrelated_static_local(struct symbol *sym)
+{
+ static const char * const vars[] = {
+ "__key.",
+ "__warned.",
+ "__already_done.",
+ "__func__.",
+ "_rs.",
+ "descriptor.",
+ "CSWTCH.",
+ };
+
+ if (!is_object_sym(sym) || !is_local_sym(sym))
+ return false;
+
+ if (!strcmp(sym->sec->name, ".data.once"))
+ return true;
+
+ for (int i = 0; i < ARRAY_SIZE(vars); i++) {
+ if (strstarts(sym->name, vars[i]))
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Clang emits several useless .Ltmp_* code labels.
+ */
+static bool is_clang_tmp_label(struct symbol *sym)
+{
+ return sym->type == STT_NOTYPE &&
+ is_text_sec(sym->sec) &&
+ strstarts(sym->name, ".Ltmp") &&
+ isdigit(sym->name[5]);
+}
+
+static bool is_special_section(struct section *sec)
+{
+ static const char * const specials[] = {
+ ".altinstructions",
+ ".smp_locks",
+ "__bug_table",
+ "__ex_table",
+ "__jump_table",
+ "__mcount_loc",
+
+ /*
+ * Extract .static_call_sites here to inherit non-module
+ * preferential treatment. The later static call processing
+ * during klp module build will be skipped when it sees this
+ * section already exists.
+ */
+ ".static_call_sites",
+ };
+
+ static const char * const non_special_discards[] = {
+ ".discard.addressable",
+ SYM_CHECKSUM_SEC,
+ };
+
+ if (is_text_sec(sec))
+ return false;
+
+ for (int i = 0; i < ARRAY_SIZE(specials); i++) {
+ if (!strcmp(sec->name, specials[i]))
+ return true;
+ }
+
+ /* Most .discard data sections are special */
+ for (int i = 0; i < ARRAY_SIZE(non_special_discards); i++) {
+ if (!strcmp(sec->name, non_special_discards[i]))
+ return false;
+ }
+
+ return strstarts(sec->name, ".discard.");
+}
+
+/*
+ * These sections are referenced by special sections but aren't considered
+ * special sections themselves.
+ */
+static bool is_special_section_aux(struct section *sec)
+{
+ static const char * const specials_aux[] = {
+ ".altinstr_replacement",
+ ".altinstr_aux",
+ };
+
+ for (int i = 0; i < ARRAY_SIZE(specials_aux); i++) {
+ if (!strcmp(sec->name, specials_aux[i]))
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * These symbols should never be correlated, so their local patched versions
+ * are used instead of linking to the originals.
+ */
+static bool dont_correlate(struct symbol *sym)
+{
+ return is_file_sym(sym) ||
+ is_null_sym(sym) ||
+ is_sec_sym(sym) ||
+ is_prefix_func(sym) ||
+ is_uncorrelated_static_local(sym) ||
+ is_clang_tmp_label(sym) ||
+ is_string_sec(sym->sec) ||
+ is_special_section(sym->sec) ||
+ is_special_section_aux(sym->sec) ||
+ strstarts(sym->name, "__initcall__");
+}
+
+/*
+ * For each symbol in the original kernel, find its corresponding "twin" in the
+ * patched kernel.
+ */
+static int correlate_symbols(struct elfs *e)
+{
+ struct symbol *file1_sym, *file2_sym;
+ struct symbol *sym1, *sym2;
+
+ /* Correlate locals */
+ for (file1_sym = first_file_symbol(e->orig),
+ file2_sym = first_file_symbol(e->patched); ;
+ file1_sym = next_file_symbol(e->orig, file1_sym),
+ file2_sym = next_file_symbol(e->patched, file2_sym)) {
+
+ if (!file1_sym && file2_sym) {
+ ERROR("FILE symbol mismatch: NULL != %s", file2_sym->name);
+ return -1;
+ }
+
+ if (file1_sym && !file2_sym) {
+ ERROR("FILE symbol mismatch: %s != NULL", file1_sym->name);
+ return -1;
+ }
+
+ if (!file1_sym)
+ break;
+
+ if (strcmp(file1_sym->name, file2_sym->name)) {
+ ERROR("FILE symbol mismatch: %s != %s", file1_sym->name, file2_sym->name);
+ return -1;
+ }
+
+ file1_sym->twin = file2_sym;
+ file2_sym->twin = file1_sym;
+
+ sym1 = file1_sym;
+
+ for_each_sym_continue(e->orig, sym1) {
+ if (is_file_sym(sym1) || !is_local_sym(sym1))
+ break;
+
+ if (dont_correlate(sym1))
+ continue;
+
+ sym2 = file2_sym;
+ for_each_sym_continue(e->patched, sym2) {
+ if (is_file_sym(sym2) || !is_local_sym(sym2))
+ break;
+
+ if (sym2->twin || dont_correlate(sym2))
+ continue;
+
+ if (strcmp(sym1->demangled_name, sym2->demangled_name))
+ continue;
+
+ sym1->twin = sym2;
+ sym2->twin = sym1;
+ break;
+ }
+ }
+ }
+
+ /* Correlate globals */
+ for_each_sym(e->orig, sym1) {
+ if (sym1->bind == STB_LOCAL)
+ continue;
+
+ sym2 = find_global_symbol_by_name(e->patched, sym1->name);
+
+ if (sym2 && !sym2->twin && !strcmp(sym1->name, sym2->name)) {
+ sym1->twin = sym2;
+ sym2->twin = sym1;
+ }
+ }
+
+ for_each_sym(e->orig, sym1) {
+ if (sym1->twin || dont_correlate(sym1))
+ continue;
+ WARN("no correlation: %s", sym1->name);
+ }
+
+ return 0;
+}
+
+/* "sympos" is used by livepatch to disambiguate duplicate symbol names */
+static unsigned long find_sympos(struct elf *elf, struct symbol *sym)
+{
+ bool vmlinux = str_ends_with(objname, "vmlinux.o");
+ unsigned long sympos = 0, nr_matches = 0;
+ bool has_dup = false;
+ struct symbol *s;
+
+ if (sym->bind != STB_LOCAL)
+ return 0;
+
+ if (vmlinux && sym->type == STT_FUNC) {
+ /*
+ * HACK: Unfortunately, symbol ordering can differ between
+ * vmlinux.o and vmlinux due to the linker script emitting
+ * .text.unlikely* before .text*. Count .text.unlikely* first.
+ *
+ * TODO: Disambiguate symbols more reliably (checksums?)
+ */
+ for_each_sym(elf, s) {
+ if (strstarts(s->sec->name, ".text.unlikely") &&
+ !strcmp(s->name, sym->name)) {
+ nr_matches++;
+ if (s == sym)
+ sympos = nr_matches;
+ else
+ has_dup = true;
+ }
+ }
+ for_each_sym(elf, s) {
+ if (!strstarts(s->sec->name, ".text.unlikely") &&
+ !strcmp(s->name, sym->name)) {
+ nr_matches++;
+ if (s == sym)
+ sympos = nr_matches;
+ else
+ has_dup = true;
+ }
+ }
+ } else {
+ for_each_sym(elf, s) {
+ if (!strcmp(s->name, sym->name)) {
+ nr_matches++;
+ if (s == sym)
+ sympos = nr_matches;
+ else
+ has_dup = true;
+ }
+ }
+ }
+
+ if (!sympos) {
+ ERROR("can't find sympos for %s", sym->name);
+ return ULONG_MAX;
+ }
+
+ return has_dup ? sympos : 0;
+}
+
+static int clone_sym_relocs(struct elfs *e, struct symbol *patched_sym);
+
+static struct symbol *__clone_symbol(struct elf *elf, struct symbol *patched_sym,
+ bool data_too)
+{
+ struct section *out_sec = NULL;
+ unsigned long offset = 0;
+ struct symbol *out_sym;
+
+ if (data_too && !is_undef_sym(patched_sym)) {
+ struct section *patched_sec = patched_sym->sec;
+
+ out_sec = find_section_by_name(elf, patched_sec->name);
+ if (!out_sec) {
+ out_sec = elf_create_section(elf, patched_sec->name, 0,
+ patched_sec->sh.sh_entsize,
+ patched_sec->sh.sh_type,
+ patched_sec->sh.sh_addralign,
+ patched_sec->sh.sh_flags);
+ if (!out_sec)
+ return NULL;
+ }
+
+ if (is_string_sec(patched_sym->sec)) {
+ out_sym = elf_create_section_symbol(elf, out_sec);
+ if (!out_sym)
+ return NULL;
+
+ goto sym_created;
+ }
+
+ if (!is_sec_sym(patched_sym))
+ offset = sec_size(out_sec);
+
+ if (patched_sym->len || is_sec_sym(patched_sym)) {
+ void *data = NULL;
+ size_t size;
+
+ /* bss doesn't have data */
+ if (patched_sym->sec->data->d_buf)
+ data = patched_sym->sec->data->d_buf + patched_sym->offset;
+
+ if (is_sec_sym(patched_sym))
+ size = sec_size(patched_sym->sec);
+ else
+ size = patched_sym->len;
+
+ if (!elf_add_data(elf, out_sec, data, size))
+ return NULL;
+ }
+ }
+
+ out_sym = elf_create_symbol(elf, patched_sym->name, out_sec,
+ patched_sym->bind, patched_sym->type,
+ offset, patched_sym->len);
+ if (!out_sym)
+ return NULL;
+
+sym_created:
+ patched_sym->clone = out_sym;
+ out_sym->clone = patched_sym;
+
+ return out_sym;
+}
+
+/*
+ * Copy a symbol to the output object, optionally including its data and
+ * relocations.
+ */
+static struct symbol *clone_symbol(struct elfs *e, struct symbol *patched_sym,
+ bool data_too)
+{
+ struct symbol *pfx;
+
+ if (patched_sym->clone)
+ return patched_sym->clone;
+
+ /* Make sure the prefix gets cloned first */
+ if (is_func_sym(patched_sym) && data_too) {
+ pfx = get_func_prefix(patched_sym);
+ if (pfx)
+ clone_symbol(e, pfx, true);
+ }
+
+ if (!__clone_symbol(e->out, patched_sym, data_too))
+ return NULL;
+
+ if (data_too && clone_sym_relocs(e, patched_sym))
+ return NULL;
+
+ return patched_sym->clone;
+}
+
+static void mark_included_function(struct symbol *func)
+{
+ struct symbol *pfx;
+
+ func->included = 1;
+
+ /* Include prefix function */
+ pfx = get_func_prefix(func);
+ if (pfx)
+ pfx->included = 1;
+
+ /* Make sure .cold parent+child always stay together */
+ if (func->cfunc && func->cfunc != func)
+ func->cfunc->included = 1;
+ if (func->pfunc && func->pfunc != func)
+ func->pfunc->included = 1;
+}
+
+/*
+ * Copy all changed functions (and their dependencies) from the patched object
+ * to the output object.
+ */
+static int mark_changed_functions(struct elfs *e)
+{
+ struct symbol *sym_orig, *patched_sym;
+ bool changed = false;
+
+ /* Find changed functions */
+ for_each_sym(e->orig, sym_orig) {
+ if (!is_func_sym(sym_orig) || is_prefix_func(sym_orig))
+ continue;
+
+ patched_sym = sym_orig->twin;
+ if (!patched_sym)
+ continue;
+
+ if (sym_orig->csum.checksum != patched_sym->csum.checksum) {
+ patched_sym->changed = 1;
+ mark_included_function(patched_sym);
+ changed = true;
+ }
+ }
+
+ /* Find added functions and print them */
+ for_each_sym(e->patched, patched_sym) {
+ if (!is_func_sym(patched_sym) || is_prefix_func(patched_sym))
+ continue;
+
+ if (!patched_sym->twin) {
+ printf("%s: new function: %s\n", objname, patched_sym->name);
+ mark_included_function(patched_sym);
+ changed = true;
+ }
+ }
+
+ /* Print changed functions */
+ for_each_sym(e->patched, patched_sym) {
+ if (patched_sym->changed)
+ printf("%s: changed function: %s\n", objname, patched_sym->name);
+ }
+
+ return !changed ? -1 : 0;
+}
+
+static int clone_included_functions(struct elfs *e)
+{
+ struct symbol *patched_sym;
+
+ for_each_sym(e->patched, patched_sym) {
+ if (patched_sym->included) {
+ if (!clone_symbol(e, patched_sym, true))
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Determine whether a relocation should reference the section rather than the
+ * underlying symbol.
+ */
+static bool section_reference_needed(struct section *sec)
+{
+ /*
+ * String symbols are zero-length and uncorrelated. It's easier to
+ * deal with them as section symbols.
+ */
+ if (is_string_sec(sec))
+ return true;
+
+ /*
+ * .rodata has mostly anonymous data so there's no way to determine the
+ * length of a needed reference. just copy the whole section if needed.
+ */
+ if (strstarts(sec->name, ".rodata"))
+ return true;
+
+ /* UBSAN anonymous data */
+ if (strstarts(sec->name, ".data..Lubsan") || /* GCC */
+ strstarts(sec->name, ".data..L__unnamed_")) /* Clang */
+ return true;
+
+ return false;
+}
+
+static bool is_reloc_allowed(struct reloc *reloc)
+{
+ return section_reference_needed(reloc->sym->sec) == is_sec_sym(reloc->sym);
+}
+
+static struct export *find_export(struct symbol *sym)
+{
+ struct export *export;
+
+ hash_for_each_possible(exports, export, hash, str_hash(sym->name)) {
+ if (!strcmp(export->sym, sym->name))
+ return export;
+ }
+
+ return NULL;
+}
+
+static const char *__find_modname(struct elfs *e)
+{
+ struct section *sec;
+ char *name;
+
+ sec = find_section_by_name(e->orig, ".modinfo");
+ if (!sec) {
+ ERROR("missing .modinfo section");
+ return NULL;
+ }
+
+ name = memmem(sec->data->d_buf, sec_size(sec), "\0name=", 6);
+ if (name)
+ return name + 6;
+
+ name = strdup(e->orig->name);
+ if (!name) {
+ ERROR_GLIBC("strdup");
+ return NULL;
+ }
+
+ for (char *c = name; *c; c++) {
+ if (*c == '/')
+ name = c + 1;
+ else if (*c == '-')
+ *c = '_';
+ else if (*c == '.') {
+ *c = '\0';
+ break;
+ }
+ }
+
+ return name;
+}
+
+/* Get the object's module name as defined by the kernel (and klp_object) */
+static const char *find_modname(struct elfs *e)
+{
+ const char *modname;
+
+ if (e->modname)
+ return e->modname;
+
+ modname = __find_modname(e);
+ e->modname = modname;
+ return modname;
+}
+
+/*
+ * Copying a function from its native compiled environment to a kernel module
+ * removes its natural access to local functions/variables and unexported
+ * globals. References to such symbols need to be converted to KLP relocs so
+ * the kernel arch relocation code knows to apply them and where to find the
+ * symbols. Particularly, duplicate static symbols need to be disambiguated.
+ */
+static bool klp_reloc_needed(struct reloc *patched_reloc)
+{
+ struct symbol *patched_sym = patched_reloc->sym;
+ struct export *export;
+
+ /* no external symbol to reference */
+ if (dont_correlate(patched_sym))
+ return false;
+
+ /* For included functions, a regular reloc will do. */
+ if (patched_sym->included)
+ return false;
+
+ /*
+ * If exported by a module, it has to be a klp reloc. Thanks to the
+ * clusterfunk that is late module patching, the patch module is
+ * allowed to be loaded before any modules it depends on.
+ *
+ * If exported by vmlinux, a normal reloc will do.
+ */
+ export = find_export(patched_sym);
+ if (export)
+ return strcmp(export->mod, "vmlinux");
+
+ if (!patched_sym->twin) {
+ /*
+ * Presumably the symbol and its reference were added by the
+ * patch. The symbol could be defined in this .o or in another
+ * .o in the patch module.
+ *
+ * This check needs to be *after* the export check due to the
+ * possibility of the patch adding a new UNDEF reference to an
+ * exported symbol.
+ */
+ return false;
+ }
+
+ /* Unexported symbol which lives in the original vmlinux or module. */
+ return true;
+}
+
+static int convert_reloc_sym_to_secsym(struct elf *elf, struct reloc *reloc)
+{
+ struct symbol *sym = reloc->sym;
+ struct section *sec = sym->sec;
+
+ if (!sec->sym && !elf_create_section_symbol(elf, sec))
+ return -1;
+
+ reloc->sym = sec->sym;
+ set_reloc_sym(elf, reloc, sym->idx);
+ set_reloc_addend(elf, reloc, sym->offset + reloc_addend(reloc));
+ return 0;
+}
+
+static int convert_reloc_secsym_to_sym(struct elf *elf, struct reloc *reloc)
+{
+ struct symbol *sym = reloc->sym;
+ struct section *sec = sym->sec;
+
+ /* If the symbol has a dedicated section, it's easy to find */
+ sym = find_symbol_by_offset(sec, 0);
+ if (sym && sym->len == sec_size(sec))
+ goto found_sym;
+
+ /* No dedicated section; find the symbol manually */
+ sym = find_symbol_containing(sec, arch_adjusted_addend(reloc));
+ if (!sym) {
+ /*
+ * This can happen for special section references to weak code
+ * whose symbol has been stripped by the linker.
+ */
+ return -1;
+ }
+
+found_sym:
+ reloc->sym = sym;
+ set_reloc_sym(elf, reloc, sym->idx);
+ set_reloc_addend(elf, reloc, reloc_addend(reloc) - sym->offset);
+ return 0;
+}
+
+/*
+ * Convert a relocation symbol reference to the needed format: either a section
+ * symbol or the underlying symbol itself.
+ */
+static int convert_reloc_sym(struct elf *elf, struct reloc *reloc)
+{
+ if (is_reloc_allowed(reloc))
+ return 0;
+
+ if (section_reference_needed(reloc->sym->sec))
+ return convert_reloc_sym_to_secsym(elf, reloc);
+ else
+ return convert_reloc_secsym_to_sym(elf, reloc);
+}
+
+/*
+ * Convert a regular relocation to a klp relocation (sort of).
+ */
+static int clone_reloc_klp(struct elfs *e, struct reloc *patched_reloc,
+ struct section *sec, unsigned long offset,
+ struct export *export)
+{
+ struct symbol *patched_sym = patched_reloc->sym;
+ s64 addend = reloc_addend(patched_reloc);
+ const char *sym_modname, *sym_orig_name;
+ static struct section *klp_relocs;
+ struct symbol *sym, *klp_sym;
+ unsigned long klp_reloc_off;
+ char sym_name[SYM_NAME_LEN];
+ struct klp_reloc klp_reloc;
+ unsigned long sympos;
+
+ if (!patched_sym->twin) {
+ ERROR("unexpected klp reloc for new symbol %s", patched_sym->name);
+ return -1;
+ }
+
+ /*
+ * Keep the original reloc intact for now to avoid breaking objtool run
+ * which relies on proper relocations for many of its features. This
+ * will be disabled later by "objtool klp post-link".
+ *
+ * Convert it to UNDEF (and WEAK to avoid modpost warnings).
+ */
+
+ sym = patched_sym->clone;
+ if (!sym) {
+ /* STB_WEAK: avoid modpost undefined symbol warnings */
+ sym = elf_create_symbol(e->out, patched_sym->name, NULL,
+ STB_WEAK, patched_sym->type, 0, 0);
+ if (!sym)
+ return -1;
+
+ patched_sym->clone = sym;
+ sym->clone = patched_sym;
+ }
+
+ if (!elf_create_reloc(e->out, sec, offset, sym, addend, reloc_type(patched_reloc)))
+ return -1;
+
+ /*
+ * Create the KLP symbol.
+ */
+
+ if (export) {
+ sym_modname = export->mod;
+ sym_orig_name = export->sym;
+ sympos = 0;
+ } else {
+ sym_modname = find_modname(e);
+ if (!sym_modname)
+ return -1;
+
+ sym_orig_name = patched_sym->twin->name;
+ sympos = find_sympos(e->orig, patched_sym->twin);
+ if (sympos == ULONG_MAX)
+ return -1;
+ }
+
+ /* symbol format: .klp.sym.modname.sym_name,sympos */
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_SYM_PREFIX "%s.%s,%ld",
+ sym_modname, sym_orig_name, sympos))
+ return -1;
+
+ klp_sym = find_symbol_by_name(e->out, sym_name);
+ if (!klp_sym) {
+ /* STB_WEAK: avoid modpost undefined symbol warnings */
+ klp_sym = elf_create_symbol(e->out, sym_name, NULL,
+ STB_WEAK, patched_sym->type, 0, 0);
+ if (!klp_sym)
+ return -1;
+ }
+
+ /*
+ * Create the __klp_relocs entry. This will be converted to an actual
+ * KLP rela by "objtool klp post-link".
+ *
+ * This intermediate step is necessary to prevent corruption by the
+ * linker, which doesn't know how to properly handle two rela sections
+ * applying to the same base section.
+ */
+
+ if (!klp_relocs) {
+ klp_relocs = elf_create_section(e->out, KLP_RELOCS_SEC, 0,
+ 0, SHT_PROGBITS, 8, SHF_ALLOC);
+ if (!klp_relocs)
+ return -1;
+ }
+
+ klp_reloc_off = sec_size(klp_relocs);
+ memset(&klp_reloc, 0, sizeof(klp_reloc));
+
+ klp_reloc.type = reloc_type(patched_reloc);
+ if (!elf_add_data(e->out, klp_relocs, &klp_reloc, sizeof(klp_reloc)))
+ return -1;
+
+ /* klp_reloc.offset */
+ if (!sec->sym && !elf_create_section_symbol(e->out, sec))
+ return -1;
+
+ if (!elf_create_reloc(e->out, klp_relocs,
+ klp_reloc_off + offsetof(struct klp_reloc, offset),
+ sec->sym, offset, R_ABS64))
+ return -1;
+
+ /* klp_reloc.sym */
+ if (!elf_create_reloc(e->out, klp_relocs,
+ klp_reloc_off + offsetof(struct klp_reloc, sym),
+ klp_sym, addend, R_ABS64))
+ return -1;
+
+ return 0;
+}
+
+/* Copy a reloc and its symbol to the output object */
+static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
+ struct section *sec, unsigned long offset)
+{
+ struct symbol *patched_sym = patched_reloc->sym;
+ struct export *export = find_export(patched_sym);
+ long addend = reloc_addend(patched_reloc);
+ struct symbol *out_sym;
+ bool klp;
+
+ if (!is_reloc_allowed(patched_reloc)) {
+ ERROR_FUNC(patched_reloc->sec->base, reloc_offset(patched_reloc),
+ "missing symbol for reference to %s+%ld",
+ patched_sym->name, addend);
+ return -1;
+ }
+
+ klp = klp_reloc_needed(patched_reloc);
+
+ if (klp) {
+ if (clone_reloc_klp(e, patched_reloc, sec, offset, export))
+ return -1;
+
+ return 0;
+ }
+
+ /*
+ * Why !export sets 'data_too':
+ *
+ * Unexported non-klp symbols need to live in the patch module,
+ * otherwise there will be unresolved symbols. Notably, this includes:
+ *
+ * - New functions/data
+ * - String sections
+ * - Special section entries
+ * - Uncorrelated static local variables
+ * - UBSAN sections
+ */
+ out_sym = clone_symbol(e, patched_sym, patched_sym->included || !export);
+ if (!out_sym)
+ return -1;
+
+ /*
+ * For strings, all references use section symbols, thanks to
+ * section_reference_needed(). clone_symbol() has cloned an empty
+ * version of the string section. Now copy the string itself.
+ */
+ if (is_string_sec(patched_sym->sec)) {
+ const char *str = patched_sym->sec->data->d_buf + addend;
+
+ addend = elf_add_string(e->out, out_sym->sec, str);
+ if (addend == -1)
+ return -1;
+ }
+
+ if (!elf_create_reloc(e->out, sec, offset, out_sym, addend,
+ reloc_type(patched_reloc)))
+ return -1;
+
+ return 0;
+}
+
+/* Copy all relocs needed for a symbol's contents */
+static int clone_sym_relocs(struct elfs *e, struct symbol *patched_sym)
+{
+ struct section *patched_rsec = patched_sym->sec->rsec;
+ struct reloc *patched_reloc;
+ unsigned long start, end;
+ struct symbol *out_sym;
+
+ out_sym = patched_sym->clone;
+ if (!out_sym) {
+ ERROR("no clone for %s", patched_sym->name);
+ return -1;
+ }
+
+ if (!patched_rsec)
+ return 0;
+
+ if (!is_sec_sym(patched_sym) && !patched_sym->len)
+ return 0;
+
+ if (is_string_sec(patched_sym->sec))
+ return 0;
+
+ if (is_sec_sym(patched_sym)) {
+ start = 0;
+ end = sec_size(patched_sym->sec);
+ } else {
+ start = patched_sym->offset;
+ end = start + patched_sym->len;
+ }
+
+ for_each_reloc(patched_rsec, patched_reloc) {
+ unsigned long offset;
+
+ if (reloc_offset(patched_reloc) < start ||
+ reloc_offset(patched_reloc) >= end)
+ continue;
+
+ /*
+ * Skip any reloc referencing .altinstr_aux. Its code is
+ * always patched by alternatives. See ALTERNATIVE_TERNARY().
+ */
+ if (patched_reloc->sym->sec &&
+ !strcmp(patched_reloc->sym->sec->name, ".altinstr_aux"))
+ continue;
+
+ if (convert_reloc_sym(e->patched, patched_reloc)) {
+ ERROR_FUNC(patched_rsec->base, reloc_offset(patched_reloc),
+ "failed to convert reloc sym '%s' to its proper format",
+ patched_reloc->sym->name);
+ return -1;
+ }
+
+ offset = out_sym->offset + (reloc_offset(patched_reloc) - patched_sym->offset);
+
+ if (clone_reloc(e, patched_reloc, out_sym->sec, offset))
+ return -1;
+ }
+ return 0;
+
+}
+
+/* Keep a special section entry if it references an included function */
+static bool should_keep_special_sym(struct elf *elf, struct symbol *sym)
+{
+ struct reloc *reloc;
+
+ if (is_sec_sym(sym) || !sym->sec->rsec)
+ return false;
+
+ sym_for_each_reloc(elf, sym, reloc) {
+ if (convert_reloc_sym(elf, reloc))
+ continue;
+
+ if (is_func_sym(reloc->sym) && reloc->sym->included)
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Klp relocations aren't allowed for __jump_table and .static_call_sites if
+ * the referenced symbol lives in a kernel module, because such klp relocs may
+ * be applied after static branch/call init, resulting in code corruption.
+ *
+ * Validate a special section entry to avoid that. Note that an inert
+ * tracepoint is harmless enough, in that case just skip the entry and print a
+ * warning. Otherwise, return an error.
+ *
+ * This is only a temporary limitation which will be fixed when livepatch adds
+ * support for submodules: fully self-contained modules which are embedded in
+ * the top-level livepatch module's data and which can be loaded on demand when
+ * their corresponding to-be-patched module gets loaded. Then klp relocs can
+ * be retired.
+ *
+ * Return:
+ * -1: error: validation failed
+ * 1: warning: tracepoint skipped
+ * 0: success
+ */
+static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym)
+{
+ bool static_branch = !strcmp(sym->sec->name, "__jump_table");
+ bool static_call = !strcmp(sym->sec->name, ".static_call_sites");
+ struct symbol *code_sym = NULL;
+ unsigned long code_offset = 0;
+ struct reloc *reloc;
+ int ret = 0;
+
+ if (!static_branch && !static_call)
+ return 0;
+
+ sym_for_each_reloc(e->patched, sym, reloc) {
+ const char *sym_modname;
+ struct export *export;
+
+ /* Static branch/call keys are always STT_OBJECT */
+ if (reloc->sym->type != STT_OBJECT) {
+
+ /* Save code location which can be printed below */
+ if (reloc->sym->type == STT_FUNC && !code_sym) {
+ code_sym = reloc->sym;
+ code_offset = reloc_addend(reloc);
+ }
+
+ continue;
+ }
+
+ if (!klp_reloc_needed(reloc))
+ continue;
+
+ export = find_export(reloc->sym);
+ if (export) {
+ sym_modname = export->mod;
+ } else {
+ sym_modname = find_modname(e);
+ if (!sym_modname)
+ return -1;
+ }
+
+ /* vmlinux keys are ok */
+ if (!strcmp(sym_modname, "vmlinux"))
+ continue;
+
+ if (static_branch) {
+ if (strstarts(reloc->sym->name, "__tracepoint_")) {
+ WARN("%s: disabling unsupported tracepoint %s",
+ code_sym->name, reloc->sym->name + 13);
+ ret = 1;
+ continue;
+ }
+
+ ERROR("%s+0x%lx: unsupported static branch key %s. Use static_key_enabled() instead",
+ code_sym->name, code_offset, reloc->sym->name);
+ return -1;
+ }
+
+ /* static call */
+ if (strstarts(reloc->sym->name, "__SCK__tp_func_")) {
+ ret = 1;
+ continue;
+ }
+
+ ERROR("%s()+0x%lx: unsupported static call key %s. Use KLP_STATIC_CALL() instead",
+ code_sym->name, code_offset, reloc->sym->name);
+ return -1;
+ }
+
+ return ret;
+}
+
+static int special_section_entry_size(struct section *sec)
+{
+ unsigned int reloc_size;
+
+ if ((sec->sh.sh_flags & SHF_MERGE) && sec->sh.sh_entsize)
+ return sec->sh.sh_entsize;
+
+ if (!sec->rsec)
+ return 0;
+
+ /* Check for a simple array of pointers */
+ reloc_size = arch_reloc_size(sec->rsec->relocs);
+ if (sec_size(sec) == reloc_size * sec_num_entries(sec->rsec))
+ return reloc_size;
+
+ return 0;
+}
+
+static int create_fake_symbol(struct elf *elf, struct section *sec,
+ unsigned long offset, size_t size)
+{
+ char name[SYM_NAME_LEN];
+ unsigned int type;
+ static int ctr;
+ char *c;
+
+ if (snprintf_check(name, SYM_NAME_LEN, "__DISCARD_%s_%d", sec->name, ctr++))
+ return -1;
+
+ for (c = name; *c; c++)
+ if (*c == '.')
+ *c = '_';
+
+ /*
+ * STT_NOTYPE: Prevent objtool from validating .altinstr_replacement
+ * while still allowing objdump to disassemble it.
+ */
+ type = is_text_sec(sec) ? STT_NOTYPE : STT_OBJECT;
+ if (!elf_create_symbol(elf, name, sec, STB_LOCAL, type, offset, size))
+ return -1;
+
+ return 0;
+}
+
+static int clone_special_section(struct elfs *e, struct section *patched_sec)
+{
+ struct symbol *patched_sym;
+ unsigned int entry_size;
+ unsigned long offset;
+
+ entry_size = special_section_entry_size(patched_sec);
+ if (!entry_size) {
+ /*
+ * Any special section more complex than a simple array of
+ * pointers must have its entry size specified in sh_entsize
+ * (and the SHF_MERGE flag set so the linker preserves it).
+ *
+ * Clang older than version 20 doesn't properly preserve
+ * sh_entsize and will error out here.
+ */
+ ERROR("%s: buggy linker and/or missing sh_entsize", patched_sec->name);
+ return -1;
+ }
+
+ /*
+ * In the patched object, create a fake symbol for each special section
+ * entry. This makes the below extracting of entries much easier.
+ */
+ for (offset = 0; offset < sec_size(patched_sec); offset += entry_size) {
+ if (create_fake_symbol(e->patched, patched_sec, offset, entry_size))
+ return -1;
+
+ /* Symbolize alternative replacements: */
+ if (!strcmp(patched_sec->name, ".altinstructions")) {
+ struct reloc *reloc;
+ unsigned char size;
+
+ reloc = find_reloc_by_dest(e->patched, patched_sec, offset + ALT_NEW_OFFSET);
+ if (!reloc) {
+ ERROR_FUNC(patched_sec, offset + ALT_NEW_OFFSET, "can't find new reloc");
+ return -1;
+ }
+
+ size = *(unsigned char *)(patched_sec->data->d_buf + offset + ALT_NEW_LEN_OFFSET);
+
+ if (create_fake_symbol(e->patched, reloc->sym->sec,
+ reloc->sym->offset + reloc_addend(reloc), size))
+ return -1;
+ }
+ }
+
+ /*
+ * Extract all special section entries (and their dependencies) which
+ * reference included functions.
+ */
+ sec_for_each_sym(patched_sec, patched_sym) {
+ int ret;
+
+ if (!is_object_sym(patched_sym))
+ continue;
+
+ if (!should_keep_special_sym(e->patched, patched_sym))
+ continue;
+
+ ret = validate_special_section_klp_reloc(e, patched_sym);
+ if (ret < 0)
+ return -1;
+ if (ret > 0)
+ continue;
+
+ if (!clone_symbol(e, patched_sym, true))
+ return -1;
+ }
+
+ return 0;
+}
+
+/* Extract only the needed bits from special sections */
+static int clone_special_sections(struct elfs *e)
+{
+ struct section *patched_sec;
+
+ for_each_sec(e->patched, patched_sec) {
+ if (is_special_section(patched_sec)) {
+ if (clone_special_section(e, patched_sec))
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Create __klp_objects and __klp_funcs sections which are intermediate
+ * sections provided as input to the patch module's init code for building the
+ * klp_patch, klp_object and klp_func structs for the livepatch API.
+ */
+static int create_klp_sections(struct elfs *e)
+{
+ size_t obj_size = sizeof(struct klp_object_ext);
+ size_t func_size = sizeof(struct klp_func_ext);
+ struct section *obj_sec, *funcs_sec, *str_sec;
+ struct symbol *funcs_sym, *str_sym, *sym;
+ char sym_name[SYM_NAME_LEN];
+ unsigned int nr_funcs = 0;
+ const char *modname;
+ void *obj_data;
+ s64 addend;
+
+ obj_sec = elf_create_section_pair(e->out, KLP_OBJECTS_SEC, obj_size, 0, 0);
+ if (!obj_sec)
+ return -1;
+
+ funcs_sec = elf_create_section_pair(e->out, KLP_FUNCS_SEC, func_size, 0, 0);
+ if (!funcs_sec)
+ return -1;
+
+ funcs_sym = elf_create_section_symbol(e->out, funcs_sec);
+ if (!funcs_sym)
+ return -1;
+
+ str_sec = elf_create_section(e->out, KLP_STRINGS_SEC, 0, 0,
+ SHT_PROGBITS, 1,
+ SHF_ALLOC | SHF_STRINGS | SHF_MERGE);
+ if (!str_sec)
+ return -1;
+
+ if (elf_add_string(e->out, str_sec, "") == -1)
+ return -1;
+
+ str_sym = elf_create_section_symbol(e->out, str_sec);
+ if (!str_sym)
+ return -1;
+
+ /* allocate klp_object_ext */
+ obj_data = elf_add_data(e->out, obj_sec, NULL, obj_size);
+ if (!obj_data)
+ return -1;
+
+ modname = find_modname(e);
+ if (!modname)
+ return -1;
+
+ /* klp_object_ext.name */
+ if (strcmp(modname, "vmlinux")) {
+ addend = elf_add_string(e->out, str_sec, modname);
+ if (addend == -1)
+ return -1;
+
+ if (!elf_create_reloc(e->out, obj_sec,
+ offsetof(struct klp_object_ext, name),
+ str_sym, addend, R_ABS64))
+ return -1;
+ }
+
+ /* klp_object_ext.funcs */
+ if (!elf_create_reloc(e->out, obj_sec, offsetof(struct klp_object_ext, funcs),
+ funcs_sym, 0, R_ABS64))
+ return -1;
+
+ for_each_sym(e->out, sym) {
+ unsigned long offset = nr_funcs * func_size;
+ unsigned long sympos;
+ void *func_data;
+
+ if (!is_func_sym(sym) || sym->cold || !sym->clone || !sym->clone->changed)
+ continue;
+
+ /* allocate klp_func_ext */
+ func_data = elf_add_data(e->out, funcs_sec, NULL, func_size);
+ if (!func_data)
+ return -1;
+
+ /* klp_func_ext.old_name */
+ addend = elf_add_string(e->out, str_sec, sym->clone->twin->name);
+ if (addend == -1)
+ return -1;
+
+ if (!elf_create_reloc(e->out, funcs_sec,
+ offset + offsetof(struct klp_func_ext, old_name),
+ str_sym, addend, R_ABS64))
+ return -1;
+
+ /* klp_func_ext.new_func */
+ if (!elf_create_reloc(e->out, funcs_sec,
+ offset + offsetof(struct klp_func_ext, new_func),
+ sym, 0, R_ABS64))
+ return -1;
+
+ /* klp_func_ext.sympos */
+ BUILD_BUG_ON(sizeof(sympos) != sizeof_field(struct klp_func_ext, sympos));
+ sympos = find_sympos(e->orig, sym->clone->twin);
+ if (sympos == ULONG_MAX)
+ return -1;
+ memcpy(func_data + offsetof(struct klp_func_ext, sympos), &sympos,
+ sizeof_field(struct klp_func_ext, sympos));
+
+ nr_funcs++;
+ }
+
+ /* klp_object_ext.nr_funcs */
+ BUILD_BUG_ON(sizeof(nr_funcs) != sizeof_field(struct klp_object_ext, nr_funcs));
+ memcpy(obj_data + offsetof(struct klp_object_ext, nr_funcs), &nr_funcs,
+ sizeof_field(struct klp_object_ext, nr_funcs));
+
+ /*
+ * Find callback pointers created by KLP_PRE_PATCH_CALLBACK() and
+ * friends, and add them to the klp object.
+ */
+
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_PRE_PATCH_PREFIX "%s", modname))
+ return -1;
+
+ sym = find_symbol_by_name(e->out, sym_name);
+ if (sym) {
+ struct reloc *reloc;
+
+ reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+ if (!elf_create_reloc(e->out, obj_sec,
+ offsetof(struct klp_object_ext, callbacks) +
+ offsetof(struct klp_callbacks, pre_patch),
+ reloc->sym, reloc_addend(reloc), R_ABS64))
+ return -1;
+ }
+
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_POST_PATCH_PREFIX "%s", modname))
+ return -1;
+
+ sym = find_symbol_by_name(e->out, sym_name);
+ if (sym) {
+ struct reloc *reloc;
+
+ reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+ if (!elf_create_reloc(e->out, obj_sec,
+ offsetof(struct klp_object_ext, callbacks) +
+ offsetof(struct klp_callbacks, post_patch),
+ reloc->sym, reloc_addend(reloc), R_ABS64))
+ return -1;
+ }
+
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_PRE_UNPATCH_PREFIX "%s", modname))
+ return -1;
+
+ sym = find_symbol_by_name(e->out, sym_name);
+ if (sym) {
+ struct reloc *reloc;
+
+ reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+ if (!elf_create_reloc(e->out, obj_sec,
+ offsetof(struct klp_object_ext, callbacks) +
+ offsetof(struct klp_callbacks, pre_unpatch),
+ reloc->sym, reloc_addend(reloc), R_ABS64))
+ return -1;
+ }
+
+ if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_POST_UNPATCH_PREFIX "%s", modname))
+ return -1;
+
+ sym = find_symbol_by_name(e->out, sym_name);
+ if (sym) {
+ struct reloc *reloc;
+
+ reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+ if (!elf_create_reloc(e->out, obj_sec,
+ offsetof(struct klp_object_ext, callbacks) +
+ offsetof(struct klp_callbacks, post_unpatch),
+ reloc->sym, reloc_addend(reloc), R_ABS64))
+ return -1;
+ }
+
+ return 0;
+}
+
+/*
+ * Copy all .modinfo import_ns= tags to ensure all namespaced exported symbols
+ * can be accessed via normal relocs.
+ */
+static int copy_import_ns(struct elfs *e)
+{
+ struct section *patched_sec, *out_sec = NULL;
+ char *import_ns, *data_end;
+
+ patched_sec = find_section_by_name(e->patched, ".modinfo");
+ if (!patched_sec)
+ return 0;
+
+ import_ns = patched_sec->data->d_buf;
+ if (!import_ns)
+ return 0;
+
+ for (data_end = import_ns + sec_size(patched_sec);
+ import_ns < data_end;
+ import_ns += strlen(import_ns) + 1) {
+
+ import_ns = memmem(import_ns, data_end - import_ns, "import_ns=", 10);
+ if (!import_ns)
+ return 0;
+
+ if (!out_sec) {
+ out_sec = find_section_by_name(e->out, ".modinfo");
+ if (!out_sec) {
+ out_sec = elf_create_section(e->out, ".modinfo", 0,
+ patched_sec->sh.sh_entsize,
+ patched_sec->sh.sh_type,
+ patched_sec->sh.sh_addralign,
+ patched_sec->sh.sh_flags);
+ if (!out_sec)
+ return -1;
+ }
+ }
+
+ if (!elf_add_data(e->out, out_sec, import_ns, strlen(import_ns) + 1))
+ return -1;
+ }
+
+ return 0;
+}
+
+int cmd_klp_diff(int argc, const char **argv)
+{
+ struct elfs e = {0};
+
+ argc = parse_options(argc, argv, klp_diff_options, klp_diff_usage, 0);
+ if (argc != 3)
+ usage_with_options(klp_diff_usage, klp_diff_options);
+
+ objname = argv[0];
+
+ e.orig = elf_open_read(argv[0], O_RDONLY);
+ e.patched = elf_open_read(argv[1], O_RDONLY);
+ e.out = NULL;
+
+ if (!e.orig || !e.patched)
+ return -1;
+
+ if (read_exports())
+ return -1;
+
+ if (read_sym_checksums(e.orig))
+ return -1;
+
+ if (read_sym_checksums(e.patched))
+ return -1;
+
+ if (correlate_symbols(&e))
+ return -1;
+
+ if (mark_changed_functions(&e))
+ return 0;
+
+ e.out = elf_create_file(&e.orig->ehdr, argv[2]);
+ if (!e.out)
+ return -1;
+
+ if (clone_included_functions(&e))
+ return -1;
+
+ if (clone_special_sections(&e))
+ return -1;
+
+ if (create_klp_sections(&e))
+ return -1;
+
+ if (copy_import_ns(&e))
+ return -1;
+
+ if (elf_write(e.out))
+ return -1;
+
+ return elf_close(e.out);
+}
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index 5c8b974ad0f9..c8f611c1320d 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -16,8 +16,6 @@
#include <objtool/objtool.h>
#include <objtool/warn.h>
-bool help;
-
static struct objtool_file file;
struct objtool_file *objtool_open_read(const char *filename)
@@ -71,6 +69,39 @@ int objtool_pv_add(struct objtool_file *f, int idx, struct symbol *func)
return 0;
}
+char *top_level_dir(const char *file)
+{
+ ssize_t len, self_len, file_len;
+ char self[PATH_MAX], *str;
+ int i;
+
+ len = readlink("/proc/self/exe", self, sizeof(self) - 1);
+ if (len <= 0)
+ return NULL;
+ self[len] = '\0';
+
+ for (i = 0; i < 3; i++) {
+ char *s = strrchr(self, '/');
+ if (!s)
+ return NULL;
+ *s = '\0';
+ }
+
+ self_len = strlen(self);
+ file_len = strlen(file);
+
+ str = malloc(self_len + file_len + 2);
+ if (!str)
+ return NULL;
+
+ memcpy(str, self, self_len);
+ str[self_len] = '/';
+ strcpy(str + self_len + 1, file);
+
+ return str;
+}
+
+
int main(int argc, const char **argv)
{
static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED";
@@ -79,5 +110,11 @@ int main(int argc, const char **argv)
exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);
pager_init(UNUSED);
+ if (argc > 1 && !strcmp(argv[1], "klp")) {
+ argc--;
+ argv++;
+ return cmd_klp(argc, argv);
+ }
+
return objtool_run(argc, argv);
}
diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
index 81d120d05442..e1d98fb03157 100755
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -16,6 +16,7 @@ arch/x86/include/asm/orc_types.h
arch/x86/include/asm/emulate_prefix.h
arch/x86/lib/x86-opcode-map.txt
arch/x86/tools/gen-insn-attr-x86.awk
+include/linux/livepatch_external.h
include/linux/static_call_types.h
"
diff --git a/tools/objtool/weak.c b/tools/objtool/weak.c
index d83f607733b0..d6562f292259 100644
--- a/tools/objtool/weak.c
+++ b/tools/objtool/weak.c
@@ -8,6 +8,8 @@
#include <stdbool.h>
#include <errno.h>
#include <objtool/objtool.h>
+#include <objtool/arch.h>
+#include <objtool/builtin.h>
#define UNSUPPORTED(name) \
({ \
@@ -24,3 +26,8 @@ int __weak orc_create(struct objtool_file *file)
{
UNSUPPORTED("ORC");
}
+
+int __weak cmd_klp(int argc, const char **argv)
+{
+ UNSUPPORTED("klp");
+}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 53/64] objtool/klp: Add --debug option to show cloning decisions
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (51 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 52/64] objtool/klp: Introduce klp diff subcommand for diffing object files Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 54/64] objtool/klp: Add post-link subcommand to finalize livepatch modules Josh Poimboeuf
` (10 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a --debug option to klp diff which prints cloning decisions and an
indented dependency tree for all cloned symbols and relocations. This
helps visualize which symbols and relocations were included and why.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/include/objtool/warn.h | 21 ++++++++
tools/objtool/klp-diff.c | 75 ++++++++++++++++++++++++++++
tools/objtool/objtool.c | 3 ++
3 files changed, 99 insertions(+)
diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index 29173a1368d7..e88322d97573 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -102,6 +102,10 @@ static inline char *offstr(struct section *sec, unsigned long offset)
#define ERROR_FUNC(sec, offset, format, ...) __WARN_FUNC(ERROR_STR, sec, offset, format, ##__VA_ARGS__)
#define ERROR_INSN(insn, format, ...) WARN_FUNC(insn->sec, insn->offset, format, ##__VA_ARGS__)
+extern bool debug;
+extern int indent;
+
+static inline void unindent(int *unused) { indent--; }
#define __dbg(format, ...) \
fprintf(stderr, \
@@ -110,6 +114,23 @@ static inline char *offstr(struct section *sec, unsigned long offset)
objname ? ": " : "", \
##__VA_ARGS__)
+#define dbg(args...) \
+({ \
+ if (unlikely(debug)) \
+ __dbg(args); \
+})
+
+#define __dbg_indent(format, ...) \
+({ \
+ if (unlikely(debug)) \
+ __dbg("%*s" format, indent * 8, "", ##__VA_ARGS__); \
+})
+
+#define dbg_indent(args...) \
+ int __attribute__((cleanup(unindent))) __dummy_##__COUNTER__; \
+ __dbg_indent(args); \
+ indent++
+
#define dbg_checksum(func, insn, checksum) \
({ \
if (unlikely(insn->sym && insn->sym->pfunc && \
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index 85c6a480ecdb..c9320ce39578 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -37,6 +37,8 @@ static const char * const klp_diff_usage[] = {
};
static const struct option klp_diff_options[] = {
+ OPT_GROUP("Options:"),
+ OPT_BOOLEAN('d', "debug", &debug, "enable debug output"),
OPT_END(),
};
@@ -47,6 +49,38 @@ static inline u32 str_hash(const char *str)
return jhash(str, strlen(str), 0);
}
+static char *escape_str(const char *orig)
+{
+ size_t len = 0;
+ const char *a;
+ char *b, *new;
+
+ for (a = orig; *a; a++) {
+ switch (*a) {
+ case '\001': len += 5; break;
+ case '\n':
+ case '\t': len += 2; break;
+ default: len++;
+ }
+ }
+
+ new = malloc(len + 1);
+ if (!new)
+ return NULL;
+
+ for (a = orig, b = new; *a; a++) {
+ switch (*a) {
+ case '\001': memcpy(b, "<SOH>", 5); b += 5; break;
+ case '\n': *b++ = '\\'; *b++ = 'n'; break;
+ case '\t': *b++ = '\\'; *b++ = 't'; break;
+ default: *b++ = *a;
+ }
+ }
+
+ *b = '\0';
+ return new;
+}
+
static int read_exports(void)
{
const char *symvers = "Module.symvers";
@@ -527,6 +561,28 @@ static struct symbol *__clone_symbol(struct elf *elf, struct symbol *patched_sym
return out_sym;
}
+static const char *sym_type(struct symbol *sym)
+{
+ switch (sym->type) {
+ case STT_NOTYPE: return "NOTYPE";
+ case STT_OBJECT: return "OBJECT";
+ case STT_FUNC: return "FUNC";
+ case STT_SECTION: return "SECTION";
+ case STT_FILE: return "FILE";
+ default: return "UNKNOWN";
+ }
+}
+
+static const char *sym_bind(struct symbol *sym)
+{
+ switch (sym->bind) {
+ case STB_LOCAL: return "LOCAL";
+ case STB_GLOBAL: return "GLOBAL";
+ case STB_WEAK: return "WEAK";
+ default: return "UNKNOWN";
+ }
+}
+
/*
* Copy a symbol to the output object, optionally including its data and
* relocations.
@@ -539,6 +595,8 @@ static struct symbol *clone_symbol(struct elfs *e, struct symbol *patched_sym,
if (patched_sym->clone)
return patched_sym->clone;
+ dbg_indent("%s%s", patched_sym->name, data_too ? " [+DATA]" : "");
+
/* Make sure the prefix gets cloned first */
if (is_func_sym(patched_sym) && data_too) {
pfx = get_func_prefix(patched_sym);
@@ -901,6 +959,8 @@ static int clone_reloc_klp(struct elfs *e, struct reloc *patched_reloc,
klp_sym = find_symbol_by_name(e->out, sym_name);
if (!klp_sym) {
+ __dbg_indent("%s", sym_name);
+
/* STB_WEAK: avoid modpost undefined symbol warnings */
klp_sym = elf_create_symbol(e->out, sym_name, NULL,
STB_WEAK, patched_sym->type, 0, 0);
@@ -949,6 +1009,17 @@ static int clone_reloc_klp(struct elfs *e, struct reloc *patched_reloc,
return 0;
}
+#define dbg_clone_reloc(sec, offset, patched_sym, addend, export, klp) \
+ dbg_indent("%s+0x%lx: %s%s0x%lx [%s%s%s%s%s%s]", \
+ sec->name, offset, patched_sym->name, \
+ addend >= 0 ? "+" : "-", labs(addend), \
+ sym_type(patched_sym), \
+ patched_sym->type == STT_SECTION ? "" : " ", \
+ patched_sym->type == STT_SECTION ? "" : sym_bind(patched_sym), \
+ is_undef_sym(patched_sym) ? " UNDEF" : "", \
+ export ? " EXPORTED" : "", \
+ klp ? " KLP" : "")
+
/* Copy a reloc and its symbol to the output object */
static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
struct section *sec, unsigned long offset)
@@ -968,6 +1039,8 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
klp = klp_reloc_needed(patched_reloc);
+ dbg_clone_reloc(sec, offset, patched_sym, addend, export, klp);
+
if (klp) {
if (clone_reloc_klp(e, patched_reloc, sec, offset, export))
return -1;
@@ -999,6 +1072,8 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
if (is_string_sec(patched_sym->sec)) {
const char *str = patched_sym->sec->data->d_buf + addend;
+ __dbg_indent("\"%s\"", escape_str(str));
+
addend = elf_add_string(e->out, out_sym->sec, str);
if (addend == -1)
return -1;
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index c8f611c1320d..3c26ed561c7e 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -16,6 +16,9 @@
#include <objtool/objtool.h>
#include <objtool/warn.h>
+bool debug;
+int indent;
+
static struct objtool_file file;
struct objtool_file *objtool_open_read(const char *filename)
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 54/64] objtool/klp: Add post-link subcommand to finalize livepatch modules
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (52 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 53/64] objtool/klp: Add --debug option to show cloning decisions Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 55/64] objtool: Disallow duplicate prefix symbols Josh Poimboeuf
` (9 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Livepatch needs some ELF magic which linkers don't like:
- Two relocation sections (.rela*, .klp.rela*) for the same text
section.
- Use of SHN_LIVEPATCH to mark livepatch symbols.
Unfortunately linkers tend to mangle such things. To work around that,
klp diff generates a linker-compliant intermediate binary which encodes
the relevant KLP section/reloc/symbol metadata.
After module linking, the .ko then needs to be converted to an actual
livepatch module. Introduce a new klp post-link subcommand to do so.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/Build | 2 +-
tools/objtool/builtin-klp.c | 1 +
tools/objtool/include/objtool/klp.h | 4 +
tools/objtool/klp-post-link.c | 168 ++++++++++++++++++++++++++++
4 files changed, 174 insertions(+), 1 deletion(-)
create mode 100644 tools/objtool/klp-post-link.c
diff --git a/tools/objtool/Build b/tools/objtool/Build
index 0b01657671d7..8cd71b9a5eef 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -9,7 +9,7 @@ objtool-y += elf.o
objtool-y += objtool.o
objtool-$(BUILD_ORC) += orc_gen.o orc_dump.o
-objtool-$(BUILD_KLP) += builtin-klp.o klp-diff.o
+objtool-$(BUILD_KLP) += builtin-klp.o klp-diff.o klp-post-link.o
objtool-y += libstring.o
objtool-y += libctype.o
diff --git a/tools/objtool/builtin-klp.c b/tools/objtool/builtin-klp.c
index 9b13dd1182af..56d5a5b92f72 100644
--- a/tools/objtool/builtin-klp.c
+++ b/tools/objtool/builtin-klp.c
@@ -14,6 +14,7 @@ struct subcmd {
static struct subcmd subcmds[] = {
{ "diff", "Generate binary diff of two object files", cmd_klp_diff, },
+ { "post-link", "Finalize klp symbols/relocs after module linking", cmd_klp_post_link, },
};
static void cmd_klp_usage(void)
diff --git a/tools/objtool/include/objtool/klp.h b/tools/objtool/include/objtool/klp.h
index 07928fac059b..ad830a7ce55b 100644
--- a/tools/objtool/include/objtool/klp.h
+++ b/tools/objtool/include/objtool/klp.h
@@ -2,6 +2,9 @@
#ifndef _OBJTOOL_KLP_H
#define _OBJTOOL_KLP_H
+#define SHF_RELA_LIVEPATCH 0x00100000
+#define SHN_LIVEPATCH 0xff20
+
/*
* __klp_objects and __klp_funcs are created by klp diff and used by the patch
* module init code to build the klp_patch, klp_object and klp_func structs
@@ -27,5 +30,6 @@ struct klp_reloc {
};
int cmd_klp_diff(int argc, const char **argv);
+int cmd_klp_post_link(int argc, const char **argv);
#endif /* _OBJTOOL_KLP_H */
diff --git a/tools/objtool/klp-post-link.c b/tools/objtool/klp-post-link.c
new file mode 100644
index 000000000000..c013e39957b1
--- /dev/null
+++ b/tools/objtool/klp-post-link.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Read the intermediate KLP reloc/symbol representations created by klp diff
+ * and convert them to the proper format required by livepatch. This needs to
+ * run last to avoid linker wreckage. Linkers don't tend to handle the "two
+ * rela sections for a single base section" case very well, nor do they like
+ * SHN_LIVEPATCH.
+ *
+ * This is the final tool in the livepatch module generation pipeline:
+ *
+ * kernel builds -> objtool klp diff -> module link -> objtool klp post-link
+ */
+
+#include <fcntl.h>
+#include <gelf.h>
+#include <objtool/objtool.h>
+#include <objtool/warn.h>
+#include <objtool/klp.h>
+#include <objtool/util.h>
+#include <linux/livepatch_external.h>
+
+static int fix_klp_relocs(struct elf *elf)
+{
+ struct section *symtab, *klp_relocs;
+
+ klp_relocs = find_section_by_name(elf, KLP_RELOCS_SEC);
+ if (!klp_relocs)
+ return 0;
+
+ symtab = find_section_by_name(elf, ".symtab");
+ if (!symtab) {
+ ERROR("missing .symtab");
+ return -1;
+ }
+
+ for (int i = 0; i < sec_size(klp_relocs) / sizeof(struct klp_reloc); i++) {
+ struct klp_reloc *klp_reloc;
+ unsigned long klp_reloc_off;
+ struct section *sec, *tmp, *klp_rsec;
+ unsigned long offset;
+ struct reloc *reloc;
+ char sym_modname[64];
+ char rsec_name[SEC_NAME_LEN];
+ u64 addend;
+ struct symbol *sym, *klp_sym;
+
+ klp_reloc_off = i * sizeof(*klp_reloc);
+ klp_reloc = klp_relocs->data->d_buf + klp_reloc_off;
+
+ /*
+ * Read __klp_relocs[i]:
+ */
+
+ /* klp_reloc.sec_offset */
+ reloc = find_reloc_by_dest(elf, klp_relocs,
+ klp_reloc_off + offsetof(struct klp_reloc, offset));
+ if (!reloc) {
+ ERROR("malformed " KLP_RELOCS_SEC " section");
+ return -1;
+ }
+
+ sec = reloc->sym->sec;
+ offset = reloc_addend(reloc);
+
+ /* klp_reloc.sym */
+ reloc = find_reloc_by_dest(elf, klp_relocs,
+ klp_reloc_off + offsetof(struct klp_reloc, sym));
+ if (!reloc) {
+ ERROR("malformed " KLP_RELOCS_SEC " section");
+ return -1;
+ }
+
+ klp_sym = reloc->sym;
+ addend = reloc_addend(reloc);
+
+ /* symbol format: .klp.sym.modname.sym_name,sympos */
+ if (sscanf(klp_sym->name + strlen(KLP_SYM_PREFIX), "%55[^.]", sym_modname) != 1)
+ ERROR("can't find modname in klp symbol '%s'", klp_sym->name);
+
+ /*
+ * Create the KLP rela:
+ */
+
+ /* section format: .klp.rela.sec_objname.section_name */
+ if (snprintf_check(rsec_name, SEC_NAME_LEN,
+ KLP_RELOC_SEC_PREFIX "%s.%s",
+ sym_modname, sec->name))
+ return -1;
+
+ klp_rsec = find_section_by_name(elf, rsec_name);
+ if (!klp_rsec) {
+ klp_rsec = elf_create_section(elf, rsec_name, 0,
+ elf_rela_size(elf),
+ SHT_RELA, elf_addr_size(elf),
+ SHF_ALLOC | SHF_INFO_LINK | SHF_RELA_LIVEPATCH);
+ if (!klp_rsec)
+ return -1;
+
+ klp_rsec->sh.sh_link = symtab->idx;
+ klp_rsec->sh.sh_info = sec->idx;
+ klp_rsec->base = sec;
+ }
+
+ tmp = sec->rsec;
+ sec->rsec = klp_rsec;
+ if (!elf_create_reloc(elf, sec, offset, klp_sym, addend, klp_reloc->type))
+ return -1;
+ sec->rsec = tmp;
+
+ /*
+ * Fix up the corresponding KLP symbol:
+ */
+
+ klp_sym->sym.st_shndx = SHN_LIVEPATCH;
+ if (!gelf_update_sym(symtab->data, klp_sym->idx, &klp_sym->sym)) {
+ ERROR_ELF("gelf_update_sym");
+ return -1;
+ }
+
+ /*
+ * Disable the original non-KLP reloc by converting it to R_*_NONE:
+ */
+
+ reloc = find_reloc_by_dest(elf, sec, offset);
+ sym = reloc->sym;
+ sym->sym.st_shndx = SHN_LIVEPATCH;
+ set_reloc_type(elf, reloc, 0);
+ if (!gelf_update_sym(symtab->data, sym->idx, &sym->sym)) {
+ ERROR_ELF("gelf_update_sym");
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * This runs on the livepatch module after all other linking has been done. It
+ * converts the intermediate __klp_relocs section into proper KLP relocs to be
+ * processed by livepatch. This needs to run last to avoid linker wreckage.
+ * Linkers don't tend to handle the "two rela sections for a single base
+ * section" case very well, nor do they appreciate SHN_LIVEPATCH.
+ */
+int cmd_klp_post_link(int argc, const char **argv)
+{
+ struct elf *elf;
+
+ argc--;
+ argv++;
+
+ if (argc != 1) {
+ fprintf(stderr, "%d\n", argc);
+ fprintf(stderr, "usage: objtool link <file.ko>\n");
+ return -1;
+ }
+
+ elf = elf_open_read(argv[0], O_RDWR);
+ if (!elf)
+ return -1;
+
+ if (fix_klp_relocs(elf))
+ return -1;
+
+ if (elf_write(elf))
+ return -1;
+
+ return elf_close(elf);
+}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 55/64] objtool: Disallow duplicate prefix symbols
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (53 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 54/64] objtool/klp: Add post-link subcommand to finalize livepatch modules Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 56/64] objtool: Add base objtool support for livepatch modules Josh Poimboeuf
` (8 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for adding objtool 'check' support for analyzing
livepatch modules, error out if a duplicate prefix symbol is attempted.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 12 +++++++++++-
tools/objtool/elf.c | 9 +++++++++
tools/objtool/include/objtool/elf.h | 3 +++
3 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 9d1f545279a6..c6c99e3fb76f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4221,6 +4221,7 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
for (prev = prev_insn_same_sec(file, insn);
prev;
prev = prev_insn_same_sec(file, prev)) {
+ struct symbol *sym_pfx;
u64 offset;
if (prev->type != INSN_NOP)
@@ -4234,7 +4235,12 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
if (offset < opts.prefix)
continue;
- elf_create_prefix_symbol(file->elf, func, opts.prefix);
+ sym_pfx = elf_create_prefix_symbol(file->elf, func, opts.prefix);
+ if (!sym_pfx) {
+ WARN("duplicate prefix symbol for %s\n", func->name);
+ return -1;
+ }
+
break;
}
@@ -4270,6 +4276,10 @@ static int add_prefix_symbols(struct objtool_file *file)
if (!is_func_sym(func))
continue;
+ /*
+ * Ignore this error on purpose, there are valid
+ * reasons for this to fail.
+ */
add_prefix_symbol(file, func);
}
}
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 16c8d36afe4e..383183e9cf2d 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -945,11 +945,20 @@ elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, size_t size)
size_t namelen = strlen(orig->name) + sizeof("__pfx_");
char name[SYM_NAME_LEN];
unsigned long offset;
+ struct symbol *sym;
snprintf(name, namelen, "__pfx_%s", orig->name);
+ sym = orig;
offset = orig->sym.st_value - size;
+ sec_for_each_sym_continue_reverse(orig->sec, sym) {
+ if (sym->offset < offset)
+ break;
+ if (sym->offset == offset && !strcmp(sym->name, name))
+ return NULL;
+ }
+
return elf_create_symbol(elf, name, orig->sec,
GELF_ST_BIND(orig->sym.st_info),
GELF_ST_TYPE(orig->sym.st_info),
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 903cbcb84e6b..c2a744afd5d5 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -443,6 +443,9 @@ static inline void set_sym_next_reloc(struct reloc *reloc, struct reloc *next)
#define sec_for_each_sym(sec, sym) \
list_for_each_entry(sym, &sec->symbol_list, list)
+#define sec_for_each_sym_continue_reverse(sec, sym) \
+ list_for_each_entry_continue_reverse(sym, &sec->symbol_list, list)
+
#define sec_prev_sym(sym) \
sym->sec && sym->list.prev != &sym->sec->symbol_list ? \
list_prev_entry(sym, list) : NULL
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 56/64] objtool: Add base objtool support for livepatch modules
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (54 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 55/64] objtool: Disallow duplicate prefix symbols Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 57/64] livepatch: Add CONFIG_KLP_BUILD Josh Poimboeuf
` (7 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for klp-build, enable "classic" objtool to work on
livepatch modules:
- Avoid duplicate symbol/section warnings for prefix symbols and the
.static_call_sites and __mcount_loc sections which may have already
been extracted by klp diff.
- Add __klp_funcs to the IBT function pointer section whitelist.
- Prevent KLP symbols from getting incorrectly classified as cold
subfunctions.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 48 +++++++++++++++++++++----
tools/objtool/elf.c | 5 ++-
tools/objtool/include/objtool/elf.h | 1 +
tools/objtool/include/objtool/objtool.h | 2 +-
4 files changed, 48 insertions(+), 8 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c6c99e3fb76f..1eb6489ae459 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3,6 +3,7 @@
* Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
*/
+#define _GNU_SOURCE /* memmem() */
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
@@ -610,6 +611,20 @@ static int init_pv_ops(struct objtool_file *file)
return 0;
}
+static bool is_livepatch_module(struct objtool_file *file)
+{
+ struct section *sec;
+
+ if (!opts.module)
+ return false;
+
+ sec = find_section_by_name(file->elf, ".modinfo");
+ if (!sec)
+ return false;
+
+ return memmem(sec->data->d_buf, sec_size(sec), "\0livepatch=Y", 12);
+}
+
static int create_static_call_sections(struct objtool_file *file)
{
struct static_call_site *site;
@@ -621,7 +636,14 @@ static int create_static_call_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, ".static_call_sites");
if (sec) {
- WARN("file already has .static_call_sites section, skipping");
+ /*
+ * Livepatch modules may have already extracted the static call
+ * site entries to take advantage of vmlinux static call
+ * privileges.
+ */
+ if (!file->klp)
+ WARN("file already has .static_call_sites section, skipping");
+
return 0;
}
@@ -672,7 +694,7 @@ static int create_static_call_sections(struct objtool_file *file)
key_sym = find_symbol_by_name(file->elf, tmp);
if (!key_sym) {
- if (!opts.module) {
+ if (!opts.module || file->klp) {
ERROR("static_call: can't find static_call_key symbol: %s", tmp);
return -1;
}
@@ -891,7 +913,13 @@ static int create_mcount_loc_sections(struct objtool_file *file)
sec = find_section_by_name(file->elf, "__mcount_loc");
if (sec) {
- WARN("file already has __mcount_loc section, skipping");
+ /*
+ * Livepatch modules have already extracted their __mcount_loc
+ * entries to cover the !CONFIG_FTRACE_MCOUNT_USE_OBJTOOL case.
+ */
+ if (!file->klp)
+ WARN("file already has __mcount_loc section, skipping");
+
return 0;
}
@@ -2575,6 +2603,8 @@ static bool validate_branch_enabled(void)
static int decode_sections(struct objtool_file *file)
{
+ file->klp = is_livepatch_module(file);
+
mark_rodata(file);
if (init_pv_ops(file))
@@ -4235,8 +4265,13 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
if (offset < opts.prefix)
continue;
+ /*
+ * Ignore attempts to make duplicate symbols in livepatch
+ * modules. They've already extracted the prefix symbols
+ * except for the newly compiled init.c.
+ */
sym_pfx = elf_create_prefix_symbol(file->elf, func, opts.prefix);
- if (!sym_pfx) {
+ if (!sym_pfx && !file->klp) {
WARN("duplicate prefix symbol for %s\n", func->name);
return -1;
}
@@ -4571,6 +4606,7 @@ static int validate_ibt(struct objtool_file *file)
!strncmp(sec->name, ".debug", 6) ||
!strcmp(sec->name, ".altinstructions") ||
!strcmp(sec->name, ".ibt_endbr_seal") ||
+ !strcmp(sec->name, ".kcfi_traps") ||
!strcmp(sec->name, ".orc_unwind_ip") ||
!strcmp(sec->name, ".retpoline_sites") ||
!strcmp(sec->name, ".smp_locks") ||
@@ -4580,12 +4616,12 @@ static int validate_ibt(struct objtool_file *file)
!strcmp(sec->name, "__bug_table") ||
!strcmp(sec->name, "__ex_table") ||
!strcmp(sec->name, "__jump_table") ||
+ !strcmp(sec->name, "__klp_funcs") ||
!strcmp(sec->name, "__mcount_loc") ||
- !strcmp(sec->name, ".kcfi_traps") ||
!strcmp(sec->name, ".llvm.call-graph-profile") ||
!strcmp(sec->name, ".llvm_bb_addr_map") ||
!strcmp(sec->name, "__tracepoints") ||
- strstr(sec->name, "__patchable_function_entries"))
+ !strcmp(sec->name, "__patchable_function_entries"))
continue;
for_each_reloc(sec->rsec, reloc)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 383183e9cf2d..f9eed5d50de5 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -496,7 +496,10 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
(strstarts(sym->name, "__pfx_") || strstarts(sym->name, "__cfi_")))
sym->prefix = 1;
- if (is_func_sym(sym) && strstr(sym->name, ".cold"))
+ if (strstarts(sym->name, ".klp.sym"))
+ sym->klp = 1;
+
+ if (!sym->klp && is_func_sym(sym) && strstr(sym->name, ".cold"))
sym->cold = 1;
sym->pfunc = sym->cfunc = sym;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index c2a744afd5d5..1212f81f40e0 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -84,6 +84,7 @@ struct symbol {
u8 debug_checksum : 1;
u8 changed : 1;
u8 included : 1;
+ u8 klp : 1;
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index 37e9fe4492d6..731965a742e9 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -30,7 +30,7 @@ struct objtool_file {
struct list_head mcount_loc_list;
struct list_head endbr_list;
struct list_head call_list;
- bool ignore_unreachables, hints, rodata;
+ bool ignore_unreachables, hints, rodata, klp;
unsigned int nr_endbr;
unsigned int nr_endbr_int;
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 57/64] livepatch: Add CONFIG_KLP_BUILD
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (55 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 56/64] objtool: Add base objtool support for livepatch modules Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 58/64] kbuild,objtool: Defer objtool validation step for CONFIG_KLP_BUILD Josh Poimboeuf
` (6 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for introducing klp-build, add a new CONFIG_KLP_BUILD
option. The initial version will only be supported on x86-64.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/Kconfig | 1 +
kernel/livepatch/Kconfig | 12 ++++++++++++
2 files changed, 13 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 62faa62b5959..448c6bfb71d6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -266,6 +266,7 @@ config X86
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_KRETPROBES
select HAVE_RETHOOK
+ select HAVE_KLP_BUILD if X86_64
select HAVE_LIVEPATCH if X86_64
select HAVE_MIXED_BREAKPOINTS_REGS
select HAVE_MOD_ARCH_SPECIFIC
diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig
index 53d51ed619a3..4c0a9c18d0b2 100644
--- a/kernel/livepatch/Kconfig
+++ b/kernel/livepatch/Kconfig
@@ -18,3 +18,15 @@ config LIVEPATCH
module uses the interface provided by this option to register
a patch, causing calls to patched functions to be redirected
to new function code contained in the patch module.
+
+config HAVE_KLP_BUILD
+ bool
+ help
+ Arch supports klp-build
+
+config KLP_BUILD
+ def_bool y
+ depends on LIVEPATCH && HAVE_KLP_BUILD
+ select OBJTOOL
+ help
+ Enable klp-build support
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 58/64] kbuild,objtool: Defer objtool validation step for CONFIG_KLP_BUILD
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (56 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 57/64] livepatch: Add CONFIG_KLP_BUILD Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 59/64] livepatch/klp-build: Introduce fix-patch-lines script to avoid __LINE__ diff noise Josh Poimboeuf
` (5 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
In preparation for klp-build, defer objtool validation for
CONFIG_KLP_BUILD kernels until the final pre-link archive (e.g.,
vmlinux.o, module-foo.o) is built. This will simplify the process of
generating livepatch modules.
Delayed objtool is generally preferred anyway, and is already standard
for IBT and LTO. Eventually the per-translation-unit mode will be
phased out.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
scripts/Makefile.lib | 2 +-
scripts/link-vmlinux.sh | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 15fee73e9289..28a1c08e3b22 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -197,7 +197,7 @@ objtool-args = $(objtool-args-y) \
$(if $(delay-objtool), --link) \
$(if $(part-of-module), --module)
-delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
+delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT),$(CONFIG_KLP_BUILD))
cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@)
cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 51367c2bfc21..59f875236292 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -60,7 +60,8 @@ vmlinux_link()
# skip output file argument
shift
- if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
+ if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ||
+ is_enabled CONFIG_KLP_BUILD; then
# Use vmlinux.o instead of performing the slow LTO link again.
objs=vmlinux.o
libs=
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 59/64] livepatch/klp-build: Introduce fix-patch-lines script to avoid __LINE__ diff noise
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (57 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 58/64] kbuild,objtool: Defer objtool validation step for CONFIG_KLP_BUILD Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 60/64] livepatch/klp-build: Add stub init code for livepatch modules Josh Poimboeuf
` (4 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
The __LINE__ macro creates challenges for binary diffing. When a .patch
file adds or removes lines, it shifts the line numbers for all code
below it.
This can cause the code generation of functions using __LINE__ to change
due to the line number constant being embedded in a MOV instruction,
despite there being no semantic difference.
Avoid such false positives by adding a fix-patch-lines script which can
be used to insert a #line directive in each patch hunk affecting the
line numbering. This script will be used by klp-build, which will be
introduced in a subsequent patch.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
MAINTAINERS | 1 +
scripts/livepatch/fix-patch-lines | 79 +++++++++++++++++++++++++++++++
2 files changed, 80 insertions(+)
create mode 100755 scripts/livepatch/fix-patch-lines
diff --git a/MAINTAINERS b/MAINTAINERS
index 0298d9570ca8..dd622368d74b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14006,6 +14006,7 @@ F: include/linux/livepatch*.h
F: kernel/livepatch/
F: kernel/module/livepatch.c
F: samples/livepatch/
+F: scripts/livepatch/
F: tools/testing/selftests/livepatch/
LLC (802.2)
diff --git a/scripts/livepatch/fix-patch-lines b/scripts/livepatch/fix-patch-lines
new file mode 100755
index 000000000000..73c5e3dea46e
--- /dev/null
+++ b/scripts/livepatch/fix-patch-lines
@@ -0,0 +1,79 @@
+#!/usr/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+#
+# Use #line directives to preserve original __LINE__ numbers across patches to
+# avoid unwanted compilation changes.
+
+BEGIN {
+ in_hunk = 0
+ skip = 0
+}
+
+/^--- / {
+ skip = $2 !~ /\.(c|h)$/
+ print
+ next
+}
+
+/^@@/ {
+ if (skip) {
+ print
+ next
+ }
+
+ in_hunk = 1
+
+ # for @@ -1,3 +1,4 @@:
+ # 1: line number in old file
+ # 3: how many lines the hunk covers in old file
+ # 1: line number in new file
+ # 4: how many lines the hunk covers in new file
+
+ match($0, /^@@ -([0-9]+)(,([0-9]+))? \+([0-9]+)(,([0-9]+))? @@/, m)
+
+ # Set 'cur' to the old file's line number at the start of the hunk. It
+ # gets incremented for every context line and every line removal, so
+ # that it always represents the old file's current line number.
+ cur = m[1]
+
+ # last = last line number of current hunk
+ last = cur + (m[3] ? m[3] : 1) - 1
+
+ need_line_directive = 0
+
+ print
+ next
+}
+
+{
+ if (skip || !in_hunk || $0 ~ /^\\ No newline at end of file/) {
+ print
+ next
+ }
+
+ # change line
+ if ($0 ~ /^[+-]/) {
+ # inject #line after this group of changes
+ need_line_directive = 1
+
+ if ($0 ~ /^-/)
+ cur++
+
+ print
+ next
+ }
+
+ # If this is the first context line after a group of changes, inject
+ # the #line directive to force the compiler to correct the line
+ # numbering to match the original file.
+ if (need_line_directive) {
+ print "+#line " cur
+ need_line_directive = 0
+ }
+
+ if (cur == last)
+ in_hunk = 0
+
+ cur++
+ print
+}
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 60/64] livepatch/klp-build: Add stub init code for livepatch modules
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (58 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 59/64] livepatch/klp-build: Introduce fix-patch-lines script to avoid __LINE__ diff noise Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 61/64] livepatch/klp-build: Introduce klp-build script for generating " Josh Poimboeuf
` (3 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a module initialization stub which can be linked with binary diff
objects to produce a livepatch module.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
scripts/livepatch/init.c | 108 +++++++++++++++++++++++++++++++++++++++
1 file changed, 108 insertions(+)
create mode 100644 scripts/livepatch/init.c
diff --git a/scripts/livepatch/init.c b/scripts/livepatch/init.c
new file mode 100644
index 000000000000..2274d8f5a482
--- /dev/null
+++ b/scripts/livepatch/init.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Init code for a livepatch kernel module
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/livepatch.h>
+
+extern struct klp_object_ext __start_klp_objects[];
+extern struct klp_object_ext __stop_klp_objects[];
+
+static struct klp_patch *patch;
+
+static int __init livepatch_mod_init(void)
+{
+ struct klp_object *objs;
+ unsigned int nr_objs;
+ int ret;
+
+ nr_objs = __stop_klp_objects - __start_klp_objects;
+
+ if (!nr_objs) {
+ pr_err("nothing to patch!\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ patch = kzalloc(sizeof(*patch), GFP_KERNEL);
+ if (!patch) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ objs = kzalloc(sizeof(struct klp_object) * (nr_objs + 1), GFP_KERNEL);
+ if (!objs) {
+ ret = -ENOMEM;
+ goto err_free_patch;
+ }
+
+ for (int i = 0; i < nr_objs; i++) {
+ struct klp_object_ext *obj_ext = __start_klp_objects + i;
+ struct klp_func_ext *funcs_ext = obj_ext->funcs;
+ unsigned int nr_funcs = obj_ext->nr_funcs;
+ struct klp_func *funcs = objs[i].funcs;
+ struct klp_object *obj = objs + i;
+
+ funcs = kzalloc(sizeof(struct klp_func) * (nr_funcs + 1), GFP_KERNEL);
+ if (!funcs) {
+ ret = -ENOMEM;
+ for (int j = 0; j < i; j++)
+ kfree(objs[i].funcs);
+ goto err_free_objs;
+ }
+
+ for (int j = 0; j < nr_funcs; j++) {
+ funcs[j].old_name = funcs_ext[j].old_name;
+ funcs[j].new_func = funcs_ext[j].new_func;
+ funcs[j].old_sympos = funcs_ext[j].sympos;
+ }
+
+ obj->name = obj_ext->name;
+ obj->funcs = funcs;
+
+ memcpy(&obj->callbacks, &obj_ext->callbacks, sizeof(struct klp_callbacks));
+ }
+
+ patch->mod = THIS_MODULE;
+ patch->objs = objs;
+
+ /* TODO patch->states */
+
+#ifdef KLP_NO_REPLACE
+ patch->replace = false;
+#else
+ patch->replace = true;
+#endif
+
+ return klp_enable_patch(patch);
+
+err_free_objs:
+ kfree(objs);
+err_free_patch:
+ kfree(patch);
+err:
+ return ret;
+}
+
+static void __exit livepatch_mod_exit(void)
+{
+ unsigned int nr_objs;
+
+ nr_objs = __stop_klp_objects - __start_klp_objects;
+
+ for (int i = 0; i < nr_objs; i++)
+ kfree(patch->objs[i].funcs);
+
+ kfree(patch->objs);
+ kfree(patch);
+}
+
+module_init(livepatch_mod_init);
+module_exit(livepatch_mod_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_DESCRIPTION("Livepatch module");
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 61/64] livepatch/klp-build: Introduce klp-build script for generating livepatch modules
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (59 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 60/64] livepatch/klp-build: Add stub init code for livepatch modules Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 62/64] livepatch/klp-build: Add --debug option to show cloning decisions Josh Poimboeuf
` (2 subsequent siblings)
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a klp-build script which automates the generation of a livepatch
module from a source .patch file by performing the following steps:
- Builds an original kernel with -function-sections and
-fdata-sections, plus objtool function checksumming.
- Applies the .patch file and rebuilds the kernel using the same
options.
- Runs 'objtool klp diff' to detect changed functions and generate
intermediate binary diff objects.
- Builds a kernel module which links the diff objects with some
livepatch module init code (scripts/livepatch/init.c).
- Finalizes the livepatch module (aka work around linker wreckage)
using 'objtool klp post-link'.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
scripts/livepatch/fix-patch-lines | 2 +-
scripts/livepatch/klp-build | 747 ++++++++++++++++++++++++++++++
tools/objtool/klp-diff.c | 6 +-
3 files changed, 752 insertions(+), 3 deletions(-)
create mode 100755 scripts/livepatch/klp-build
diff --git a/scripts/livepatch/fix-patch-lines b/scripts/livepatch/fix-patch-lines
index 73c5e3dea46e..fa7d4f6592e6 100755
--- a/scripts/livepatch/fix-patch-lines
+++ b/scripts/livepatch/fix-patch-lines
@@ -23,7 +23,7 @@ BEGIN {
in_hunk = 1
- # for @@ -1,3 +1,4 @@:
+ # @@ -1,3 +1,4 @@:
# 1: line number in old file
# 3: how many lines the hunk covers in old file
# 1: line number in new file
diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
new file mode 100755
index 000000000000..b54776fe3161
--- /dev/null
+++ b/scripts/livepatch/klp-build
@@ -0,0 +1,747 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Build a livepatch module
+
+# shellcheck disable=SC1090,SC2155
+
+if (( BASH_VERSINFO[0] < 4 || \
+ (BASH_VERSINFO[0] == 4 && BASH_VERSINFO[1] < 4) )); then
+ echo "error: this script requires bash 4.4+" >&2
+ exit 1
+fi
+
+set -o errexit
+set -o errtrace
+set -o pipefail
+set -o nounset
+
+# Allow doing 'cmd | mapfile -t array' instead of 'mapfile -t array < <(cmd)'.
+# This helps keep execution in pipes so pipefail+errexit can catch errors.
+shopt -s lastpipe
+
+unset SKIP_CLEANUP XTRACE
+
+REPLACE=1
+SHORT_CIRCUIT=0
+JOBS="$(getconf _NPROCESSORS_ONLN)"
+VERBOSE="-s"
+shopt -o xtrace | grep -q 'on' && XTRACE=1
+
+# Avoid removing the previous $TMP_DIR until args have been fully processed.
+KEEP_TMP=1
+
+SCRIPT="$(basename "$0")"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+FIX_PATCH_LINES="$SCRIPT_DIR/fix-patch-lines"
+
+SRC="$(pwd)"
+OBJ="$(pwd)"
+
+CONFIG="$OBJ/.config"
+TMP_DIR="$OBJ/klp-tmp"
+
+ORIG_DIR="$TMP_DIR/orig"
+PATCHED_DIR="$TMP_DIR/patched"
+DIFF_DIR="$TMP_DIR/diff"
+KMOD_DIR="$TMP_DIR/kmod"
+
+STASH_DIR="$TMP_DIR/stash"
+TIMESTAMP="$TMP_DIR/timestamp"
+PATCH_TMP_DIR="$TMP_DIR/tmp"
+
+KLP_DIFF_LOG="$DIFF_DIR/diff.log"
+
+grep0() {
+ command grep "$@" || true
+}
+
+status() {
+ echo "$*"
+}
+
+warn() {
+ echo "error: $SCRIPT: $*" >&2
+}
+
+die() {
+ warn "$@"
+ exit 1
+}
+
+declare -a STASHED_FILES
+
+stash_file() {
+ local file="$1"
+ local rel_file="${file#"$SRC"/}"
+
+ [[ ! -e "$file" ]] && die "no file to stash: $file"
+
+ mkdir -p "$STASH_DIR/$(dirname "$rel_file")"
+ cp -f "$file" "$STASH_DIR/$rel_file"
+
+ STASHED_FILES+=("$rel_file")
+}
+
+restore_files() {
+ local file
+
+ for file in "${STASHED_FILES[@]}"; do
+ mv -f "$STASH_DIR/$file" "$SRC/$file" || warn "can't restore file: $file"
+ done
+
+ STASHED_FILES=()
+}
+
+cleanup() {
+ set +o nounset
+ revert_patches "--recount"
+ restore_files
+ [[ "$KEEP_TMP" -eq 0 ]] && rm -rf "$TMP_DIR"
+ return 0
+}
+
+trap_err() {
+ warn "line ${BASH_LINENO[0]}: '$BASH_COMMAND'"
+}
+
+trap cleanup EXIT INT TERM HUP
+trap trap_err ERR
+
+__usage() {
+ cat <<EOF
+Usage: $SCRIPT [OPTIONS] PATCH_FILE(s)
+Generate a livepatch module.
+
+Options:
+ -j, --jobs=<jobs> Build jobs to run simultaneously [default: $JOBS]
+ -o, --output=<file.ko> Output file [default: livepatch-<patch-name>.ko]
+ --no-replace Disable livepatch atomic replace
+ -v, --verbose Pass V=1 to kernel/module builds
+
+Advanced Options:
+ -S, --short-circuit=STEP Start at build step (requires prior --keep-tmp)
+ 1|orig Build original kernel (default)
+ 2|patched Build patched kernel
+ 3|diff Diff objects
+ 4|kmod Build patch module
+ -T, --keep-tmp Preserve tmp dir on exit
+
+EOF
+}
+
+usage() {
+ __usage >&2
+}
+
+process_args() {
+ local keep_tmp=0
+ local short
+ local long
+ local args
+
+ short="hj:o:vS:T"
+ long="help,jobs:,output:,no-replace,verbose,short-circuit:,keep-tmp"
+
+ args=$(getopt --options "$short" --longoptions "$long" -- "$@") || {
+ echo; usage; exit
+ }
+ eval set -- "$args"
+
+ while true; do
+ case "$1" in
+ -h | --help)
+ usage
+ exit 0
+ ;;
+ -j | --jobs)
+ JOBS="$2"
+ shift 2
+ ;;
+ -o | --output)
+ [[ "$2" != *.ko ]] && die "output filename should end with .ko"
+ OUTFILE="$2"
+ NAME="$(basename "$OUTFILE")"
+ NAME="${NAME%.ko}"
+ NAME="$(module_name_string "$NAME")"
+ shift 2
+ ;;
+ --no-replace)
+ REPLACE=0
+ shift
+ ;;
+ -v | --verbose)
+ VERBOSE="V=1"
+ shift
+ ;;
+ -S | --short-circuit)
+ [[ ! -d "$TMP_DIR" ]] && die "--short-circuit requires preserved klp-tmp dir"
+ keep_tmp=1
+ case "$2" in
+ 1 | orig) SHORT_CIRCUIT=1; ;;
+ 2 | patched) SHORT_CIRCUIT=2; ;;
+ 3 | diff) SHORT_CIRCUIT=3; ;;
+ 4 | mod) SHORT_CIRCUIT=4; ;;
+ *) die "invalid short-circuit step '$2'" ;;
+ esac
+ shift 2
+ ;;
+ -T | --keep-tmp)
+ keep_tmp=1
+ shift
+ ;;
+ --)
+ shift
+ break
+ ;;
+ *)
+ usage
+ exit 1
+ ;;
+ esac
+ done
+
+ if [[ $# -eq 0 ]]; then
+ usage
+ exit 1
+ fi
+
+ KEEP_TMP="$keep_tmp"
+ PATCHES=("$@")
+}
+
+# temporarily disable xtrace for especially verbose code
+xtrace_save() {
+ [[ -v XTRACE ]] && set +x
+ return 0
+}
+
+xtrace_restore() {
+ [[ -v XTRACE ]] && set -x
+ return 0
+}
+
+validate_config() {
+ xtrace_save "reading .config"
+ source "$CONFIG" || die "no .config file in $(dirname "$CONFIG")"
+ xtrace_restore
+
+ [[ -v CONFIG_LIVEPATCH ]] || \
+ die "CONFIG_LIVEPATCH not enabled"
+
+ [[ -v CONFIG_KLP_BUILD ]] || \
+ die "CONFIG_KLP_BUILD not enabled"
+
+ [[ -v CONFIG_GCC_PLUGIN_LATENT_ENTROPY ]] && \
+ die "kernel option 'CONFIG_GCC_PLUGIN_LATENT_ENTROPY' not supported"
+
+ [[ -v CONFIG_GCC_PLUGIN_RANDSTRUCT ]] && \
+ die "kernel option 'CONFIG_GCC_PLUGIN_RANDSTRUCT' not supported"
+
+ return 0
+}
+
+# Only allow alphanumerics and '_' and '-' in the module name. Everything else
+# is replaced with '-'. Also truncate to 55 chars so the full name + NUL
+# terminator fits in the kernel's 56-byte module name array.
+module_name_string() {
+ echo "${1//[^a-zA-Z0-9_-]/-}" | cut -c 1-55
+}
+
+# If the module name wasn't specified on the cmdline with --output, give it a
+# name based on the patch name.
+set_module_name() {
+ [[ -v NAME ]] && return 0
+
+ if [[ "${#PATCHES[@]}" -eq 1 ]]; then
+ NAME="$(basename "${PATCHES[0]}")"
+ NAME="${NAME%.*}"
+ else
+ NAME="patch"
+ fi
+
+ NAME="livepatch-$NAME"
+ NAME="$(module_name_string "$NAME")"
+
+ OUTFILE="$NAME.ko"
+}
+
+# Hardcode the value printed by the localversion script to prevent patch
+# application from appending it with '+' due to a dirty git working tree.
+set_kernelversion() {
+ local file="$SRC/scripts/setlocalversion"
+ local localversion
+
+ stash_file "$file"
+
+ localversion="$(cd "$SRC" && make --no-print-directory kernelversion)"
+ localversion="$(cd "$SRC" && KERNELVERSION="$localversion" ./scripts/setlocalversion)"
+ [[ -z "$localversion" ]] && die "setlocalversion failed"
+
+ sed -i "2i echo $localversion; exit 0" scripts/setlocalversion
+}
+
+get_patch_files() {
+ local patch="$1"
+
+ grep0 -E '^(--- |\+\+\+ )' "$patch" \
+ | gawk '{print $2}' \
+ | sed 's|^[^/]*/||' \
+ | sort -u
+}
+
+# Make sure git re-stats the changed files
+git_refresh() {
+ local patch="$1"
+ local files=()
+
+ [[ ! -e "$SRC/.git" ]] && return
+
+ get_patch_files "$patch" | mapfile -t files
+
+ (
+ cd "$SRC"
+ git update-index -q --refresh -- "${files[@]}"
+ )
+}
+
+check_unsupported_patches() {
+ local patch
+
+ for patch in "${PATCHES[@]}"; do
+ local files=()
+
+ get_patch_files "$patch" | mapfile -t files
+
+ for file in "${files[@]}"; do
+ case "$file" in
+ lib/*|*.S)
+ die "unsupported patch to $file"
+ ;;
+ esac
+ done
+ done
+}
+
+apply_patch() {
+ local patch="$1"
+ shift
+ local extra_args=("$@")
+
+ [[ ! -f "$patch" ]] && die "$patch doesn't exist"
+
+ (
+ cd "$SRC"
+
+ # The sed strips the version signature from 'git format-patch',
+ # otherwise 'git apply --recount' warns.
+ sed -n '/^-- /q;p' "$patch" |
+ git apply "${extra_args[@]}"
+ )
+
+ APPLIED_PATCHES+=("$patch")
+}
+
+revert_patch() {
+ local patch="$1"
+ shift
+ local extra_args=("$@")
+ local tmp=()
+
+ (
+ cd "$SRC"
+
+ sed -n '/^-- /q;p' "$patch" |
+ git apply --reverse "${extra_args[@]}"
+ )
+ git_refresh "$patch"
+
+ for p in "${APPLIED_PATCHES[@]}"; do
+ [[ "$p" == "$patch" ]] && continue
+ tmp+=("$p")
+ done
+
+ APPLIED_PATCHES=("${tmp[@]}")
+}
+
+apply_patches() {
+ local patch
+
+ for patch in "${PATCHES[@]}"; do
+ apply_patch "$patch"
+ done
+}
+
+revert_patches() {
+ local extra_args=("$@")
+ local patches=("${APPLIED_PATCHES[@]}")
+
+ for (( i=${#patches[@]}-1 ; i>=0 ; i-- )) ; do
+ revert_patch "${patches[$i]}" "${extra_args[@]}"
+ done
+
+ APPLIED_PATCHES=()
+}
+
+validate_patches() {
+ check_unsupported_patches
+ apply_patches
+ revert_patches
+}
+
+do_init() {
+ # We're not yet smart enough to handle anything other than in-tree
+ # builds in pwd.
+ [[ ! "$SRC" -ef "$SCRIPT_DIR/../.." ]] && die "please run from the kernel root directory"
+ [[ ! "$OBJ" -ef "$SCRIPT_DIR/../.." ]] && die "please run from the kernel root directory"
+
+ (( SHORT_CIRCUIT <= 1 )) && rm -rf "$TMP_DIR"
+ mkdir -p "$TMP_DIR"
+
+ APPLIED_PATCHES=()
+
+ [[ -x "$FIX_PATCH_LINES" ]] || die "can't find fix-patch-lines"
+
+ validate_config
+ set_module_name
+ set_kernelversion
+}
+
+# Refresh the patch hunk headers, specifically the line numbers and counts.
+refresh_patch() {
+ local patch="$1"
+ local tmpdir="$PATCH_TMP_DIR"
+ local files=()
+
+ rm -rf "$tmpdir"
+ mkdir -p "$tmpdir/a"
+ mkdir -p "$tmpdir/b"
+
+ # Get all source files affected by the patch
+ get_patch_files "$patch" | mapfile -t files
+
+ # Copy orig source files to 'a'
+ ( cd "$SRC" && echo "${files[@]}" | xargs cp --parents --target-directory="$tmpdir/a" )
+
+ # Copy patched source files to 'b'
+ apply_patch "$patch" --recount
+ ( cd "$SRC" && echo "${files[@]}" | xargs cp --parents --target-directory="$tmpdir/b" )
+ revert_patch "$patch" --recount
+
+ # Diff 'a' and 'b' to make a clean patch
+ ( cd "$tmpdir" && git diff --no-index --no-prefix a b > "$patch" ) || true
+}
+
+# Copy the patches to a temporary directory, fix their lines so as not to
+# affect the __LINE__ macro for otherwise unchanged functions further down the
+# file, and update $PATCHES to point to the fixed patches.
+fix_patches() {
+ local idx
+ local i
+
+ rm -f "$TMP_DIR"/*.patch
+
+ idx=0001
+ for i in "${!PATCHES[@]}"; do
+ local old_patch="${PATCHES[$i]}"
+ local tmp_patch="$TMP_DIR/tmp.patch"
+ local patch="${PATCHES[$i]}"
+ local new_patch
+
+ new_patch="$TMP_DIR/$idx-fixed-$(basename "$patch")"
+
+ cp -f "$old_patch" "$tmp_patch"
+ refresh_patch "$tmp_patch"
+ "$FIX_PATCH_LINES" "$tmp_patch" > "$new_patch"
+ refresh_patch "$new_patch"
+
+ PATCHES[i]="$new_patch"
+
+ rm -f "$tmp_patch"
+ idx=$(printf "%04d" $(( 10#$idx + 1 )))
+ done
+}
+
+clean_kernel() {
+ local cmd=()
+
+ cmd=("make")
+ cmd+=("--silent")
+ cmd+=("-j$JOBS")
+ cmd+=("clean")
+
+ (
+ cd "$SRC"
+ "${cmd[@]}"
+ )
+}
+
+build_kernel() {
+ local log="$TMP_DIR/build.log"
+ local objtool_args=()
+ local cmd=()
+
+ objtool_args=("--checksum")
+
+ cmd=("make")
+
+ # When a patch to a kernel module references a newly created unexported
+ # symbol which lives in vmlinux or another kernel module, the patched
+ # kernel build fails with the following error:
+ #
+ # ERROR: modpost: "klp_string" [fs/xfs/xfs.ko] undefined!
+ #
+ # The undefined symbols are working as designed in that case. They get
+ # resolved later when the livepatch module build link pulls all the
+ # disparate objects together into the same kernel module.
+ #
+ # It would be good to have a way to tell modpost to skip checking for
+ # undefined symbols altogether. For now, just convert the error to a
+ # warning with KBUILD_MODPOST_WARN, and grep out the warning to avoid
+ # confusing the user.
+ #
+ cmd+=("KBUILD_MODPOST_WARN=1")
+
+ cmd+=("$VERBOSE")
+ cmd+=("-j$JOBS")
+ cmd+=("KCFLAGS=-ffunction-sections -fdata-sections")
+ cmd+=("OBJTOOL_ARGS=${objtool_args[*]}")
+ cmd+=("vmlinux")
+ cmd+=("modules")
+
+ (
+ cd "$SRC"
+ "${cmd[@]}" \
+ 1> >(tee -a "$log") \
+ 2> >(tee -a "$log" | grep0 -v "modpost.*undefined!" >&2)
+ )
+}
+
+find_objects() {
+ local opts=("$@")
+
+ # Find root-level vmlinux.o and non-root-level .ko files,
+ # excluding klp-tmp/ and .git/
+ find "$OBJ" \( -path "$TMP_DIR" -o -path "$OBJ/.git" -o -regex "$OBJ/[^/][^/]*\.ko" \) -prune -o \
+ -type f "${opts[@]}" \
+ \( -name "*.ko" -o -path "$OBJ/vmlinux.o" \) \
+ -printf '%P\n'
+}
+
+# Copy all .o archives to $ORIG_DIR
+copy_orig_objects() {
+ local files=()
+
+ rm -rf "$ORIG_DIR"
+ mkdir -p "$ORIG_DIR"
+
+ find_objects | mapfile -t files
+
+ xtrace_save "copying orig objects"
+ for _file in "${files[@]}"; do
+ local rel_file="${_file/.ko/.o}"
+ local file="$OBJ/$rel_file"
+ local file_dir="$(dirname "$file")"
+ local orig_file="$ORIG_DIR/$rel_file"
+ local orig_dir="$(dirname "$orig_file")"
+ local cmd_file="$file_dir/.$(basename "$file").cmd"
+
+ [[ ! -f "$file" ]] && die "missing $(basename "$file") for $_file"
+
+ mkdir -p "$orig_dir"
+ cp -f "$file" "$orig_dir"
+ [[ -e "$cmd_file" ]] && cp -f "$cmd_file" "$orig_dir"
+ done
+ xtrace_restore
+
+ mv -f "$TMP_DIR/build.log" "$ORIG_DIR"
+ touch "$TIMESTAMP"
+}
+
+# Copy all changed objects to $PATCHED_DIR
+copy_patched_objects() {
+ local files=()
+ local opts=()
+ local found=0
+
+ rm -rf "$PATCHED_DIR"
+ mkdir -p "$PATCHED_DIR"
+
+ # Note this doesn't work with some configs, thus the 'cmp' below.
+ opts=("-newer")
+ opts+=("$TIMESTAMP")
+
+ find_objects "${opts[@]}" | mapfile -t files
+
+ xtrace_save "copying changed objects"
+ for _file in "${files[@]}"; do
+ local rel_file="${_file/.ko/.o}"
+ local file="$OBJ/$rel_file"
+ local orig_file="$ORIG_DIR/$rel_file"
+ local patched_file="$PATCHED_DIR/$rel_file"
+ local patched_dir="$(dirname "$patched_file")"
+
+ [[ ! -f "$file" ]] && die "missing $(basename "$file") for $_file"
+
+ cmp -s "$orig_file" "$file" && continue
+
+ mkdir -p "$patched_dir"
+ cp -f "$file" "$patched_dir"
+ found=1
+ done
+ xtrace_restore
+
+ (( found == 0 )) && die "no changes detected"
+
+ mv -f "$TMP_DIR/build.log" "$PATCHED_DIR"
+}
+
+# Diff changed objects, writing output object to $DIFF_DIR
+diff_objects() {
+ local log="$KLP_DIFF_LOG"
+ local files=()
+
+ rm -rf "$DIFF_DIR"
+ mkdir -p "$DIFF_DIR"
+
+ find "$PATCHED_DIR" -type f -name "*.o" | mapfile -t files
+ [[ ${#files[@]} -eq 0 ]] && die "no changes detected"
+
+ # Diff all changed objects
+ for file in "${files[@]}"; do
+ local rel_file="${file#"$PATCHED_DIR"/}"
+ local orig_file="$rel_file"
+ local patched_file="$PATCHED_DIR/$rel_file"
+ local out_file="$DIFF_DIR/$rel_file"
+ local cmd=()
+
+ mkdir -p "$(dirname "$out_file")"
+
+ cmd=("$SRC/tools/objtool/objtool")
+ cmd+=("klp")
+ cmd+=("diff")
+ cmd+=("$orig_file")
+ cmd+=("$patched_file")
+ cmd+=("$out_file")
+
+ (
+ cd "$ORIG_DIR"
+ "${cmd[@]}" \
+ 1> >(tee -a "$log") \
+ 2> >(tee -a "$log" >&2) || \
+ die "objtool klp diff failed"
+ )
+ done
+}
+
+# Build and post-process livepatch module in $KMOD_DIR
+build_patch_module() {
+ local makefile="$KMOD_DIR/Kbuild"
+ local log="$KMOD_DIR/build.log"
+ local kmod_file
+ local cflags=()
+ local files=()
+ local cmd=()
+
+ rm -rf "$KMOD_DIR"
+ mkdir -p "$KMOD_DIR"
+
+ cp -f "$SRC/scripts/livepatch/init.c" "$KMOD_DIR"
+
+ echo "obj-m := $NAME.o" > "$makefile"
+ echo -n "$NAME-y := init.o" >> "$makefile"
+
+ find "$DIFF_DIR" -type f -name "*.o" | mapfile -t files
+ [[ ${#files[@]} -eq 0 ]] && die "no changes detected"
+
+ for file in "${files[@]}"; do
+ local rel_file="${file#"$DIFF_DIR"/}"
+ local orig_file="$ORIG_DIR/$rel_file"
+ local orig_dir="$(dirname "$orig_file")"
+ local kmod_file="$KMOD_DIR/$rel_file"
+ local kmod_dir="$(dirname "$kmod_file")"
+ local cmd_file="$orig_dir/.$(basename "$file").cmd"
+
+ mkdir -p "$kmod_dir"
+ cp -f "$file" "$kmod_dir"
+ [[ -e "$cmd_file" ]] && cp -f "$cmd_file" "$kmod_dir"
+
+ # Tell kbuild this is a prebuilt object
+ cp -f "$file" "${kmod_file}_shipped"
+
+ echo -n " $rel_file" >> "$makefile"
+ done
+
+ echo >> "$makefile"
+
+ cflags=("-ffunction-sections")
+ cflags+=("-fdata-sections")
+ [[ $REPLACE -eq 0 ]] && cflags+=("-DKLP_NO_REPLACE")
+
+ cmd=("make")
+ cmd+=("$VERBOSE")
+ cmd+=("-j$JOBS")
+ cmd+=("--directory=.")
+ cmd+=("M=$KMOD_DIR")
+ cmd+=("KCFLAGS=${cflags[*]}")
+
+ # Build a "normal" kernel module with init.c and the diffed objects
+ (
+ cd "$SRC"
+ "${cmd[@]}" \
+ 1> >(tee -a "$log") \
+ 2> >(tee -a "$log" >&2)
+ )
+
+ kmod_file="$KMOD_DIR/$NAME.ko"
+
+ # Save off the intermediate binary for debugging
+ cp -f "$kmod_file" "$kmod_file.orig"
+
+ # Work around issue where slight .config change makes corrupt BTF
+ objcopy --remove-section=.BTF "$kmod_file"
+
+ # Fix (and work around) linker wreckage for klp syms / relocs
+ "$SRC/tools/objtool/objtool" klp post-link "$kmod_file" || die "objtool klp post-link failed"
+
+ cp -f "$kmod_file" "$OUTFILE"
+}
+
+
+################################################################################
+
+process_args "$@"
+do_init
+
+if (( SHORT_CIRCUIT <= 1 )); then
+ status "Validating patches"
+ validate_patches
+ status "Building original kernel"
+ clean_kernel
+ build_kernel
+ status "Copying original object files"
+ copy_orig_objects
+fi
+
+if (( SHORT_CIRCUIT <= 2 )); then
+ status "Fixing patches"
+ fix_patches
+ apply_patches
+ status "Building patched kernel"
+ build_kernel
+ revert_patches
+ status "Copying patched object files"
+ copy_patched_objects
+fi
+
+if (( SHORT_CIRCUIT <= 3 )); then
+ status "Diffing objects"
+ diff_objects
+fi
+
+if (( SHORT_CIRCUIT <= 4 )); then
+ status "Building patch module: $OUTFILE"
+ build_patch_module
+fi
+
+status "SUCCESS"
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index c9320ce39578..15b554b53da6 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -240,10 +240,12 @@ static struct symbol *next_file_symbol(struct elf *elf, struct symbol *sym)
static bool is_uncorrelated_static_local(struct symbol *sym)
{
static const char * const vars[] = {
- "__key.",
- "__warned.",
"__already_done.",
"__func__.",
+ "__key.",
+ "__warned.",
+ "_entry.",
+ "_entry_ptr.",
"_rs.",
"descriptor.",
"CSWTCH.",
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 62/64] livepatch/klp-build: Add --debug option to show cloning decisions
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (60 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 61/64] livepatch/klp-build: Introduce klp-build script for generating " Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 63/64] livepatch/klp-build: Add --show-first-changed option to show function divergence Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 64/64] livepatch: Introduce source code helpers for livepatch modules Josh Poimboeuf
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a --debug option which gets passed to "objtool klp diff" to enable
debug output related to cloning decisions.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
scripts/livepatch/klp-build | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index b54776fe3161..fe9af53a8476 100755
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -20,7 +20,7 @@ set -o nounset
# This helps keep execution in pipes so pipefail+errexit can catch errors.
shopt -s lastpipe
-unset SKIP_CLEANUP XTRACE
+unset DEBUG_CLONE SKIP_CLEANUP XTRACE
REPLACE=1
SHORT_CIRCUIT=0
@@ -120,6 +120,7 @@ Options:
-v, --verbose Pass V=1 to kernel/module builds
Advanced Options:
+ -d, --debug Show symbol/reloc cloning decisions
-S, --short-circuit=STEP Start at build step (requires prior --keep-tmp)
1|orig Build original kernel (default)
2|patched Build patched kernel
@@ -140,8 +141,8 @@ process_args() {
local long
local args
- short="hj:o:vS:T"
- long="help,jobs:,output:,no-replace,verbose,short-circuit:,keep-tmp"
+ short="hj:o:vdS:T"
+ long="help,jobs:,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"
args=$(getopt --options "$short" --longoptions "$long" -- "$@") || {
echo; usage; exit
@@ -174,6 +175,11 @@ process_args() {
VERBOSE="V=1"
shift
;;
+ -d | --debug)
+ DEBUG_CLONE=1
+ keep_tmp=1
+ shift
+ ;;
-S | --short-circuit)
[[ ! -d "$TMP_DIR" ]] && die "--short-circuit requires preserved klp-tmp dir"
keep_tmp=1
@@ -600,6 +606,7 @@ copy_patched_objects() {
diff_objects() {
local log="$KLP_DIFF_LOG"
local files=()
+ local opts=()
rm -rf "$DIFF_DIR"
mkdir -p "$DIFF_DIR"
@@ -607,6 +614,8 @@ diff_objects() {
find "$PATCHED_DIR" -type f -name "*.o" | mapfile -t files
[[ ${#files[@]} -eq 0 ]] && die "no changes detected"
+ [[ -v DEBUG_CLONE ]] && opts=("--debug")
+
# Diff all changed objects
for file in "${files[@]}"; do
local rel_file="${file#"$PATCHED_DIR"/}"
@@ -620,6 +629,7 @@ diff_objects() {
cmd=("$SRC/tools/objtool/objtool")
cmd+=("klp")
cmd+=("diff")
+ (( ${#opts[@]} > 0 )) && cmd+=("${opts[@]}")
cmd+=("$orig_file")
cmd+=("$patched_file")
cmd+=("$out_file")
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 63/64] livepatch/klp-build: Add --show-first-changed option to show function divergence
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (61 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 62/64] livepatch/klp-build: Add --debug option to show cloning decisions Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 64/64] livepatch: Introduce source code helpers for livepatch modules Josh Poimboeuf
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add a --show-first-changed option to identify where changed functions
begin to diverge:
- Parse 'objtool klp diff' output to find changed functions.
- Run objtool again on each object with --debug-checksum=<funcs>.
- Diff the per-instruction checksum debug output to locate the first
differing instruction.
This can be useful for quickly determining where and why a function
changed.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
scripts/livepatch/klp-build | 82 +++++++++++++++++++++++++++++++++++--
1 file changed, 78 insertions(+), 4 deletions(-)
diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index fe9af53a8476..e47056f75475 100755
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -20,7 +20,7 @@ set -o nounset
# This helps keep execution in pipes so pipefail+errexit can catch errors.
shopt -s lastpipe
-unset DEBUG_CLONE SKIP_CLEANUP XTRACE
+unset DEBUG_CLONE DIFF_CHECKSUM SKIP_CLEANUP XTRACE
REPLACE=1
SHORT_CIRCUIT=0
@@ -114,6 +114,7 @@ Usage: $SCRIPT [OPTIONS] PATCH_FILE(s)
Generate a livepatch module.
Options:
+ -f, --show-first-changed Show address of first changed instruction
-j, --jobs=<jobs> Build jobs to run simultaneously [default: $JOBS]
-o, --output=<file.ko> Output file [default: livepatch-<patch-name>.ko]
--no-replace Disable livepatch atomic replace
@@ -141,8 +142,8 @@ process_args() {
local long
local args
- short="hj:o:vdS:T"
- long="help,jobs:,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"
+ short="hfj:o:vdS:T"
+ long="help,show-first-changed,jobs:,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"
args=$(getopt --options "$short" --longoptions "$long" -- "$@") || {
echo; usage; exit
@@ -155,6 +156,10 @@ process_args() {
usage
exit 0
;;
+ -f | --show-first-changed)
+ DIFF_CHECKSUM=1
+ shift
+ ;;
-j | --jobs)
JOBS="$2"
shift 2
@@ -622,6 +627,7 @@ diff_objects() {
local orig_file="$rel_file"
local patched_file="$PATCHED_DIR/$rel_file"
local out_file="$DIFF_DIR/$rel_file"
+ local filter=()
local cmd=()
mkdir -p "$(dirname "$out_file")"
@@ -634,16 +640,80 @@ diff_objects() {
cmd+=("$patched_file")
cmd+=("$out_file")
+ if [[ -v DIFF_CHECKSUM ]]; then
+ filter=("grep0")
+ filter+=("-Ev")
+ filter+=("DEBUG: .*checksum: ")
+ else
+ filter=("cat")
+ fi
+
(
cd "$ORIG_DIR"
"${cmd[@]}" \
1> >(tee -a "$log") \
- 2> >(tee -a "$log" >&2) || \
+ 2> >(tee -a "$log" | "${filter[@]}" >&2) || \
die "objtool klp diff failed"
)
done
}
+# For each changed object, run objtool with --debug-checksum to get the
+# per-instruction checksums, and then diff those to find the first changed
+# instruction for each function.
+diff_checksums() {
+ local orig_log="$ORIG_DIR/checksum.log"
+ local patched_log="$PATCHED_DIR/checksum.log"
+ local -A funcs
+ local cmd=()
+ local line
+ local file
+ local func
+
+ gawk '/\.o: changed function: / {
+ sub(/:$/, "", $1)
+ print $1, $NF
+ }' "$KLP_DIFF_LOG" | mapfile -t lines
+
+ for line in "${lines[@]}"; do
+ read -r file func <<< "$line"
+ if [[ ! -v funcs["$file"] ]]; then
+ funcs["$file"]="$func"
+ else
+ funcs["$file"]+=" $func"
+ fi
+ done
+
+ cmd=("$SRC/tools/objtool/objtool")
+ cmd+=("--checksum")
+ cmd+=("--link")
+ cmd+=("--dry-run")
+
+ for file in "${!funcs[@]}"; do
+ local opt="--debug-checksum=${funcs[$file]// /,}"
+
+ (
+ cd "$ORIG_DIR"
+ "${cmd[@]}" "$opt" "$file" &> "$orig_log" || \
+ ( cat "$orig_log" >&2; die "objtool --debug-checksum failed" )
+
+ cd "$PATCHED_DIR"
+ "${cmd[@]}" "$opt" "$file" &> "$patched_log" || \
+ ( cat "$patched_log" >&2; die "objtool --debug-checksum failed" )
+ )
+
+ for func in ${funcs[$file]}; do
+ diff <( grep0 -E "^DEBUG: .*checksum: $func " "$orig_log" | sed "s|$ORIG_DIR/||") \
+ <( grep0 -E "^DEBUG: .*checksum: $func " "$patched_log" | sed "s|$PATCHED_DIR/||") \
+ | gawk '/^< DEBUG: / {
+ gsub(/:/, "")
+ printf "%s: %s: %s\n", $3, $5, $6
+ exit
+ }' || true
+ done
+ done
+}
+
# Build and post-process livepatch module in $KMOD_DIR
build_patch_module() {
local makefile="$KMOD_DIR/Kbuild"
@@ -747,6 +817,10 @@ fi
if (( SHORT_CIRCUIT <= 3 )); then
status "Diffing objects"
diff_objects
+ if [[ -v DIFF_CHECKSUM ]]; then
+ status "Finding first changed instructions"
+ diff_checksums
+ fi
fi
if (( SHORT_CIRCUIT <= 4 )); then
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* [PATCH v3 64/64] livepatch: Introduce source code helpers for livepatch modules
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
` (62 preceding siblings ...)
2025-06-26 23:55 ` [PATCH v3 63/64] livepatch/klp-build: Add --show-first-changed option to show function divergence Josh Poimboeuf
@ 2025-06-26 23:55 ` Josh Poimboeuf
63 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-26 23:55 UTC (permalink / raw)
To: x86
Cc: linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
Add some helper macros which can be used by livepatch source .patch
files to register callbacks, convert static calls to regular calls where
needed, and patch syscalls.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
include/linux/livepatch_helpers.h | 79 +++++++++++++++++++++++++++++++
1 file changed, 79 insertions(+)
create mode 100644 include/linux/livepatch_helpers.h
diff --git a/include/linux/livepatch_helpers.h b/include/linux/livepatch_helpers.h
new file mode 100644
index 000000000000..337bee91d7da
--- /dev/null
+++ b/include/linux/livepatch_helpers.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_LIVEPATCH_HELPERS_H
+#define _LINUX_LIVEPATCH_HELPERS_H
+
+/*
+ * Interfaces for use by livepatch patches
+ */
+
+#include <linux/syscalls.h>
+#include <linux/livepatch.h>
+
+#ifdef MODULE
+#define KLP_OBJNAME __KBUILD_MODNAME
+#else
+#define KLP_OBJNAME vmlinux
+#endif
+
+/* Livepatch callback registration */
+
+#define KLP_CALLBACK_PTRS ".discard.klp_callback_ptrs"
+
+#define KLP_PRE_PATCH_CALLBACK(func) \
+ klp_pre_patch_t __used __section(KLP_CALLBACK_PTRS) \
+ __PASTE(__KLP_PRE_PATCH_PREFIX, KLP_OBJNAME) = func
+
+#define KLP_POST_PATCH_CALLBACK(func) \
+ klp_post_patch_t __used __section(KLP_CALLBACK_PTRS) \
+ __PASTE(__KLP_POST_PATCH_PREFIX, KLP_OBJNAME) = func
+
+#define KLP_PRE_UNPATCH_CALLBACK(func) \
+ klp_pre_unpatch_t __used __section(KLP_CALLBACK_PTRS) \
+ __PASTE(__KLP_PRE_UNPATCH_PREFIX, KLP_OBJNAME) = func
+
+#define KLP_POST_UNPATCH_CALLBACK(func) \
+ klp_post_unpatch_t __used __section(KLP_CALLBACK_PTRS) \
+ __PASTE(__KLP_POST_UNPATCH_PREFIX, KLP_OBJNAME) = func
+
+/*
+ * KLP_STATIC_CALL
+ *
+ * Replace static_call() usage with this macro when create-diff-object
+ * recommends it due to the original static call key living in a module.
+ *
+ * This converts the static call to a regular indirect call.
+ */
+#define KLP_STATIC_CALL(name) \
+ ((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func))
+
+/* Syscall patching */
+
+#define KLP_SYSCALL_DEFINE1(name, ...) KLP_SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
+#define KLP_SYSCALL_DEFINE2(name, ...) KLP_SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)
+#define KLP_SYSCALL_DEFINE3(name, ...) KLP_SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
+#define KLP_SYSCALL_DEFINE4(name, ...) KLP_SYSCALL_DEFINEx(4, _##name, __VA_ARGS__)
+#define KLP_SYSCALL_DEFINE5(name, ...) KLP_SYSCALL_DEFINEx(5, _##name, __VA_ARGS__)
+#define KLP_SYSCALL_DEFINE6(name, ...) KLP_SYSCALL_DEFINEx(6, _##name, __VA_ARGS__)
+
+#define KLP_SYSCALL_DEFINEx(x, sname, ...) \
+ __KLP_SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
+
+#ifdef CONFIG_X86_64
+// TODO move this to arch/x86/include/asm/syscall_wrapper.h and share code
+#define __KLP_SYSCALL_DEFINEx(x, name, ...) \
+ static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
+ static inline long __klp_do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
+ __X64_SYS_STUBx(x, name, __VA_ARGS__) \
+ __IA32_SYS_STUBx(x, name, __VA_ARGS__) \
+ static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
+ { \
+ long ret = __klp_do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
+ __MAP(x,__SC_TEST,__VA_ARGS__); \
+ __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
+ return ret; \
+ } \
+ static inline long __klp_do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
+
+#endif
+
+#endif /* _LINUX_LIVEPATCH_HELPERS_H */
--
2.49.0
^ permalink raw reply related [flat|nested] 82+ messages in thread
* Re: [PATCH v3 17/64] objtool: Fix weak symbol detection
2025-06-26 23:55 ` [PATCH v3 17/64] objtool: Fix weak symbol detection Josh Poimboeuf
@ 2025-06-27 9:13 ` Peter Zijlstra
2025-06-27 15:42 ` Josh Poimboeuf
0 siblings, 1 reply; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-27 9:13 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Thu, Jun 26, 2025 at 04:55:04PM -0700, Josh Poimboeuf wrote:
> find_symbol_hole_containing() fails to find a symbol hole (aka stripped
> weak symbol) if its section has no symbols before the hole. This breaks
> weak symbol detection if -ffunction-sections is enabled.
>
> Fix that by allowing the interval tree to contain section symbols, which
> are always at offset zero for a given section.
>
> Fixes a bunch of (-ffunction-sections) warnings like:
>
> vmlinux.o: warning: objtool: .text.__x64_sys_io_setup+0x10: unreachable instruction
>
> Fixes: 4adb23686795 ("objtool: Ignore extra-symbol code")
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> tools/include/linux/interval_tree_generic.h | 2 +-
> tools/objtool/elf.c | 8 ++++----
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/tools/include/linux/interval_tree_generic.h b/tools/include/linux/interval_tree_generic.h
> index aaa8a0767aa3..c0ec9dbdfbaf 100644
> --- a/tools/include/linux/interval_tree_generic.h
> +++ b/tools/include/linux/interval_tree_generic.h
> @@ -77,7 +77,7 @@ ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, \
> * Cond2: start <= ITLAST(node) \
> */ \
> \
> -static ITSTRUCT * \
> +ITSTATIC ITSTRUCT * \
> ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
> { \
> while (true) { \
IIRC this file is a direct copy from the kernel; this should probably be
changed in both?
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 01/64] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text
2025-06-26 23:54 ` [PATCH v3 01/64] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text Josh Poimboeuf
@ 2025-06-27 9:34 ` Heiko Carstens
0 siblings, 0 replies; 82+ messages in thread
From: Heiko Carstens @ 2025-06-27 9:34 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Vasily Gorbik, Alexander Gordeev
On Thu, Jun 26, 2025 at 04:54:48PM -0700, Josh Poimboeuf wrote:
> The s390 indirect thunks are placed in the .text.__s390_indirect_jump_*
> sections.
>
> Certain config options which enable -ffunction-sections have a custom
> version of the TEXT_TEXT macro:
>
> .text.[0-9a-zA-Z_]*
>
> That unintentionally matches the thunk sections, causing them to get
> grouped with normal text rather than being handled by their intended
> rule later in the script:
>
> *(.text.*_indirect_*)
>
> Fix that by adding another period to the thunk section names, following
> the kernel's general convention for distinguishing code-generated text
> sections from compiler-generated ones.
>
> Cc: Heiko Carstens <hca@linux.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> arch/s390/include/asm/nospec-insn.h | 2 +-
> arch/s390/kernel/vmlinux.lds.S | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
Acked-by: Heiko Carstens <hca@linux.ibm.com>
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 26/64] objtool: Add section/symbol type helpers
2025-06-26 23:55 ` [PATCH v3 26/64] objtool: Add section/symbol type helpers Josh Poimboeuf
@ 2025-06-27 10:29 ` Peter Zijlstra
2025-06-27 16:36 ` Josh Poimboeuf
0 siblings, 1 reply; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-27 10:29 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Thu, Jun 26, 2025 at 04:55:13PM -0700, Josh Poimboeuf wrote:
> @@ -177,11 +178,71 @@ static inline unsigned int elf_text_rela_type(struct elf *elf)
> return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
> }
>
> +static inline bool sym_has_sec(struct symbol *sym)
> +{
> + return sym->sec->idx;
> +}
> +
> +static inline bool is_null_sym(struct symbol *sym)
> +{
> + return !sym->idx;
> +}
> +
> +static inline bool is_sec_sym(struct symbol *sym)
> +{
> + return sym->type == STT_SECTION;
> +}
> +
> +static inline bool is_object_sym(struct symbol *sym)
> +{
> + return sym->type == STT_OBJECT;
> +}
> +
> +static inline bool is_func_sym(struct symbol *sym)
> +{
> + return sym->type == STT_FUNC;
> +}
> +
> +static inline bool is_file_sym(struct symbol *sym)
> +{
> + return sym->type == STT_FILE;
> +}
> +
> +static inline bool is_notype_sym(struct symbol *sym)
> +{
> + return sym->type == STT_NOTYPE;
> +}
> +
> +static inline bool is_global_sym(struct symbol *sym)
> +{
> + return sym->bind == STB_GLOBAL;
> +}
> +
> +static inline bool is_weak_sym(struct symbol *sym)
> +{
> + return sym->bind == STB_WEAK;
> +}
> +
> +static inline bool is_local_sym(struct symbol *sym)
> +{
> + return sym->bind == STB_LOCAL;
> +}
> +
> static inline bool is_reloc_sec(struct section *sec)
> {
> return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
> }
>
> +static inline bool is_string_sec(struct section *sec)
> +{
> + return sec->sh.sh_flags & SHF_STRINGS;
> +}
> +
> +static inline bool is_text_sec(struct section *sec)
> +{
> + return sec->sh.sh_flags & SHF_EXECINSTR;
> +}
> +
> static inline bool sec_changed(struct section *sec)
> {
> return sec->_changed;
> @@ -222,6 +283,11 @@ static inline bool is_32bit_reloc(struct reloc *reloc)
> return reloc->sec->sh.sh_entsize < 16;
> }
>
> +static inline unsigned long sec_size(struct section *sec)
> +{
> + return sec->sh.sh_size;
> +}
> +
Naming seems inconsistent, there are:
sym_has_sec(), sec_changed() and sec_size()
which have the object first, but then most new ones are:
is_foo_sym() and is_foo_sec()
which have the object last.
Can we make this consistent and do something like:
s/is_\([^_]*\)_\(sym\|sec\)/\2_is_\1/
?
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 29/64] objtool: Mark prefix functions
2025-06-26 23:55 ` [PATCH v3 29/64] objtool: Mark prefix functions Josh Poimboeuf
@ 2025-06-27 10:31 ` Peter Zijlstra
2025-06-27 16:53 ` Josh Poimboeuf
0 siblings, 1 reply; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-27 10:31 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Thu, Jun 26, 2025 at 04:55:16PM -0700, Josh Poimboeuf wrote:
> In preparation for the objtool klp diff subcommand, introduce a flag to
> identify __pfx_*() and __cfi_*() functions in advance so they don't need
> to be manually identified every time a check is needed.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> tools/objtool/check.c | 3 +--
> tools/objtool/elf.c | 4 ++++
> tools/objtool/include/objtool/elf.h | 6 ++++++
> 3 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 80bafcdb42af..55cc3a2a21c9 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -3564,8 +3564,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
>
> if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
> /* Ignore KCFI type preambles, which always fall through */
> - if (!strncmp(func->name, "__cfi_", 6) ||
> - !strncmp(func->name, "__pfx_", 6))
> + if (is_prefix_func(func))
> return 0;
>
> if (file->ignore_unreachables)
> diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
> index 59568381486c..1bb86151243a 100644
> --- a/tools/objtool/elf.c
> +++ b/tools/objtool/elf.c
> @@ -442,6 +442,10 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
> elf_hash_add(symbol, &sym->hash, sym->idx);
> elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
>
> + if (is_func_sym(sym) &&
> + (strstarts(sym->name, "__pfx_") || strstarts(sym->name, "__cfi_")))
> + sym->prefix = 1;
> +
> if (is_func_sym(sym) && strstr(sym->name, ".cold"))
> sym->cold = 1;
> sym->pfunc = sym->cfunc = sym;
> diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
> index f41496b0ad8f..842faec1b9a9 100644
> --- a/tools/objtool/include/objtool/elf.h
> +++ b/tools/objtool/include/objtool/elf.h
> @@ -72,6 +72,7 @@ struct symbol {
> u8 frame_pointer : 1;
> u8 ignore : 1;
> u8 cold : 1;
> + u8 prefix : 1;
> struct list_head pv_target;
> struct reloc *relocs;
> struct section *group_sec;
> @@ -229,6 +230,11 @@ static inline bool is_local_sym(struct symbol *sym)
> return sym->bind == STB_LOCAL;
> }
>
> +static inline bool is_prefix_func(struct symbol *sym)
> +{
> + return is_func_sym(sym) && sym->prefix;
> +}
func_is_prefix() ?
Also, since we only ever set sym->prefix when is_func_sym(), this helper
could avoid checking that again.
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels
2025-06-26 23:55 ` [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels Josh Poimboeuf
@ 2025-06-27 10:48 ` Peter Zijlstra
2025-06-27 16:55 ` Josh Poimboeuf
0 siblings, 1 reply; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-27 10:48 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Thu, Jun 26, 2025 at 04:55:31PM -0700, Josh Poimboeuf wrote:
> In preparation for the objtool klp diff subcommand, define the entry
> size for the __jump_table section in its ELF header. This will allow
> tooling to extract individual entries.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> arch/x86/include/asm/jump_label.h | 17 +++++++++++------
> kernel/bounds.c | 4 ++++
> 2 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
> index cd21554b3675..7a6b0e5d85c1 100644
> --- a/arch/x86/include/asm/jump_label.h
> +++ b/arch/x86/include/asm/jump_label.h
> @@ -12,12 +12,17 @@
> #include <linux/stringify.h>
> #include <linux/types.h>
>
> -#define JUMP_TABLE_ENTRY(key, label) \
> - ".pushsection __jump_table, \"a\"\n\t" \
> - _ASM_ALIGN "\n\t" \
> - ".long 1b - . \n\t" \
> - ".long " label " - . \n\t" \
> - _ASM_PTR " " key " - . \n\t" \
> +#ifndef COMPILE_OFFSETS
> +#include <generated/bounds.h>
> +#endif
> +
> +#define JUMP_TABLE_ENTRY(key, label) \
> + ".pushsection __jump_table, \"aM\", @progbits, " \
> + __stringify(JUMP_ENTRY_SIZE) "\n\t" \
Argh, can you please not do this line-break. Yes it'll be long, but this
is most confusing.
> + _ASM_ALIGN "\n\t" \
> + ".long 1b - . \n\t" \
> + ".long " label " - . \n\t" \
> + _ASM_PTR " " key " - . \n\t" \
> ".popsection \n\t"
>
> /* This macro is also expanded on the Rust side. */
> diff --git a/kernel/bounds.c b/kernel/bounds.c
> index 02b619eb6106..e4c7ded3dc48 100644
> --- a/kernel/bounds.c
> +++ b/kernel/bounds.c
> @@ -13,6 +13,7 @@
> #include <linux/kbuild.h>
> #include <linux/log2.h>
> #include <linux/spinlock_types.h>
> +#include <linux/jump_label.h>
>
> int main(void)
> {
> @@ -29,6 +30,9 @@ int main(void)
> #else
> DEFINE(LRU_GEN_WIDTH, 0);
> DEFINE(__LRU_REFS_WIDTH, 0);
> +#endif
> +#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && defined(CONFIG_JUMP_LABEL)
How is HAVE_ARCH_JUMP_LABEL_RELATIVE relevant here?
> + DEFINE(JUMP_ENTRY_SIZE, sizeof(struct jump_entry));
> #endif
> /* End of constants */
>
> --
> 2.49.0
>
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 45/64] x86/static_call: Define ELF section entry size of static calls
2025-06-26 23:55 ` [PATCH v3 45/64] x86/static_call: Define ELF section entry size of static calls Josh Poimboeuf
@ 2025-06-27 10:51 ` Peter Zijlstra
0 siblings, 0 replies; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-27 10:51 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Thu, Jun 26, 2025 at 04:55:32PM -0700, Josh Poimboeuf wrote:
> In preparation for the objtool klp diff subcommand, define the entry
> size for the .static_call_sites section in its ELF header. This will
> allow tooling to extract individual entries.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> arch/x86/include/asm/static_call.h | 3 ++-
> include/linux/static_call.h | 6 ------
> include/linux/static_call_types.h | 6 ++++++
> kernel/bounds.c | 4 ++++
> tools/include/linux/static_call_types.h | 6 ++++++
> tools/objtool/check.c | 11 +++++++++--
> 6 files changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/include/asm/static_call.h b/arch/x86/include/asm/static_call.h
> index 41502bd2afd6..e03ad9bbbf59 100644
> --- a/arch/x86/include/asm/static_call.h
> +++ b/arch/x86/include/asm/static_call.h
> @@ -58,7 +58,8 @@
> ARCH_DEFINE_STATIC_CALL_TRAMP(name, __static_call_return0)
>
> #define ARCH_ADD_TRAMP_KEY(name) \
> - asm(".pushsection .static_call_tramp_key, \"a\" \n" \
> + asm(".pushsection .static_call_tramp_key, \"aM\", @progbits, " \
> + __stringify(STATIC_CALL_TRAMP_KEY_SIZE) "\n" \
More horrifically confusing indenting.
> ".long " STATIC_CALL_TRAMP_STR(name) " - . \n" \
> ".long " STATIC_CALL_KEY_STR(name) " - . \n" \
> ".popsection \n")
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 46/64] x86/extable: Define ELF section entry size for exception table
2025-06-26 23:55 ` [PATCH v3 46/64] x86/extable: Define ELF section entry size for exception table Josh Poimboeuf
@ 2025-06-27 10:52 ` Peter Zijlstra
0 siblings, 0 replies; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-27 10:52 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Thu, Jun 26, 2025 at 04:55:33PM -0700, Josh Poimboeuf wrote:
> @@ -193,7 +193,8 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
> ".purgem extable_type_reg\n"
>
> # define _ASM_EXTABLE_TYPE(from, to, type) \
> - " .pushsection \"__ex_table\",\"a\"\n" \
> + " .pushsection __ex_table, \"aM\", @progbits, " \
> + __stringify(EXTABLE_SIZE) "\n" \
> " .balign 4\n" \
> " .long (" #from ") - .\n" \
> " .long (" #to ") - .\n" \
> @@ -201,7 +202,8 @@ static __always_inline __pure void *rip_rel_ptr(void *p)
> " .popsection\n"
>
> # define _ASM_EXTABLE_TYPE_REG(from, to, type, reg) \
> - " .pushsection \"__ex_table\",\"a\"\n" \
> + " .pushsection __ex_table, \"aM\", @progbits, " \
> + __stringify(EXTABLE_SIZE) "\n" \
> " .balign 4\n" \
> " .long (" #from ") - .\n" \
> " .long (" #to ") - .\n" \
This style is much better.
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 42/64] kbuild,x86: Fix special section module permissions
2025-06-26 23:55 ` [PATCH v3 42/64] kbuild,x86: Fix special section module permissions Josh Poimboeuf
@ 2025-06-27 10:53 ` Peter Zijlstra
2025-06-27 17:34 ` Josh Poimboeuf
0 siblings, 1 reply; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-27 10:53 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Masahiro Yamada
On Thu, Jun 26, 2025 at 04:55:29PM -0700, Josh Poimboeuf wrote:
> An upcoming patch will add the SHF_MERGE flag to x86 __jump_table and
> __bug_table so their entry sizes can be defined in inline asm.
>
> However, those sections have SHF_WRITE, which the Clang linker (lld)
> explicitly forbids combining with SHF_MERGE.
>
> Those sections are modified at runtime and must remain writable. While
> SHF_WRITE is ignored by vmlinux, it's still needed for modules.
>
> To work around the linker interference, remove SHF_WRITE during
> compilation and restore it after linking the module.
This is vile... but I'm not sure I have a better solution.
Eventually we should get the toolchains fixed, but we can't very well
mandate clang-21+ to build x86 just yet.
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 17/64] objtool: Fix weak symbol detection
2025-06-27 9:13 ` Peter Zijlstra
@ 2025-06-27 15:42 ` Josh Poimboeuf
0 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-27 15:42 UTC (permalink / raw)
To: Peter Zijlstra
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Fri, Jun 27, 2025 at 11:13:10AM +0200, Peter Zijlstra wrote:
> On Thu, Jun 26, 2025 at 04:55:04PM -0700, Josh Poimboeuf wrote:
> > find_symbol_hole_containing() fails to find a symbol hole (aka stripped
> > weak symbol) if its section has no symbols before the hole. This breaks
> > weak symbol detection if -ffunction-sections is enabled.
> >
> > Fix that by allowing the interval tree to contain section symbols, which
> > are always at offset zero for a given section.
> >
> > Fixes a bunch of (-ffunction-sections) warnings like:
> >
> > vmlinux.o: warning: objtool: .text.__x64_sys_io_setup+0x10: unreachable instruction
> >
> > Fixes: 4adb23686795 ("objtool: Ignore extra-symbol code")
> > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> > ---
> > tools/include/linux/interval_tree_generic.h | 2 +-
> > tools/objtool/elf.c | 8 ++++----
> > 2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/include/linux/interval_tree_generic.h b/tools/include/linux/interval_tree_generic.h
> > index aaa8a0767aa3..c0ec9dbdfbaf 100644
> > --- a/tools/include/linux/interval_tree_generic.h
> > +++ b/tools/include/linux/interval_tree_generic.h
> > @@ -77,7 +77,7 @@ ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, \
> > * Cond2: start <= ITLAST(node) \
> > */ \
> > \
> > -static ITSTRUCT * \
> > +ITSTATIC ITSTRUCT * \
> > ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
> > { \
> > while (true) { \
>
> IIRC this file is a direct copy from the kernel; this should probably be
> changed in both?
Ok. We should probably enforce that with the sync-check script.
--
Josh
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 26/64] objtool: Add section/symbol type helpers
2025-06-27 10:29 ` Peter Zijlstra
@ 2025-06-27 16:36 ` Josh Poimboeuf
2025-06-30 7:29 ` Peter Zijlstra
0 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-27 16:36 UTC (permalink / raw)
To: Peter Zijlstra
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Fri, Jun 27, 2025 at 12:29:30PM +0200, Peter Zijlstra wrote:
> Naming seems inconsistent, there are:
>
> sym_has_sec(), sec_changed() and sec_size()
>
> which have the object first, but then most new ones are:
>
> is_foo_sym() and is_foo_sec()
>
> which have the object last.
For the "is_()" variants, I read them as:
"is a(n) <adjective> <noun>"
e.g.:
is_undef_sym(): "is an UNDEF symbol"
is_file_sym(): "is a FILE symbol"
is_string_sec() "is a STRING section"
Nerding out on English for a second, many of those adjectives can be
read as noun adjuncts, e.g. "chicken soup", where a noun functions as an
adjective.
If we changed those to:
"is <noun> <adjective>?"
or
"is <noun> a <noun>?"
then it doesn't always read correctly:
is_sym_file(): "is symbol a file?"
is_sec_string(): "is section a string?"
--
Josh
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 29/64] objtool: Mark prefix functions
2025-06-27 10:31 ` Peter Zijlstra
@ 2025-06-27 16:53 ` Josh Poimboeuf
0 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-27 16:53 UTC (permalink / raw)
To: Peter Zijlstra
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Fri, Jun 27, 2025 at 12:31:58PM +0200, Peter Zijlstra wrote:
> > +static inline bool is_prefix_func(struct symbol *sym)
> > +{
> > + return is_func_sym(sym) && sym->prefix;
> > +}
>
> func_is_prefix() ?
is the function a prefix though?
> Also, since we only ever set sym->prefix when is_func_sym(), this helper
> could avoid checking that again.
Indeed...
--
Josh
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels
2025-06-27 10:48 ` Peter Zijlstra
@ 2025-06-27 16:55 ` Josh Poimboeuf
2025-06-30 7:35 ` Peter Zijlstra
0 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-27 16:55 UTC (permalink / raw)
To: Peter Zijlstra
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Fri, Jun 27, 2025 at 12:48:18PM +0200, Peter Zijlstra wrote:
> > +#define JUMP_TABLE_ENTRY(key, label) \
> > + ".pushsection __jump_table, \"aM\", @progbits, " \
> > + __stringify(JUMP_ENTRY_SIZE) "\n\t" \
>
> Argh, can you please not do this line-break. Yes it'll be long, but this
> is most confusing.
Yeah, I'll go indent that like the extable one.
> > @@ -29,6 +30,9 @@ int main(void)
> > #else
> > DEFINE(LRU_GEN_WIDTH, 0);
> > DEFINE(__LRU_REFS_WIDTH, 0);
> > +#endif
> > +#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && defined(CONFIG_JUMP_LABEL)
>
> How is HAVE_ARCH_JUMP_LABEL_RELATIVE relevant here?
#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
struct jump_entry {
s32 code;
s32 target;
long key; // key may be far away from the core kernel under KASLR
};
--
Josh
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 42/64] kbuild,x86: Fix special section module permissions
2025-06-27 10:53 ` Peter Zijlstra
@ 2025-06-27 17:34 ` Josh Poimboeuf
2025-06-30 7:31 ` Peter Zijlstra
0 siblings, 1 reply; 82+ messages in thread
From: Josh Poimboeuf @ 2025-06-27 17:34 UTC (permalink / raw)
To: Peter Zijlstra
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Masahiro Yamada
On Fri, Jun 27, 2025 at 12:53:28PM +0200, Peter Zijlstra wrote:
> On Thu, Jun 26, 2025 at 04:55:29PM -0700, Josh Poimboeuf wrote:
> > An upcoming patch will add the SHF_MERGE flag to x86 __jump_table and
> > __bug_table so their entry sizes can be defined in inline asm.
> >
> > However, those sections have SHF_WRITE, which the Clang linker (lld)
> > explicitly forbids combining with SHF_MERGE.
> >
> > Those sections are modified at runtime and must remain writable. While
> > SHF_WRITE is ignored by vmlinux, it's still needed for modules.
> >
> > To work around the linker interference, remove SHF_WRITE during
> > compilation and restore it after linking the module.
>
> This is vile... but I'm not sure I have a better solution.
>
> Eventually we should get the toolchains fixed, but we can't very well
> mandate clang-21+ to build x86 just yet.
Yeah, I really hate this too. I really tried to find something better,
including mucking with the linker script, but this was unfortunately the
only thing that worked.
Though, looking at it again, I realize we can localize the pain to Clang
(and the makefile) by leaving the code untouched and instead strip
SHF_WRITE before the link and re-add it afterwards. Then we can tie
this horrible hack to specific Clang versions when it gets fixed.
Something like so:
diff --git a/arch/Kconfig b/arch/Kconfig
index a3308a220f86..350ea5df5e8d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1314,6 +1314,9 @@ config HAVE_NOINSTR_HACK
config HAVE_NOINSTR_VALIDATION
bool
+config NEED_MODULE_PERMISSIONS_FIX
+ bool
+
config HAVE_UACCESS_VALIDATION
bool
select OBJTOOL
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 71019b3b54ea..0cac13c03a90 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -310,6 +310,7 @@ config X86
select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
select IRQ_FORCED_THREADING
select LOCK_MM_AND_FIND_VMA
+ select NEED_MODULE_PERMISSIONS_FIX if LD_IS_LLD
select NEED_PER_CPU_EMBED_FIRST_CHUNK
select NEED_PER_CPU_PAGE_FIRST_CHUNK
select NEED_SG_DMA_LENGTH
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 542ba462ed3e..cbc3213427ba 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -28,12 +28,37 @@ ccflags-remove-y := $(CC_FLAGS_CFI)
.module-common.o: $(srctree)/scripts/module-common.c FORCE
$(call if_changed_rule,cc_o_c)
+
+ifdef CONFIG_NEED_MODULE_PERMISSIONS_FIX
+
+# The LLVM linker forbids SHF_MERGE+SHF_WRITE. Hack around that by
+# temporarily removing SHF_WRITE from affected sections before linking.
+
+cmd_fix_mod_permissions_pre_link = \
+ $(OBJCOPY) --set-section-flags __jump_table=alloc,readonly \
+ --set-section-flags __bug_table=alloc,readonly $@ \
+ --set-section-flags .static_call_sites=alloc,readonly $@
+
+cmd_fix_mod_permissions_post_link = \
+ $(OBJCOPY) --set-section-flags __jump_table=alloc,data \
+ --set-section-flags __bug_table=alloc,data $@ \
+ --set-section-flags .static_call_sites=alloc,data $@
+
+endif # CONFIG_NEED_MODULE_PERMISSIONS_FIX
+
+
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o = \
$(LD) -r $(KBUILD_LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-T $(objtree)/scripts/module.lds -o $@ $(filter %.o, $^)
+define rule_ld_ko_o
+ $(call cmd,fix_mod_permissions_pre_link)
+ $(call cmd_and_savecmd,ld_ko_o)
+ $(call cmd,fix_mod_permissions_post_link)
+endef
+
quiet_cmd_btf_ko = BTF [M] $@
cmd_btf_ko = \
if [ ! -f $(objtree)/vmlinux ]; then \
@@ -46,14 +71,11 @@ quiet_cmd_btf_ko = BTF [M] $@
# Same as newer-prereqs, but allows to exclude specified extra dependencies
newer_prereqs_except = $(filter-out $(PHONY) $(1),$?)
-# Same as if_changed, but allows to exclude specified extra dependencies
-if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
- $(cmd); \
- printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
+if_changed_rule_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check),$(rule_$(1)),@:)
# Re-generate module BTFs if either module's .ko or vmlinux changed
%.ko: %.o %.mod.o .module-common.o $(objtree)/scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),$(objtree)/vmlinux) FORCE
- +$(call if_changed_except,ld_ko_o,$(objtree)/vmlinux)
+ +$(call if_changed_rule_except,ld_ko_o,$(objtree)/vmlinux)
ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+$(if $(newer-prereqs),$(call cmd,btf_ko))
endif
^ permalink raw reply related [flat|nested] 82+ messages in thread
* Re: [PATCH v3 26/64] objtool: Add section/symbol type helpers
2025-06-27 16:36 ` Josh Poimboeuf
@ 2025-06-30 7:29 ` Peter Zijlstra
2025-07-01 19:05 ` Josh Poimboeuf
0 siblings, 1 reply; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-30 7:29 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Fri, Jun 27, 2025 at 09:36:08AM -0700, Josh Poimboeuf wrote:
> On Fri, Jun 27, 2025 at 12:29:30PM +0200, Peter Zijlstra wrote:
> > Naming seems inconsistent, there are:
> >
> > sym_has_sec(), sec_changed() and sec_size()
> >
> > which have the object first, but then most new ones are:
> >
> > is_foo_sym() and is_foo_sec()
> >
> > which have the object last.
>
> For the "is_()" variants, I read them as:
>
> "is a(n) <adjective> <noun>"
>
> e.g.:
>
> is_undef_sym(): "is an UNDEF symbol"
> is_file_sym(): "is a FILE symbol"
> is_string_sec() "is a STRING section"
>
> Nerding out on English for a second, many of those adjectives can be
> read as noun adjuncts, e.g. "chicken soup", where a noun functions as an
> adjective.
>
> If we changed those to:
>
> "is <noun> <adjective>?"
>
> or
>
> "is <noun> a <noun>?"
>
> then it doesn't always read correctly:
>
> is_sym_file(): "is symbol a file?"
> is_sec_string(): "is section a string?"
English aside; things like sym_*() create a clear namespace, and
sym_is_file() can be easily read as sym::is_file().
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 42/64] kbuild,x86: Fix special section module permissions
2025-06-27 17:34 ` Josh Poimboeuf
@ 2025-06-30 7:31 ` Peter Zijlstra
0 siblings, 0 replies; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-30 7:31 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch, Masahiro Yamada
On Fri, Jun 27, 2025 at 10:34:15AM -0700, Josh Poimboeuf wrote:
> On Fri, Jun 27, 2025 at 12:53:28PM +0200, Peter Zijlstra wrote:
> > On Thu, Jun 26, 2025 at 04:55:29PM -0700, Josh Poimboeuf wrote:
> > > An upcoming patch will add the SHF_MERGE flag to x86 __jump_table and
> > > __bug_table so their entry sizes can be defined in inline asm.
> > >
> > > However, those sections have SHF_WRITE, which the Clang linker (lld)
> > > explicitly forbids combining with SHF_MERGE.
> > >
> > > Those sections are modified at runtime and must remain writable. While
> > > SHF_WRITE is ignored by vmlinux, it's still needed for modules.
> > >
> > > To work around the linker interference, remove SHF_WRITE during
> > > compilation and restore it after linking the module.
> >
> > This is vile... but I'm not sure I have a better solution.
> >
> > Eventually we should get the toolchains fixed, but we can't very well
> > mandate clang-21+ to build x86 just yet.
>
> Yeah, I really hate this too. I really tried to find something better,
> including mucking with the linker script, but this was unfortunately the
> only thing that worked.
>
> Though, looking at it again, I realize we can localize the pain to Clang
> (and the makefile) by leaving the code untouched and instead strip
> SHF_WRITE before the link and re-add it afterwards. Then we can tie
> this horrible hack to specific Clang versions when it gets fixed.
Oh yeah, that might be nicer indeed!
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels
2025-06-27 16:55 ` Josh Poimboeuf
@ 2025-06-30 7:35 ` Peter Zijlstra
0 siblings, 0 replies; 82+ messages in thread
From: Peter Zijlstra @ 2025-06-30 7:35 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Fri, Jun 27, 2025 at 09:55:30AM -0700, Josh Poimboeuf wrote:
> On Fri, Jun 27, 2025 at 12:48:18PM +0200, Peter Zijlstra wrote:
> > > +#define JUMP_TABLE_ENTRY(key, label) \
> > > + ".pushsection __jump_table, \"aM\", @progbits, " \
> > > + __stringify(JUMP_ENTRY_SIZE) "\n\t" \
> >
> > Argh, can you please not do this line-break. Yes it'll be long, but this
> > is most confusing.
>
> Yeah, I'll go indent that like the extable one.
>
> > > @@ -29,6 +30,9 @@ int main(void)
> > > #else
> > > DEFINE(LRU_GEN_WIDTH, 0);
> > > DEFINE(__LRU_REFS_WIDTH, 0);
> > > +#endif
> > > +#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && defined(CONFIG_JUMP_LABEL)
> >
> > How is HAVE_ARCH_JUMP_LABEL_RELATIVE relevant here?
>
> #ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
>
> struct jump_entry {
> s32 code;
> s32 target;
> long key; // key may be far away from the core kernel under KASLR
> };
Well,... that's odd. I was sure there was a
!HAVE_ARCH_JUMP_LABEL_RELATIVE version somewhere... Oh well.
^ permalink raw reply [flat|nested] 82+ messages in thread
* Re: [PATCH v3 26/64] objtool: Add section/symbol type helpers
2025-06-30 7:29 ` Peter Zijlstra
@ 2025-07-01 19:05 ` Josh Poimboeuf
0 siblings, 0 replies; 82+ messages in thread
From: Josh Poimboeuf @ 2025-07-01 19:05 UTC (permalink / raw)
To: Peter Zijlstra
Cc: x86, linux-kernel, Petr Mladek, Miroslav Benes, Joe Lawrence,
live-patching, Song Liu, laokz, Jiri Kosina,
Marcos Paulo de Souza, Weinan Liu, Fazla Mehrab, Chen Zhongjin,
Puranjay Mohan, Dylan Hatch
On Mon, Jun 30, 2025 at 09:29:38AM +0200, Peter Zijlstra wrote:
> On Fri, Jun 27, 2025 at 09:36:08AM -0700, Josh Poimboeuf wrote:
> > On Fri, Jun 27, 2025 at 12:29:30PM +0200, Peter Zijlstra wrote:
> > > Naming seems inconsistent, there are:
> > >
> > > sym_has_sec(), sec_changed() and sec_size()
> > >
> > > which have the object first, but then most new ones are:
> > >
> > > is_foo_sym() and is_foo_sec()
> > >
> > > which have the object last.
> >
> > For the "is_()" variants, I read them as:
> >
> > "is a(n) <adjective> <noun>"
> >
> > e.g.:
> >
> > is_undef_sym(): "is an UNDEF symbol"
> > is_file_sym(): "is a FILE symbol"
> > is_string_sec() "is a STRING section"
> >
> > Nerding out on English for a second, many of those adjectives can be
> > read as noun adjuncts, e.g. "chicken soup", where a noun functions as an
> > adjective.
> >
> > If we changed those to:
> >
> > "is <noun> <adjective>?"
> >
> > or
> >
> > "is <noun> a <noun>?"
> >
> > then it doesn't always read correctly:
> >
> > is_sym_file(): "is symbol a file?"
> > is_sec_string(): "is section a string?"
>
> English aside; things like sym_*() create a clear namespace, and
> sym_is_file() can be easily read as sym::is_file().
A namespace isn't necessarily a good thing if it hurts readability. A
file symbol is not a file. A string section is not a string. A rela
section is not a relocation.
It makes the code less readable because the natural English reading
("section is a string") doesn't make logical sense, so it takes longer
for the brain to parse.
--
Josh
^ permalink raw reply [flat|nested] 82+ messages in thread
end of thread, other threads:[~2025-07-01 19:05 UTC | newest]
Thread overview: 82+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-06-26 23:54 [PATCH v3 00/64] objtool,livepatch: klp-build livepatch module generation Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 01/64] s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text Josh Poimboeuf
2025-06-27 9:34 ` Heiko Carstens
2025-06-26 23:54 ` [PATCH v3 02/64] vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 03/64] x86/module: Improve relocation error messages Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 04/64] x86/kprobes: Remove STACK_FRAME_NON_STANDARD annotation Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 05/64] compiler: Tweak __UNIQUE_ID() naming Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 06/64] compiler.h: Make addressable symbols less of an eyesore Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 07/64] elfnote: Change ELFNOTE() to use __UNIQUE_ID() Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 08/64] kbuild: Remove 'kmod_' prefix from __KBUILD_MODNAME Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 09/64] modpost: Ignore unresolved section bounds symbols Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 10/64] x86/alternative: Refactor INT3 call emulation selftest Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 11/64] objtool: Make find_symbol_containing() less arbitrary Josh Poimboeuf
2025-06-26 23:54 ` [PATCH v3 12/64] objtool: Fix broken error handling in read_symbols() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 13/64] objtool: Propagate elf_truncate_section() error in elf_write() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 14/64] objtool: Remove error handling boilerplate Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 15/64] objtool: Add empty symbols to the symbol tree again Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 16/64] objtool: Fix interval tree insertion for zero-length symbols Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 17/64] objtool: Fix weak symbol detection Josh Poimboeuf
2025-06-27 9:13 ` Peter Zijlstra
2025-06-27 15:42 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 18/64] objtool: Fix x86 addend calculation Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 19/64] objtool: Fix __pa_symbol() relocation handling Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 20/64] objtool: Fix "unexpected end of section" warning for alternatives Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 21/64] objtool: Check for missing annotation entries in read_annotate() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 22/64] objtool: Const string cleanup Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 23/64] objtool: Clean up compiler flag usage Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 24/64] objtool: Remove .parainstructions reference Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 25/64] objtool: Convert elf iterator macros to use 'struct elf' Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 26/64] objtool: Add section/symbol type helpers Josh Poimboeuf
2025-06-27 10:29 ` Peter Zijlstra
2025-06-27 16:36 ` Josh Poimboeuf
2025-06-30 7:29 ` Peter Zijlstra
2025-07-01 19:05 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 27/64] objtool: Mark .cold subfunctions Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 28/64] objtool: Fix weak symbol hole detection for .cold functions Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 29/64] objtool: Mark prefix functions Josh Poimboeuf
2025-06-27 10:31 ` Peter Zijlstra
2025-06-27 16:53 ` Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 30/64] objtool: Simplify reloc offset calculation in unwind_read_hints() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 31/64] objtool: Avoid emptying lists for duplicate sections Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 32/64] objtool: Rename --Werror to --werror Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 33/64] objtool: Resurrect --backup option Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 34/64] objtool: Reindent check_options[] Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 35/64] objtool: Refactor add_jump_destinations() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 36/64] objtool: Simplify special symbol handling in elf_update_symbol() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 37/64] objtool: Generalize elf_create_symbol() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 38/64] objtool: Generalize elf_create_section() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 39/64] objtool: Add elf_create_data() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 40/64] objtool: Add elf_create_reloc() and elf_init_reloc() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 41/64] objtool: Add elf_create_file() Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 42/64] kbuild,x86: Fix special section module permissions Josh Poimboeuf
2025-06-27 10:53 ` Peter Zijlstra
2025-06-27 17:34 ` Josh Poimboeuf
2025-06-30 7:31 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 43/64] x86/alternative: Define ELF section entry size for alternatives Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels Josh Poimboeuf
2025-06-27 10:48 ` Peter Zijlstra
2025-06-27 16:55 ` Josh Poimboeuf
2025-06-30 7:35 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 45/64] x86/static_call: Define ELF section entry size of static calls Josh Poimboeuf
2025-06-27 10:51 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 46/64] x86/extable: Define ELF section entry size for exception table Josh Poimboeuf
2025-06-27 10:52 ` Peter Zijlstra
2025-06-26 23:55 ` [PATCH v3 47/64] x86/bug: Define ELF section entry size for bug table Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 48/64] x86/orc: Define ELF section entry size for unwind hints Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 49/64] objtool: Unify STACK_FRAME_NON_STANDARD entry sizes Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 50/64] objtool/klp: Add --checksum option to generate per-function checksums Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 51/64] objtool/klp: Add --debug-checksum=<funcs> to show per-instruction checksums Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 52/64] objtool/klp: Introduce klp diff subcommand for diffing object files Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 53/64] objtool/klp: Add --debug option to show cloning decisions Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 54/64] objtool/klp: Add post-link subcommand to finalize livepatch modules Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 55/64] objtool: Disallow duplicate prefix symbols Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 56/64] objtool: Add base objtool support for livepatch modules Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 57/64] livepatch: Add CONFIG_KLP_BUILD Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 58/64] kbuild,objtool: Defer objtool validation step for CONFIG_KLP_BUILD Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 59/64] livepatch/klp-build: Introduce fix-patch-lines script to avoid __LINE__ diff noise Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 60/64] livepatch/klp-build: Add stub init code for livepatch modules Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 61/64] livepatch/klp-build: Introduce klp-build script for generating " Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 62/64] livepatch/klp-build: Add --debug option to show cloning decisions Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 63/64] livepatch/klp-build: Add --show-first-changed option to show function divergence Josh Poimboeuf
2025-06-26 23:55 ` [PATCH v3 64/64] livepatch: Introduce source code helpers for livepatch modules Josh Poimboeuf
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