[RFC PATCH v3 04/22] objtool: Reorganize Unwind hint code

madvenka
2023-02-02T07:42:45Z

From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>

Unwind hint macros and struct unwind_hint are arch-specific. Move them
into the arch-specific file asm/unwind_hints.h. But the unwind hint
types are generic. Retain them in linux/objtool.h.

Unwind hints can be used with static stack validation as well as other
forms of validation such as dynamic FP validation. Move the function
read_unwind_hints() from check.c to a new file unwind_hints.c so that
it can be shared across validation schemes.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
---
arch/x86/include/asm/unwind_hints.h | 83 ++++++++++++
arch/x86/kernel/unwind_orc.c | 2 +-
include/linux/objtool.h | 67 ---------
tools/arch/x86/include/asm/unwind_hints.h | 157 ++++++++++++++++++++++
tools/include/linux/objtool.h | 67 ---------
tools/objtool/Build | 1 +
tools/objtool/check.c | 96 -------------
tools/objtool/include/objtool/insn.h | 1 +
tools/objtool/sync-check.sh | 1 +
tools/objtool/unwind_hints.c | 106 +++++++++++++++
10 files changed, 350 insertions(+), 231 deletions(-)
create mode 100644 tools/arch/x86/include/asm/unwind_hints.h
create mode 100644 tools/objtool/unwind_hints.c

diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index f66fbe6537dd..07c8d911266c 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -1,10 +1,93 @@
#ifndef _ASM_X86_UNWIND_HINTS_H
#define _ASM_X86_UNWIND_HINTS_H

+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+
+/*
+ * This struct is used by asm and inline asm code to manually annotate the
+ * location of registers on the stack.
+ */
+struct unwind_hint {
+ u32 ip;
+ s16 sp_offset;
+ u8 sp_reg;
+ u8 type;
+ u8 end;
+};
+#endif
+
#include <linux/objtool.h>

#include "orc_types.h"

+#ifdef CONFIG_OBJTOOL
+
+#ifndef __ASSEMBLY__
+
+#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
+ "987: \n\t" \
+ ".pushsection .discard.unwind_hints\n\t" \
+ /* struct unwind_hint */ \
+ ".long 987b - .\n\t" \
+ ".short " __stringify(sp_offset) "\n\t" \
+ ".byte " __stringify(sp_reg) "\n\t" \
+ ".byte " __stringify(type) "\n\t" \
+ ".byte " __stringify(end) "\n\t" \
+ ".balign 4 \n\t" \
+ ".popsection\n\t"
+
+#else /* __ASSEMBLY__ */
+
+/*
+ * In asm, there are two kinds of code: normal C-type callable functions and
+ * the rest. The normal callable functions can be called by other code, and
+ * don't do anything unusual with the stack. Such normal callable functions
+ * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
+ * category. In this case, no special debugging annotations are needed because
+ * objtool can automatically generate the ORC data for the ORC unwinder to read
+ * at runtime.
+ *
+ * Anything which doesn't fall into the above category, such as syscall and
+ * interrupt handlers, tends to not be called directly by other functions, and
+ * often does unusual non-C-function-type things with the stack pointer. Such
+ * code needs to be annotated such that objtool can understand it. The
+ * following CFI hint macros are for this type of code.
+ *
+ * These macros provide hints to objtool about the state of the stack at each
+ * instruction. Objtool starts from the hints and follows the code flow,
+ * making automatic CFI adjustments when it sees pushes and pops, filling out
+ * the debuginfo as necessary. It will also warn if it sees any
+ * inconsistencies.
+ */
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.Lunwind_hint_ip_\@:
+ .pushsection .discard.unwind_hints
+ /* struct unwind_hint */
+ .long .Lunwind_hint_ip_\@ - .
+ .short \sp_offset
+ .byte \sp_reg
+ .byte \type
+ .byte \end
+ .balign 4
+ .popsection
+.endm
+
+#endif /* __ASSEMBLY__ */
+
+#else /* !CONFIG_OBJTOOL */
+
+#ifndef __ASSEMBLY__
+#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
+ "\n\t"
+#else
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.endm
+#endif
+
+#endif /* CONFIG_OBJTOOL */
+
#ifdef __ASSEMBLY__

.macro UNWIND_HINT_EMPTY
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index c059820dfaea..c2bfc597d909 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -1,10 +1,10 @@
// SPDX-License-Identifier: GPL-2.0-only
-#include <linux/objtool.h>
#include <linux/module.h>
#include <linux/sort.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
+#include <asm/unwind_hints.h>
#include <asm/orc_types.h>
#include <asm/orc_lookup.h>

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 62c54ffbeeaa..1af295efc12c 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -2,23 +2,6 @@
#ifndef _LINUX_OBJTOOL_H
#define _LINUX_OBJTOOL_H

-#ifndef __ASSEMBLY__
-
-#include <linux/types.h>
-
-/*
- * This struct is used by asm and inline asm code to manually annotate the
- * location of registers on the stack.
- */
-struct unwind_hint {
- u32 ip;
- s16 sp_offset;
- u8 sp_reg;
- u8 type;
- u8 end;
-};
-#endif
-
/*
* UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
* (the caller's SP right before it made the call). Used for all callable
@@ -49,18 +32,6 @@ struct unwind_hint {

#ifndef __ASSEMBLY__

-#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
- "987: \n\t" \
- ".pushsection .discard.unwind_hints\n\t" \
- /* struct unwind_hint */ \
- ".long 987b - .\n\t" \
- ".short " __stringify(sp_offset) "\n\t" \
- ".byte " __stringify(sp_reg) "\n\t" \
- ".byte " __stringify(type) "\n\t" \
- ".byte " __stringify(end) "\n\t" \
- ".balign 4 \n\t" \
- ".popsection\n\t"
-
/*
* This macro marks the given function's stack frame as "non-standard", which
* tells objtool to ignore the function when doing stack metadata validation.
@@ -108,40 +79,6 @@ struct unwind_hint {
.long 999b; \
.popsection;

-/*
- * In asm, there are two kinds of code: normal C-type callable functions and
- * the rest. The normal callable functions can be called by other code, and
- * don't do anything unusual with the stack. Such normal callable functions
- * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
- * category. In this case, no special debugging annotations are needed because
- * objtool can automatically generate the ORC data for the ORC unwinder to read
- * at runtime.
- *
- * Anything which doesn't fall into the above category, such as syscall and
- * interrupt handlers, tends to not be called directly by other functions, and
- * often does unusual non-C-function-type things with the stack pointer. Such
- * code needs to be annotated such that objtool can understand it. The
- * following CFI hint macros are for this type of code.
- *
- * These macros provide hints to objtool about the state of the stack at each
- * instruction. Objtool starts from the hints and follows the code flow,
- * making automatic CFI adjustments when it sees pushes and pops, filling out
- * the debuginfo as necessary. It will also warn if it sees any
- * inconsistencies.
- */
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
-.Lunwind_hint_ip_\@:
- .pushsection .discard.unwind_hints
- /* struct unwind_hint */
- .long .Lunwind_hint_ip_\@ - .
- .short \sp_offset
- .byte \sp_reg
- .byte \type
- .byte \end
- .balign 4
- .popsection
-.endm
-
.macro STACK_FRAME_NON_STANDARD func:req
.pushsection .discard.func_stack_frame_non_standard, "aw"
_ASM_PTR \func
@@ -174,16 +111,12 @@ struct unwind_hint {

#ifndef __ASSEMBLY__

-#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
- "\n\t"
#define STACK_FRAME_NON_STANDARD(func)
#define STACK_FRAME_NON_STANDARD_FP(func)
#define ANNOTATE_NOENDBR
#define ASM_REACHABLE
#else
#define ANNOTATE_INTRA_FUNCTION_CALL
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
-.endm
.macro STACK_FRAME_NON_STANDARD func:req
.endm
.macro ANNOTATE_NOENDBR
diff --git a/tools/arch/x86/include/asm/unwind_hints.h b/tools/arch/x86/include/asm/unwind_hints.h
new file mode 100644
index 000000000000..07c8d911266c
--- /dev/null
+++ b/tools/arch/x86/include/asm/unwind_hints.h
@@ -0,0 +1,157 @@
+#ifndef _ASM_X86_UNWIND_HINTS_H
+#define _ASM_X86_UNWIND_HINTS_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+
+/*
+ * This struct is used by asm and inline asm code to manually annotate the
+ * location of registers on the stack.
+ */
+struct unwind_hint {
+ u32 ip;
+ s16 sp_offset;
+ u8 sp_reg;
+ u8 type;
+ u8 end;
+};
+#endif
+
+#include <linux/objtool.h>
+
+#include "orc_types.h"
+
+#ifdef CONFIG_OBJTOOL
+
+#ifndef __ASSEMBLY__
+
+#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
+ "987: \n\t" \
+ ".pushsection .discard.unwind_hints\n\t" \
+ /* struct unwind_hint */ \
+ ".long 987b - .\n\t" \
+ ".short " __stringify(sp_offset) "\n\t" \
+ ".byte " __stringify(sp_reg) "\n\t" \
+ ".byte " __stringify(type) "\n\t" \
+ ".byte " __stringify(end) "\n\t" \
+ ".balign 4 \n\t" \
+ ".popsection\n\t"
+
+#else /* __ASSEMBLY__ */
+
+/*
+ * In asm, there are two kinds of code: normal C-type callable functions and
+ * the rest. The normal callable functions can be called by other code, and
+ * don't do anything unusual with the stack. Such normal callable functions
+ * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
+ * category. In this case, no special debugging annotations are needed because
+ * objtool can automatically generate the ORC data for the ORC unwinder to read
+ * at runtime.
+ *
+ * Anything which doesn't fall into the above category, such as syscall and
+ * interrupt handlers, tends to not be called directly by other functions, and
+ * often does unusual non-C-function-type things with the stack pointer. Such
+ * code needs to be annotated such that objtool can understand it. The
+ * following CFI hint macros are for this type of code.
+ *
+ * These macros provide hints to objtool about the state of the stack at each
+ * instruction. Objtool starts from the hints and follows the code flow,
+ * making automatic CFI adjustments when it sees pushes and pops, filling out
+ * the debuginfo as necessary. It will also warn if it sees any
+ * inconsistencies.
+ */
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.Lunwind_hint_ip_\@:
+ .pushsection .discard.unwind_hints
+ /* struct unwind_hint */
+ .long .Lunwind_hint_ip_\@ - .
+ .short \sp_offset
+ .byte \sp_reg
+ .byte \type
+ .byte \end
+ .balign 4
+ .popsection
+.endm
+
+#endif /* __ASSEMBLY__ */
+
+#else /* !CONFIG_OBJTOOL */
+
+#ifndef __ASSEMBLY__
+#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
+ "\n\t"
+#else
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.endm
+#endif
+
+#endif /* CONFIG_OBJTOOL */
+
+#ifdef __ASSEMBLY__
+
+.macro UNWIND_HINT_EMPTY
+ UNWIND_HINT type=UNWIND_HINT_TYPE_CALL end=1
+.endm
+
+.macro UNWIND_HINT_ENTRY
+ UNWIND_HINT type=UNWIND_HINT_TYPE_ENTRY end=1
+.endm
+
+.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 partial=0
+ .if \base == %rsp
+ .if \indirect
+ .set sp_reg, ORC_REG_SP_INDIRECT
+ .else
+ .set sp_reg, ORC_REG_SP
+ .endif
+ .elseif \base == %rbp
+ .set sp_reg, ORC_REG_BP
+ .elseif \base == %rdi
+ .set sp_reg, ORC_REG_DI
+ .elseif \base == %rdx
+ .set sp_reg, ORC_REG_DX
+ .elseif \base == %r10
+ .set sp_reg, ORC_REG_R10
+ .else
+ .error "UNWIND_HINT_REGS: bad base register"
+ .endif
+
+ .set sp_offset, \offset
+
+ .if \partial
+ .set type, UNWIND_HINT_TYPE_REGS_PARTIAL
+ .elseif \extra == 0
+ .set type, UNWIND_HINT_TYPE_REGS_PARTIAL
+ .set sp_offset, \offset + (16*8)
+ .else
+ .set type, UNWIND_HINT_TYPE_REGS
+ .endif
+
+ UNWIND_HINT sp_reg=sp_reg sp_offset=sp_offset type=type
+.endm
+
+.macro UNWIND_HINT_IRET_REGS base=%rsp offset=0
+ UNWIND_HINT_REGS base=\base offset=\offset partial=1
+.endm
+
+.macro UNWIND_HINT_FUNC
+ UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=8 type=UNWIND_HINT_TYPE_FUNC
+.endm
+
+.macro UNWIND_HINT_SAVE
+ UNWIND_HINT type=UNWIND_HINT_TYPE_SAVE
+.endm
+
+.macro UNWIND_HINT_RESTORE
+ UNWIND_HINT type=UNWIND_HINT_TYPE_RESTORE
+.endm
+
+#else
+
+#define UNWIND_HINT_FUNC \
+ UNWIND_HINT(ORC_REG_SP, 8, UNWIND_HINT_TYPE_FUNC, 0)
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_UNWIND_HINTS_H */
diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h
index 62c54ffbeeaa..1af295efc12c 100644
--- a/tools/include/linux/objtool.h
+++ b/tools/include/linux/objtool.h
@@ -2,23 +2,6 @@
#ifndef _LINUX_OBJTOOL_H
#define _LINUX_OBJTOOL_H

-#ifndef __ASSEMBLY__
-
-#include <linux/types.h>
-
-/*
- * This struct is used by asm and inline asm code to manually annotate the
- * location of registers on the stack.
- */
-struct unwind_hint {
- u32 ip;
- s16 sp_offset;
- u8 sp_reg;
- u8 type;
- u8 end;
-};
-#endif
-
/*
* UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
* (the caller's SP right before it made the call). Used for all callable
@@ -49,18 +32,6 @@ struct unwind_hint {

#ifndef __ASSEMBLY__

-#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
- "987: \n\t" \
- ".pushsection .discard.unwind_hints\n\t" \
- /* struct unwind_hint */ \
- ".long 987b - .\n\t" \
- ".short " __stringify(sp_offset) "\n\t" \
- ".byte " __stringify(sp_reg) "\n\t" \
- ".byte " __stringify(type) "\n\t" \
- ".byte " __stringify(end) "\n\t" \
- ".balign 4 \n\t" \
- ".popsection\n\t"
-
/*
* This macro marks the given function's stack frame as "non-standard", which
* tells objtool to ignore the function when doing stack metadata validation.
@@ -108,40 +79,6 @@ struct unwind_hint {
.long 999b; \
.popsection;

-/*
- * In asm, there are two kinds of code: normal C-type callable functions and
- * the rest. The normal callable functions can be called by other code, and
- * don't do anything unusual with the stack. Such normal callable functions
- * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
- * category. In this case, no special debugging annotations are needed because
- * objtool can automatically generate the ORC data for the ORC unwinder to read
- * at runtime.
- *
- * Anything which doesn't fall into the above category, such as syscall and
- * interrupt handlers, tends to not be called directly by other functions, and
- * often does unusual non-C-function-type things with the stack pointer. Such
- * code needs to be annotated such that objtool can understand it. The
- * following CFI hint macros are for this type of code.
- *
- * These macros provide hints to objtool about the state of the stack at each
- * instruction. Objtool starts from the hints and follows the code flow,
- * making automatic CFI adjustments when it sees pushes and pops, filling out
- * the debuginfo as necessary. It will also warn if it sees any
- * inconsistencies.
- */
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
-.Lunwind_hint_ip_\@:
- .pushsection .discard.unwind_hints
- /* struct unwind_hint */
- .long .Lunwind_hint_ip_\@ - .
- .short \sp_offset
- .byte \sp_reg
- .byte \type
- .byte \end
- .balign 4
- .popsection
-.endm
-
.macro STACK_FRAME_NON_STANDARD func:req
.pushsection .discard.func_stack_frame_non_standard, "aw"
_ASM_PTR \func
@@ -174,16 +111,12 @@ struct unwind_hint {

#ifndef __ASSEMBLY__

-#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
- "\n\t"
#define STACK_FRAME_NON_STANDARD(func)
#define STACK_FRAME_NON_STANDARD_FP(func)
#define ANNOTATE_NOENDBR
#define ASM_REACHABLE
#else
#define ANNOTATE_INTRA_FUNCTION_CALL
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
-.endm
.macro STACK_FRAME_NON_STANDARD func:req
.endm
.macro ANNOTATE_NOENDBR
diff --git a/tools/objtool/Build b/tools/objtool/Build
index 8afe56cd0c2d..c4666d0b40ba 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -8,6 +8,7 @@ objtool-y += builtin-check.o
objtool-y += cfi.o
objtool-y += insn.o
objtool-y += decode.o
+objtool-y += unwind_hints.o
objtool-y += elf.o
objtool-y += objtool.o

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index be3f6564104a..d14a2b7b8b37 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1670,102 +1670,6 @@ static int add_jump_table_alts(struct objtool_file *file)
return 0;
}

-static int read_unwind_hints(struct objtool_file *file)
-{
- struct cfi_state cfi = init_cfi;
- struct section *sec, *relocsec;
- struct unwind_hint *hint;
- struct instruction *insn;
- struct reloc *reloc;
- int i;
-
- sec = find_section_by_name(file->elf, ".discard.unwind_hints");
- if (!sec)
- return 0;
-
- relocsec = sec->reloc;
- if (!relocsec) {
- WARN("missing .rela.discard.unwind_hints section");
- return -1;
- }
-
- if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
- WARN("struct unwind_hint size mismatch");
- return -1;
- }
-
- file->hints = true;
-
- for (i = 0; i < sec->sh.sh_size / 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));
- if (!reloc) {
- WARN("can't find reloc for unwind_hints[%d]", i);
- return -1;
- }
-
- insn = find_insn(file, reloc->sym->sec, reloc->addend);
- if (!insn) {
- WARN("can't find insn for unwind_hints[%d]", i);
- return -1;
- }
-
- insn->hint = true;
-
- if (hint->type == UNWIND_HINT_TYPE_SAVE) {
- insn->hint = false;
- insn->save = true;
- continue;
- }
-
- if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
- insn->restore = true;
- continue;
- }
-
- 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 (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
- WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
- insn->sec, insn->offset);
- }
-
- insn->entry = 1;
- }
- }
-
- if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
- hint->type = UNWIND_HINT_TYPE_CALL;
- insn->entry = 1;
- }
-
- if (hint->type == UNWIND_HINT_TYPE_FUNC) {
- insn->cfi = &func_cfi;
- continue;
- }
-
- if (insn->cfi)
- cfi = *(insn->cfi);
-
- if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
- WARN_FUNC("unsupported unwind_hint sp base reg %d",
- insn->sec, insn->offset, hint->sp_reg);
- return -1;
- }
-
- cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
- cfi.type = hint->type;
- cfi.end = hint->end;
-
- insn->cfi = cfi_hash_find_or_add(&cfi);
- }
-
- return 0;
-}
-
static int read_noendbr_hints(struct objtool_file *file)
{
struct section *sec;
diff --git a/tools/objtool/include/objtool/insn.h b/tools/objtool/include/objtool/insn.h
index b74c7f0d9076..cfd1ae7e2e8e 100644
--- a/tools/objtool/include/objtool/insn.h
+++ b/tools/objtool/include/objtool/insn.h
@@ -89,6 +89,7 @@ bool same_function(struct instruction *insn1, struct instruction *insn2);
bool is_first_func_insn(struct objtool_file *file, struct instruction *insn);

int decode_instructions(struct objtool_file *file);
+int read_unwind_hints(struct objtool_file *file);

#define for_each_insn(file, insn) \
list_for_each_entry(insn, &file->insn_list, list)
diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
index 105a291ff8e7..ee49b4e9e72c 100755
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -14,6 +14,7 @@ arch/x86/include/asm/nops.h
arch/x86/include/asm/inat_types.h
arch/x86/include/asm/orc_types.h
arch/x86/include/asm/emulate_prefix.h
+arch/x86/include/asm/unwind_hints.h
arch/x86/lib/x86-opcode-map.txt
arch/x86/tools/gen-insn-attr-x86.awk
include/linux/static_call_types.h
diff --git a/tools/objtool/unwind_hints.c b/tools/objtool/unwind_hints.c
new file mode 100644
index 000000000000..f2521659bae5
--- /dev/null
+++ b/tools/objtool/unwind_hints.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+#include <asm/unwind_hints.h>
+
+#include <objtool/builtin.h>
+#include <objtool/endianness.h>
+#include <objtool/insn.h>
+#include <objtool/warn.h>
+
+int read_unwind_hints(struct objtool_file *file)
+{
+ struct cfi_state cfi = init_cfi;
+ struct section *sec, *relocsec;
+ struct unwind_hint *hint;
+ struct instruction *insn;
+ struct reloc *reloc;
+ int i;
+
+ sec = find_section_by_name(file->elf, ".discard.unwind_hints");
+ if (!sec)
+ return 0;
+
+ relocsec = sec->reloc;
+ if (!relocsec) {
+ WARN("missing .rela.discard.unwind_hints section");
+ return -1;
+ }
+
+ if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
+ WARN("struct unwind_hint size mismatch");
+ return -1;
+ }
+
+ file->hints = true;
+
+ for (i = 0; i < sec->sh.sh_size / 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));
+ if (!reloc) {
+ WARN("can't find reloc for unwind_hints[%d]", i);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc->addend);
+ if (!insn) {
+ WARN("can't find insn for unwind_hints[%d]", i);
+ return -1;
+ }
+
+ insn->hint = true;
+
+ if (hint->type == UNWIND_HINT_TYPE_SAVE) {
+ insn->hint = false;
+ insn->save = true;
+ continue;
+ }
+
+ if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
+ insn->restore = true;
+ continue;
+ }
+
+ 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 (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
+ WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
+ insn->sec, insn->offset);
+ }
+
+ insn->entry = 1;
+ }
+ }
+
+ if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
+ hint->type = UNWIND_HINT_TYPE_CALL;
+ insn->entry = 1;
+ }
+
+ if (hint->type == UNWIND_HINT_TYPE_FUNC) {
+ insn->cfi = &func_cfi;
+ continue;
+ }
+
+ if (insn->cfi)
+ cfi = *(insn->cfi);
+
+ if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
+ WARN_FUNC("unsupported unwind_hint sp base reg %d",
+ insn->sec, insn->offset, hint->sp_reg);
+ return -1;
+ }
+
+ cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
+ cfi.type = hint->type;
+ cfi.end = hint->end;
+
+ insn->cfi = cfi_hash_find_or_add(&cfi);
+ }
+
+ return 0;
+}
--
2.25.1