* [PATCH v5 0/8] unwind, arm64: add sframe unwinder for kernel
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
Implement a generic kernel sframe-based [1] unwinder. The main goal is
to improve reliable stacktrace on arm64 by unwinding across exception
boundaries.
On x86, the ORC unwinder provides reliable stacktrace through similar
methodology, but arm64 lacks the necessary support from objtool to
create ORC unwind tables.
Currently, there's already a sframe unwinder proposed for userspace: [2].
To maintain common definitions and algorithms for sframe lookup, a
substantial portion of this patch series aims to refactor the sframe
lookup code to support both kernel and userspace sframe sections.
Currently, only GNU Binutils support sframe. This series relies on the
Sframe V3 format, which is supported in binutils 2.46.
These patches are based on Steven Rostedt's sframe/core branch [3],
which is and aggregation of existing work done for x86 sframe userspace
unwind, and contains [2]. This branch is, in turn, based on Linux
v7.0-rc3. This full series (applied to the sframe/core branch) is
available on github: [4].
Ref:
[1]: https://sourceware.org/binutils/docs/sframe-spec.html
[2]: https://lore.kernel.org/lkml/20260127150554.2760964-1-jremus@linux.ibm.com/
[3]: https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git/log/?h=sframe/core
[4]: https://github.com/dylanbhatch/linux/tree/sframe-v5
Changes since v4:
- (Jens) Fix some minor nits.
- Handle .init.text and .exit.text in function address validation.
Changes since v3:
- (Jens) Clean up patch summaries.
- (Jens) Rename SFRAME_LOOKUP -> UNWIND_SFRAME_LOOKUP to fit existing
naming convention.
- (Randy) Correct typo errors in new config options.
- (Jens) Move unwind types to a new unwind_types.h to match their
usage.
- (Jens) Update KERNEL_[COPY|GET] to use label-based error handling
like their userspace counterparts.
- (Jens) Rename SFRAME_UNWINDER -> HAVE_UNWIND_KERNEL_SFRAME and
ARCH_SUPPORTS_SFRAME_UNWINDER -> ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
to match existing naming convention.
- (Jens) Move HAVE_UNWIND_KERNEL_SFRAME config option to arch/Kconfig.
- (Jens) Rename/move extern definitions of __[start|end]_sframe into
include/asm-generic/sections.h.
- (Jens) Fix up CFI annotations at kernel entry.
- (Jens) Fix error path for unsorted FDE lookup.
- (Jens) Zero-out module sframe_section before init.
- (Jens) For SFRAME_VALIDATION, use an arch-specific function-address
validation helper so that .rodata.text can be correctly handled on
arm64 vmlinux.
- (Jens) Fixup and better comment kernel stacktrace code.
Changes since v2:
The biggest change from v2 is the switch from adding a dedicated,
in-kernel sframe-lookup library, to refactoring/using the existing
library developed by Josh, Jens, and Steve. Consequently, this series
now depends on Sframe V3, though this upgrade would likely have been
necessary anyway. Below is a full accounting of the changes since v2.
- (Josh) Add stricter reliability checks during unwind.
- (Puranjay, Indu, Jens) Update to use a common sframe library with
userpace unwind, thus resolving the need to support
SFRAME_F_FDE_FUNC_START_PCREL, added in binutils 2.45.
- (Jens) Add check for sframe V3, thus resolving the prior need for V2
and SFRAME_F_FDE_FUNC_START_PCREL support.
- (Will) Add ARCH_SUPPORTS_SFRAME_UNWINDER, remove SFRAME_UNWIND_TABLE
- (Indu) add support for unsorted FDE tables, allowing for module
sframe lookups.
- (Mark) Prefer frame-pointer unwind when possible, for better
performance.
- Simplify compile-time logic, adding stubbs when necessary.
- Add support for in-kernel SFRAME_VALIDATION.
- Rebase onto core/sframe (with v7.0-rc3 base)
Dylan Hatch (7):
sframe: Allow kernelspace sframe sections
arm64, unwind: build kernel with sframe V3 info
sframe: Provide PC lookup for vmlinux .sframe section
sframe: Allow unsorted FDEs
arm64/module, sframe: Add sframe support for modules
sframe: Introduce in-kernel SFRAME_VALIDATION
unwind: arm64: Use sframe to unwind interrupt frames
Weinan Liu (1):
arm64: entry: add unwind info for various kernel entries
MAINTAINERS | 3 +-
Makefile | 8 +
arch/Kconfig | 27 +-
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/module.h | 6 +
arch/arm64/include/asm/sections.h | 1 +
arch/arm64/include/asm/stacktrace/common.h | 6 +
arch/arm64/include/asm/unwind_sframe.h | 55 +++
arch/arm64/kernel/entry.S | 23 +
arch/arm64/kernel/module.c | 8 +
arch/arm64/kernel/setup.c | 2 +
arch/arm64/kernel/stacktrace.c | 246 ++++++++++-
arch/arm64/kernel/vdso/Makefile | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 2 +
.../{unwind_user_sframe.h => unwind_sframe.h} | 6 +-
arch/x86/include/asm/unwind_user.h | 12 +-
include/asm-generic/sections.h | 4 +
include/asm-generic/vmlinux.lds.h | 15 +
include/linux/sframe.h | 67 ++-
include/linux/unwind_types.h | 46 ++
include/linux/unwind_user_types.h | 41 --
kernel/unwind/Makefile | 2 +-
kernel/unwind/sframe.c | 410 ++++++++++++++----
kernel/unwind/user.c | 41 +-
24 files changed, 827 insertions(+), 207 deletions(-)
create mode 100644 arch/arm64/include/asm/unwind_sframe.h
rename arch/x86/include/asm/{unwind_user_sframe.h => unwind_sframe.h} (50%)
create mode 100644 include/linux/unwind_types.h
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply
* [PATCH v5 1/8] sframe: Allow kernelspace sframe sections
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
Generalize the sframe lookup code to support kernelspace sections. This
is done by defining a SFRAME_LOOKUP option that can be activated
separate from HAVE_UNWIND_USER_SFRAME, as there will be other client to
this library than just userspace unwind.
Sframe section location is now tracked in a separate sec_type field to
determine whether user-access functions are necessary to read the sframe
data. Relevant type delarations are moved and renamed to reflect the
non-user sframe support.
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
MAINTAINERS | 2 +-
arch/Kconfig | 4 +
.../{unwind_user_sframe.h => unwind_sframe.h} | 6 +-
arch/x86/include/asm/unwind_user.h | 12 +-
include/linux/sframe.h | 48 ++--
include/linux/unwind_types.h | 46 +++
include/linux/unwind_user_types.h | 41 ---
kernel/unwind/Makefile | 2 +-
kernel/unwind/sframe.c | 270 ++++++++++++------
kernel/unwind/user.c | 41 +--
10 files changed, 293 insertions(+), 179 deletions(-)
rename arch/x86/include/asm/{unwind_user_sframe.h => unwind_sframe.h} (50%)
create mode 100644 include/linux/unwind_types.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 8c46465ee7a9..cfc7dec88da4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -27557,7 +27557,7 @@ F: Documentation/driver-api/uio-howto.rst
F: drivers/uio/
F: include/linux/uio_driver.h
-USERSPACE STACK UNWINDING
+STACK UNWINDING
M: Josh Poimboeuf <jpoimboe@kernel.org>
M: Steven Rostedt <rostedt@goodmis.org>
S: Maintained
diff --git a/arch/Kconfig b/arch/Kconfig
index f1ed8bc0806d..d7caf2e245ce 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -486,6 +486,9 @@ config AS_SFRAME3
def_bool $(as-instr,.cfi_startproc\n.cfi_endproc,-Wa$(comma)--gsframe-3)
select AS_SFRAME
+config UNWIND_SFRAME_LOOKUP
+ bool
+
config UNWIND_USER
bool
@@ -496,6 +499,7 @@ config HAVE_UNWIND_USER_FP
config HAVE_UNWIND_USER_SFRAME
bool
select UNWIND_USER
+ select UNWIND_SFRAME_LOOKUP
config SFRAME_VALIDATION
bool "Enable .sframe section debugging"
diff --git a/arch/x86/include/asm/unwind_user_sframe.h b/arch/x86/include/asm/unwind_sframe.h
similarity index 50%
rename from arch/x86/include/asm/unwind_user_sframe.h
rename to arch/x86/include/asm/unwind_sframe.h
index d828ae1a4aac..44d42e6ffde4 100644
--- a/arch/x86/include/asm/unwind_user_sframe.h
+++ b/arch/x86/include/asm/unwind_sframe.h
@@ -1,6 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_X86_UNWIND_USER_SFRAME_H
-#define _ASM_X86_UNWIND_USER_SFRAME_H
+#ifndef _ASM_X86_UNWIND_SFRAME_H
+#define _ASM_X86_UNWIND_SFRAME_H
#ifdef CONFIG_X86_64
@@ -9,4 +9,4 @@
#endif
-#endif /* _ASM_X86_UNWIND_USER_SFRAME_H */
+#endif /* _ASM_X86_UNWIND_SFRAME_H */
diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwind_user.h
index ae46906c3b39..8fdab3581b86 100644
--- a/arch/x86/include/asm/unwind_user.h
+++ b/arch/x86/include/asm/unwind_user.h
@@ -55,30 +55,30 @@ static inline int unwind_user_get_reg(unsigned long *val, unsigned int regnum)
#define ARCH_INIT_USER_FP_FRAME(ws) \
.cfa = { \
- .rule = UNWIND_USER_CFA_RULE_FP_OFFSET,\
+ .rule = UNWIND_CFA_RULE_FP_OFFSET,\
.offset = 2*(ws), \
}, \
.ra = { \
- .rule = UNWIND_USER_RULE_CFA_OFFSET_DEREF,\
+ .rule = UNWIND_RULE_CFA_OFFSET_DEREF,\
.offset = -1*(ws), \
}, \
.fp = { \
- .rule = UNWIND_USER_RULE_CFA_OFFSET_DEREF,\
+ .rule = UNWIND_RULE_CFA_OFFSET_DEREF,\
.offset = -2*(ws), \
}, \
.outermost = false,
#define ARCH_INIT_USER_FP_ENTRY_FRAME(ws) \
.cfa = { \
- .rule = UNWIND_USER_CFA_RULE_SP_OFFSET,\
+ .rule = UNWIND_CFA_RULE_SP_OFFSET,\
.offset = 1*(ws), \
}, \
.ra = { \
- .rule = UNWIND_USER_RULE_CFA_OFFSET_DEREF,\
+ .rule = UNWIND_RULE_CFA_OFFSET_DEREF,\
.offset = -1*(ws), \
}, \
.fp = { \
- .rule = UNWIND_USER_RULE_RETAIN,\
+ .rule = UNWIND_RULE_RETAIN,\
}, \
.outermost = false,
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index b79c5ec09229..0cb2924367bc 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -3,37 +3,46 @@
#define _LINUX_SFRAME_H
#include <linux/mm_types.h>
+#include <linux/unwind_types.h>
#include <linux/srcu.h>
-#include <linux/unwind_user_types.h>
-#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME
+#ifdef CONFIG_UNWIND_SFRAME_LOOKUP
+
+enum sframe_sec_type {
+ SFRAME_KERNEL,
+ SFRAME_USER,
+};
struct sframe_section {
- struct rcu_head rcu;
+ struct rcu_head rcu;
#ifdef CONFIG_DYNAMIC_DEBUG
- const char *filename;
+ const char *filename;
#endif
- unsigned long sframe_start;
- unsigned long sframe_end;
- unsigned long text_start;
- unsigned long text_end;
-
- unsigned long fdes_start;
- unsigned long fres_start;
- unsigned long fres_end;
- unsigned int num_fdes;
-
- signed char ra_off;
- signed char fp_off;
+ enum sframe_sec_type sec_type;
+ unsigned long sframe_start;
+ unsigned long sframe_end;
+ unsigned long text_start;
+ unsigned long text_end;
+
+ unsigned long fdes_start;
+ unsigned long fres_start;
+ unsigned long fres_end;
+ unsigned int num_fdes;
+
+ signed char ra_off;
+ signed char fp_off;
};
+#endif /* CONFIG_UNWIND_SFRAME_LOOKUP */
+
+#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME
+
#define INIT_MM_SFRAME .sframe_mt = MTREE_INIT(sframe_mt, 0),
extern void sframe_free_mm(struct mm_struct *mm);
extern int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end,
unsigned long text_start, unsigned long text_end);
extern int sframe_remove_section(unsigned long sframe_addr);
-extern int sframe_find(unsigned long ip, struct unwind_user_frame *frame);
static inline bool current_has_sframe(void)
{
@@ -42,6 +51,8 @@ static inline bool current_has_sframe(void)
return mm && !mtree_empty(&mm->sframe_mt);
}
+extern int sframe_find_user(unsigned long ip, struct unwind_frame *frame);
+
#else /* !CONFIG_HAVE_UNWIND_USER_SFRAME */
#define INIT_MM_SFRAME
@@ -52,9 +63,10 @@ static inline int sframe_add_section(unsigned long sframe_start, unsigned long s
return -ENOSYS;
}
static inline int sframe_remove_section(unsigned long sframe_addr) { return -ENOSYS; }
-static inline int sframe_find(unsigned long ip, struct unwind_user_frame *frame) { return -ENOSYS; }
static inline bool current_has_sframe(void) { return false; }
+static inline int sframe_find_user(unsigned long ip, struct unwind_frame *frame) { return -ENOSYS; }
+
#endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */
#endif /* _LINUX_SFRAME_H */
diff --git a/include/linux/unwind_types.h b/include/linux/unwind_types.h
new file mode 100644
index 000000000000..08bcb0aa04aa
--- /dev/null
+++ b/include/linux/unwind_types.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_UNWIND_TYPES_H
+#define _LINUX_UNWIND_TYPES_H
+
+#define UNWIND_RULE_DEREF BIT(31)
+
+enum unwind_cfa_rule {
+ UNWIND_CFA_RULE_SP_OFFSET, /* CFA = SP + offset */
+ UNWIND_CFA_RULE_FP_OFFSET, /* CFA = FP + offset */
+ UNWIND_CFA_RULE_REG_OFFSET, /* CFA = reg + offset */
+ /* DEREF variants */
+ UNWIND_CFA_RULE_REG_OFFSET_DEREF = /* CFA = *(reg + offset) */
+ UNWIND_CFA_RULE_REG_OFFSET | UNWIND_RULE_DEREF,
+};
+
+struct unwind_cfa_rule_data {
+ enum unwind_cfa_rule rule;
+ s32 offset;
+ unsigned int regnum;
+};
+
+enum unwind_rule {
+ UNWIND_RULE_RETAIN, /* entity = entity */
+ UNWIND_RULE_CFA_OFFSET, /* entity = CFA + offset */
+ UNWIND_RULE_REG_OFFSET, /* entity = register + offset */
+ /* DEREF variants */
+ UNWIND_RULE_CFA_OFFSET_DEREF = /* entity = *(CFA + offset) */
+ UNWIND_RULE_CFA_OFFSET | UNWIND_RULE_DEREF,
+ UNWIND_RULE_REG_OFFSET_DEREF = /* entity = *(register + offset) */
+ UNWIND_RULE_REG_OFFSET | UNWIND_RULE_DEREF,
+};
+
+struct unwind_rule_data {
+ enum unwind_rule rule;
+ s32 offset;
+ unsigned int regnum;
+};
+
+struct unwind_frame {
+ struct unwind_cfa_rule_data cfa;
+ struct unwind_rule_data ra;
+ struct unwind_rule_data fp;
+ bool outermost;
+};
+
+#endif /* _LINUX_UNWIND_TYPES_H */
diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_types.h
index 059e5c76f2f3..646e5fb774db 100644
--- a/include/linux/unwind_user_types.h
+++ b/include/linux/unwind_user_types.h
@@ -27,47 +27,6 @@ struct unwind_stacktrace {
unsigned long *entries;
};
-#define UNWIND_USER_RULE_DEREF BIT(31)
-
-enum unwind_user_cfa_rule {
- UNWIND_USER_CFA_RULE_SP_OFFSET, /* CFA = SP + offset */
- UNWIND_USER_CFA_RULE_FP_OFFSET, /* CFA = FP + offset */
- UNWIND_USER_CFA_RULE_REG_OFFSET, /* CFA = reg + offset */
- /* DEREF variants */
- UNWIND_USER_CFA_RULE_REG_OFFSET_DEREF = /* CFA = *(reg + offset) */
- UNWIND_USER_CFA_RULE_REG_OFFSET | UNWIND_USER_RULE_DEREF,
-};
-
-struct unwind_user_cfa_rule_data {
- enum unwind_user_cfa_rule rule;
- s32 offset;
- unsigned int regnum;
-};
-
-enum unwind_user_rule {
- UNWIND_USER_RULE_RETAIN, /* entity = entity */
- UNWIND_USER_RULE_CFA_OFFSET, /* entity = CFA + offset */
- UNWIND_USER_RULE_REG_OFFSET, /* entity = register + offset */
- /* DEREF variants */
- UNWIND_USER_RULE_CFA_OFFSET_DEREF = /* entity = *(CFA + offset) */
- UNWIND_USER_RULE_CFA_OFFSET | UNWIND_USER_RULE_DEREF,
- UNWIND_USER_RULE_REG_OFFSET_DEREF = /* entity = *(register + offset) */
- UNWIND_USER_RULE_REG_OFFSET | UNWIND_USER_RULE_DEREF,
-};
-
-struct unwind_user_rule_data {
- enum unwind_user_rule rule;
- s32 offset;
- unsigned int regnum;
-};
-
-struct unwind_user_frame {
- struct unwind_user_cfa_rule_data cfa;
- struct unwind_user_rule_data ra;
- struct unwind_user_rule_data fp;
- bool outermost;
-};
-
struct unwind_user_state {
unsigned long ip;
unsigned long sp;
diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile
index 146038165865..c5f9f8124564 100644
--- a/kernel/unwind/Makefile
+++ b/kernel/unwind/Makefile
@@ -1,2 +1,2 @@
obj-$(CONFIG_UNWIND_USER) += user.o deferred.o
- obj-$(CONFIG_HAVE_UNWIND_USER_SFRAME) += sframe.o
+ obj-$(CONFIG_UNWIND_SFRAME_LOOKUP) += sframe.o
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index f24997e84e05..89dd8c5a6a10 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -12,8 +12,8 @@
#include <linux/mm.h>
#include <linux/string_helpers.h>
#include <linux/sframe.h>
-#include <asm/unwind_user_sframe.h>
-#include <linux/unwind_user_types.h>
+#include <linux/unwind_types.h>
+#include <asm/unwind_sframe.h>
#include "sframe.h"
#include "sframe_debug.h"
@@ -44,8 +44,6 @@ struct sframe_fre_internal {
unsigned char dw_size;
};
-DEFINE_STATIC_SRCU(sframe_srcu);
-
static __always_inline unsigned char fre_type_to_size(unsigned char fre_type)
{
if (fre_type > 2)
@@ -60,6 +58,77 @@ static __always_inline unsigned char dataword_size_enum_to_size(unsigned char da
return 1 << dataword_size;
}
+#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME
+
+DEFINE_STATIC_SRCU(sframe_srcu);
+
+#define UNSAFE_USER_COPY(to, from, size, label) \
+ unsafe_copy_from_user(to, (void __user *)from, size, label)
+
+#define UNSAFE_USER_GET(to, from, type, label) \
+ unsafe_get_user(to, (type __user *)from, label)
+
+#else /* !CONFIG_HAVE_UNWIND_USER_SFRAME */
+
+#define UNSAFE_USER_COPY(to, from, size, label) do { \
+ (void)to; (void)from; (void)size; \
+ goto label; \
+} while (0)
+
+#define UNSAFE_USER_GET(to, from, type, label) do { \
+ (void)to; (void)from; \
+ goto label; \
+} while (0)
+
+#endif /* !CONFIG_HAVE_UNWIND_USER_SFRAME */
+
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+
+#define KERNEL_COPY(to, from, size, label) memcpy(to, (void *)from, size)
+#define KERNEL_GET(to, from, type, label) ({ (to) = *(type *)(from); })
+
+#else /* !CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
+
+#define KERNEL_COPY(to, from, size, label) do { \
+ (void)(to); (void)(from); (void)size; \
+ goto label; \
+} while (0)
+
+#define KERNEL_GET(to, from, type, label) do { \
+ (void)(to); (void)(from); \
+ goto label; \
+} while (0)
+
+#endif /* !CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
+
+#define DATA_COPY(sec, to, from, size, label) \
+({ \
+ switch (sec->sec_type) { \
+ case SFRAME_KERNEL: \
+ KERNEL_COPY(to, from, size, label); \
+ break; \
+ case SFRAME_USER: \
+ UNSAFE_USER_COPY(to, from, size, label); \
+ break; \
+ default: \
+ goto label; \
+ } \
+})
+
+#define DATA_GET(sec, to, from, type, label) \
+({ \
+ switch (sec->sec_type) { \
+ case SFRAME_KERNEL: \
+ KERNEL_GET(to, from, type, label); \
+ break; \
+ case SFRAME_USER: \
+ UNSAFE_USER_GET(to, from, type, label); \
+ break; \
+ default: \
+ goto label; \
+ } \
+})
+
static __always_inline int __read_fde(struct sframe_section *sec,
unsigned int fde_num,
struct sframe_fde_internal *fde)
@@ -69,8 +138,8 @@ static __always_inline int __read_fde(struct sframe_section *sec,
struct sframe_fda_v3 _fda;
fde_addr = sec->fdes_start + (fde_num * sizeof(struct sframe_fde_v3));
- unsafe_copy_from_user(&_fde, (void __user *)fde_addr,
- sizeof(struct sframe_fde_v3), Efault);
+ DATA_COPY(sec, &_fde, fde_addr,
+ sizeof(struct sframe_fde_v3), Efault);
func_addr = fde_addr + _fde.func_start_off;
if (func_addr < sec->text_start || func_addr > sec->text_end)
@@ -79,8 +148,8 @@ static __always_inline int __read_fde(struct sframe_section *sec,
fda_addr = sec->fres_start + _fde.fres_off;
if (fda_addr + sizeof(struct sframe_fda_v3) > sec->fres_end)
return -EINVAL;
- unsafe_copy_from_user(&_fda, (void __user *)fda_addr,
- sizeof(struct sframe_fda_v3), Efault);
+ DATA_COPY(sec, &_fda, fda_addr,
+ sizeof(struct sframe_fda_v3), Efault);
fde->func_addr = func_addr;
fde->func_size = _fde.func_size;
@@ -102,21 +171,21 @@ static __always_inline int __find_fde(struct sframe_section *sec,
struct sframe_fde_internal *fde)
{
unsigned long func_addr_low = 0, func_addr_high = ULONG_MAX;
- struct sframe_fde_v3 __user *first, *low, *high, *found = NULL;
+ struct sframe_fde_v3 *first, *low, *high, *found = NULL;
int ret;
- first = (void __user *)sec->fdes_start;
+ first = (void *)sec->fdes_start;
low = first;
high = first + sec->num_fdes - 1;
while (low <= high) {
- struct sframe_fde_v3 __user *mid;
+ struct sframe_fde_v3 *mid;
s64 func_off;
unsigned long func_addr;
mid = low + ((high - low) / 2);
- unsafe_get_user(func_off, (s64 __user *)mid, Efault);
+ DATA_GET(sec, func_off, mid, s64, Efault);
func_addr = (unsigned long)mid + func_off;
if (ip >= func_addr) {
@@ -154,47 +223,47 @@ static __always_inline int __find_fde(struct sframe_section *sec,
return -EFAULT;
}
-#define ____UNSAFE_GET_USER_INC(to, from, type, label) \
+#define ____GET_INC(sec, to, from, type, label) \
({ \
type __to; \
- unsafe_get_user(__to, (type __user *)from, label); \
+ DATA_GET(sec, __to, from, type, label); \
from += sizeof(__to); \
to = __to; \
})
-#define __UNSAFE_GET_USER_INC(to, from, size, label, u_or_s) \
+#define __GET_INC(sec, to, from, size, label, u_or_s) \
({ \
switch (size) { \
case 1: \
- ____UNSAFE_GET_USER_INC(to, from, u_or_s##8, label); \
+ ____GET_INC(sec, to, from, u_or_s##8, label); \
break; \
case 2: \
- ____UNSAFE_GET_USER_INC(to, from, u_or_s##16, label); \
+ ____GET_INC(sec, to, from, u_or_s##16, label); \
break; \
case 4: \
- ____UNSAFE_GET_USER_INC(to, from, u_or_s##32, label); \
+ ____GET_INC(sec, to, from, u_or_s##32, label); \
break; \
default: \
return -EFAULT; \
} \
})
-#define UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label) \
- __UNSAFE_GET_USER_INC(to, from, size, label, u)
+#define GET_UNSIGNED_INC(sec, to, from, size, label) \
+ __GET_INC(sec, to, from, size, label, u)
-#define UNSAFE_GET_USER_SIGNED_INC(to, from, size, label) \
- __UNSAFE_GET_USER_INC(to, from, size, label, s)
+#define GET_SIGNED_INC(sec, to, from, size, label) \
+ __GET_INC(sec, to, from, size, label, s)
-#define UNSAFE_GET_USER_INC(to, from, size, label) \
- _Generic(to, \
- u8 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \
- u16 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \
- u32 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \
- u64 : UNSAFE_GET_USER_UNSIGNED_INC(to, from, size, label), \
- s8 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label), \
- s16 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label), \
- s32 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label), \
- s64 : UNSAFE_GET_USER_SIGNED_INC(to, from, size, label))
+#define GET_INC(sec, to, from, size, label) \
+ _Generic(to, \
+ u8 : GET_UNSIGNED_INC(sec, to, from, size, label), \
+ u16 : GET_UNSIGNED_INC(sec, to, from, size, label), \
+ u32 : GET_UNSIGNED_INC(sec, to, from, size, label), \
+ u64 : GET_UNSIGNED_INC(sec, to, from, size, label), \
+ s8 : GET_SIGNED_INC(sec, to, from, size, label), \
+ s16 : GET_SIGNED_INC(sec, to, from, size, label), \
+ s32 : GET_SIGNED_INC(sec, to, from, size, label), \
+ s64 : GET_SIGNED_INC(sec, to, from, size, label))
static __always_inline int
__read_regular_fre_datawords(struct sframe_section *sec,
@@ -207,19 +276,19 @@ __read_regular_fre_datawords(struct sframe_section *sec,
s32 cfa_off, ra_off, fp_off;
unsigned int cfa_regnum;
- UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault);
+ GET_INC(sec, cfa_off, cur, dataword_size, Efault);
dataword_count--;
ra_off = sec->ra_off;
if (!ra_off && dataword_count) {
dataword_count--;
- UNSAFE_GET_USER_INC(ra_off, cur, dataword_size, Efault);
+ GET_INC(sec, ra_off, cur, dataword_size, Efault);
}
fp_off = sec->fp_off;
if (!fp_off && dataword_count) {
dataword_count--;
- UNSAFE_GET_USER_INC(fp_off, cur, dataword_size, Efault);
+ GET_INC(sec, fp_off, cur, dataword_size, Efault);
}
if (dataword_count)
@@ -255,17 +324,17 @@ __read_flex_fde_fre_datawords(struct sframe_section *sec,
if (dataword_count < 2)
return -EFAULT;
- UNSAFE_GET_USER_INC(cfa_ctl, cur, dataword_size, Efault);
- UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault);
+ GET_INC(sec, cfa_ctl, cur, dataword_size, Efault);
+ GET_INC(sec, cfa_off, cur, dataword_size, Efault);
dataword_count -= 2;
ra_off = sec->ra_off;
ra_ctl = ra_off ? 2 : 0; /* regnum=0, deref_p=(ra_off != 0), reg_p=0 */
if (dataword_count >= 2) {
- UNSAFE_GET_USER_INC(ra_ctl, cur, dataword_size, Efault);
+ GET_INC(sec, ra_ctl, cur, dataword_size, Efault);
dataword_count--;
if (ra_ctl) {
- UNSAFE_GET_USER_INC(ra_off, cur, dataword_size, Efault);
+ GET_INC(sec, ra_off, cur, dataword_size, Efault);
dataword_count--;
} else {
/* Padding RA location info */
@@ -276,10 +345,10 @@ __read_flex_fde_fre_datawords(struct sframe_section *sec,
fp_off = sec->fp_off;
fp_ctl = fp_off ? 2 : 0; /* regnum=0, deref_p=(fp_off != 0), reg_p=0 */
if (dataword_count >= 2) {
- UNSAFE_GET_USER_INC(fp_ctl, cur, dataword_size, Efault);
+ GET_INC(sec, fp_ctl, cur, dataword_size, Efault);
dataword_count--;
if (fp_ctl) {
- UNSAFE_GET_USER_INC(fp_off, cur, dataword_size, Efault);
+ GET_INC(sec, fp_off, cur, dataword_size, Efault);
dataword_count--;
} else {
/* Padding FP location info */
@@ -353,11 +422,11 @@ static __always_inline int __read_fre(struct sframe_section *sec,
if (fre_addr + addr_size + 1 > sec->fres_end)
return -EFAULT;
- UNSAFE_GET_USER_INC(ip_off, cur, addr_size, Efault);
+ GET_INC(sec, ip_off, cur, addr_size, Efault);
if (fde_pctype == SFRAME_FDE_PCTYPE_INC && ip_off > fde->func_size)
return -EFAULT;
- UNSAFE_GET_USER_INC(info, cur, 1, Efault);
+ GET_INC(sec, info, cur, 1, Efault);
dataword_count = SFRAME_V3_FRE_DATAWORD_COUNT(info);
dataword_size = dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE(info));
if (!dataword_size)
@@ -380,7 +449,7 @@ static __always_inline int __read_fre(struct sframe_section *sec,
}
static __always_inline int
-sframe_init_cfa_rule_data(struct unwind_user_cfa_rule_data *cfa_rule_data,
+sframe_init_cfa_rule_data(struct unwind_cfa_rule_data *cfa_rule_data,
u32 ctlword, s32 offset)
{
bool deref_p = SFRAME_V3_FLEX_FDE_CTLWORD_DEREF_P(ctlword);
@@ -391,13 +460,13 @@ sframe_init_cfa_rule_data(struct unwind_user_cfa_rule_data *cfa_rule_data,
switch (regnum) {
case SFRAME_REG_SP:
- cfa_rule_data->rule = UNWIND_USER_CFA_RULE_SP_OFFSET;
+ cfa_rule_data->rule = UNWIND_CFA_RULE_SP_OFFSET;
break;
case SFRAME_REG_FP:
- cfa_rule_data->rule = UNWIND_USER_CFA_RULE_FP_OFFSET;
+ cfa_rule_data->rule = UNWIND_CFA_RULE_FP_OFFSET;
break;
default:
- cfa_rule_data->rule = UNWIND_USER_CFA_RULE_REG_OFFSET;
+ cfa_rule_data->rule = UNWIND_CFA_RULE_REG_OFFSET;
cfa_rule_data->regnum = regnum;
}
} else {
@@ -405,7 +474,7 @@ sframe_init_cfa_rule_data(struct unwind_user_cfa_rule_data *cfa_rule_data,
}
if (deref_p)
- cfa_rule_data->rule |= UNWIND_USER_RULE_DEREF;
+ cfa_rule_data->rule |= UNWIND_RULE_DEREF;
cfa_rule_data->offset = offset;
@@ -413,27 +482,27 @@ sframe_init_cfa_rule_data(struct unwind_user_cfa_rule_data *cfa_rule_data,
}
static __always_inline void
-sframe_init_rule_data(struct unwind_user_rule_data *rule_data,
+sframe_init_rule_data(struct unwind_rule_data *rule_data,
u32 ctlword, s32 offset)
{
bool deref_p = SFRAME_V3_FLEX_FDE_CTLWORD_DEREF_P(ctlword);
bool reg_p = SFRAME_V3_FLEX_FDE_CTLWORD_REG_P(ctlword);
if (!ctlword && !offset) {
- rule_data->rule = UNWIND_USER_RULE_RETAIN;
+ rule_data->rule = UNWIND_RULE_RETAIN;
return;
}
if (reg_p) {
unsigned int regnum = SFRAME_V3_FLEX_FDE_CTLWORD_REGNUM(ctlword);
- rule_data->rule = UNWIND_USER_RULE_REG_OFFSET;
+ rule_data->rule = UNWIND_RULE_REG_OFFSET;
rule_data->regnum = regnum;
} else {
- rule_data->rule = UNWIND_USER_RULE_CFA_OFFSET;
+ rule_data->rule = UNWIND_RULE_CFA_OFFSET;
}
if (deref_p)
- rule_data->rule |= UNWIND_USER_RULE_DEREF;
+ rule_data->rule |= UNWIND_RULE_DEREF;
rule_data->offset = offset;
}
@@ -441,7 +510,7 @@ sframe_init_rule_data(struct unwind_user_rule_data *rule_data,
static __always_inline int __find_fre(struct sframe_section *sec,
struct sframe_fde_internal *fde,
unsigned long ip,
- struct unwind_user_frame *frame)
+ struct unwind_frame *frame)
{
unsigned char fde_pctype = SFRAME_V3_FDE_PCTYPE(fde->info);
struct sframe_fre_internal *fre, *prev_fre = NULL;
@@ -501,40 +570,18 @@ static __always_inline int __find_fre(struct sframe_section *sec,
return 0;
}
-int sframe_find(unsigned long ip, struct unwind_user_frame *frame)
+static __always_inline int __sframe_find(struct sframe_section *sec,
+ unsigned long ip,
+ struct unwind_frame *frame)
{
- struct mm_struct *mm = current->mm;
- struct sframe_section *sec;
struct sframe_fde_internal fde;
int ret;
- if (!mm)
- return -EINVAL;
-
- guard(srcu)(&sframe_srcu);
-
- sec = mtree_load(&mm->sframe_mt, ip);
- if (!sec)
- return -EINVAL;
-
- if (!user_read_access_begin((void __user *)sec->sframe_start,
- sec->sframe_end - sec->sframe_start))
- return -EFAULT;
-
ret = __find_fde(sec, ip, &fde);
if (ret)
- goto end;
-
- ret = __find_fre(sec, &fde, ip, frame);
-end:
- user_read_access_end();
-
- if (ret == -EFAULT) {
- dbg_sec("removing bad .sframe section\n");
- WARN_ON_ONCE(sframe_remove_section(sec->sframe_start));
- }
+ return ret;
- return ret;
+ return __find_fre(sec, &fde, ip, frame);
}
#ifdef CONFIG_SFRAME_VALIDATION
@@ -657,20 +704,23 @@ static int sframe_validate_section(struct sframe_section *sec) { return 0; }
#endif /* !CONFIG_SFRAME_VALIDATION */
-static void free_section(struct sframe_section *sec)
-{
- dbg_free(sec);
- kfree(sec);
-}
-
static int sframe_read_header(struct sframe_section *sec)
{
unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end;
struct sframe_header shdr;
unsigned int num_fdes;
- if (copy_from_user(&shdr, (void __user *)sec->sframe_start, sizeof(shdr))) {
- dbg_sec("header usercopy failed\n");
+ switch (sec->sec_type) {
+ case SFRAME_USER:
+ if (copy_from_user(&shdr, (void __user *)sec->sframe_start, sizeof(shdr))) {
+ dbg_sec("header usercopy failed\n");
+ return -EFAULT;
+ }
+ break;
+ case SFRAME_KERNEL:
+ shdr = *(struct sframe_header *)sec->sframe_start;
+ break;
+ default:
return -EFAULT;
}
@@ -717,6 +767,45 @@ static int sframe_read_header(struct sframe_section *sec)
return 0;
}
+#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME
+
+int sframe_find_user(unsigned long ip, struct unwind_frame *frame)
+{
+ struct mm_struct *mm = current->mm;
+ struct sframe_section *sec;
+ int ret;
+
+ if (!mm)
+ return -EINVAL;
+
+ guard(srcu)(&sframe_srcu);
+
+ sec = mtree_load(&mm->sframe_mt, ip);
+ if (!sec)
+ return -EINVAL;
+
+ if (!user_read_access_begin((void __user *)sec->sframe_start,
+ sec->sframe_end - sec->sframe_start))
+ return -EFAULT;
+
+ ret = __sframe_find(sec, ip, frame);
+
+ user_read_access_end();
+
+ if (ret == -EFAULT) {
+ dbg_sec("removing bad .sframe section\n");
+ WARN_ON_ONCE(sframe_remove_section(sec->sframe_start));
+ }
+
+ return ret;
+}
+
+static void free_section(struct sframe_section *sec)
+{
+ dbg_free(sec);
+ kfree(sec);
+}
+
int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end,
unsigned long text_start, unsigned long text_end)
{
@@ -753,6 +842,7 @@ int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end,
if (!sec)
return -ENOMEM;
+ sec->sec_type = SFRAME_USER;
sec->sframe_start = sframe_start;
sec->sframe_end = sframe_end;
sec->text_start = text_start;
@@ -838,3 +928,5 @@ void sframe_free_mm(struct mm_struct *mm)
mtree_destroy(&mm->sframe_mt);
}
+
+#endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */
diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
index eb7d9489f671..9e57dd79559a 100644
--- a/kernel/unwind/user.c
+++ b/kernel/unwind/user.c
@@ -8,6 +8,7 @@
#include <linux/unwind_user.h>
#include <linux/uaccess.h>
#include <linux/sframe.h>
+#include <linux/unwind_types.h>
#define for_each_user_frame(state) \
for (unwind_user_start(state); !(state)->done; unwind_user_next(state))
@@ -28,7 +29,7 @@ get_user_word(unsigned long *word, unsigned long base, int off, unsigned int ws)
}
static int unwind_user_next_common(struct unwind_user_state *state,
- const struct unwind_user_frame *frame)
+ const struct unwind_frame *frame)
{
unsigned long cfa, fp, ra;
@@ -40,16 +41,16 @@ static int unwind_user_next_common(struct unwind_user_state *state,
/* Get the Canonical Frame Address (CFA) */
switch (frame->cfa.rule) {
- case UNWIND_USER_CFA_RULE_SP_OFFSET:
+ case UNWIND_CFA_RULE_SP_OFFSET:
cfa = state->sp;
break;
- case UNWIND_USER_CFA_RULE_FP_OFFSET:
+ case UNWIND_CFA_RULE_FP_OFFSET:
if (state->fp < state->sp)
return -EINVAL;
cfa = state->fp;
break;
- case UNWIND_USER_CFA_RULE_REG_OFFSET:
- case UNWIND_USER_CFA_RULE_REG_OFFSET_DEREF:
+ case UNWIND_CFA_RULE_REG_OFFSET:
+ case UNWIND_CFA_RULE_REG_OFFSET_DEREF:
if (!state->topmost || unwind_user_get_reg(&cfa, frame->cfa.regnum))
return -EINVAL;
break;
@@ -58,7 +59,7 @@ static int unwind_user_next_common(struct unwind_user_state *state,
return -EINVAL;
}
cfa += frame->cfa.offset;
- if (frame->cfa.rule & UNWIND_USER_RULE_DEREF &&
+ if (frame->cfa.rule & UNWIND_RULE_DEREF &&
get_user_word(&cfa, cfa, 0, state->ws))
return -EINVAL;
@@ -76,16 +77,16 @@ static int unwind_user_next_common(struct unwind_user_state *state,
/* Get the Return Address (RA) */
switch (frame->ra.rule) {
- case UNWIND_USER_RULE_RETAIN:
+ case UNWIND_RULE_RETAIN:
if (!state->topmost || unwind_user_get_ra_reg(&ra))
return -EINVAL;
break;
/* UNWIND_USER_RULE_CFA_OFFSET not implemented on purpose */
- case UNWIND_USER_RULE_CFA_OFFSET_DEREF:
+ case UNWIND_RULE_CFA_OFFSET_DEREF:
ra = cfa + frame->ra.offset;
break;
- case UNWIND_USER_RULE_REG_OFFSET:
- case UNWIND_USER_RULE_REG_OFFSET_DEREF:
+ case UNWIND_RULE_REG_OFFSET:
+ case UNWIND_RULE_REG_OFFSET_DEREF:
if (!state->topmost || unwind_user_get_reg(&ra, frame->ra.regnum))
return -EINVAL;
ra += frame->ra.offset;
@@ -94,21 +95,21 @@ static int unwind_user_next_common(struct unwind_user_state *state,
WARN_ON_ONCE(1);
return -EINVAL;
}
- if (frame->ra.rule & UNWIND_USER_RULE_DEREF &&
+ if (frame->ra.rule & UNWIND_RULE_DEREF &&
get_user_word(&ra, ra, 0, state->ws))
return -EINVAL;
/* Get the Frame Pointer (FP) */
switch (frame->fp.rule) {
- case UNWIND_USER_RULE_RETAIN:
+ case UNWIND_RULE_RETAIN:
fp = state->fp;
break;
/* UNWIND_USER_RULE_CFA_OFFSET not implemented on purpose */
- case UNWIND_USER_RULE_CFA_OFFSET_DEREF:
+ case UNWIND_RULE_CFA_OFFSET_DEREF:
fp = cfa + frame->fp.offset;
break;
- case UNWIND_USER_RULE_REG_OFFSET:
- case UNWIND_USER_RULE_REG_OFFSET_DEREF:
+ case UNWIND_RULE_REG_OFFSET:
+ case UNWIND_RULE_REG_OFFSET_DEREF:
if (!state->topmost || unwind_user_get_reg(&fp, frame->fp.regnum))
return -EINVAL;
fp += frame->fp.offset;
@@ -117,7 +118,7 @@ static int unwind_user_next_common(struct unwind_user_state *state,
WARN_ON_ONCE(1);
return -EINVAL;
}
- if (frame->fp.rule & UNWIND_USER_RULE_DEREF &&
+ if (frame->fp.rule & UNWIND_RULE_DEREF &&
get_user_word(&fp, fp, 0, state->ws))
return -EINVAL;
@@ -133,13 +134,13 @@ static int unwind_user_next_fp(struct unwind_user_state *state)
struct pt_regs *regs = task_pt_regs(current);
if (state->topmost && unwind_user_at_function_start(regs)) {
- const struct unwind_user_frame fp_entry_frame = {
+ const struct unwind_frame fp_entry_frame = {
ARCH_INIT_USER_FP_ENTRY_FRAME(state->ws)
};
return unwind_user_next_common(state, &fp_entry_frame);
}
- const struct unwind_user_frame fp_frame = {
+ const struct unwind_frame fp_frame = {
ARCH_INIT_USER_FP_FRAME(state->ws)
};
return unwind_user_next_common(state, &fp_frame);
@@ -147,10 +148,10 @@ static int unwind_user_next_fp(struct unwind_user_state *state)
static int unwind_user_next_sframe(struct unwind_user_state *state)
{
- struct unwind_user_frame frame;
+ struct unwind_frame frame;
/* sframe expects the frame to be local storage */
- if (sframe_find(state->ip, &frame))
+ if (sframe_find_user(state->ip, &frame))
return -ENOENT;
return unwind_user_next_common(state, &frame);
}
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* [PATCH v5 2/8] arm64, unwind: build kernel with sframe V3 info
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
Build with -Wa,--gsframe-3 flags to generate a .sframe section. This
will be used for in-kernel reliable stacktrace in cases where the frame
pointer alone is insufficient.
Currently, the sframe format only supports arm64, x86_64 and s390x
architectures.
Signed-off-by: Weinan Liu <wnliu@google.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
MAINTAINERS | 1 +
Makefile | 8 ++++++++
arch/Kconfig | 21 +++++++++++++++++++++
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/unwind_sframe.h | 8 ++++++++
arch/arm64/kernel/vdso/Makefile | 2 +-
include/asm-generic/sections.h | 4 ++++
include/asm-generic/vmlinux.lds.h | 15 +++++++++++++++
8 files changed, 59 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/include/asm/unwind_sframe.h
diff --git a/MAINTAINERS b/MAINTAINERS
index cfc7dec88da4..a7d75f9cb5f4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -27561,6 +27561,7 @@ STACK UNWINDING
M: Josh Poimboeuf <jpoimboe@kernel.org>
M: Steven Rostedt <rostedt@goodmis.org>
S: Maintained
+F: arch/*/include/asm/unwind_sframe.h
F: include/linux/sframe.h
F: include/linux/unwind*.h
F: kernel/unwind/
diff --git a/Makefile b/Makefile
index 2b15f0b4a0cb..6c94a5257679 100644
--- a/Makefile
+++ b/Makefile
@@ -1110,6 +1110,14 @@ endif
# Ensure compilers do not transform certain loops into calls to wcslen()
KBUILD_CFLAGS += -fno-builtin-wcslen
+# build with sframe table
+ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+CC_FLAGS_SFRAME := -Wa,--gsframe-3
+KBUILD_CFLAGS += $(CC_FLAGS_SFRAME)
+KBUILD_AFLAGS += $(CC_FLAGS_SFRAME)
+export CC_FLAGS_SFRAME
+endif
+
# change __FILE__ to the relative path to the source directory
ifdef building_out_of_srctree
KBUILD_CPPFLAGS += -fmacro-prefix-map=$(srcroot)/=
diff --git a/arch/Kconfig b/arch/Kconfig
index d7caf2e245ce..8d27b3249e7a 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -520,6 +520,27 @@ config SFRAME_VALIDATION
If unsure, say N.
+config ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
+ bool
+ help
+ An architecture can select this if it enables the SFrame (Simple
+ Frame) unwinder for unwinding kernel stack traces. It uses an unwind
+ table that is directly generated by the toolchain based on DWARF CFI
+ information.
+
+config HAVE_UNWIND_KERNEL_SFRAME
+ bool "Sframe unwinder"
+ depends on AS_SFRAME3
+ depends on 64BIT
+ depends on ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
+ select UNWIND_SFRAME_LOOKUP
+ help
+ This option enables the SFrame (Simple Frame) unwinder for unwinding
+ kernel stack traces. It uses unwind an table that is directly
+ generated by the toolchain based on DWARF CFI information. In
+ practice, this can provide more reliable stacktrace results than
+ unwinding with frame pointers alone.
+
config HAVE_PERF_REGS
bool
help
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 38dba5f7e4d2..f7ae8eaaadc4 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -112,6 +112,7 @@ config ARM64
select ARCH_SUPPORTS_SCHED_SMT
select ARCH_SUPPORTS_SCHED_CLUSTER
select ARCH_SUPPORTS_SCHED_MC
+ select ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
select ARCH_WANT_DEFAULT_BPF_JIT
diff --git a/arch/arm64/include/asm/unwind_sframe.h b/arch/arm64/include/asm/unwind_sframe.h
new file mode 100644
index 000000000000..876412881196
--- /dev/null
+++ b/arch/arm64/include/asm/unwind_sframe.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ARM64_UNWIND_SFRAME_H
+#define _ASM_ARM64_UNWIND_SFRAME_H
+
+#define SFRAME_REG_SP 31
+#define SFRAME_REG_FP 29
+
+#endif /* _ASM_ARM64_UNWIND_SFRAME_H */
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 7dec05dd33b7..c60ef921956f 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -38,7 +38,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
CC_FLAGS_REMOVE_VDSO := $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
$(RANDSTRUCT_CFLAGS) $(KSTACK_ERASE_CFLAGS) \
$(GCC_PLUGINS_CFLAGS) \
- $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
+ $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(CC_FLAGS_SFRAME) \
-Wmissing-prototypes -Wmissing-declarations
CC_FLAGS_ADD_VDSO := -O2 -mcmodel=tiny -fasynchronous-unwind-tables
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 0755bc39b0d8..336d27011a58 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -31,6 +31,7 @@
* __irqentry_text_start, __irqentry_text_end
* __softirqentry_text_start, __softirqentry_text_end
* __start_opd, __end_opd
+ * __start_sframe, __end_sframe
*/
extern char _text[], _stext[], _etext[];
extern char _data[], _sdata[], _edata[];
@@ -53,6 +54,9 @@ extern char __ctors_start[], __ctors_end[];
/* Start and end of .opd section - used for function descriptors. */
extern char __start_opd[], __end_opd[];
+/* Start and end of .sframe section - used for stack unwinding. */
+extern char __start_sframe[], __end_sframe[];
+
/* Start and end of instrumentation protected text section */
extern char __noinstr_text_start[], __noinstr_text_end[];
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 1e1580febe4b..090da633db92 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -491,6 +491,8 @@
*(.rodata1) \
} \
\
+ SFRAME \
+ \
/* PCI quirks */ \
.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
BOUNDED_SECTION_PRE_LABEL(.pci_fixup_early, _pci_fixups_early, __start, __end) \
@@ -911,6 +913,19 @@
#define TRACEDATA
#endif
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+#define SFRAME \
+ /* sframe */ \
+ .sframe : AT(ADDR(.sframe) - LOAD_OFFSET) { \
+ __start_sframe = .; \
+ KEEP(*(.sframe)) \
+ KEEP(*(.init.sframe)) \
+ __end_sframe = .; \
+ }
+#else
+#define SFRAME
+#endif
+
#ifdef CONFIG_PRINTK_INDEX
#define PRINTK_INDEX \
.printk_index : AT(ADDR(.printk_index) - LOAD_OFFSET) { \
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* [PATCH v5 3/8] arm64: entry: add unwind info for various kernel entries
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
From: Weinan Liu <wnliu@google.com>
DWARF CFI (Call Frame Information) specifies how to recover the return
address and callee-saved registers at each PC in a given function.
Compilers are able to generate the CFI annotations when they compile
the code to assembly language. For handcrafted assembly, we need to
annotate them by hand.
Annotate minimal CFI to enable stacktracing using SFrame for kernel
exception entries through el1*_64_*() paths and irq entries through
call_on_irq_stack()
Signed-off-by: Weinan Liu <wnliu@google.com>
Suggested-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
arch/arm64/kernel/entry.S | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index f8018b5c1f9a..dc55b0b19cfa 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -30,6 +30,12 @@
#include <asm/asm-uaccess.h>
#include <asm/unistd.h>
+/*
+ * Do not generate .eh_frame. Only generate .debug_frame and optionally
+ * .sframe (via assembler option --gsframe[-N]).
+ */
+ .cfi_sections .debug_frame
+
.macro clear_gp_regs
.irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
mov x\n, xzr
@@ -575,7 +581,16 @@ SYM_CODE_START_LOCAL(el\el\ht\()_\regsize\()_\label)
.if \el == 0
b ret_to_user
.else
+ /*
+ * Minimal DWARF CFI for unwinding across the call above.
+ * Enable unwinding for el1*_64_*() path only.
+ */
+ .cfi_startproc
+ .cfi_def_cfa_offset PT_REGS_SIZE
+ .cfi_offset 29, S_FP - PT_REGS_SIZE
+ .cfi_offset 30, S_LR - PT_REGS_SIZE
b ret_to_kernel
+ .cfi_endproc
.endif
SYM_CODE_END(el\el\ht\()_\regsize\()_\label)
.endm
@@ -872,6 +887,7 @@ NOKPROBE(ret_from_fork)
* Calls func(regs) using this CPU's irq stack and shadow irq stack.
*/
SYM_FUNC_START(call_on_irq_stack)
+ .cfi_startproc
save_and_disable_daif x9
#ifdef CONFIG_SHADOW_CALL_STACK
get_current_task x16
@@ -882,6 +898,9 @@ SYM_FUNC_START(call_on_irq_stack)
/* Create a frame record to save our LR and SP (implicit in FP) */
stp x29, x30, [sp, #-16]!
mov x29, sp
+ .cfi_def_cfa 29, 16
+ .cfi_offset 29, -16
+ .cfi_offset 30, -8
ldr_this_cpu x16, irq_stack_ptr, x17
@@ -897,9 +916,13 @@ SYM_FUNC_START(call_on_irq_stack)
*/
mov sp, x29
ldp x29, x30, [sp], #16
+ .cfi_restore 29
+ .cfi_restore 30
+ .cfi_def_cfa 31, 0
scs_load_current
restore_irq x9
ret
+ .cfi_endproc
SYM_FUNC_END(call_on_irq_stack)
NOKPROBE(call_on_irq_stack)
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* [PATCH v5 4/8] sframe: Provide PC lookup for vmlinux .sframe section
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
With SFRAME_UNWINDER, read in the .sframe section at boot. This provides
unwind data as an alternative/supplement to frame pointer-based
unwinding.
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
arch/arm64/kernel/setup.c | 2 ++
include/linux/sframe.h | 14 ++++++++++++++
kernel/unwind/sframe.c | 36 ++++++++++++++++++++++++++++++++++++
3 files changed, 52 insertions(+)
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 23c05dc7a8f2..4a633bc7aefb 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -32,6 +32,7 @@
#include <linux/sched/task.h>
#include <linux/scs.h>
#include <linux/mm.h>
+#include <linux/sframe.h>
#include <asm/acpi.h>
#include <asm/fixmap.h>
@@ -375,6 +376,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
"This indicates a broken bootloader or old kernel\n",
boot_args[1], boot_args[2], boot_args[3]);
}
+ init_sframe_table();
}
static inline bool cpu_can_disable(unsigned int cpu)
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index 0cb2924367bc..5b7341b61a7c 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -69,4 +69,18 @@ static inline int sframe_find_user(unsigned long ip, struct unwind_frame *frame)
#endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+
+void __init init_sframe_table(void);
+void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
+ void *text, size_t text_size);
+
+extern int sframe_find_kernel(unsigned long ip, struct unwind_frame *frame);
+
+#else
+
+static inline void __init init_sframe_table(void) {}
+
+#endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
+
#endif /* _LINUX_SFRAME_H */
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 89dd8c5a6a10..430bff9533ee 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -14,10 +14,20 @@
#include <linux/sframe.h>
#include <linux/unwind_types.h>
#include <asm/unwind_sframe.h>
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+#include <linux/kallsyms.h>
+#endif
#include "sframe.h"
#include "sframe_debug.h"
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+
+static bool sframe_init __ro_after_init;
+static struct sframe_section kernel_sfsec __ro_after_init;
+
+#endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
+
struct sframe_fde_internal {
unsigned long func_addr;
u32 func_size;
@@ -930,3 +940,29 @@ void sframe_free_mm(struct mm_struct *mm)
}
#endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */
+
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+
+int sframe_find_kernel(unsigned long ip, struct unwind_frame *frame)
+{
+ if (!frame || !sframe_init)
+ return -EINVAL;
+
+ return __sframe_find(&kernel_sfsec, ip, frame);
+}
+
+void __init init_sframe_table(void)
+{
+ kernel_sfsec.sec_type = SFRAME_KERNEL;
+ kernel_sfsec.sframe_start = (unsigned long)__start_sframe;
+ kernel_sfsec.sframe_end = (unsigned long)__end_sframe;
+ kernel_sfsec.text_start = (unsigned long)_stext;
+ kernel_sfsec.text_end = (unsigned long)_etext;
+
+ if (WARN_ON(sframe_read_header(&kernel_sfsec)))
+ return;
+
+ sframe_init = true;
+}
+
+#endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* [PATCH v5 5/8] sframe: Allow unsorted FDEs
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
The .sframe in kernel modules is built without SFRAME_F_FDE_SORTED set.
In order to allow sframe PC lookup in modules, add a code path to handle
unsorted FDE tables by doing a simple linear search.
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
include/linux/sframe.h | 1 +
kernel/unwind/sframe.c | 45 +++++++++++++++++++++++++++++++++++++-----
2 files changed, 41 insertions(+), 5 deletions(-)
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index 5b7341b61a7c..8ae31ed36226 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -28,6 +28,7 @@ struct sframe_section {
unsigned long fres_start;
unsigned long fres_end;
unsigned int num_fdes;
+ bool fdes_sorted;
signed char ra_off;
signed char fp_off;
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 430bff9533ee..dcf4deb378dc 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -176,9 +176,35 @@ static __always_inline int __read_fde(struct sframe_section *sec,
return -EFAULT;
}
-static __always_inline int __find_fde(struct sframe_section *sec,
- unsigned long ip,
- struct sframe_fde_internal *fde)
+static __always_inline int __find_fde_unsorted(struct sframe_section *sec,
+ unsigned long ip,
+ struct sframe_fde_internal *fde)
+{
+ struct sframe_fde_v3 *cur, *start, *end;
+
+ start = (struct sframe_fde_v3 *)sec->fdes_start;
+ end = start + sec->num_fdes;
+
+ for (cur = start; cur < end; cur++) {
+ s64 func_off;
+ u32 func_size;
+ unsigned long func_addr;
+
+ DATA_GET(sec, func_off, &cur->func_start_off, s64, Efault);
+ DATA_GET(sec, func_size, &cur->func_size, u32, Efault);
+ func_addr = (unsigned long)cur + func_off;
+
+ if (ip >= func_addr && ip < func_addr + func_size)
+ return __read_fde(sec, cur - start, fde);
+ }
+ return -EINVAL;
+Efault:
+ return -EFAULT;
+}
+
+static __always_inline int __find_fde_sorted(struct sframe_section *sec,
+ unsigned long ip,
+ struct sframe_fde_internal *fde)
{
unsigned long func_addr_low = 0, func_addr_high = ULONG_MAX;
struct sframe_fde_v3 *first, *low, *high, *found = NULL;
@@ -233,6 +259,15 @@ static __always_inline int __find_fde(struct sframe_section *sec,
return -EFAULT;
}
+static __always_inline int __find_fde(struct sframe_section *sec,
+ unsigned long ip,
+ struct sframe_fde_internal *fde)
+{
+ if (sec->fdes_sorted)
+ return __find_fde_sorted(sec, ip, fde);
+ return __find_fde_unsorted(sec, ip, fde);
+}
+
#define ____GET_INC(sec, to, from, type, label) \
({ \
type __to; \
@@ -657,7 +692,7 @@ static int sframe_validate_section(struct sframe_section *sec)
return ret;
ip = fde.func_addr;
- if (ip <= prev_ip) {
+ if (sec->fdes_sorted && ip <= prev_ip) {
dbg_sec("fde %u not sorted\n", i);
return -EFAULT;
}
@@ -736,7 +771,6 @@ static int sframe_read_header(struct sframe_section *sec)
if (shdr.preamble.magic != SFRAME_MAGIC ||
shdr.preamble.version != SFRAME_VERSION_3 ||
- !(shdr.preamble.flags & SFRAME_F_FDE_SORTED) ||
!(shdr.preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) ||
shdr.auxhdr_len) {
dbg_sec("bad/unsupported sframe header\n");
@@ -766,6 +800,7 @@ static int sframe_read_header(struct sframe_section *sec)
return -EINVAL;
}
+ sec->fdes_sorted = shdr.preamble.flags & SFRAME_F_FDE_SORTED;
sec->num_fdes = num_fdes;
sec->fdes_start = fdes_start;
sec->fres_start = fres_start;
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* [PATCH v5 6/8] arm64/module, sframe: Add sframe support for modules
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
Add sframe table to mod_arch_specific and support sframe PC lookups when
an .sframe section can be found on incoming modules.
Signed-off-by: Weinan Liu <wnliu@google.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
arch/arm64/include/asm/module.h | 6 +++++
arch/arm64/kernel/module.c | 8 +++++++
include/linux/sframe.h | 2 ++
kernel/unwind/sframe.c | 40 +++++++++++++++++++++++++++++++--
4 files changed, 54 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h
index fb9b88eebeb1..07f309c51eee 100644
--- a/arch/arm64/include/asm/module.h
+++ b/arch/arm64/include/asm/module.h
@@ -6,6 +6,7 @@
#define __ASM_MODULE_H
#include <asm-generic/module.h>
+#include <linux/sframe.h>
struct mod_plt_sec {
int plt_shndx;
@@ -17,6 +18,11 @@ struct mod_arch_specific {
struct mod_plt_sec core;
struct mod_plt_sec init;
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+ struct sframe_section sframe_sec;
+ bool sframe_init;
+#endif
+
/* for CONFIG_DYNAMIC_FTRACE */
struct plt_entry *ftrace_trampolines;
struct plt_entry *init_ftrace_trampolines;
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index 24adb581af0e..427f187e9531 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -18,6 +18,7 @@
#include <linux/moduleloader.h>
#include <linux/random.h>
#include <linux/scs.h>
+#include <linux/sframe.h>
#include <asm/alternative.h>
#include <asm/insn.h>
@@ -515,5 +516,12 @@ int module_finalize(const Elf_Ehdr *hdr,
}
}
+ s = find_section(hdr, sechdrs, ".sframe");
+ if (s) {
+ struct module_memory *t = &me->mem[MOD_TEXT];
+
+ sframe_module_init(me, (void *)s->sh_addr, s->sh_size,
+ t->base, t->size);
+ }
return module_init_ftrace_plt(hdr, sechdrs, me);
}
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index 8ae31ed36226..27f5a66190af 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -81,6 +81,8 @@ extern int sframe_find_kernel(unsigned long ip, struct unwind_frame *frame);
#else
static inline void __init init_sframe_table(void) {}
+static inline void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
+ void *text, size_t text_size) {}
#endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index dcf4deb378dc..70001c8e586d 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -980,10 +980,27 @@ void sframe_free_mm(struct mm_struct *mm)
int sframe_find_kernel(unsigned long ip, struct unwind_frame *frame)
{
- if (!frame || !sframe_init)
+ struct sframe_section *sec;
+
+ if (!frame)
return -EINVAL;
- return __sframe_find(&kernel_sfsec, ip, frame);
+ if (is_ksym_addr(ip)) {
+ if (!sframe_init)
+ return -EINVAL;
+
+ sec = &kernel_sfsec;
+ } else {
+ struct module *mod;
+
+ mod = __module_address(ip);
+ if (!mod || !mod->arch.sframe_init)
+ return -EINVAL;
+
+ sec = &mod->arch.sframe_sec;
+ }
+
+ return __sframe_find(sec, ip, frame);
}
void __init init_sframe_table(void)
@@ -1000,4 +1017,23 @@ void __init init_sframe_table(void)
sframe_init = true;
}
+void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
+ void *text, size_t text_size)
+{
+ struct sframe_section sec;
+
+ memset(&sec, 0, sizeof(sec));
+ sec.sec_type = SFRAME_KERNEL;
+ sec.sframe_start = (unsigned long)sframe;
+ sec.sframe_end = (unsigned long)sframe + sframe_size;
+ sec.text_start = (unsigned long)text;
+ sec.text_end = (unsigned long)text + text_size;
+
+ if (WARN_ON(sframe_read_header(&sec)))
+ return;
+
+ mod->arch.sframe_sec = sec;
+ mod->arch.sframe_init = true;
+}
+
#endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* [PATCH v5 7/8] sframe: Introduce in-kernel SFRAME_VALIDATION
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
Generalize the __safe* helpers to support a non-user-access code path.
This requires arch-specific function address validation. This is because
arm64 vmlinux keeps .exit.text (normally discarded), and .rodata.text
sections both of which lie outside the bounds of the normal .text.
.rodata.text contains code that is never executed by the kernel mapping,
but for which the toolchain nonetheless generates sframe data, and needs
to be considered valid for a PC lookup.
Additionally .init.text lies outside .text for all arches and must be
accounted for as well.
Suggested-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
arch/Kconfig | 2 +-
arch/arm64/include/asm/sections.h | 1 +
arch/arm64/include/asm/unwind_sframe.h | 47 ++++++++++++++++++++++++++
arch/arm64/kernel/vmlinux.lds.S | 2 ++
include/linux/sframe.h | 2 ++
kernel/unwind/sframe.c | 25 ++++++++++++--
6 files changed, 76 insertions(+), 3 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 8d27b3249e7a..a528f5b23647 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -503,7 +503,7 @@ config HAVE_UNWIND_USER_SFRAME
config SFRAME_VALIDATION
bool "Enable .sframe section debugging"
- depends on HAVE_UNWIND_USER_SFRAME
+ depends on UNWIND_SFRAME_LOOKUP
depends on DYNAMIC_DEBUG
help
When adding an .sframe section for a task, validate the entire
diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h
index 51b0d594239e..5edb4304f661 100644
--- a/arch/arm64/include/asm/sections.h
+++ b/arch/arm64/include/asm/sections.h
@@ -23,6 +23,7 @@ extern char __irqentry_text_start[], __irqentry_text_end[];
extern char __mmuoff_data_start[], __mmuoff_data_end[];
extern char __entry_tramp_text_start[], __entry_tramp_text_end[];
extern char __relocate_new_kernel_start[], __relocate_new_kernel_end[];
+extern char _srodatatext[], _erodatatext[];
static inline size_t entry_tramp_text_size(void)
{
diff --git a/arch/arm64/include/asm/unwind_sframe.h b/arch/arm64/include/asm/unwind_sframe.h
index 876412881196..66ebe5f38bd0 100644
--- a/arch/arm64/include/asm/unwind_sframe.h
+++ b/arch/arm64/include/asm/unwind_sframe.h
@@ -2,7 +2,54 @@
#ifndef _ASM_ARM64_UNWIND_SFRAME_H
#define _ASM_ARM64_UNWIND_SFRAME_H
+#include <linux/module.h>
+#include <linux/sframe.h>
+#include <asm/sections.h>
+
#define SFRAME_REG_SP 31
#define SFRAME_REG_FP 29
+static inline bool sframe_func_start_addr_valid(struct sframe_section *sec,
+ unsigned long func_addr)
+{
+ /* Common case for unwinding */
+ if (sec->text_start <= func_addr && func_addr < sec->text_end)
+ return true;
+
+ if (sec->sec_type != SFRAME_KERNEL)
+ return false;
+
+ /*
+ * Account for vmlinux and module code outside the normal .text section.
+ * The toolchain still generates sframe data for these functions, so
+ * sframe lookups on them should be allowed.
+ */
+ if (sec == &kernel_sfsec) {
+ if (is_kernel_inittext(func_addr))
+ return true;
+
+ /* .exit.text is retained in vmlinux on arm64. */
+ if (func_addr >= (unsigned long)__exittext_begin &&
+ func_addr < (unsigned long)__exittext_end)
+ return true;
+
+
+ /*
+ * .rodata.text is never executed from the kernel mapping, but
+ * still has sframe data
+ */
+ if (func_addr >= (unsigned long)_srodatatext &&
+ func_addr < (unsigned long)_erodatatext)
+ return true;
+ } else {
+ struct module *mod = container_of(sec, struct module,
+ arch.sframe_sec);
+ if (within_module_mem_type(func_addr, mod, MOD_INIT_TEXT))
+ return true;
+ }
+
+ return false;
+}
+#define sframe_func_start_addr_valid sframe_func_start_addr_valid
+
#endif /* _ASM_ARM64_UNWIND_SFRAME_H */
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 2964aad0362e..8c2dae6e7a86 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -213,12 +213,14 @@ SECTIONS
/* code sections that are never executed via the kernel mapping */
.rodata.text : {
+ _srodatatext = .;
TRAMP_TEXT
HIBERNATE_TEXT
KEXEC_TEXT
IDMAP_TEXT
. = ALIGN(PAGE_SIZE);
}
+ _erodatatext = .;
idmap_pg_dir = .;
. += PAGE_SIZE;
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index 27f5a66190af..ac3aa9db7d91 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -34,6 +34,8 @@ struct sframe_section {
signed char fp_off;
};
+extern struct sframe_section kernel_sfsec __ro_after_init;
+
#endif /* CONFIG_UNWIND_SFRAME_LOOKUP */
#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 70001c8e586d..99c2a39c51ce 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -21,10 +21,18 @@
#include "sframe.h"
#include "sframe_debug.h"
+#ifndef sframe_func_start_addr_valid
+static inline bool sframe_func_start_addr_valid(struct sframe_section *sec,
+ unsigned long func_addr)
+{
+ return (sec->text_start <= func_addr && func_addr < sec->text_end);
+}
+#endif
+
#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
static bool sframe_init __ro_after_init;
-static struct sframe_section kernel_sfsec __ro_after_init;
+struct sframe_section kernel_sfsec __ro_after_init;
#endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
@@ -152,7 +160,7 @@ static __always_inline int __read_fde(struct sframe_section *sec,
sizeof(struct sframe_fde_v3), Efault);
func_addr = fde_addr + _fde.func_start_off;
- if (func_addr < sec->text_start || func_addr > sec->text_end)
+ if (!sframe_func_start_addr_valid(sec, func_addr))
return -EINVAL;
fda_addr = sec->fres_start + _fde.fres_off;
@@ -636,6 +644,9 @@ static int safe_read_fde(struct sframe_section *sec,
{
int ret;
+ if (sec->sec_type == SFRAME_KERNEL)
+ return __read_fde(sec, fde_num, fde);
+
if (!user_read_access_begin((void __user *)sec->sframe_start,
sec->sframe_end - sec->sframe_start))
return -EFAULT;
@@ -651,6 +662,9 @@ static int safe_read_fre(struct sframe_section *sec,
{
int ret;
+ if (sec->sec_type == SFRAME_KERNEL)
+ return __read_fre(sec, fde, fre_addr, fre);
+
if (!user_read_access_begin((void __user *)sec->sframe_start,
sec->sframe_end - sec->sframe_start))
return -EFAULT;
@@ -665,6 +679,9 @@ static int safe_read_fre_datawords(struct sframe_section *sec,
{
int ret;
+ if (sec->sec_type == SFRAME_KERNEL)
+ return __read_fre_datawords(sec, fde, fre);
+
if (!user_read_access_begin((void __user *)sec->sframe_start,
sec->sframe_end - sec->sframe_start))
return -EFAULT;
@@ -1013,6 +1030,8 @@ void __init init_sframe_table(void)
if (WARN_ON(sframe_read_header(&kernel_sfsec)))
return;
+ if (WARN_ON(sframe_validate_section(&kernel_sfsec)))
+ return;
sframe_init = true;
}
@@ -1031,6 +1050,8 @@ void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
if (WARN_ON(sframe_read_header(&sec)))
return;
+ if (WARN_ON(sframe_validate_section(&sec)))
+ return;
mod->arch.sframe_sec = sec;
mod->arch.sframe_init = true;
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* [PATCH v5 8/8] unwind: arm64: Use sframe to unwind interrupt frames
From: Dylan Hatch @ 2026-04-28 18:36 UTC (permalink / raw)
To: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus
Cc: Dylan Hatch, Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
Add unwind_next_frame_sframe() function to unwind by sframe info if
present. Use this method at exception boundaries, falling back to
frame-pointer unwind only on failure. In such failure cases, the
stacktrace is considered unreliable.
During normal unwind, prefer frame pointer unwind (for better
performance) with sframe as a backup.
This change restores the LR behavior originally introduced in commit
c2c6b27b5aa14fa2 ("arm64: stacktrace: unwind exception boundaries"),
But later removed in commit 32ed1205682e ("arm64: stacktrace: Skip
reporting LR at exception boundaries")
This can be done because the sframe data can be used to determine
whether the LR is current for the PC value recovered from pt_regs at the
exception boundary.
Signed-off-by: Weinan Liu <wnliu@google.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
arch/arm64/include/asm/stacktrace/common.h | 6 +
arch/arm64/kernel/stacktrace.c | 246 +++++++++++++++++++--
2 files changed, 232 insertions(+), 20 deletions(-)
diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h
index 821a8fdd31af..4df68181e1b5 100644
--- a/arch/arm64/include/asm/stacktrace/common.h
+++ b/arch/arm64/include/asm/stacktrace/common.h
@@ -21,6 +21,8 @@ struct stack_info {
*
* @fp: The fp value in the frame record (or the real fp)
* @pc: The lr value in the frame record (or the real lr)
+ * @sp: The sp value at the call site of the current function.
+ * @unreliable: Stacktrace is unreliable.
*
* @stack: The stack currently being unwound.
* @stacks: An array of stacks which can be unwound.
@@ -29,7 +31,11 @@ struct stack_info {
struct unwind_state {
unsigned long fp;
unsigned long pc;
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+ unsigned long sp;
+#endif
+ bool unreliable;
struct stack_info stack;
struct stack_info *stacks;
int nr_stacks;
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 3ebcf8c53fb0..c935323f393b 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -14,6 +14,7 @@
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/stacktrace.h>
+#include <linux/sframe.h>
#include <asm/efi.h>
#include <asm/irq.h>
@@ -26,6 +27,7 @@ enum kunwind_source {
KUNWIND_SOURCE_CALLER,
KUNWIND_SOURCE_TASK,
KUNWIND_SOURCE_REGS_PC,
+ KUNWIND_SOURCE_REGS_LR,
};
union unwind_flags {
@@ -85,6 +87,9 @@ kunwind_init_from_regs(struct kunwind_state *state,
state->regs = regs;
state->common.fp = regs->regs[29];
state->common.pc = regs->pc;
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+ state->common.sp = regs->sp;
+#endif
state->source = KUNWIND_SOURCE_REGS_PC;
}
@@ -103,6 +108,9 @@ kunwind_init_from_caller(struct kunwind_state *state)
state->common.fp = (unsigned long)__builtin_frame_address(1);
state->common.pc = (unsigned long)__builtin_return_address(0);
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+ state->common.sp = (unsigned long)__builtin_frame_address(0);
+#endif
state->source = KUNWIND_SOURCE_CALLER;
}
@@ -124,6 +132,9 @@ kunwind_init_from_task(struct kunwind_state *state,
state->common.fp = thread_saved_fp(task);
state->common.pc = thread_saved_pc(task);
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+ state->common.sp = thread_saved_sp(task);
+#endif
state->source = KUNWIND_SOURCE_TASK;
}
@@ -181,7 +192,6 @@ int kunwind_next_regs_pc(struct kunwind_state *state)
state->regs = regs;
state->common.pc = regs->pc;
state->common.fp = regs->regs[29];
- state->regs = NULL;
state->source = KUNWIND_SOURCE_REGS_PC;
return 0;
}
@@ -237,6 +247,9 @@ kunwind_next_frame_record(struct kunwind_state *state)
unwind_consume_stack(&state->common, info, fp, sizeof(*record));
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+ state->common.sp = state->common.fp;
+#endif
state->common.fp = new_fp;
state->common.pc = new_pc;
state->source = KUNWIND_SOURCE_FRAME;
@@ -244,6 +257,176 @@ kunwind_next_frame_record(struct kunwind_state *state)
return 0;
}
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+
+static __always_inline struct stack_info *
+get_word(struct unwind_state *state, unsigned long *word)
+{
+ unsigned long addr = *word;
+ struct stack_info *info;
+
+ info = unwind_find_stack(state, addr, sizeof(addr));
+ if (!info)
+ return info;
+
+ *word = READ_ONCE(*(unsigned long *)addr);
+
+ return info;
+}
+
+static __always_inline int
+get_consume_word(struct unwind_state *state, unsigned long *word)
+{
+ struct stack_info *info;
+ unsigned long addr = *word;
+
+ info = get_word(state, word);
+ if (!info)
+ return -EINVAL;
+
+ unwind_consume_stack(state, info, addr, sizeof(addr));
+ return 0;
+}
+
+/*
+ * Unwind to the next frame according to sframe.
+ */
+static __always_inline int
+unwind_next_frame_sframe(struct kunwind_state *state)
+{
+ struct unwind_frame frame;
+ unsigned long cfa, fp, ra;
+ enum kunwind_source source = KUNWIND_SOURCE_FRAME;
+ struct pt_regs *regs = state->regs;
+
+ int err;
+
+ /* FP/SP alignment 8 bytes */
+ if (state->common.fp & 0x7 || state->common.sp & 0x7)
+ return -EINVAL;
+
+ /*
+ * Most/all outermost functions are not visible to sframe. So, check for
+ * a meta frame record if the sframe lookup fails.
+ */
+ err = sframe_find_kernel(state->common.pc, &frame);
+ if (err)
+ return kunwind_next_frame_record_meta(state);
+
+ if (frame.outermost)
+ return -ENOENT;
+
+ /* Get the Canonical Frame Address (CFA) */
+ switch (frame.cfa.rule) {
+ case UNWIND_CFA_RULE_SP_OFFSET:
+ cfa = state->common.sp;
+ break;
+ case UNWIND_CFA_RULE_FP_OFFSET:
+ if (state->common.fp < state->common.sp)
+ return -EINVAL;
+ cfa = state->common.fp;
+ break;
+ case UNWIND_CFA_RULE_REG_OFFSET:
+ case UNWIND_CFA_RULE_REG_OFFSET_DEREF:
+ /* regs only available in topmost/interrupt frame */
+ if (!regs || frame.cfa.regnum > 30)
+ return -EINVAL;
+ cfa = regs->regs[frame.cfa.regnum];
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+ }
+ cfa += frame.cfa.offset;
+
+ /*
+ * CFA typically points to a higher address than RA or FP, so don't
+ * consume from the stack when we read it.
+ */
+ if (frame.cfa.rule & UNWIND_RULE_DEREF &&
+ !get_word(&state->common, &cfa))
+ return -EINVAL;
+
+ /* CFA alignment 8 bytes */
+ if (cfa & 0x7)
+ return -EINVAL;
+
+ /* Get the Return Address (RA) */
+ switch (frame.ra.rule) {
+ case UNWIND_RULE_RETAIN:
+ /* regs only available in topmost/interrupt frame */
+ if (!regs)
+ return -EINVAL;
+ ra = regs->regs[30];
+ source = KUNWIND_SOURCE_REGS_LR;
+ break;
+ /* UNWIND_USER_RULE_CFA_OFFSET not implemented on purpose */
+ case UNWIND_RULE_CFA_OFFSET_DEREF:
+ ra = cfa + frame.ra.offset;
+ break;
+ case UNWIND_RULE_REG_OFFSET:
+ case UNWIND_RULE_REG_OFFSET_DEREF:
+ /* regs only available in topmost/interrupt frame */
+ if (!regs)
+ return -EINVAL;
+ ra = regs->regs[frame.cfa.regnum];
+ ra += frame.ra.offset;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+ }
+
+ /* Get the Frame Pointer (FP) */
+ switch (frame.fp.rule) {
+ case UNWIND_RULE_RETAIN:
+ fp = state->common.fp;
+ break;
+ /* UNWIND_USER_RULE_CFA_OFFSET not implemented on purpose */
+ case UNWIND_RULE_CFA_OFFSET_DEREF:
+ fp = cfa + frame.fp.offset;
+ break;
+ case UNWIND_RULE_REG_OFFSET:
+ case UNWIND_RULE_REG_OFFSET_DEREF:
+ /* regs only available in topmost/interrupt frame */
+ if (!regs)
+ return -EINVAL;
+ fp = regs->regs[frame.fp.regnum];
+ fp += frame.fp.offset;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+ }
+
+ /*
+ * Consume RA and FP from the stack. The frame record puts FP at a lower
+ * address than RA, so we always read FP first.
+ */
+ if (frame.fp.rule & UNWIND_RULE_DEREF &&
+ !get_word(&state->common, &fp))
+ return -EINVAL;
+
+ if (frame.ra.rule & UNWIND_RULE_DEREF &&
+ get_consume_word(&state->common, &ra))
+ return -EINVAL;
+
+ state->common.pc = ra;
+ state->common.sp = cfa;
+ state->common.fp = fp;
+
+ state->source = source;
+
+ return 0;
+}
+
+#else /* !CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
+
+static __always_inline int
+unwind_next_frame_sframe(struct kunwind_state *state) { return -EINVAL; }
+
+#endif /* !CONFIG_HAVE_UNWIND_KERNEL_SFRAME*/
+
/*
* Unwind from one frame record (A) to the next frame record (B).
*
@@ -259,12 +442,25 @@ kunwind_next(struct kunwind_state *state)
state->flags.all = 0;
switch (state->source) {
+ case KUNWIND_SOURCE_REGS_PC:
+ err = unwind_next_frame_sframe(state);
+
+ if (err && err != -ENOENT) {
+ /* Fallback to FP based unwinder */
+ err = kunwind_next_frame_record(state);
+ state->common.unreliable = true;
+ }
+ state->regs = NULL;
+ break;
case KUNWIND_SOURCE_FRAME:
case KUNWIND_SOURCE_CALLER:
case KUNWIND_SOURCE_TASK:
- case KUNWIND_SOURCE_REGS_PC:
+ case KUNWIND_SOURCE_REGS_LR:
err = kunwind_next_frame_record(state);
+ if (err && err != -ENOENT)
+ err = unwind_next_frame_sframe(state);
break;
+
default:
err = -EINVAL;
}
@@ -350,6 +546,9 @@ kunwind_stack_walk(kunwind_consume_fn consume_state,
.common = {
.stacks = stacks,
.nr_stacks = ARRAY_SIZE(stacks),
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+ .sp = 0,
+#endif
},
};
@@ -390,34 +589,40 @@ noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry,
kunwind_stack_walk(arch_kunwind_consume_entry, &data, task, regs);
}
+struct kunwind_reliable_consume_entry_data {
+ stack_trace_consume_fn consume_entry;
+ void *cookie;
+ bool unreliable;
+};
+
static __always_inline bool
-arch_reliable_kunwind_consume_entry(const struct kunwind_state *state, void *cookie)
+arch_kunwind_reliable_consume_entry(const struct kunwind_state *state, void *cookie)
{
- /*
- * At an exception boundary we can reliably consume the saved PC. We do
- * not know whether the LR was live when the exception was taken, and
- * so we cannot perform the next unwind step reliably.
- *
- * All that matters is whether the *entire* unwind is reliable, so give
- * up as soon as we hit an exception boundary.
- */
- if (state->source == KUNWIND_SOURCE_REGS_PC)
- return false;
+ struct kunwind_reliable_consume_entry_data *data = cookie;
- return arch_kunwind_consume_entry(state, cookie);
+ if (state->common.unreliable) {
+ data->unreliable = true;
+ return false;
+ }
+ return data->consume_entry(data->cookie, state->common.pc);
}
-noinline noinstr int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
- void *cookie,
- struct task_struct *task)
+noinline notrace int arch_stack_walk_reliable(
+ stack_trace_consume_fn consume_entry,
+ void *cookie, struct task_struct *task)
{
- struct kunwind_consume_entry_data data = {
+ struct kunwind_reliable_consume_entry_data data = {
.consume_entry = consume_entry,
.cookie = cookie,
+ .unreliable = false,
};
- return kunwind_stack_walk(arch_reliable_kunwind_consume_entry, &data,
- task, NULL);
+ kunwind_stack_walk(arch_kunwind_reliable_consume_entry, &data, task, NULL);
+
+ if (data.unreliable)
+ return -EINVAL;
+
+ return 0;
}
struct bpf_unwind_consume_entry_data {
@@ -452,6 +657,7 @@ static const char *state_source_string(const struct kunwind_state *state)
case KUNWIND_SOURCE_CALLER: return "C";
case KUNWIND_SOURCE_TASK: return "T";
case KUNWIND_SOURCE_REGS_PC: return "P";
+ case KUNWIND_SOURCE_REGS_LR: return "L";
default: return "U";
}
}
--
2.54.0.545.g6539524ca2-goog
^ permalink raw reply related
* Re: [PATCH 41/48] objtool/klp: Rewrite symbol correlation algorithm
From: Song Liu @ 2026-04-28 20:50 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, live-patching, Peter Zijlstra, Joe Lawrence,
Miroslav Benes, Petr Mladek
In-Reply-To: <abm7sbrlshe23ccholc5q67idnvuackxfy34thnpvyeiglafwe@cdtxtdi3zenv>
On Tue, Apr 28, 2026 at 5:23 PM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
[...]
> > Also a few nitpicks below.
> >
> > > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> > > ---
> > [...]
> > > +static struct symbol *find_twin(struct elfs *e, struct symbol *sym1)
> > > +{
> > > + struct symbol *name_last = NULL, *scope_last = NULL,
> > > + *file_last = NULL, *csum_last = NULL;
> > > + unsigned int name_orig = 0, name_patched = 0;
> > > + unsigned int scope_orig = 0, scope_patched = 0;
> > > + unsigned int file_orig = 0, file_patched = 0;
> > > + unsigned int csum_orig = 0, csum_patched = 0;
> > > + struct symbol *sym2, *match = NULL;
> > > +
> > > + /* Count orig candidates */
> > > + for_each_sym_by_demangled_name(e->orig, sym1->demangled_name, sym2) {
> > > + if (sym2->twin || sym1->type != sym2->type || dont_correlate(sym2) ||
> > > + (!maybe_same_file(sym1, sym2)))
> > > continue;
> > >
> > > - count++;
> > > - result = sym2;
> > > + /* Level 1: name match (widest filter) */
> > > + name_orig++;
> > > +
> > > + /* Level 2: scope (scope changes allowed) */
> > > + if (is_tu_local_sym(sym1) != is_tu_local_sym(sym2))
> >
> > is_tu_local_sym(sym1) is called many times, shall we add a variable
> > for it?
>
> Unless it's actually a performance issue I'd prefer not to add yet
> another bit to struct symbol.
We don't need to add it to struct symbol, a local variable for sym1
will be good. No need for sym2.
IOW, we have something like
bool sym1_is_local = is_tu_local_sym(sym1);
...
if (sym1_is_local != is_tu_local_sym(sym2))
...
Thanks,
Song
^ permalink raw reply
* [PATCH v4 0/6] kselftests: livepatch: Adapt tests to be executed on 4.12 kernels
From: Marcos Paulo de Souza @ 2026-04-29 14:35 UTC (permalink / raw)
To: Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek,
Joe Lawrence, Shuah Khan
Cc: live-patching, linux-kselftest, linux-kernel,
Marcos Paulo de Souza
This is the third version of the patchset, now with far less changes. There
are still somethings that I would like to work next, like adapting the
newest test introduced in the last submsision, but this is something for
a new iteration.
Original cover-letter:
These patches don't really change how the patches are run, just skip
some tests on kernels that don't support a feature (like kprobe and
livepatched living together) or when a livepatch sysfs attribute is
missing.
These patches are based on printk/for-next branch.
Please review! Thanks!
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
Changes in v4:
- Patch 5 was changed in order to address a comment made by Sashiko, where
subsequent tests rewrite the variables that contain the modules being loaded.
- Link to v3: https://patch.msgid.link/20260427-lp-tests-old-fixes-v3-0-ccf3c90f744c@suse.com
Changes in v3:
- Patch 1 was changed to reorganize the ifdeffery to handle multiple archs syscall wrapper (Miroslav)
- Patch 3 was changed to rework the commit message and to address function naming (Joe)
- Patches 4, 5 and 6 where had the commit messages to include the kernel version where
the given sysfs attributes were included (Petr Mladek)
- Link to v2: https://patch.msgid.link/20260413-lp-tests-old-fixes-v2-0-367c7cb5006f@suse.com
Changes in v2:
- Patch descriptions were changed to remove "test-X", since it was polluting the commit subjects (Miroslav Benes)
- Patch 8 was dropped since it was checking for a message from an out-of-tree patch. (Petr Mladek)
- Patch 3 was dropped as should be treated as expected failure for older kernels. (Petr Mladek)
- Patch 2 was changed to use y/n instead of 1/0, since it's more natural to use it.
- Patch 1 was changed to handle ppc and loongson, and error out if dealing with a different architecture that sets
CONFIG_ARCH_HAS_SYSCALL_WRAPPER and haven't changed the test to include the proper wrapper prefix.
- Patch 4 was changed to invert the return of the bash function to return 1 in failure, like
a normal bash function (Joe Lawrence)
- Patches 5, 6 an 7 were changed to not split the tests, but to only run the tests
when the attribute were present (Miroslav Benes)
- Link to v1: https://patch.msgid.link/20260313-lp-tests-old-fixes-v1-0-71ac6dfb3253@suse.com
---
Marcos Paulo de Souza (6):
selftests: livepatch: Check for ARCH_HAS_SYSCALL_WRAPPER config
selftests: livepatch: Replace true/false module parameter by y/n
selftests: livepatch: Introduce does_sysfs_exist function
selftests: livepatch: Check if patched sysfs attribute exists
selftests: livepatch: Check if replace sysfs attribute exists
selftests: livepatch: Check if stack_order sysfs attribute exists
tools/testing/selftests/livepatch/functions.sh | 10 +
tools/testing/selftests/livepatch/test-kprobe.sh | 8 +-
tools/testing/selftests/livepatch/test-sysfs.sh | 222 +++++++++++----------
.../livepatch/test_modules/test_klp_syscall.c | 27 ++-
4 files changed, 155 insertions(+), 112 deletions(-)
---
base-commit: b8e6ad22f78aa279dece2f86efe6429953d36452
change-id: 20260309-lp-tests-old-fixes-f955abc8ec27
Best regards,
--
Marcos Paulo de Souza <mpdesouza@suse.com>
^ permalink raw reply
* [PATCH v4 1/6] selftests: livepatch: Check for ARCH_HAS_SYSCALL_WRAPPER config
From: Marcos Paulo de Souza @ 2026-04-29 14:35 UTC (permalink / raw)
To: Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek,
Joe Lawrence, Shuah Khan
Cc: live-patching, linux-kselftest, linux-kernel,
Marcos Paulo de Souza
In-Reply-To: <20260429-lp-tests-old-fixes-v4-0-59b9741989d0@suse.com>
Older kernels that lack CONFIG_ARCH_HAS_SYSCALL_WRAPPER config don't
have any prefixes for their syscalls. The same applies to current
powerpc and loongarch, covering all currently supported architectures
that support livepatch.
The other supported architectures have specific prefixes, so error out
when a new architecture adds livepatch support with wrappers but didn't
update the test to include it.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
.../livepatch/test_modules/test_klp_syscall.c | 27 +++++++++++++++-------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c b/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c
index dd802783ea84..0630ffd9d9a1 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c
@@ -12,15 +12,26 @@
#include <linux/slab.h>
#include <linux/livepatch.h>
-#if defined(__x86_64__)
-#define FN_PREFIX __x64_
-#elif defined(__s390x__)
-#define FN_PREFIX __s390x_
-#elif defined(__aarch64__)
-#define FN_PREFIX __arm64_
+/*
+ * Before CONFIG_ARCH_HAS_SYSCALL_WRAPPER was introduced there were no
+ * prefixes for system calls.
+ * powerpc set this config based on configs, so it can be enabled or not.
+ */
+#if defined(CONFIG_ARCH_HAS_SYSCALL_WRAPPER)
+ #if defined(__x86_64__)
+ #define FN_PREFIX __x64_
+ #elif defined(__s390x__)
+ #define FN_PREFIX __s390x_
+ #elif defined(__aarch64__)
+ #define FN_PREFIX __arm64_
+ #elif defined(__powerpc__)
+ #define FN_PREFIX
+ #else
+ #error "Missing syscall wrapper for the given architecture."
+ #endif
#else
-/* powerpc does not select ARCH_HAS_SYSCALL_WRAPPER */
-#define FN_PREFIX
+ /* Do not set a prefix for architectures that do not enable wrappers. */
+ #define FN_PREFIX
#endif
/* Protects klp_pids */
--
2.54.0
^ permalink raw reply related
* [PATCH v4 2/6] selftests: livepatch: Replace true/false module parameter by y/n
From: Marcos Paulo de Souza @ 2026-04-29 14:35 UTC (permalink / raw)
To: Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek,
Joe Lawrence, Shuah Khan
Cc: live-patching, linux-kselftest, linux-kernel,
Marcos Paulo de Souza
In-Reply-To: <20260429-lp-tests-old-fixes-v4-0-59b9741989d0@suse.com>
Older kernels don't support true/false for boolean module parameters
because they lack commit 0d6ea3ac94ca
("lib/kstrtox.c: add "false"/"true" support to kstrtobool()"). Replace
true/false by y/n so the test module can be loaded on older kernels.
No functional changes.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
tools/testing/selftests/livepatch/test-kprobe.sh | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/livepatch/test-kprobe.sh b/tools/testing/selftests/livepatch/test-kprobe.sh
index b67dfad03d97..7ced4082cff3 100755
--- a/tools/testing/selftests/livepatch/test-kprobe.sh
+++ b/tools/testing/selftests/livepatch/test-kprobe.sh
@@ -20,11 +20,11 @@ start_test "livepatch interaction with kprobed function with post_handler"
echo 1 > "$SYSFS_KPROBES_DIR/enabled"
-load_mod $MOD_KPROBE has_post_handler=true
+load_mod $MOD_KPROBE has_post_handler=y
load_failing_mod $MOD_LIVEPATCH
unload_mod $MOD_KPROBE
-check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=true
+check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=y
% insmod test_modules/$MOD_LIVEPATCH.ko
livepatch: enabling patch '$MOD_LIVEPATCH'
livepatch: '$MOD_LIVEPATCH': initializing patching transition
@@ -39,14 +39,14 @@ insmod: ERROR: could not insert module test_modules/$MOD_LIVEPATCH.ko: Device or
start_test "livepatch interaction with kprobed function without post_handler"
-load_mod $MOD_KPROBE has_post_handler=false
+load_mod $MOD_KPROBE has_post_handler=n
load_lp $MOD_LIVEPATCH
unload_mod $MOD_KPROBE
disable_lp $MOD_LIVEPATCH
unload_lp $MOD_LIVEPATCH
-check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=false
+check_result "% insmod test_modules/test_klp_kprobe.ko has_post_handler=n
% insmod test_modules/$MOD_LIVEPATCH.ko
livepatch: enabling patch '$MOD_LIVEPATCH'
livepatch: '$MOD_LIVEPATCH': initializing patching transition
--
2.54.0
^ permalink raw reply related
* [PATCH v4 3/6] selftests: livepatch: Introduce does_sysfs_exist function
From: Marcos Paulo de Souza @ 2026-04-29 14:35 UTC (permalink / raw)
To: Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek,
Joe Lawrence, Shuah Khan
Cc: live-patching, linux-kselftest, linux-kernel,
Marcos Paulo de Souza
In-Reply-To: <20260429-lp-tests-old-fixes-v4-0-59b9741989d0@suse.com>
Returns true if the livepatch sysfs attribute exists, and false otherwise.
This new function will be used in the next patches.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
tools/testing/selftests/livepatch/functions.sh | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 8ec0cb64ad94..2bc50271729c 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -339,6 +339,16 @@ function check_result {
fi
}
+# does_sysfs_exist(modname, attr) - check sysfs attribute existence
+# modname - livepatch module creating the sysfs interface
+# attr - attribute name to be checked
+function does_sysfs_exist() {
+ local mod="$1"; shift
+ local attr="$1"; shift
+
+ [[ -f "$SYSFS_KLP_DIR/$mod/$attr" ]]
+}
+
# check_sysfs_rights(modname, rel_path, expected_rights) - check sysfs
# path permissions
# modname - livepatch module creating the sysfs interface
--
2.54.0
^ permalink raw reply related
* [PATCH v4 4/6] selftests: livepatch: Check if patched sysfs attribute exists
From: Marcos Paulo de Souza @ 2026-04-29 14:35 UTC (permalink / raw)
To: Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek,
Joe Lawrence, Shuah Khan
Cc: live-patching, linux-kselftest, linux-kernel,
Marcos Paulo de Souza
In-Reply-To: <20260429-lp-tests-old-fixes-v4-0-59b9741989d0@suse.com>
The commit bb26cfd9e77e
("livepatch: add sysfs entry "patched" for each klp_object") was merged
in v6.1, introducing a new sysfs attribute.
In order to run the selftests on older kernels, check if given kernel
has support for the attribute. If the attribute is not supported, skip
the checks.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
tools/testing/selftests/livepatch/test-sysfs.sh | 38 +++++++++++++++----------
1 file changed, 23 insertions(+), 15 deletions(-)
diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
index 58fe1d96997c..394cf3ff99cd 100755
--- a/tools/testing/selftests/livepatch/test-sysfs.sh
+++ b/tools/testing/selftests/livepatch/test-sysfs.sh
@@ -8,6 +8,8 @@ MOD_LIVEPATCH=test_klp_livepatch
MOD_LIVEPATCH2=test_klp_callbacks_demo
MOD_LIVEPATCH3=test_klp_syscall
+HAS_PATCH_ATTR=0
+
setup_config
# - load a livepatch and verifies the sysfs entries work as expected
@@ -25,8 +27,12 @@ check_sysfs_rights "$MOD_LIVEPATCH" "stack_order" "-r--r--r--"
check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
check_sysfs_rights "$MOD_LIVEPATCH" "transition" "-r--r--r--"
check_sysfs_value "$MOD_LIVEPATCH" "transition" "0"
-check_sysfs_rights "$MOD_LIVEPATCH" "vmlinux/patched" "-r--r--r--"
-check_sysfs_value "$MOD_LIVEPATCH" "vmlinux/patched" "1"
+
+if does_sysfs_exist "$MOD_LIVEPATCH/vmlinux" "patched"; then
+ check_sysfs_rights "$MOD_LIVEPATCH" "vmlinux/patched" "-r--r--r--"
+ check_sysfs_value "$MOD_LIVEPATCH" "vmlinux/patched" "1"
+ HAS_PATCH_ATTR=1
+fi
disable_lp $MOD_LIVEPATCH
@@ -45,23 +51,24 @@ livepatch: '$MOD_LIVEPATCH': completing unpatching transition
livepatch: '$MOD_LIVEPATCH': unpatching complete
% rmmod $MOD_LIVEPATCH"
-start_test "sysfs test object/patched"
+if [[ "$HAS_PATCH_ATTR" == "1" ]]; then
+ start_test "sysfs test object/patched"
-MOD_LIVEPATCH=test_klp_callbacks_demo
-MOD_TARGET=test_klp_callbacks_mod
-load_lp $MOD_LIVEPATCH
+ MOD_LIVEPATCH=test_klp_callbacks_demo
+ MOD_TARGET=test_klp_callbacks_mod
+ load_lp $MOD_LIVEPATCH
-# check the "patch" file changes as target module loads/unloads
-check_sysfs_value "$MOD_LIVEPATCH" "$MOD_TARGET/patched" "0"
-load_mod $MOD_TARGET
-check_sysfs_value "$MOD_LIVEPATCH" "$MOD_TARGET/patched" "1"
-unload_mod $MOD_TARGET
-check_sysfs_value "$MOD_LIVEPATCH" "$MOD_TARGET/patched" "0"
+ # check the "patch" file changes as target module loads/unloads
+ check_sysfs_value "$MOD_LIVEPATCH" "$MOD_TARGET/patched" "0"
+ load_mod $MOD_TARGET
+ check_sysfs_value "$MOD_LIVEPATCH" "$MOD_TARGET/patched" "1"
+ unload_mod $MOD_TARGET
+ check_sysfs_value "$MOD_LIVEPATCH" "$MOD_TARGET/patched" "0"
-disable_lp $MOD_LIVEPATCH
-unload_lp $MOD_LIVEPATCH
+ disable_lp $MOD_LIVEPATCH
+ unload_lp $MOD_LIVEPATCH
-check_result "% insmod test_modules/test_klp_callbacks_demo.ko
+ check_result "% insmod test_modules/test_klp_callbacks_demo.ko
livepatch: enabling patch 'test_klp_callbacks_demo'
livepatch: 'test_klp_callbacks_demo': initializing patching transition
test_klp_callbacks_demo: pre_patch_callback: vmlinux
@@ -87,6 +94,7 @@ livepatch: 'test_klp_callbacks_demo': completing unpatching transition
test_klp_callbacks_demo: post_unpatch_callback: vmlinux
livepatch: 'test_klp_callbacks_demo': unpatching complete
% rmmod test_klp_callbacks_demo"
+fi
start_test "sysfs test replace enabled"
--
2.54.0
^ permalink raw reply related
* [PATCH v4 5/6] selftests: livepatch: Check if replace sysfs attribute exists
From: Marcos Paulo de Souza @ 2026-04-29 14:35 UTC (permalink / raw)
To: Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek,
Joe Lawrence, Shuah Khan
Cc: live-patching, linux-kselftest, linux-kernel,
Marcos Paulo de Souza
In-Reply-To: <20260429-lp-tests-old-fixes-v4-0-59b9741989d0@suse.com>
The commit adb68ed26a3e ("livepatch: Add "replace" sysfs attribute"),
merged in v6.11, introduced a new sysfs attribute.
In order to run the selftests on older kernels, check if given kernel
has support for the attribute. If the attribute is not supported, skip
the checks.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
tools/testing/selftests/livepatch/test-sysfs.sh | 39 +++++++++++++++----------
1 file changed, 23 insertions(+), 16 deletions(-)
diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
index 394cf3ff99cd..744c612a90d3 100755
--- a/tools/testing/selftests/livepatch/test-sysfs.sh
+++ b/tools/testing/selftests/livepatch/test-sysfs.sh
@@ -9,6 +9,7 @@ MOD_LIVEPATCH2=test_klp_callbacks_demo
MOD_LIVEPATCH3=test_klp_syscall
HAS_PATCH_ATTR=0
+HAS_REPLACE_ATTR=0
setup_config
@@ -22,7 +23,6 @@ check_sysfs_rights "$MOD_LIVEPATCH" "" "drwxr-xr-x"
check_sysfs_rights "$MOD_LIVEPATCH" "enabled" "-rw-r--r--"
check_sysfs_value "$MOD_LIVEPATCH" "enabled" "1"
check_sysfs_rights "$MOD_LIVEPATCH" "force" "--w-------"
-check_sysfs_rights "$MOD_LIVEPATCH" "replace" "-r--r--r--"
check_sysfs_rights "$MOD_LIVEPATCH" "stack_order" "-r--r--r--"
check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
check_sysfs_rights "$MOD_LIVEPATCH" "transition" "-r--r--r--"
@@ -34,6 +34,11 @@ if does_sysfs_exist "$MOD_LIVEPATCH/vmlinux" "patched"; then
HAS_PATCH_ATTR=1
fi
+if does_sysfs_exist "$MOD_LIVEPATCH" "replace"; then
+ check_sysfs_rights "$MOD_LIVEPATCH" "replace" "-r--r--r--"
+ HAS_REPLACE_ATTR=1
+fi
+
disable_lp $MOD_LIVEPATCH
unload_lp $MOD_LIVEPATCH
@@ -96,18 +101,19 @@ livepatch: 'test_klp_callbacks_demo': unpatching complete
% rmmod test_klp_callbacks_demo"
fi
-start_test "sysfs test replace enabled"
+if [[ "$HAS_REPLACE_ATTR" == "1" ]]; then
+ start_test "sysfs test replace enabled"
-MOD_LIVEPATCH=test_klp_atomic_replace
-load_lp $MOD_LIVEPATCH replace=1
+ MOD_LIVEPATCH=test_klp_atomic_replace
+ load_lp $MOD_LIVEPATCH replace=1
-check_sysfs_rights "$MOD_LIVEPATCH" "replace" "-r--r--r--"
-check_sysfs_value "$MOD_LIVEPATCH" "replace" "1"
+ check_sysfs_rights "$MOD_LIVEPATCH" "replace" "-r--r--r--"
+ check_sysfs_value "$MOD_LIVEPATCH" "replace" "1"
-disable_lp $MOD_LIVEPATCH
-unload_lp $MOD_LIVEPATCH
+ disable_lp $MOD_LIVEPATCH
+ unload_lp $MOD_LIVEPATCH
-check_result "% insmod test_modules/$MOD_LIVEPATCH.ko replace=1
+ check_result "% insmod test_modules/$MOD_LIVEPATCH.ko replace=1
livepatch: enabling patch '$MOD_LIVEPATCH'
livepatch: '$MOD_LIVEPATCH': initializing patching transition
livepatch: '$MOD_LIVEPATCH': starting patching transition
@@ -120,17 +126,17 @@ livepatch: '$MOD_LIVEPATCH': completing unpatching transition
livepatch: '$MOD_LIVEPATCH': unpatching complete
% rmmod $MOD_LIVEPATCH"
-start_test "sysfs test replace disabled"
+ start_test "sysfs test replace disabled"
-load_lp $MOD_LIVEPATCH replace=0
+ load_lp $MOD_LIVEPATCH replace=0
-check_sysfs_rights "$MOD_LIVEPATCH" "replace" "-r--r--r--"
-check_sysfs_value "$MOD_LIVEPATCH" "replace" "0"
+ check_sysfs_rights "$MOD_LIVEPATCH" "replace" "-r--r--r--"
+ check_sysfs_value "$MOD_LIVEPATCH" "replace" "0"
-disable_lp $MOD_LIVEPATCH
-unload_lp $MOD_LIVEPATCH
+ disable_lp $MOD_LIVEPATCH
+ unload_lp $MOD_LIVEPATCH
-check_result "% insmod test_modules/$MOD_LIVEPATCH.ko replace=0
+ check_result "% insmod test_modules/$MOD_LIVEPATCH.ko replace=0
livepatch: enabling patch '$MOD_LIVEPATCH'
livepatch: '$MOD_LIVEPATCH': initializing patching transition
livepatch: '$MOD_LIVEPATCH': starting patching transition
@@ -142,6 +148,7 @@ livepatch: '$MOD_LIVEPATCH': starting unpatching transition
livepatch: '$MOD_LIVEPATCH': completing unpatching transition
livepatch: '$MOD_LIVEPATCH': unpatching complete
% rmmod $MOD_LIVEPATCH"
+fi
start_test "sysfs test stack_order value"
--
2.54.0
^ permalink raw reply related
* [PATCH v4 6/6] selftests: livepatch: Check if stack_order sysfs attribute exists
From: Marcos Paulo de Souza @ 2026-04-29 14:35 UTC (permalink / raw)
To: Josh Poimboeuf, Jiri Kosina, Miroslav Benes, Petr Mladek,
Joe Lawrence, Shuah Khan
Cc: live-patching, linux-kselftest, linux-kernel,
Marcos Paulo de Souza
In-Reply-To: <20260429-lp-tests-old-fixes-v4-0-59b9741989d0@suse.com>
The commit 3dae09de4061 ("livepatch: Add stack_order sysfs attribute"),
merged in v6.14, introduced a new sysfs attribute.
In order to run the selftests on older kernels, check if given kernel
has support for the attribute. If the attribute is not supported, skip
the checks.
Moving the test up since the other checks change the default values
for MOD_LIVEPATCH and other variables.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
tools/testing/selftests/livepatch/test-sysfs.sh | 145 +++++++++++++-----------
1 file changed, 76 insertions(+), 69 deletions(-)
diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
index 744c612a90d3..4185e2f489f3 100755
--- a/tools/testing/selftests/livepatch/test-sysfs.sh
+++ b/tools/testing/selftests/livepatch/test-sysfs.sh
@@ -10,6 +10,7 @@ MOD_LIVEPATCH3=test_klp_syscall
HAS_PATCH_ATTR=0
HAS_REPLACE_ATTR=0
+HAS_STACK_ORDER_ATTR=0
setup_config
@@ -23,8 +24,6 @@ check_sysfs_rights "$MOD_LIVEPATCH" "" "drwxr-xr-x"
check_sysfs_rights "$MOD_LIVEPATCH" "enabled" "-rw-r--r--"
check_sysfs_value "$MOD_LIVEPATCH" "enabled" "1"
check_sysfs_rights "$MOD_LIVEPATCH" "force" "--w-------"
-check_sysfs_rights "$MOD_LIVEPATCH" "stack_order" "-r--r--r--"
-check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
check_sysfs_rights "$MOD_LIVEPATCH" "transition" "-r--r--r--"
check_sysfs_value "$MOD_LIVEPATCH" "transition" "0"
@@ -39,6 +38,12 @@ if does_sysfs_exist "$MOD_LIVEPATCH" "replace"; then
HAS_REPLACE_ATTR=1
fi
+if does_sysfs_exist "$MOD_LIVEPATCH" "stack_order"; then
+ check_sysfs_rights "$MOD_LIVEPATCH" "stack_order" "-r--r--r--"
+ check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
+ HAS_STACK_ORDER_ATTR=1
+fi
+
disable_lp $MOD_LIVEPATCH
unload_lp $MOD_LIVEPATCH
@@ -56,6 +61,75 @@ livepatch: '$MOD_LIVEPATCH': completing unpatching transition
livepatch: '$MOD_LIVEPATCH': unpatching complete
% rmmod $MOD_LIVEPATCH"
+if [[ "$HAS_STACK_ORDER_ATTR" == "1" ]]; then
+ start_test "sysfs test stack_order value"
+
+ load_lp $MOD_LIVEPATCH
+
+ check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
+
+ load_lp $MOD_LIVEPATCH2
+
+ check_sysfs_value "$MOD_LIVEPATCH2" "stack_order" "2"
+
+ load_lp $MOD_LIVEPATCH3
+
+ check_sysfs_value "$MOD_LIVEPATCH3" "stack_order" "3"
+
+ disable_lp $MOD_LIVEPATCH2
+ unload_lp $MOD_LIVEPATCH2
+
+ check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
+ check_sysfs_value "$MOD_LIVEPATCH3" "stack_order" "2"
+
+ disable_lp $MOD_LIVEPATCH3
+ unload_lp $MOD_LIVEPATCH3
+
+ disable_lp $MOD_LIVEPATCH
+ unload_lp $MOD_LIVEPATCH
+
+ check_result "% insmod test_modules/$MOD_LIVEPATCH.ko
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+livepatch: '$MOD_LIVEPATCH': patching complete
+% insmod test_modules/$MOD_LIVEPATCH2.ko
+livepatch: enabling patch '$MOD_LIVEPATCH2'
+livepatch: '$MOD_LIVEPATCH2': initializing patching transition
+$MOD_LIVEPATCH2: pre_patch_callback: vmlinux
+livepatch: '$MOD_LIVEPATCH2': starting patching transition
+livepatch: '$MOD_LIVEPATCH2': completing patching transition
+$MOD_LIVEPATCH2: post_patch_callback: vmlinux
+livepatch: '$MOD_LIVEPATCH2': patching complete
+% insmod test_modules/$MOD_LIVEPATCH3.ko
+livepatch: enabling patch '$MOD_LIVEPATCH3'
+livepatch: '$MOD_LIVEPATCH3': initializing patching transition
+livepatch: '$MOD_LIVEPATCH3': starting patching transition
+livepatch: '$MOD_LIVEPATCH3': completing patching transition
+livepatch: '$MOD_LIVEPATCH3': patching complete
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
+livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
+$MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
+livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH2': completing unpatching transition
+$MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
+livepatch: '$MOD_LIVEPATCH2': unpatching complete
+% rmmod $MOD_LIVEPATCH2
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH3/enabled
+livepatch: '$MOD_LIVEPATCH3': initializing unpatching transition
+livepatch: '$MOD_LIVEPATCH3': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH3': completing unpatching transition
+livepatch: '$MOD_LIVEPATCH3': unpatching complete
+% rmmod $MOD_LIVEPATCH3
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
+livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
+livepatch: '$MOD_LIVEPATCH': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH': completing unpatching transition
+livepatch: '$MOD_LIVEPATCH': unpatching complete
+% rmmod $MOD_LIVEPATCH"
+fi
+
if [[ "$HAS_PATCH_ATTR" == "1" ]]; then
start_test "sysfs test object/patched"
@@ -150,71 +224,4 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete
% rmmod $MOD_LIVEPATCH"
fi
-start_test "sysfs test stack_order value"
-
-load_lp $MOD_LIVEPATCH
-
-check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
-
-load_lp $MOD_LIVEPATCH2
-
-check_sysfs_value "$MOD_LIVEPATCH2" "stack_order" "2"
-
-load_lp $MOD_LIVEPATCH3
-
-check_sysfs_value "$MOD_LIVEPATCH3" "stack_order" "3"
-
-disable_lp $MOD_LIVEPATCH2
-unload_lp $MOD_LIVEPATCH2
-
-check_sysfs_value "$MOD_LIVEPATCH" "stack_order" "1"
-check_sysfs_value "$MOD_LIVEPATCH3" "stack_order" "2"
-
-disable_lp $MOD_LIVEPATCH3
-unload_lp $MOD_LIVEPATCH3
-
-disable_lp $MOD_LIVEPATCH
-unload_lp $MOD_LIVEPATCH
-
-check_result "% insmod test_modules/$MOD_LIVEPATCH.ko
-livepatch: enabling patch '$MOD_LIVEPATCH'
-livepatch: '$MOD_LIVEPATCH': initializing patching transition
-livepatch: '$MOD_LIVEPATCH': starting patching transition
-livepatch: '$MOD_LIVEPATCH': completing patching transition
-livepatch: '$MOD_LIVEPATCH': patching complete
-% insmod test_modules/$MOD_LIVEPATCH2.ko
-livepatch: enabling patch '$MOD_LIVEPATCH2'
-livepatch: '$MOD_LIVEPATCH2': initializing patching transition
-$MOD_LIVEPATCH2: pre_patch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': starting patching transition
-livepatch: '$MOD_LIVEPATCH2': completing patching transition
-$MOD_LIVEPATCH2: post_patch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': patching complete
-% insmod test_modules/$MOD_LIVEPATCH3.ko
-livepatch: enabling patch '$MOD_LIVEPATCH3'
-livepatch: '$MOD_LIVEPATCH3': initializing patching transition
-livepatch: '$MOD_LIVEPATCH3': starting patching transition
-livepatch: '$MOD_LIVEPATCH3': completing patching transition
-livepatch: '$MOD_LIVEPATCH3': patching complete
-% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
-livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
-$MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
-livepatch: '$MOD_LIVEPATCH2': completing unpatching transition
-$MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': unpatching complete
-% rmmod $MOD_LIVEPATCH2
-% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH3/enabled
-livepatch: '$MOD_LIVEPATCH3': initializing unpatching transition
-livepatch: '$MOD_LIVEPATCH3': starting unpatching transition
-livepatch: '$MOD_LIVEPATCH3': completing unpatching transition
-livepatch: '$MOD_LIVEPATCH3': unpatching complete
-% rmmod $MOD_LIVEPATCH3
-% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
-livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
-livepatch: '$MOD_LIVEPATCH': starting unpatching transition
-livepatch: '$MOD_LIVEPATCH': completing unpatching transition
-livepatch: '$MOD_LIVEPATCH': unpatching complete
-% rmmod $MOD_LIVEPATCH"
-
exit 0
--
2.54.0
^ permalink raw reply related
* Re: [PATCH v5 3/8] arm64: entry: add unwind info for various kernel entries
From: Mark Rutland @ 2026-04-29 15:26 UTC (permalink / raw)
To: Dylan Hatch
Cc: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-4-dylanbhatch@google.com>
Hi Dylan,
On Tue, Apr 28, 2026 at 06:36:38PM +0000, Dylan Hatch wrote:
> From: Weinan Liu <wnliu@google.com>
>
> DWARF CFI (Call Frame Information) specifies how to recover the return
> address and callee-saved registers at each PC in a given function.
> Compilers are able to generate the CFI annotations when they compile
> the code to assembly language. For handcrafted assembly, we need to
> annotate them by hand.
>
> Annotate minimal CFI to enable stacktracing using SFrame for kernel
> exception entries through el1*_64_*() paths
I thought we were only consuming SFrame when unwinding an exeption
boundary?
We shouldn't be taking exceptions _from_ the entry assembly functions
unless something has gone horribly wrong, and so I don't see why we'd
need CFI entries for the entry assembly functions.
Am I missing some reason we need CFI entries for the entry assembly
functions? I strongly suspect it is not necessary to add these, and I'd
prefer to omit them.
> and irq entries through call_on_irq_stack()
Needing some sort of unwind annotations for call_on_irq_stack() makes
sense to me, but don't we need something for other assembly functions
too?
We can interrupt things like memset(); I assume we'll treat those as
unreliable until annotated?
Mark.
> Signed-off-by: Weinan Liu <wnliu@google.com>
> Suggested-by: Jens Remus <jremus@linux.ibm.com>
> Reviewed-by: Jens Remus <jremus@linux.ibm.com>
> Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
> ---
> arch/arm64/kernel/entry.S | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index f8018b5c1f9a..dc55b0b19cfa 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -30,6 +30,12 @@
> #include <asm/asm-uaccess.h>
> #include <asm/unistd.h>
>
> +/*
> + * Do not generate .eh_frame. Only generate .debug_frame and optionally
> + * .sframe (via assembler option --gsframe[-N]).
> + */
> + .cfi_sections .debug_frame
> +
> .macro clear_gp_regs
> .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
> mov x\n, xzr
> @@ -575,7 +581,16 @@ SYM_CODE_START_LOCAL(el\el\ht\()_\regsize\()_\label)
> .if \el == 0
> b ret_to_user
> .else
> + /*
> + * Minimal DWARF CFI for unwinding across the call above.
> + * Enable unwinding for el1*_64_*() path only.
> + */
> + .cfi_startproc
> + .cfi_def_cfa_offset PT_REGS_SIZE
> + .cfi_offset 29, S_FP - PT_REGS_SIZE
> + .cfi_offset 30, S_LR - PT_REGS_SIZE
> b ret_to_kernel
> + .cfi_endproc
> .endif
> SYM_CODE_END(el\el\ht\()_\regsize\()_\label)
> .endm
> @@ -872,6 +887,7 @@ NOKPROBE(ret_from_fork)
> * Calls func(regs) using this CPU's irq stack and shadow irq stack.
> */
> SYM_FUNC_START(call_on_irq_stack)
> + .cfi_startproc
> save_and_disable_daif x9
> #ifdef CONFIG_SHADOW_CALL_STACK
> get_current_task x16
> @@ -882,6 +898,9 @@ SYM_FUNC_START(call_on_irq_stack)
> /* Create a frame record to save our LR and SP (implicit in FP) */
> stp x29, x30, [sp, #-16]!
> mov x29, sp
> + .cfi_def_cfa 29, 16
> + .cfi_offset 29, -16
> + .cfi_offset 30, -8
>
> ldr_this_cpu x16, irq_stack_ptr, x17
>
> @@ -897,9 +916,13 @@ SYM_FUNC_START(call_on_irq_stack)
> */
> mov sp, x29
> ldp x29, x30, [sp], #16
> + .cfi_restore 29
> + .cfi_restore 30
> + .cfi_def_cfa 31, 0
> scs_load_current
> restore_irq x9
> ret
> + .cfi_endproc
> SYM_FUNC_END(call_on_irq_stack)
> NOKPROBE(call_on_irq_stack)
>
> --
> 2.54.0.545.g6539524ca2-goog
>
^ permalink raw reply
* Re: [PATCH v5 0/8] unwind, arm64: add sframe unwinder for kernel
From: Mark Rutland @ 2026-04-29 17:18 UTC (permalink / raw)
To: Dylan Hatch
Cc: Roman Gushchin, Weinan Liu, Will Deacon, Josh Poimboeuf,
Indu Bhagat, Peter Zijlstra, Steven Rostedt, Catalin Marinas,
Jiri Kosina, Jens Remus, Prasanna Kumar T S M, Puranjay Mohan,
Song Liu, joe.lawrence, linux-toolchains, linux-kernel,
live-patching, linux-arm-kernel, Randy Dunlap
In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com>
Hi Dylan,
On Tue, Apr 28, 2026 at 06:36:35PM +0000, Dylan Hatch wrote:
> Implement a generic kernel sframe-based [1] unwinder. The main goal is
> to improve reliable stacktrace on arm64 by unwinding across exception
> boundaries.
Thanks for this!
Just as a holding reply: I'm going over the series now, and I have some
partially-written comments that I'll try to finish up and get out
tomorrow.
Mark.
> On x86, the ORC unwinder provides reliable stacktrace through similar
> methodology, but arm64 lacks the necessary support from objtool to
> create ORC unwind tables.
>
> Currently, there's already a sframe unwinder proposed for userspace: [2].
> To maintain common definitions and algorithms for sframe lookup, a
> substantial portion of this patch series aims to refactor the sframe
> lookup code to support both kernel and userspace sframe sections.
>
> Currently, only GNU Binutils support sframe. This series relies on the
> Sframe V3 format, which is supported in binutils 2.46.
>
> These patches are based on Steven Rostedt's sframe/core branch [3],
> which is and aggregation of existing work done for x86 sframe userspace
> unwind, and contains [2]. This branch is, in turn, based on Linux
> v7.0-rc3. This full series (applied to the sframe/core branch) is
> available on github: [4].
>
> Ref:
> [1]: https://sourceware.org/binutils/docs/sframe-spec.html
> [2]: https://lore.kernel.org/lkml/20260127150554.2760964-1-jremus@linux.ibm.com/
> [3]: https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git/log/?h=sframe/core
> [4]: https://github.com/dylanbhatch/linux/tree/sframe-v5
>
> Changes since v4:
> - (Jens) Fix some minor nits.
> - Handle .init.text and .exit.text in function address validation.
>
> Changes since v3:
>
> - (Jens) Clean up patch summaries.
> - (Jens) Rename SFRAME_LOOKUP -> UNWIND_SFRAME_LOOKUP to fit existing
> naming convention.
> - (Randy) Correct typo errors in new config options.
> - (Jens) Move unwind types to a new unwind_types.h to match their
> usage.
> - (Jens) Update KERNEL_[COPY|GET] to use label-based error handling
> like their userspace counterparts.
> - (Jens) Rename SFRAME_UNWINDER -> HAVE_UNWIND_KERNEL_SFRAME and
> ARCH_SUPPORTS_SFRAME_UNWINDER -> ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
> to match existing naming convention.
> - (Jens) Move HAVE_UNWIND_KERNEL_SFRAME config option to arch/Kconfig.
> - (Jens) Rename/move extern definitions of __[start|end]_sframe into
> include/asm-generic/sections.h.
> - (Jens) Fix up CFI annotations at kernel entry.
> - (Jens) Fix error path for unsorted FDE lookup.
> - (Jens) Zero-out module sframe_section before init.
> - (Jens) For SFRAME_VALIDATION, use an arch-specific function-address
> validation helper so that .rodata.text can be correctly handled on
> arm64 vmlinux.
> - (Jens) Fixup and better comment kernel stacktrace code.
>
> Changes since v2:
>
> The biggest change from v2 is the switch from adding a dedicated,
> in-kernel sframe-lookup library, to refactoring/using the existing
> library developed by Josh, Jens, and Steve. Consequently, this series
> now depends on Sframe V3, though this upgrade would likely have been
> necessary anyway. Below is a full accounting of the changes since v2.
>
> - (Josh) Add stricter reliability checks during unwind.
> - (Puranjay, Indu, Jens) Update to use a common sframe library with
> userpace unwind, thus resolving the need to support
> SFRAME_F_FDE_FUNC_START_PCREL, added in binutils 2.45.
> - (Jens) Add check for sframe V3, thus resolving the prior need for V2
> and SFRAME_F_FDE_FUNC_START_PCREL support.
> - (Will) Add ARCH_SUPPORTS_SFRAME_UNWINDER, remove SFRAME_UNWIND_TABLE
> - (Indu) add support for unsorted FDE tables, allowing for module
> sframe lookups.
> - (Mark) Prefer frame-pointer unwind when possible, for better
> performance.
> - Simplify compile-time logic, adding stubbs when necessary.
> - Add support for in-kernel SFRAME_VALIDATION.
> - Rebase onto core/sframe (with v7.0-rc3 base)
>
> Dylan Hatch (7):
> sframe: Allow kernelspace sframe sections
> arm64, unwind: build kernel with sframe V3 info
> sframe: Provide PC lookup for vmlinux .sframe section
> sframe: Allow unsorted FDEs
> arm64/module, sframe: Add sframe support for modules
> sframe: Introduce in-kernel SFRAME_VALIDATION
> unwind: arm64: Use sframe to unwind interrupt frames
>
> Weinan Liu (1):
> arm64: entry: add unwind info for various kernel entries
>
> MAINTAINERS | 3 +-
> Makefile | 8 +
> arch/Kconfig | 27 +-
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/module.h | 6 +
> arch/arm64/include/asm/sections.h | 1 +
> arch/arm64/include/asm/stacktrace/common.h | 6 +
> arch/arm64/include/asm/unwind_sframe.h | 55 +++
> arch/arm64/kernel/entry.S | 23 +
> arch/arm64/kernel/module.c | 8 +
> arch/arm64/kernel/setup.c | 2 +
> arch/arm64/kernel/stacktrace.c | 246 ++++++++++-
> arch/arm64/kernel/vdso/Makefile | 2 +-
> arch/arm64/kernel/vmlinux.lds.S | 2 +
> .../{unwind_user_sframe.h => unwind_sframe.h} | 6 +-
> arch/x86/include/asm/unwind_user.h | 12 +-
> include/asm-generic/sections.h | 4 +
> include/asm-generic/vmlinux.lds.h | 15 +
> include/linux/sframe.h | 67 ++-
> include/linux/unwind_types.h | 46 ++
> include/linux/unwind_user_types.h | 41 --
> kernel/unwind/Makefile | 2 +-
> kernel/unwind/sframe.c | 410 ++++++++++++++----
> kernel/unwind/user.c | 41 +-
> 24 files changed, 827 insertions(+), 207 deletions(-)
> create mode 100644 arch/arm64/include/asm/unwind_sframe.h
> rename arch/x86/include/asm/{unwind_user_sframe.h => unwind_sframe.h} (50%)
> create mode 100644 include/linux/unwind_types.h
>
> --
> 2.54.0.545.g6539524ca2-goog
>
^ permalink raw reply
* Re: [PATCH 20/48] klp-build: Don't use errexit
From: Miroslav Benes @ 2026-04-30 6:50 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, live-patching, Peter Zijlstra, Joe Lawrence,
Song Liu, Miroslav Benes, Petr Mladek
In-Reply-To: <f86bf0b781101152b35437bfe0e6a286f3955247.1776916871.git.jpoimboe@kernel.org>
On Wed, 22 Apr 2026 21:03:48 -0700, Josh Poimboeuf <jpoimboe@kernel.org> wrote:
> The errtrace option (combined with the ERR trap) already serves the same
> function (and more) as errexit, so errexit is redundant. And it has
> more pitfalls. Remove it.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
--
Miroslav
^ permalink raw reply
* Re: [PATCH 21/48] klp-build: Validate patch file existence
From: Miroslav Benes @ 2026-04-30 6:50 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, live-patching, Peter Zijlstra, Joe Lawrence,
Song Liu, Miroslav Benes, Petr Mladek
In-Reply-To: <66e3edb75bf1924c650bce43835acc2053d1cf1a.1776916871.git.jpoimboe@kernel.org>
On Wed, 22 Apr 2026 21:03:49 -0700, Josh Poimboeuf <jpoimboe@kernel.org> wrote:
> Make sure all patch files actually exist. Otherwise there can be
> confusing errors later.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
--
Miroslav
^ permalink raw reply
* Re: [PATCH 22/48] klp-build: Suppress excessive fuzz output by default
From: Miroslav Benes @ 2026-04-30 7:00 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: x86, linux-kernel, live-patching, Peter Zijlstra, Joe Lawrence,
Song Liu, Petr Mladek
In-Reply-To: <58c5ac9ae38760beb06e5ddddb742ea54f922371.1776916871.git.jpoimboe@kernel.org>
On Wed, 22 Apr 2026, Josh Poimboeuf wrote:
> When a patch applies with fuzz, the detailed output from the patch tool
> can be very noisy, especially for big patches.
>
> Suppress the fuzz details by default, while keeping the "applied with
> fuzz" warning. The noise can be restored with '--verbose'.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
---
Miroslav
^ permalink raw reply
* Re: [PATCH v5 5/8] sframe: Allow unsorted FDEs
From: Jens Remus @ 2026-04-30 10:04 UTC (permalink / raw)
To: Dylan Hatch, Roman Gushchin, Weinan Liu, Will Deacon,
Josh Poimboeuf, Indu Bhagat, Peter Zijlstra, Steven Rostedt,
Catalin Marinas, Jiri Kosina
Cc: Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan, Song Liu,
joe.lawrence, linux-toolchains, linux-kernel, live-patching,
linux-arm-kernel, Randy Dunlap, Heiko Carstens
In-Reply-To: <20260428183643.3796063-6-dylanbhatch@google.com>
On 4/28/2026 8:36 PM, Dylan Hatch wrote:
> The .sframe in kernel modules is built without SFRAME_F_FDE_SORTED set.
> In order to allow sframe PC lookup in modules, add a code path to handle
> unsorted FDE tables by doing a simple linear search.
>
> Reviewed-by: Jens Remus <jremus@linux.ibm.com>
> Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
Indu suggested that it would be preferable if a module's .sframe FDE
index table could be sorted during loading of the module to enable
binary search instead of having to resort to linear search. I propose
to drop everything from this patch except for the following, squash
it into the following patch that adds sframe support for modules, and
extend that to sort the .sframe FDE index table. See my separate
feedback to that patch.
> diff --git a/include/linux/sframe.h b/include/linux/sframe.h
> @@ -28,6 +28,7 @@ struct sframe_section {
> unsigned long fres_start;
> unsigned long fres_end;
> unsigned int num_fdes;
> + bool fdes_sorted;
>
> signed char ra_off;
> signed char fp_off;
> diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
> @@ -736,7 +771,6 @@ static int sframe_read_header(struct sframe_section *sec)
>
> if (shdr.preamble.magic != SFRAME_MAGIC ||
> shdr.preamble.version != SFRAME_VERSION_3 ||
> - !(shdr.preamble.flags & SFRAME_F_FDE_SORTED) ||
> !(shdr.preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) ||
> shdr.auxhdr_len) {
> dbg_sec("bad/unsupported sframe header\n");
> @@ -766,6 +800,7 @@ static int sframe_read_header(struct sframe_section *sec)
> return -EINVAL;
> }
>
> + sec->fdes_sorted = shdr.preamble.flags & SFRAME_F_FDE_SORTED;
> sec->num_fdes = num_fdes;
> sec->fdes_start = fdes_start;
> sec->fres_start = fres_start;
Regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
jremus@de.ibm.com / jremus@linux.ibm.com
IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Ehningen; Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM Data Privacy Statement: https://www.ibm.com/privacy/
^ permalink raw reply
* Re: [PATCH v5 7/8] sframe: Introduce in-kernel SFRAME_VALIDATION
From: Jens Remus @ 2026-04-30 10:04 UTC (permalink / raw)
To: Dylan Hatch, Roman Gushchin, Weinan Liu, Will Deacon,
Josh Poimboeuf, Indu Bhagat, Peter Zijlstra, Steven Rostedt,
Catalin Marinas, Jiri Kosina
Cc: Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan, Song Liu,
joe.lawrence, linux-toolchains, linux-kernel, live-patching,
linux-arm-kernel, Randy Dunlap, Heiko Carstens
In-Reply-To: <20260428183643.3796063-8-dylanbhatch@google.com>
On 4/28/2026 8:36 PM, Dylan Hatch wrote:
> Generalize the __safe* helpers to support a non-user-access code path.
>
> This requires arch-specific function address validation. This is because
> arm64 vmlinux keeps .exit.text (normally discarded), and .rodata.text
> sections both of which lie outside the bounds of the normal .text.
> .rodata.text contains code that is never executed by the kernel mapping,
> but for which the toolchain nonetheless generates sframe data, and needs
> to be considered valid for a PC lookup.
>
> Additionally .init.text lies outside .text for all arches and must be
> accounted for as well.
> diff --git a/arch/arm64/include/asm/unwind_sframe.h b/arch/arm64/include/asm/unwind_sframe.h
> @@ -2,7 +2,54 @@
> #ifndef _ASM_ARM64_UNWIND_SFRAME_H
> #define _ASM_ARM64_UNWIND_SFRAME_H
>
> +#include <linux/module.h>
> +#include <linux/sframe.h>
> +#include <asm/sections.h>
> +
> #define SFRAME_REG_SP 31
> #define SFRAME_REG_FP 29
>
> +static inline bool sframe_func_start_addr_valid(struct sframe_section *sec,
> + unsigned long func_addr)
> +{
> + /* Common case for unwinding */
> + if (sec->text_start <= func_addr && func_addr < sec->text_end)
> + return true;
> +
> + if (sec->sec_type != SFRAME_KERNEL)
> + return false;
> +
> + /*
> + * Account for vmlinux and module code outside the normal .text section.
> + * The toolchain still generates sframe data for these functions, so
> + * sframe lookups on them should be allowed.
> + */
> + if (sec == &kernel_sfsec) {
> + if (is_kernel_inittext(func_addr))
> + return true;
> +
> + /* .exit.text is retained in vmlinux on arm64. */
> + if (func_addr >= (unsigned long)__exittext_begin &&
> + func_addr < (unsigned long)__exittext_end)
> + return true;
> +
> +
Nit: Superfluous empty line (2 instead of 1).
> + /*
> + * .rodata.text is never executed from the kernel mapping, but
> + * still has sframe data
> + */
> + if (func_addr >= (unsigned long)_srodatatext &&
> + func_addr < (unsigned long)_erodatatext)
> + return true;
> + } else {
> + struct module *mod = container_of(sec, struct module,
> + arch.sframe_sec);
This currently does not work properly when sframe_validate_section() is
called from sframe_module_init(), which operates on a temporary struct
sframe_section section, that is not (yet) the one in struct module. See
my feedback to the respective patch for how to resolve.
> + if (within_module_mem_type(func_addr, mod, MOD_INIT_TEXT))
> + return true;
> + }
> +
> + return false;
> +}
> +#define sframe_func_start_addr_valid sframe_func_start_addr_valid
> +
> #endif /* _ASM_ARM64_UNWIND_SFRAME_H */
Regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
jremus@de.ibm.com / jremus@linux.ibm.com
IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Ehningen; Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM Data Privacy Statement: https://www.ibm.com/privacy/
^ permalink raw reply
* Re: [PATCH v5 6/8] arm64/module, sframe: Add sframe support for modules
From: Jens Remus @ 2026-04-30 10:04 UTC (permalink / raw)
To: Dylan Hatch, Roman Gushchin, Weinan Liu, Will Deacon,
Josh Poimboeuf, Indu Bhagat, Peter Zijlstra, Steven Rostedt,
Catalin Marinas, Jiri Kosina
Cc: Mark Rutland, Prasanna Kumar T S M, Puranjay Mohan, Song Liu,
joe.lawrence, linux-toolchains, linux-kernel, live-patching,
linux-arm-kernel, Randy Dunlap, Heiko Carstens
In-Reply-To: <20260428183643.3796063-7-dylanbhatch@google.com>
On 4/28/2026 8:36 PM, Dylan Hatch wrote:
> Add sframe table to mod_arch_specific and support sframe PC lookups when
> an .sframe section can be found on incoming modules.
One small fix and a proposal to sort the module's SFrame FDE index.
> diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
A subsequent patch adds a call to sframe_validate_section(), which would
operate on the temporary struct sframe_section instance and thus fail
to use container_of() to access the struct module instance. To resolve
change as follows:
> +void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
> + void *text, size_t text_size)
> +{
> + struct sframe_section sec;
struct sframe_section *sec = &mod->arch.sframe_sec;
It is fine to initialize the module's struct sframe_section instance as
use of the information is guarded by mod->arch.sframe_init, which is
only set if the instance has been full initialized.
> +
> + memset(&sec, 0, sizeof(sec));
Can be dropped if struct module instance got zero-initialized.
> + sec.sec_type = SFRAME_KERNEL;
> + sec.sframe_start = (unsigned long)sframe;
> + sec.sframe_end = (unsigned long)sframe + sframe_size;
> + sec.text_start = (unsigned long)text;
> + sec.text_end = (unsigned long)text + text_size;
Adjust all lines above to pointer access.
> +
> + if (WARN_ON(sframe_read_header(&sec)))
Ditto.
> + return;
> +
> + mod->arch.sframe_sec = sec;
Drop.
> + mod->arch.sframe_init = true;
> +}
Indu suggested that it would be preferable if a module's .sframe FDE
index table could be sorted during loading of the module to enable
binary search instead of having to resort to linear search. I propose
to change this patch as follows to sort the module .sframe FDE index
table in sframe_module_init(). Note that the patch assumes above
changes have been implemented. The sorting is very similar to sorting
of ORC tables in arch/x86/kernel/unwind_orc.c in unwind_module_init().
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -12,6 +12,7 @@
#include <linux/mm.h>
#include <linux/string_helpers.h>
#include <linux/sframe.h>
+#include <linux/sort.h>
#include <linux/unwind_types.h>
#include <asm/unwind_sframe.h>
#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
@@ -1038,6 +1039,50 @@ void __init init_sframe_table(void)
sframe_init = true;
}
+static int sframe_sort_cmp_fde(const void *a, const void *b)
+{
+ const struct sframe_fde_v3 *fde_a = a, *fde_b = b;
+ unsigned long func_start_a, func_start_b;
+
+ func_start_a = (unsigned long)fde_a + fde_a->func_start_off;
+ func_start_b = (unsigned long)fde_b + fde_b->func_start_off;
+
+ return cmp_int(func_start_a, func_start_b);
+}
+
+static void sframe_sort_swap_fde(void *a, void *b, int size)
+{
+ struct sframe_fde_v3 *fde_a = a, *fde_b = b;
+ struct sframe_fde_v3 temp;
+ long delta;
+
+ /* Swap potentially unaligned FDE */
+ memcpy(&temp, fde_a, sizeof(struct sframe_fde_v3));
+ memcpy(fde_a, fde_b, sizeof(struct sframe_fde_v3));
+ memcpy(fde_b, &temp, sizeof(struct sframe_fde_v3));
+
+ /* Adjust FDE function start offset from FDE */
+ delta = (long)((unsigned long)fde_b - (unsigned long)fde_a);
+ fde_a->func_start_off += delta;
+ fde_b->func_start_off -= delta;
+}
+
+static int sframe_sort_fdes(struct sframe_section *sec)
+{
+ void *fdes = (void *)sec->fdes_start;
+ size_t num_fdes = sec->num_fdes;
+
+ if (sec->sec_type != SFRAME_KERNEL)
+ return -EINVAL;
+ if (sec->fdes_sorted)
+ return 0;
+
+ sort(fdes, num_fdes, sizeof(struct sframe_fde_v3),
+ sframe_sort_cmp_fde, sframe_sort_swap_fde);
+ sec->fdes_sorted = true;
+ return 0;
+}
+
void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
void *text, size_t text_size)
{
@@ -1053,6 +1098,8 @@ void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size,
if (WARN_ON(sframe_read_header(sec)))
return;
+ if (WARN_ON(sframe_sort_fdes(sec)))
+ return;
if (WARN_ON(sframe_validate_section(sec)))
return;
Regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
jremus@de.ibm.com / jremus@linux.ibm.com
IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Ehningen; Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM Data Privacy Statement: https://www.ibm.com/privacy/
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