[PATCH v13 17/18] unwind_user/sframe/x86: Enable sframe unwinding on x86
From: Jens Remus <hidden>
Date: 2026-01-27 15:07:06
Also in:
bpf, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit), x86 stack unwinding · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Josh Poimboeuf, Peter Zijlstra
From: Josh Poimboeuf <jpoimboe@kernel.org>
The x86 SFrame V3 implementation works fairly well, starting with
binutils 2.46. Enable it.
[ Jens Remus: Reword commit message for SFrame V3, starting with
binutils 2.46. ]
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <redacted>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Indu Bhagat <redacted>
Cc: "Jose E. Marchesi" <redacted>
Cc: Beau Belgrave <redacted>
Cc: Jens Remus <redacted>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Florian Weimer <redacted>
Cc: Sam James <redacted>
Cc: Kees Cook <kees@kernel.org>
Cc: "Carlos O'Donell" <redacted>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Jens Remus <redacted>
---
Notes (jremus):
Changes in v13:
- Naive implementation of unwind_user_get_reg() to support SFrame V3
flexible FDEs (e.g. used to represent DRAP pattern).
- Define SFRAME_REG_SP and SFRAME_REG_FP to the respective x86-64
DWARF register numbers.
- Reword commit message for SFrame V3 and (upcoming) binutils 2.46.
arch/x86/Kconfig | 1 +
arch/x86/include/asm/unwind_user.h | 34 +++++++++++++++++++++++
arch/x86/include/asm/unwind_user_sframe.h | 12 ++++++++
3 files changed, 47 insertions(+)
create mode 100644 arch/x86/include/asm/unwind_user_sframe.h
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 80527299f859..195cb99a590c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig@@ -301,6 +301,7 @@ config X86 select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL select HAVE_UNSTABLE_SCHED_CLOCK select HAVE_UNWIND_USER_FP if X86_64 + select HAVE_UNWIND_USER_SFRAME if X86_64 select HAVE_USER_RETURN_NOTIFIER select HAVE_GENERIC_VDSO select VDSO_GETRANDOM if X86_64
diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwind_user.h
index f38f7c5ff1de..ae46906c3b39 100644
--- a/arch/x86/include/asm/unwind_user.h
+++ b/arch/x86/include/asm/unwind_user.h@@ -15,6 +15,40 @@ static inline int unwind_user_word_size(struct pt_regs *regs) return user_64bit_mode(regs) ? 8 : 4; } +static inline int unwind_user_get_reg(unsigned long *val, unsigned int regnum) +{ +#ifdef CONFIG_X86_64 + const struct pt_regs *regs = task_pt_regs(current); + + switch (regnum) { + /* DWARF register numbers 0..15 */ + case 0: *val = regs->ax; break; + case 1: *val = regs->dx; break; + case 2: *val = regs->cx; break; + case 3: *val = regs->bx; break; + case 4: *val = regs->si; break; + case 5: *val = regs->di; break; + case 6: *val = regs->bp; break; + case 7: *val = regs->sp; break; + case 8: *val = regs->r8; break; + case 9: *val = regs->r9; break; + case 10: *val = regs->r10; break; + case 11: *val = regs->r11; break; + case 12: *val = regs->r12; break; + case 13: *val = regs->r13; break; + case 14: *val = regs->r14; break; + case 15: *val = regs->r15; break; + default: + return -EINVAL; + } + return 0; +#else /* !CONFIG_X86_64 */ + return -EINVAL; +#endif /* !CONFIG_X86_64 */ + +} +#define unwind_user_get_reg unwind_user_get_reg + #endif /* CONFIG_UNWIND_USER */ #ifdef CONFIG_HAVE_UNWIND_USER_FP
diff --git a/arch/x86/include/asm/unwind_user_sframe.h b/arch/x86/include/asm/unwind_user_sframe.h
new file mode 100644
index 000000000000..d828ae1a4aac
--- /dev/null
+++ b/arch/x86/include/asm/unwind_user_sframe.h@@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_UNWIND_USER_SFRAME_H +#define _ASM_X86_UNWIND_USER_SFRAME_H + +#ifdef CONFIG_X86_64 + +#define SFRAME_REG_SP 7 +#define SFRAME_REG_FP 6 + +#endif + +#endif /* _ASM_X86_UNWIND_USER_SFRAME_H */
--
2.51.0