[RFC PATCH v2 11/15] unwind_user/sframe: Enable archs with encoded SFrame CFA offsets
From: Jens Remus <hidden>
Date: 2025-12-05 17:15:37
Also in:
linux-s390, linux-trace-kernel, lkml
Subsystem:
generic include/asm header files, the rest, userspace stack unwinding · Maintainers:
Arnd Bergmann, Linus Torvalds, Josh Poimboeuf, Steven Rostedt
Enable architectures, such as s390, which store SFrame CFA offset values
encoded, to e.g. make (better) use of unsigned 8-bit SFrame offsets.
Signed-off-by: Jens Remus <redacted>
---
Notes (jremus):
Changes in RFC v2:
- Rename generic_sframe_cfa_offset_decode() to
sframe_cfa_offset_decode(). (Josh)
include/asm-generic/unwind_user_sframe.h | 8 ++++++++
kernel/unwind/sframe.c | 1 +
2 files changed, 9 insertions(+)
diff --git a/include/asm-generic/unwind_user_sframe.h b/include/asm-generic/unwind_user_sframe.h
index 163961ca5252..80ae9bfaa88d 100644
--- a/include/asm-generic/unwind_user_sframe.h
+++ b/include/asm-generic/unwind_user_sframe.h@@ -10,6 +10,14 @@ #define SFRAME_SP_OFFSET 0 #endif +#ifndef sframe_cfa_offset_decode +static inline s32 sframe_cfa_offset_decode(s32 offset) +{ + return offset; +} +#define sframe_cfa_offset_decode sframe_cfa_offset_decode +#endif + #ifndef sframe_init_reginfo static inline void sframe_init_reginfo(struct unwind_user_reginfo *reginfo, s32 offset)
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 45cd7380ac38..92f770fc21f6 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c@@ -226,6 +226,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, UNSAFE_GET_USER_INC(cfa_off, cur, offset_size, Efault); offset_count--; + cfa_off = sframe_cfa_offset_decode(cfa_off); ra_off = sec->ra_off; if (!ra_off && offset_count) {
--
2.51.0