Messages in this thread Patch in this message | | | From | Masami Hiramatsu <> | Subject | [PATCH v3 7/9] ARM: clang: Do not rely on lr register for stacktrace | Date | Thu, 21 Oct 2021 09:55:17 +0900 |
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Currently the stacktrace on clang compiled arm kernel uses the 'lr' register to find the first frame address from pt_regs. However, that is wrong after calling another function, because the 'lr' register is used by 'bl' instruction and never be recovered.
As same as gcc arm kernel, directly use the frame pointer (r11) of the pt_regs to find the first frame address.
Note that this fixes kretprobe stacktrace issue only with CONFIG_UNWINDER_FRAME_POINTER=y. For the CONFIG_UNWINDER_ARM, we need another fix.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> --- Changes in v2: - Fix typos in changelog. --- arch/arm/kernel/stacktrace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c index 76ea4178a55c..db798eac7431 100644 --- a/arch/arm/kernel/stacktrace.c +++ b/arch/arm/kernel/stacktrace.c @@ -54,8 +54,7 @@ int notrace unwind_frame(struct stackframe *frame) frame->sp = frame->fp; frame->fp = *(unsigned long *)(fp); - frame->pc = frame->lr; - frame->lr = *(unsigned long *)(fp + 4); + frame->pc = *(unsigned long *)(fp + 4); #else /* check current frame pointer is within bounds */ if (fp < low + 12 || fp > high - 4)
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