diff mbox series

[07/10] ARM: clang: Do not rely on lr register for stacktrace

Message ID 163430230603.459050.13271391202951929788.stgit@devnote2 (mailing list archive)
State New, archived
Headers show
Series kprobes: Make KUnit and add stacktrace on kretprobe tests | expand

Commit Message

Masami Hiramatsu (Google) Oct. 15, 2021, 12:51 p.m. UTC 
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 mbox series

Patch

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)