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ARM: clang: Do not rely on lr register for stacktrace

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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>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2021-10-21 09:55:17 +09:00 • committed by Steven Rostedt (VMware)
parent cd9bc2c925
commit b3ea5d56f2
1 changed files with 1 additions and 2 deletions
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3
arch/arm/kernel/stacktrace.c
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@ -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)