From: Masami Hiramatsu mhiramat@kernel.org
[ Upstream commit b3ea5d56f212ad81328c82454829a736197ebccc ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 6e8a50de40e2b..c10c1de244eba 100644 --- a/arch/arm/kernel/stacktrace.c +++ b/arch/arm/kernel/stacktrace.c @@ -51,8 +51,7 @@ 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)