[PATCH linux-next] ARM: unwind: use ex_frame with CONFIG_UNWINDER_FRAME_POINTER

From: guo ziliang <redacted>

We define ex_frame with CONFIG_UNWINDER_FRAME_POINTER in struct stackframe,
struct stackframe
{
	......
#ifdef CONFIG_UNWINDER_FRAME_POINTER
    bool ex_frame;
#endif
};
but we just use ex_frame without CONFIG_UNWINDER_FRAME_POINTER in
return_address() and unwind_frame(). 
Maybe we should fix it.

Signed-off-by: guo ziliang <redacted>
---
 arch/arm/kernel/return_address.c | 2 ++
 arch/arm/kernel/stacktrace.c     | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/arch/arm/kernel/return_address.c b/arch/arm/kernel/return_address.c
index ac15db6..dae49e7 100644
--- a/arch/arm/kernel/return_address.c
+++ b/arch/arm/kernel/return_address.c

@@ -47,7 +47,9 @@ void *return_address(unsigned int level)
 	frame.kr_cur = NULL;
 	frame.tsk = current;
 #endif
+#ifdef CONFIG_UNWINDER_FRAME_POINTER
 	frame.ex_frame = false;
+#endif

 	walk_stackframe(&frame, save_return_addr, &data);

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 620aa82..338f552 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c

@@ -82,6 +82,7 @@ int notrace unwind_frame(struct stackframe *frame)
 	if (frame_pointer_check(frame))
 		return -EINVAL;

+#ifdef CONFIG_UNWINDER_FRAME_POINTER
 	/*
 	 * When we unwind through an exception stack, include the saved PC
 	 * value into the stack trace.

@@ -102,6 +103,7 @@ int notrace unwind_frame(struct stackframe *frame)
 		frame->ex_frame = false;
 		return 0;
 	}
+#endif

 	/* restore the registers from the stack frame */
 #ifdef CONFIG_CC_IS_CLANG

@@ -119,8 +121,10 @@ int notrace unwind_frame(struct stackframe *frame)
 					(void *)frame->fp, &frame->kr_cur);
 #endif

+#ifdef CONFIG_UNWINDER_FRAME_POINTER
 	if (in_entry_text(frame->pc))
 		frame->ex_frame = true;
+#endif

 	return 0;
 }

-- 
1.8.3.1

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On Thu, May 18, 2023 at 10:58 AM [off-list ref] wrote:

From: guo ziliang <redacted>

We define ex_frame with CONFIG_UNWINDER_FRAME_POINTER in struct stackframe,
struct stackframe
{
        ......
#ifdef CONFIG_UNWINDER_FRAME_POINTER
    bool ex_frame;
#endif
};
but we just use ex_frame without CONFIG_UNWINDER_FRAME_POINTER in
return_address() and unwind_frame().
Maybe we should fix it.

Signed-off-by: guo ziliang <redacted>

Looks reasonable:
Acked-by: Linus Walleij <redacted>

Is it possible to create a .config which expose this problem?
Then mention in the commit message "if you select A and B
then compilation fails..."

Yours,
Linus Walleij

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