[PATCH] x86/dumpstack: Walk frames when built with frame pointers

[Richard Yao]

Stack traces are generated by scanning the stack and interpeting
anything that looks like it could be a pointer to something. We do not
need to do this when we have frame pointers, but we do it anyway, with
the distinction that we use the return pointers to mark actual frames by
the absence of a question mark.

The additional verbosity of stack scanning tends to bombard us with
walls of text for no gain in practice, so lets switch to printing only
stack frames when frame pointers are available. That we can spend less
time reading stack traces and more time looking at code.

Signed-off-by: Richard Yao <ryao@xxxxxxxxxx>
---
 arch/x86/kernel/dumpstack.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index d9c12d3..94ffe06 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -162,7 +162,11 @@ static void print_trace_address(void *data, unsigned long addr, int reliable)
 static const struct stacktrace_ops print_trace_ops = {
 	.stack			= print_trace_stack,
 	.address		= print_trace_address,
+#ifdef CONFIG_FRAME_POINTER
+	.walk_stack		= print_context_stack_bp,
+#else
 	.walk_stack		= print_context_stack,
+#endif
 };
 
 void
-- 
1.8.3.2

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