perf events, x86/stacktrace: Make stack walking optional

The current print_context_stack helper that does the stack
walking job is good for usual stacktraces as it walks through
all the stack and reports even addresses that look unreliable,
which is nice when we don't have frame pointers for example.

But we have users like perf that only require reliable
stacktraces, and those may want a more adapted stack walker, so
lets make this function a callback in stacktrace_ops that users
can tune for their needs.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1261024834-5336-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 4 deletions

diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index 044897be021f..3855096c59b8 100644
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -41,10 +41,11 @@ static void backtrace_address(void *data, unsigned long addr, int reliable)
 }
 
 static struct stacktrace_ops backtrace_ops = {
-        .warning = backtrace_warning,
-        .warning_symbol = backtrace_warning_symbol,
-        .stack = backtrace_stack,
-        .address = backtrace_address,
+        .warning        = backtrace_warning,
+        .warning_symbol = backtrace_warning_symbol,
+        .stack          = backtrace_stack,
+        .address        = backtrace_address,
+        .walk_stack     = print_context_stack,
 };
 
 struct frame_head {