perf events, x86/stacktrace: Fix performance/softlockup by providing a special frame pointer-only stack walker
It's just wasteful for stacktrace users like perf to walk
through every entries on the stack whereas these only accept
reliable ones, ie: that the frame pointer validates.
Since perf requires pure reliable stacktraces, it needs a stack
walker based on frame pointers-only to optimize the stacktrace
processing.
This might solve some near-lockup scenarios that can be triggered
by call-graph tracing timer events.
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: <1261024834-5336-2-git-send-regression-fweisbec@gmail.com>
[ v2: fix for modular builds and small detail tidyup ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 6c75151..35e8912 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -22,6 +22,12 @@
const struct stacktrace_ops *ops, void *data,
unsigned long *end, int *graph);
+extern unsigned long
+print_context_stack_bp(struct thread_info *tinfo,
+ unsigned long *stack, unsigned long bp,
+ const struct stacktrace_ops *ops, void *data,
+ unsigned long *end, int *graph);
+
/* Generic stack tracer with callbacks */
struct stacktrace_ops {