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perf events, x86/stacktrace: Fix performance/softlockup by providing a special frame pointer-only stack walker

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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>
This commit is contained in:
Frederic Weisbecker 2009-12-17 05:40:34 +01:00 committed by Ingo Molnar
parent 61c1917f47
commit 06d65bda75
3 changed files with 33 additions and 3 deletions
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6
arch/x86/include/asm/stacktrace.h
View file

@ -22,6 +22,12 @@ print_context_stack(struct thread_info *tinfo,
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 {

2
arch/x86/kernel/cpu/perf_event.c
View file

@ -2336,7 +2336,7 @@ static const struct stacktrace_ops backtrace_ops = {
.warning_symbol = backtrace_warning_symbol,
.stack = backtrace_stack,
.address = backtrace_address,
.walk_stack = print_context_stack,
.walk_stack = print_context_stack_bp,
};
#include "../dumpstack.h"

24
arch/x86/kernel/dumpstack.c
View file

@ -109,6 +109,30 @@ print_context_stack(struct thread_info *tinfo,
}
return bp;
}
EXPORT_SYMBOL_GPL(print_context_stack);
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)
{
struct stack_frame *frame = (struct stack_frame *)bp;
unsigned long *ret_addr = &frame->return_address;
while (valid_stack_ptr(tinfo, ret_addr, sizeof(*ret_addr), end)) {
unsigned long addr = *ret_addr;
if (__kernel_text_address(addr)) {
ops->address(data, addr, 1);
frame = frame->next_frame;
ret_addr = &frame->return_address;
print_ftrace_graph_addr(addr, data, ops, tinfo, graph);
}
}
return (unsigned long)frame;
}
EXPORT_SYMBOL_GPL(print_context_stack_bp);
static void