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Commit 114067b6 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
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perf tools: Check if callchain is corrupted 



We faced segmentation fault on perf top -G at very high sampling rate
due to a corrupted callchain. While the root cause was not revealed (I
failed to figure it out), this patch tries to protect us from the
segfault on such cases.

Reported-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarNamhyung Kim <namhyung.kim@lge.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sunjin Yang <fan4326@gmail.com>
Link: http://lkml.kernel.org/r/1338443007-24857-2-git-send-email-namhyung.kim@lge.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 47260645

include/linux/perf_event.h

+2 −2
Original line number Diff line number Diff line
@@ -555,6 +555,8 @@ enum perf_event_type { 
	PERF_RECORD_MAX,			/* non-ABI */

};



#define PERF_MAX_STACK_DEPTH		255



enum perf_callchain_context {

	PERF_CONTEXT_HV			= (__u64)-32,

	PERF_CONTEXT_KERNEL		= (__u64)-128,
@@ -609,8 +611,6 @@ struct perf_guest_info_callbacks { 
#include <linux/sysfs.h>

#include <asm/local.h>



#define PERF_MAX_STACK_DEPTH		255



struct perf_callchain_entry {

	__u64				nr;

	__u64				ip[PERF_MAX_STACK_DEPTH];

tools/perf/util/session.c

+13 −1
Original line number Diff line number Diff line
@@ -300,6 +300,11 @@ int machine__resolve_callchain(struct machine *self, 


	callchain_cursor_reset(&callchain_cursor);



	if (chain->nr > PERF_MAX_STACK_DEPTH) {

		pr_warning("corrupted callchain. skipping...\n");

		return 0;

	}



	for (i = 0; i < chain->nr; i++) {

		u64 ip;

		struct addr_location al;
@@ -318,7 +323,14 @@ int machine__resolve_callchain(struct machine *self, 
			case PERF_CONTEXT_USER:

				cpumode = PERF_RECORD_MISC_USER;	break;

			default:

				break;

				pr_debug("invalid callchain context: "

					 "%"PRId64"\n", (s64) ip);

				/*

				 * It seems the callchain is corrupted.

				 * Discard all.

				 */

				callchain_cursor_reset(&callchain_cursor);

				return 0;

			}

			continue;

		}