[tip:perf/core] perf top: Show backtrace when handling a SIGSEGV on --stdio mode

From: tip-bot for Arnaldo Carvalho de Melo
Date: Thu Aug 20 2015 - 06:01:11 EST


Commit-ID: 09f4d78ab0af0973e1a49c10eb7bf977c68cc3aa
Gitweb: http://git.kernel.org/tip/09f4d78ab0af0973e1a49c10eb7bf977c68cc3aa
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Wed, 19 Aug 2015 15:16:08 -0300
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 19 Aug 2015 15:16:08 -0300

perf top: Show backtrace when handling a SIGSEGV on --stdio mode

It was just freezing instead of informing about the SEGV, fix it and
also print a backtrace, just like in the TUI mode and in 'perf trace'.

Tested by provoking a NULL deref when pressing 'z':

0.31% libc-2.20.so [.] malloc_consolidate
0.31% ld-2.20.so [.] _dl_relocate_object
0.28% cc1 [.] ht_lookup
0.28% cc1 [.] ira_init_register_move_cost
perf: Segmentation fault
Obtained 7 stack frames.
perf(dump_stack+0x32) [0x4d69f2]
perf(sighandler_dump_stack+0x29) [0x4d6a89]
/lib64/libc.so.6(+0x34960) [0x7f5064333960]
perf() [0x438790]
/lib64/libpthread.so.0(+0x752a) [0x7f50663dd52a]
/lib64/libc.so.6(clone+0x6d) [0x7f50643ff22d]
#

Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-pewrpzqd29rgmhu2wkk7fhww@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-top.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index ecf3197..6135cc0 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -601,8 +601,8 @@ static void display_sig(int sig __maybe_unused)

static void display_setup_sig(void)
{
- signal(SIGSEGV, display_sig);
- signal(SIGFPE, display_sig);
+ signal(SIGSEGV, sighandler_dump_stack);
+ signal(SIGFPE, sighandler_dump_stack);
signal(SIGINT, display_sig);
signal(SIGQUIT, display_sig);
signal(SIGTERM, display_sig);
--
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