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| author | Wang Nan <wangnan0@huawei.com> | 2015-04-25 07:25:03 +0000 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2015-04-27 13:24:32 -0300 |
| commit | c671835021798c1c40ca0b55b49feff76ed5e0e1 (patch) | |
| tree | 6479c2cb7432d9105ef05f76f18c99549cdbcebd /tools | |
| parent | 410ceb8f2f1d4edeb02d229ef192e76602005b8b (diff) | |
| download | linux-c671835021798c1c40ca0b55b49feff76ed5e0e1.tar.gz linux-c671835021798c1c40ca0b55b49feff76ed5e0e1.tar.bz2 linux-c671835021798c1c40ca0b55b49feff76ed5e0e1.zip | |
perf top: Fix a segfault when kernel map is restricted.
Perf top raise a warning if a kernel sample is collected but kernel map
is restricted. The warning message needs to dereference al.map->dso...
However, previous perf_event__preprocess_sample() doesn't always
guarantee al.map != NULL, for example, when kernel map is restricted.
This patch validates al.map before dereferencing, avoid the segfault.
Before this patch:
$ cat /proc/sys/kernel/kptr_restrict
1
$ perf top -p 120183
perf: Segmentation fault
-------- backtrace --------
/path/to/perf[0x509868]
/lib64/libc.so.6(+0x3545f)[0x7f9a1540045f]
/path/to/perf[0x448820]
/path/to/perf(cmd_top+0xe3c)[0x44a5dc]
/path/to/perf[0x4766a2]
/path/to/perf(main+0x5f5)[0x42e545]
/lib64/libc.so.6(__libc_start_main+0xf4)[0x7f9a153ecbd4]
/path/to/perf[0x42e674]
And gdb call trace:
Program received signal SIGSEGV, Segmentation fault.
perf_event__process_sample (machine=0xa44030, sample=0x7fffffffa4c0, evsel=0xa43b00, event=0x7ffff41c3000, tool=0x7fffffffa8a0)
at builtin-top.c:736
736 !RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION]) ?
(gdb) bt
#0 perf_event__process_sample (machine=0xa44030, sample=0x7fffffffa4c0, evsel=0xa43b00, event=0x7ffff41c3000, tool=0x7fffffffa8a0)
at builtin-top.c:736
#1 perf_top__mmap_read_idx (top=top@entry=0x7fffffffa8a0, idx=idx@entry=0) at builtin-top.c:855
#2 0x000000000044a5dd in perf_top__mmap_read (top=0x7fffffffa8a0) at builtin-top.c:872
#3 __cmd_top (top=0x7fffffffa8a0) at builtin-top.c:997
#4 cmd_top (argc=<optimized out>, argv=<optimized out>, prefix=<optimized out>) at builtin-top.c:1267
#5 0x00000000004766a3 in run_builtin (p=p@entry=0x8a6ce8 <commands+264>, argc=argc@entry=3, argv=argv@entry=0x7fffffffdf70)
at perf.c:371
#6 0x000000000042e546 in handle_internal_command (argv=0x7fffffffdf70, argc=3) at perf.c:430
#7 run_argv (argv=0x7fffffffdcf0, argcp=0x7fffffffdcfc) at perf.c:474
#8 main (argc=3, argv=0x7fffffffdf70) at perf.c:589
(gdb)
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1429946703-80807-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/builtin-top.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index 1cb3436276d1..6a4d5d41c671 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -733,7 +733,7 @@ static void perf_event__process_sample(struct perf_tool *tool, "Kernel address maps (/proc/{kallsyms,modules}) are restricted.\n\n" "Check /proc/sys/kernel/kptr_restrict.\n\n" "Kernel%s samples will not be resolved.\n", - !RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION]) ? + al.map && !RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION]) ? " modules" : ""); if (use_browser <= 0) sleep(5); |