Messages in this thread | | | Date | Mon, 7 Sep 2015 21:08:25 +0800 | From | "Wangnan (F)" <> | Subject | Re: [PATCH] perf report: Fix invalid memory accessing |
| |
On 2015/9/7 21:03, Jiri Olsa wrote: > On Mon, Sep 07, 2015 at 12:51:55PM +0000, Wang Nan wrote: >> Commit e1e499aba570a2ea84d29822b7ea637ac41d9a51 (perf tools: Add >> processor socket info to hist_entry and addr_location) reads env->cpu >> array for each sample using index al.cpu. However, al.cpu can be -1 if >> sample doesn't select PERF_SAMPLE_CPU. Also, env->cpu can be invalid if >> feature CPU_TOPOLOGY not selected. We should validate env->cpu and al.cpu >> before setting al.socket. >> >> Signed-off-by: Wang Nan <wangnan0@huawei.com> >> Cc: Kan Liang <kan.liang@intel.com> >> Cc: Adrian Hunter <adrian.hunter@intel.com> >> Cc: Andi Kleen <ak@linux.intel.com> >> Cc: Jiri Olsa <jolsa@kernel.org> >> Cc: Namhyung Kim <namhyung@kernel.org> >> Cc: Stephane Eranian <eranian@google.com> >> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> >> --- >> >> Although theoretically CPU_TOPOLOGY feature should always be selected by >> 'perf record', I did generate a perf.data without that feature. It has >> header like this: >> >> # perf report -i ./bad.perf.data --header-only >> # ======== >> # captured on: Thu Jan 8 09:30:15 2009 >> # hostname : localhost >> # os release : 3.10.49-gd672fc4 >> # perf version : 4.2.gc9df >> # arch : aarch64 >> # nrcpus online : 8 >> # nrcpus avail : 8 >> # total memory : 1850768 kB >> # cmdline : /system/bin/perf record -e sync:sync_timeline -e kgsl:kgsl_register_event -g -a sleep 5 >> # event : name = sync:sync_timeline, , id = { 1107, 1108, 1109, 1110, 1111, 1112 }, type = 2, size = 112, config = 0x3e7, { sample_period, sample_freq } = 1, sample_type = IP|TID|TIME|CALLCHAIN|ID|CPU|PERIOD|RAW, read_format = ID, disabled = 1, inherit = 1, mmap = 1, comm = 1, task = 1, sample_id_all = 1, exclude_guest = 1, mmap2 = 1, comm_exec = 1 >> # event : name = kgsl:kgsl_register_event, , id = { 1113, 1114, 1115, 1116, 1117, 1118 }, type = 2, size = 112, config = 0x350, { sample_period, sample_freq } = 1, sample_type = IP|TID|TIME|CALLCHAIN|ID|CPU|PERIOD|RAW, read_format = ID, disabled = 1, inherit = 1, sample_id_all = 1, exclude_guest = 1 >> # pmu mappings: cpu = 4, software = 1, tracepoint = 2 >> # ======== >> # >> >> It should be: >> >> # ======== >> # captured on: Thu Jan 8 11:26:41 2009 >> ... >> # HEADER_CPU_TOPOLOGY info available, use -I to display >> # pmu mappings: cpu = 4, software = 1, tracepoint = 2 >> # ======== >> >> However, bad perf.data appears randomly. I can't stably reproduce it, so I >> guess there might have another invalid memory accessing. >> >> --- >> tools/perf/builtin-report.c | 12 ++++++++++-- >> 1 file changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c >> index 4b43245..16d097d 100644 >> --- a/tools/perf/builtin-report.c >> +++ b/tools/perf/builtin-report.c >> @@ -158,8 +158,16 @@ static int process_sample_event(struct perf_tool *tool, >> return -1; >> } >> >> - /* read socket id from perf.data for perf report */ >> - al.socket = env->cpu[al.cpu].socket_id; >> + /* >> + * read socket id from perf.data for perf report >> + * al.cpu is invalid if PERF_SAMPLE_CPU is not selected by this >> + * sample. >> + * env->cpu is invalid if CPU_TOPOLOGY feature is not set in >> + * header. >> + */ >> + al.socket = -1; >> + if (env->cpu && al.cpu >= 0) >> + al.socket = env->cpu[al.cpu].socket_id; > perf_event__preprocess_sample initializes al.socket from current system
No. For 'perf report' it initializes al.cpu from sample.
Commit message of e1e499aba570a2ea84d29822b7ea637ac41d9a51:
Finor 'perf report', the socket id info is from perf.data.
For others, the socket id info is from current system.
And at least checking of env->cpu is essential. I'm looking the problem I reported. Looks like build_cpu_topology() is possible to fail.
Thank you. > do we want to move this over there? > > also this change is just report specific, and we could need > this in at least perf top > > jirka
| |