Messages in this thread | | | From | Namhyung Kim <> | Date | Wed, 23 Sep 2020 22:49:52 +0900 | Subject | Re: [PATCH 1/2] perf stat: Fix segfault when counting armv8_pmu events |
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On Wed, Sep 23, 2020 at 2:44 PM Jiri Olsa <jolsa@redhat.com> wrote: > > On Tue, Sep 22, 2020 at 11:13:45AM +0800, Wei Li wrote: > > When executing perf stat with armv8_pmu events with a workload, it will > > report a segfault as result. > > please share the perf stat command line you see that segfault for
It seems the description in the patch 0/2 already has it:
[root@localhost hulk]# tools/perf/perf stat -e armv8_pmuv3_0/ll_cache_rd/,armv8_pmuv3_0/ll_cache_miss_rd/ ls > /dev/null Segmentation fault
Thanks Namhyun
> > thanks, > jirka > > > > > (gdb) bt > > #0 0x0000000000603fc8 in perf_evsel__close_fd_cpu (evsel=<optimized out>, > > cpu=<optimized out>) at evsel.c:122 > > #1 perf_evsel__close_cpu (evsel=evsel@entry=0x716e950, cpu=7) at evsel.c:156 > > #2 0x00000000004d4718 in evlist__close (evlist=0x70a7cb0) at util/evlist.c:1242 > > #3 0x0000000000453404 in __run_perf_stat (argc=3, argc@entry=1, argv=0x30, > > argv@entry=0xfffffaea2f90, run_idx=119, run_idx@entry=1701998435) > > at builtin-stat.c:929 > > #4 0x0000000000455058 in run_perf_stat (run_idx=1701998435, argv=0xfffffaea2f90, > > argc=1) at builtin-stat.c:947 > > #5 cmd_stat (argc=1, argv=0xfffffaea2f90) at builtin-stat.c:2357 > > #6 0x00000000004bb888 in run_builtin (p=p@entry=0x9764b8 <commands+288>, > > argc=argc@entry=4, argv=argv@entry=0xfffffaea2f90) at perf.c:312 > > #7 0x00000000004bbb54 in handle_internal_command (argc=argc@entry=4, > > argv=argv@entry=0xfffffaea2f90) at perf.c:364 > > #8 0x0000000000435378 in run_argv (argcp=<synthetic pointer>, > > argv=<synthetic pointer>) at perf.c:408 > > #9 main (argc=4, argv=0xfffffaea2f90) at perf.c:538 > > > > After debugging, i found the root reason is that the xyarray fd is created > > by evsel__open_per_thread() ignoring the cpu passed in > > create_perf_stat_counter(), while the evsel' cpumap is assigned as the > > corresponding PMU's cpumap in __add_event(). Thus, the xyarray fd is created > > with ncpus of dummy cpumap and an out of bounds 'cpu' index will be used in > > perf_evsel__close_fd_cpu(). > > > > To address this, add a flag to mark this situation and avoid using the > > affinity technique when closing/enabling/disabling events. > > > > Fixes: 7736627b865d ("perf stat: Use affinity for closing file descriptors") > > Fixes: 704e2f5b700d ("perf stat: Use affinity for enabling/disabling events") > > Signed-off-by: Wei Li <liwei391@huawei.com> > > ---
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