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 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 <liwei...@huawei.com> > --- > tools/lib/perf/include/internal/evlist.h | 1 + > tools/perf/builtin-stat.c | 3 +++ > tools/perf/util/evlist.c | 23 ++++++++++++++++++++++- > 3 files changed, 26 insertions(+), 1 deletion(-) > > diff --git a/tools/lib/perf/include/internal/evlist.h > b/tools/lib/perf/include/internal/evlist.h > index 2d0fa02b036f..c02d7e583846 100644 > --- a/tools/lib/perf/include/internal/evlist.h > +++ b/tools/lib/perf/include/internal/evlist.h > @@ -17,6 +17,7 @@ struct perf_evlist { > struct list_head entries; > int nr_entries; > bool has_user_cpus; > + bool open_per_thread; > struct perf_cpu_map *cpus; > struct perf_cpu_map *all_cpus; > struct perf_thread_map *threads; > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c > index fddc97cac984..6e6ceacce634 100644 > --- a/tools/perf/builtin-stat.c > +++ b/tools/perf/builtin-stat.c > @@ -725,6 +725,9 @@ static int __run_perf_stat(int argc, const char **argv, > int run_idx) > if (group) > perf_evlist__set_leader(evsel_list); > > + if (!(target__has_cpu(&target) && !target__has_per_thread(&target))) > + evsel_list->core.open_per_thread = true; > + > if (affinity__setup(&affinity) < 0) > return -1; > > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c > index e3fa3bf7498a..bf8a3ccc599f 100644 > --- a/tools/perf/util/evlist.c > +++ b/tools/perf/util/evlist.c > @@ -383,6 +383,15 @@ void evlist__disable(struct evlist *evlist) > int cpu, i, imm = 0; > bool has_imm = false; > > + if (evlist->core.open_per_thread) { > + evlist__for_each_entry(evlist, pos) { > + if (pos->disabled || !evsel__is_group_leader(pos) || > !pos->core.fd) > + continue; > + evsel__disable(pos); > + } > + goto out; > + } > + > if (affinity__setup(&affinity) < 0) > return; > > @@ -414,6 +423,7 @@ void evlist__disable(struct evlist *evlist) > pos->disabled = true; > } > > +out: > evlist->enabled = false; > } > > @@ -423,6 +433,15 @@ void evlist__enable(struct evlist *evlist) > struct affinity affinity; > int cpu, i; > > + if (evlist->core.open_per_thread) { > + evlist__for_each_entry(evlist, pos) { > + if (!evsel__is_group_leader(pos) || !pos->core.fd) > + continue; > + evsel__enable(pos); > + } > + goto out; > + } > + > if (affinity__setup(&affinity) < 0) > return; > > @@ -444,6 +463,7 @@ void evlist__enable(struct evlist *evlist) > pos->disabled = false; > } > > +out: > evlist->enabled = true; > } > > @@ -1223,9 +1243,10 @@ void evlist__close(struct evlist *evlist) > > /* > * With perf record core.cpus is usually NULL. > + * Or perf stat may open events per-thread. > * Use the old method to handle this for now. > */ > - if (!evlist->core.cpus) { > + if (evlist->core.open_per_thread || !evlist->core.cpus) { > evlist__for_each_entry_reverse(evlist, evsel) > evsel__close(evsel); > return; > -- > 2.17.1 >