linux/tools/perf
Thomas Richter e47749f179 perf jevent: fix core dump on software events on s390
Running commands such as
 # ./perf stat -e cs -- true
 Segmentation fault (core dumped)
 # ./perf stat -e cpu-clock-- true
 Segmentation fault (core dumped)
 #

dump core. This should not happen as these events are defined
even when no hardware PMU is available.
Debugging this reveals this call chain:

  perf_pmus__find_by_type(type=1)
  +--> pmu_read_sysfs(core_only=false)
       +--> perf_pmu__find2(dirfd=3, name=0x152a113 "software")
            +--> perf_pmu__lookup(pmus=0x14f0568 <other_pmus>, dirfd=3,
                                  lookup_name=0x152a113 "software")
                 +--> perf_pmu__find_events_table (pmu=0x1532130)

Now the pmu is "software" and it tries to find a proper table
generated by the pmu-event generation process for s390:

 # cd pmu-events/
 # ./jevents.py  s390 all /root/linux/tools/perf/pmu-events/arch |\
        grep -E '^const struct pmu_table_entry'
 const struct pmu_table_entry pmu_events__cf_z10[] = {
 const struct pmu_table_entry pmu_events__cf_z13[] = {
 const struct pmu_table_entry pmu_metrics__cf_z13[] = {
 const struct pmu_table_entry pmu_events__cf_z14[] = {
 const struct pmu_table_entry pmu_metrics__cf_z14[] = {
 const struct pmu_table_entry pmu_events__cf_z15[] = {
 const struct pmu_table_entry pmu_metrics__cf_z15[] = {
 const struct pmu_table_entry pmu_events__cf_z16[] = {
 const struct pmu_table_entry pmu_metrics__cf_z16[] = {
 const struct pmu_table_entry pmu_events__cf_z196[] = {
 const struct pmu_table_entry pmu_events__cf_zec12[] = {
 const struct pmu_table_entry pmu_metrics__cf_zec12[] = {
 const struct pmu_table_entry pmu_events__test_soc_cpu[] = {
 const struct pmu_table_entry pmu_metrics__test_soc_cpu[] = {
 const struct pmu_table_entry pmu_events__test_soc_sys[] = {
 #

However event "software" is not listed, as can be seen in the
generated const struct pmu_events_map pmu_events_map[].
So in function perf_pmu__find_events_table(), the variable
table is initialized to NULL, but never set to a proper
value. The function scans all generated &pmu_events_map[]
tables, but no table matches, because the tables are
s390 CPU Measurement unit specific:

  i = 0;
  for (;;) {
      const struct pmu_events_map *map = &pmu_events_map[i++];
      if (!map->arch)
           break;

      --> the maps are there because the build generated them

           if (!strcmp_cpuid_str(map->cpuid, cpuid)) {
                table = &map->event_table;
                break;
           }
      --> Since no matching CPU string the table var remains 0x0
      }
      free(cpuid);
      if (!pmu)
           return table;

      --> The pmu is "software" so it exists and no return

      --> and here perf dies because table is 0x0
      for (i = 0; i < table->num_pmus; i++) {
	      ...
      }
      return NULL;

Fix this and do not access the table variable. Instead return 0x0
which is the same return code when the for-loop was not successful.

Output after:
 # ./perf stat -e cs -- true

 Performance counter stats for 'true':

                 0      cs

       0.000853105 seconds time elapsed

       0.000061000 seconds user
       0.000827000 seconds sys

 # ./perf stat -e cpu-clock -- true

 Performance counter stats for 'true':

              0.25 msec cpu-clock #    0.341 CPUs utilized

       0.000728383 seconds time elapsed

       0.000055000 seconds user
       0.000706000 seconds sys

 # ./perf stat -e cycles -- true

 Performance counter stats for 'true':

   <not supported>      cycles

       0.000767298 seconds time elapsed

       0.000055000 seconds user
       0.000739000 seconds sys

 #

Fixes: 7c52f10c0d ("perf pmu: Cache JSON events table")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: dengler@linux.ibm.com
Cc: gor@linux.ibm.com
Cc: hca@linux.ibm.com
Cc: sumanthk@linux.ibm.com
Cc: svens@linux.ibm.com
Link: https://lore.kernel.org/r/20230913125157.2790375-1-tmricht@linux.ibm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2023-09-17 15:51:57 -07:00
..
arch tools headers UAPI: Sync files changed by new fchmodat2 and map_shadow_stack syscalls with the kernel sources 2023-09-13 08:24:51 -03:00
bench perf bench sched-seccomp-notify: Use the tools copy of seccomp.h UAPI 2023-09-13 08:49:00 -03:00
dlfilters perf dlfilter: Add al_cleanup() 2023-08-15 16:41:49 -03:00
Documentation perf docs: Fix format of unordered lists 2023-08-16 08:37:49 -03:00
include/perf perf dlfilter: Add al_cleanup() 2023-08-15 16:41:49 -03:00
jvmti
pmu-events perf jevent: fix core dump on software events on s390 2023-09-17 15:51:57 -07:00
python
scripts perf scripts python gecko: Launch the profiler UI on the default browser with the appropriate URL 2023-08-24 14:41:49 -03:00
tests perf parse-events: Fixes relating to no_value terms 2023-09-02 08:12:15 -03:00
trace perf tools changes for v6.6: 2023-09-09 20:06:17 -07:00
ui perf tui slang: Tidy casts 2023-08-25 10:24:55 -03:00
util perf pmu: Ensure all alias variables are initialized 2023-09-17 15:51:42 -07:00
.gitignore perf jevents: Run metric_test.py at compile-time 2023-02-03 17:11:39 -03:00
Build perf script: Fix Python support when no libtraceevent 2023-03-15 10:27:07 -03:00
builtin-annotate.c perf addr_location: Add init/exit/copy functions 2023-06-12 15:57:53 -03:00
builtin-bench.c perf tools changes for v6.6: 2023-09-09 20:06:17 -07:00
builtin-buildid-cache.c
builtin-buildid-list.c perf util: Move input_name to util 2023-04-10 19:21:31 -03:00
builtin-c2c.c perf callchain: Use pthread keys for tls callchain_cursor 2023-06-12 15:57:54 -03:00
builtin-config.c perf path: Make mkpath thread safe, remove 16384 bytes from .bss 2023-05-28 10:24:14 -03:00
builtin-daemon.c perf tools: Add missing else to cmd_daemon subcommand condition 2023-06-27 12:09:44 -07:00
builtin-data.c perf util: Move input_name to util 2023-04-10 19:21:31 -03:00
builtin-diff.c perf diff: Replaces some ',' as separator with the more usual ';' 2023-07-20 11:43:45 -03:00
builtin-evlist.c perf util: Move input_name to util 2023-04-10 19:21:31 -03:00
builtin-ftrace.c perf tools fixes for v6.4: 2nd batch 2023-05-31 15:31:56 -03:00
builtin-help.c perf path: Make mkpath thread safe, remove 16384 bytes from .bss 2023-05-28 10:24:14 -03:00
builtin-inject.c perf inject: Lazily allocate guest_event event_buf 2023-06-12 18:18:14 -03:00
builtin-kallsyms.c perf symbol: Remove now unused symbol_conf.sort_by_name 2023-06-23 21:48:49 -07:00
builtin-kmem.c perf callchain: Use pthread keys for tls callchain_cursor 2023-06-12 15:57:54 -03:00
builtin-kvm.c perf evsel: Introduce evsel__name_is() method to check if the evsel name is equal to a given string 2023-04-24 14:28:11 -03:00
builtin-kwork.c perf callchain: Use pthread keys for tls callchain_cursor 2023-06-12 15:57:54 -03:00
builtin-list.c perf list: Don't print Unit for "default_core" 2023-08-31 16:24:47 -03:00
builtin-lock.c perf lock contention: Fix typo in max-stack option description 2023-08-25 10:27:07 -03:00
builtin-mem.c perf addr_location: Add init/exit/copy functions 2023-06-12 15:57:53 -03:00
builtin-probe.c perf probe: Dynamically allocate params memory 2023-05-28 10:24:02 -03:00
builtin-record.c perf parse-events: Remove BPF event support 2023-08-15 16:41:48 -03:00
builtin-report.c perf symbol: Remove now unused symbol_conf.sort_by_name 2023-06-23 21:48:49 -07:00
builtin-sched.c perf sched: Avoid large stack allocations 2023-06-12 18:18:14 -03:00
builtin-script.c perf script: Print "cgroup" field on the same line as "comm" 2023-08-08 11:21:11 -03:00
builtin-stat.c perf stat: Add missing newline in pr_err messages 2023-06-20 15:55:13 -07:00
builtin-timechart.c perf addr_location: Add init/exit/copy functions 2023-06-12 15:57:53 -03:00
builtin-top.c perf top: Don't pass an ERR_PTR() directly to perf_session__delete() 2023-08-17 14:13:04 -03:00
builtin-trace.c perf trace: Use heuristic when deciding if a syscall tracepoint "const char *" field is really a string 2023-08-18 16:33:28 -03:00
builtin-version.c Revert "perf build: Make BUILD_BPF_SKEL default, rename to NO_BPF_SKEL" 2023-05-06 18:07:37 -03:00
builtin.h perf usage: Move usage strings 2023-04-10 19:20:53 -03:00
check-headers.sh tools headers UAPI: Copy seccomp.h to be able to build 'perf bench' in older systems 2023-09-13 08:48:48 -03:00
command-list.txt
CREDITS
design.txt
Makefile
Makefile.config perf parse-events: Remove BPF event support 2023-08-15 16:41:48 -03:00
Makefile.perf perf build: Allow customization of clang options for BPF target 2023-08-23 15:33:18 -03:00
MANIFEST
perf-archive.sh
perf-completion.sh perf tools: Fix auto-complete on aarch64 2023-02-08 10:38:10 -03:00
perf-iostat.sh
perf-read-vdso.c
perf-sys.h
perf.c perf parse-events: Remove BPF event support 2023-08-15 16:41:48 -03:00
perf.h perf util: Move perf_guest/host declarations 2023-04-10 19:22:05 -03:00