From: Thomas Richter tmricht@linux.ibm.com
[ Upstream commit 671b60cb6a897a5b3832fe57657152f2c3995e25 ]
Command 'perf ftrace -v -- ls' fails in s390 (at least 5.12.0rc6).
The root cause is a missing pointer dereference which causes an array element address to be used as PID.
Fix this by extracting the PID.
Output before: # ./perf ftrace -v -- ls function_graph tracer is used write '-263732416' to tracing/set_ftrace_pid failed: Invalid argument failed to set ftrace pid #
Output after: ./perf ftrace -v -- ls function_graph tracer is used # tracer: function_graph # # CPU DURATION FUNCTION CALLS # | | | | | | | 4) | rcu_read_lock_sched_held() { 4) 0.552 us | rcu_lockdep_current_cpu_online(); 4) 6.124 us | }
Reported-by: Alexander Schmidt alexschm@de.ibm.com Signed-off-by: Thomas Richter tmricht@linux.ibm.com Acked-by: Namhyung Kim namhyung@kernel.org Cc: Heiko Carstens hca@linux.ibm.com Cc: Sumanth Korikkar sumanthk@linux.ibm.com Cc: Sven Schnelle svens@linux.ibm.com Cc: Vasily Gorbik gor@linux.ibm.com Link: http://lore.kernel.org/lkml/20210421120400.2126433-1-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/builtin-ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index d5adc417a4ca..40b179f54428 100644 --- a/tools/perf/builtin-ftrace.c +++ b/tools/perf/builtin-ftrace.c @@ -161,7 +161,7 @@ static int set_tracing_pid(struct perf_ftrace *ftrace)
for (i = 0; i < perf_thread_map__nr(ftrace->evlist->core.threads); i++) { scnprintf(buf, sizeof(buf), "%d", - ftrace->evlist->core.threads->map[i]); + perf_thread_map__pid(ftrace->evlist->core.threads, i)); if (append_tracing_file("set_ftrace_pid", buf) < 0) return -1; }