From 6cede11149bf9ebb095c6b53e3ac3365b295a2ad Mon Sep 17 00:00:00 2001 From: Thomas Richter Date: Wed, 21 Apr 2021 14:04:00 +0200 Subject: [PATCH] perf ftrace: Fix access to pid in array when setting a pid filter [ 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 Signed-off-by: Thomas Richter Acked-by: Namhyung Kim Cc: Heiko Carstens Cc: Sumanth Korikkar Cc: Sven Schnelle Cc: Vasily Gorbik Link: http://lore.kernel.org/lkml/20210421120400.2126433-1-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- 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; }