From: Thomas Richter <tmricht@linux.ibm.com>
To: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
acme@kernel.org
Cc: svens@linux.ibm.com, gor@linux.ibm.com, sumanthk@linux.ibm.com,
hca@linux.ibm.com, Thomas Richter <tmricht@linux.ibm.com>
Subject: [PATCH] perf ftrace: Command fails on s390
Date: Fri, 9 Apr 2021 10:09:12 +0200 [thread overview]
Message-ID: <20210409080912.2960595-1-tmricht@linux.ibm.com> (raw)
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 | }
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
---
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 d49448a1060c..87cb11a7a3ee 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -289,7 +289,7 @@ 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;
}
--
2.30.2
reply other threads:[~2021-04-09 8:09 UTC|newest]
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