perf ftrace: Fix access to pid in array when setting a pid filter
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.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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