Hey all, most "advanced" perf tools can be used as a normal non-root user after executing the following commands:
sudo mount -o remount,mode=755 /sys/kernel/debug/
sudo mount -o remount,mode=755 /sys/kernel/debug/tracing
echo "-1" | sudo tee /proc/sys/kernel/perf_event_paranoid
The exception here are dynamic tracepoints:
perf probe -x /lib64/libc.so.6 malloc
Failed to open uprobe_events: Permission denied
Error: Failed to add events.
Strace shows that it fails to write to /sys/kernel/debug/tracing/
uprobe_events. I could workaround this issue with a
sudo chmod a+w -R /sys/kernel/debug/tracing/uprobe_events
Is that "OK", or a very bad idea? Is there a better alternative? Furthermore,
I notice that I cannot delete the trace points:
perf probe -l
probe_libc:malloc (on __malloc in /usr/lib/libc-2.22.so)
debug perf probe -d probe_libc:malloc
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff5f73160 in feof () from /usr/lib/libc.so.6
(gdb) bt
#0 0x00007ffff5f73160 in feof () from /usr/lib/libc.so.6
#1 0x000000000050c9d3 in probe_file__get_rawlist (fd=<optimized out>) at
util/probe-file.c:144
#2 0x000000000050cab1 in __probe_file__get_namelist (fd=<optimized out>,
include_group=include_group@entry=true)
at util/probe-file.c:173
#3 0x000000000050cd90 in probe_file__get_events (fd=<optimized out>,
filter=filter@entry=0x1745b50,
plist=plist@entry=0x17457b0) at util/probe-file.c:274
#4 0x000000000046184f in perf_del_probe_events (filter=0x1745b50) at builtin-
probe.c:386
#5 __cmd_probe (argc=<optimized out>, argv=argv@entry=0x7fffffffcb90,
prefix=<optimized out>) at builtin-probe.c:596
#6 0x0000000000461c8c in cmd_probe (argc=<optimized out>,
argv=0x7fffffffcb90, prefix=<optimized out>)
at builtin-probe.c:627
#7 0x0000000000486923 in run_builtin (p=p@entry=0x6a9cc0 <commands+384>,
argc=argc@entry=3, argv=argv@entry=0x7fffffffcb90)
at perf.c:371
#8 0x000000000042cce2 in handle_internal_command (argv=0x7fffffffcb90,
argc=3) at perf.c:431
#9 run_argv (argv=0x7fffffffc920, argcp=0x7fffffffc92c) at perf.c:475
#10 main (argc=3, argv=0x7fffffffcb90) at perf.c:592
Any idea what might be going on here? I get the same crash when trying this as
root.
Bye
--
Milian Wolff | [email protected] | Software Engineer
KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt Experts
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