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perf: Disallow user-space callchains for function trace events

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Recent issues with user space callchains processing within
page fault handler tracing showed as Peter said 'there's
just too much fail surface'.

Related list discussions:

  http://marc.info/?t=139302086500001&r=1&w=2
  http://marc.info/?t=139301437300003&r=1&w=2

Suggested-by: Peter Zijlstra <[email protected]>
Signed-off-by: Jiri Olsa <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Vince Weaver <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Jiri Olsa authored and Ingo Molnar committed 2014-03-11 11:57:57 +01:00
1 parent ef11dadb83
commit cfa77bc4af
1 file changed
+12 -3
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kernel/trace/trace_event_perf.c
+12 -3
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@@ -31,9 +31,18 @@ static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
}
/* The ftrace function trace is allowed only for root. */
if (ftrace_event_is_function(tp_event) &&
perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
return -EPERM;
if (ftrace_event_is_function(tp_event)) {
if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
return -EPERM;
/*
* We don't allow user space callchains for function trace
* event, due to issues with page faults while tracing page
* fault handler and its overall trickiness nature.
*/
if (!p_event->attr.exclude_callchain_user)
return -EINVAL;
}
/* No tracing, just counting, so no obvious leak */
if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))