From: Jiri Olsa Date: Sun, 2 Mar 2014 15:56:38 +0000 (+0100) Subject: perf: Disallow user-space callchains for function trace events X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=cfa77bc4af2c;p=linux-beck.git perf: Disallow user-space callchains for function trace events 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 Signed-off-by: Jiri Olsa Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: "H. Peter Anvin" Cc: Vince Weaver Cc: Steven Rostedt Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1393775800-13524-2-git-send-email-jolsa@redhat.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index e854f420e033..d5e01c3f4e69 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -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))