Commit-ID: cfa77bc4af2c75c0781ee76cde2dd104c6c8e2b7 Gitweb: http://git.kernel.org/tip/cfa77bc4af2c75c0781ee76cde2dd104c6c8e2b7 Author: Jiri Olsa <jolsa@xxxxxxxxxx> AuthorDate: Sun, 2 Mar 2014 16:56:38 +0100 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Tue, 11 Mar 2014 11:57:57 +0100 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 <a.p.zijlstra@xxxxxxxxx> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Vince Weaver <vincent.weaver@xxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1393775800-13524-2-git-send-email-jolsa@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/trace/trace_event_perf.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index e854f42..d5e01c3 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)) -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html