perf: Limit perf_event_attr::sample_period to 63 bits
authorPeter Zijlstra <peterz@infradead.org>
Thu, 15 May 2014 18:23:48 +0000 (20:23 +0200)
committerJiri Slaby <jslaby@suse.cz>
Fri, 20 Jun 2014 15:33:52 +0000 (17:33 +0200)
commited8acba3f62f4cb479628215582b487872c398d7
tree68f5ce0a88df09a943baf0ae08bcf2e9b35afc57
parente36e8c8f72bc4f8309bf0dea92d58aa661c74c84
perf: Limit perf_event_attr::sample_period to 63 bits

commit 0819b2e30ccb93edf04876237b6205eef84ec8d2 upstream.

Vince reported that using a large sample_period (one with bit 63 set)
results in wreckage since while the sample_period is fundamentally
unsigned (negative periods don't make sense) the way we implement
things very much rely on signed logic.

So limit sample_period to 63 bits to avoid tripping over this.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-p25fhunibl4y3qi0zuqmyf4b@git.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
kernel/events/core.c