ARM: 7809/1: perf: fix event validation for software group leaders
authorWill Deacon <will.deacon@arm.com>
Wed, 7 Aug 2013 22:39:41 +0000 (23:39 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Tue, 13 Aug 2013 19:21:43 +0000 (20:21 +0100)
commitc95eb3184ea1a3a2551df57190c81da695e2144b
tree7cf42626f642a42d72cce07fe98bdc2afd227d2f
parent2ba85e7af4c639d933c9a87a6d7363f2983d5ada
ARM: 7809/1: perf: fix event validation for software group leaders

It is possible to construct an event group with a software event as a
group leader and then subsequently add a hardware event to the group.
This results in the event group being validated by adding all members
of the group to a fake PMU and attempting to allocate each event on
their respective PMU.

Unfortunately, for software events wthout a corresponding arm_pmu, this
results in a kernel crash attempting to dereference the ->get_event_idx
function pointer.

This patch fixes the problem by checking explicitly for software events
and ignoring those in event validation (since they can always be
scheduled). We will probably want to revisit this for 3.12, since the
validation checks don't appear to work correctly when dealing with
multiple hardware PMUs anyway.

Cc: <stable@vger.kernel.org>
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arch/arm/kernel/perf_event.c