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ARM: 7809/1: perf: fix event validation for software group leaders

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commit c95eb3184e upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Will Deacon 2013-08-07 23:39:41 +01:00 committed by Greg Kroah-Hartman
parent ca4e6a5600
commit 40c366017f
1 changed files with 3 additions and 0 deletions
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3
arch/arm/kernel/perf_event.c
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@ -324,6 +324,9 @@ validate_event(struct pmu_hw_events *hw_events,
struct hw_perf_event fake_event = event->hw;
struct pmu *leader_pmu = event->group_leader->pmu;
if (is_software_event(event))
return 1;
if (event->pmu != leader_pmu || event->state < PERF_EVENT_STATE_OFF)
return 1;