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authorSuzuki K. Poulose <suzuki.poulose@arm.com>2015-03-17 21:15:00 +0300
committerWill Deacon <will.deacon@arm.com>2015-03-27 16:44:11 +0300
commitb1862199be6098855b598b69f5098d2fb4cecfcb (patch)
treec91684b61d6b94c74e77359175a2726e1d0262b1 /drivers/bus
parent06e5801b8cb3fc057d88cb4dc03c0b64b2744cda (diff)
downloadlinux-b1862199be6098855b598b69f5098d2fb4cecfcb.tar.xz
drivers: cci: reject groups spanning multiple HW PMUs
The perf core implicitly rejects events spanning multiple HW PMUs, as in these cases the event->ctx will differ. However this validation is performed after pmu::event_init() is called in perf_init_event(), and thus pmu::event_init() may be called with a group leader from a different HW PMU. The CCI PMU driver does not take this fact into account, and assumes that the any other hardware event belongs to the CCI. There are two issues with it : 1) It is wrong and we should reject such groups. 2) Validation allocates an temporary idx for this non-cci event, which leads to wrong calculation of the counter availability, and eventually lesser number of events in the group. This patch updates the CCI PMU driver to first test for and reject events from other PMUs, which is the right thing to do. Cc: Will Deacon <will.deacon@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Ziljstra (Intel) <peterz@infradead.org> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'drivers/bus')
-rw-r--r--drivers/bus/arm-cci.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 84fd66057dad..68ef6f2aa24d 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -660,12 +660,21 @@ static void cci_pmu_del(struct perf_event *event, int flags)
}
static int
-validate_event(struct cci_pmu_hw_events *hw_events,
- struct perf_event *event)
+validate_event(struct pmu *cci_pmu,
+ struct cci_pmu_hw_events *hw_events,
+ struct perf_event *event)
{
if (is_software_event(event))
return 1;
+ /*
+ * Reject groups spanning multiple HW PMUs (e.g. CPU + CCI). The
+ * core perf code won't check that the pmu->ctx == leader->ctx
+ * until after pmu->event_init(event).
+ */
+ if (event->pmu != cci_pmu)
+ return 0;
+
if (event->state < PERF_EVENT_STATE_OFF)
return 1;
@@ -687,15 +696,15 @@ validate_group(struct perf_event *event)
.used_mask = CPU_BITS_NONE,
};
- if (!validate_event(&fake_pmu, leader))
+ if (!validate_event(event->pmu, &fake_pmu, leader))
return -EINVAL;
list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
- if (!validate_event(&fake_pmu, sibling))
+ if (!validate_event(event->pmu, &fake_pmu, sibling))
return -EINVAL;
}
- if (!validate_event(&fake_pmu, event))
+ if (!validate_event(event->pmu, &fake_pmu, event))
return -EINVAL;
return 0;