Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 regression fix from Will Deacon:
 "Apologies for the _extremely_ late pull request here, but we had a
  'perf' (i.e. CPU PMU) regression on the Apple M1 reported on Wednesday
  [1] which was introduced by bd2756811766 ("perf: Rewrite core context
  handling") during the merge window.

  Mark and I looked into this and noticed an additional problem caused
  by the same patch, where the 'CHAIN' event (used to combine two
  adjacent 32-bit counters into a single 64-bit counter) was not being
  filtered correctly. Mark posted a series on Thursday [2] which
  addresses both of these regressions and I queued it the same day.

  The changes are small, self-contained and have been confirmed to fix
  the original regression.

  Summary:

   - Fix 'perf' regression for non-standard CPU PMU hardware (i.e. Apple
     M1)"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: perf: reject CHAIN events at creation time
  arm_pmu: fix event CPU filtering

1 files changed, 8 insertions, 7 deletions

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index a5193f2146a6..dde06c0f97f3 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1023,12 +1023,6 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
 	return 0;
 }
 
-static bool armv8pmu_filter(struct pmu *pmu, int cpu)
-{
-	struct arm_pmu *armpmu = to_arm_pmu(pmu);
-	return !cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus);
-}
-
 static void armv8pmu_reset(void *info)
 {
 	struct arm_pmu *cpu_pmu = (struct arm_pmu *)info;
@@ -1069,6 +1063,14 @@ static int __armv8_pmuv3_map_event(struct perf_event *event,
 				       &armv8_pmuv3_perf_cache_map,
 				       ARMV8_PMU_EVTYPE_EVENT);
 
+	/*
+	 * CHAIN events only work when paired with an adjacent counter, and it
+	 * never makes sense for a user to open one in isolation, as they'll be
+	 * rotated arbitrarily.
+	 */
+	if (hw_event_id == ARMV8_PMUV3_PERFCTR_CHAIN)
+		return -EINVAL;
+
 	if (armv8pmu_event_is_64bit(event))
 		event->hw.flags |= ARMPMU_EVT_64BIT;
 
@@ -1258,7 +1260,6 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu, char *name,
 	cpu_pmu->stop			= armv8pmu_stop;
 	cpu_pmu->reset			= armv8pmu_reset;
 	cpu_pmu->set_event_filter	= armv8pmu_set_event_filter;
-	cpu_pmu->filter			= armv8pmu_filter;
 
 	cpu_pmu->pmu.event_idx		= armv8pmu_user_event_idx;