Commit 9f6b28d4 authored Dec 06, 2020 by Linus Torvalds

Merge tag 'perf-urgent-2020-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Thomas Gleixner:
 "Two fixes for performance monitoring on X86:

   - Add recursion protection to another callchain invoked from
     x86_pmu_stop() which can recurse back into x86_pmu_stop(). The
     first attempt to fix this missed this extra code path.

   - Use the already filtered status variable to check for PEBS counter
     overflow bits and not the unfiltered full status read from
     IA32_PERF_GLOBAL_STATUS which can have unrelated bits check which
     would be evaluated incorrectly"

* tag 'perf-urgent-2020-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel: Check PEBS status correctly
  perf/x86/intel: Fix a warning on x86_pmu_stop() with large PEBS

parents 592d9a08 fc17db8a

arch/x86/events/intel/ds.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1916,7 +1916,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs, struct perf_sample_d
		* that caused the PEBS record. It's called collision.
		* If collision happened, the record will be dropped.
		*/
		if (p->status != (1ULL << bit)) {
		if (pebs_status != (1ULL << bit)) {
		for_each_set_bit(i, (unsigned long *)&pebs_status, size)
		error[i]++;
		continue;
		@@ -1940,7 +1940,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs, struct perf_sample_d
		if (error[bit]) {
		perf_log_lost_samples(event, error[bit]);

		if (perf_event_account_interrupt(event))
		if (iregs && perf_event_account_interrupt(event))
		x86_pmu_stop(event, 0);
		}

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