Commit f967140d authored by Kim Phillips's avatar Kim Phillips Committed by Borislav Petkov
Browse files

perf/amd/uncore: Replace manual sampling check with CAP_NO_INTERRUPT flag 



Enable the sampling check in kernel/events/core.c::perf_event_open(),
which returns the more appropriate -EOPNOTSUPP.

BEFORE:

  $ sudo perf record -a -e instructions,l3_request_g1.caching_l3_cache_accesses true
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (l3_request_g1.caching_l3_cache_accesses).
  /bin/dmesg | grep -i perf may provide additional information.

With nothing relevant in dmesg.

AFTER:

  $ sudo perf record -a -e instructions,l3_request_g1.caching_l3_cache_accesses true
  Error:
  l3_request_g1.caching_l3_cache_accesses: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'

Fixes: c43ca509 ("perf/x86/amd: Add support for AMD NB and L2I "uncore" counters")
Signed-off-by: default avatarKim Phillips <kim.phillips@amd.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200311191323.13124-1-kim.phillips@amd.com
parent 798048f8

arch/x86/events/amd/uncore.c

+7 −10
Original line number Diff line number Diff line
@@ -190,15 +190,12 @@ static int amd_uncore_event_init(struct perf_event *event) 


	/*

	 * NB and Last level cache counters (MSRs) are shared across all cores

	 * that share the same NB / Last level cache. Interrupts can be directed

	 * to a single target core, however, event counts generated by processes

	 * running on other cores cannot be masked out. So we do not support

	 * sampling and per-thread events.

	 * that share the same NB / Last level cache.  On family 16h and below,

	 * Interrupts can be directed to a single target core, however, event

	 * counts generated by processes running on other cores cannot be masked

	 * out. So we do not support sampling and per-thread events via

	 * CAP_NO_INTERRUPT, and we do not enable counter overflow interrupts:

	 */

	if (is_sampling_event(event) || event->attach_state & PERF_ATTACH_TASK)

		return -EINVAL;



	/* and we do not enable counter overflow interrupts */

	hwc->config = event->attr.config & AMD64_RAW_EVENT_MASK_NB;

	hwc->idx = -1;
@@ -306,7 +303,7 @@ static struct pmu amd_nb_pmu = { 
	.start		= amd_uncore_start,

	.stop		= amd_uncore_stop,

	.read		= amd_uncore_read,

	.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,

	.capabilities	= PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_NO_INTERRUPT,

};



static struct pmu amd_llc_pmu = {
@@ -317,7 +314,7 @@ static struct pmu amd_llc_pmu = { 
	.start		= amd_uncore_start,

	.stop		= amd_uncore_stop,

	.read		= amd_uncore_read,

	.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,

	.capabilities	= PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_NO_INTERRUPT,

};



static struct amd_uncore *amd_uncore_alloc(unsigned int cpu)

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