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authorMark Rutland <mark.rutland@arm.com>2023-12-04 14:58:47 +0300
committerWill Deacon <will@kernel.org>2023-12-05 15:34:24 +0300
commitca6f537e459e2da4b331fe8928d1a0b0f9301f42 (patch)
tree0b3bfcf33c5f00f7b0255e265b26348508625a11 /drivers/perf
parent877806b9b41ea371defaaf58d815320f1a76384f (diff)
downloadlinux-ca6f537e459e2da4b331fe8928d1a0b0f9301f42.tar.xz
drivers/perf: pmuv3: don't expose SW_INCR event in sysfs
The SW_INCR event is somewhat unusual, and depends on the specific HW counter that it is programmed into. When programmed into PMEVCNTR<n>, SW_INCR will count any writes to PMSWINC_EL0 with bit n set, ignoring writes to SW_INCR with bit n clear. Event rotation means that there's no fixed relationship between perf_events and HW counters, so this isn't all that useful. Further, we program PMUSERENR.{SW,EN}=={0,0}, which causes EL0 writes to PMSWINC_EL0 to be trapped and handled as UNDEFINED, resulting in a SIGILL to userspace. Given that, it's not a good idea to expose SW_INCR in sysfs. Hide it as we did for CHAIN back in commit: 4ba2578fa7b55701 ("arm64: perf: don't expose CHAIN event in sysfs") Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20231204115847.2993026-1-mark.rutland@arm.com Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'drivers/perf')
-rw-r--r--drivers/perf/arm_pmuv3.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index c136a6529014..bbde60f1b08c 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -169,7 +169,11 @@ armv8pmu_events_sysfs_show(struct device *dev,
PMU_EVENT_ATTR_ID(name, armv8pmu_events_sysfs_show, config)
static struct attribute *armv8_pmuv3_event_attrs[] = {
- ARMV8_EVENT_ATTR(sw_incr, ARMV8_PMUV3_PERFCTR_SW_INCR),
+ /*
+ * Don't expose the sw_incr event in /sys. It's not usable as writes to
+ * PMSWINC_EL0 will trap as PMUSERENR.{SW,EN}=={0,0} and event rotation
+ * means we don't have a fixed event<->counter relationship regardless.
+ */
ARMV8_EVENT_ATTR(l1i_cache_refill, ARMV8_PMUV3_PERFCTR_L1I_CACHE_REFILL),
ARMV8_EVENT_ATTR(l1i_tlb_refill, ARMV8_PMUV3_PERFCTR_L1I_TLB_REFILL),
ARMV8_EVENT_ATTR(l1d_cache_refill, ARMV8_PMUV3_PERFCTR_L1D_CACHE_REFILL),