From 4ba2578fa7b557012b8f59ad7a9284ff15394338 Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Mon, 25 Apr 2016 15:05:24 +0100
Subject: [PATCH] arm64: perf: don't expose CHAIN event in sysfs
The CHAIN event allows two 32-bit counters to be treated as a single
64-bit counter, under certain allocation restrictions on the PMU.
Whilst userspace could theoretically create CHAIN events using the raw
event syntax, we don't really want to advertise this in sysfs, since
it's useless in isolation. This patch removes the event from our /sys
entries.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/perf_event.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index ca6beb10b5923..838ccf123307d 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -416,7 +416,7 @@ ARMV8_EVENT_ATTR(memory_error, ARMV8_PMUV3_PERFCTR_MEMORY_ERROR);
ARMV8_EVENT_ATTR(inst_spec, ARMV8_PMUV3_PERFCTR_INST_SPEC);
ARMV8_EVENT_ATTR(ttbr_write_retired, ARMV8_PMUV3_PERFCTR_TTBR_WRITE_RETIRED);
ARMV8_EVENT_ATTR(bus_cycles, ARMV8_PMUV3_PERFCTR_BUS_CYCLES);
-ARMV8_EVENT_ATTR(chain, ARMV8_PMUV3_PERFCTR_CHAIN);
+/* Don't expose the chain event in /sys, since it's useless in isolation */
ARMV8_EVENT_ATTR(l1d_cache_allocate, ARMV8_PMUV3_PERFCTR_L1D_CACHE_ALLOCATE);
ARMV8_EVENT_ATTR(l2d_cache_allocate, ARMV8_PMUV3_PERFCTR_L2D_CACHE_ALLOCATE);
ARMV8_EVENT_ATTR(br_retired, ARMV8_PMUV3_PERFCTR_BR_RETIRED);
@@ -467,7 +467,6 @@ static struct attribute *armv8_pmuv3_event_attrs[] = {
&armv8_event_attr_inst_spec.attr.attr,
&armv8_event_attr_ttbr_write_retired.attr.attr,
&armv8_event_attr_bus_cycles.attr.attr,
- &armv8_event_attr_chain.attr.attr,
&armv8_event_attr_l1d_cache_allocate.attr.attr,
&armv8_event_attr_l2d_cache_allocate.attr.attr,
&armv8_event_attr_br_retired.attr.attr,
--
2.30.2