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Message-Id: <20240807155153.2714025-1-james.clark@linaro.org>
Date: Wed, 7 Aug 2024 16:51:53 +0100
From: James Clark <james.clark@...aro.org>
To: linux-arm-kernel@...ts.infradead.org,
peterz@...radead.org
Cc: James Clark <james.clark@...aro.org>,
Al Grant <al.grant@....com>,
Will Deacon <will@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
"Liang, Kan" <kan.liang@...ux.intel.com>,
linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: [PATCH v2] drivers/perf: arm_spe: Use perf_allow_kernel() for permissions
For other PMUs, PERF_SAMPLE_PHYS_ADDR requires perf_allow_kernel()
rather than just perfmon_capable(). Because PMSCR_EL1_PA is another form
of physical address, make it consistent and use perf_allow_kernel() for
SPE as well. PMSCR_EL1_PCT and PMSCR_EL1_CX also get the same change.
This improves consistency and indirectly fixes the following error
message which is misleading because perf_event_paranoid is not taken
into account by perfmon_capable():
$ perf record -e arm_spe/pa_enable/
Error:
Access to performance monitoring and observability operations is
limited. Consider adjusting /proc/sys/kernel/perf_event_paranoid
setting ...
Suggested-by: Al Grant <al.grant@....com>
Signed-off-by: James Clark <james.clark@...aro.org>
---
Changes since v1:
* Export perf_allow_kernel() instead of sysctl_perf_event_paranoid
drivers/perf/arm_spe_pmu.c | 9 ++++-----
include/linux/perf_event.h | 8 +-------
kernel/events/core.c | 9 +++++++++
3 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index 9100d82bfabc..3569050f9cf3 100644
--- a/drivers/perf/arm_spe_pmu.c
+++ b/drivers/perf/arm_spe_pmu.c
@@ -41,7 +41,7 @@
/*
* Cache if the event is allowed to trace Context information.
- * This allows us to perform the check, i.e, perfmon_capable(),
+ * This allows us to perform the check, i.e, perf_allow_kernel(),
* in the context of the event owner, once, during the event_init().
*/
#define SPE_PMU_HW_FLAGS_CX 0x00001
@@ -50,7 +50,7 @@ static_assert((PERF_EVENT_FLAG_ARCH & SPE_PMU_HW_FLAGS_CX) == SPE_PMU_HW_FLAGS_C
static void set_spe_event_has_cx(struct perf_event *event)
{
- if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && perfmon_capable())
+ if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && !perf_allow_kernel(&event->attr))
event->hw.flags |= SPE_PMU_HW_FLAGS_CX;
}
@@ -745,9 +745,8 @@ static int arm_spe_pmu_event_init(struct perf_event *event)
set_spe_event_has_cx(event);
reg = arm_spe_event_to_pmscr(event);
- if (!perfmon_capable() &&
- (reg & (PMSCR_EL1_PA | PMSCR_EL1_PCT)))
- return -EACCES;
+ if (reg & (PMSCR_EL1_PA | PMSCR_EL1_PCT))
+ return perf_allow_kernel(&event->attr);
return 0;
}
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 1a8942277dda..e336306b8c08 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1602,13 +1602,7 @@ static inline int perf_is_paranoid(void)
return sysctl_perf_event_paranoid > -1;
}
-static inline int perf_allow_kernel(struct perf_event_attr *attr)
-{
- if (sysctl_perf_event_paranoid > 1 && !perfmon_capable())
- return -EACCES;
-
- return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
-}
+int perf_allow_kernel(struct perf_event_attr *attr);
static inline int perf_allow_cpu(struct perf_event_attr *attr)
{
diff --git a/kernel/events/core.c b/kernel/events/core.c
index aa3450bdc227..ae7d63c0c593 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -13351,6 +13351,15 @@ const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
return &event->attr;
}
+int perf_allow_kernel(struct perf_event_attr *attr)
+{
+ if (sysctl_perf_event_paranoid > 1 && !perfmon_capable())
+ return -EACCES;
+
+ return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
+}
+EXPORT_SYMBOL_GPL(perf_allow_kernel);
+
/*
* Inherit an event from parent task to child task.
*
--
2.34.1
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