This is a note to let you know that I've just added the patch titled
drivers/perf: arm_spe: Use perf_allow_kernel() for permissions
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drivers-perf-arm_spe-use-perf_allow_kernel-for-permi.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7269f5311f2fb6cdf3bdb53e22be48f5fa9c0acb
Author: James Clark <james.clark@xxxxxxxxxx>
Date: Tue Aug 27 15:51:12 2024 +0100
drivers/perf: arm_spe: Use perf_allow_kernel() for permissions
[ Upstream commit 5e9629d0ae977d6f6916d7e519724804e95f0b07 ]
Use perf_allow_kernel() for 'pa_enable' (physical addresses),
'pct_enable' (physical timestamps) and context IDs. This means that
perf_event_paranoid is now taken into account and LSM hooks can be used,
which is more consistent with other perf_event_open calls. For example
PERF_SAMPLE_PHYS_ADDR uses perf_allow_kernel() rather than just
perfmon_capable().
This also 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@xxxxxxx>
Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240827145113.1224604-1-james.clark@xxxxxxxxxx
Link: https://lore.kernel.org/all/20240807120039.GD37996@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index d2b0cbf0e0c41..2bec2e3af0bd6 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;
}
@@ -767,9 +767,8 @@ 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 95d4118ee4a91..7a5563ffe61b5 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1599,13 +1599,7 @@ 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 4d0abdace4e7c..d40809bdf4b30 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -13330,6 +13330,15 @@ 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.
*
