From: James Clark james.clark@linaro.org
[ 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@arm.com Signed-off-by: James Clark james.clark@linaro.org Link: https://lore.kernel.org/r/20240827145113.1224604-1-james.clark@linaro.org Link: https://lore.kernel.org/all/20240807120039.GD37996@noisy.programming.kicks-a... Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 9100d82bfabc0..3569050f9cf37 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 1a8942277ddad..e336306b8c08e 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 8a6c6bbcd658a..b21c8f24a9876 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -13358,6 +13358,15 @@ 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. *