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Hallyn" , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH] drivers/perf: arm_spe: Use perf_allow_kernel() for permissions Date: Wed, 7 Aug 2024 11:54:41 +0100 Message-Id: <20240807105441.2156738-1-james.clark@linaro.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Signed-off-by: James Clark --- drivers/perf/arm_spe_pmu.c | 9 ++++----- kernel/events/core.c | 1 + security/security.c | 1 + 3 files changed, 6 insertions(+), 5 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 @@ =20 /* * 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= ) =3D=3D SPE_PMU_HW_FLAGS_C =20 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->at= tr)) event->hw.flags |=3D SPE_PMU_HW_FLAGS_CX; } =20 @@ -745,9 +745,8 @@ static int arm_spe_pmu_event_init(struct perf_event *ev= ent) =20 set_spe_event_has_cx(event); reg =3D 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); =20 return 0; } diff --git a/kernel/events/core.c b/kernel/events/core.c index aa3450bdc227..4a69583e329a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -417,6 +417,7 @@ static struct kmem_cache *perf_event_cache; * 2 - disallow kernel profiling for unpriv */ int sysctl_perf_event_paranoid __read_mostly =3D 2; +EXPORT_SYMBOL_GPL(sysctl_perf_event_paranoid); =20 /* Minimum for 512 kiB + 1 user control page */ int sysctl_perf_event_mlock __read_mostly =3D 512 + (PAGE_SIZE / 1024); /*= 'free' kiB per user */ diff --git a/security/security.c b/security/security.c index 8cee5b6c6e6d..70cc9206e902 100644 --- a/security/security.c +++ b/security/security.c @@ -5610,6 +5610,7 @@ int security_perf_event_open(struct perf_event_attr *= attr, int type) { return call_int_hook(perf_event_open, attr, type); } +EXPORT_SYMBOL_GPL(security_perf_event_open); =20 /** * security_perf_event_alloc() - Allocate a perf event LSM blob --=20 2.34.1