From: James Clark <james.clark@arm.com> To: coresight@lists.linaro.org, hejunhao3@huawei.com, suzuki.poulose@arm.com Cc: James Clark <james.clark@arm.com>, Mike Leach <mike.leach@linaro.org>, Leo Yan <leo.yan@linaro.org>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] coresight: Fix crash when Perf and sysfs modes are used concurrently Date: Fri, 6 Oct 2023 14:14:52 +0100 [thread overview] Message-ID: <20231006131452.646721-1-james.clark@arm.com> (raw) Partially revert the change in commit 6148652807ba ("coresight: Enable and disable helper devices adjacent to the path") which changed the bare call from source_ops(csdev)->enable() to coresight_enable_source() for Perf sessions. It was missed that coresight_enable_source() is specifically for the sysfs interface, rather than being a generic call. This interferes with the sysfs reference counting to cause the following crash: $ perf record -e cs_etm/@tmc_etr0/ -C 0 & $ echo 1 > /sys/bus/coresight/devices/tmc_etr0/enable_sink $ echo 1 > /sys/bus/coresight/devices/etm0/enable_source $ echo 0 > /sys/bus/coresight/devices/etm0/enable_source Unable to handle kernel NULL pointer dereference at virtual address 00000000000001d0 Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP ... Call trace: etm4_disable+0x54/0x150 [coresight_etm4x] coresight_disable_source+0x6c/0x98 [coresight] coresight_disable+0x74/0x1c0 [coresight] enable_source_store+0x88/0xa0 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2dc/0x3b0 ksys_write+0x70/0x108 __arm64_sys_write+0x24/0x38 invoke_syscall+0x50/0x128 el0_svc_common.constprop.0+0x104/0x130 do_el0_svc+0x40/0xb8 el0_svc+0x2c/0xb8 el0t_64_sync_handler+0xc0/0xc8 el0t_64_sync+0x1a4/0x1a8 Code: d53cd042 91002000 b9402a81 b8626800 (f940ead5) ---[ end trace 0000000000000000 ]--- This commit linked below also fixes the issue, but has unlocked updates to the mode which could potentially race. So until we come up with a more complete solution that takes all locking and interaction between both modes into account, just revert back to the old behavior for Perf. Reported-by: Junhao He <hejunhao3@huawei.com> Closes: https://lore.kernel.org/linux-arm-kernel/20230921132904.60996-1-hejunhao3@huawei.com/ Fixes: 6148652807ba ("coresight: Enable and disable helper devices adjacent to the path") Signed-off-by: James Clark <james.clark@arm.com> --- drivers/hwtracing/coresight/coresight-etm-perf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 5ca6278baff4..89e8ed214ea4 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -493,7 +493,7 @@ static void etm_event_start(struct perf_event *event, int flags) goto fail_end_stop; /* Finally enable the tracer */ - if (coresight_enable_source(csdev, CS_MODE_PERF, event)) + if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF)) goto fail_disable_path; /* @@ -587,7 +587,7 @@ static void etm_event_stop(struct perf_event *event, int mode) return; /* stop tracer */ - coresight_disable_source(csdev, event); + source_ops(csdev)->disable(csdev, event); /* tell the core */ event->hw.state = PERF_HES_STOPPED; -- 2.34.1
WARNING: multiple messages have this Message-ID (diff)
From: James Clark <james.clark@arm.com> To: coresight@lists.linaro.org, hejunhao3@huawei.com, suzuki.poulose@arm.com Cc: James Clark <james.clark@arm.com>, Mike Leach <mike.leach@linaro.org>, Leo Yan <leo.yan@linaro.org>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] coresight: Fix crash when Perf and sysfs modes are used concurrently Date: Fri, 6 Oct 2023 14:14:52 +0100 [thread overview] Message-ID: <20231006131452.646721-1-james.clark@arm.com> (raw) Partially revert the change in commit 6148652807ba ("coresight: Enable and disable helper devices adjacent to the path") which changed the bare call from source_ops(csdev)->enable() to coresight_enable_source() for Perf sessions. It was missed that coresight_enable_source() is specifically for the sysfs interface, rather than being a generic call. This interferes with the sysfs reference counting to cause the following crash: $ perf record -e cs_etm/@tmc_etr0/ -C 0 & $ echo 1 > /sys/bus/coresight/devices/tmc_etr0/enable_sink $ echo 1 > /sys/bus/coresight/devices/etm0/enable_source $ echo 0 > /sys/bus/coresight/devices/etm0/enable_source Unable to handle kernel NULL pointer dereference at virtual address 00000000000001d0 Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP ... Call trace: etm4_disable+0x54/0x150 [coresight_etm4x] coresight_disable_source+0x6c/0x98 [coresight] coresight_disable+0x74/0x1c0 [coresight] enable_source_store+0x88/0xa0 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2dc/0x3b0 ksys_write+0x70/0x108 __arm64_sys_write+0x24/0x38 invoke_syscall+0x50/0x128 el0_svc_common.constprop.0+0x104/0x130 do_el0_svc+0x40/0xb8 el0_svc+0x2c/0xb8 el0t_64_sync_handler+0xc0/0xc8 el0t_64_sync+0x1a4/0x1a8 Code: d53cd042 91002000 b9402a81 b8626800 (f940ead5) ---[ end trace 0000000000000000 ]--- This commit linked below also fixes the issue, but has unlocked updates to the mode which could potentially race. So until we come up with a more complete solution that takes all locking and interaction between both modes into account, just revert back to the old behavior for Perf. Reported-by: Junhao He <hejunhao3@huawei.com> Closes: https://lore.kernel.org/linux-arm-kernel/20230921132904.60996-1-hejunhao3@huawei.com/ Fixes: 6148652807ba ("coresight: Enable and disable helper devices adjacent to the path") Signed-off-by: James Clark <james.clark@arm.com> --- drivers/hwtracing/coresight/coresight-etm-perf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 5ca6278baff4..89e8ed214ea4 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -493,7 +493,7 @@ static void etm_event_start(struct perf_event *event, int flags) goto fail_end_stop; /* Finally enable the tracer */ - if (coresight_enable_source(csdev, CS_MODE_PERF, event)) + if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF)) goto fail_disable_path; /* @@ -587,7 +587,7 @@ static void etm_event_stop(struct perf_event *event, int mode) return; /* stop tracer */ - coresight_disable_source(csdev, event); + source_ops(csdev)->disable(csdev, event); /* tell the core */ event->hw.state = PERF_HES_STOPPED; -- 2.34.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2023-10-06 13:15 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-10-06 13:14 James Clark [this message] 2023-10-06 13:14 ` [PATCH] coresight: Fix crash when Perf and sysfs modes are used concurrently James Clark 2023-10-09 12:27 ` Suzuki K Poulose 2023-10-09 12:27 ` Suzuki K Poulose 2023-10-10 2:43 ` hejunhao 2023-10-10 2:43 ` hejunhao 2023-10-16 23:05 ` Suzuki K Poulose 2023-10-16 23:05 ` Suzuki K Poulose
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