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@hu... 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;
Junhao He,
Please could you test the patch and let us know if it resolves the problem for you ?
On 06/10/2023 14:14, James Clark wrote:
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@hu... Fixes: 6148652807ba ("coresight: Enable and disable helper devices adjacent to the path") Signed-off-by: James Clark james.clark@arm.com
The patch looks good to me. I will wait for Junhao to test this before pulling it in.
Suzuki
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;
On 2023/10/9 20:27, Suzuki K Poulose wrote:
Junhao He,
Please could you test the patch and let us know if it resolves the problem for you ?
Hi James and Suzuki ,
I tested the patch on my platform and it worked well.
On 06/10/2023 14:14, James Clark wrote:
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@hu... Fixes: 6148652807ba ("coresight: Enable and disable helper devices adjacent to the path") Signed-off-by: James Clark james.clark@arm.com
The patch looks good to me. I will wait for Junhao to test this before pulling it in.
Suzuki
Tested-by: Junhao He hejunhao3@huawei.com
Thanks. Junhao.
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;
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.
On Fri, 6 Oct 2023 14:14:52 +0100, James Clark wrote:
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:
[...]
Applied, thanks!
[1/1] coresight: Fix crash when Perf and sysfs modes are used concurrently https://git.kernel.org/coresight/c/078dbba3f0c9
Best regards,
-
hejunhao -
James Clark -
Suzuki K Poulose