diff options
| author | James Clark <james.clark@arm.com> | 2023-10-06 14:14:52 +0100 |
|---|---|---|
| committer | Suzuki K Poulose <suzuki.poulose@arm.com> | 2023-11-13 09:40:28 +0000 |
| commit | 287e82cf69aa264a52bc37591bd0eb407e20f85c (patch) | |
| tree | 4510eb95b8aac8e4309aed20e092717d4d1a7d7f /drivers/hwtracing | |
| parent | 348ddab81f7b0983d9fb158df910254f08d3f887 (diff) | |
| download | linux-287e82cf69aa264a52bc37591bd0eb407e20f85c.tar.gz | |
coresight: Fix crash when Perf and sysfs modes are used concurrently
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")
Tested-by: Junhao He <hejunhao3@huawei.com>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20231006131452.646721-1-james.clark@arm.com
Diffstat (limited to 'drivers/hwtracing')
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-etm-perf.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 5ca6278baff4fa..89e8ed214ea496 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; |