Hi Yabin,
Sorry for late reply as I was on vacation for the past two weeks.
On Tue, Apr 15, 2025 at 11:46:48AM -0700, Yabin Cui wrote:
When tracing ETM data on multiple CPUs concurrently via the perf interface, the CATU device is shared across different CPU paths. This can lead to race conditions when multiple CPUs attempt to enable or disable the CATU device simultaneously.
To address these race conditions, this patch introduces the following changes:
The enable and disable operations for the CATU device are not reentrant. Therefore, a spinlock is added to ensure that only one CPU can enable or disable a given CATU device at any point in time.
A reference counter is used to manage the enable/disable state of the CATU device. The device is enabled when the first CPU requires it and is only disabled when the last CPU finishes using it. This ensures the device remains active as long as at least one CPU needs it.
Signed-off-by: Yabin Cui yabinc@google.com
LGTM:
Reviewed-by: Leo Yan leo.yan@arm.com
As Jie reminded, please add James' review tag in next spin.
Thanks, Leo
drivers/hwtracing/coresight/coresight-catu.c | 25 +++++++++++++------- drivers/hwtracing/coresight/coresight-catu.h | 1 + 2 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-catu.c b/drivers/hwtracing/coresight/coresight-catu.c index fa170c966bc3..3909b562b077 100644 --- a/drivers/hwtracing/coresight/coresight-catu.c +++ b/drivers/hwtracing/coresight/coresight-catu.c @@ -458,12 +458,17 @@ static int catu_enable_hw(struct catu_drvdata *drvdata, enum cs_mode cs_mode, static int catu_enable(struct coresight_device *csdev, enum cs_mode mode, void *data) {
- int rc;
- int rc = 0; struct catu_drvdata *catu_drvdata = csdev_to_catu_drvdata(csdev);
- CS_UNLOCK(catu_drvdata->base);
- rc = catu_enable_hw(catu_drvdata, mode, data);
- CS_LOCK(catu_drvdata->base);
- guard(raw_spinlock_irqsave)(&catu_drvdata->spinlock);
- if (csdev->refcnt == 0) {
CS_UNLOCK(catu_drvdata->base);rc = catu_enable_hw(catu_drvdata, mode, data);CS_LOCK(catu_drvdata->base);- }
- if (!rc)
csdev->refcnt++;} @@ -486,12 +491,15 @@ static int catu_disable_hw(struct catu_drvdata *drvdata) static int catu_disable(struct coresight_device *csdev, void *__unused) {
- int rc;
- int rc = 0; struct catu_drvdata *catu_drvdata = csdev_to_catu_drvdata(csdev);
- CS_UNLOCK(catu_drvdata->base);
- rc = catu_disable_hw(catu_drvdata);
- CS_LOCK(catu_drvdata->base);
- guard(raw_spinlock_irqsave)(&catu_drvdata->spinlock);
- if (--csdev->refcnt == 0) {
CS_UNLOCK(catu_drvdata->base);rc = catu_disable_hw(catu_drvdata);CS_LOCK(catu_drvdata->base);- } return rc;
} @@ -550,6 +558,7 @@ static int __catu_probe(struct device *dev, struct resource *res) dev->platform_data = pdata; drvdata->base = base;
- raw_spin_lock_init(&drvdata->spinlock); catu_desc.access = CSDEV_ACCESS_IOMEM(base); catu_desc.pdata = pdata; catu_desc.dev = dev;
diff --git a/drivers/hwtracing/coresight/coresight-catu.h b/drivers/hwtracing/coresight/coresight-catu.h index 141feac1c14b..755776cd19c5 100644 --- a/drivers/hwtracing/coresight/coresight-catu.h +++ b/drivers/hwtracing/coresight/coresight-catu.h @@ -65,6 +65,7 @@ struct catu_drvdata { void __iomem *base; struct coresight_device *csdev; int irq;
- raw_spinlock_t spinlock;
};
#define CATU_REG32(name, offset) \
2.49.0.604.gff1f9ca942-goog