From 2956315ed53bf43495c2d9cddc07c38474b5874c Mon Sep 17 00:00:00 2001 From: Yabin Cui Date: Tue, 29 Apr 2025 16:12:59 -0700 Subject: [PATCH] BACKPORT: FROMGIT: coresight: catu: Introduce refcount and spinlock for enabling/disabling 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: 1. 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. 2. 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. Bug: 393467632 (cherry picked from commit a03a0a08c6fe5e50c1b12ea41b9e228e7f649c22 https: //git.kernel.org/pub/scm/linux/kernel/git/coresight/linux.git next) Fixes: fcacb5c154ba ("coresight: Introduce support for Coresight Address Translation Unit") Change-Id: Idf0f1cbb863c3acd4ac61d071f5c57cbcb16a160 Signed-off-by: Yabin Cui Reviewed-by: James Clark Reviewed-by: Leo Yan Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/20250429231301.1952246-2-yabinc@google.com --- 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 c062bcc09466..f3f591e261ab 100644 --- a/drivers/hwtracing/coresight/coresight-catu.c +++ b/drivers/hwtracing/coresight/coresight-catu.c @@ -456,12 +456,17 @@ 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 (atomic_read(&csdev->refcnt) == 0) { + CS_UNLOCK(catu_drvdata->base); + rc = catu_enable_hw(catu_drvdata, mode, data); + CS_LOCK(catu_drvdata->base); + } + if (!rc) + atomic_inc(&csdev->refcnt); return rc; } @@ -484,12 +489,15 @@ 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 (atomic_dec_return(&csdev->refcnt) == 0) { + CS_UNLOCK(catu_drvdata->base); + rc = catu_disable_hw(catu_drvdata); + CS_LOCK(catu_drvdata->base); + } return rc; } @@ -556,6 +564,7 @@ static int catu_probe(struct amba_device *adev, const struct amba_id *id) 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 442e034bbfba..577b65ed8f7f 100644 --- a/drivers/hwtracing/coresight/coresight-catu.h +++ b/drivers/hwtracing/coresight/coresight-catu.h @@ -64,6 +64,7 @@ struct catu_drvdata { void __iomem *base; struct coresight_device *csdev; int irq; + raw_spinlock_t spinlock; }; #define CATU_REG32(name, offset) \