From: Leo Yan Date: Fri, 15 May 2026 20:08:16 +0000 (+0100) Subject: coresight: Move per-CPU source pointer to core layer X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=3a4a1c4dd977b5141ad28958d940d2b1aaecf70e;p=thirdparty%2Fkernel%2Flinux.git coresight: Move per-CPU source pointer to core layer Move the per-CPU source pointer from ETM perf to the core layer, as this will be used for not only perf session and also for CPU PM notifiers. Provides coresight_{set|clear|get}_percpu_source() helpers to access the per-CPU source pointer. Add a raw spinlock to protect exclusive access. Device registration and unregistration call the set and clear helpers for init and teardown the pointers. Update callers to invoke coresight_get_percpu_source() for retrieving the pointer. Reviewed-by: Yeoreum Yun Reviewed-by: James Clark Tested-by: James Clark Tested-by: Jie Gan Signed-off-by: Leo Yan Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/20260515-arm_coresight_path_power_management_improvement-v14-9-f88c4a3ecfe9@arm.com --- diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index 6b098c3cab0b..995a4a1bab3d 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -35,6 +35,9 @@ DEFINE_MUTEX(coresight_mutex); static DEFINE_PER_CPU(struct coresight_device *, csdev_sink); +static DEFINE_RAW_SPINLOCK(coresight_dev_lock); +static DEFINE_PER_CPU(struct coresight_device *, csdev_source); + /** * struct coresight_node - elements of a path, from source to sink * @csdev: Address of an element. @@ -82,6 +85,39 @@ struct coresight_device *coresight_get_percpu_sink(int cpu) } EXPORT_SYMBOL_GPL(coresight_get_percpu_sink); +static void coresight_set_percpu_source(struct coresight_device *csdev) +{ + if (!csdev || !coresight_is_percpu_source(csdev)) + return; + + guard(raw_spinlock_irqsave)(&coresight_dev_lock); + + /* Expect no device to be set yet */ + WARN_ON(per_cpu(csdev_source, csdev->cpu)); + per_cpu(csdev_source, csdev->cpu) = csdev; +} + +static void coresight_clear_percpu_source(struct coresight_device *csdev) +{ + if (!csdev || !coresight_is_percpu_source(csdev)) + return; + + guard(raw_spinlock_irqsave)(&coresight_dev_lock); + + /* The per-CPU pointer should contain the same csdev */ + WARN_ON(per_cpu(csdev_source, csdev->cpu) != csdev); + per_cpu(csdev_source, csdev->cpu) = NULL; +} + +struct coresight_device *coresight_get_percpu_source(int cpu) +{ + if (WARN_ON(cpu < 0)) + return NULL; + + guard(raw_spinlock_irqsave)(&coresight_dev_lock); + return per_cpu(csdev_source, cpu); +} + struct coresight_device *coresight_get_source(struct coresight_path *path) { struct coresight_device *csdev; @@ -1452,6 +1488,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) if (ret) goto out_unlock; + coresight_set_percpu_source(csdev); mutex_unlock(&coresight_mutex); if (cti_assoc_ops && cti_assoc_ops->add) @@ -1481,6 +1518,7 @@ void coresight_unregister(struct coresight_device *csdev) cti_assoc_ops->remove(csdev); mutex_lock(&coresight_mutex); + coresight_clear_percpu_source(csdev); etm_perf_del_symlink_sink(csdev); coresight_remove_conns(csdev); coresight_clear_default_sink(csdev); diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index bab85f7dac47..b9e556818c3c 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -49,7 +49,6 @@ struct etm_ctxt { }; static DEFINE_PER_CPU(struct etm_ctxt, etm_ctxt); -static DEFINE_PER_CPU(struct coresight_device *, csdev_src); GEN_PMU_FORMAT_ATTR(cycacc); GEN_PMU_FORMAT_ATTR(timestamp); @@ -386,7 +385,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, struct coresight_path *path; struct coresight_device *csdev; - csdev = per_cpu(csdev_src, cpu); + csdev = coresight_get_percpu_source(cpu); /* * If there is no ETM associated with this CPU clear it from * the mask and continue with the rest. If ever we try to trace @@ -864,17 +863,12 @@ int etm_perf_symlink(struct coresight_device *csdev, bool link) if (!etm_perf_up) return -EPROBE_DEFER; - if (link) { + if (link) ret = sysfs_create_link(&pmu_dev->kobj, &cs_dev->kobj, entry); - if (ret) - return ret; - per_cpu(csdev_src, cpu) = csdev; - } else { + else sysfs_remove_link(&pmu_dev->kobj, entry); - per_cpu(csdev_src, cpu) = NULL; - } - return 0; + return ret; } EXPORT_SYMBOL_GPL(etm_perf_symlink); diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index 75029744561f..4d6f5bc1df9c 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -249,6 +249,7 @@ void coresight_add_helper(struct coresight_device *csdev, void coresight_set_percpu_sink(int cpu, struct coresight_device *csdev); struct coresight_device *coresight_get_percpu_sink(int cpu); struct coresight_device *coresight_get_source(struct coresight_path *path); +struct coresight_device *coresight_get_percpu_source(int cpu); void coresight_disable_source(struct coresight_device *csdev, void *data); void coresight_pause_source(struct coresight_device *csdev); int coresight_resume_source(struct coresight_device *csdev);