Re: [PATCH v2 18/23] coresight: trbe: Keep the perf handle in per-CPU data

[James Clark <james.clark@linaro.org>]

On 16/10/2026 17:55, Leo Yan wrote:
> Arm SPE owns a per-CPU perf output handle for the PMU lifetime. TRBE
> instead receives a handle from CoreSight when enabling its sink.
> 
> Store that session handle in trbe_cpudata instead of a separate per-CPU
> pointer array, and pass the CPU data as the per-CPU IRQ context. Use this
> context directly for overflow and spurious interrupt handling so local
> hardware control does not depend on the current AUX buffer configuration.
> 
> Allocate the CPU data before registering the IRQ and free it after
> releasing the IRQ, keeping the IRQ context valid throughout registration.
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> ---
>   drivers/hwtracing/coresight/coresight-trbe.c | 44 ++++++++++++----------------
>   1 file changed, 19 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index 9a469c8009ce8a8a8b804c2b63a68e741f1dceaa..2328aab0a084a0ac123e950f846f404d120ec2c0 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -139,6 +139,7 @@ struct trbe_save_state {
>    * @cpu			- CPU this TRBE belongs to.
>    * @mode		- Mode of current operation. (perf/disabled)
>    * @buf			- Buffer configuration retained for the enabled session.
> + * @handle		- Perf output handle from successful enable until disable.
>    * @drvdata		- TRBE specific drvdata
>    * @errata		- Bit map for the errata on this TRBE.
>    */
> @@ -149,6 +150,7 @@ struct trbe_cpudata {
>   	int cpu;
>   	enum cs_mode mode;
>   	struct trbe_buf *buf;
> +	struct perf_output_handle *handle;
>   	struct trbe_drvdata *drvdata;
>   	struct trbe_save_state save_state;
>   	DECLARE_BITMAP(errata, TRBE_ERRATA_MAX);
> @@ -156,7 +158,6 @@ struct trbe_cpudata {
>   
>   struct trbe_drvdata {
>   	struct trbe_cpudata __percpu *cpudata;
> -	struct perf_output_handle * __percpu *handle;
>   	struct hlist_node hotplug_node;
>   	int irq;
>   	cpumask_t supported_cpus;
> @@ -1091,7 +1092,7 @@ static int arm_trbe_enable(struct coresight_device *csdev, enum cs_mode mode,
>   		return ret;
>   	}
>   
> -	*this_cpu_ptr(drvdata->handle) = handle;
> +	cpudata->handle = handle;
>   	cpudata->buf = buf;
>   	cpudata->mode = mode;
>   	return 0;
> @@ -1112,16 +1113,15 @@ static int arm_trbe_disable(struct coresight_device *csdev)
>   	trbe_drain_and_disable_local(cpudata);
>   	clr_trbe_status();
>   
> -	*this_cpu_ptr(drvdata->handle) = NULL;
>   	buf->cpudata = NULL;
> +	cpudata->handle = NULL;
>   	cpudata->buf = NULL;
>   	cpudata->mode = CS_MODE_DISABLED;
>   	return 0;
>   }
>   
> -static void trbe_handle_spurious(struct perf_output_handle *handle)
> +static void trbe_handle_spurious(struct trbe_cpudata *cpudata)
>   {
> -	struct trbe_buf *buf = etm_perf_sink_config(handle);
>   	u64 trblimitr = read_sysreg_s(SYS_TRBLIMITR_EL1);
>   
>   	/*
> @@ -1129,11 +1129,12 @@ static void trbe_handle_spurious(struct perf_output_handle *handle)
>   	 * back without modifying the buffer parameters to
>   	 * retain the trace collected so far.
>   	 */
> -	set_trbe_enabled(buf->cpudata, trblimitr);
> +	set_trbe_enabled(cpudata, trblimitr);
>   }
>   
> -static int trbe_handle_overflow(struct perf_output_handle *handle)
> +static int trbe_handle_overflow(struct trbe_cpudata *cpudata)
>   {
> +	struct perf_output_handle *handle = cpudata->handle;
>   	struct perf_event *event = handle->event;
>   	struct trbe_buf *buf = etm_perf_sink_config(handle);
>   	unsigned long size;
> @@ -1203,9 +1204,8 @@ static u64 cpu_prohibit_trace(void)
>   
>   static irqreturn_t arm_trbe_irq_handler(int irq, void *dev)
>   {
> -	struct perf_output_handle **handle_ptr = dev;
> -	struct perf_output_handle *handle = *handle_ptr;
> -	struct trbe_buf *buf;
> +	struct trbe_cpudata *cpudata = dev;
> +	struct perf_output_handle *handle = cpudata->handle;
>   	enum trbe_fault_action act;
>   	u64 status;
>   	bool truncated = false;
> @@ -1232,18 +1232,17 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev)
>   	 * Ensure the trace is visible to the CPUs and
>   	 * any external aborts have been resolved.
>   	 */
> -	buf = etm_perf_sink_config(handle);
> -	trbe_drain_and_disable_local(buf->cpudata);
> +	trbe_drain_and_disable_local(cpudata);
>   	clr_trbe_irq();
>   	isb();
>   
>   	act = trbe_get_fault_act(handle, status);
>   	switch (act) {
>   	case TRBE_FAULT_ACT_WRAP:
> -		truncated = !!trbe_handle_overflow(handle);
> +		truncated = !!trbe_handle_overflow(cpudata);
>   		break;
>   	case TRBE_FAULT_ACT_SPURIOUS:
> -		trbe_handle_spurious(handle);
> +		trbe_handle_spurious(cpudata);
>   		break;
>   	case TRBE_FAULT_ACT_FATAL:
>   		trbe_truncate_event(handle);
> @@ -1507,10 +1506,6 @@ static int arm_trbe_probe_coresight(struct trbe_drvdata *drvdata)
>   {
>   	int cpu;
>   
> -	drvdata->cpudata = alloc_percpu(typeof(*drvdata->cpudata));
> -	if (!drvdata->cpudata)
> -		return -ENOMEM;
> -
>   	for_each_cpu(cpu, &drvdata->supported_cpus) {
>   		/* If we fail to probe the CPU, let us defer it to hotplug callbacks */
>   		if (smp_call_function_single(cpu, arm_trbe_probe_cpu, drvdata, 1))
> @@ -1531,7 +1526,6 @@ static int arm_trbe_remove_coresight(struct trbe_drvdata *drvdata)
>   		smp_call_function_single(cpu, arm_trbe_disable_cpu, drvdata, 1);
>   		arm_trbe_remove_coresight_cpu(drvdata, cpu);
>   	}
> -	free_percpu(drvdata->cpudata);
>   	return 0;
>   }
>   
> @@ -1618,14 +1612,14 @@ static int arm_trbe_probe_irq(struct platform_device *pdev,
>   
>   	cpumask_copy(&drvdata->supported_cpus, affinity);
>   
> -	drvdata->handle = alloc_percpu(struct perf_output_handle *);
> -	if (!drvdata->handle)
> +	drvdata->cpudata = alloc_percpu(typeof(*drvdata->cpudata));
> +	if (!drvdata->cpudata)
>   		return -ENOMEM;
>   
>   	ret = request_percpu_irq_affinity(drvdata->irq, arm_trbe_irq_handler, DRVNAME,
> -					  affinity, drvdata->handle);
> +					  affinity, drvdata->cpudata);
>   	if (ret) {
> -		free_percpu(drvdata->handle);
> +		free_percpu(drvdata->cpudata);
>   		return ret;
>   	}
>   	return 0;
> @@ -1633,8 +1627,8 @@ static int arm_trbe_probe_irq(struct platform_device *pdev,
>   
>   static void arm_trbe_remove_irq(struct trbe_drvdata *drvdata)
>   {
> -	free_percpu_irq(drvdata->irq, drvdata->handle);
> -	free_percpu(drvdata->handle);
> +	free_percpu_irq(drvdata->irq, drvdata->cpudata);
> +	free_percpu(drvdata->cpudata);
>   }
>   
>   static int arm_trbe_device_probe(struct platform_device *pdev)
> 
Reviewed-by: James Clark <james.clark@linaro.org>