diff mbox series

[RFC,V3,4/4] coresight: Have a stab at support for pause / resume

Message ID 20231215064242.36251-1-adrian.hunter@intel.com
State New
Headers
Series None |

Commit Message

Adrian Hunter Dec. 15, 2023, 6:42 a.m. UTC 
  For discussion only, un-tested...

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---


Changes in V3:

	'mode' -> 'flags' so it at least compiles


 .../hwtracing/coresight/coresight-etm-perf.c  | 29 ++++++++++++++++---
 1 file changed, 25 insertions(+), 4 deletions(-)

Comments

James Clark Dec. 20, 2023, 3:59 p.m. UTC | #1 
On 15/12/2023 06:42, Adrian Hunter wrote:
> For discussion only, un-tested...
> 

If anyone wants to test Coresight, the diff below is required to get the
most basic use case working. It also probably needs more thought and
some edge case handling:

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index 596c01e37624..bd0767356277 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -556,7 +556,8 @@ static void etm_event_stop(struct perf_event *event, int mode)
 	struct etm_event_data *event_data;
 	struct list_head *path;
 
-	if (mode & PERF_EF_PAUSE && !READ_ONCE(ctxt->pr_allowed))
+	if ((mode & PERF_EF_PAUSE && !READ_ONCE(ctxt->pr_allowed)) ||
+	    event->hw.state == PERF_HES_STOPPED)
 		return;
 
 	WRITE_ONCE(ctxt->pr_allowed, 0);
@@ -573,9 +574,6 @@ static void etm_event_stop(struct perf_event *event, int mode)
 	/* Clear the event_data as this ETM is stopping the trace. */
 	ctxt->event_data = NULL;
 
-	if (event->hw.state == PERF_HES_STOPPED)
-		goto out_pr_allowed;
-
 	/* We must have a valid event_data for a running event */
 	if (WARN_ON(!event_data))
 		return;
@@ -586,7 +584,7 @@ static void etm_event_stop(struct perf_event *event, int mode)
 	 * nothing needs to be torn down other than outputting a
 	 * zero sized record.
 	 */
-	if (handle->event && (mode & PERF_EF_UPDATE) &&
+	if (handle->event && (mode & (PERF_EF_UPDATE | PERF_EF_PAUSE)) &&
 	    !cpumask_test_cpu(cpu, &event_data->mask)) {
 		event->hw.state = PERF_HES_STOPPED;
 		perf_aux_output_end(handle, 0);
@@ -616,7 +614,7 @@ static void etm_event_stop(struct perf_event *event, int mode)
 	 * handle due to lack of buffer space), we don't
 	 * have to do anything here.
 	 */
-	if (handle->event && (mode & PERF_EF_UPDATE)) {
+	if (handle->event && (mode & (PERF_EF_UPDATE | PERF_EF_PAUSE))) {
 		if (WARN_ON_ONCE(handle->event != event))
 			return;
 
@@ -646,7 +644,6 @@ static void etm_event_stop(struct perf_event *event, int mode)
 	/* Disabling the path make its elements available to other sessions */
 	coresight_disable_path(path);
 
-out_pr_allowed:
 	if (mode & PERF_EF_PAUSE)
 		WRITE_ONCE(ctxt->pr_allowed, 1);
 }
@@ -656,7 +653,7 @@ static int etm_event_add(struct perf_event *event, int mode)
 	int ret = 0;
 	struct hw_perf_event *hwc = &event->hw;
 
-	if (mode & PERF_EF_START && !READ_ONCE(event->aux_paused)) {
+	if (mode & PERF_EF_START) {
 		etm_event_start(event, 0);
 		if (hwc->state & PERF_HES_STOPPED)
 			ret = -EINVAL;
Adrian Hunter Jan. 5, 2024, 12:56 p.m. UTC | #2 
On 20/12/23 17:59, James Clark wrote:
> 
> 
> On 15/12/2023 06:42, Adrian Hunter wrote:
>> For discussion only, un-tested...
>>
> 
> If anyone wants to test Coresight, the diff below is required to get the
> most basic use case working. It also probably needs more thought and
> some edge case handling:

Makes sense to me

> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> index 596c01e37624..bd0767356277 100644
> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> @@ -556,7 +556,8 @@ static void etm_event_stop(struct perf_event *event, int mode)
>  	struct etm_event_data *event_data;
>  	struct list_head *path;
>  
> -	if (mode & PERF_EF_PAUSE && !READ_ONCE(ctxt->pr_allowed))
> +	if ((mode & PERF_EF_PAUSE && !READ_ONCE(ctxt->pr_allowed)) ||
> +	    event->hw.state == PERF_HES_STOPPED)
>  		return;
>  
>  	WRITE_ONCE(ctxt->pr_allowed, 0);
> @@ -573,9 +574,6 @@ static void etm_event_stop(struct perf_event *event, int mode)
>  	/* Clear the event_data as this ETM is stopping the trace. */
>  	ctxt->event_data = NULL;
>  
> -	if (event->hw.state == PERF_HES_STOPPED)
> -		goto out_pr_allowed;
> -
>  	/* We must have a valid event_data for a running event */
>  	if (WARN_ON(!event_data))
>  		return;
> @@ -586,7 +584,7 @@ static void etm_event_stop(struct perf_event *event, int mode)
>  	 * nothing needs to be torn down other than outputting a
>  	 * zero sized record.
>  	 */
> -	if (handle->event && (mode & PERF_EF_UPDATE) &&
> +	if (handle->event && (mode & (PERF_EF_UPDATE | PERF_EF_PAUSE)) &&
>  	    !cpumask_test_cpu(cpu, &event_data->mask)) {
>  		event->hw.state = PERF_HES_STOPPED;
>  		perf_aux_output_end(handle, 0);
> @@ -616,7 +614,7 @@ static void etm_event_stop(struct perf_event *event, int mode)
>  	 * handle due to lack of buffer space), we don't
>  	 * have to do anything here.
>  	 */
> -	if (handle->event && (mode & PERF_EF_UPDATE)) {
> +	if (handle->event && (mode & (PERF_EF_UPDATE | PERF_EF_PAUSE))) {
>  		if (WARN_ON_ONCE(handle->event != event))
>  			return;
>  
> @@ -646,7 +644,6 @@ static void etm_event_stop(struct perf_event *event, int mode)
>  	/* Disabling the path make its elements available to other sessions */
>  	coresight_disable_path(path);
>  
> -out_pr_allowed:
>  	if (mode & PERF_EF_PAUSE)
>  		WRITE_ONCE(ctxt->pr_allowed, 1);
>  }
> @@ -656,7 +653,7 @@ static int etm_event_add(struct perf_event *event, int mode)
>  	int ret = 0;
>  	struct hw_perf_event *hwc = &event->hw;
>  
> -	if (mode & PERF_EF_START && !READ_ONCE(event->aux_paused)) {
> +	if (mode & PERF_EF_START) {
>  		etm_event_start(event, 0);
>  		if (hwc->state & PERF_HES_STOPPED)
>  			ret = -EINVAL;
diff mbox series

Patch

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index 5ca6278baff4..7a69e6417ed4 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -45,6 +45,7 @@  static bool etm_perf_up;
 struct etm_ctxt {
 	struct perf_output_handle handle;
 	struct etm_event_data *event_data;
+	int pr_allowed;
 };
 
 static DEFINE_PER_CPU(struct etm_ctxt, etm_ctxt);
@@ -452,6 +453,13 @@  static void etm_event_start(struct perf_event *event, int flags)
 	struct list_head *path;
 	u64 hw_id;
 
+	if (flags & PERF_EF_RESUME) {
+		if (!READ_ONCE(ctxt->pr_allowed))
+			return;
+	} else if (READ_ONCE(event->aux_paused)) {
+		goto out_pr_allowed;
+	}
+
 	if (!csdev)
 		goto fail;
 
@@ -514,6 +522,8 @@  static void etm_event_start(struct perf_event *event, int flags)
 	event->hw.state = 0;
 	/* Save the event_data for this ETM */
 	ctxt->event_data = event_data;
+out_pr_allowed:
+	WRITE_ONCE(ctxt->pr_allowed, 1);
 	return;
 
 fail_disable_path:
@@ -530,6 +540,7 @@  static void etm_event_start(struct perf_event *event, int flags)
 	}
 fail:
 	event->hw.state = PERF_HES_STOPPED;
+	WRITE_ONCE(ctxt->pr_allowed, 0);
 	return;
 }
 
@@ -543,6 +554,11 @@  static void etm_event_stop(struct perf_event *event, int mode)
 	struct etm_event_data *event_data;
 	struct list_head *path;
 
+	if (mode & PERF_EF_PAUSE && !READ_ONCE(ctxt->pr_allowed))
+		return;
+
+	WRITE_ONCE(ctxt->pr_allowed, 0);
+
 	/*
 	 * If we still have access to the event_data via handle,
 	 * confirm that we haven't messed up the tracking.
@@ -556,7 +572,7 @@  static void etm_event_stop(struct perf_event *event, int mode)
 	ctxt->event_data = NULL;
 
 	if (event->hw.state == PERF_HES_STOPPED)
-		return;
+		goto out_pr_allowed;
 
 	/* We must have a valid event_data for a running event */
 	if (WARN_ON(!event_data))
@@ -627,6 +643,10 @@  static void etm_event_stop(struct perf_event *event, int mode)
 
 	/* Disabling the path make its elements available to other sessions */
 	coresight_disable_path(path);
+
+out_pr_allowed:
+	if (mode & PERF_EF_PAUSE)
+		WRITE_ONCE(ctxt->pr_allowed, 1);
 }
 
 static int etm_event_add(struct perf_event *event, int mode)
@@ -634,7 +654,7 @@  static int etm_event_add(struct perf_event *event, int mode)
 	int ret = 0;
 	struct hw_perf_event *hwc = &event->hw;
 
-	if (mode & PERF_EF_START) {
+	if (mode & PERF_EF_START && !READ_ONCE(event->aux_paused)) {
 		etm_event_start(event, 0);
 		if (hwc->state & PERF_HES_STOPPED)
 			ret = -EINVAL;
@@ -886,8 +906,9 @@  int __init etm_perf_init(void)
 {
 	int ret;
 
-	etm_pmu.capabilities		= (PERF_PMU_CAP_EXCLUSIVE |
-					   PERF_PMU_CAP_ITRACE);
+	etm_pmu.capabilities		= PERF_PMU_CAP_EXCLUSIVE |
+					  PERF_PMU_CAP_ITRACE |
+					  PERF_PMU_CAP_AUX_PAUSE;
 
 	etm_pmu.attr_groups		= etm_pmu_attr_groups;
 	etm_pmu.task_ctx_nr		= perf_sw_context;