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coresight: tmc-etf: Add support for CPU-wide trace scenarios

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This patch adds support for CPU-wide trace scenarios by making sure that
only the sources monitoring the same process have access to a common sink.
Because the sink is shared between sources, the first source to use the
sink switches it on while the last one does the cleanup.  Any attempt to
modify the HW is overlooked for as long as more than one source is using
a sink.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Robert Walker <robert.walker@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mathieu Poirier 2019-04-25 13:53:09 -06:00 committed by Greg Kroah-Hartman
parent 8d03cfd16a
commit 880af782c6
1 changed files with 35 additions and 5 deletions
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40
drivers/hwtracing/coresight/coresight-tmc-etf.c
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@ -223,6 +223,7 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data) static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data)
{ {
int ret = 0; int ret = 0;
pid_t pid;
unsigned long flags; unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
struct perf_output_handle *handle = data; struct perf_output_handle *handle = data;
@ -233,18 +234,39 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data)
if (drvdata->reading) if (drvdata->reading)
break; break;
/* /*
* In Perf mode there can be only one writer per sink. There * No need to continue if the ETB/ETF is already operated
* is also no need to continue if the ETB/ETF is already * from sysFS.
* operated from sysFS.
*/ */
if (drvdata->mode != CS_MODE_DISABLED) if (drvdata->mode == CS_MODE_SYSFS) {
ret = -EBUSY;
break; break;
}
/* Get a handle on the pid of the process to monitor */
pid = task_pid_nr(handle->event->owner);
if (drvdata->pid != -1 && drvdata->pid != pid) {
ret = -EBUSY;
break;
}
ret = tmc_set_etf_buffer(csdev, handle); ret = tmc_set_etf_buffer(csdev, handle);
if (ret) if (ret)
break; break;
/*
* No HW configuration is needed if the sink is already in
* use for this session.
*/
if (drvdata->pid == pid) {
atomic_inc(csdev->refcnt);
break;
}
ret = tmc_etb_enable_hw(drvdata); ret = tmc_etb_enable_hw(drvdata);
if (!ret) { if (!ret) {
/* Associate with monitored process. */
drvdata->pid = pid;
drvdata->mode = CS_MODE_PERF; drvdata->mode = CS_MODE_PERF;
atomic_inc(csdev->refcnt); atomic_inc(csdev->refcnt);
} }
@ -300,6 +322,8 @@ static int tmc_disable_etf_sink(struct coresight_device *csdev)
/* Complain if we (somehow) got out of sync */ /* Complain if we (somehow) got out of sync */
WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED); WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED);
tmc_etb_disable_hw(drvdata); tmc_etb_disable_hw(drvdata);
/* Dissociate from monitored process. */
drvdata->pid = -1;
drvdata->mode = CS_MODE_DISABLED; drvdata->mode = CS_MODE_DISABLED;
spin_unlock_irqrestore(&drvdata->spinlock, flags); spin_unlock_irqrestore(&drvdata->spinlock, flags);
@ -414,7 +438,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
u32 *buf_ptr; u32 *buf_ptr;
u64 read_ptr, write_ptr; u64 read_ptr, write_ptr;
u32 status; u32 status;
unsigned long offset, to_read, flags; unsigned long offset, to_read = 0, flags;
struct cs_buffers *buf = sink_config; struct cs_buffers *buf = sink_config;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
@ -426,6 +450,11 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
return 0; return 0;
spin_lock_irqsave(&drvdata->spinlock, flags); spin_lock_irqsave(&drvdata->spinlock, flags);
/* Don't do anything if another tracer is using this sink */
if (atomic_read(csdev->refcnt) != 1)
goto out;
CS_UNLOCK(drvdata->base); CS_UNLOCK(drvdata->base);
tmc_flush_and_stop(drvdata); tmc_flush_and_stop(drvdata);
@ -519,6 +548,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
to_read = buf->nr_pages << PAGE_SHIFT; to_read = buf->nr_pages << PAGE_SHIFT;
} }
CS_LOCK(drvdata->base); CS_LOCK(drvdata->base);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags); spin_unlock_irqrestore(&drvdata->spinlock, flags);
return to_read; return to_read;