From 880af782c6e81cccf507f5a1cf4b23fbb471c39f Mon Sep 17 00:00:00 2001 From: Mathieu Poirier Date: Thu, 25 Apr 2019 13:53:09 -0600 Subject: coresight: tmc-etf: Add support for CPU-wide trace scenarios 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 Tested-by: Leo Yan Tested-by: Robert Walker Signed-off-by: Greg Kroah-Hartman --- drivers/hwtracing/coresight/coresight-tmc-etf.c | 40 +++++++++++++++++++++---- 1 file changed, 35 insertions(+), 5 deletions(-) (limited to 'drivers/hwtracing') diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index 1df1f8fade71..2527b5d3b65e 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -223,6 +223,7 @@ out: static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data) { int ret = 0; + pid_t pid; unsigned long flags; struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); 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) break; /* - * In Perf mode there can be only one writer per sink. There - * is also no need to continue if the ETB/ETF is already - * operated from sysFS. + * No need to continue if the ETB/ETF is already operated + * from sysFS. */ - if (drvdata->mode != CS_MODE_DISABLED) + if (drvdata->mode == CS_MODE_SYSFS) { + ret = -EBUSY; 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); if (ret) 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); if (!ret) { + /* Associate with monitored process. */ + drvdata->pid = pid; drvdata->mode = CS_MODE_PERF; 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 */ WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED); tmc_etb_disable_hw(drvdata); + /* Dissociate from monitored process. */ + drvdata->pid = -1; drvdata->mode = CS_MODE_DISABLED; spin_unlock_irqrestore(&drvdata->spinlock, flags); @@ -414,7 +438,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev, u32 *buf_ptr; u64 read_ptr, write_ptr; u32 status; - unsigned long offset, to_read, flags; + unsigned long offset, to_read = 0, flags; struct cs_buffers *buf = sink_config; 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; 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); 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; } CS_LOCK(drvdata->base); +out: spin_unlock_irqrestore(&drvdata->spinlock, flags); return to_read; -- cgit v1.2.3