[v4,4/6] coresight: tmc: Hook callback for panic kdump

Message ID 1522379724-30648-5-git-send-email-leo.yan@linaro.org
State New
Headers show
Series
  • Coresight: Support panic kdump
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Commit Message

Leo Yan March 30, 2018, 3:15 a.m.
Since Coresight panic kdump functionality has been ready, this patch is
to hook panic callback function for ETB/ETF driver.  The driver data
structure has allocated a buffer when the session started, so simply
save tracing data into this buffer when panic happens and update buffer
related info for kdump.

Signed-off-by: Leo Yan <leo.yan@linaro.org>

---
 drivers/hwtracing/coresight/coresight-tmc-etf.c | 30 +++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

-- 
2.7.4

Comments

Mathieu Poirier April 2, 2018, 8:36 p.m. | #1
On Fri, Mar 30, 2018 at 11:15:22AM +0800, Leo Yan wrote:
> Since Coresight panic kdump functionality has been ready, this patch is

> to hook panic callback function for ETB/ETF driver.  The driver data

> structure has allocated a buffer when the session started, so simply

> save tracing data into this buffer when panic happens and update buffer

> related info for kdump.

> 

> Signed-off-by: Leo Yan <leo.yan@linaro.org>

> ---

>  drivers/hwtracing/coresight/coresight-tmc-etf.c | 30 +++++++++++++++++++++++++

>  1 file changed, 30 insertions(+)

> 

> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c

> index e2513b7..d20d546 100644

> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c

> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c

> @@ -504,6 +504,35 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev,

>  	CS_LOCK(drvdata->base);

>  }

>  

> +static void tmc_panic_cb(void *data)


I would call the function tmc_kdump_panic_cb()... That way there is absolutely
no confusion as to what it does.

> +{

> +	struct coresight_device *csdev = (struct coresight_device *)data;

> +	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

> +	unsigned long flags;

> +

> +	if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETB &&

> +			 drvdata->config_type != TMC_CONFIG_TYPE_ETF))

> +		return;

> +

> +	if (drvdata->mode == CS_MODE_DISABLED)

> +		return;


This is racy - between the check and acquiring the spinlock someone may beat you
to it.

> +

> +	spin_lock_irqsave(&drvdata->spinlock, flags);


        if (drvdata->mode == CS_MODE_DISABLED)
                goto out;

        drvdata->mode = CS_MODE_DISABLED

> +

> +	CS_UNLOCK(drvdata->base);

> +

> +	tmc_flush_and_stop(drvdata);

> +	tmc_etb_dump_hw(drvdata);

> +

> +	CS_LOCK(drvdata->base);

> +

> +	/* Update buffer info for panic dump */

> +	csdev->kdump_buf = drvdata->buf;

> +	csdev->kdump_buf_sz = drvdata->len;


out:
> +

> +	spin_unlock_irqrestore(&drvdata->spinlock, flags);

> +}

> +

>  static const struct coresight_ops_sink tmc_etf_sink_ops = {

>  	.enable		= tmc_enable_etf_sink,

>  	.disable	= tmc_disable_etf_sink,

> @@ -512,6 +541,7 @@ static const struct coresight_ops_sink tmc_etf_sink_ops = {

>  	.set_buffer	= tmc_set_etf_buffer,

>  	.reset_buffer	= tmc_reset_etf_buffer,

>  	.update_buffer	= tmc_update_etf_buffer,

> +	.panic_cb	= tmc_panic_cb,

>  };

>  

>  static const struct coresight_ops_link tmc_etf_link_ops = {

> -- 

> 2.7.4

>

Patch

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index e2513b7..d20d546 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -504,6 +504,35 @@  static void tmc_update_etf_buffer(struct coresight_device *csdev,
 	CS_LOCK(drvdata->base);
 }
 
+static void tmc_panic_cb(void *data)
+{
+	struct coresight_device *csdev = (struct coresight_device *)data;
+	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+	unsigned long flags;
+
+	if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
+			 drvdata->config_type != TMC_CONFIG_TYPE_ETF))
+		return;
+
+	if (drvdata->mode == CS_MODE_DISABLED)
+		return;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	CS_UNLOCK(drvdata->base);
+
+	tmc_flush_and_stop(drvdata);
+	tmc_etb_dump_hw(drvdata);
+
+	CS_LOCK(drvdata->base);
+
+	/* Update buffer info for panic dump */
+	csdev->kdump_buf = drvdata->buf;
+	csdev->kdump_buf_sz = drvdata->len;
+
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+}
+
 static const struct coresight_ops_sink tmc_etf_sink_ops = {
 	.enable		= tmc_enable_etf_sink,
 	.disable	= tmc_disable_etf_sink,
@@ -512,6 +541,7 @@  static const struct coresight_ops_sink tmc_etf_sink_ops = {
 	.set_buffer	= tmc_set_etf_buffer,
 	.reset_buffer	= tmc_reset_etf_buffer,
 	.update_buffer	= tmc_update_etf_buffer,
+	.panic_cb	= tmc_panic_cb,
 };
 
 static const struct coresight_ops_link tmc_etf_link_ops = {