[PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

[PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

[Kuan-Wei Chiu]

The cntr_val_show() function was intended to print the values of all
counters using a loop. However, due to a buffer overwrite issue with
sprintf(), it effectively only displayed the value of the last counter.

The companion function, cntr_val_store(), allows users to modify a
specific counter selected by 'cntr_idx'. To maintain consistency
between read and write operations and to align with the ETM4x driver
behavior, modify cntr_val_show() to report only the value of the
currently selected counter.

This change removes the loop and the "counter %d:" prefix, printing
only the hexadecimal value. It also adopts sysfs_emit() for standard
sysfs output formatting.

Fixes: a939fc5a71ad ("coresight-etm: add CoreSight ETM/PTM driver")
Cc: stable@vger.kernel.org
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
Build test only.

Changes in v3:
- Switch format specifier to %#x to include the 0x prefix.
- Add Cc stable

v2: https://lore.kernel.org/lkml/20251201095228.1905489-1-visitorckw@gmail.com/

 .../hwtracing/coresight/coresight-etm3x-sysfs.c   | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
index 762109307b86..b3c67e96a82a 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
@@ -717,26 +717,19 @@ static DEVICE_ATTR_RW(cntr_rld_event);
 static ssize_t cntr_val_show(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
-	int i, ret = 0;
 	u32 val;
 	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
 	struct etm_config *config = &drvdata->config;
 
 	if (!coresight_get_mode(drvdata->csdev)) {
 		spin_lock(&drvdata->spinlock);
-		for (i = 0; i < drvdata->nr_cntr; i++)
-			ret += sprintf(buf, "counter %d: %x\n",
-				       i, config->cntr_val[i]);
+		val = config->cntr_val[config->cntr_idx];
 		spin_unlock(&drvdata->spinlock);
-		return ret;
-	}
-
-	for (i = 0; i < drvdata->nr_cntr; i++) {
-		val = etm_readl(drvdata, ETMCNTVRn(i));
-		ret += sprintf(buf, "counter %d: %x\n", i, val);
+	} else {
+		val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx));
 	}
 
-	return ret;
+	return sysfs_emit(buf, "%#x\n", val);
 }
 
 static ssize_t cntr_val_store(struct device *dev,
-- 
2.52.0.158.g65b55ccf14-goog

Re: [PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

[James Clark]

On 02/12/2025 8:26 am, Kuan-Wei Chiu wrote:
> The cntr_val_show() function was intended to print the values of all
> counters using a loop. However, due to a buffer overwrite issue with
> sprintf(), it effectively only displayed the value of the last counter.
> 
> The companion function, cntr_val_store(), allows users to modify a
> specific counter selected by 'cntr_idx'. To maintain consistency
> between read and write operations and to align with the ETM4x driver
> behavior, modify cntr_val_show() to report only the value of the
> currently selected counter.
> 
> This change removes the loop and the "counter %d:" prefix, printing
> only the hexadecimal value. It also adopts sysfs_emit() for standard
> sysfs output formatting.
> 
> Fixes: a939fc5a71ad ("coresight-etm: add CoreSight ETM/PTM driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> ---
> Build test only.
> 
> Changes in v3:
> - Switch format specifier to %#x to include the 0x prefix.
> - Add Cc stable
> 
> v2: https://lore.kernel.org/lkml/20251201095228.1905489-1-visitorckw@gmail.com/
> 
>   .../hwtracing/coresight/coresight-etm3x-sysfs.c   | 15 ++++-----------
>   1 file changed, 4 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> index 762109307b86..b3c67e96a82a 100644
> --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> @@ -717,26 +717,19 @@ static DEVICE_ATTR_RW(cntr_rld_event);
>   static ssize_t cntr_val_show(struct device *dev,
>   			     struct device_attribute *attr, char *buf)
>   {
> -	int i, ret = 0;
>   	u32 val;
>   	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
>   	struct etm_config *config = &drvdata->config;
>   
>   	if (!coresight_get_mode(drvdata->csdev)) {
>   		spin_lock(&drvdata->spinlock);
> -		for (i = 0; i < drvdata->nr_cntr; i++)
> -			ret += sprintf(buf, "counter %d: %x\n",
> -				       i, config->cntr_val[i]);
> +		val = config->cntr_val[config->cntr_idx];
>   		spin_unlock(&drvdata->spinlock);
> -		return ret;
> -	}
> -
> -	for (i = 0; i < drvdata->nr_cntr; i++) {
> -		val = etm_readl(drvdata, ETMCNTVRn(i));
> -		ret += sprintf(buf, "counter %d: %x\n", i, val);
> +	} else {
> +		val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx));
>   	}
>   
> -	return ret;
> +	return sysfs_emit(buf, "%#x\n", val);
>   }
>   
>   static ssize_t cntr_val_store(struct device *dev,

Reviewed-by: James Clark <james.clark@linaro.org>

Re: [PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

[Kuan-Wei Chiu]

On Tue, Dec 02, 2025 at 09:26:19AM +0000, James Clark wrote:
> 
> 
> On 02/12/2025 8:26 am, Kuan-Wei Chiu wrote:
> > The cntr_val_show() function was intended to print the values of all
> > counters using a loop. However, due to a buffer overwrite issue with
> > sprintf(), it effectively only displayed the value of the last counter.
> > 
> > The companion function, cntr_val_store(), allows users to modify a
> > specific counter selected by 'cntr_idx'. To maintain consistency
> > between read and write operations and to align with the ETM4x driver
> > behavior, modify cntr_val_show() to report only the value of the
> > currently selected counter.
> > 
> > This change removes the loop and the "counter %d:" prefix, printing
> > only the hexadecimal value. It also adopts sysfs_emit() for standard
> > sysfs output formatting.
> > 
> > Fixes: a939fc5a71ad ("coresight-etm: add CoreSight ETM/PTM driver")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > ---
> > Build test only.
> > 
> > Changes in v3:
> > - Switch format specifier to %#x to include the 0x prefix.
> > - Add Cc stable
> > 
> > v2: https://lore.kernel.org/lkml/20251201095228.1905489-1-visitorckw@gmail.com/
> > 
> >   .../hwtracing/coresight/coresight-etm3x-sysfs.c   | 15 ++++-----------
> >   1 file changed, 4 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > index 762109307b86..b3c67e96a82a 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > @@ -717,26 +717,19 @@ static DEVICE_ATTR_RW(cntr_rld_event);
> >   static ssize_t cntr_val_show(struct device *dev,
> >   			     struct device_attribute *attr, char *buf)
> >   {
> > -	int i, ret = 0;
> >   	u32 val;
> >   	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> >   	struct etm_config *config = &drvdata->config;
> >   	if (!coresight_get_mode(drvdata->csdev)) {
> >   		spin_lock(&drvdata->spinlock);
> > -		for (i = 0; i < drvdata->nr_cntr; i++)
> > -			ret += sprintf(buf, "counter %d: %x\n",
> > -				       i, config->cntr_val[i]);
> > +		val = config->cntr_val[config->cntr_idx];
> >   		spin_unlock(&drvdata->spinlock);
> > -		return ret;
> > -	}
> > -
> > -	for (i = 0; i < drvdata->nr_cntr; i++) {
> > -		val = etm_readl(drvdata, ETMCNTVRn(i));
> > -		ret += sprintf(buf, "counter %d: %x\n", i, val);
> > +	} else {
> > +		val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx));
> >   	}
> > -	return ret;
> > +	return sysfs_emit(buf, "%#x\n", val);
> >   }
> >   static ssize_t cntr_val_store(struct device *dev,
> 
> Reviewed-by: James Clark <james.clark@linaro.org>
> 
Thanks for the review!
Is there anything else I need to do for this fix to land?

Regards,
Kuan-Wei

Re: [PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

[Suzuki K Poulose]

Hello

On 02/02/2026 05:09, Kuan-Wei Chiu wrote:
> On Tue, Dec 02, 2025 at 09:26:19AM +0000, James Clark wrote:
>>
>>
>> On 02/12/2025 8:26 am, Kuan-Wei Chiu wrote:
>>> The cntr_val_show() function was intended to print the values of all
>>> counters using a loop. However, due to a buffer overwrite issue with
>>> sprintf(), it effectively only displayed the value of the last counter.
>>>
>>> The companion function, cntr_val_store(), allows users to modify a
>>> specific counter selected by 'cntr_idx'. To maintain consistency
>>> between read and write operations and to align with the ETM4x driver
>>> behavior, modify cntr_val_show() to report only the value of the
>>> currently selected counter.
>>>
>>> This change removes the loop and the "counter %d:" prefix, printing
>>> only the hexadecimal value. It also adopts sysfs_emit() for standard
>>> sysfs output formatting.
>>>
>>> Fixes: a939fc5a71ad ("coresight-etm: add CoreSight ETM/PTM driver")
>>> Cc: stable@vger.kernel.org
>>> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
>>> ---
>>> Build test only.
>>>
>>> Changes in v3:
>>> - Switch format specifier to %#x to include the 0x prefix.
>>> - Add Cc stable
>>>
>>> v2: https://lore.kernel.org/lkml/20251201095228.1905489-1-visitorckw@gmail.com/
>>>
>>>    .../hwtracing/coresight/coresight-etm3x-sysfs.c   | 15 ++++-----------
>>>    1 file changed, 4 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>>> index 762109307b86..b3c67e96a82a 100644
>>> --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>>> +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>>> @@ -717,26 +717,19 @@ static DEVICE_ATTR_RW(cntr_rld_event);
>>>    static ssize_t cntr_val_show(struct device *dev,
>>>    			     struct device_attribute *attr, char *buf)
>>>    {
>>> -	int i, ret = 0;
>>>    	u32 val;
>>>    	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
>>>    	struct etm_config *config = &drvdata->config;
>>>    	if (!coresight_get_mode(drvdata->csdev)) {
>>>    		spin_lock(&drvdata->spinlock);
>>> -		for (i = 0; i < drvdata->nr_cntr; i++)
>>> -			ret += sprintf(buf, "counter %d: %x\n",
>>> -				       i, config->cntr_val[i]);
>>> +		val = config->cntr_val[config->cntr_idx];
>>>    		spin_unlock(&drvdata->spinlock);
>>> -		return ret;
>>> -	}
>>> -
>>> -	for (i = 0; i < drvdata->nr_cntr; i++) {
>>> -		val = etm_readl(drvdata, ETMCNTVRn(i));
>>> -		ret += sprintf(buf, "counter %d: %x\n", i, val);
>>> +	} else {
>>> +		val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx));
>>>    	}
>>> -	return ret;
>>> +	return sysfs_emit(buf, "%#x\n", val);
>>>    }
>>>    static ssize_t cntr_val_store(struct device *dev,
>>
>> Reviewed-by: James Clark <james.clark@linaro.org>
>>
> Thanks for the review!
> Is there anything else I need to do for this fix to land?

Thanks for the patch, I will queue this for the next release (v7.1).

Suzuki

> 
> Regards,
> Kuan-Wei
> 

Re: [PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

[Kuan-Wei Chiu]

Hi Suzuki,

On Mon, Feb 02, 2026 at 09:33:59AM +0000, Suzuki K Poulose wrote:
> Hello
> 
> On 02/02/2026 05:09, Kuan-Wei Chiu wrote:
> > On Tue, Dec 02, 2025 at 09:26:19AM +0000, James Clark wrote:
> > > 
> > > 
> > > On 02/12/2025 8:26 am, Kuan-Wei Chiu wrote:
> > > > The cntr_val_show() function was intended to print the values of all
> > > > counters using a loop. However, due to a buffer overwrite issue with
> > > > sprintf(), it effectively only displayed the value of the last counter.
> > > > 
> > > > The companion function, cntr_val_store(), allows users to modify a
> > > > specific counter selected by 'cntr_idx'. To maintain consistency
> > > > between read and write operations and to align with the ETM4x driver
> > > > behavior, modify cntr_val_show() to report only the value of the
> > > > currently selected counter.
> > > > 
> > > > This change removes the loop and the "counter %d:" prefix, printing
> > > > only the hexadecimal value. It also adopts sysfs_emit() for standard
> > > > sysfs output formatting.
> > > > 
> > > > Fixes: a939fc5a71ad ("coresight-etm: add CoreSight ETM/PTM driver")
> > > > Cc: stable@vger.kernel.org
> > > > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > > > ---
> > > > Build test only.
> > > > 
> > > > Changes in v3:
> > > > - Switch format specifier to %#x to include the 0x prefix.
> > > > - Add Cc stable
> > > > 
> > > > v2: https://lore.kernel.org/lkml/20251201095228.1905489-1-visitorckw@gmail.com/
> > > > 
> > > >    .../hwtracing/coresight/coresight-etm3x-sysfs.c   | 15 ++++-----------
> > > >    1 file changed, 4 insertions(+), 11 deletions(-)
> > > > 
> > > > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > index 762109307b86..b3c67e96a82a 100644
> > > > --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > @@ -717,26 +717,19 @@ static DEVICE_ATTR_RW(cntr_rld_event);
> > > >    static ssize_t cntr_val_show(struct device *dev,
> > > >    			     struct device_attribute *attr, char *buf)
> > > >    {
> > > > -	int i, ret = 0;
> > > >    	u32 val;
> > > >    	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > > >    	struct etm_config *config = &drvdata->config;
> > > >    	if (!coresight_get_mode(drvdata->csdev)) {
> > > >    		spin_lock(&drvdata->spinlock);
> > > > -		for (i = 0; i < drvdata->nr_cntr; i++)
> > > > -			ret += sprintf(buf, "counter %d: %x\n",
> > > > -				       i, config->cntr_val[i]);
> > > > +		val = config->cntr_val[config->cntr_idx];
> > > >    		spin_unlock(&drvdata->spinlock);
> > > > -		return ret;
> > > > -	}
> > > > -
> > > > -	for (i = 0; i < drvdata->nr_cntr; i++) {
> > > > -		val = etm_readl(drvdata, ETMCNTVRn(i));
> > > > -		ret += sprintf(buf, "counter %d: %x\n", i, val);
> > > > +	} else {
> > > > +		val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx));
> > > >    	}
> > > > -	return ret;
> > > > +	return sysfs_emit(buf, "%#x\n", val);
> > > >    }
> > > >    static ssize_t cntr_val_store(struct device *dev,
> > > 
> > > Reviewed-by: James Clark <james.clark@linaro.org>
> > > 
> > Thanks for the review!
> > Is there anything else I need to do for this fix to land?
> 
> Thanks for the patch, I will queue this for the next release (v7.1).
>
Just a gentle ping.

Since the v7.1 merge window is presumably opening in about a week, I
noticed this patch isn't in linux-next yet and wanted to send a quick
reminder. Thanks.

Regards,
Kuan-Wei

Re: [PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

[Kuan-Wei Chiu]

Hi Suzuki,

On Fri, Apr 03, 2026 at 04:57:59PM +0800, Kuan-Wei Chiu wrote:
> Hi Suzuki,
> 
> On Mon, Feb 02, 2026 at 09:33:59AM +0000, Suzuki K Poulose wrote:
> > Hello
> > 
> > On 02/02/2026 05:09, Kuan-Wei Chiu wrote:
> > > On Tue, Dec 02, 2025 at 09:26:19AM +0000, James Clark wrote:
> > > > 
> > > > 
> > > > On 02/12/2025 8:26 am, Kuan-Wei Chiu wrote:
> > > > > The cntr_val_show() function was intended to print the values of all
> > > > > counters using a loop. However, due to a buffer overwrite issue with
> > > > > sprintf(), it effectively only displayed the value of the last counter.
> > > > > 
> > > > > The companion function, cntr_val_store(), allows users to modify a
> > > > > specific counter selected by 'cntr_idx'. To maintain consistency
> > > > > between read and write operations and to align with the ETM4x driver
> > > > > behavior, modify cntr_val_show() to report only the value of the
> > > > > currently selected counter.
> > > > > 
> > > > > This change removes the loop and the "counter %d:" prefix, printing
> > > > > only the hexadecimal value. It also adopts sysfs_emit() for standard
> > > > > sysfs output formatting.
> > > > > 
> > > > > Fixes: a939fc5a71ad ("coresight-etm: add CoreSight ETM/PTM driver")
> > > > > Cc: stable@vger.kernel.org
> > > > > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > > > > ---
> > > > > Build test only.
> > > > > 
> > > > > Changes in v3:
> > > > > - Switch format specifier to %#x to include the 0x prefix.
> > > > > - Add Cc stable
> > > > > 
> > > > > v2: https://lore.kernel.org/lkml/20251201095228.1905489-1-visitorckw@gmail.com/
> > > > > 
> > > > >    .../hwtracing/coresight/coresight-etm3x-sysfs.c   | 15 ++++-----------
> > > > >    1 file changed, 4 insertions(+), 11 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > > index 762109307b86..b3c67e96a82a 100644
> > > > > --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > > +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > > @@ -717,26 +717,19 @@ static DEVICE_ATTR_RW(cntr_rld_event);
> > > > >    static ssize_t cntr_val_show(struct device *dev,
> > > > >    			     struct device_attribute *attr, char *buf)
> > > > >    {
> > > > > -	int i, ret = 0;
> > > > >    	u32 val;
> > > > >    	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > > > >    	struct etm_config *config = &drvdata->config;
> > > > >    	if (!coresight_get_mode(drvdata->csdev)) {
> > > > >    		spin_lock(&drvdata->spinlock);
> > > > > -		for (i = 0; i < drvdata->nr_cntr; i++)
> > > > > -			ret += sprintf(buf, "counter %d: %x\n",
> > > > > -				       i, config->cntr_val[i]);
> > > > > +		val = config->cntr_val[config->cntr_idx];
> > > > >    		spin_unlock(&drvdata->spinlock);
> > > > > -		return ret;
> > > > > -	}
> > > > > -
> > > > > -	for (i = 0; i < drvdata->nr_cntr; i++) {
> > > > > -		val = etm_readl(drvdata, ETMCNTVRn(i));
> > > > > -		ret += sprintf(buf, "counter %d: %x\n", i, val);
> > > > > +	} else {
> > > > > +		val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx));
> > > > >    	}
> > > > > -	return ret;
> > > > > +	return sysfs_emit(buf, "%#x\n", val);
> > > > >    }
> > > > >    static ssize_t cntr_val_store(struct device *dev,
> > > > 
> > > > Reviewed-by: James Clark <james.clark@linaro.org>
> > > > 
> > > Thanks for the review!
> > > Is there anything else I need to do for this fix to land?
> > 
> > Thanks for the patch, I will queue this for the next release (v7.1).
> >
> Just a gentle ping.
> 
> Since the v7.1 merge window is presumably opening in about a week, I
> noticed this patch isn't in linux-next yet and wanted to send a quick
> reminder. Thanks.
> 
This patch still applies cleanly on top of linux-next.
I suspect this patch may have fallen through the cracks.
Would you still be willing to pick it up?

Regards,
Kuan-Wei