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

[Suzuki K Poulose]

On 08/06/2026 17:55, Kuan-Wei Chiu wrote:
> 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 at vger.kernel.org
>>>>>> Signed-off-by: Kuan-Wei Chiu <visitorckw at 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 at 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?

Apologies, it did. I will pick this up, if we have sufficient fixes,
I might send it as fixes for v7.2, otherwise , queue it for v7.3

Once again, apologies.

Suzuki


> 
> Regards,
> Kuan-Wei