Re: [PATCH 2/5] coresight-etm4x: Change the name of the ctxid_val to ctxid_pid

[Mathieu Poirier]

On 26 August 2015 at 11:57, Christopher Covington <cov@xxxxxxxxxxxxxx> wrote:
> On 07/07/2015 04:41 AM, Chunyan Zhang wrote:
>> 'ctxid_val' array was used to store the value of ETM context ID comparator
>> which actually stores the process ID to be traced, so using 'ctxid_pid' as
>> its name instead make it easier to understand.
>
> Previous discussion with some ARM folks has led me to believe there isn't a
> guarantee that the Context ID Register will always have a PID. Why not allow
> filtering on thread group ID, session ID, cgroup related identifiers, etc.?

Coresight tracers only support contextID tracing.  The HW
automatically does the match between the contextID comparator register
in the tracer with the contextID register of the core.  Tracing is
enabled if both values match (and the tracer is configured to do so).

>
>> This patch also changes the ABI, it is normally not allowed, but
>> fortunately it is a testing ABI and very new for now. Nevertheless,
>> if you don't think it should be changed, we could always add an alias
>> for userspace.
>>
>> Signed-off-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
>> Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>
>> ---
>>  .../ABI/testing/sysfs-bus-coresight-devices-etm4x    |  2 +-
>>  drivers/hwtracing/coresight/coresight-etm4x.c        | 20 ++++++++++----------
>>  drivers/hwtracing/coresight/coresight-etm4x.h        |  4 ++--
>>  3 files changed, 13 insertions(+), 13 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x
>> index 2fe2e3d..2355ed8 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x
>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x
>> @@ -249,7 +249,7 @@ KernelVersion:    4.01
>>  Contact:     Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
>>  Description: (RW) Select which context ID comparator to work with.
>>
>> -What:                /sys/bus/coresight/devices/<memory_map>.etm/ctxid_val
>> +What:                /sys/bus/coresight/devices/<memory_map>.etm/ctxid_pid
>>  Date:                April 2015
>>  KernelVersion:       4.01
>>  Contact:     Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
>> index 1312e99..9afbda5 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
>> @@ -155,7 +155,7 @@ static void etm4_enable_hw(void *info)
>>                              drvdata->base + TRCACATRn(i));
>>       }
>>       for (i = 0; i < drvdata->numcidc; i++)
>> -             writeq_relaxed(drvdata->ctxid_val[i],
>> +             writeq_relaxed(drvdata->ctxid_pid[i],
>>                              drvdata->base + TRCCIDCVRn(i));
>>       writel_relaxed(drvdata->ctxid_mask0, drvdata->base + TRCCIDCCTLR0);
>>       writel_relaxed(drvdata->ctxid_mask1, drvdata->base + TRCCIDCCTLR1);
>> @@ -507,7 +507,7 @@ static ssize_t reset_store(struct device *dev,
>>
>>       drvdata->ctxid_idx = 0x0;
>>       for (i = 0; i < drvdata->numcidc; i++)
>> -             drvdata->ctxid_val[i] = 0x0;
>> +             drvdata->ctxid_pid[i] = 0x0;
>>       drvdata->ctxid_mask0 = 0x0;
>>       drvdata->ctxid_mask1 = 0x0;
>>
>> @@ -1815,7 +1815,7 @@ static ssize_t ctxid_idx_store(struct device *dev,
>>  }
>>  static DEVICE_ATTR_RW(ctxid_idx);
>>
>> -static ssize_t ctxid_val_show(struct device *dev,
>> +static ssize_t ctxid_pid_show(struct device *dev,
>>                             struct device_attribute *attr,
>>                             char *buf)
>>  {
>> @@ -1825,12 +1825,12 @@ static ssize_t ctxid_val_show(struct device *dev,
>>
>>       spin_lock(&drvdata->spinlock);
>>       idx = drvdata->ctxid_idx;
>> -     val = (unsigned long)drvdata->ctxid_val[idx];
>> +     val = (unsigned long)drvdata->ctxid_pid[idx];
>>       spin_unlock(&drvdata->spinlock);
>>       return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
>>  }
>>
>> -static ssize_t ctxid_val_store(struct device *dev,
>> +static ssize_t ctxid_pid_store(struct device *dev,
>>                              struct device_attribute *attr,
>>                              const char *buf, size_t size)
>>  {
>> @@ -1850,11 +1850,11 @@ static ssize_t ctxid_val_store(struct device *dev,
>>
>>       spin_lock(&drvdata->spinlock);
>>       idx = drvdata->ctxid_idx;
>> -     drvdata->ctxid_val[idx] = (u64)val;
>> +     drvdata->ctxid_pid[idx] = (u64)val;
>>       spin_unlock(&drvdata->spinlock);
>>       return size;
>>  }
>> -static DEVICE_ATTR_RW(ctxid_val);
>> +static DEVICE_ATTR_RW(ctxid_pid);
>>
>>  static ssize_t ctxid_masks_show(struct device *dev,
>>                               struct device_attribute *attr,
>> @@ -1949,7 +1949,7 @@ static ssize_t ctxid_masks_store(struct device *dev,
>>                */
>>               for (j = 0; j < 8; j++) {
>>                       if (maskbyte & 1)
>> -                             drvdata->ctxid_val[i] &= ~(0xFF << (j * 8));
>> +                             drvdata->ctxid_pid[i] &= ~(0xFF << (j * 8));
>>                       maskbyte >>= 1;
>>               }
>>               /* Select the next ctxid comparator mask value */
>> @@ -2193,7 +2193,7 @@ static struct attribute *coresight_etmv4_attrs[] = {
>>       &dev_attr_res_idx.attr,
>>       &dev_attr_res_ctrl.attr,
>>       &dev_attr_ctxid_idx.attr,
>> -     &dev_attr_ctxid_val.attr,
>> +     &dev_attr_ctxid_pid.attr,
>>       &dev_attr_ctxid_masks.attr,
>>       &dev_attr_vmid_idx.attr,
>>       &dev_attr_vmid_val.attr,
>> @@ -2514,7 +2514,7 @@ static void etm4_init_default_data(struct etmv4_drvdata *drvdata)
>>       }
>>
>>       for (i = 0; i < drvdata->numcidc; i++)
>> -             drvdata->ctxid_val[i] = 0x0;
>> +             drvdata->ctxid_pid[i] = 0x0;
>>       drvdata->ctxid_mask0 = 0x0;
>>       drvdata->ctxid_mask1 = 0x0;
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
>> index e08e983..1e8fb36 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
>> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
>> @@ -265,7 +265,7 @@
>>   * @addr_type:       Current status of the comparator register.
>>   * @ctxid_idx:       Context ID index selector.
>>   * @ctxid_size:      Size of the context ID field to consider.
>> - * @ctxid_val:       Value of the context ID comparator.
>> + * @ctxid_pid:       Value of the context ID comparator.
>>   * @ctxid_mask0:Context ID comparator mask for comparator 0-3.
>>   * @ctxid_mask1:Context ID comparator mask for comparator 4-7.
>>   * @vmid_idx:        VM ID index selector.
>> @@ -352,7 +352,7 @@ struct etmv4_drvdata {
>>       u8                              addr_type[ETM_MAX_SINGLE_ADDR_CMP];
>>       u8                              ctxid_idx;
>>       u8                              ctxid_size;
>> -     u64                             ctxid_val[ETMv4_MAX_CTXID_CMP];
>> +     u64                             ctxid_pid[ETMv4_MAX_CTXID_CMP];
>>       u32                             ctxid_mask0;
>>       u32                             ctxid_mask1;
>>       u8                              vmid_idx;
>>
>
>
> --
> Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
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