On Fri, Apr 29, 2022 at 01:30:59PM +0100, German Gomez wrote:

Add a new sysfs interface in /sys/bus/coresight/devices/etm<N>/ts_source indicating the configured timestamp source when the ETM device driver was probed.

The perf tool will use this information to detect if the trace data timestamp matches the kernel time, enabling correlation of CoreSight trace with perf events.

Suggested-by: Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: German Gomez german.gomez@arm.com

---

arch/arm64/include/asm/sysreg.h | 1 + .../coresight/coresight-etm4x-sysfs.c | 34 +++++++++++++++++++ 2 files changed, 35 insertions(+)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 38508e507d73a..263a7bee06f9a 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -1146,6 +1146,7 @@ #define SYS_MPIDR_SAFE_VAL (BIT(31)) #define TRFCR_ELx_TS_SHIFT 5 +#define TRFCR_ELx_TS_MASK ((0x3UL) << TRFCR_ELx_TS_SHIFT) #define TRFCR_ELx_TS_VIRTUAL ((0x1UL) << TRFCR_ELx_TS_SHIFT) #define TRFCR_ELx_TS_GUEST_PHYSICAL ((0x2UL) << TRFCR_ELx_TS_SHIFT) #define TRFCR_ELx_TS_PHYSICAL ((0x3UL) << TRFCR_ELx_TS_SHIFT) diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c index a0640fa5c55bd..c0c375c0cfde2 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c @@ -2264,6 +2264,39 @@ static ssize_t cpu_show(struct device *dev, } static DEVICE_ATTR_RO(cpu); +static int etmv4_to_ts_source(struct etmv4_drvdata *drvdata) +{

• int val;
• if (!drvdata->trfcr)

• return -1;
  

• switch (drvdata->trfcr & TRFCR_ELx_TS_MASK) {
• case TRFCR_ELx_TS_VIRTUAL:
• case TRFCR_ELx_TS_GUEST_PHYSICAL:
• case TRFCR_ELx_TS_PHYSICAL:

• val = FIELD_GET(TRFCR_ELx_TS_MASK, drvdata->trfcr);
  

• break;
  

• default:

• val = -1;
  

• break;
  

• }

I don't think the above is big and/or complex enough to mandate a separate function - please move to ts_source_show().

• return val;

+}

+static ssize_t ts_source_show(struct device *dev,

• 	      struct device_attribute *attr,
  

• 	      char *buf)
  

+{

• int val;
• struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
• val = etmv4_to_ts_source(drvdata);
• return sysfs_emit(buf, "%d\n", val);

+} +static DEVICE_ATTR_RO(ts_source);

static struct attribute *coresight_etmv4_attrs[] = { &dev_attr_nr_pe_cmp.attr, &dev_attr_nr_addr_cmp.attr, @@ -2318,6 +2351,7 @@ static struct attribute *coresight_etmv4_attrs[] = { &dev_attr_vmid_val.attr, &dev_attr_vmid_masks.attr, &dev_attr_cpu.attr,

• &dev_attr_ts_source.attr, NULL,

}; -- 2.25.1

On Fri, Apr 29, 2022 at 01:31:00PM +0100, German Gomez wrote:

Sync sysfs documentation pages to include the new ts_source (timestamp source) interface.

Signed-off-by: German Gomez german.gomez@arm.com

.../ABI/testing/sysfs-bus-coresight-devices-etm4x | 8 ++++++++ .../trace/coresight/coresight-etm4x-reference.rst | 14 ++++++++++++++ 2 files changed, 22 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x index 8e53a32f81505..19ac9d6d2f504 100644 --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x @@ -516,3 +516,11 @@ Contact: Mathieu Poirier mathieu.poirier@linaro.org Description: (Read) Returns the number of special conditional P1 right-hand keys that the trace unit can use (0x194). The value is taken directly from the HW.

+What: /sys/bus/coresight/devices/etm<N>/ts_source +Date: April 2022 +KernelVersion: 5.18

This would be 5.19 and a (likely) date of July 2022.

+Contact: Mathieu Poirier mathieu.poirier@linaro.org

Suzuki's name should also be added.

Thanks, Mathieu

+Description: (Read) When FEAT_TRF is implemented, value of TRFCR_ELx.TS used for

• trace session. Otherwise -1 indicates an unknown time source. Check
  

• trcidr0.tssize to see if a global timestamp is available.
  

diff --git a/Documentation/trace/coresight/coresight-etm4x-reference.rst b/Documentation/trace/coresight/coresight-etm4x-reference.rst index d25dfe86af9bf..f016c7c29429b 100644 --- a/Documentation/trace/coresight/coresight-etm4x-reference.rst +++ b/Documentation/trace/coresight/coresight-etm4x-reference.rst @@ -71,6 +71,20 @@ the ‘TRC’ prefix.

---

+:File: ``ts_source`` (ro) +:Trace Registers: None. +:Notes:

• When FEAT_TRF is implemented, value of TRFCR_ELx.TS used for trace session. Otherwise -1
• indicates an unknown time source. Check trcidr0.tssize to see if a global timestamp is
• available.

+:Example:

• ``$> cat ts_source``
• ``$> 1``

+----

:File: ``addr_idx`` (rw) :Trace Registers: None. :Notes: -- 2.25.1