[PATCH 0/2] coresight: etm4x: Expose default timestamp source in sysfs

[PATCH 0/2] coresight: etm4x: Expose default timestamp source in sysfs

[German Gomez]

Hi,

I'm Sending this sysfs addition to the etm4x driver in order to expose
the timestamp source of the trace (given by the TRFCR_ELx.TS register).

As mentioned in [1/2], having this information is useful for assigning
Kernel times to the perf samples.

Thanks,
German

German Gomez (3):
  coresight: etm4x: Expose default timestamp source in sysfs
  coresight: etm4x: docs: Add documentation for 'ts_source' sysfs
    interface
  perf cs_etm: Store ts_source in AUXTRACE_INFO fields

 .../testing/sysfs-bus-coresight-devices-etm4x |  8 +++
 .../coresight/coresight-etm4x-reference.rst   | 14 ++++
 arch/arm64/include/asm/sysreg.h               |  1 +
 .../coresight/coresight-etm4x-sysfs.c         | 34 ++++++++++
 tools/perf/arch/arm/util/cs-etm.c             | 64 +++++++++++++++++--
 tools/perf/util/cs-etm.c                      | 61 +++++++++---------
 tools/perf/util/cs-etm.h                      | 13 +++-
 7 files changed, 159 insertions(+), 36 deletions(-)

-- 
2.25.1

[PATCH 1/2] coresight: etm4x: Expose default timestamp source in sysfs

[German Gomez]

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;
+	}
+
+	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

[PATCH 2/2] coresight: etm4x: docs: Add documentation for 'ts_source' sysfs interface

[German Gomez]

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

Re: [PATCH 1/2] coresight: etm4x: Expose default timestamp source in sysfs

[Leo Yan]

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>

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

Re: [PATCH 2/2] coresight: etm4x: docs: Add documentation for 'ts_source' sysfs interface

[Mathieu Poirier]

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
> 

Re: [PATCH 1/2] coresight: etm4x: Expose default timestamp source in sysfs

[Mathieu Poirier]

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
>