2022-04-29 23:30:14

by German Gomez

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

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 <[email protected]>
Signed-off-by: German Gomez <[email protected]>
---
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

2022-05-02 23:46:35

by Leo Yan

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

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 <[email protected]>
> Signed-off-by: German Gomez <[email protected]>

Reviewed-by: Leo Yan <[email protected]>

2022-05-03 00:44:49

by Mathieu Poirier

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

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 <[email protected]>
> Signed-off-by: German Gomez <[email protected]>
> ---
> 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
>