Re: [PATCH] selftests: arm coresight: sysfsmode testing

[Shuah Khan <skhan@linuxfoundation.org>]

On 11/29/24 01:38, Linu Cherian wrote:
> Add sysfs mode selftest for ARM Coresight hardware tracer.

Please add details on what this test does in here. Include
the output from the test?

Does this test have dependencies on config? If it does, does
this test detect and skip if config isn't enabled?

> 
> Signed-off-by: Linu Cherian <lcherian@marvell.com>
> ---
>   .../drivers/hwtracing/coresight/Makefile      |   5 +
>   .../hwtracing/coresight/sysfs_test_trace.sh   | 144 ++++++++++++++++++
>   2 files changed, 149 insertions(+)
>   create mode 100644 tools/testing/selftests/drivers/hwtracing/coresight/Makefile
>   create mode 100755 tools/testing/selftests/drivers/hwtracing/coresight/sysfs_test_trace.sh
> 
> diff --git a/tools/testing/selftests/drivers/hwtracing/coresight/Makefile b/tools/testing/selftests/drivers/hwtracing/coresight/Makefile
> new file mode 100644
> index 000000000000..7dc68ae1c0a9
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/hwtracing/coresight/Makefile
> @@ -0,0 +1,5 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +TEST_PROGS = sysfs_test_trace.sh
> +
> +include ../../../lib.mk
> diff --git a/tools/testing/selftests/drivers/hwtracing/coresight/sysfs_test_trace.sh b/tools/testing/selftests/drivers/hwtracing/coresight/sysfs_test_trace.sh
> new file mode 100755
> index 000000000000..0d6307fff1d2
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/hwtracing/coresight/sysfs_test_trace.sh
> @@ -0,0 +1,144 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2024 Marvell.
> +
> +# Test Arm CoreSight trace capture in sysfs mode
> +# Based on tools/perf/tests/shell/test_arm_coresight.sh
> +
> +glb_err=0
> +
> +arm_cs_report() {
> +	if [ $2 != 0 ]; then
> +		echo "$1: FAIL"
> +		glb_err=$2
> +	else
> +		echo "$1: PASS"
> +	fi
> +}
> +
> +is_device_sink() {
> +	# If the node of "enable_sink" is existed under the device path, this
> +	# means the device is a sink device.
> +
> +	if [ -e "$1/enable_sink" ]; then
> +
> +		return 0
> +	else
> +		return 1
> +	fi
> +}
> +
> +# Configure sink for buffer mode
> +cfg_sink_buf_mode() {
> +	sink_dev=$1
> +	mode=$2
> +	# Set buffer mode if supported
> +	if [ -e "$sink_dev/buf_modes_available" ]; then
> +		cat $sink_dev/buf_modes_available | grep -E -q $mode
> +		if [ $? -eq 0 ]; then
> +			echo $mode > $sink_dev/buf_mode_preferred
> +			return 0
> +		fi
> +	fi
> +
> +	return 1
> +}
> +
> +run_app() {
> +
> +	taskset -c $1 dd if=/dev/urandom  of=/dev/null bs=1M count=64
> +}
> +
> +sysfs_trace() {
> +	src_dev=$1
> +	sink_dev=$2
> +	cpu=$3
> +
> +	# Enable sink device
> +	echo 1 > $sink_dev/enable_sink
> +	# Enable source device
> +	echo 1 > $src_dev/enable_source
> +
> +	# Run app to be traced
> +	run_app $cpu
> +
> +	# Read back trace data
> +	dd if=/dev/$sink_dev_name of=/tmp/tracedata
> +
> +	# Verify if read is successful
> +	err=$?
> +
> +	# Disable source device
> +	echo 0 > $src_dev/enable_source
> +
> +	# Diskable sink device
> +	echo 0 > $sink_dev/enable_sink
> +
> +	arm_cs_report "CoreSight path testing (CPU$cpu -> $sink_dev_name)" $err
> +}
> +
> +try_sysfs_trace_resrv_buf() {
> +	src_dev=$1
> +	sink_dev=$2
> +	cpu=$3
> +
> +	# Configure the resrved buffer mode if available
> +	cfg_sink_buf_mode $sink_dev "resrv"
> +	if [ $? -eq 0 ]; then
> +		echo "Running sysfs trace with resrv buf mode"
> +		sysfs_trace $src_dev $sink_dev $cpu
> +		# Restore buffer mode
> +		cfg_sink_buf_mode $sink_dev "auto"
> +		if [ $? -eq 1 ]; then
> +			echo "Failed to restore default buf mode"
> +		fi
> +	fi
> +}
> +
> +arm_cs_iterate_devices() {
> +	src_dev=$1
> +	cpu=$3
> +	for cdev in $2/connections/out\:*; do
> +
> +		# Skip testing if it's not a directory
> +		! [ -d $cdev ] && continue;
> +
> +		# Read out its symbol link file name
> +		sink_dev=`readlink -f $cdev`
> +
> +		# Extract device name from path, e.g.
> +		#   sink_dev = '/sys/devices/platform/20010000.etf/tmc_etf0'
> +		#     `> sink_dev_name = 'tmc_etf0'
> +		sink_dev_name=$(basename $sink_dev)
> +
> +		if is_device_sink $sink_dev; then
> +			# Run trace with resrv buf mode (if available)
> +			try_sysfs_trace_resrv_buf $src_dev $sink_dev $cpu
> +
> +			# Run the default mode
> +			echo "Running sysfs trace with default settings"
> +			sysfs_trace $src_dev $sink_dev $cpu
> +		fi
> +
> +		arm_cs_iterate_devices $src_dev $cdev $cpu
> +
> +	done
> +}
> +
> +arm_cs_etm_traverse_path_test() {
> +	# Iterate for every ETM device
> +	for dev in /sys/bus/event_source/devices/cs_etm/cpu*; do
> +		# Canonicalize the path
> +		dev=`readlink -f $dev`
> +
> +		# Find the ETM device belonging to which CPU
> +		cpu=`cat $dev/cpu`
> +
> +		# Use depth-first search (DFS) to iterate outputs
> +		arm_cs_iterate_devices $dev $dev $cpu
> +	done
> +}
> +
> +arm_cs_etm_traverse_path_test
> +
> +exit $glb_err

thanks,
-- Shuah