perf python: Port syscall-counts to perf module

Port tools/perf/scripts/python/syscall-counts.py to a standalone script
in tools/perf/python/ using the perf module. Avoiding the embedded
interpreter and per-event dictionary allocation overhead improves
execution speed by ~4x:

```
$ perf record -e raw_syscalls:sys_enter -a sleep 1
...
$ time perf script tools/perf/scripts/python/syscall-counts.py perf
...
real    0m3.887s
user    0m3.578s
sys     0m0.308s
$ time python3 tools/perf/python/syscall-counts.py perf
...
real    0m0.953s
user    0m0.905s
sys     0m0.048s
```

Additional improvements compared to the legacy script:
- Resolve syscall names using perf.syscall_name(id, session.e_machine)
  instead of host python-audit / Util.py tables, enabling accurate
  cross-architecture perf.data analysis without external dependencies.
- Support both raw_syscalls:sys_enter (sample.id) and individual
  syscalls:sys_enter_* tracepoints (sample.__syscall_nr / sample.nr),
  filtering out invalid/corrupt (> 0xffff or negative) syscall numbers.
- Add argparse CLI options (-i/--input and optional comm filter).

Add a shell test (test_syscall_counts_python.sh) to verify the
standalone script. The legacy script and its bin wrapper are retained
temporarily during the transition to maintain bisectability and are
removed once all scripts are migrated.

Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 81 insertions, 0 deletions

diff --git a/tools/perf/tests/shell/test_syscall_counts_python.sh b/tools/perf/tests/shell/test_syscall_counts_python.sh
new file mode 100755
index 000000000000..0c4b75499209
--- /dev/null
+++ b/tools/perf/tests/shell/test_syscall_counts_python.sh
@@ -0,0 +1,81 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# syscall-counts python test
+
+set -e
+
+shelldir=$(dirname "$0")
+# shellcheck source=lib/setup_python.sh
+. "${shelldir}"/lib/setup_python.sh
+
+# If we don't have the perf python module, we can't test
+if ! "$PYTHON" -c 'import perf' > /dev/null 2>&1; then
+	echo "Skipping test, perf python module not found"
+	exit 2
+fi
+
+script_dir="$(dirname "$0")/../../python"
+script_path="${script_dir}/syscall-counts.py"
+
+if ! perf check feature -q libtraceevent > /dev/null 2>&1; then
+	echo "Skipping test, libtraceevent is disabled"
+	exit 2
+fi
+
+if [ ! -f "$script_path" ]; then
+	echo "Skipping test, syscall-counts.py not found at $script_path"
+	exit 2
+fi
+
+err=0
+temp_data=""
+temp_out=""
+
+cleanup() {
+	rm -f "${temp_data}" "${temp_out}"
+}
+
+trap 'cleanup' EXIT TERM INT
+
+temp_data=$(mktemp /tmp/perf.data.XXXXXX)
+temp_out=$(mktemp /tmp/perf.out.XXXXXX)
+
+test_file_mode() {
+	echo "Testing syscall-counts.py..."
+	# Some systems might not have raw_syscalls:sys_enter (e.g. stripped kernels or permissions)
+	if ! perf list | grep -q raw_syscalls:sys_enter; then
+		echo "Skipping test, raw_syscalls:sys_enter not found"
+		exit 2
+	fi
+
+	# Generate some syscall events
+	if ! perf record -e raw_syscalls:sys_enter -o "${temp_data}" -- sleep 0.5 2>/dev/null; then
+		echo "perf record failed (permissions?), skipping file mode test."
+		exit 2
+	fi
+
+	if ! "$PYTHON" "$script_path" -i "${temp_data}" > "${temp_out}"; then
+		echo "File mode test failed."
+		err=1
+	elif ! grep -E -q "^[a-zA-Z0-9_]+ +[0-9]+$" "${temp_out}"; then
+		echo "File mode output validation failed."
+		err=1
+	else
+		echo "File mode test passed."
+	fi
+
+	# Test with a comm argument
+	if ! "$PYTHON" "$script_path" -i "${temp_data}" "sleep" > "${temp_out}"; then
+		echo "Comm filter test failed."
+		err=1
+	elif ! grep -E -q "^[a-zA-Z0-9_]+ +[0-9]+$" "${temp_out}"; then
+		echo "Comm filter output validation failed."
+		err=1
+	else
+		echo "Comm filter test passed."
+	fi
+}
+
+test_file_mode
+
+exit $err