perf scripting python: Add function to get a config value

This can be used to get config values like which objdump Perf uses for
disassembly.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Tested-by: Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
Cc: Ben Gainey <ben.gainey@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Ruidong Tian <tianruidong@linux.alibaba.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Benjamin Gray <bgray@linux.ibm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: coresight@lists.linaro.org
Cc: John Garry <john.g.garry@oracle.com>
Cc: scclevenger@os.amperecomputing.com
Link: https://lore.kernel.org/r/20240916135743.1490403-4-james.clark@linaro.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

4 files changed, 35 insertions, 1 deletions

diff --git a/tools/perf/Documentation/perf-script-python.txt b/tools/perf/Documentation/perf-script-python.txt
index 13e37e9385ee..27a1cac6fe76 100644
--- a/tools/perf/Documentation/perf-script-python.txt
+++ b/tools/perf/Documentation/perf-script-python.txt
@@ -624,7 +624,7 @@ as perf_trace_context.perf_script_context .
  perf_set_itrace_options(context, itrace_options) - set --itrace options if they have not been set already
  perf_sample_srcline(context) - returns source_file_name, line_number
  perf_sample_srccode(context) - returns source_file_name, line_number, source_line
-
+ perf_config_get(config_name) - returns the value of the named config item, or None if unset
 
 Util.py Module
 ~~~~~~~~~~~~~~
diff --git a/tools/perf/scripts/python/Perf-Trace-Util/Context.c b/tools/perf/scripts/python/Perf-Trace-Util/Context.c
index 3954bd1587ce..01f54d6724a5 100644
--- a/tools/perf/scripts/python/Perf-Trace-Util/Context.c
+++ b/tools/perf/scripts/python/Perf-Trace-Util/Context.c
@@ -12,6 +12,7 @@
 #define PY_SSIZE_T_CLEAN
 
 #include <Python.h>
+#include "../../../util/config.h"
 #include "../../../util/trace-event.h"
 #include "../../../util/event.h"
 #include "../../../util/symbol.h"
@@ -182,6 +183,15 @@ static PyObject *perf_sample_srccode(PyObject *obj, PyObject *args)
 	return perf_sample_src(obj, args, true);
 }
 
+static PyObject *__perf_config_get(PyObject *obj, PyObject *args)
+{
+	const char *config_name;
+
+	if (!PyArg_ParseTuple(args, "s", &config_name))
+		return NULL;
+	return Py_BuildValue("s", perf_config_get(config_name));
+}
+
 static PyMethodDef ContextMethods[] = {
 #ifdef HAVE_LIBTRACEEVENT
 	{ "common_pc", perf_trace_context_common_pc, METH_VARARGS,
@@ -199,6 +209,7 @@ static PyMethodDef ContextMethods[] = {
 	  METH_VARARGS,	"Get source file name and line number."},
 	{ "perf_sample_srccode", perf_sample_srccode,
 	  METH_VARARGS,	"Get source file name, line number and line."},
+	{ "perf_config_get", __perf_config_get, METH_VARARGS, "Get perf config entry"},
 	{ NULL, NULL, 0, NULL}
 };
 
diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
index 7a650de0db83..68f9407ca74b 100644
--- a/tools/perf/util/config.c
+++ b/tools/perf/util/config.c
@@ -912,6 +912,7 @@ void set_buildid_dir(const char *dir)
 struct perf_config_scan_data {
 	const char *name;
 	const char *fmt;
+	const char *value;
 	va_list args;
 	int ret;
 };
@@ -939,3 +940,24 @@ int perf_config_scan(const char *name, const char *fmt, ...)
 
 	return d.ret;
 }
+
+static int perf_config_get_cb(const char *var, const char *value, void *data)
+{
+	struct perf_config_scan_data *d = data;
+
+	if (!strcmp(var, d->name))
+		d->value = value;
+
+	return 0;
+}
+
+const char *perf_config_get(const char *name)
+{
+	struct perf_config_scan_data d = {
+		.name = name,
+		.value = NULL,
+	};
+
+	perf_config(perf_config_get_cb, &d);
+	return d.value;
+}
diff --git a/tools/perf/util/config.h b/tools/perf/util/config.h
index 2e5e808928a5..9971313d61c1 100644
--- a/tools/perf/util/config.h
+++ b/tools/perf/util/config.h
@@ -30,6 +30,7 @@ typedef int (*config_fn_t)(const char *, const char *, void *);
 int perf_default_config(const char *, const char *, void *);
 int perf_config(config_fn_t fn, void *);
 int perf_config_scan(const char *name, const char *fmt, ...) __scanf(2, 3);
+const char *perf_config_get(const char *name);
 int perf_config_set(struct perf_config_set *set,
 		    config_fn_t fn, void *data);
 int perf_config_int(int *dest, const char *, const char *);