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Subject[PATCH v4 02/17] perf ftrace: add option '-F/--funcs' to list available functions
Date
This adds an option '-F/--funcs' to list all available functions to trace,
which is read from tracing file 'available_filter_functions'.

$ sudo ./perf ftrace -F | head
trace_initcall_finish_cb
initcall_blacklisted
do_one_initcall
do_one_initcall
trace_initcall_start_cb
run_init_process
try_to_run_init_process
match_dev_by_label
match_dev_by_uuid
rootfs_init_fs_context

Signed-off-by: Changbin Du <changbin.du@gmail.com>

---
v2: option name '-l/--list-functions' -> '-F/--funcs'
---
tools/perf/Documentation/perf-ftrace.txt | 4 +++
tools/perf/builtin-ftrace.c | 43 ++++++++++++++++++++++++
2 files changed, 47 insertions(+)

diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
index 952e46669168..d79560dea19f 100644
--- a/tools/perf/Documentation/perf-ftrace.txt
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -30,6 +30,10 @@ OPTIONS
--verbose=::
Verbosity level.

+-F::
+--funcs::
+ List all available functions to trace.
+
-p::
--pid=::
Trace on existing process id (comma separated list).
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 5f53da87040d..244cc8e6bd60 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -32,6 +32,7 @@ struct perf_ftrace {
struct evlist *evlist;
struct target target;
const char *tracer;
+ bool list_avail_functions;
struct list_head filters;
struct list_head notrace;
struct list_head graph_funcs;
@@ -127,6 +128,43 @@ static int append_tracing_file(const char *name, const char *val)
return __write_tracing_file(name, val, true);
}

+static int read_tracing_file_to_stdout(const char *name)
+{
+ char buf[4096];
+ char *file;
+ int fd;
+ int ret = -1;
+
+ file = get_tracing_file(name);
+ if (!file) {
+ pr_debug("cannot get tracing file: %s\n", name);
+ return -1;
+ }
+
+ fd = open(file, O_RDONLY);
+ if (fd < 0) {
+ pr_debug("cannot open tracing file: %s: %s\n",
+ name, str_error_r(errno, buf, sizeof(buf)));
+ goto out;
+ }
+
+ /* read contents to stdout */
+ while (true) {
+ int n = read(fd, buf, sizeof(buf));
+ if (n <= 0)
+ goto out_close;
+ if (fwrite(buf, n, 1, stdout) != 1)
+ goto out_close;
+ }
+ ret = 0;
+
+out_close:
+ close(fd);
+out:
+ put_tracing_file(file);
+ return ret;
+}
+
static int reset_tracing_cpu(void);
static void reset_tracing_filters(void);

@@ -301,6 +339,9 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
signal(SIGCHLD, sig_handler);
signal(SIGPIPE, sig_handler);

+ if (ftrace->list_avail_functions)
+ return read_tracing_file_to_stdout("available_filter_functions");
+
if (reset_tracing_files(ftrace) < 0) {
pr_err("failed to reset ftrace\n");
goto out;
@@ -470,6 +511,8 @@ int cmd_ftrace(int argc, const char **argv)
const struct option ftrace_options[] = {
OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
"tracer to use: function or function_graph (This option is deprecated)"),
+ OPT_BOOLEAN('F', "funcs", &ftrace.list_avail_functions,
+ "Show available functions to filter"),
OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
"trace on existing process id"),
OPT_INCR('v', "verbose", &verbose,
--
2.25.1
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