perf ftrace: Add option '-F/--funcs' to list available functions

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
  $

Committer notes:

This is the same command line option and for the same purpose as in
'perf probe'.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: http://lore.kernel.org/lkml/20200808023141.14227-3-changbin.du@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
index 821d4d3..4f56284 100644 (file)
--- a/tools/perf/Documentation/perf-ftrace.txt
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -31,6 +31,10 @@ 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 048a111..1ebf71e 100644 (file)
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -33,6 +33,7 @@ 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;
@@ -128,6 +129,46 @@ 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)
+                       break;
+               else 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);
 
@@ -302,6 +343,9 @@ 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;
@@ -487,6 +531,8 @@ int cmd_ftrace(int argc, const char **argv)
        const struct option ftrace_options[] = {
        OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
                   "tracer to use: function_graph(default) or function"),
+       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,