On Fri, Aug 14, 2020 at 08:35:35AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sat, Aug 08, 2020 at 10:31:25AM +0800, Changbin Du escreveu:
> > 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...@gmail.com>
> >
> > ---
> > v3: fix return value issue.
> > v2: option name '-l/--list-functions' -> '-F/--funcs'
> > ---
> > tools/perf/Documentation/perf-ftrace.txt | 4 +++
> > tools/perf/builtin-ftrace.c | 46 ++++++++++++++++++++++++
> > 2 files changed, 50 insertions(+)
> >
> > diff --git a/tools/perf/Documentation/perf-ftrace.txt
> > b/tools/perf/Documentation/perf-ftrace.txt
> > index 821d4d334a09..4f5628445a63 100644
> > --- 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 048a11192b59..1ebf71ecc1a8 100644
> > --- 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"),
>
> A boolean? I guess this can be a first step, but why not do it like
> 'perf probe' and accept a patterna? Allows for less typing:
>
> # perf probe -h -F
>
> -F, --funcs <[FILTER]>
> Show potential probe-able functions.
>
> [root@quaco ~]#
>
> # perf probe -F '*btf_parse*'
> btf_parse_hdr
> btf_parse_str_sec
> btf_parse_vmlinux
> #
> # perf ftrace -F | grep btf_parse
> btf_parse_str_sec
> btf_parse_hdr
> btf_parse_vmlinux
> #
>
> I'm applying this to make progress, but please consider sending a patch
> to make this behave in the same way as 'perf probe'.
>
No problem, I'll try to provide similar behaviour for this. Thanks.
> - Arnaldo
>
>
> > OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
> > "trace on existing process id"),
> > OPT_INCR('v', "verbose", &verbose,
> > --
> > 2.25.1
> >
>
> --
>
> - Arnaldo
--
Cheers,
Changbin Du
