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perf: ftrace: Add filter support for option -F/--funcs
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Same as 'perf probe -F', this patch adds filter support for the ftrace
subcommand option '-F, --funcs <[FILTER]>'.

Here is an example that only lists functions which start with 'vfs_':

  $ sudo perf ftrace -F vfs_*
  vfs_fadvise
  vfs_fallocate
  vfs_truncate
  vfs_open
  vfs_setpos
  vfs_llseek
  vfs_readf
  vfs_writef
  ...

Suggested-by: Arnaldo Carvalho de Melo <[email protected]>
Signed-off-by: Changbin Du <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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changbindu authored and acmel committed Sep 4, 2020
1 parent ee7fe31 commit 2ae05fe
Showing 2 changed files with 80 additions and 7 deletions.
3 changes: 2 additions & 1 deletion tools/perf/Documentation/perf-ftrace.txt
Original file line number Diff line number Diff line change
@@ -33,7 +33,8 @@ OPTIONS

-F::
--funcs::
List all available functions to trace.
List available functions to trace. It accepts a pattern to
only list interested functions.

-p::
--pid=::
84 changes: 78 additions & 6 deletions tools/perf/builtin-ftrace.c
Original file line number Diff line number Diff line change
@@ -25,6 +25,7 @@
#include "target.h"
#include "cpumap.h"
#include "thread_map.h"
#include "strfilter.h"
#include "util/cap.h"
#include "util/config.h"
#include "util/units.h"
@@ -36,7 +37,6 @@ 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;
@@ -181,6 +181,40 @@ static int read_tracing_file_to_stdout(const char *name)
return ret;
}

static int read_tracing_file_by_line(const char *name,
void (*cb)(char *str, void *arg),
void *cb_arg)
{
char *line = NULL;
size_t len = 0;
char *file;
FILE *fp;

file = get_tracing_file(name);
if (!file) {
pr_debug("cannot get tracing file: %s\n", name);
return -1;
}

fp = fopen(file, "r");
if (fp == NULL) {
pr_debug("cannot open tracing file: %s\n", name);
put_tracing_file(file);
return -1;
}

while (getline(&line, &len, fp) != -1) {
cb(line, cb_arg);
}

if (line)
free(line);

fclose(fp);
put_tracing_file(file);
return 0;
}

static int write_tracing_file_int(const char *name, int value)
{
char buf[16];
@@ -557,9 +591,6 @@ 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;
@@ -683,6 +714,46 @@ static int perf_ftrace_config(const char *var, const char *value, void *cb)
return -1;
}

static void list_function_cb(char *str, void *arg)
{
struct strfilter *filter = (struct strfilter *)arg;

if (strfilter__compare(filter, str))
printf("%s", str);
}

static int opt_list_avail_functions(const struct option *opt __maybe_unused,
const char *str, int unset)
{
struct strfilter *filter;
const char *err = NULL;
int ret;

if (unset || !str)
return -1;

filter = strfilter__new(str, &err);
if (!filter)
return err ? -EINVAL : -ENOMEM;

ret = strfilter__or(filter, str, &err);
if (ret == -EINVAL) {
pr_err("Filter parse error at %td.\n", err - str + 1);
pr_err("Source: \"%s\"\n", str);
pr_err(" %*c\n", (int)(err - str + 1), '^');
strfilter__delete(filter);
return ret;
}

ret = read_tracing_file_by_line("available_filter_functions",
list_function_cb, filter);
strfilter__delete(filter);
if (ret < 0)
return ret;

exit(0);
}

static int parse_filter_func(const struct option *opt, const char *str,
int unset __maybe_unused)
{
@@ -817,8 +888,9 @@ 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_CALLBACK_DEFAULT('F', "funcs", NULL, "[FILTER]",
"Show available functions to filter",
opt_list_avail_functions, "*"),
OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
"Trace on existing process id"),
/* TODO: Add short option -t after -t/--tracer can be removed. */

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