trace-cmd: Implement trace-cmd record function filtering

Now with "trace-cmd record -l func -g func -n func" you can add function
filtering to the trace.

Since -F and -f are taken, -l is used as "limit functions".

 -l func ; writes func into set_ftrace_filter

 -n func ; writes func into set_ftrace_notrace

 -g func ; writes func into set_graph_function

You can specify more than one function on the command line.

 trace-cmd record -p function -l sys_write -l sys_read

The above will set set_ftrace_filter to both sys_write and sys_read.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 67 insertions, 2 deletions

diff --git a/trace-cmd.c b/trace-cmd.c
index d91e212..2b246df 100644
--- a/trace-cmd.c
+++ b/trace-cmd.c
@@ -59,6 +59,15 @@ static int *pids;
 
 static int filter_task;
 
+struct func_list {
+        struct func_list *next;
+        const char *func;
+};
+
+static struct func_list *filter_funcs;
+static struct func_list *notrace_funcs;
+static struct func_list *graph_funcs;
+
 struct event_list {
         struct event_list *next;
         const char *event;
@@ -997,6 +1006,48 @@ static int trace_empty(void)
         return ret;
 }
 
+static void write_func_file(const char *file, struct func_list **list)
+{
+        struct func_list *item;
+        char *path;
+        int fd;
+
+        path = get_tracing_file(file);
+
+        fd = open(path, O_WRONLY | O_TRUNC);
+        if (fd < 0)
+                goto free;
+
+        while (*list) {
+                item = *list;
+                *list = item->next;
+                write(fd, item->func, strlen(item->func));
+                write(fd, " ", 1);
+                free(item);
+        }
+        close(fd);
+
+ free:
+        put_tracing_file(path);
+}
+
+static void set_funcs(void)
+{
+        write_func_file("set_ftrace_filter", &filter_funcs);
+        write_func_file("set_ftrace_notrace", &notrace_funcs);
+        write_func_file("set_graph_function", &graph_funcs);
+}
+
+static void add_func(struct func_list **list, const char *func)
+{
+        struct func_list *item;
+
+        item = malloc_or_die(sizeof(*item));
+        item->func = func;
+        item->next = *list;
+        *list = item;
+}
+
 void usage(char **argv)
 {
         char *arg = argv[0];
@@ -1009,11 +1060,15 @@ void usage(char **argv)
         printf("\n"
                "%s version %s\n\n"
                "usage:\n"
-               " %s record [-v][-e event [-f filter]][-p plugin][-F][-d][-o file][-s usecs][-O option ] [command ...]\n"
+               " %s record [-v][-e event [-f filter]][-p plugin][-F][-d][-o file] \\\n"
+               "           [-s usecs][-O option ][-l func][-g func][-n func][command ...]\n"
                "          -e run command with event enabled\n"
                "          -f filter for previous -e event\n"
                "          -p run command with plugin enabled\n"
                "          -F filter only on the given process\n"
+               "          -l filter function name\n"
+               "          -g set graph function\n"
+               "          -n do not trace function\n"
                "          -v will negate all -e after it (disable those events)\n"
                "          -d disable function tracer when running\n"
                "          -o data output file [default trace.dat]\n"
@@ -1105,7 +1160,7 @@ int main (int argc, char **argv)
                    (strcmp(argv[1], "start") == 0) ||
                    ((extract = strcmp(argv[1], "extract") == 0))) {
 
-                while ((c = getopt(argc-1, argv+1, "+he:f:Fp:do:O:s:v")) >= 0) {
+                while ((c = getopt(argc-1, argv+1, "+he:f:Fp:do:O:s:vg:l:n:")) >= 0) {
                         switch (c) {
                         case 'h':
                                 usage(argv);
@@ -1150,6 +1205,15 @@ int main (int argc, char **argv)
                                         usage(argv);
                                 neg_event = 1;
                                 break;
+                        case 'l':
+                                add_func(&filter_funcs, optarg);
+                                break;
+                        case 'n':
+                                add_func(&notrace_funcs, optarg);
+                                break;
+                        case 'g':
+                                add_func(&graph_funcs, optarg);
+                                break;
                         case 'p':
                                 if (plugin)
                                         die("only one plugin allowed");
@@ -1254,6 +1318,7 @@ int main (int argc, char **argv)
         if (!extract) {
                 fset = set_ftrace(!disable);
                 disable_all();
+                set_funcs();
 
                 if (events)
                         enable_events();