ftrace: add module globbing

Extend module command for function filter selection with globbing.
It uses the same globbing as function filter.

  sh# echo '*alloc*:mod:*' > set_ftrace_filter

Will trace any function with the letters 'alloc' in the name in any
module but not in kernel.

  sh# echo '!*alloc*:mod:ipv6' >> set_ftrace_filter

Will prevent from tracing functions with 'alloc' in the name from module
ipv6 (do not forget to append to set_ftrace_filter file).

  sh# echo '*alloc*:mod:!ipv6' > set_ftrace_filter

Will trace functions with 'alloc' in the name from kernel and any
module except ipv6.

  sh# echo '*alloc*:mod:!*' > set_ftrace_filter

Will trace any function with the letters 'alloc' in the name only from
kernel, but not from any module.

  sh# echo '*:mod:!*' > set_ftrace_filter
or
  sh# echo ':mod:!' > set_ftrace_filter

Will trace every function in the kernel, but will not trace functions
from any module.

  sh# echo '*:mod:*' > set_ftrace_filter
or
  sh# echo ':mod:' > set_ftrace_filter

As the opposite will trace all functions from all modules, but not from
kernel.

  sh# echo '*:mod:*snd*' > set_ftrace_filter

Will trace your sound drivers only (if any).

Link: http://lkml.kernel.org/r/1443545176-3215-4-git-send-email-0x7f454c46@gmail.com

Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
[ Made format changes ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 36 insertions, 15 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 450a5f5676ae..ea2725053771 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3485,19 +3485,37 @@ enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter)
 }
 
 static int
-ftrace_match_record(struct dyn_ftrace *rec,
-                char *mod, struct ftrace_glob *func_g)
+ftrace_match_record(struct dyn_ftrace *rec, struct ftrace_glob *func_g,
+                struct ftrace_glob *mod_g, int exclude_mod)
 {
         char str[KSYM_SYMBOL_LEN];
         char *modname;
 
         kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);
 
-        if (mod) {
-                /* module lookup requires matching the module */
-                if (!modname || strcmp(modname, mod))
+        if (mod_g) {
+                int mod_matches = (modname) ? ftrace_match(modname, mod_g) : 0;
+
+                /* blank module name to match all modules */
+                if (!mod_g->len) {
+                        /* blank module globbing: modname xor exclude_mod */
+                        if ((!exclude_mod) != (!modname))
+                                goto func_match;
+                        return 0;
+                }
+
+                /* not matching the module */
+                if (!modname || !mod_matches) {
+                        if (exclude_mod)
+                                goto func_match;
+                        else
+                                return 0;
+                }
+
+                if (mod_matches && exclude_mod)
                         return 0;
 
+func_match:
                 /* blank search means to match all funcs in the mod */
                 if (!func_g->len)
                         return 1;
@@ -3512,23 +3530,32 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
         struct ftrace_page *pg;
         struct dyn_ftrace *rec;
         struct ftrace_glob func_g = { .type = MATCH_FULL };
+        struct ftrace_glob mod_g = { .type = MATCH_FULL };
+        struct ftrace_glob *mod_match = (mod) ? &mod_g : NULL;
+        int exclude_mod = 0;
         int found = 0;
         int ret;
         int clear_filter;
 
-        if (len) {
+        if (func) {
                 func_g.type = filter_parse_regex(func, len, &func_g.search,
                                                  &clear_filter);
                 func_g.len = strlen(func_g.search);
         }
 
+        if (mod) {
+                mod_g.type = filter_parse_regex(mod, strlen(mod),
+                                &mod_g.search, &exclude_mod);
+                mod_g.len = strlen(mod_g.search);
+        }
+
         mutex_lock(&ftrace_lock);
 
         if (unlikely(ftrace_disabled))
                 goto out_unlock;
 
         do_for_each_ftrace_rec(pg, rec) {
-                if (ftrace_match_record(rec, mod, &func_g)) {
+                if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
                         ret = enter_record(hash, rec, clear_filter);
                         if (ret < 0) {
                                 found = ret;
@@ -3568,17 +3595,11 @@ ftrace_mod_callback(struct ftrace_hash *hash,
          * you can tell which command was used by the cmd
          * parameter.
          */
-
-        /* we must have a module name */
-        if (!module || !strlen(module))
-                return -EINVAL;
-
         ret = match_records(hash, func, strlen(func), module);
         if (!ret)
                 return -EINVAL;
         if (ret < 0)
                 return ret;
-
         return 0;
 }
 
@@ -3729,7 +3750,7 @@ register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 
         do_for_each_ftrace_rec(pg, rec) {
 
-                if (!ftrace_match_record(rec, NULL, &func_g))
+                if (!ftrace_match_record(rec, &func_g, NULL, 0))
                         continue;
 
                 entry = kmalloc(sizeof(*entry), GFP_KERNEL);
@@ -4621,7 +4642,7 @@ ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer)
 
         do_for_each_ftrace_rec(pg, rec) {
 
-                if (ftrace_match_record(rec, NULL, &func_g)) {
+                if (ftrace_match_record(rec, &func_g, NULL, 0)) {
                         /* if it is in the array */
                         exists = false;
                         for (i = 0; i < *idx; i++) {