[PATCH 4/5] ftrace: add module globbing

[Dmitry Safonov]

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).

Signed-off-by: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
---
 kernel/trace/ftrace.c | 54 +++++++++++++++++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 17 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6ffc1a2..a2a4e57 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3480,19 +3480,37 @@ 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;
@@ -3507,23 +3525,31 @@ 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 found = 0;
 	int ret;
-	int clear_filter;
+	int clear_filter, exclude_mod = 0;
 
-	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;
@@ -3554,8 +3580,6 @@ static int
 ftrace_mod_callback(struct ftrace_hash *hash,
 		    char *func, char *cmd, char *module, int enable)
 {
-	int ret;
-
 	/*
 	 * cmd == 'mod' because we only registered this func
 	 * for the 'mod' ftrace_func_command.
@@ -3564,16 +3588,12 @@ ftrace_mod_callback(struct ftrace_hash *hash,
 	 * parameter.
 	 */
 
-	/* we must have a module name */
-	if (!module || !strlen(module))
-		return -EINVAL;
+	int ret = match_records(hash, func, strlen(func), module);
 
-	ret = match_records(hash, func, strlen(func), module);
 	if (ret == 0)
 		return -EINVAL;
 	if (ret < 0)
 		return ret;
-
 	return 0;
 }
 
@@ -3724,7 +3744,7 @@ 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);
@@ -4616,7 +4636,7 @@ 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++) {
-- 
2.5.3

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