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Commit 64e7c440 authored by Steven Rostedt's avatar Steven Rostedt
Browse files

ftrace: add module command function filter selection 



This patch adds a "command" syntax to the function filtering files:

  /debugfs/tracing/set_ftrace_filter
  /debugfs/tracing/set_ftrace_notrace

Of the format:  <function>:<command>:<parameter>

The command is optional, and dependent on the command, so are
the parameters.

 echo do_fork > set_ftrace_filter

Will only trace 'do_fork'.

 echo 'sched_*' > set_ftrace_filter

Will only trace functions starting with the letters 'sched_'.

 echo '*:mod:ext3' > set_ftrace_filter

Will trace only the ext3 module functions.

 echo '*write*:mod:ext3' > set_ftrace_notrace

Will prevent the ext3 functions with the letters 'write' in
the name from being traced.

 echo '!*_allocate:mod:ext3' > set_ftrace_filter

Will remove the functions in ext3 that end with the letters
'_allocate' from the ftrace filter.

Although this patch implements the 'command' format, only the
'mod' command is supported. More commands to follow.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent 9f4801e3

kernel/trace/ftrace.c

+109 −6
Original line number Diff line number Diff line
@@ -1067,7 +1067,7 @@ enum { 
 *     0 otherwise.

 */

static int

ftrace_setup_glob(unsigned char *buff, int len, char **search, int *not)

ftrace_setup_glob(char *buff, int len, char **search, int *not)

{

	int type = MATCH_FULL;

	int i;
@@ -1100,14 +1100,11 @@ ftrace_setup_glob(unsigned char *buff, int len, char **search, int *not) 
	return type;

}



static int

ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)

static int ftrace_match(char *str, char *regex, int len, int type)

{

	char str[KSYM_SYMBOL_LEN];

	int matched = 0;

	char *ptr;



	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);

	switch (type) {

	case MATCH_FULL:

		if (strcmp(str, regex) == 0)
@@ -1131,6 +1128,15 @@ ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type) 
	return matched;

}



static int

ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)

{

	char str[KSYM_SYMBOL_LEN];



	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);

	return ftrace_match(str, regex, len, type);

}



static void ftrace_match_records(char *buff, int len, int enable)

{

	char *search;
@@ -1165,6 +1171,100 @@ static void ftrace_match_records(char *buff, int len, int enable) 
	spin_unlock(&ftrace_lock);

}



static int

ftrace_match_module_record(struct dyn_ftrace *rec, char *mod,

			   char *regex, int len, int type)

{

	char str[KSYM_SYMBOL_LEN];

	char *modname;



	kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);



	if (!modname || strcmp(modname, mod))

		return 0;



	/* blank search means to match all funcs in the mod */

	if (len)

		return ftrace_match(str, regex, len, type);

	else

		return 1;

}



static void ftrace_match_module_records(char *buff, char *mod, int enable)

{

	char *search = buff;

	struct ftrace_page *pg;

	struct dyn_ftrace *rec;

	int type = MATCH_FULL;

	unsigned long flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;

	unsigned search_len = 0;

	int not = 0;



	/* blank or '*' mean the same */

	if (strcmp(buff, "*") == 0)

		buff[0] = 0;



	/* handle the case of 'dont filter this module' */

	if (strcmp(buff, "!") == 0 || strcmp(buff, "!*") == 0) {

		buff[0] = 0;

		not = 1;

	}



	if (strlen(buff)) {

		type = ftrace_setup_glob(buff, strlen(buff), &search, &not);

		search_len = strlen(search);

	}



	/* should not be called from interrupt context */

	spin_lock(&ftrace_lock);

	if (enable)

		ftrace_filtered = 1;



	do_for_each_ftrace_rec(pg, rec) {



		if (rec->flags & FTRACE_FL_FAILED)

			continue;



		if (ftrace_match_module_record(rec, mod,

					       search, search_len, type)) {

			if (not)

				rec->flags &= ~flag;

			else

				rec->flags |= flag;

		}



	} while_for_each_ftrace_rec();

	spin_unlock(&ftrace_lock);

}



static int ftrace_process_regex(char *buff, int len, int enable)

{

	char *func, *mod, *command, *next = buff;



	func = strsep(&next, ":");



	if (!next) {

		ftrace_match_records(func, len, enable);

		return 0;

	}



	/* command fonud */



	command = strsep(&next, ":");



	if (strcmp(command, "mod") == 0) {

		/* only match modules */

		if (!next)

			return -EINVAL;



		mod = strsep(&next, ":");

		ftrace_match_module_records(func, mod, enable);

		return 0;

	}



	return -EINVAL;

}



static ssize_t

ftrace_regex_write(struct file *file, const char __user *ubuf,

		   size_t cnt, loff_t *ppos, int enable)
@@ -1232,7 +1332,10 @@ ftrace_regex_write(struct file *file, const char __user *ubuf, 
	if (isspace(ch)) {

		iter->filtered++;

		iter->buffer[iter->buffer_idx] = 0;

		ftrace_match_records(iter->buffer, iter->buffer_idx, enable);

		ret = ftrace_process_regex(iter->buffer,

					   iter->buffer_idx, enable);

		if (ret)

			goto out;

		iter->buffer_idx = 0;

	} else

		iter->flags |= FTRACE_ITER_CONT;