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Commit 8fc0c701 authored by Steven Rostedt's avatar Steven Rostedt
Browse files

ftrace: show selected functions in set_ftrace_filter 



This patch adds output to show what functions have tracer hooks
attached to them.

  # echo 'sys_open:traceon:4' > /debug/tracing/set_ftrace_filter
  # cat set_ftrace_filter

 #### all functions enabled ####
 sys_open:ftrace_traceon:0000000000000004

  # echo 'do_fork:traceoff:' > set_ftrace_filter
  # cat set_ftrace_filter

 #### all functions enabled ####
 sys_open:ftrace_traceon:0000000000000002
 do_fork:ftrace_traceoff:ffffffffffffffff

Note the 4 changed to a 2. This is because The code was executed twice
since the traceoff was added. If a cat is done again:

 #### all functions enabled ####
 sys_open:ftrace_traceon
 do_fork:ftrace_traceoff:ffffffffffffffff

The number disappears. That is because it will not print a NULL.

Callbacks to allow the tracer to pretty print will be implemented soon.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent 23b4ff3a

kernel/trace/ftrace.c

+103 −20
Original line number Diff line number Diff line
@@ -45,14 +45,14 @@ 
			ftrace_kill();		\

	} while (0)



/* hash bits for specific function selection */

#define FTRACE_HASH_BITS 7

#define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)



/* ftrace_enabled is a method to turn ftrace on or off */

int ftrace_enabled __read_mostly;

static int last_ftrace_enabled;



/* set when tracing only a pid */

struct pid *ftrace_pid_trace;

static struct pid * const ftrace_swapper_pid = &init_struct_pid;



/* Quick disabling of function tracer. */

int function_trace_stop;
@@ -248,6 +248,21 @@ static void ftrace_update_pid_func(void) 
# error Dynamic ftrace depends on MCOUNT_RECORD

#endif



/* set when tracing only a pid */

struct pid *ftrace_pid_trace;

static struct pid * const ftrace_swapper_pid = &init_struct_pid;

static struct hlist_head ftrace_func_hash[FTRACE_FUNC_HASHSIZE] __read_mostly;



struct ftrace_func_hook {

	struct hlist_node	node;

	struct ftrace_hook_ops	*ops;

	unsigned long		flags;

	unsigned long		ip;

	void			*data;

	struct rcu_head		rcu;

};





enum {

	FTRACE_ENABLE_CALLS		= (1 << 0),

	FTRACE_DISABLE_CALLS		= (1 << 1),
@@ -750,12 +765,14 @@ enum { 
	FTRACE_ITER_NOTRACE	= (1 << 2),

	FTRACE_ITER_FAILURES	= (1 << 3),

	FTRACE_ITER_PRINTALL	= (1 << 4),

	FTRACE_ITER_HASH	= (1 << 5),

};



#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */



struct ftrace_iterator {

	struct ftrace_page	*pg;

	int			hidx;

	int			idx;

	unsigned		flags;

	unsigned char		buffer[FTRACE_BUFF_MAX+1];
@@ -763,18 +780,87 @@ struct ftrace_iterator { 
	unsigned		filtered;

};



static void *

t_hash_next(struct seq_file *m, void *v, loff_t *pos)

{

	struct ftrace_iterator *iter = m->private;

	struct hlist_node *hnd = v;

	struct hlist_head *hhd;



	WARN_ON(!(iter->flags & FTRACE_ITER_HASH));



	(*pos)++;



 retry:

	if (iter->hidx >= FTRACE_FUNC_HASHSIZE)

		return NULL;



	hhd = &ftrace_func_hash[iter->hidx];



	if (hlist_empty(hhd)) {

		iter->hidx++;

		hnd = NULL;

		goto retry;

	}



	if (!hnd)

		hnd = hhd->first;

	else {

		hnd = hnd->next;

		if (!hnd) {

			iter->hidx++;

			goto retry;

		}

	}



	return hnd;

}



static void *t_hash_start(struct seq_file *m, loff_t *pos)

{

	struct ftrace_iterator *iter = m->private;

	void *p = NULL;



	iter->flags |= FTRACE_ITER_HASH;



	return t_hash_next(m, p, pos);

}



static int t_hash_show(struct seq_file *m, void *v)

{

	struct ftrace_func_hook *rec;

	struct hlist_node *hnd = v;

	char str[KSYM_SYMBOL_LEN];



	rec = hlist_entry(hnd, struct ftrace_func_hook, node);



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

	seq_printf(m, "%s:", str);



	kallsyms_lookup((unsigned long)rec->ops->func, NULL, NULL, NULL, str);

	seq_printf(m, "%s", str);



	if (rec->data)

		seq_printf(m, ":%p", rec->data);

	seq_putc(m, '\n');



	return 0;

}



static void *

t_next(struct seq_file *m, void *v, loff_t *pos)

{

	struct ftrace_iterator *iter = m->private;

	struct dyn_ftrace *rec = NULL;



	if (iter->flags & FTRACE_ITER_HASH)

		return t_hash_next(m, v, pos);



	(*pos)++;



	if (iter->flags & FTRACE_ITER_PRINTALL)

		return NULL;



	mutex_lock(&ftrace_lock);

 retry:

	if (iter->idx >= iter->pg->index) {

		if (iter->pg->next) {
@@ -803,7 +889,6 @@ t_next(struct seq_file *m, void *v, loff_t *pos) 
			goto retry;

		}

	}

	mutex_unlock(&ftrace_lock);



	return rec;

}
@@ -813,6 +898,7 @@ static void *t_start(struct seq_file *m, loff_t *pos) 
	struct ftrace_iterator *iter = m->private;

	void *p = NULL;



	mutex_lock(&ftrace_lock);

	/*

	 * For set_ftrace_filter reading, if we have the filter

	 * off, we can short cut and just print out that all
@@ -820,12 +906,15 @@ static void *t_start(struct seq_file *m, loff_t *pos) 
	 */

	if (iter->flags & FTRACE_ITER_FILTER && !ftrace_filtered) {

		if (*pos > 0)

			return NULL;

			return t_hash_start(m, pos);

		iter->flags |= FTRACE_ITER_PRINTALL;

		(*pos)++;

		return iter;

	}



	if (iter->flags & FTRACE_ITER_HASH)

		return t_hash_start(m, pos);



	if (*pos > 0) {

		if (iter->idx < 0)

			return p;
@@ -835,11 +924,15 @@ static void *t_start(struct seq_file *m, loff_t *pos) 


	p = t_next(m, p, pos);



	if (!p)

		return t_hash_start(m, pos);



	return p;

}



static void t_stop(struct seq_file *m, void *p)

{

	mutex_unlock(&ftrace_lock);

}



static int t_show(struct seq_file *m, void *v)
@@ -848,6 +941,9 @@ static int t_show(struct seq_file *m, void *v) 
	struct dyn_ftrace *rec = v;

	char str[KSYM_SYMBOL_LEN];



	if (iter->flags & FTRACE_ITER_HASH)

		return t_hash_show(m, v);



	if (iter->flags & FTRACE_ITER_PRINTALL) {

		seq_printf(m, "#### all functions enabled ####\n");

		return 0;
@@ -1246,19 +1342,6 @@ static int __init ftrace_mod_cmd_init(void) 
}

device_initcall(ftrace_mod_cmd_init);



#define FTRACE_HASH_BITS 7

#define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)

static struct hlist_head ftrace_func_hash[FTRACE_FUNC_HASHSIZE] __read_mostly;



struct ftrace_func_hook {

	struct hlist_node	node;

	struct ftrace_hook_ops	*ops;

	unsigned long		flags;

	unsigned long		ip;

	void			*data;

	struct rcu_head		rcu;

};



static void

function_trace_hook_call(unsigned long ip, unsigned long parent_ip)

{