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ftrace: show selected functions in set_ftrace_filter

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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: Steven Rostedt <srostedt@redhat.com>
This commit is contained in:
Steven Rostedt 2009-02-16 15:28:00 -05:00
parent 23b4ff3aa4
commit 8fc0c701c5
1 changed files with 103 additions and 20 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

123
kernel/trace/ftrace.c
View file

@ -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)
{