[PATCH 13/15] ftrace: show selected functions in set_ftrace_filter

Steven Rostedt
2009-02-17T05:18:48Z

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[-- Type: text/plain, Size: 6398 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

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>
---
kernel/trace/ftrace.c | 123 +++++++++++++++++++++++++++++++++++++++++--------
1 files changed, 103 insertions(+), 20 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0b80e32..1e05884 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -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];
@@ -764,17 +781,86 @@ struct ftrace_iterator {
};

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)
{
--
1.5.6.5

--