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ftrace: Replace FTRACE_FL_NOTRACE flag with a hash of ignored functions
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To prepare for the accounting system that will allow multiple users of
the function tracer, having the FTRACE_FL_NOTRACE as a flag in the
dyn_trace record does not make sense.

All ftrace_ops will soon have a hash of functions they should trace
and not trace. By making a global hash of functions not to trace makes
this easier for the transition.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Steven Rostedt authored and Steven Rostedt committed May 18, 2011
1 parent 9469234 commit b448c4e
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Showing 2 changed files with 150 additions and 27 deletions.
1 change: 0 additions & 1 deletion include/linux/ftrace.h
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Original file line number Diff line number Diff line change
Expand Up @@ -149,7 +149,6 @@ enum {
FTRACE_FL_FREE = (1 << 0),
FTRACE_FL_FILTER = (1 << 1),
FTRACE_FL_ENABLED = (1 << 2),
FTRACE_FL_NOTRACE = (1 << 3),
};

struct dyn_ftrace {
Expand Down
176 changes: 150 additions & 26 deletions kernel/trace/ftrace.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@
/* hash bits for specific function selection */
#define FTRACE_HASH_BITS 7
#define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)
#define FTRACE_HASH_MAX_BITS 10

/* ftrace_enabled is a method to turn ftrace on or off */
int ftrace_enabled __read_mostly;
Expand Down Expand Up @@ -865,6 +866,22 @@ enum {
FTRACE_START_FUNC_RET = (1 << 3),
FTRACE_STOP_FUNC_RET = (1 << 4),
};
struct ftrace_func_entry {
struct hlist_node hlist;
unsigned long ip;
};

struct ftrace_hash {
unsigned long size_bits;
struct hlist_head *buckets;
unsigned long count;
};

static struct hlist_head notrace_buckets[1 << FTRACE_HASH_MAX_BITS];
static struct ftrace_hash notrace_hash = {
.size_bits = FTRACE_HASH_MAX_BITS,
.buckets = notrace_buckets,
};

static int ftrace_filtered;

Expand All @@ -889,6 +906,79 @@ static struct ftrace_page *ftrace_pages;

static struct dyn_ftrace *ftrace_free_records;

static struct ftrace_func_entry *
ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
{
unsigned long key;
struct ftrace_func_entry *entry;
struct hlist_head *hhd;
struct hlist_node *n;

if (!hash->count)
return NULL;

if (hash->size_bits > 0)
key = hash_long(ip, hash->size_bits);
else
key = 0;

hhd = &hash->buckets[key];

hlist_for_each_entry_rcu(entry, n, hhd, hlist) {
if (entry->ip == ip)
return entry;
}
return NULL;
}

static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip)
{
struct ftrace_func_entry *entry;
struct hlist_head *hhd;
unsigned long key;

entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
return -ENOMEM;

if (hash->size_bits)
key = hash_long(ip, hash->size_bits);
else
key = 0;

entry->ip = ip;
hhd = &hash->buckets[key];
hlist_add_head(&entry->hlist, hhd);
hash->count++;

return 0;
}

static void
remove_hash_entry(struct ftrace_hash *hash,
struct ftrace_func_entry *entry)
{
hlist_del(&entry->hlist);
kfree(entry);
hash->count--;
}

static void ftrace_hash_clear(struct ftrace_hash *hash)
{
struct hlist_head *hhd;
struct hlist_node *tp, *tn;
struct ftrace_func_entry *entry;
int size = 1 << hash->size_bits;
int i;

for (i = 0; i < size; i++) {
hhd = &hash->buckets[i];
hlist_for_each_entry_safe(entry, tp, tn, hhd, hlist)
remove_hash_entry(hash, entry);
}
FTRACE_WARN_ON(hash->count);
}

/*
* This is a double for. Do not use 'break' to break out of the loop,
* you must use a goto.
Expand Down Expand Up @@ -1032,7 +1122,7 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
* If we want to enable it and filtering is on, enable it only if
* it's filtered
*/
if (enable && !(rec->flags & FTRACE_FL_NOTRACE)) {
if (enable && !ftrace_lookup_ip(&notrace_hash, rec->ip)) {
if (!ftrace_filtered || (rec->flags & FTRACE_FL_FILTER))
flag = FTRACE_FL_ENABLED;
}
Expand Down Expand Up @@ -1465,7 +1555,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
!(rec->flags & FTRACE_FL_FILTER)) ||

((iter->flags & FTRACE_ITER_NOTRACE) &&
!(rec->flags & FTRACE_FL_NOTRACE))) {
!ftrace_lookup_ip(&notrace_hash, rec->ip))) {
rec = NULL;
goto retry;
}
Expand Down Expand Up @@ -1609,14 +1699,15 @@ static void ftrace_filter_reset(int enable)
{
struct ftrace_page *pg;
struct dyn_ftrace *rec;
unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;

mutex_lock(&ftrace_lock);
if (enable)
if (enable) {
ftrace_filtered = 0;
do_for_each_ftrace_rec(pg, rec) {
rec->flags &= ~type;
} while_for_each_ftrace_rec();
do_for_each_ftrace_rec(pg, rec) {
rec->flags &= ~FTRACE_FL_FILTER;
} while_for_each_ftrace_rec();
} else
ftrace_hash_clear(&notrace_hash);
mutex_unlock(&ftrace_lock);
}

Expand Down Expand Up @@ -1716,13 +1807,36 @@ static int ftrace_match(char *str, char *regex, int len, int type)
return matched;
}

static void
update_record(struct dyn_ftrace *rec, unsigned long flag, int not)
static int
update_record(struct dyn_ftrace *rec, int enable, int not)
{
if (not)
rec->flags &= ~flag;
else
rec->flags |= flag;
struct ftrace_func_entry *entry;
struct ftrace_hash *hash = &notrace_hash;
int ret = 0;

if (enable) {
if (not)
rec->flags &= ~FTRACE_FL_FILTER;
else
rec->flags |= FTRACE_FL_FILTER;
} else {
if (not) {
/* Do nothing if it doesn't exist */
entry = ftrace_lookup_ip(hash, rec->ip);
if (!entry)
return 0;

remove_hash_entry(hash, entry);
} else {
/* Do nothing if it exists */
entry = ftrace_lookup_ip(hash, rec->ip);
if (entry)
return 0;

ret = add_hash_entry(hash, rec->ip);
}
}
return ret;
}

static int
Expand Down Expand Up @@ -1754,16 +1868,14 @@ static int match_records(char *buff, int len, char *mod, int enable, int not)
struct dyn_ftrace *rec;
int type = MATCH_FULL;
char *search = buff;
unsigned long flag;
int found = 0;
int ret;

if (len) {
type = filter_parse_regex(buff, len, &search, &not);
search_len = strlen(search);
}

flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;

mutex_lock(&ftrace_lock);

if (unlikely(ftrace_disabled))
Expand All @@ -1772,7 +1884,11 @@ static int match_records(char *buff, int len, char *mod, int enable, int not)
do_for_each_ftrace_rec(pg, rec) {

if (ftrace_match_record(rec, mod, search, search_len, type)) {
update_record(rec, flag, not);
ret = update_record(rec, enable, not);
if (ret < 0) {
found = ret;
goto out_unlock;
}
found = 1;
}
/*
Expand Down Expand Up @@ -1821,6 +1937,7 @@ static int
ftrace_mod_callback(char *func, char *cmd, char *param, int enable)
{
char *mod;
int ret = -EINVAL;

/*
* cmd == 'mod' because we only registered this func
Expand All @@ -1832,15 +1949,19 @@ ftrace_mod_callback(char *func, char *cmd, char *param, int enable)

/* we must have a module name */
if (!param)
return -EINVAL;
return ret;

mod = strsep(&param, ":");
if (!strlen(mod))
return -EINVAL;
return ret;

if (ftrace_match_module_records(func, mod, enable))
return 0;
return -EINVAL;
ret = ftrace_match_module_records(func, mod, enable);
if (!ret)
ret = -EINVAL;
if (ret < 0)
return ret;

return 0;
}

static struct ftrace_func_command ftrace_mod_cmd = {
Expand Down Expand Up @@ -2132,14 +2253,17 @@ static int ftrace_process_regex(char *buff, int len, int enable)
{
char *func, *command, *next = buff;
struct ftrace_func_command *p;
int ret = -EINVAL;
int ret;

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

if (!next) {
if (ftrace_match_records(func, len, enable))
return 0;
return ret;
ret = ftrace_match_records(func, len, enable);
if (!ret)
ret = -EINVAL;
if (ret < 0)
return ret;
return 0;
}

/* command found */
Expand Down

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