diff options
Diffstat (limited to 'kernel/trace/ftrace.c')
| -rw-r--r-- | kernel/trace/ftrace.c | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 157d4f68b0e..0b80e325f29 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -27,6 +27,7 @@ #include <linux/sysctl.h> #include <linux/ctype.h> #include <linux/list.h> +#include <linux/hash.h> #include <asm/ftrace.h> @@ -1245,6 +1246,252 @@ 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) +{ + struct ftrace_func_hook *entry; + struct hlist_head *hhd; + struct hlist_node *n; + unsigned long key; + int resched; + + key = hash_long(ip, FTRACE_HASH_BITS); + + hhd = &ftrace_func_hash[key]; + + if (hlist_empty(hhd)) + return; + + /* + * Disable preemption for these calls to prevent a RCU grace + * period. This syncs the hash iteration and freeing of items + * on the hash. rcu_read_lock is too dangerous here. + */ + resched = ftrace_preempt_disable(); + hlist_for_each_entry_rcu(entry, n, hhd, node) { + if (entry->ip == ip) + entry->ops->func(ip, parent_ip, &entry->data); + } + ftrace_preempt_enable(resched); +} + +static struct ftrace_ops trace_hook_ops __read_mostly = +{ + .func = function_trace_hook_call, +}; + +static int ftrace_hook_registered; + +static void __enable_ftrace_function_hook(void) +{ + int i; + + if (ftrace_hook_registered) + return; + + for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) { + struct hlist_head *hhd = &ftrace_func_hash[i]; + if (hhd->first) + break; + } + /* Nothing registered? */ + if (i == FTRACE_FUNC_HASHSIZE) + return; + + __register_ftrace_function(&trace_hook_ops); + ftrace_startup(0); + ftrace_hook_registered = 1; +} + +static void __disable_ftrace_function_hook(void) +{ + int i; + + if (!ftrace_hook_registered) + return; + + for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) { + struct hlist_head *hhd = &ftrace_func_hash[i]; + if (hhd->first) + return; + } + + /* no more funcs left */ + __unregister_ftrace_function(&trace_hook_ops); + ftrace_shutdown(0); + ftrace_hook_registered = 0; +} + + +static void ftrace_free_entry_rcu(struct rcu_head *rhp) +{ + struct ftrace_func_hook *entry = + container_of(rhp, struct ftrace_func_hook, rcu); + + if (entry->ops->free) + entry->ops->free(&entry->data); + kfree(entry); +} + + +int +register_ftrace_function_hook(char *glob, struct ftrace_hook_ops *ops, + void *data) +{ + struct ftrace_func_hook *entry; + struct ftrace_page *pg; + struct dyn_ftrace *rec; + unsigned long key; + int type, len, not; + int count = 0; + char *search; + + type = ftrace_setup_glob(glob, strlen(glob), &search, ¬); + len = strlen(search); + + /* we do not support '!' for function hooks */ + if (WARN_ON(not)) + return -EINVAL; + + mutex_lock(&ftrace_lock); + do_for_each_ftrace_rec(pg, rec) { + + if (rec->flags & FTRACE_FL_FAILED) + continue; + + if (!ftrace_match_record(rec, search, len, type)) + continue; + + entry = kmalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) { + /* If we did not hook to any, then return error */ + if (!count) + count = -ENOMEM; + goto out_unlock; + } + + count++; + + entry->data = data; + + /* + * The caller might want to do something special + * for each function we find. We call the callback + * to give the caller an opportunity to do so. + */ + if (ops->callback) { + if (ops->callback(rec->ip, &entry->data) < 0) { + /* caller does not like this func */ + kfree(entry); + continue; + } + } + + entry->ops = ops; + entry->ip = rec->ip; + + key = hash_long(entry->ip, FTRACE_HASH_BITS); + hlist_add_head_rcu(&entry->node, &ftrace_func_hash[key]); + + } while_for_each_ftrace_rec(); + __enable_ftrace_function_hook(); + + out_unlock: + mutex_unlock(&ftrace_lock); + + return count; +} + +enum { + HOOK_TEST_FUNC = 1, + HOOK_TEST_DATA = 2 +}; + +static void +__unregister_ftrace_function_hook(char *glob, struct ftrace_hook_ops *ops, + void *data, int flags) +{ + struct ftrace_func_hook *entry; + struct hlist_node *n, *tmp; + char str[KSYM_SYMBOL_LEN]; + int type = MATCH_FULL; + int i, len = 0; + char *search; + + if (glob && (strcmp(glob, "*") || !strlen(glob))) + glob = NULL; + else { + int not; + + type = ftrace_setup_glob(glob, strlen(glob), &search, ¬); + len = strlen(search); + + /* we do not support '!' for function hooks */ + if (WARN_ON(not)) + return; + } + + mutex_lock(&ftrace_lock); + for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) { + struct hlist_head *hhd = &ftrace_func_hash[i]; + + hlist_for_each_entry_safe(entry, n, tmp, hhd, node) { + + /* break up if statements for readability */ + if ((flags & HOOK_TEST_FUNC) && entry->ops != ops) + continue; + + if ((flags & HOOK_TEST_DATA) && entry->data != data) + continue; + + /* do this last, since it is the most expensive */ + if (glob) { + kallsyms_lookup(entry->ip, NULL, NULL, + NULL, str); + if (!ftrace_match(str, glob, len, type)) + continue; + } + + hlist_del(&entry->node); + call_rcu(&entry->rcu, ftrace_free_entry_rcu); + } + } + __disable_ftrace_function_hook(); + mutex_unlock(&ftrace_lock); +} + +void +unregister_ftrace_function_hook(char *glob, struct ftrace_hook_ops *ops, + void *data) +{ + __unregister_ftrace_function_hook(glob, ops, data, + HOOK_TEST_FUNC | HOOK_TEST_DATA); +} + +void +unregister_ftrace_function_hook_func(char *glob, struct ftrace_hook_ops *ops) +{ + __unregister_ftrace_function_hook(glob, ops, NULL, HOOK_TEST_FUNC); +} + +void unregister_ftrace_function_hook_all(char *glob) +{ + __unregister_ftrace_function_hook(glob, NULL, NULL, 0); +} + static LIST_HEAD(ftrace_commands); static DEFINE_MUTEX(ftrace_cmd_mutex); |