diff options
Diffstat (limited to 'kernel/tracepoint.c')
| -rw-r--r-- | kernel/tracepoint.c | 169 |
1 files changed, 147 insertions, 22 deletions
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index b219f1449c54..db110b8ae030 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -34,11 +34,16 @@ extern struct tracepoint * const __stop___tracepoints_ptrs[]; static const int tracepoint_debug; /* - * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the - * builtin and module tracepoints and the hash table. + * Tracepoints mutex protects the builtin and module tracepoints and the hash + * table, as well as the local module list. */ static DEFINE_MUTEX(tracepoints_mutex); +#ifdef CONFIG_MODULES +/* Local list of struct module */ +static LIST_HEAD(tracepoint_module_list); +#endif /* CONFIG_MODULES */ + /* * Tracepoint hash table, containing the active tracepoints. * Protected by tracepoints_mutex. @@ -292,9 +297,10 @@ static void disable_tracepoint(struct tracepoint *elem) * @end: end of the range * * Updates the probe callback corresponding to a range of tracepoints. + * Called with tracepoints_mutex held. */ -void tracepoint_update_probe_range(struct tracepoint * const *begin, - struct tracepoint * const *end) +static void tracepoint_update_probe_range(struct tracepoint * const *begin, + struct tracepoint * const *end) { struct tracepoint * const *iter; struct tracepoint_entry *mark_entry; @@ -302,7 +308,6 @@ void tracepoint_update_probe_range(struct tracepoint * const *begin, if (!begin) return; - mutex_lock(&tracepoints_mutex); for (iter = begin; iter < end; iter++) { mark_entry = get_tracepoint((*iter)->name); if (mark_entry) { @@ -312,11 +317,27 @@ void tracepoint_update_probe_range(struct tracepoint * const *begin, disable_tracepoint(*iter); } } - mutex_unlock(&tracepoints_mutex); } +#ifdef CONFIG_MODULES +void module_update_tracepoints(void) +{ + struct tp_module *tp_mod; + + list_for_each_entry(tp_mod, &tracepoint_module_list, list) + tracepoint_update_probe_range(tp_mod->tracepoints_ptrs, + tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints); +} +#else /* CONFIG_MODULES */ +void module_update_tracepoints(void) +{ +} +#endif /* CONFIG_MODULES */ + + /* * Update probes, removing the faulty probes. + * Called with tracepoints_mutex held. */ static void tracepoint_update_probes(void) { @@ -359,11 +380,12 @@ int tracepoint_probe_register(const char *name, void *probe, void *data) mutex_lock(&tracepoints_mutex); old = tracepoint_add_probe(name, probe, data); - mutex_unlock(&tracepoints_mutex); - if (IS_ERR(old)) + if (IS_ERR(old)) { + mutex_unlock(&tracepoints_mutex); return PTR_ERR(old); - + } tracepoint_update_probes(); /* may update entry */ + mutex_unlock(&tracepoints_mutex); release_probes(old); return 0; } @@ -402,11 +424,12 @@ int tracepoint_probe_unregister(const char *name, void *probe, void *data) mutex_lock(&tracepoints_mutex); old = tracepoint_remove_probe(name, probe, data); - mutex_unlock(&tracepoints_mutex); - if (IS_ERR(old)) + if (IS_ERR(old)) { + mutex_unlock(&tracepoints_mutex); return PTR_ERR(old); - + } tracepoint_update_probes(); /* may update entry */ + mutex_unlock(&tracepoints_mutex); release_probes(old); return 0; } @@ -489,9 +512,8 @@ void tracepoint_probe_update_all(void) if (!list_empty(&old_probes)) list_replace_init(&old_probes, &release_probes); need_update = 0; - mutex_unlock(&tracepoints_mutex); - tracepoint_update_probes(); + mutex_unlock(&tracepoints_mutex); list_for_each_entry_safe(pos, next, &release_probes, u.list) { list_del(&pos->u.list); call_rcu_sched(&pos->u.rcu, rcu_free_old_probes); @@ -509,7 +531,7 @@ EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); * Will return the first tracepoint in the range if the input tracepoint is * NULL. */ -int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, +static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, struct tracepoint * const *begin, struct tracepoint * const *end) { if (!*tracepoint && begin != end) { @@ -520,11 +542,12 @@ int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, return 1; return 0; } -EXPORT_SYMBOL_GPL(tracepoint_get_iter_range); +#ifdef CONFIG_MODULES static void tracepoint_get_iter(struct tracepoint_iter *iter) { int found = 0; + struct tp_module *iter_mod; /* Core kernel tracepoints */ if (!iter->module) { @@ -534,12 +557,43 @@ static void tracepoint_get_iter(struct tracepoint_iter *iter) if (found) goto end; } - /* tracepoints in modules. */ - found = module_get_iter_tracepoints(iter); + /* Tracepoints in modules */ + mutex_lock(&tracepoints_mutex); + list_for_each_entry(iter_mod, &tracepoint_module_list, list) { + /* + * Sorted module list + */ + if (iter_mod < iter->module) + continue; + else if (iter_mod > iter->module) + iter->tracepoint = NULL; + found = tracepoint_get_iter_range(&iter->tracepoint, + iter_mod->tracepoints_ptrs, + iter_mod->tracepoints_ptrs + + iter_mod->num_tracepoints); + if (found) { + iter->module = iter_mod; + break; + } + } + mutex_unlock(&tracepoints_mutex); end: if (!found) tracepoint_iter_reset(iter); } +#else /* CONFIG_MODULES */ +static void tracepoint_get_iter(struct tracepoint_iter *iter) +{ + int found = 0; + + /* Core kernel tracepoints */ + found = tracepoint_get_iter_range(&iter->tracepoint, + __start___tracepoints_ptrs, + __stop___tracepoints_ptrs); + if (!found) + tracepoint_iter_reset(iter); +} +#endif /* CONFIG_MODULES */ void tracepoint_iter_start(struct tracepoint_iter *iter) { @@ -566,26 +620,98 @@ EXPORT_SYMBOL_GPL(tracepoint_iter_stop); void tracepoint_iter_reset(struct tracepoint_iter *iter) { +#ifdef CONFIG_MODULES iter->module = NULL; +#endif /* CONFIG_MODULES */ iter->tracepoint = NULL; } EXPORT_SYMBOL_GPL(tracepoint_iter_reset); #ifdef CONFIG_MODULES +static int tracepoint_module_coming(struct module *mod) +{ + struct tp_module *tp_mod, *iter; + int ret = 0; + + /* + * We skip modules that tain the kernel, especially those with different + * module header (for forced load), to make sure we don't cause a crash. + */ + if (mod->taints) + return 0; + mutex_lock(&tracepoints_mutex); + tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); + if (!tp_mod) { + ret = -ENOMEM; + goto end; + } + tp_mod->num_tracepoints = mod->num_tracepoints; + tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs; + + /* + * tracepoint_module_list is kept sorted by struct module pointer + * address for iteration on tracepoints from a seq_file that can release + * the mutex between calls. + */ + list_for_each_entry_reverse(iter, &tracepoint_module_list, list) { + BUG_ON(iter == tp_mod); /* Should never be in the list twice */ + if (iter < tp_mod) { + /* We belong to the location right after iter. */ + list_add(&tp_mod->list, &iter->list); + goto module_added; + } + } + /* We belong to the beginning of the list */ + list_add(&tp_mod->list, &tracepoint_module_list); +module_added: + tracepoint_update_probe_range(mod->tracepoints_ptrs, + mod->tracepoints_ptrs + mod->num_tracepoints); +end: + mutex_unlock(&tracepoints_mutex); + return ret; +} + +static int tracepoint_module_going(struct module *mod) +{ + struct tp_module *pos; + + mutex_lock(&tracepoints_mutex); + tracepoint_update_probe_range(mod->tracepoints_ptrs, + mod->tracepoints_ptrs + mod->num_tracepoints); + list_for_each_entry(pos, &tracepoint_module_list, list) { + if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) { + list_del(&pos->list); + kfree(pos); + break; + } + } + /* + * In the case of modules that were tainted at "coming", we'll simply + * walk through the list without finding it. We cannot use the "tainted" + * flag on "going", in case a module taints the kernel only after being + * loaded. + */ + mutex_unlock(&tracepoints_mutex); + return 0; +} int tracepoint_module_notify(struct notifier_block *self, unsigned long val, void *data) { struct module *mod = data; + int ret = 0; switch (val) { case MODULE_STATE_COMING: + ret = tracepoint_module_coming(mod); + break; + case MODULE_STATE_LIVE: + break; case MODULE_STATE_GOING: - tracepoint_update_probe_range(mod->tracepoints_ptrs, - mod->tracepoints_ptrs + mod->num_tracepoints); + ret = tracepoint_module_going(mod); break; } - return 0; + return ret; } struct notifier_block tracepoint_module_nb = { @@ -598,7 +724,6 @@ static int init_tracepoints(void) return register_module_notifier(&tracepoint_module_nb); } __initcall(init_tracepoints); - #endif /* CONFIG_MODULES */ #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |