diff options
Diffstat (limited to 'kernel/tracepoint.c')
| -rw-r--r-- | kernel/tracepoint.c | 1033 |
1 files changed, 523 insertions, 510 deletions
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 29f26540e9c9..62719d2941c9 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -1,19 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-or-later /* - * Copyright (C) 2008 Mathieu Desnoyers - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * Copyright (C) 2008-2014 Mathieu Desnoyers */ #include <linux/module.h> #include <linux/mutex.h> @@ -24,139 +11,196 @@ #include <linux/tracepoint.h> #include <linux/err.h> #include <linux/slab.h> -#include <linux/sched.h> +#include <linux/sched/signal.h> +#include <linux/sched/task.h> #include <linux/static_key.h> -extern struct tracepoint * const __start___tracepoints_ptrs[]; -extern struct tracepoint * const __stop___tracepoints_ptrs[]; +enum tp_func_state { + TP_FUNC_0, + TP_FUNC_1, + TP_FUNC_2, + TP_FUNC_N, +}; + +extern tracepoint_ptr_t __start___tracepoints_ptrs[]; +extern tracepoint_ptr_t __stop___tracepoints_ptrs[]; + +enum tp_transition_sync { + TP_TRANSITION_SYNC_1_0_1, + TP_TRANSITION_SYNC_N_2_1, + + _NR_TP_TRANSITION_SYNC, +}; + +struct tp_transition_snapshot { + unsigned long rcu; + bool ongoing; +}; + +/* Protected by tracepoints_mutex */ +static struct tp_transition_snapshot tp_transition_snapshot[_NR_TP_TRANSITION_SYNC]; + +static void tp_rcu_get_state(enum tp_transition_sync sync) +{ + struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync]; + + /* Keep the latest get_state snapshot. */ + snapshot->rcu = get_state_synchronize_rcu(); + snapshot->ongoing = true; +} + +static void tp_rcu_cond_sync(enum tp_transition_sync sync) +{ + struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync]; + + if (!snapshot->ongoing) + return; + cond_synchronize_rcu(snapshot->rcu); + snapshot->ongoing = false; +} /* Set to 1 to enable tracepoint debug output */ static const int tracepoint_debug; +#ifdef CONFIG_MODULES /* - * Tracepoints mutex protects the builtin and module tracepoints and the hash - * table, as well as the local module list. + * Tracepoint module list mutex protects the local module list. */ -static DEFINE_MUTEX(tracepoints_mutex); +static DEFINE_MUTEX(tracepoint_module_list_mutex); -#ifdef CONFIG_MODULES -/* Local list of struct module */ +/* Local list of struct tp_module */ static LIST_HEAD(tracepoint_module_list); #endif /* CONFIG_MODULES */ /* - * Tracepoint hash table, containing the active tracepoints. - * Protected by tracepoints_mutex. + * tracepoints_mutex protects the builtin and module tracepoints. + * tracepoints_mutex nests inside tracepoint_module_list_mutex. */ -#define TRACEPOINT_HASH_BITS 6 -#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS) -static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; +static DEFINE_MUTEX(tracepoints_mutex); /* * Note about RCU : * It is used to delay the free of multiple probes array until a quiescent * state is reached. - * Tracepoint entries modifications are protected by the tracepoints_mutex. */ -struct tracepoint_entry { - struct hlist_node hlist; - struct tracepoint_func *funcs; - int refcount; /* Number of times armed. 0 if disarmed. */ - char name[0]; -}; - struct tp_probes { - union { - struct rcu_head rcu; - struct list_head list; - } u; - struct tracepoint_func probes[0]; + struct rcu_head rcu; + struct tracepoint_func probes[]; }; +/* Called in removal of a func but failed to allocate a new tp_funcs */ +static void tp_stub_func(void) +{ + return; +} + static inline void *allocate_probes(int count) { - struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) - + sizeof(struct tp_probes), GFP_KERNEL); + struct tp_probes *p = kmalloc(struct_size(p, probes, count), + GFP_KERNEL); return p == NULL ? NULL : p->probes; } static void rcu_free_old_probes(struct rcu_head *head) { - kfree(container_of(head, struct tp_probes, u.rcu)); + kfree(container_of(head, struct tp_probes, rcu)); } -static inline void release_probes(struct tracepoint_func *old) +static inline void release_probes(struct tracepoint *tp, struct tracepoint_func *old) { if (old) { struct tp_probes *tp_probes = container_of(old, struct tp_probes, probes[0]); - call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes); + + if (tracepoint_is_faultable(tp)) + call_rcu_tasks_trace(&tp_probes->rcu, rcu_free_old_probes); + else + call_rcu(&tp_probes->rcu, rcu_free_old_probes); } } -static void debug_print_probes(struct tracepoint_entry *entry) +static void debug_print_probes(struct tracepoint_func *funcs) { int i; - if (!tracepoint_debug || !entry->funcs) + if (!tracepoint_debug || !funcs) return; - for (i = 0; entry->funcs[i].func; i++) - printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func); + for (i = 0; funcs[i].func; i++) + printk(KERN_DEBUG "Probe %d : %pSb\n", i, funcs[i].func); } static struct tracepoint_func * -tracepoint_entry_add_probe(struct tracepoint_entry *entry, - void *probe, void *data) +func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func, + int prio) { - int nr_probes = 0; struct tracepoint_func *old, *new; + int iter_probes; /* Iterate over old probe array. */ + int nr_probes = 0; /* Counter for probes */ + int pos = -1; /* Insertion position into new array */ - if (WARN_ON(!probe)) + if (WARN_ON(!tp_func->func)) return ERR_PTR(-EINVAL); - debug_print_probes(entry); - old = entry->funcs; + debug_print_probes(*funcs); + old = *funcs; if (old) { /* (N -> N+1), (N != 0, 1) probes */ - for (nr_probes = 0; old[nr_probes].func; nr_probes++) - if (old[nr_probes].func == probe && - old[nr_probes].data == data) + for (iter_probes = 0; old[iter_probes].func; iter_probes++) { + if (old[iter_probes].func == tp_stub_func) + continue; /* Skip stub functions. */ + if (old[iter_probes].func == tp_func->func && + old[iter_probes].data == tp_func->data) return ERR_PTR(-EEXIST); + nr_probes++; + } } /* + 2 : one for new probe, one for NULL func */ new = allocate_probes(nr_probes + 2); if (new == NULL) return ERR_PTR(-ENOMEM); - if (old) - memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); - new[nr_probes].func = probe; - new[nr_probes].data = data; - new[nr_probes + 1].func = NULL; - entry->refcount = nr_probes + 1; - entry->funcs = new; - debug_print_probes(entry); + if (old) { + nr_probes = 0; + for (iter_probes = 0; old[iter_probes].func; iter_probes++) { + if (old[iter_probes].func == tp_stub_func) + continue; + /* Insert before probes of lower priority */ + if (pos < 0 && old[iter_probes].prio < prio) + pos = nr_probes++; + new[nr_probes++] = old[iter_probes]; + } + if (pos < 0) + pos = nr_probes++; + /* nr_probes now points to the end of the new array */ + } else { + pos = 0; + nr_probes = 1; /* must point at end of array */ + } + new[pos] = *tp_func; + new[nr_probes].func = NULL; + *funcs = new; + debug_print_probes(*funcs); return old; } -static void * -tracepoint_entry_remove_probe(struct tracepoint_entry *entry, - void *probe, void *data) +static void *func_remove(struct tracepoint_func **funcs, + struct tracepoint_func *tp_func) { int nr_probes = 0, nr_del = 0, i; struct tracepoint_func *old, *new; - old = entry->funcs; + old = *funcs; if (!old) return ERR_PTR(-ENOENT); - debug_print_probes(entry); + debug_print_probes(*funcs); /* (N -> M), (N > 1, M >= 0) probes */ - if (probe) { + if (tp_func->func) { for (nr_probes = 0; old[nr_probes].func; nr_probes++) { - if (old[nr_probes].func == probe && - old[nr_probes].data == data) + if ((old[nr_probes].func == tp_func->func && + old[nr_probes].data == tp_func->data) || + old[nr_probes].func == tp_stub_func) nr_del++; } } @@ -167,525 +211,434 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry, */ if (nr_probes - nr_del == 0) { /* N -> 0, (N > 1) */ - entry->funcs = NULL; - entry->refcount = 0; - debug_print_probes(entry); + *funcs = NULL; + debug_print_probes(*funcs); return old; } else { int j = 0; /* N -> M, (N > 1, M > 0) */ /* + 1 for NULL */ new = allocate_probes(nr_probes - nr_del + 1); - if (new == NULL) - return ERR_PTR(-ENOMEM); - for (i = 0; old[i].func; i++) - if (old[i].func != probe || old[i].data != data) - new[j++] = old[i]; - new[nr_probes - nr_del].func = NULL; - entry->refcount = nr_probes - nr_del; - entry->funcs = new; + if (new) { + for (i = 0; old[i].func; i++) { + if ((old[i].func != tp_func->func || + old[i].data != tp_func->data) && + old[i].func != tp_stub_func) + new[j++] = old[i]; + } + new[nr_probes - nr_del].func = NULL; + *funcs = new; + } else { + /* + * Failed to allocate, replace the old function + * with calls to tp_stub_func. + */ + for (i = 0; old[i].func; i++) { + if (old[i].func == tp_func->func && + old[i].data == tp_func->data) + WRITE_ONCE(old[i].func, tp_stub_func); + } + *funcs = old; + } } - debug_print_probes(entry); + debug_print_probes(*funcs); return old; } /* - * Get tracepoint if the tracepoint is present in the tracepoint hash table. - * Must be called with tracepoints_mutex held. - * Returns NULL if not present. + * Count the number of functions (enum tp_func_state) in a tp_funcs array. */ -static struct tracepoint_entry *get_tracepoint(const char *name) +static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs) { - struct hlist_head *head; - struct tracepoint_entry *e; - u32 hash = jhash(name, strlen(name), 0); - - head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; - hlist_for_each_entry(e, head, hlist) { - if (!strcmp(name, e->name)) - return e; - } - return NULL; + if (!tp_funcs) + return TP_FUNC_0; + if (!tp_funcs[1].func) + return TP_FUNC_1; + if (!tp_funcs[2].func) + return TP_FUNC_2; + return TP_FUNC_N; /* 3 or more */ } -/* - * Add the tracepoint to the tracepoint hash table. Must be called with - * tracepoints_mutex held. - */ -static struct tracepoint_entry *add_tracepoint(const char *name) +static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs) { - struct hlist_head *head; - struct tracepoint_entry *e; - size_t name_len = strlen(name) + 1; - u32 hash = jhash(name, name_len-1, 0); - - head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; - hlist_for_each_entry(e, head, hlist) { - if (!strcmp(name, e->name)) { - printk(KERN_NOTICE - "tracepoint %s busy\n", name); - return ERR_PTR(-EEXIST); /* Already there */ - } - } - /* - * Using kmalloc here to allocate a variable length element. Could - * cause some memory fragmentation if overused. - */ - e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); - if (!e) - return ERR_PTR(-ENOMEM); - memcpy(&e->name[0], name, name_len); - e->funcs = NULL; - e->refcount = 0; - hlist_add_head(&e->hlist, head); - return e; -} + void *func = tp->iterator; -/* - * Remove the tracepoint from the tracepoint hash table. Must be called with - * mutex_lock held. - */ -static inline void remove_tracepoint(struct tracepoint_entry *e) -{ - hlist_del(&e->hlist); - kfree(e); + /* Synthetic events do not have static call sites */ + if (!tp->static_call_key) + return; + if (nr_func_state(tp_funcs) == TP_FUNC_1) + func = tp_funcs[0].func; + __static_call_update(tp->static_call_key, tp->static_call_tramp, func); } /* - * Sets the probe callback corresponding to one tracepoint. + * Add the probe function to a tracepoint. */ -static void set_tracepoint(struct tracepoint_entry **entry, - struct tracepoint *elem, int active) +static int tracepoint_add_func(struct tracepoint *tp, + struct tracepoint_func *func, int prio, + bool warn) { - WARN_ON(strcmp((*entry)->name, elem->name) != 0); + struct tracepoint_func *old, *tp_funcs; + int ret; + + if (tp->ext && tp->ext->regfunc && !static_key_enabled(&tp->key)) { + ret = tp->ext->regfunc(); + if (ret < 0) + return ret; + } - if (elem->regfunc && !static_key_enabled(&elem->key) && active) - elem->regfunc(); - else if (elem->unregfunc && static_key_enabled(&elem->key) && !active) - elem->unregfunc(); + tp_funcs = rcu_dereference_protected(tp->funcs, + lockdep_is_held(&tracepoints_mutex)); + old = func_add(&tp_funcs, func, prio); + if (IS_ERR(old)) { + WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM); + return PTR_ERR(old); + } /* - * rcu_assign_pointer has a smp_wmb() which makes sure that the new - * probe callbacks array is consistent before setting a pointer to it. - * This array is referenced by __DO_TRACE from - * include/linux/tracepoints.h. A matching smp_read_barrier_depends() - * is used. + * rcu_assign_pointer has as smp_store_release() which makes sure + * that the new probe callbacks array is consistent before setting + * a pointer to it. This array is referenced by __DO_TRACE from + * include/linux/tracepoint.h using rcu_dereference_sched(). */ - rcu_assign_pointer(elem->funcs, (*entry)->funcs); - if (active && !static_key_enabled(&elem->key)) - static_key_slow_inc(&elem->key); - else if (!active && static_key_enabled(&elem->key)) - static_key_slow_dec(&elem->key); + switch (nr_func_state(tp_funcs)) { + case TP_FUNC_1: /* 0->1 */ + /* + * Make sure new static func never uses old data after a + * 1->0->1 transition sequence. + */ + tp_rcu_cond_sync(TP_TRANSITION_SYNC_1_0_1); + /* Set static call to first function */ + tracepoint_update_call(tp, tp_funcs); + /* Both iterator and static call handle NULL tp->funcs */ + rcu_assign_pointer(tp->funcs, tp_funcs); + static_branch_enable(&tp->key); + break; + case TP_FUNC_2: /* 1->2 */ + /* Set iterator static call */ + tracepoint_update_call(tp, tp_funcs); + /* + * Iterator callback installed before updating tp->funcs. + * Requires ordering between RCU assign/dereference and + * static call update/call. + */ + fallthrough; + case TP_FUNC_N: /* N->N+1 (N>1) */ + rcu_assign_pointer(tp->funcs, tp_funcs); + /* + * Make sure static func never uses incorrect data after a + * N->...->2->1 (N>1) transition sequence. + */ + if (tp_funcs[0].data != old[0].data) + tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1); + break; + default: + WARN_ON_ONCE(1); + break; + } + + release_probes(tp, old); + return 0; } /* - * Disable a tracepoint and its probe callback. + * Remove a probe function from a tracepoint. * Note: only waiting an RCU period after setting elem->call to the empty * function insures that the original callback is not used anymore. This insured * by preempt_disable around the call site. */ -static void disable_tracepoint(struct tracepoint *elem) +static int tracepoint_remove_func(struct tracepoint *tp, + struct tracepoint_func *func) { - if (elem->unregfunc && static_key_enabled(&elem->key)) - elem->unregfunc(); - - if (static_key_enabled(&elem->key)) - static_key_slow_dec(&elem->key); - rcu_assign_pointer(elem->funcs, NULL); -} - -/** - * tracepoint_update_probe_range - Update a probe range - * @begin: beginning of the range - * @end: end of the range - * - * Updates the probe callback corresponding to a range of tracepoints. - * Called with tracepoints_mutex held. - */ -static void tracepoint_update_probe_range(struct tracepoint * const *begin, - struct tracepoint * const *end) -{ - struct tracepoint * const *iter; - struct tracepoint_entry *mark_entry; - - if (!begin) - return; - - for (iter = begin; iter < end; iter++) { - mark_entry = get_tracepoint((*iter)->name); - if (mark_entry) { - set_tracepoint(&mark_entry, *iter, - !!mark_entry->refcount); - } else { - disable_tracepoint(*iter); - } - } -} - -#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 */ + struct tracepoint_func *old, *tp_funcs; + tp_funcs = rcu_dereference_protected(tp->funcs, + lockdep_is_held(&tracepoints_mutex)); + old = func_remove(&tp_funcs, func); + if (WARN_ON_ONCE(IS_ERR(old))) + return PTR_ERR(old); -/* - * Update probes, removing the faulty probes. - * Called with tracepoints_mutex held. - */ -static void tracepoint_update_probes(void) -{ - /* Core kernel tracepoints */ - tracepoint_update_probe_range(__start___tracepoints_ptrs, - __stop___tracepoints_ptrs); - /* tracepoints in modules. */ - module_update_tracepoints(); -} + if (tp_funcs == old) + /* Failed allocating new tp_funcs, replaced func with stub */ + return 0; -static struct tracepoint_func * -tracepoint_add_probe(const char *name, void *probe, void *data) -{ - struct tracepoint_entry *entry; - struct tracepoint_func *old; - - entry = get_tracepoint(name); - if (!entry) { - entry = add_tracepoint(name); - if (IS_ERR(entry)) - return (struct tracepoint_func *)entry; + switch (nr_func_state(tp_funcs)) { + case TP_FUNC_0: /* 1->0 */ + /* Removed last function */ + if (tp->ext && tp->ext->unregfunc && static_key_enabled(&tp->key)) + tp->ext->unregfunc(); + static_branch_disable(&tp->key); + /* Set iterator static call */ + tracepoint_update_call(tp, tp_funcs); + /* Both iterator and static call handle NULL tp->funcs */ + rcu_assign_pointer(tp->funcs, NULL); + /* + * Make sure new static func never uses old data after a + * 1->0->1 transition sequence. + */ + tp_rcu_get_state(TP_TRANSITION_SYNC_1_0_1); + break; + case TP_FUNC_1: /* 2->1 */ + rcu_assign_pointer(tp->funcs, tp_funcs); + /* + * Make sure static func never uses incorrect data after a + * N->...->2->1 (N>2) transition sequence. If the first + * element's data has changed, then force the synchronization + * to prevent current readers that have loaded the old data + * from calling the new function. + */ + if (tp_funcs[0].data != old[0].data) + tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1); + tp_rcu_cond_sync(TP_TRANSITION_SYNC_N_2_1); + /* Set static call to first function */ + tracepoint_update_call(tp, tp_funcs); + break; + case TP_FUNC_2: /* N->N-1 (N>2) */ + fallthrough; + case TP_FUNC_N: + rcu_assign_pointer(tp->funcs, tp_funcs); + /* + * Make sure static func never uses incorrect data after a + * N->...->2->1 (N>2) transition sequence. + */ + if (tp_funcs[0].data != old[0].data) + tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1); + break; + default: + WARN_ON_ONCE(1); + break; } - old = tracepoint_entry_add_probe(entry, probe, data); - if (IS_ERR(old) && !entry->refcount) - remove_tracepoint(entry); - return old; + release_probes(tp, old); + return 0; } /** - * tracepoint_probe_register - Connect a probe to a tracepoint - * @name: tracepoint name + * tracepoint_probe_register_prio_may_exist - Connect a probe to a tracepoint with priority + * @tp: tracepoint * @probe: probe handler + * @data: tracepoint data + * @prio: priority of this function over other registered functions * - * Returns 0 if ok, error value on error. - * The probe address must at least be aligned on the architecture pointer size. + * Same as tracepoint_probe_register_prio() except that it will not warn + * if the tracepoint is already registered. */ -int tracepoint_probe_register(const char *name, void *probe, void *data) +int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, + void *data, int prio) { - struct tracepoint_func *old; + struct tracepoint_func tp_func; + int ret; mutex_lock(&tracepoints_mutex); - old = tracepoint_add_probe(name, probe, data); - if (IS_ERR(old)) { - mutex_unlock(&tracepoints_mutex); - return PTR_ERR(old); - } - tracepoint_update_probes(); /* may update entry */ + tp_func.func = probe; + tp_func.data = data; + tp_func.prio = prio; + ret = tracepoint_add_func(tp, &tp_func, prio, false); mutex_unlock(&tracepoints_mutex); - release_probes(old); - return 0; -} -EXPORT_SYMBOL_GPL(tracepoint_probe_register); - -static struct tracepoint_func * -tracepoint_remove_probe(const char *name, void *probe, void *data) -{ - struct tracepoint_entry *entry; - struct tracepoint_func *old; - - entry = get_tracepoint(name); - if (!entry) - return ERR_PTR(-ENOENT); - old = tracepoint_entry_remove_probe(entry, probe, data); - if (IS_ERR(old)) - return old; - if (!entry->refcount) - remove_tracepoint(entry); - return old; + return ret; } +EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist); /** - * tracepoint_probe_unregister - Disconnect a probe from a tracepoint - * @name: tracepoint name - * @probe: probe function pointer + * tracepoint_probe_register_prio - Connect a probe to a tracepoint with priority + * @tp: tracepoint + * @probe: probe handler + * @data: tracepoint data + * @prio: priority of this function over other registered functions * - * We do not need to call a synchronize_sched to make sure the probes have - * finished running before doing a module unload, because the module unload - * itself uses stop_machine(), which insures that every preempt disabled section - * have finished. + * Returns 0 if ok, error value on error. + * Note: if @tp is within a module, the caller is responsible for + * unregistering the probe before the module is gone. This can be + * performed either with a tracepoint module going notifier, or from + * within module exit functions. */ -int tracepoint_probe_unregister(const char *name, void *probe, void *data) +int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, + void *data, int prio) { - struct tracepoint_func *old; + struct tracepoint_func tp_func; + int ret; mutex_lock(&tracepoints_mutex); - old = tracepoint_remove_probe(name, probe, data); - if (IS_ERR(old)) { - mutex_unlock(&tracepoints_mutex); - return PTR_ERR(old); - } - tracepoint_update_probes(); /* may update entry */ + tp_func.func = probe; + tp_func.data = data; + tp_func.prio = prio; + ret = tracepoint_add_func(tp, &tp_func, prio, true); mutex_unlock(&tracepoints_mutex); - release_probes(old); - return 0; -} -EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); - -static LIST_HEAD(old_probes); -static int need_update; - -static void tracepoint_add_old_probes(void *old) -{ - need_update = 1; - if (old) { - struct tp_probes *tp_probes = container_of(old, - struct tp_probes, probes[0]); - list_add(&tp_probes->u.list, &old_probes); - } + return ret; } +EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio); /** - * tracepoint_probe_register_noupdate - register a probe but not connect - * @name: tracepoint name + * tracepoint_probe_register - Connect a probe to a tracepoint + * @tp: tracepoint * @probe: probe handler + * @data: tracepoint data * - * caller must call tracepoint_probe_update_all() + * Returns 0 if ok, error value on error. + * Note: if @tp is within a module, the caller is responsible for + * unregistering the probe before the module is gone. This can be + * performed either with a tracepoint module going notifier, or from + * within module exit functions. */ -int tracepoint_probe_register_noupdate(const char *name, void *probe, - void *data) +int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data) { - struct tracepoint_func *old; - - mutex_lock(&tracepoints_mutex); - old = tracepoint_add_probe(name, probe, data); - if (IS_ERR(old)) { - mutex_unlock(&tracepoints_mutex); - return PTR_ERR(old); - } - tracepoint_add_old_probes(old); - mutex_unlock(&tracepoints_mutex); - return 0; + return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO); } -EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate); +EXPORT_SYMBOL_GPL(tracepoint_probe_register); /** - * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect - * @name: tracepoint name + * tracepoint_probe_unregister - Disconnect a probe from a tracepoint + * @tp: tracepoint * @probe: probe function pointer + * @data: tracepoint data * - * caller must call tracepoint_probe_update_all() + * Returns 0 if ok, error value on error. */ -int tracepoint_probe_unregister_noupdate(const char *name, void *probe, - void *data) +int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data) { - struct tracepoint_func *old; + struct tracepoint_func tp_func; + int ret; mutex_lock(&tracepoints_mutex); - old = tracepoint_remove_probe(name, probe, data); - if (IS_ERR(old)) { - mutex_unlock(&tracepoints_mutex); - return PTR_ERR(old); - } - tracepoint_add_old_probes(old); + tp_func.func = probe; + tp_func.data = data; + ret = tracepoint_remove_func(tp, &tp_func); mutex_unlock(&tracepoints_mutex); - return 0; + return ret; } -EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate); +EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); -/** - * tracepoint_probe_update_all - update tracepoints - */ -void tracepoint_probe_update_all(void) +static void for_each_tracepoint_range( + tracepoint_ptr_t *begin, tracepoint_ptr_t *end, + void (*fct)(struct tracepoint *tp, void *priv), + void *priv) { - LIST_HEAD(release_probes); - struct tp_probes *pos, *next; + tracepoint_ptr_t *iter; - mutex_lock(&tracepoints_mutex); - if (!need_update) { - mutex_unlock(&tracepoints_mutex); + if (!begin) return; - } - if (!list_empty(&old_probes)) - list_replace_init(&old_probes, &release_probes); - need_update = 0; - 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); - } + for (iter = begin; iter < end; iter++) + fct(tracepoint_ptr_deref(iter), priv); } -EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); + +#ifdef CONFIG_MODULES +bool trace_module_has_bad_taint(struct module *mod) +{ + return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) | + (1 << TAINT_UNSIGNED_MODULE) | (1 << TAINT_TEST) | + (1 << TAINT_LIVEPATCH)); +} + +static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list); /** - * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. - * @tracepoint: current tracepoints (in), next tracepoint (out) - * @begin: beginning of the range - * @end: end of the range + * register_tracepoint_module_notifier - register tracepoint coming/going notifier + * @nb: notifier block * - * Returns whether a next tracepoint has been found (1) or not (0). - * Will return the first tracepoint in the range if the input tracepoint is - * NULL. + * Notifiers registered with this function are called on module + * coming/going with the tracepoint_module_list_mutex held. + * The notifier block callback should expect a "struct tp_module" data + * pointer. */ -static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, - struct tracepoint * const *begin, struct tracepoint * const *end) +int register_tracepoint_module_notifier(struct notifier_block *nb) { - if (!*tracepoint && begin != end) { - *tracepoint = begin; - return 1; - } - if (*tracepoint >= begin && *tracepoint < end) - return 1; - return 0; -} + struct tp_module *tp_mod; + int ret; -#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) { - found = tracepoint_get_iter_range(&iter->tracepoint, - __start___tracepoints_ptrs, - __stop___tracepoints_ptrs); - if (found) - goto end; - } - /* 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); + mutex_lock(&tracepoint_module_list_mutex); + ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb); + if (ret) + goto end; + list_for_each_entry(tp_mod, &tracepoint_module_list, list) + (void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod); 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); + mutex_unlock(&tracepoint_module_list_mutex); + return ret; } -#endif /* CONFIG_MODULES */ +EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier); -void tracepoint_iter_start(struct tracepoint_iter *iter) +/** + * unregister_tracepoint_module_notifier - unregister tracepoint coming/going notifier + * @nb: notifier block + * + * The notifier block callback should expect a "struct tp_module" data + * pointer. + */ +int unregister_tracepoint_module_notifier(struct notifier_block *nb) { - tracepoint_get_iter(iter); -} -EXPORT_SYMBOL_GPL(tracepoint_iter_start); + struct tp_module *tp_mod; + int ret; -void tracepoint_iter_next(struct tracepoint_iter *iter) -{ - iter->tracepoint++; - /* - * iter->tracepoint may be invalid because we blindly incremented it. - * Make sure it is valid by marshalling on the tracepoints, getting the - * tracepoints from following modules if necessary. - */ - tracepoint_get_iter(iter); -} -EXPORT_SYMBOL_GPL(tracepoint_iter_next); + mutex_lock(&tracepoint_module_list_mutex); + ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb); + if (ret) + goto end; + list_for_each_entry(tp_mod, &tracepoint_module_list, list) + (void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod); +end: + mutex_unlock(&tracepoint_module_list_mutex); + return ret; -void tracepoint_iter_stop(struct tracepoint_iter *iter) -{ } -EXPORT_SYMBOL_GPL(tracepoint_iter_stop); +EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier); -void tracepoint_iter_reset(struct tracepoint_iter *iter) +/* + * Ensure the tracer unregistered the module's probes before the module + * teardown is performed. Prevents leaks of probe and data pointers. + */ +static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv) { -#ifdef CONFIG_MODULES - iter->module = NULL; -#endif /* CONFIG_MODULES */ - iter->tracepoint = NULL; + WARN_ON_ONCE(tp->funcs); } -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; + struct tp_module *tp_mod; + + if (!mod->num_tracepoints) + return 0; /* * We skip modules that taint the kernel, especially those with different * module headers (for forced load), to make sure we don't cause a crash. - * Staging and out-of-tree GPL modules are fine. + * Staging, out-of-tree, unsigned GPL, and test modules are fine. */ - if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP))) + if (trace_module_has_bad_taint(mod)) 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; + tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); + if (!tp_mod) + return -ENOMEM; + tp_mod->mod = mod; + + mutex_lock(&tracepoint_module_list_mutex); + list_add_tail(&tp_mod->list, &tracepoint_module_list); + blocking_notifier_call_chain(&tracepoint_notify_list, + MODULE_STATE_COMING, tp_mod); + mutex_unlock(&tracepoint_module_list_mutex); + return 0; } -static int tracepoint_module_going(struct module *mod) +static void tracepoint_module_going(struct module *mod) { - struct tp_module *pos; + struct tp_module *tp_mod; - 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); + if (!mod->num_tracepoints) + return; + + mutex_lock(&tracepoint_module_list_mutex); + list_for_each_entry(tp_mod, &tracepoint_module_list, list) { + if (tp_mod->mod == mod) { + blocking_notifier_call_chain(&tracepoint_notify_list, + MODULE_STATE_GOING, tp_mod); + list_del(&tp_mod->list); + kfree(tp_mod); + /* + * Called the going notifier before checking for + * quiescence. + */ + for_each_tracepoint_range(mod->tracepoints_ptrs, + mod->tracepoints_ptrs + mod->num_tracepoints, + tp_module_going_check_quiescent, NULL); break; } } @@ -695,12 +648,11 @@ static int tracepoint_module_going(struct module *mod) * flag on "going", in case a module taints the kernel only after being * loaded. */ - mutex_unlock(&tracepoints_mutex); - return 0; + mutex_unlock(&tracepoint_module_list_mutex); } -int tracepoint_module_notify(struct notifier_block *self, - unsigned long val, void *data) +static int tracepoint_module_notify(struct notifier_block *self, + unsigned long val, void *data) { struct module *mod = data; int ret = 0; @@ -712,58 +664,119 @@ int tracepoint_module_notify(struct notifier_block *self, case MODULE_STATE_LIVE: break; case MODULE_STATE_GOING: - ret = tracepoint_module_going(mod); + tracepoint_module_going(mod); + break; + case MODULE_STATE_UNFORMED: break; } - return ret; + return notifier_from_errno(ret); } -struct notifier_block tracepoint_module_nb = { +static struct notifier_block tracepoint_module_nb = { .notifier_call = tracepoint_module_notify, .priority = 0, }; -static int init_tracepoints(void) +static __init int init_tracepoints(void) { - return register_module_notifier(&tracepoint_module_nb); + int ret; + + ret = register_module_notifier(&tracepoint_module_nb); + if (ret) + pr_warn("Failed to register tracepoint module enter notifier\n"); + + return ret; } __initcall(init_tracepoints); + +/** + * for_each_tracepoint_in_module - iteration on all tracepoints in a module + * @mod: module + * @fct: callback + * @priv: private data + */ +void for_each_tracepoint_in_module(struct module *mod, + void (*fct)(struct tracepoint *tp, + struct module *mod, void *priv), + void *priv) +{ + tracepoint_ptr_t *begin, *end, *iter; + + lockdep_assert_held(&tracepoint_module_list_mutex); + + if (!mod) + return; + + begin = mod->tracepoints_ptrs; + end = mod->tracepoints_ptrs + mod->num_tracepoints; + + for (iter = begin; iter < end; iter++) + fct(tracepoint_ptr_deref(iter), mod, priv); +} + +/** + * for_each_module_tracepoint - iteration on all tracepoints in all modules + * @fct: callback + * @priv: private data + */ +void for_each_module_tracepoint(void (*fct)(struct tracepoint *tp, + struct module *mod, void *priv), + void *priv) +{ + struct tp_module *tp_mod; + + mutex_lock(&tracepoint_module_list_mutex); + list_for_each_entry(tp_mod, &tracepoint_module_list, list) + for_each_tracepoint_in_module(tp_mod->mod, fct, priv); + mutex_unlock(&tracepoint_module_list_mutex); +} #endif /* CONFIG_MODULES */ +/** + * for_each_kernel_tracepoint - iteration on all kernel tracepoints + * @fct: callback + * @priv: private data + */ +void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv), + void *priv) +{ + for_each_tracepoint_range(__start___tracepoints_ptrs, + __stop___tracepoints_ptrs, fct, priv); +} +EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint); + #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ static int sys_tracepoint_refcount; -void syscall_regfunc(void) +int syscall_regfunc(void) { - unsigned long flags; - struct task_struct *g, *t; + struct task_struct *p, *t; if (!sys_tracepoint_refcount) { - read_lock_irqsave(&tasklist_lock, flags); - do_each_thread(g, t) { - /* Skip kernel threads. */ - if (t->mm) - set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); - } while_each_thread(g, t); - read_unlock_irqrestore(&tasklist_lock, flags); + read_lock(&tasklist_lock); + for_each_process_thread(p, t) { + set_task_syscall_work(t, SYSCALL_TRACEPOINT); + } + read_unlock(&tasklist_lock); } sys_tracepoint_refcount++; + + return 0; } void syscall_unregfunc(void) { - unsigned long flags; - struct task_struct *g, *t; + struct task_struct *p, *t; sys_tracepoint_refcount--; if (!sys_tracepoint_refcount) { - read_lock_irqsave(&tasklist_lock, flags); - do_each_thread(g, t) { - clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); - } while_each_thread(g, t); - read_unlock_irqrestore(&tasklist_lock, flags); + read_lock(&tasklist_lock); + for_each_process_thread(p, t) { + clear_task_syscall_work(t, SYSCALL_TRACEPOINT); + } + read_unlock(&tasklist_lock); } } #endif |