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Diffstat (limited to '')
| -rw-r--r-- | tools/lib/lockdep/preload.c | 443 |
1 files changed, 443 insertions, 0 deletions
diff --git a/tools/lib/lockdep/preload.c b/tools/lib/lockdep/preload.c new file mode 100644 index 000000000..8f1adbe88 --- /dev/null +++ b/tools/lib/lockdep/preload.c @@ -0,0 +1,443 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <pthread.h> +#include <stdio.h> +#include <dlfcn.h> +#include <stdlib.h> +#include <sysexits.h> +#include <unistd.h> +#include "include/liblockdep/mutex.h" +#include "../../include/linux/rbtree.h" + +/** + * struct lock_lookup - liblockdep's view of a single unique lock + * @orig: pointer to the original pthread lock, used for lookups + * @dep_map: lockdep's dep_map structure + * @key: lockdep's key structure + * @node: rb-tree node used to store the lock in a global tree + * @name: a unique name for the lock + */ +struct lock_lookup { + void *orig; /* Original pthread lock, used for lookups */ + struct lockdep_map dep_map; /* Since all locks are dynamic, we need + * a dep_map and a key for each lock */ + /* + * Wait, there's no support for key classes? Yup :( + * Most big projects wrap the pthread api with their own calls to + * be compatible with different locking methods. This means that + * "classes" will be brokes since the function that creates all + * locks will point to a generic locking function instead of the + * actual code that wants to do the locking. + */ + struct lock_class_key key; + struct rb_node node; +#define LIBLOCKDEP_MAX_LOCK_NAME 22 + char name[LIBLOCKDEP_MAX_LOCK_NAME]; +}; + +/* This is where we store our locks */ +static struct rb_root locks = RB_ROOT; +static pthread_rwlock_t locks_rwlock = PTHREAD_RWLOCK_INITIALIZER; + +/* pthread mutex API */ + +#ifdef __GLIBC__ +extern int __pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr); +extern int __pthread_mutex_lock(pthread_mutex_t *mutex); +extern int __pthread_mutex_trylock(pthread_mutex_t *mutex); +extern int __pthread_mutex_unlock(pthread_mutex_t *mutex); +extern int __pthread_mutex_destroy(pthread_mutex_t *mutex); +#else +#define __pthread_mutex_init NULL +#define __pthread_mutex_lock NULL +#define __pthread_mutex_trylock NULL +#define __pthread_mutex_unlock NULL +#define __pthread_mutex_destroy NULL +#endif +static int (*ll_pthread_mutex_init)(pthread_mutex_t *mutex, + const pthread_mutexattr_t *attr) = __pthread_mutex_init; +static int (*ll_pthread_mutex_lock)(pthread_mutex_t *mutex) = __pthread_mutex_lock; +static int (*ll_pthread_mutex_trylock)(pthread_mutex_t *mutex) = __pthread_mutex_trylock; +static int (*ll_pthread_mutex_unlock)(pthread_mutex_t *mutex) = __pthread_mutex_unlock; +static int (*ll_pthread_mutex_destroy)(pthread_mutex_t *mutex) = __pthread_mutex_destroy; + +/* pthread rwlock API */ + +#ifdef __GLIBC__ +extern int __pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr); +extern int __pthread_rwlock_destroy(pthread_rwlock_t *rwlock); +extern int __pthread_rwlock_wrlock(pthread_rwlock_t *rwlock); +extern int __pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock); +extern int __pthread_rwlock_rdlock(pthread_rwlock_t *rwlock); +extern int __pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock); +extern int __pthread_rwlock_unlock(pthread_rwlock_t *rwlock); +#else +#define __pthread_rwlock_init NULL +#define __pthread_rwlock_destroy NULL +#define __pthread_rwlock_wrlock NULL +#define __pthread_rwlock_trywrlock NULL +#define __pthread_rwlock_rdlock NULL +#define __pthread_rwlock_tryrdlock NULL +#define __pthread_rwlock_unlock NULL +#endif + +static int (*ll_pthread_rwlock_init)(pthread_rwlock_t *rwlock, + const pthread_rwlockattr_t *attr) = __pthread_rwlock_init; +static int (*ll_pthread_rwlock_destroy)(pthread_rwlock_t *rwlock) = __pthread_rwlock_destroy; +static int (*ll_pthread_rwlock_rdlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_rdlock; +static int (*ll_pthread_rwlock_tryrdlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_tryrdlock; +static int (*ll_pthread_rwlock_trywrlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_trywrlock; +static int (*ll_pthread_rwlock_wrlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_wrlock; +static int (*ll_pthread_rwlock_unlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_unlock; + +enum { none, prepare, done, } __init_state; +static void init_preload(void); +static void try_init_preload(void) +{ + if (__init_state != done) + init_preload(); +} + +static struct rb_node **__get_lock_node(void *lock, struct rb_node **parent) +{ + struct rb_node **node = &locks.rb_node; + struct lock_lookup *l; + + *parent = NULL; + + while (*node) { + l = rb_entry(*node, struct lock_lookup, node); + + *parent = *node; + if (lock < l->orig) + node = &l->node.rb_left; + else if (lock > l->orig) + node = &l->node.rb_right; + else + return node; + } + + return node; +} + +#ifndef LIBLOCKDEP_STATIC_ENTRIES +#define LIBLOCKDEP_STATIC_ENTRIES 1024 +#endif + +static struct lock_lookup __locks[LIBLOCKDEP_STATIC_ENTRIES]; +static int __locks_nr; + +static inline bool is_static_lock(struct lock_lookup *lock) +{ + return lock >= __locks && lock < __locks + ARRAY_SIZE(__locks); +} + +static struct lock_lookup *alloc_lock(void) +{ + if (__init_state != done) { + /* + * Some programs attempt to initialize and use locks in their + * allocation path. This means that a call to malloc() would + * result in locks being initialized and locked. + * + * Why is it an issue for us? dlsym() below will try allocating + * to give us the original function. Since this allocation will + * result in a locking operations, we have to let pthread deal + * with it, but we can't! we don't have the pointer to the + * original API since we're inside dlsym() trying to get it + */ + + int idx = __locks_nr++; + if (idx >= ARRAY_SIZE(__locks)) { + dprintf(STDERR_FILENO, + "LOCKDEP error: insufficient LIBLOCKDEP_STATIC_ENTRIES\n"); + exit(EX_UNAVAILABLE); + } + return __locks + idx; + } + + return malloc(sizeof(struct lock_lookup)); +} + +static inline void free_lock(struct lock_lookup *lock) +{ + if (likely(!is_static_lock(lock))) + free(lock); +} + +/** + * __get_lock - find or create a lock instance + * @lock: pointer to a pthread lock function + * + * Try to find an existing lock in the rbtree using the provided pointer. If + * one wasn't found - create it. + */ +static struct lock_lookup *__get_lock(void *lock) +{ + struct rb_node **node, *parent; + struct lock_lookup *l; + + ll_pthread_rwlock_rdlock(&locks_rwlock); + node = __get_lock_node(lock, &parent); + ll_pthread_rwlock_unlock(&locks_rwlock); + if (*node) { + return rb_entry(*node, struct lock_lookup, node); + } + + /* We didn't find the lock, let's create it */ + l = alloc_lock(); + if (l == NULL) + return NULL; + + l->orig = lock; + /* + * Currently the name of the lock is the ptr value of the pthread lock, + * while not optimal, it makes debugging a bit easier. + * + * TODO: Get the real name of the lock using libdwarf + */ + sprintf(l->name, "%p", lock); + lockdep_init_map(&l->dep_map, l->name, &l->key, 0); + + ll_pthread_rwlock_wrlock(&locks_rwlock); + /* This might have changed since the last time we fetched it */ + node = __get_lock_node(lock, &parent); + rb_link_node(&l->node, parent, node); + rb_insert_color(&l->node, &locks); + ll_pthread_rwlock_unlock(&locks_rwlock); + + return l; +} + +static void __del_lock(struct lock_lookup *lock) +{ + ll_pthread_rwlock_wrlock(&locks_rwlock); + rb_erase(&lock->node, &locks); + ll_pthread_rwlock_unlock(&locks_rwlock); + free_lock(lock); +} + +int pthread_mutex_init(pthread_mutex_t *mutex, + const pthread_mutexattr_t *attr) +{ + int r; + + /* + * We keep trying to init our preload module because there might be + * code in init sections that tries to touch locks before we are + * initialized, in that case we'll need to manually call preload + * to get us going. + * + * Funny enough, kernel's lockdep had the same issue, and used + * (almost) the same solution. See look_up_lock_class() in + * kernel/locking/lockdep.c for details. + */ + try_init_preload(); + + r = ll_pthread_mutex_init(mutex, attr); + if (r == 0) + /* + * We do a dummy initialization here so that lockdep could + * warn us if something fishy is going on - such as + * initializing a held lock. + */ + __get_lock(mutex); + + return r; +} + +int pthread_mutex_lock(pthread_mutex_t *mutex) +{ + int r; + + try_init_preload(); + + lock_acquire(&__get_lock(mutex)->dep_map, 0, 0, 0, 1, NULL, + (unsigned long)_RET_IP_); + /* + * Here's the thing with pthread mutexes: unlike the kernel variant, + * they can fail. + * + * This means that the behaviour here is a bit different from what's + * going on in the kernel: there we just tell lockdep that we took the + * lock before actually taking it, but here we must deal with the case + * that locking failed. + * + * To do that we'll "release" the lock if locking failed - this way + * we'll get lockdep doing the correct checks when we try to take + * the lock, and if that fails - we'll be back to the correct + * state by releasing it. + */ + r = ll_pthread_mutex_lock(mutex); + if (r) + lock_release(&__get_lock(mutex)->dep_map, (unsigned long)_RET_IP_); + + return r; +} + +int pthread_mutex_trylock(pthread_mutex_t *mutex) +{ + int r; + + try_init_preload(); + + lock_acquire(&__get_lock(mutex)->dep_map, 0, 1, 0, 1, NULL, (unsigned long)_RET_IP_); + r = ll_pthread_mutex_trylock(mutex); + if (r) + lock_release(&__get_lock(mutex)->dep_map, (unsigned long)_RET_IP_); + + return r; +} + +int pthread_mutex_unlock(pthread_mutex_t *mutex) +{ + int r; + + try_init_preload(); + + lock_release(&__get_lock(mutex)->dep_map, (unsigned long)_RET_IP_); + /* + * Just like taking a lock, only in reverse! + * + * If we fail releasing the lock, tell lockdep we're holding it again. + */ + r = ll_pthread_mutex_unlock(mutex); + if (r) + lock_acquire(&__get_lock(mutex)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_); + + return r; +} + +int pthread_mutex_destroy(pthread_mutex_t *mutex) +{ + try_init_preload(); + + /* + * Let's see if we're releasing a lock that's held. + * + * TODO: Hook into free() and add that check there as well. + */ + debug_check_no_locks_freed(mutex, sizeof(*mutex)); + __del_lock(__get_lock(mutex)); + return ll_pthread_mutex_destroy(mutex); +} + +/* This is the rwlock part, very similar to what happened with mutex above */ +int pthread_rwlock_init(pthread_rwlock_t *rwlock, + const pthread_rwlockattr_t *attr) +{ + int r; + + try_init_preload(); + + r = ll_pthread_rwlock_init(rwlock, attr); + if (r == 0) + __get_lock(rwlock); + + return r; +} + +int pthread_rwlock_destroy(pthread_rwlock_t *rwlock) +{ + try_init_preload(); + + debug_check_no_locks_freed(rwlock, sizeof(*rwlock)); + __del_lock(__get_lock(rwlock)); + return ll_pthread_rwlock_destroy(rwlock); +} + +int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock) +{ + int r; + + init_preload(); + + lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 2, 1, NULL, (unsigned long)_RET_IP_); + r = ll_pthread_rwlock_rdlock(rwlock); + if (r) + lock_release(&__get_lock(rwlock)->dep_map, (unsigned long)_RET_IP_); + + return r; +} + +int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock) +{ + int r; + + init_preload(); + + lock_acquire(&__get_lock(rwlock)->dep_map, 0, 1, 2, 1, NULL, (unsigned long)_RET_IP_); + r = ll_pthread_rwlock_tryrdlock(rwlock); + if (r) + lock_release(&__get_lock(rwlock)->dep_map, (unsigned long)_RET_IP_); + + return r; +} + +int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock) +{ + int r; + + init_preload(); + + lock_acquire(&__get_lock(rwlock)->dep_map, 0, 1, 0, 1, NULL, (unsigned long)_RET_IP_); + r = ll_pthread_rwlock_trywrlock(rwlock); + if (r) + lock_release(&__get_lock(rwlock)->dep_map, (unsigned long)_RET_IP_); + + return r; +} + +int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock) +{ + int r; + + init_preload(); + + lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_); + r = ll_pthread_rwlock_wrlock(rwlock); + if (r) + lock_release(&__get_lock(rwlock)->dep_map, (unsigned long)_RET_IP_); + + return r; +} + +int pthread_rwlock_unlock(pthread_rwlock_t *rwlock) +{ + int r; + + init_preload(); + + lock_release(&__get_lock(rwlock)->dep_map, (unsigned long)_RET_IP_); + r = ll_pthread_rwlock_unlock(rwlock); + if (r) + lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_); + + return r; +} + +__attribute__((constructor)) static void init_preload(void) +{ + if (__init_state == done) + return; + +#ifndef __GLIBC__ + __init_state = prepare; + + ll_pthread_mutex_init = dlsym(RTLD_NEXT, "pthread_mutex_init"); + ll_pthread_mutex_lock = dlsym(RTLD_NEXT, "pthread_mutex_lock"); + ll_pthread_mutex_trylock = dlsym(RTLD_NEXT, "pthread_mutex_trylock"); + ll_pthread_mutex_unlock = dlsym(RTLD_NEXT, "pthread_mutex_unlock"); + ll_pthread_mutex_destroy = dlsym(RTLD_NEXT, "pthread_mutex_destroy"); + + ll_pthread_rwlock_init = dlsym(RTLD_NEXT, "pthread_rwlock_init"); + ll_pthread_rwlock_destroy = dlsym(RTLD_NEXT, "pthread_rwlock_destroy"); + ll_pthread_rwlock_rdlock = dlsym(RTLD_NEXT, "pthread_rwlock_rdlock"); + ll_pthread_rwlock_tryrdlock = dlsym(RTLD_NEXT, "pthread_rwlock_tryrdlock"); + ll_pthread_rwlock_wrlock = dlsym(RTLD_NEXT, "pthread_rwlock_wrlock"); + ll_pthread_rwlock_trywrlock = dlsym(RTLD_NEXT, "pthread_rwlock_trywrlock"); + ll_pthread_rwlock_unlock = dlsym(RTLD_NEXT, "pthread_rwlock_unlock"); +#endif + + __init_state = done; +} |