1 files changed, 447 insertions, 0 deletions

diff --git a/tools/lib/lockdep/preload.c b/tools/lib/lockdep/preload.c
new file mode 100644
index 000000000000..23bd69cb5ade
--- /dev/null
+++ b/tools/lib/lockdep/preload.c
@@ -0,0 +1,447 @@
+#define _GNU_SOURCE
+#include <pthread.h>
+#include <stdio.h>
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <sysexits.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
+
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
+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)) {
+                        fprintf(stderr,
+                "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, 2, 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, 0, (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, 2, NULL, (unsigned long)_RET_IP_);
+        r = ll_pthread_mutex_trylock(mutex);
+        if (r)
+                lock_release(&__get_lock(mutex)->dep_map, 0, (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, 0, (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, 2, 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, 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, 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, 2, NULL, (unsigned long)_RET_IP_);
+        r = ll_pthread_rwlock_rdlock(rwlock);
+        if (r)
+                lock_release(&__get_lock(rwlock)->dep_map, 0, (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, 2, NULL, (unsigned long)_RET_IP_);
+        r = ll_pthread_rwlock_tryrdlock(rwlock);
+        if (r)
+                lock_release(&__get_lock(rwlock)->dep_map, 0, (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, 2, NULL, (unsigned long)_RET_IP_);
+        r = ll_pthread_rwlock_trywrlock(rwlock);
+        if (r)
+                lock_release(&__get_lock(rwlock)->dep_map, 0, (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, 2, NULL, (unsigned long)_RET_IP_);
+        r = ll_pthread_rwlock_wrlock(rwlock);
+        if (r)
+                lock_release(&__get_lock(rwlock)->dep_map, 0, (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, 0, (unsigned long)_RET_IP_);
+        r = ll_pthread_rwlock_unlock(rwlock);
+        if (r)
+                lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 0, 2, 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
+
+        printf("%p\n", ll_pthread_mutex_trylock);fflush(stdout);
+
+        lockdep_init();
+
+        __init_state = done;
+}