// 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, 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, 1, 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, 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, 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, 1, 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, 1, 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, 1, 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, 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;
}
