/*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2009-2021 Dmitry Chagin * Copyright (c) 2008 Roman Divacky * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include #include #include #include #include #include #include #include #include #ifdef COMPAT_LINUX32 #include #include #else #include #include #endif #include #include #include #include #include #define FUTEX_SHARED 0x8 /* shared futex */ #define FUTEX_UNOWNED 0 #define GET_SHARED(a) (a->flags & FUTEX_SHARED) ? AUTO_SHARE : THREAD_SHARE static int futex_atomic_op(struct thread *, int, uint32_t *, int *); static int handle_futex_death(struct thread *td, struct linux_emuldata *, uint32_t *, unsigned int, bool); static int fetch_robust_entry(struct linux_robust_list **, struct linux_robust_list **, unsigned int *); struct linux_futex_args { uint32_t *uaddr; int32_t op; uint32_t flags; bool clockrt; uint32_t val; struct timespec *ts; uint32_t *uaddr2; uint32_t val3; bool val3_compare; struct timespec kts; }; static inline int futex_key_get(const void *, int, int, struct umtx_key *); static void linux_umtx_abs_timeout_init(struct umtx_abs_timeout *, struct linux_futex_args *); static int linux_futex(struct thread *, struct linux_futex_args *); static int linux_futex_wait(struct thread *, struct linux_futex_args *); static int linux_futex_wake(struct thread *, struct linux_futex_args *); static int linux_futex_requeue(struct thread *, struct linux_futex_args *); static int linux_futex_wakeop(struct thread *, struct linux_futex_args *); static int linux_futex_lock_pi(struct thread *, bool, struct linux_futex_args *); static int linux_futex_unlock_pi(struct thread *, bool, struct linux_futex_args *); static int futex_wake_pi(struct thread *, uint32_t *, bool); static int futex_key_get(const void *uaddr, int type, int share, struct umtx_key *key) { /* Check that futex address is a 32bit aligned. */ if (!__is_aligned(uaddr, sizeof(uint32_t))) return (EINVAL); return (umtx_key_get(uaddr, type, share, key)); } int futex_wake(struct thread *td, uint32_t *uaddr, int val, bool shared) { struct linux_futex_args args; bzero(&args, sizeof(args)); args.op = LINUX_FUTEX_WAKE; args.uaddr = uaddr; args.flags = shared == true ? FUTEX_SHARED : 0; args.val = val; args.val3 = FUTEX_BITSET_MATCH_ANY; return (linux_futex_wake(td, &args)); } static int futex_wake_pi(struct thread *td, uint32_t *uaddr, bool shared) { struct linux_futex_args args; bzero(&args, sizeof(args)); args.op = LINUX_FUTEX_UNLOCK_PI; args.uaddr = uaddr; args.flags = shared == true ? FUTEX_SHARED : 0; return (linux_futex_unlock_pi(td, true, &args)); } static int futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr, int *res) { int op = (encoded_op >> 28) & 7; int cmp = (encoded_op >> 24) & 15; int oparg = (encoded_op << 8) >> 20; int cmparg = (encoded_op << 20) >> 20; int oldval = 0, ret; if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) oparg = 1 << oparg; switch (op) { case FUTEX_OP_SET: ret = futex_xchgl(oparg, uaddr, &oldval); break; case FUTEX_OP_ADD: ret = futex_addl(oparg, uaddr, &oldval); break; case FUTEX_OP_OR: ret = futex_orl(oparg, uaddr, &oldval); break; case FUTEX_OP_ANDN: ret = futex_andl(~oparg, uaddr, &oldval); break; case FUTEX_OP_XOR: ret = futex_xorl(oparg, uaddr, &oldval); break; default: ret = ENOSYS; break; } if (ret != 0) return (ret); switch (cmp) { case FUTEX_OP_CMP_EQ: *res = (oldval == cmparg); break; case FUTEX_OP_CMP_NE: *res = (oldval != cmparg); break; case FUTEX_OP_CMP_LT: *res = (oldval < cmparg); break; case FUTEX_OP_CMP_GE: *res = (oldval >= cmparg); break; case FUTEX_OP_CMP_LE: *res = (oldval <= cmparg); break; case FUTEX_OP_CMP_GT: *res = (oldval > cmparg); break; default: ret = ENOSYS; } return (ret); } static int linux_futex(struct thread *td, struct linux_futex_args *args) { struct linux_pemuldata *pem; struct proc *p; if (args->op & LINUX_FUTEX_PRIVATE_FLAG) { args->flags = 0; args->op &= ~LINUX_FUTEX_PRIVATE_FLAG; } else args->flags = FUTEX_SHARED; args->clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME; args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME; if (args->clockrt && args->op != LINUX_FUTEX_WAIT_BITSET && args->op != LINUX_FUTEX_WAIT_REQUEUE_PI && args->op != LINUX_FUTEX_LOCK_PI2) return (ENOSYS); switch (args->op) { case LINUX_FUTEX_WAIT: args->val3 = FUTEX_BITSET_MATCH_ANY; /* FALLTHROUGH */ case LINUX_FUTEX_WAIT_BITSET: LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x", args->uaddr, args->val, args->val3); return (linux_futex_wait(td, args)); case LINUX_FUTEX_WAKE: args->val3 = FUTEX_BITSET_MATCH_ANY; /* FALLTHROUGH */ case LINUX_FUTEX_WAKE_BITSET: LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x", args->uaddr, args->val, args->val3); return (linux_futex_wake(td, args)); case LINUX_FUTEX_REQUEUE: /* * Glibc does not use this operation since version 2.3.3, * as it is racy and replaced by FUTEX_CMP_REQUEUE operation. * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when * FUTEX_REQUEUE returned EINVAL. */ pem = pem_find(td->td_proc); if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) { linux_msg(td, "unsupported FUTEX_REQUEUE"); pem->flags |= LINUX_XDEPR_REQUEUEOP; } /* * The above is true, however musl libc does make use of the * futex requeue operation, allow operation for brands which * set LINUX_BI_FUTEX_REQUEUE bit of Brandinfo flags. */ p = td->td_proc; Elf_Brandinfo *bi = p->p_elf_brandinfo; if (bi == NULL || ((bi->flags & LINUX_BI_FUTEX_REQUEUE)) == 0) return (EINVAL); args->val3_compare = false; /* FALLTHROUGH */ case LINUX_FUTEX_CMP_REQUEUE: LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p " "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x", args->uaddr, args->val, args->val3, args->uaddr2, args->ts); return (linux_futex_requeue(td, args)); case LINUX_FUTEX_WAKE_OP: LINUX_CTR5(sys_futex, "WAKE_OP " "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x", args->uaddr, args->val, args->uaddr2, args->val3, args->ts); return (linux_futex_wakeop(td, args)); case LINUX_FUTEX_LOCK_PI: args->clockrt = true; /* FALLTHROUGH */ case LINUX_FUTEX_LOCK_PI2: LINUX_CTR2(sys_futex, "LOCKPI uaddr %p val 0x%x", args->uaddr, args->val); return (linux_futex_lock_pi(td, false, args)); case LINUX_FUTEX_UNLOCK_PI: LINUX_CTR1(sys_futex, "UNLOCKPI uaddr %p", args->uaddr); return (linux_futex_unlock_pi(td, false, args)); case LINUX_FUTEX_TRYLOCK_PI: LINUX_CTR1(sys_futex, "TRYLOCKPI uaddr %p", args->uaddr); return (linux_futex_lock_pi(td, true, args)); /* * Current implementation of FUTEX_WAIT_REQUEUE_PI and FUTEX_CMP_REQUEUE_PI * can't be used anymore to implement conditional variables. * A detailed explanation can be found here: * * https://sourceware.org/bugzilla/show_bug.cgi?id=13165 * and here http://austingroupbugs.net/view.php?id=609 * * And since commit * https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ed19993b5b0d05d62cc883571519a67dae481a14 * glibc does not use them. */ case LINUX_FUTEX_WAIT_REQUEUE_PI: /* not yet implemented */ pem = pem_find(td->td_proc); if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) { linux_msg(td, "unsupported FUTEX_WAIT_REQUEUE_PI"); pem->flags |= LINUX_XUNSUP_FUTEXPIOP; } return (ENOSYS); case LINUX_FUTEX_CMP_REQUEUE_PI: /* not yet implemented */ pem = pem_find(td->td_proc); if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) { linux_msg(td, "unsupported FUTEX_CMP_REQUEUE_PI"); pem->flags |= LINUX_XUNSUP_FUTEXPIOP; } return (ENOSYS); default: linux_msg(td, "unsupported futex op %d", args->op); return (ENOSYS); } } /* * pi protocol: * - 0 futex word value means unlocked. * - TID futex word value means locked. * Userspace uses atomic ops to lock/unlock these futexes without entering the * kernel. If the lock-acquire fastpath fails, (transition from 0 to TID fails), * then FUTEX_LOCK_PI is called. * The kernel atomically set FUTEX_WAITERS bit in the futex word value, if no * other waiters exists looks up the thread that owns the futex (it has put its * own TID into the futex value) and made this thread the owner of the internal * pi-aware lock object (mutex). Then the kernel tries to lock the internal lock * object, on which it blocks. Once it returns, it has the mutex acquired, and it * sets the futex value to its own TID and returns (futex value contains * FUTEX_WAITERS|TID). * The unlock fastpath would fail (because the FUTEX_WAITERS bit is set) and * FUTEX_UNLOCK_PI will be called. * If a futex is found to be held at exit time, the kernel sets the OWNER_DIED * bit of the futex word and wakes up the next futex waiter (if any), WAITERS * bit is preserved (if any). * If OWNER_DIED bit is set the kernel sanity checks the futex word value against * the internal futex state and if correct, acquire futex. */ static int linux_futex_lock_pi(struct thread *td, bool try, struct linux_futex_args *args) { struct umtx_abs_timeout timo; struct linux_emuldata *em; struct umtx_pi *pi, *new_pi; struct thread *td1; struct umtx_q *uq; int error, rv; uint32_t owner, old_owner; em = em_find(td); uq = td->td_umtxq; error = futex_key_get(args->uaddr, TYPE_PI_FUTEX, GET_SHARED(args), &uq->uq_key); if (error != 0) return (error); if (args->ts != NULL) linux_umtx_abs_timeout_init(&timo, args); umtxq_lock(&uq->uq_key); pi = umtx_pi_lookup(&uq->uq_key); if (pi == NULL) { new_pi = umtx_pi_alloc(M_NOWAIT); if (new_pi == NULL) { umtxq_unlock(&uq->uq_key); new_pi = umtx_pi_alloc(M_WAITOK); umtxq_lock(&uq->uq_key); pi = umtx_pi_lookup(&uq->uq_key); if (pi != NULL) { umtx_pi_free(new_pi); new_pi = NULL; } } if (new_pi != NULL) { new_pi->pi_key = uq->uq_key; umtx_pi_insert(new_pi); pi = new_pi; } } umtx_pi_ref(pi); umtxq_unlock(&uq->uq_key); for (;;) { /* Try uncontested case first. */ rv = casueword32(args->uaddr, FUTEX_UNOWNED, &owner, em->em_tid); /* The acquire succeeded. */ if (rv == 0) { error = 0; break; } if (rv == -1) { error = EFAULT; break; } /* * Nobody owns it, but the acquire failed. This can happen * with ll/sc atomic. */ if (owner == FUTEX_UNOWNED) { error = thread_check_susp(td, true); if (error != 0) break; continue; } /* * Avoid overwriting a possible error from sleep due * to the pending signal with suspension check result. */ if (error == 0) { error = thread_check_susp(td, true); if (error != 0) break; } /* The futex word at *uaddr is already locked by the caller. */ if ((owner & FUTEX_TID_MASK) == em->em_tid) { error = EDEADLK; break; } /* * Futex owner died, handle_futex_death() set the OWNER_DIED bit * and clear tid. Try to acquire it. */ if ((owner & FUTEX_TID_MASK) == FUTEX_UNOWNED) { old_owner = owner; owner = owner & (FUTEX_WAITERS | FUTEX_OWNER_DIED); owner |= em->em_tid; rv = casueword32(args->uaddr, old_owner, &owner, owner); if (rv == -1) { error = EFAULT; break; } if (rv == 1) { if (error == 0) { error = thread_check_susp(td, true); if (error != 0) break; } /* * If this failed the lock could * changed, restart. */ continue; } umtxq_lock(&uq->uq_key); umtxq_busy(&uq->uq_key); error = umtx_pi_claim(pi, td); umtxq_unbusy(&uq->uq_key); umtxq_unlock(&uq->uq_key); if (error != 0) { /* * Since we're going to return an * error, restore the futex to its * previous, unowned state to avoid * compounding the problem. */ (void)casuword32(args->uaddr, owner, old_owner); } break; } /* * Inconsistent state: OWNER_DIED is set and tid is not 0. * Linux does some checks of futex state, we return EINVAL, * as the user space can take care of this. */ if ((owner & FUTEX_OWNER_DIED) != FUTEX_UNOWNED) { error = EINVAL; break; } if (try != 0) { error = EBUSY; break; } /* * If we caught a signal, we have retried and now * exit immediately. */ if (error != 0) break; umtxq_lock(&uq->uq_key); umtxq_busy(&uq->uq_key); umtxq_unlock(&uq->uq_key); /* * Set the contested bit so that a release in user space knows * to use the system call for unlock. If this fails either some * one else has acquired the lock or it has been released. */ rv = casueword32(args->uaddr, owner, &owner, owner | FUTEX_WAITERS); if (rv == -1) { umtxq_unbusy_unlocked(&uq->uq_key); error = EFAULT; break; } if (rv == 1) { umtxq_unbusy_unlocked(&uq->uq_key); error = thread_check_susp(td, true); if (error != 0) break; /* * The lock changed and we need to retry or we * lost a race to the thread unlocking the umtx. */ continue; } /* * Substitute Linux thread id by native thread id to * avoid refactoring code of umtxq_sleep_pi(). */ td1 = linux_tdfind(td, owner & FUTEX_TID_MASK, -1); if (td1 != NULL) { owner = td1->td_tid; PROC_UNLOCK(td1->td_proc); } else { umtxq_unbusy_unlocked(&uq->uq_key); error = EINVAL; break; } umtxq_lock(&uq->uq_key); /* We set the contested bit, sleep. */ error = umtxq_sleep_pi(uq, pi, owner, "futexp", args->ts == NULL ? NULL : &timo, (args->flags & FUTEX_SHARED) != 0); if (error != 0) continue; error = thread_check_susp(td, false); if (error != 0) break; } umtxq_lock(&uq->uq_key); umtx_pi_unref(pi); umtxq_unlock(&uq->uq_key); umtx_key_release(&uq->uq_key); return (error); } static int linux_futex_unlock_pi(struct thread *td, bool rb, struct linux_futex_args *args) { struct linux_emuldata *em; struct umtx_key key; uint32_t old, owner, new_owner; int count, error; em = em_find(td); /* * Make sure we own this mtx. */ error = fueword32(args->uaddr, &owner); if (error == -1) return (EFAULT); if (!rb && (owner & FUTEX_TID_MASK) != em->em_tid) return (EPERM); error = futex_key_get(args->uaddr, TYPE_PI_FUTEX, GET_SHARED(args), &key); if (error != 0) return (error); umtxq_lock(&key); umtxq_busy(&key); error = umtx_pi_drop(td, &key, rb, &count); if (error != 0 || rb) { umtxq_unbusy(&key); umtxq_unlock(&key); umtx_key_release(&key); return (error); } umtxq_unlock(&key); /* * When unlocking the futex, it must be marked as unowned if * there is zero or one thread only waiting for it. * Otherwise, it must be marked as contested. */ if (count > 1) new_owner = FUTEX_WAITERS; else new_owner = FUTEX_UNOWNED; again: error = casueword32(args->uaddr, owner, &old, new_owner); if (error == 1) { error = thread_check_susp(td, false); if (error == 0) goto again; } umtxq_unbusy_unlocked(&key); umtx_key_release(&key); if (error == -1) return (EFAULT); if (error == 0 && old != owner) return (EINVAL); return (error); } static int linux_futex_wakeop(struct thread *td, struct linux_futex_args *args) { struct umtx_key key, key2; int nrwake, op_ret, ret; int error, count; if (args->uaddr == args->uaddr2) return (EINVAL); error = futex_key_get(args->uaddr, TYPE_FUTEX, GET_SHARED(args), &key); if (error != 0) return (error); error = futex_key_get(args->uaddr2, TYPE_FUTEX, GET_SHARED(args), &key2); if (error != 0) { umtx_key_release(&key); return (error); } umtxq_lock(&key); umtxq_busy(&key); umtxq_unlock(&key); error = futex_atomic_op(td, args->val3, args->uaddr2, &op_ret); umtxq_lock(&key); umtxq_unbusy(&key); if (error != 0) goto out; ret = umtxq_signal_mask(&key, args->val, args->val3); if (op_ret > 0) { nrwake = (int)(unsigned long)args->ts; umtxq_lock(&key2); count = umtxq_count(&key2); if (count > 0) ret += umtxq_signal_mask(&key2, nrwake, args->val3); else ret += umtxq_signal_mask(&key, nrwake, args->val3); umtxq_unlock(&key2); } td->td_retval[0] = ret; out: umtxq_unlock(&key); umtx_key_release(&key2); umtx_key_release(&key); return (error); } static int linux_futex_requeue(struct thread *td, struct linux_futex_args *args) { int nrwake, nrrequeue; struct umtx_key key, key2; int error; uint32_t uval; /* * Linux allows this, we would not, it is an incorrect * usage of declared ABI, so return EINVAL. */ if (args->uaddr == args->uaddr2) return (EINVAL); nrrequeue = (int)(unsigned long)args->ts; nrwake = args->val; /* * Sanity check to prevent signed integer overflow, * see Linux CVE-2018-6927 */ if (nrwake < 0 || nrrequeue < 0) return (EINVAL); error = futex_key_get(args->uaddr, TYPE_FUTEX, GET_SHARED(args), &key); if (error != 0) return (error); error = futex_key_get(args->uaddr2, TYPE_FUTEX, GET_SHARED(args), &key2); if (error != 0) { umtx_key_release(&key); return (error); } umtxq_lock(&key); umtxq_busy(&key); umtxq_unlock(&key); error = fueword32(args->uaddr, &uval); if (error != 0) error = EFAULT; else if (args->val3_compare == true && uval != args->val3) error = EWOULDBLOCK; umtxq_lock(&key); umtxq_unbusy(&key); if (error == 0) { umtxq_lock(&key2); td->td_retval[0] = umtxq_requeue(&key, nrwake, &key2, nrrequeue); umtxq_unlock(&key2); } umtxq_unlock(&key); umtx_key_release(&key2); umtx_key_release(&key); return (error); } static int linux_futex_wake(struct thread *td, struct linux_futex_args *args) { struct umtx_key key; int error; if (args->val3 == 0) return (EINVAL); error = futex_key_get(args->uaddr, TYPE_FUTEX, GET_SHARED(args), &key); if (error != 0) return (error); umtxq_lock(&key); td->td_retval[0] = umtxq_signal_mask(&key, args->val, args->val3); umtxq_unlock(&key); umtx_key_release(&key); return (0); } static int linux_futex_wait(struct thread *td, struct linux_futex_args *args) { struct umtx_abs_timeout timo; struct umtx_q *uq; uint32_t uval; int error; if (args->val3 == 0) error = EINVAL; uq = td->td_umtxq; error = futex_key_get(args->uaddr, TYPE_FUTEX, GET_SHARED(args), &uq->uq_key); if (error != 0) return (error); if (args->ts != NULL) linux_umtx_abs_timeout_init(&timo, args); umtxq_lock(&uq->uq_key); umtxq_busy(&uq->uq_key); uq->uq_bitset = args->val3; umtxq_insert(uq); umtxq_unlock(&uq->uq_key); error = fueword32(args->uaddr, &uval); if (error != 0) error = EFAULT; else if (uval != args->val) error = EWOULDBLOCK; umtxq_lock(&uq->uq_key); umtxq_unbusy(&uq->uq_key); if (error == 0) { error = umtxq_sleep(uq, "futex", args->ts == NULL ? NULL : &timo); if ((uq->uq_flags & UQF_UMTXQ) == 0) error = 0; else umtxq_remove(uq); } else if ((uq->uq_flags & UQF_UMTXQ) != 0) { umtxq_remove(uq); } umtxq_unlock(&uq->uq_key); umtx_key_release(&uq->uq_key); if (error == ERESTART) error = EINTR; return (error); } static void linux_umtx_abs_timeout_init(struct umtx_abs_timeout *timo, struct linux_futex_args *args) { int clockid, absolute; /* * The FUTEX_CLOCK_REALTIME option bit can be employed only with the * FUTEX_WAIT_BITSET, FUTEX_WAIT_REQUEUE_PI, FUTEX_LOCK_PI2. * For FUTEX_WAIT, timeout is interpreted as a relative value, for other * futex operations timeout is interpreted as an absolute value. * If FUTEX_CLOCK_REALTIME option bit is set, the Linux kernel measures * the timeout against the CLOCK_REALTIME clock, otherwise the kernel * measures the timeout against the CLOCK_MONOTONIC clock. */ clockid = args->clockrt ? CLOCK_REALTIME : CLOCK_MONOTONIC; absolute = args->op == LINUX_FUTEX_WAIT ? false : true; umtx_abs_timeout_init(timo, clockid, absolute, args->ts); } int linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args) { struct linux_futex_args fargs = { .uaddr = args->uaddr, .op = args->op, .val = args->val, .ts = NULL, .uaddr2 = args->uaddr2, .val3 = args->val3, .val3_compare = true, }; int error; switch (args->op & LINUX_FUTEX_CMD_MASK) { case LINUX_FUTEX_WAIT: case LINUX_FUTEX_WAIT_BITSET: case LINUX_FUTEX_LOCK_PI: case LINUX_FUTEX_LOCK_PI2: if (args->timeout != NULL) { error = linux_get_timespec(&fargs.kts, args->timeout); if (error != 0) return (error); fargs.ts = &fargs.kts; } break; default: fargs.ts = PTRIN(args->timeout); } return (linux_futex(td, &fargs)); } #if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32)) int linux_sys_futex_time64(struct thread *td, struct linux_sys_futex_time64_args *args) { struct linux_futex_args fargs = { .uaddr = args->uaddr, .op = args->op, .val = args->val, .ts = NULL, .uaddr2 = args->uaddr2, .val3 = args->val3, .val3_compare = true, }; int error; switch (args->op & LINUX_FUTEX_CMD_MASK) { case LINUX_FUTEX_WAIT: case LINUX_FUTEX_WAIT_BITSET: case LINUX_FUTEX_LOCK_PI: case LINUX_FUTEX_LOCK_PI2: if (args->timeout != NULL) { error = linux_get_timespec64(&fargs.kts, args->timeout); if (error != 0) return (error); fargs.ts = &fargs.kts; } break; default: fargs.ts = PTRIN(args->timeout); } return (linux_futex(td, &fargs)); } #endif int linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args) { struct linux_emuldata *em; if (args->len != sizeof(struct linux_robust_list_head)) return (EINVAL); em = em_find(td); em->robust_futexes = args->head; return (0); } int linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args) { struct linux_emuldata *em; struct linux_robust_list_head *head; l_size_t len; struct thread *td2; int error; if (!args->pid) { em = em_find(td); KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n")); head = em->robust_futexes; } else { td2 = linux_tdfind(td, args->pid, -1); if (td2 == NULL) return (ESRCH); if (SV_PROC_ABI(td2->td_proc) != SV_ABI_LINUX) { PROC_UNLOCK(td2->td_proc); return (EPERM); } em = em_find(td2); KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n")); /* XXX: ptrace? */ if (priv_check(td, PRIV_CRED_SETUID) || priv_check(td, PRIV_CRED_SETEUID) || p_candebug(td, td2->td_proc)) { PROC_UNLOCK(td2->td_proc); return (EPERM); } head = em->robust_futexes; PROC_UNLOCK(td2->td_proc); } len = sizeof(struct linux_robust_list_head); error = copyout(&len, args->len, sizeof(l_size_t)); if (error != 0) return (EFAULT); return (copyout(&head, args->head, sizeof(l_uintptr_t))); } static int handle_futex_death(struct thread *td, struct linux_emuldata *em, uint32_t *uaddr, unsigned int pi, bool pending_op) { uint32_t uval, nval, mval; int error; retry: error = fueword32(uaddr, &uval); if (error != 0) return (EFAULT); /* * Special case for regular (non PI) futexes. The unlock path in * user space has two race scenarios: * * 1. The unlock path releases the user space futex value and * before it can execute the futex() syscall to wake up * waiters it is killed. * * 2. A woken up waiter is killed before it can acquire the * futex in user space. * * In both cases the TID validation below prevents a wakeup of * potential waiters which can cause these waiters to block * forever. * * In both cases it is safe to attempt waking up a potential * waiter without touching the user space futex value and trying * to set the OWNER_DIED bit. */ if (pending_op && !pi && !uval) { (void)futex_wake(td, uaddr, 1, true); return (0); } if ((uval & FUTEX_TID_MASK) == em->em_tid) { mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; error = casueword32(uaddr, uval, &nval, mval); if (error == -1) return (EFAULT); if (error == 1) { error = thread_check_susp(td, false); if (error != 0) return (error); goto retry; } if (!pi && (uval & FUTEX_WAITERS)) { error = futex_wake(td, uaddr, 1, true); if (error != 0) return (error); } else if (pi && (uval & FUTEX_WAITERS)) { error = futex_wake_pi(td, uaddr, true); if (error != 0) return (error); } } return (0); } static int fetch_robust_entry(struct linux_robust_list **entry, struct linux_robust_list **head, unsigned int *pi) { l_ulong uentry; int error; error = copyin((const void *)head, &uentry, sizeof(uentry)); if (error != 0) return (EFAULT); *entry = (void *)(uentry & ~1UL); *pi = uentry & 1; return (0); } #define LINUX_HANDLE_DEATH_PENDING true #define LINUX_HANDLE_DEATH_LIST false /* This walks the list of robust futexes releasing them. */ void release_futexes(struct thread *td, struct linux_emuldata *em) { struct linux_robust_list_head *head; struct linux_robust_list *entry, *next_entry, *pending; unsigned int limit = 2048, pi, next_pi, pip; uint32_t *uaddr; l_long futex_offset; int error; head = em->robust_futexes; if (head == NULL) return; if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) return; error = copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset)); if (error != 0) return; if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) return; while (entry != &head->list) { error = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi); /* * A pending lock might already be on the list, so * don't process it twice. */ if (entry != pending) { uaddr = (uint32_t *)((caddr_t)entry + futex_offset); if (handle_futex_death(td, em, uaddr, pi, LINUX_HANDLE_DEATH_LIST)) return; } if (error != 0) return; entry = next_entry; pi = next_pi; if (!--limit) break; sched_relinquish(curthread); } if (pending) { uaddr = (uint32_t *)((caddr_t)pending + futex_offset); (void)handle_futex_death(td, em, uaddr, pip, LINUX_HANDLE_DEATH_PENDING); } }