| /* Copyright (C) 2005-2021 Free Software Foundation, Inc. |
| Contributed by Richard Henderson <rth@redhat.com>. |
| |
| This file is part of the GNU Offloading and Multi Processing Library |
| (libgomp). |
| |
| Libgomp 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 3, or (at your option) |
| any later version. |
| |
| Libgomp 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. |
| |
| Under Section 7 of GPL version 3, you are granted additional |
| permissions described in the GCC Runtime Library Exception, version |
| 3.1, as published by the Free Software Foundation. |
| |
| You should have received a copy of the GNU General Public License and |
| a copy of the GCC Runtime Library Exception along with this program; |
| see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| /* This is a Linux specific implementation of the public OpenMP locking |
| primitives. This implementation uses atomic instructions and the futex |
| syscall. */ |
| |
| #include <string.h> |
| #include <unistd.h> |
| #include <sys/syscall.h> |
| #include "wait.h" |
| |
| /* Reuse the generic implementation in terms of gomp_mutex_t. */ |
| #include "../../lock.c" |
| |
| #ifdef LIBGOMP_GNU_SYMBOL_VERSIONING |
| /* gomp_mutex_* can be safely locked in one thread and |
| unlocked in another thread, so the OpenMP 2.5 and OpenMP 3.0 |
| non-nested locks can be the same. */ |
| strong_alias (gomp_init_lock_30, gomp_init_lock_25) |
| strong_alias (gomp_destroy_lock_30, gomp_destroy_lock_25) |
| strong_alias (gomp_set_lock_30, gomp_set_lock_25) |
| strong_alias (gomp_unset_lock_30, gomp_unset_lock_25) |
| strong_alias (gomp_test_lock_30, gomp_test_lock_25) |
| |
| /* The external recursive omp_nest_lock_25_t form requires additional work. */ |
| |
| /* We need an integer to uniquely identify this thread. Most generally |
| this is the thread's TID, which ideally we'd get this straight from |
| the TLS block where glibc keeps it. Unfortunately, we can't get at |
| that directly. |
| |
| If we don't support (or have disabled) TLS, one function call is as |
| good (or bad) as any other. Use the syscall all the time. |
| |
| On an ILP32 system (defined here as not LP64), we can make do with |
| any thread-local pointer. Ideally we'd use the TLS base address, |
| since that requires the least amount of arithmetic, but that's not |
| always available directly. Make do with the gomp_thread pointer |
| since it's handy. */ |
| |
| # if !defined (HAVE_TLS) |
| static inline int gomp_tid (void) |
| { |
| return syscall (SYS_gettid); |
| } |
| # elif !defined(__LP64__) |
| static inline int gomp_tid (void) |
| { |
| return (int) gomp_thread (); |
| } |
| # else |
| static __thread int tid_cache; |
| static inline int gomp_tid (void) |
| { |
| int tid = tid_cache; |
| if (__builtin_expect (tid == 0, 0)) |
| tid_cache = tid = syscall (SYS_gettid); |
| return tid; |
| } |
| # endif |
| |
| |
| void |
| gomp_init_nest_lock_25 (omp_nest_lock_25_t *lock) |
| { |
| memset (lock, 0, sizeof (*lock)); |
| } |
| |
| void |
| gomp_destroy_nest_lock_25 (omp_nest_lock_25_t *lock) |
| { |
| } |
| |
| void |
| gomp_set_nest_lock_25 (omp_nest_lock_25_t *lock) |
| { |
| int otid, tid = gomp_tid (); |
| |
| while (1) |
| { |
| otid = 0; |
| if (__atomic_compare_exchange_n (&lock->owner, &otid, tid, false, |
| MEMMODEL_ACQUIRE, MEMMODEL_RELAXED)) |
| { |
| lock->count = 1; |
| return; |
| } |
| if (otid == tid) |
| { |
| lock->count++; |
| return; |
| } |
| |
| do_wait (&lock->owner, otid); |
| } |
| } |
| |
| void |
| gomp_unset_nest_lock_25 (omp_nest_lock_25_t *lock) |
| { |
| /* ??? Validate that we own the lock here. */ |
| |
| if (--lock->count == 0) |
| { |
| __atomic_store_n (&lock->owner, 0, MEMMODEL_RELEASE); |
| futex_wake (&lock->owner, 1); |
| } |
| } |
| |
| int |
| gomp_test_nest_lock_25 (omp_nest_lock_25_t *lock) |
| { |
| int otid, tid = gomp_tid (); |
| |
| otid = 0; |
| if (__atomic_compare_exchange_n (&lock->owner, &otid, tid, false, |
| MEMMODEL_ACQUIRE, MEMMODEL_RELAXED)) |
| { |
| lock->count = 1; |
| return 1; |
| } |
| if (otid == tid) |
| return ++lock->count; |
| |
| return 0; |
| } |
| |
| omp_lock_symver (omp_init_lock) |
| omp_lock_symver (omp_destroy_lock) |
| omp_lock_symver (omp_set_lock) |
| omp_lock_symver (omp_unset_lock) |
| omp_lock_symver (omp_test_lock) |
| omp_lock_symver (omp_init_nest_lock) |
| omp_lock_symver (omp_destroy_nest_lock) |
| omp_lock_symver (omp_set_nest_lock) |
| omp_lock_symver (omp_unset_nest_lock) |
| omp_lock_symver (omp_test_nest_lock) |
| |
| #else |
| |
| ialias (omp_init_lock) |
| ialias (omp_init_nest_lock) |
| ialias (omp_destroy_lock) |
| ialias (omp_destroy_nest_lock) |
| ialias (omp_set_lock) |
| ialias (omp_set_nest_lock) |
| ialias (omp_unset_lock) |
| ialias (omp_unset_nest_lock) |
| ialias (omp_test_lock) |
| ialias (omp_test_nest_lock) |
| |
| #endif |