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fbd26352 | 1 | /* Copyright (C) 2008-2019 Free Software Foundation, Inc. |
fd6481cf | 2 | Contributed by Jakub Jelinek <jakub@redhat.com>. |
3 | ||
c35c9a62 | 4 | This file is part of the GNU Offloading and Multi Processing Library |
5 | (libgomp). | |
fd6481cf | 6 | |
7 | Libgomp is free software; you can redistribute it and/or modify it | |
6bc9506f | 8 | under the terms of the GNU General Public License as published by |
9 | the Free Software Foundation; either version 3, or (at your option) | |
10 | any later version. | |
fd6481cf | 11 | |
12 | Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
6bc9506f | 14 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
fd6481cf | 15 | more details. |
16 | ||
6bc9506f | 17 | Under Section 7 of GPL version 3, you are granted additional |
18 | permissions described in the GCC Runtime Library Exception, version | |
19 | 3.1, as published by the Free Software Foundation. | |
fd6481cf | 20 | |
6bc9506f | 21 | You should have received a copy of the GNU General Public License and |
22 | a copy of the GCC Runtime Library Exception along with this program; | |
23 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
24 | <http://www.gnu.org/licenses/>. */ | |
fd6481cf | 25 | |
26 | /* This is a Linux specific implementation of a mutex synchronization | |
27 | mechanism for libgomp. This type is private to the library. This | |
28 | implementation uses atomic instructions and the futex syscall. */ | |
29 | ||
30 | #include <endian.h> | |
31 | #include <limits.h> | |
32 | #include "wait.h" | |
33 | ||
34 | void * | |
35 | gomp_ptrlock_get_slow (gomp_ptrlock_t *ptrlock) | |
36 | { | |
37 | int *intptr; | |
9736f4d2 | 38 | uintptr_t oldval = 1; |
39 | ||
40 | __atomic_compare_exchange_n (ptrlock, &oldval, 2, false, | |
41 | MEMMODEL_RELAXED, MEMMODEL_RELAXED); | |
fd6481cf | 42 | |
43 | /* futex works on ints, not pointers. | |
44 | But a valid work share pointer will be at least | |
45 | 8 byte aligned, so it is safe to assume the low | |
46 | 32-bits of the pointer won't contain values 1 or 2. */ | |
47 | __asm volatile ("" : "=r" (intptr) : "0" (ptrlock)); | |
48 | #if __BYTE_ORDER == __BIG_ENDIAN | |
49 | if (sizeof (*ptrlock) > sizeof (int)) | |
50 | intptr += (sizeof (*ptrlock) / sizeof (int)) - 1; | |
51 | #endif | |
52 | do | |
53 | do_wait (intptr, 2); | |
29416343 | 54 | while (__atomic_load_n (intptr, MEMMODEL_RELAXED) == 2); |
fd6481cf | 55 | __asm volatile ("" : : : "memory"); |
29416343 | 56 | return (void *) __atomic_load_n (ptrlock, MEMMODEL_ACQUIRE); |
fd6481cf | 57 | } |
58 | ||
59 | void | |
9736f4d2 | 60 | gomp_ptrlock_set_slow (gomp_ptrlock_t *ptrlock) |
fd6481cf | 61 | { |
62 | int *intptr; | |
63 | ||
fd6481cf | 64 | __asm volatile ("" : "=r" (intptr) : "0" (ptrlock)); |
65 | #if __BYTE_ORDER == __BIG_ENDIAN | |
66 | if (sizeof (*ptrlock) > sizeof (int)) | |
67 | intptr += (sizeof (*ptrlock) / sizeof (int)) - 1; | |
68 | #endif | |
69 | futex_wake (intptr, INT_MAX); | |
70 | } |