1 /* atomic.c -- Support for atomic functions if not present. 2 Copyright (C) 2013-2019 Free Software Foundation, Inc. 3 Written by Ian Lance Taylor, Google. 4 5 Redistribution and use in source and binary forms, with or without 6 modification, are permitted provided that the following conditions are 7 met: 8 9 (1) Redistributions of source code must retain the above copyright 10 notice, this list of conditions and the following disclaimer. 11 12 (2) Redistributions in binary form must reproduce the above copyright 13 notice, this list of conditions and the following disclaimer in 14 the documentation and/or other materials provided with the 15 distribution. 16 17 (3) The name of the author may not be used to 18 endorse or promote products derived from this software without 19 specific prior written permission. 20 21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 24 DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, 25 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 26 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 27 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 29 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 30 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31 POSSIBILITY OF SUCH DAMAGE. */ 32 33 #include "config.h" 34 35 #include <sys/types.h> 36 37 #include "backtrace.h" 38 #include "backtrace-supported.h" 39 #include "internal.h" 40 41 /* This file holds implementations of the atomic functions that are 42 used if the host compiler has the sync functions but not the atomic 43 functions, as is true of versions of GCC before 4.7. */ 44 45 #if !defined (HAVE_ATOMIC_FUNCTIONS) && defined (HAVE_SYNC_FUNCTIONS) 46 47 /* Do an atomic load of a pointer. */ 48 49 void * 50 backtrace_atomic_load_pointer (void *arg) 51 { 52 void **pp; 53 void *p; 54 55 pp = (void **) arg; 56 p = *pp; 57 while (!__sync_bool_compare_and_swap (pp, p, p)) 58 p = *pp; 59 return p; 60 } 61 62 /* Do an atomic load of an int. */ 63 64 int 65 backtrace_atomic_load_int (int *p) 66 { 67 int i; 68 69 i = *p; 70 while (!__sync_bool_compare_and_swap (p, i, i)) 71 i = *p; 72 return i; 73 } 74 75 /* Do an atomic store of a pointer. */ 76 77 void 78 backtrace_atomic_store_pointer (void *arg, void *p) 79 { 80 void **pp; 81 void *old; 82 83 pp = (void **) arg; 84 old = *pp; 85 while (!__sync_bool_compare_and_swap (pp, old, p)) 86 old = *pp; 87 } 88 89 /* Do an atomic store of a size_t value. */ 90 91 void 92 backtrace_atomic_store_size_t (size_t *p, size_t v) 93 { 94 size_t old; 95 96 old = *p; 97 while (!__sync_bool_compare_and_swap (p, old, v)) 98 old = *p; 99 } 100 101 /* Do an atomic store of a int value. */ 102 103 void 104 backtrace_atomic_store_int (int *p, int v) 105 { 106 size_t old; 107 108 old = *p; 109 while (!__sync_bool_compare_and_swap (p, old, v)) 110 old = *p; 111 } 112 113 #endif 114