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1 /* Copyright (C) 2014-2017 Free Software Foundation, Inc.
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2 Contributed by Kai Tietz <ktietz@redhat.com>.
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3
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4 This file is part of the GNU Atomic Library (libatomic).
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5
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6 Libatomic is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3 of the License, or
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9 (at your option) any later version.
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10
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11 Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
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12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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14 more details.
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15
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16 Under Section 7 of GPL version 3, you are granted additional
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17 permissions described in the GCC Runtime Library Exception, version
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18 3.1, as published by the Free Software Foundation.
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19
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20 You should have received a copy of the GNU General Public License and
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21 a copy of the GCC Runtime Library Exception along with this program;
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22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 <http://www.gnu.org/licenses/>. */
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24
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25 #define UWORD __shadow_UWORD
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26 #include <windows.h>
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27 #undef UWORD
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28 #include "libatomic_i.h"
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29
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30 /* The target page size. Must be no larger than the runtime page size,
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31 lest locking fail with virtual address aliasing (i.e. a page mmaped
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32 at two locations). */
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33 #ifndef PAGE_SIZE
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34 #define PAGE_SIZE 4096
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35 #endif
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36
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37 /* The target cacheline size. This is an optimization; the padding that
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38 should be applied to the locks to keep them from interfering. */
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39 #ifndef CACHLINE_SIZE
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40 #define CACHLINE_SIZE 64
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41 #endif
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42
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43 /* The granularity at which locks are applied. Almost certainly the
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44 cachline size is the right thing to use here. */
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45 #ifndef WATCH_SIZE
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46 #define WATCH_SIZE CACHLINE_SIZE
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47 #endif
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48
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49 struct lock
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50 {
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51 HANDLE mutex;
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52 char pad[sizeof (HANDLE) < CACHLINE_SIZE
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53 ? CACHLINE_SIZE - sizeof (HANDLE)
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54 : 0];
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55 };
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56
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57 #define NLOCKS (PAGE_SIZE / WATCH_SIZE)
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58
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59 static struct lock locks[NLOCKS] = {
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60 [0 ... NLOCKS-1].mutex = NULL
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61 };
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62
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63 static inline uintptr_t
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64 addr_hash (void *ptr)
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65 {
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66 return ((uintptr_t)ptr / WATCH_SIZE) % NLOCKS;
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67 }
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68
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69 void
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70 libat_lock_1 (void *ptr)
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71 {
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72 if (!locks[addr_hash (ptr)].mutex)
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73 locks[addr_hash (ptr)].mutex = CreateMutex (NULL, FALSE, NULL);
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74 WaitForSingleObject (locks[addr_hash (ptr)].mutex, INFINITE);
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75 }
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76
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77 void
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78 libat_unlock_1 (void *ptr)
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79 {
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80 if (locks[addr_hash (ptr)].mutex)
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81 ReleaseMutex (locks[addr_hash (ptr)].mutex);
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82 }
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83
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84 void
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85 libat_lock_n (void *ptr, size_t n)
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86 {
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87 uintptr_t h = addr_hash (ptr);
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88 size_t i = 0;
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89
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90 /* Don't lock more than all the locks we have. */
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91 if (n > PAGE_SIZE)
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92 n = PAGE_SIZE;
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93
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94 do
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95 {
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96 if (!locks[h].mutex)
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97 locks[h].mutex = CreateMutex (NULL, FALSE, NULL);
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98 WaitForSingleObject (locks[h].mutex, INFINITE);
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99 if (++h == NLOCKS)
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100 h = 0;
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101 i += WATCH_SIZE;
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102 }
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103 while (i < n);
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104 }
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105
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106 void
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107 libat_unlock_n (void *ptr, size_t n)
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108 {
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109 uintptr_t h = addr_hash (ptr);
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110 size_t i = 0;
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111
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112 if (n > PAGE_SIZE)
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113 n = PAGE_SIZE;
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114
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115 do
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116 {
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117 if (locks[h].mutex)
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118 ReleaseMutex (locks[h].mutex);
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119 if (++h == NLOCKS)
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120 h = 0;
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121 i += WATCH_SIZE;
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122 }
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123 while (i < n);
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124 }
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