1 // Implementation of synchronization functions for ARM architecture (AArch64) 2 // 3 // Copyright (c) 2012-2015, ARM Limited. All rights reserved. 4 // Copyright (c) 2015, Linaro Limited. All rights reserved. 5 // 6 // This program and the accompanying materials 7 // are licensed and made available under the terms and conditions of the BSD License 8 // which accompanies this distribution. The full text of the license may be found at 9 // http://opensource.org/licenses/bsd-license.php 10 // 11 // THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 13 // 14 // 15 16 .text 17 .align 3 18 19 GCC_ASM_EXPORT(InternalSyncCompareExchange16) 20 GCC_ASM_EXPORT(InternalSyncCompareExchange32) 21 GCC_ASM_EXPORT(InternalSyncCompareExchange64) 22 GCC_ASM_EXPORT(InternalSyncIncrement) 23 GCC_ASM_EXPORT(InternalSyncDecrement) 24 25 /** 26 Performs an atomic compare exchange operation on a 16-bit unsigned integer. 27 28 Performs an atomic compare exchange operation on the 16-bit unsigned integer 29 specified by Value. If Value is equal to CompareValue, then Value is set to 30 ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue, 31 then Value is returned. The compare exchange operation must be performed using 32 MP safe mechanisms. 33 34 @param Value A pointer to the 16-bit value for the compare exchange 35 operation. 36 @param CompareValue 16-bit value used in compare operation. 37 @param ExchangeValue 16-bit value used in exchange operation. 38 39 @return The original *Value before exchange. 40 41 **/ 42 //UINT16 43 //EFIAPI 44 //InternalSyncCompareExchange16 ( 45 // IN volatile UINT16 *Value, 46 // IN UINT16 CompareValue, 47 // IN UINT16 ExchangeValue 48 // ) 49 ASM_PFX(InternalSyncCompareExchange16): 50 uxth w1, w1 51 uxth w2, w2 52 dmb sy 53 54 InternalSyncCompareExchange16Again: 55 ldxrh w3, [x0] 56 cmp w3, w1 57 bne InternalSyncCompareExchange16Fail 58 59 InternalSyncCompareExchange16Exchange: 60 stxrh w4, w2, [x0] 61 cbnz w4, InternalSyncCompareExchange16Again 62 63 InternalSyncCompareExchange16Fail: 64 dmb sy 65 mov w0, w3 66 ret 67 68 /** 69 Performs an atomic compare exchange operation on a 32-bit unsigned integer. 70 71 Performs an atomic compare exchange operation on the 32-bit unsigned integer 72 specified by Value. If Value is equal to CompareValue, then Value is set to 73 ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue, 74 then Value is returned. The compare exchange operation must be performed using 75 MP safe mechanisms. 76 77 @param Value A pointer to the 32-bit value for the compare exchange 78 operation. 79 @param CompareValue 32-bit value used in compare operation. 80 @param ExchangeValue 32-bit value used in exchange operation. 81 82 @return The original *Value before exchange. 83 84 **/ 85 //UINT32 86 //EFIAPI 87 //InternalSyncCompareExchange32 ( 88 // IN volatile UINT32 *Value, 89 // IN UINT32 CompareValue, 90 // IN UINT32 ExchangeValue 91 // ) 92 ASM_PFX(InternalSyncCompareExchange32): 93 dmb sy 94 95 InternalSyncCompareExchange32Again: 96 ldxr w3, [x0] 97 cmp w3, w1 98 bne InternalSyncCompareExchange32Fail 99 100 InternalSyncCompareExchange32Exchange: 101 stxr w4, w2, [x0] 102 cbnz w4, InternalSyncCompareExchange32Again 103 104 InternalSyncCompareExchange32Fail: 105 dmb sy 106 mov w0, w3 107 ret 108 109 /** 110 Performs an atomic compare exchange operation on a 64-bit unsigned integer. 111 112 Performs an atomic compare exchange operation on the 64-bit unsigned integer specified 113 by Value. If Value is equal to CompareValue, then Value is set to ExchangeValue and 114 CompareValue is returned. If Value is not equal to CompareValue, then Value is returned. 115 The compare exchange operation must be performed using MP safe mechanisms. 116 117 @param Value A pointer to the 64-bit value for the compare exchange 118 operation. 119 @param CompareValue 64-bit value used in compare operation. 120 @param ExchangeValue 64-bit value used in exchange operation. 121 122 @return The original *Value before exchange. 123 124 **/ 125 //UINT64 126 //EFIAPI 127 //InternalSyncCompareExchange64 ( 128 // IN volatile UINT64 *Value, 129 // IN UINT64 CompareValue, 130 // IN UINT64 ExchangeValue 131 // ) 132 ASM_PFX(InternalSyncCompareExchange64): 133 dmb sy 134 135 InternalSyncCompareExchange64Again: 136 ldxr x3, [x0] 137 cmp x3, x1 138 bne InternalSyncCompareExchange64Fail 139 140 InternalSyncCompareExchange64Exchange: 141 stxr w4, x2, [x0] 142 cbnz w4, InternalSyncCompareExchange64Again 143 144 InternalSyncCompareExchange64Fail: 145 dmb sy 146 mov x0, x3 147 ret 148 149 /** 150 Performs an atomic increment of an 32-bit unsigned integer. 151 152 Performs an atomic increment of the 32-bit unsigned integer specified by 153 Value and returns the incremented value. The increment operation must be 154 performed using MP safe mechanisms. The state of the return value is not 155 guaranteed to be MP safe. 156 157 @param Value A pointer to the 32-bit value to increment. 158 159 @return The incremented value. 160 161 **/ 162 //UINT32 163 //EFIAPI 164 //InternalSyncIncrement ( 165 // IN volatile UINT32 *Value 166 // ) 167 ASM_PFX(InternalSyncIncrement): 168 dmb sy 169 TryInternalSyncIncrement: 170 ldxr w1, [x0] 171 add w1, w1, #1 172 stxr w2, w1, [x0] 173 cbnz w2, TryInternalSyncIncrement 174 mov w0, w1 175 dmb sy 176 ret 177 178 /** 179 Performs an atomic decrement of an 32-bit unsigned integer. 180 181 Performs an atomic decrement of the 32-bit unsigned integer specified by 182 Value and returns the decrement value. The decrement operation must be 183 performed using MP safe mechanisms. The state of the return value is not 184 guaranteed to be MP safe. 185 186 @param Value A pointer to the 32-bit value to decrement. 187 188 @return The decrement value. 189 190 **/ 191 //UINT32 192 //EFIAPI 193 //InternalSyncDecrement ( 194 // IN volatile UINT32 *Value 195 // ) 196 ASM_PFX(InternalSyncDecrement): 197 dmb sy 198 TryInternalSyncDecrement: 199 ldxr w1, [x0] 200 sub w1, w1, #1 201 stxr w2, w1, [x0] 202 cbnz w2, TryInternalSyncDecrement 203 mov w0, w1 204 dmb sy 205 ret 206
