1 /* 2 * Copyright (c) 2008, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef OS_CPU_LINUX_ARM_VM_ORDERACCESS_LINUX_ARM_INLINE_HPP 26 #define OS_CPU_LINUX_ARM_VM_ORDERACCESS_LINUX_ARM_INLINE_HPP 27 28 #include "runtime/orderAccess.hpp" 29 #include "runtime/os.hpp" 30 #include "vm_version_arm.hpp" 31 32 // Implementation of class OrderAccess. 33 // - we define the high level barriers below and use the general 34 // implementation in orderAccess.inline.hpp, with customizations 35 // on AARCH64 via the specialized_* template functions 36 37 // Memory Ordering on ARM is weak. 38 // 39 // Implement all 4 memory ordering barriers by DMB, since it is a 40 // lighter version of DSB. 41 // dmb_sy implies full system shareability domain. RD/WR access type. 42 // dmb_st implies full system shareability domain. WR only access type. 43 // 44 // NOP on < ARMv6 (MP not supported) 45 // 46 // Non mcr instructions can be used if we build for armv7 or higher arch 47 // __asm__ __volatile__ ("dmb" : : : "memory"); 48 // __asm__ __volatile__ ("dsb" : : : "memory"); 49 // 50 // inline void _OrderAccess_dsb() { 51 // volatile intptr_t dummy = 0; 52 // if (os::is_MP()) { 53 // __asm__ volatile ( 54 // "mcr p15, 0, %0, c7, c10, 4" 55 // : : "r" (dummy) : "memory"); 56 // } 57 // } 58 59 inline static void dmb_sy() { 60 if (!os::is_MP()) { 61 return; 62 } 63 #ifdef AARCH64 64 __asm__ __volatile__ ("dmb sy" : : : "memory"); 65 #else 66 if (VM_Version::arm_arch() >= 7) { 67 #ifdef __thumb__ 68 __asm__ volatile ( 69 "dmb sy": : : "memory"); 70 #else 71 __asm__ volatile ( 72 ".word 0xF57FF050 | 0xf" : : : "memory"); 73 #endif 74 } else { 75 intptr_t zero = 0; 76 __asm__ volatile ( 77 "mcr p15, 0, %0, c7, c10, 5" 78 : : "r" (zero) : "memory"); 79 } 80 #endif 81 } 82 83 inline static void dmb_st() { 84 if (!os::is_MP()) { 85 return; 86 } 87 #ifdef AARCH64 88 __asm__ __volatile__ ("dmb st" : : : "memory"); 89 #else 90 if (VM_Version::arm_arch() >= 7) { 91 #ifdef __thumb__ 92 __asm__ volatile ( 93 "dmb st": : : "memory"); 94 #else 95 __asm__ volatile ( 96 ".word 0xF57FF050 | 0xe" : : : "memory"); 97 #endif 98 } else { 99 intptr_t zero = 0; 100 __asm__ volatile ( 101 "mcr p15, 0, %0, c7, c10, 5" 102 : : "r" (zero) : "memory"); 103 } 104 #endif 105 } 106 107 // Load-Load/Store barrier 108 inline static void dmb_ld() { 109 #ifdef AARCH64 110 if (!os::is_MP()) { 111 return; 112 } 113 __asm__ __volatile__ ("dmb ld" : : : "memory"); 114 #else 115 dmb_sy(); 116 #endif 117 } 118 119 120 inline void OrderAccess::loadload() { dmb_ld(); } 121 inline void OrderAccess::loadstore() { dmb_ld(); } 122 inline void OrderAccess::acquire() { dmb_ld(); } 123 inline void OrderAccess::storestore() { dmb_st(); } 124 inline void OrderAccess::storeload() { dmb_sy(); } 125 inline void OrderAccess::release() { dmb_sy(); } 126 inline void OrderAccess::fence() { dmb_sy(); } 127 128 // specializations for Aarch64 129 // TODO-AARCH64: evaluate effectiveness of ldar*/stlr* implementations compared to 32-bit ARM approach 130 131 #ifdef AARCH64 132 133 template<> 134 struct OrderAccess::PlatformOrderedLoad<1, X_ACQUIRE> 135 VALUE_OBJ_CLASS_SPEC 136 { 137 template <typename T> 138 T operator()(const volatile T* p) const { 139 volatile T result; 140 __asm__ volatile( 141 "ldarb %w[res], [%[ptr]]" 142 : [res] "=&r" (result) 143 : [ptr] "r" (p) 144 : "memory"); 145 return result; 146 } 147 }; 148 149 template<> 150 struct OrderAccess::PlatformOrderedLoad<2, X_ACQUIRE> 151 VALUE_OBJ_CLASS_SPEC 152 { 153 template <typename T> 154 T operator()(const volatile T* p) const { 155 volatile T result; 156 __asm__ volatile( 157 "ldarh %w[res], [%[ptr]]" 158 : [res] "=&r" (result) 159 : [ptr] "r" (p) 160 : "memory"); 161 return result; 162 } 163 }; 164 165 template<> 166 struct OrderAccess::PlatformOrderedLoad<4, X_ACQUIRE> 167 VALUE_OBJ_CLASS_SPEC 168 { 169 template <typename T> 170 T operator()(const volatile T* p) const { 171 volatile T result; 172 __asm__ volatile( 173 "ldar %w[res], [%[ptr]]" 174 : [res] "=&r" (result) 175 : [ptr] "r" (p) 176 : "memory"); 177 return result; 178 } 179 }; 180 181 template<> 182 struct OrderAccess::PlatformOrderedLoad<8, X_ACQUIRE> 183 VALUE_OBJ_CLASS_SPEC 184 { 185 template <typename T> 186 T operator()(const volatile T* p) const { 187 volatile T result; 188 __asm__ volatile( 189 "ldar %[res], [%[ptr]]" 190 : [res] "=&r" (result) 191 : [ptr] "r" (p) 192 : "memory"); 193 return result; 194 } 195 }; 196 197 template<> 198 struct OrderAccess::PlatformOrderedStore<1, RELEASE_X_FENCE> 199 VALUE_OBJ_CLASS_SPEC 200 { 201 template <typename T> 202 void operator()(T v, volatile T* p) const { 203 __asm__ volatile( 204 "stlrb %w[val], [%[ptr]]" 205 : 206 : [ptr] "r" (p), [val] "r" (v) 207 : "memory"); 208 } 209 }; 210 211 template<> 212 struct OrderAccess::PlatformOrderedStore<2, RELEASE_X_FENCE> 213 VALUE_OBJ_CLASS_SPEC 214 { 215 template <typename T> 216 void operator()(T v, volatile T* p) const { 217 __asm__ volatile( 218 "stlrh %w[val], [%[ptr]]" 219 : 220 : [ptr] "r" (p), [val] "r" (v) 221 : "memory"); 222 } 223 }; 224 225 template<> 226 struct OrderAccess::PlatformOrderedStore<4, RELEASE_X_FENCE> 227 VALUE_OBJ_CLASS_SPEC 228 { 229 template <typename T> 230 void operator()(T v, volatile T* p) const { 231 __asm__ volatile( 232 "stlr %w[val], [%[ptr]]" 233 : 234 : [ptr] "r" (p), [val] "r" (v) 235 : "memory"); 236 } 237 }; 238 239 template<> 240 struct OrderAccess::PlatformOrderedStore<8, RELEASE_X_FENCE> 241 VALUE_OBJ_CLASS_SPEC 242 { 243 template <typename T> 244 void operator()(T v, volatile T* p) const { 245 __asm__ volatile( 246 "stlr %[val], [%[ptr]]" 247 : 248 : [ptr] "r" (p), [val] "r" (v) 249 : "memory"); 250 } 251 }; 252 253 #endif // AARCH64 254 255 #endif // OS_CPU_LINUX_ARM_VM_ORDERACCESS_LINUX_ARM_INLINE_HPP