| 1 | ///////////////////////////////////////////////////////////////////////// |
| 2 | // |
| 3 | // Copyright (C) 2001-2012 The Bochs Project |
| 4 | // Copyright (C) 2017 Google Inc. |
| 5 | // |
| 6 | // This library is free software; you can redistribute it and/or |
| 7 | // modify it under the terms of the GNU Lesser General Public |
| 8 | // License as published by the Free Software Foundation; either |
| 9 | // version 2.1 of the License, or (at your option) any later version. |
| 10 | // |
| 11 | // This library is distributed in the hope that it will be useful, |
| 12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | // Lesser General Public License for more details. |
| 15 | // |
| 16 | // You should have received a copy of the GNU Lesser General Public |
| 17 | // License along with this library; if not, see |
| 18 | // <https://www.gnu.org/licenses/>. |
| 19 | ///////////////////////////////////////////////////////////////////////// |
| 20 | /* |
| 21 | * flags functions |
| 22 | */ |
| 23 | |
| 24 | #include "qemu/osdep.h" |
| 25 | |
| 26 | #include "panic.h" |
| 27 | #include "cpu.h" |
| 28 | #include "x86_flags.h" |
| 29 | #include "x86.h" |
| 30 | |
| 31 | |
| 32 | /* |
| 33 | * The emulator always encodes flags in the same way as CC_OP_CCMPB + MO_TL. |
| 34 | * While for arithmetic operations ZF/SF/PF are computed from the same value, |
| 35 | * ZF=1 may be inconsistent with PF/SF for arbitrary RFLAGS values so CC_SRC2 |
| 36 | * is used for SF and PF. CC_SRC holds a carry-out vector that is used to |
| 37 | * compute AF, CF and OF. |
| 38 | * |
| 39 | * Compared to the TCG CC_OP codes, this avoids conditionals when converting |
| 40 | * to and from the RFLAGS representation. |
| 41 | * |
| 42 | * The underlying ideas ultimately descend from Bochs, but with significant |
| 43 | * simplifications obtained by storing flags in three words rather than two. |
| 44 | */ |
| 45 | |
| 46 | #define LF_SIGN_BIT (TARGET_LONG_BITS - 1) |
| 47 | |
| 48 | #define LF_BIT_CF (TARGET_LONG_BITS - 1) /* lazy Carry Flag */ |
| 49 | #define LF_BIT_PO (TARGET_LONG_BITS - 2) /* lazy Partial Overflow = CF ^ OF */ |
| 50 | |
| 51 | #define LF_MASK_CF ((target_ulong)0x01 << LF_BIT_CF) |
| 52 | #define LF_MASK_PO ((target_ulong)0x01 << LF_BIT_PO) |
| 53 | |
| 54 | /* ******************* */ |
| 55 | /* OSZAPC */ |
| 56 | /* ******************* */ |
| 57 | |
| 58 | /* |
| 59 | * For arithmetic operations ZF/SF/PF are consistent so DST == SRC2. |
| 60 | * For operations that are not full-word, keep AF in the low byte and shift |
| 61 | * the carries left to place PO and CF in the top two bits. |
| 62 | */ |
| 63 | #define SET_FLAGS_OSZAPC_SIZE(size, lf_carries, lf_result) { \ |
| 64 | env->cc_dst = env->cc_src2 = (target_ulong)(int##size##_t)(lf_result); \ |
| 65 | target_ulong temp = (lf_carries) & MAKE_64BIT_MASK(0, size); \ |
| 66 | temp |= temp << (TARGET_LONG_BITS - (size)); \ |
| 67 | env->cc_src = temp; \ |
| 68 | } |
| 69 | |
| 70 | /* carries, result */ |
| 71 | #define SET_FLAGS_OSZAPC_8(carries, result) \ |
| 72 | SET_FLAGS_OSZAPC_SIZE(8, carries, result) |
| 73 | #define SET_FLAGS_OSZAPC_16(carries, result) \ |
| 74 | SET_FLAGS_OSZAPC_SIZE(16, carries, result) |
| 75 | #define SET_FLAGS_OSZAPC_32(carries, result) \ |
| 76 | SET_FLAGS_OSZAPC_SIZE(32, carries, result) |
| 77 | #ifdef TARGET_X86_64 |
| 78 | #define SET_FLAGS_OSZAPC_64(carries, result) \ |
| 79 | SET_FLAGS_OSZAPC_SIZE(64, carries, result) |
| 80 | #endif |
| 81 | |
| 82 | /* ******************* */ |
| 83 | /* OSZAP */ |
| 84 | /* ******************* */ |
| 85 | /* same as setting OSZAPC, but preserve CF and flip PO if the old value of CF |
| 86 | * did not match the high bit of lf_carries. */ |
| 87 | #define SET_FLAGS_OSZAP_SIZE(size, lf_carries, lf_result) { \ |
| 88 | env->cc_dst = env->cc_src2 = (target_ulong)(int##size##_t)(lf_result); \ |
| 89 | target_ulong temp = (lf_carries) & MAKE_64BIT_MASK(0, size); \ |
| 90 | temp |= temp << (TARGET_LONG_BITS - (size)); \ |
| 91 | target_ulong cf_changed = ((target_long)(env->cc_src ^ temp)) < 0; \ |
| 92 | env->cc_src = temp ^ (cf_changed * (LF_MASK_PO | LF_MASK_CF)); \ |
| 93 | } |
| 94 | |
| 95 | /* carries, result */ |
| 96 | #define SET_FLAGS_OSZAP_8(carries, result) \ |
| 97 | SET_FLAGS_OSZAP_SIZE(8, carries, result) |
| 98 | #define SET_FLAGS_OSZAP_16(carries, result) \ |
| 99 | SET_FLAGS_OSZAP_SIZE(16, carries, result) |
| 100 | #define SET_FLAGS_OSZAP_32(carries, result) \ |
| 101 | SET_FLAGS_OSZAP_SIZE(32, carries, result) |
| 102 | #ifdef TARGET_X86_64 |
| 103 | #define SET_FLAGS_OSZAP_64(carries, result) \ |
| 104 | SET_FLAGS_OSZAP_SIZE(64, carries, result) |
| 105 | #endif |
| 106 | |
| 107 | void SET_FLAGS_OxxxxC(CPUX86State *env, bool new_of, bool new_cf) |
| 108 | { |
| 109 | env->cc_src &= ~(LF_MASK_PO | LF_MASK_CF); |
| 110 | env->cc_src |= (-(target_ulong)new_cf << LF_BIT_PO); |
| 111 | env->cc_src ^= ((target_ulong)new_of << LF_BIT_PO); |
| 112 | } |
| 113 | |
| 114 | #ifdef TARGET_X86_64 |
| 115 | void SET_FLAGS_OSZAPC_SUB64(CPUX86State *env, uint64_t v1, uint64_t v2, |
| 116 | uint64_t diff) |
| 117 | { |
| 118 | SET_FLAGS_OSZAPC_64(SUB_COUT_VEC(v1, v2, diff), diff); |
| 119 | } |
| 120 | #endif |
| 121 | |
| 122 | void SET_FLAGS_OSZAPC_SUB32(CPUX86State *env, uint32_t v1, uint32_t v2, |
| 123 | uint32_t diff) |
| 124 | { |
| 125 | SET_FLAGS_OSZAPC_32(SUB_COUT_VEC(v1, v2, diff), diff); |
| 126 | } |
| 127 | |
| 128 | void SET_FLAGS_OSZAPC_SUB16(CPUX86State *env, uint16_t v1, uint16_t v2, |
| 129 | uint16_t diff) |
| 130 | { |
| 131 | SET_FLAGS_OSZAPC_16(SUB_COUT_VEC(v1, v2, diff), diff); |
| 132 | } |
| 133 | |
| 134 | void SET_FLAGS_OSZAPC_SUB8(CPUX86State *env, uint8_t v1, uint8_t v2, |
| 135 | uint8_t diff) |
| 136 | { |
| 137 | SET_FLAGS_OSZAPC_8(SUB_COUT_VEC(v1, v2, diff), diff); |
| 138 | } |
| 139 | |
| 140 | #ifdef TARGET_X86_64 |
| 141 | void SET_FLAGS_OSZAPC_ADD64(CPUX86State *env, uint64_t v1, uint64_t v2, |
| 142 | uint64_t diff) |
| 143 | { |
| 144 | SET_FLAGS_OSZAPC_64(ADD_COUT_VEC(v1, v2, diff), diff); |
| 145 | } |
| 146 | #endif |
| 147 | |
| 148 | void SET_FLAGS_OSZAPC_ADD32(CPUX86State *env, uint32_t v1, uint32_t v2, |
| 149 | uint32_t diff) |
| 150 | { |
| 151 | SET_FLAGS_OSZAPC_32(ADD_COUT_VEC(v1, v2, diff), diff); |
| 152 | } |
| 153 | |
| 154 | void SET_FLAGS_OSZAPC_ADD16(CPUX86State *env, uint16_t v1, uint16_t v2, |
| 155 | uint16_t diff) |
| 156 | { |
| 157 | SET_FLAGS_OSZAPC_16(ADD_COUT_VEC(v1, v2, diff), diff); |
| 158 | } |
| 159 | |
| 160 | void SET_FLAGS_OSZAPC_ADD8(CPUX86State *env, uint8_t v1, uint8_t v2, |
| 161 | uint8_t diff) |
| 162 | { |
| 163 | SET_FLAGS_OSZAPC_8(ADD_COUT_VEC(v1, v2, diff), diff); |
| 164 | } |
| 165 | |
| 166 | #ifdef TARGET_X86_64 |
| 167 | void SET_FLAGS_OSZAP_SUB64(CPUX86State *env, uint64_t v1, uint64_t v2, |
| 168 | uint64_t diff) |
| 169 | { |
| 170 | SET_FLAGS_OSZAP_64(SUB_COUT_VEC(v1, v2, diff), diff); |
| 171 | } |
| 172 | #endif |
| 173 | |
| 174 | void SET_FLAGS_OSZAP_SUB32(CPUX86State *env, uint32_t v1, uint32_t v2, |
| 175 | uint32_t diff) |
| 176 | { |
| 177 | SET_FLAGS_OSZAP_32(SUB_COUT_VEC(v1, v2, diff), diff); |
| 178 | } |
| 179 | |
| 180 | void SET_FLAGS_OSZAP_SUB16(CPUX86State *env, uint16_t v1, uint16_t v2, |
| 181 | uint16_t diff) |
| 182 | { |
| 183 | SET_FLAGS_OSZAP_16(SUB_COUT_VEC(v1, v2, diff), diff); |
| 184 | } |
| 185 | |
| 186 | void SET_FLAGS_OSZAP_SUB8(CPUX86State *env, uint8_t v1, uint8_t v2, |
| 187 | uint8_t diff) |
| 188 | { |
| 189 | SET_FLAGS_OSZAP_8(SUB_COUT_VEC(v1, v2, diff), diff); |
| 190 | } |
| 191 | |
| 192 | #ifdef TARGET_X86_64 |
| 193 | void SET_FLAGS_OSZAP_ADD64(CPUX86State *env, uint64_t v1, uint64_t v2, |
| 194 | uint64_t diff) |
| 195 | { |
| 196 | SET_FLAGS_OSZAP_64(ADD_COUT_VEC(v1, v2, diff), diff); |
| 197 | } |
| 198 | #endif |
| 199 | |
| 200 | void SET_FLAGS_OSZAP_ADD32(CPUX86State *env, uint32_t v1, uint32_t v2, |
| 201 | uint32_t diff) |
| 202 | { |
| 203 | SET_FLAGS_OSZAP_32(ADD_COUT_VEC(v1, v2, diff), diff); |
| 204 | } |
| 205 | |
| 206 | void SET_FLAGS_OSZAP_ADD16(CPUX86State *env, uint16_t v1, uint16_t v2, |
| 207 | uint16_t diff) |
| 208 | { |
| 209 | SET_FLAGS_OSZAP_16(ADD_COUT_VEC(v1, v2, diff), diff); |
| 210 | } |
| 211 | |
| 212 | void SET_FLAGS_OSZAP_ADD8(CPUX86State *env, uint8_t v1, uint8_t v2, |
| 213 | uint8_t diff) |
| 214 | { |
| 215 | SET_FLAGS_OSZAP_8(ADD_COUT_VEC(v1, v2, diff), diff); |
| 216 | } |
| 217 | |
| 218 | #ifdef TARGET_X86_64 |
| 219 | void SET_FLAGS_OSZAPC_LOGIC64(CPUX86State *env, uint64_t v1, uint64_t v2, |
| 220 | uint64_t diff) |
| 221 | { |
| 222 | SET_FLAGS_OSZAPC_64(0, diff); |
| 223 | } |
| 224 | #endif |
| 225 | |
| 226 | void SET_FLAGS_OSZAPC_LOGIC32(CPUX86State *env, uint32_t v1, uint32_t v2, |
| 227 | uint32_t diff) |
| 228 | { |
| 229 | SET_FLAGS_OSZAPC_32(0, diff); |
| 230 | } |
| 231 | |
| 232 | void SET_FLAGS_OSZAPC_LOGIC16(CPUX86State *env, uint16_t v1, uint16_t v2, |
| 233 | uint16_t diff) |
| 234 | { |
| 235 | SET_FLAGS_OSZAPC_16(0, diff); |
| 236 | } |
| 237 | |
| 238 | void SET_FLAGS_OSZAPC_LOGIC8(CPUX86State *env, uint8_t v1, uint8_t v2, |
| 239 | uint8_t diff) |
| 240 | { |
| 241 | SET_FLAGS_OSZAPC_8(0, diff); |
| 242 | } |
| 243 | |
| 244 | static inline uint32_t get_PF(CPUX86State *env) |
| 245 | { |
| 246 | return (parity8(env->cc_src2) - 1) & CC_P; |
| 247 | } |
| 248 | |
| 249 | static inline uint32_t get_OF(CPUX86State *env) |
| 250 | { |
| 251 | return ((env->cc_src >> (LF_BIT_CF - 11)) + CC_O / 2) & CC_O; |
| 252 | } |
| 253 | |
| 254 | bool get_CF(CPUX86State *env) |
| 255 | { |
| 256 | return ((target_long)env->cc_src) < 0; |
| 257 | } |
| 258 | |
| 259 | void set_CF(CPUX86State *env, bool val) |
| 260 | { |
| 261 | /* If CF changes, flip PO and CF */ |
| 262 | target_ulong temp = -(target_ulong)val; |
| 263 | target_ulong cf_changed = ((target_long)(env->cc_src ^ temp)) < 0; |
| 264 | env->cc_src ^= cf_changed * (LF_MASK_PO | LF_MASK_CF); |
| 265 | } |
| 266 | |
| 267 | static inline uint32_t get_ZF(CPUX86State *env) |
| 268 | { |
| 269 | return env->cc_dst ? 0 : CC_Z; |
| 270 | } |
| 271 | |
| 272 | static inline uint32_t get_SF(CPUX86State *env) |
| 273 | { |
| 274 | return (target_long)env->cc_src2 < 0 ? CC_S : 0; |
| 275 | } |
| 276 | |
| 277 | void lflags_to_rflags(CPUX86State *env) |
| 278 | { |
| 279 | env->eflags &= ~(CC_C|CC_P|CC_A|CC_Z|CC_S|CC_O); |
| 280 | /* rotate left by one to move carry-out bits into CF and AF */ |
| 281 | env->eflags |= ( |
| 282 | (env->cc_src << 1) | |
| 283 | (env->cc_src >> (TARGET_LONG_BITS - 1))) & (CC_C | CC_A); |
| 284 | env->eflags |= get_SF(env); |
| 285 | env->eflags |= get_PF(env); |
| 286 | env->eflags |= get_ZF(env); |
| 287 | env->eflags |= get_OF(env); |
| 288 | } |
| 289 | |
| 290 | void rflags_to_lflags(CPUX86State *env) |
| 291 | { |
| 292 | target_ulong cf_af, cf_xor_of; |
| 293 | |
| 294 | /* compute DST and SRC2 that reconstruct ZF/SF/PF. */ |
| 295 | env->cc_dst = ~env->eflags & CC_Z; /* DST = 0 if ZF=1 */ |
| 296 | env->cc_src2 = ~env->eflags & CC_P; /* odd parity if PF=0 */ |
| 297 | env->cc_src2 ^= -!!(env->eflags & CC_S); |
| 298 | |
| 299 | /* rotate right by one to move CF and AF into the carry-out positions */ |
| 300 | cf_af = env->eflags & (CC_C | CC_A); |
| 301 | env->cc_src = ((cf_af >> 1) | (cf_af << (TARGET_LONG_BITS - 1))); |
| 302 | |
| 303 | cf_xor_of = ((env->eflags & (CC_C | CC_O)) + (CC_O - CC_C)) & CC_O; |
| 304 | env->cc_src |= -cf_xor_of & LF_MASK_PO; |
| 305 | } |