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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 | // SPDX-License-Identifier: GPL-2.0 /*---------------------------------------------------------------------------+ | get_address.c | | | | Get the effective address from an FPU instruction. | | | | Copyright (C) 1992,1993,1994,1997 | | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | | Australia. E-mail billm@suburbia.net | | | | | +---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------+ | Note: | | The file contains code which accesses user memory. | | Emulator static data may change when user memory is accessed, due to | | other processes using the emulator while swapping is in progress. | +---------------------------------------------------------------------------*/ #include <linux/stddef.h> #include <linux/uaccess.h> #include <asm/vm86.h> #include "fpu_system.h" #include "exception.h" #include "fpu_emu.h" #define FPU_WRITE_BIT 0x10 static int reg_offset[] = { offsetof(struct pt_regs, ax), offsetof(struct pt_regs, cx), offsetof(struct pt_regs, dx), offsetof(struct pt_regs, bx), offsetof(struct pt_regs, sp), offsetof(struct pt_regs, bp), offsetof(struct pt_regs, si), offsetof(struct pt_regs, di) }; #define REG_(x) (*(long *)(reg_offset[(x)] + (u_char *)FPU_info->regs)) static int reg_offset_vm86[] = { offsetof(struct pt_regs, cs), offsetof(struct kernel_vm86_regs, ds), offsetof(struct kernel_vm86_regs, es), offsetof(struct kernel_vm86_regs, fs), offsetof(struct kernel_vm86_regs, gs), offsetof(struct pt_regs, ss), offsetof(struct kernel_vm86_regs, ds) }; #define VM86_REG_(x) (*(unsigned short *) \ (reg_offset_vm86[((unsigned)x)] + (u_char *)FPU_info->regs)) static int reg_offset_pm[] = { offsetof(struct pt_regs, cs), offsetof(struct pt_regs, ds), offsetof(struct pt_regs, es), offsetof(struct pt_regs, fs), offsetof(struct pt_regs, ds), /* dummy, not saved on stack */ offsetof(struct pt_regs, ss), offsetof(struct pt_regs, ds) }; #define PM_REG_(x) (*(unsigned short *) \ (reg_offset_pm[((unsigned)x)] + (u_char *)FPU_info->regs)) /* Decode the SIB byte. This function assumes mod != 0 */ static int sib(int mod, unsigned long *fpu_eip) { u_char ss, index, base; long offset; RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(1); FPU_get_user(base, (u_char __user *) (*fpu_eip)); /* The SIB byte */ RE_ENTRANT_CHECK_ON; (*fpu_eip)++; ss = base >> 6; index = (base >> 3) & 7; base &= 7; if ((mod == 0) && (base == 5)) offset = 0; /* No base register */ else offset = REG_(base); if (index == 4) { /* No index register */ /* A non-zero ss is illegal */ if (ss) EXCEPTION(EX_Invalid); } else { offset += (REG_(index)) << ss; } if (mod == 1) { /* 8 bit signed displacement */ long displacement; RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(1); FPU_get_user(displacement, (signed char __user *)(*fpu_eip)); offset += displacement; RE_ENTRANT_CHECK_ON; (*fpu_eip)++; } else if (mod == 2 || base == 5) { /* The second condition also has mod==0 */ /* 32 bit displacement */ long displacement; RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(4); FPU_get_user(displacement, (long __user *)(*fpu_eip)); offset += displacement; RE_ENTRANT_CHECK_ON; (*fpu_eip) += 4; } return offset; } static unsigned long vm86_segment(u_char segment, struct address *addr) { segment--; #ifdef PARANOID if (segment > PREFIX_SS_) { EXCEPTION(EX_INTERNAL | 0x130); math_abort(FPU_info, SIGSEGV); } #endif /* PARANOID */ addr->selector = VM86_REG_(segment); return (unsigned long)VM86_REG_(segment) << 4; } /* This should work for 16 and 32 bit protected mode. */ static long pm_address(u_char FPU_modrm, u_char segment, struct address *addr, long offset) { struct desc_struct descriptor; unsigned long base_address, limit, address, seg_top; segment--; #ifdef PARANOID /* segment is unsigned, so this also detects if segment was 0: */ if (segment > PREFIX_SS_) { EXCEPTION(EX_INTERNAL | 0x132); math_abort(FPU_info, SIGSEGV); } #endif /* PARANOID */ switch (segment) { case PREFIX_GS_ - 1: /* user gs handling can be lazy, use special accessors */ savesegment(gs, addr->selector); break; default: addr->selector = PM_REG_(segment); } descriptor = FPU_get_ldt_descriptor(addr->selector); base_address = seg_get_base(&descriptor); address = base_address + offset; limit = seg_get_limit(&descriptor) + 1; limit *= seg_get_granularity(&descriptor); limit += base_address - 1; if (limit < base_address) limit = 0xffffffff; if (seg_expands_down(&descriptor)) { if (descriptor.g) { seg_top = 0xffffffff; } else { seg_top = base_address + (1 << 20); if (seg_top < base_address) seg_top = 0xffffffff; } access_limit = (address <= limit) || (address >= seg_top) ? 0 : ((seg_top - address) >= 255 ? 255 : seg_top - address); } else { access_limit = (address > limit) || (address < base_address) ? 0 : ((limit - address) >= 254 ? 255 : limit - address + 1); } if (seg_execute_only(&descriptor) || (!seg_writable(&descriptor) && (FPU_modrm & FPU_WRITE_BIT))) { access_limit = 0; } return address; } /* MOD R/M byte: MOD == 3 has a special use for the FPU SIB byte used iff R/M = 100b 7 6 5 4 3 2 1 0 ..... ......... ......... MOD OPCODE(2) R/M SIB byte 7 6 5 4 3 2 1 0 ..... ......... ......... SS INDEX BASE */ void __user *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip, struct address *addr, fpu_addr_modes addr_modes) { u_char mod; unsigned rm = FPU_modrm & 7; long *cpu_reg_ptr; int address = 0; /* Initialized just to stop compiler warnings. */ /* Memory accessed via the cs selector is write protected in `non-segmented' 32 bit protected mode. */ if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) && (addr_modes.override.segment == PREFIX_CS_)) { math_abort(FPU_info, SIGSEGV); } addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ mod = (FPU_modrm >> 6) & 3; if (rm == 4 && mod != 3) { address = sib(mod, fpu_eip); } else { cpu_reg_ptr = ®_(rm); switch (mod) { case 0: if (rm == 5) { /* Special case: disp32 */ RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(4); FPU_get_user(address, (unsigned long __user *)(*fpu_eip)); (*fpu_eip) += 4; RE_ENTRANT_CHECK_ON; addr->offset = address; return (void __user *)address; } else { address = *cpu_reg_ptr; /* Just return the contents of the cpu register */ addr->offset = address; return (void __user *)address; } case 1: /* 8 bit signed displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(1); FPU_get_user(address, (signed char __user *)(*fpu_eip)); RE_ENTRANT_CHECK_ON; (*fpu_eip)++; break; case 2: /* 32 bit displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(4); FPU_get_user(address, (long __user *)(*fpu_eip)); (*fpu_eip) += 4; RE_ENTRANT_CHECK_ON; break; case 3: /* Not legal for the FPU */ EXCEPTION(EX_Invalid); } address += *cpu_reg_ptr; } addr->offset = address; switch (addr_modes.default_mode) { case 0: break; case VM86: address += vm86_segment(addr_modes.override.segment, addr); break; case PM16: case SEG32: address = pm_address(FPU_modrm, addr_modes.override.segment, addr, address); break; default: EXCEPTION(EX_INTERNAL | 0x133); } return (void __user *)address; } void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip, struct address *addr, fpu_addr_modes addr_modes) { u_char mod; unsigned rm = FPU_modrm & 7; int address = 0; /* Default used for mod == 0 */ /* Memory accessed via the cs selector is write protected in `non-segmented' 32 bit protected mode. */ if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) && (addr_modes.override.segment == PREFIX_CS_)) { math_abort(FPU_info, SIGSEGV); } addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ mod = (FPU_modrm >> 6) & 3; switch (mod) { case 0: if (rm == 6) { /* Special case: disp16 */ RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(2); FPU_get_user(address, (unsigned short __user *)(*fpu_eip)); (*fpu_eip) += 2; RE_ENTRANT_CHECK_ON; goto add_segment; } break; case 1: /* 8 bit signed displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(1); FPU_get_user(address, (signed char __user *)(*fpu_eip)); RE_ENTRANT_CHECK_ON; (*fpu_eip)++; break; case 2: /* 16 bit displacement */ RE_ENTRANT_CHECK_OFF; FPU_code_access_ok(2); FPU_get_user(address, (unsigned short __user *)(*fpu_eip)); (*fpu_eip) += 2; RE_ENTRANT_CHECK_ON; break; case 3: /* Not legal for the FPU */ EXCEPTION(EX_Invalid); break; } switch (rm) { case 0: address += FPU_info->regs->bx + FPU_info->regs->si; break; case 1: address += FPU_info->regs->bx + FPU_info->regs->di; break; case 2: address += FPU_info->regs->bp + FPU_info->regs->si; if (addr_modes.override.segment == PREFIX_DEFAULT) addr_modes.override.segment = PREFIX_SS_; break; case 3: address += FPU_info->regs->bp + FPU_info->regs->di; if (addr_modes.override.segment == PREFIX_DEFAULT) addr_modes.override.segment = PREFIX_SS_; break; case 4: address += FPU_info->regs->si; break; case 5: address += FPU_info->regs->di; break; case 6: address += FPU_info->regs->bp; if (addr_modes.override.segment == PREFIX_DEFAULT) addr_modes.override.segment = PREFIX_SS_; break; case 7: address += FPU_info->regs->bx; break; } add_segment: address &= 0xffff; addr->offset = address; switch (addr_modes.default_mode) { case 0: break; case VM86: address += vm86_segment(addr_modes.override.segment, addr); break; case PM16: case SEG32: address = pm_address(FPU_modrm, addr_modes.override.segment, addr, address); break; default: EXCEPTION(EX_INTERNAL | 0x131); } return (void __user *)address; } |