Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Handle unaligned accesses by emulation. |
| 3 | * |
| 4 | * This file is subject to the terms and conditions of the GNU General Public |
| 5 | * License. See the file "COPYING" in the main directory of this archive |
| 6 | * for more details. |
| 7 | * |
| 8 | * Copyright (C) 1996, 1998, 1999, 2002 by Ralf Baechle |
| 9 | * Copyright (C) 1999 Silicon Graphics, Inc. |
| 10 | * |
| 11 | * This file contains exception handler for address error exception with the |
| 12 | * special capability to execute faulting instructions in software. The |
| 13 | * handler does not try to handle the case when the program counter points |
| 14 | * to an address not aligned to a word boundary. |
| 15 | * |
| 16 | * Putting data to unaligned addresses is a bad practice even on Intel where |
| 17 | * only the performance is affected. Much worse is that such code is non- |
| 18 | * portable. Due to several programs that die on MIPS due to alignment |
| 19 | * problems I decided to implement this handler anyway though I originally |
| 20 | * didn't intend to do this at all for user code. |
| 21 | * |
| 22 | * For now I enable fixing of address errors by default to make life easier. |
| 23 | * I however intend to disable this somewhen in the future when the alignment |
| 24 | * problems with user programs have been fixed. For programmers this is the |
| 25 | * right way to go. |
| 26 | * |
| 27 | * Fixing address errors is a per process option. The option is inherited |
| 28 | * across fork(2) and execve(2) calls. If you really want to use the |
| 29 | * option in your user programs - I discourage the use of the software |
| 30 | * emulation strongly - use the following code in your userland stuff: |
| 31 | * |
| 32 | * #include <sys/sysmips.h> |
| 33 | * |
| 34 | * ... |
| 35 | * sysmips(MIPS_FIXADE, x); |
| 36 | * ... |
| 37 | * |
| 38 | * The argument x is 0 for disabling software emulation, enabled otherwise. |
| 39 | * |
| 40 | * Below a little program to play around with this feature. |
| 41 | * |
| 42 | * #include <stdio.h> |
| 43 | * #include <sys/sysmips.h> |
| 44 | * |
| 45 | * struct foo { |
| 46 | * unsigned char bar[8]; |
| 47 | * }; |
| 48 | * |
| 49 | * main(int argc, char *argv[]) |
| 50 | * { |
| 51 | * struct foo x = {0, 1, 2, 3, 4, 5, 6, 7}; |
| 52 | * unsigned int *p = (unsigned int *) (x.bar + 3); |
| 53 | * int i; |
| 54 | * |
| 55 | * if (argc > 1) |
| 56 | * sysmips(MIPS_FIXADE, atoi(argv[1])); |
| 57 | * |
| 58 | * printf("*p = %08lx\n", *p); |
| 59 | * |
| 60 | * *p = 0xdeadface; |
| 61 | * |
| 62 | * for(i = 0; i <= 7; i++) |
| 63 | * printf("%02x ", x.bar[i]); |
| 64 | * printf("\n"); |
| 65 | * } |
| 66 | * |
| 67 | * Coprocessor loads are not supported; I think this case is unimportant |
| 68 | * in the practice. |
| 69 | * |
| 70 | * TODO: Handle ndc (attempted store to doubleword in uncached memory) |
| 71 | * exception for the R6000. |
| 72 | * A store crossing a page boundary might be executed only partially. |
| 73 | * Undo the partial store in this case. |
| 74 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | #include <linux/mm.h> |
| 76 | #include <linux/module.h> |
| 77 | #include <linux/signal.h> |
| 78 | #include <linux/smp.h> |
| 79 | #include <linux/smp_lock.h> |
| 80 | |
| 81 | #include <asm/asm.h> |
| 82 | #include <asm/branch.h> |
| 83 | #include <asm/byteorder.h> |
| 84 | #include <asm/inst.h> |
| 85 | #include <asm/uaccess.h> |
| 86 | #include <asm/system.h> |
| 87 | |
| 88 | #define STR(x) __STR(x) |
| 89 | #define __STR(x) #x |
| 90 | |
| 91 | #ifdef CONFIG_PROC_FS |
| 92 | unsigned long unaligned_instructions; |
| 93 | #endif |
| 94 | |
| 95 | static inline int emulate_load_store_insn(struct pt_regs *regs, |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 96 | void __user *addr, unsigned int __user *pc, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 97 | unsigned long **regptr, unsigned long *newvalue) |
| 98 | { |
| 99 | union mips_instruction insn; |
| 100 | unsigned long value; |
| 101 | unsigned int res; |
| 102 | |
| 103 | regs->regs[0] = 0; |
| 104 | *regptr=NULL; |
| 105 | |
| 106 | /* |
| 107 | * This load never faults. |
| 108 | */ |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 109 | __get_user(insn.word, pc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | |
| 111 | switch (insn.i_format.opcode) { |
| 112 | /* |
| 113 | * These are instructions that a compiler doesn't generate. We |
| 114 | * can assume therefore that the code is MIPS-aware and |
| 115 | * really buggy. Emulating these instructions would break the |
| 116 | * semantics anyway. |
| 117 | */ |
| 118 | case ll_op: |
| 119 | case lld_op: |
| 120 | case sc_op: |
| 121 | case scd_op: |
| 122 | |
| 123 | /* |
| 124 | * For these instructions the only way to create an address |
| 125 | * error is an attempted access to kernel/supervisor address |
| 126 | * space. |
| 127 | */ |
| 128 | case ldl_op: |
| 129 | case ldr_op: |
| 130 | case lwl_op: |
| 131 | case lwr_op: |
| 132 | case sdl_op: |
| 133 | case sdr_op: |
| 134 | case swl_op: |
| 135 | case swr_op: |
| 136 | case lb_op: |
| 137 | case lbu_op: |
| 138 | case sb_op: |
| 139 | goto sigbus; |
| 140 | |
| 141 | /* |
| 142 | * The remaining opcodes are the ones that are really of interest. |
| 143 | */ |
| 144 | case lh_op: |
| 145 | if (!access_ok(VERIFY_READ, addr, 2)) |
| 146 | goto sigbus; |
| 147 | |
| 148 | __asm__ __volatile__ (".set\tnoat\n" |
| 149 | #ifdef __BIG_ENDIAN |
| 150 | "1:\tlb\t%0, 0(%2)\n" |
| 151 | "2:\tlbu\t$1, 1(%2)\n\t" |
| 152 | #endif |
| 153 | #ifdef __LITTLE_ENDIAN |
| 154 | "1:\tlb\t%0, 1(%2)\n" |
| 155 | "2:\tlbu\t$1, 0(%2)\n\t" |
| 156 | #endif |
| 157 | "sll\t%0, 0x8\n\t" |
| 158 | "or\t%0, $1\n\t" |
| 159 | "li\t%1, 0\n" |
| 160 | "3:\t.set\tat\n\t" |
| 161 | ".section\t.fixup,\"ax\"\n\t" |
| 162 | "4:\tli\t%1, %3\n\t" |
| 163 | "j\t3b\n\t" |
| 164 | ".previous\n\t" |
| 165 | ".section\t__ex_table,\"a\"\n\t" |
| 166 | STR(PTR)"\t1b, 4b\n\t" |
| 167 | STR(PTR)"\t2b, 4b\n\t" |
| 168 | ".previous" |
| 169 | : "=&r" (value), "=r" (res) |
| 170 | : "r" (addr), "i" (-EFAULT)); |
| 171 | if (res) |
| 172 | goto fault; |
| 173 | *newvalue = value; |
| 174 | *regptr = ®s->regs[insn.i_format.rt]; |
| 175 | break; |
| 176 | |
| 177 | case lw_op: |
| 178 | if (!access_ok(VERIFY_READ, addr, 4)) |
| 179 | goto sigbus; |
| 180 | |
| 181 | __asm__ __volatile__ ( |
| 182 | #ifdef __BIG_ENDIAN |
| 183 | "1:\tlwl\t%0, (%2)\n" |
| 184 | "2:\tlwr\t%0, 3(%2)\n\t" |
| 185 | #endif |
| 186 | #ifdef __LITTLE_ENDIAN |
| 187 | "1:\tlwl\t%0, 3(%2)\n" |
| 188 | "2:\tlwr\t%0, (%2)\n\t" |
| 189 | #endif |
| 190 | "li\t%1, 0\n" |
| 191 | "3:\t.section\t.fixup,\"ax\"\n\t" |
| 192 | "4:\tli\t%1, %3\n\t" |
| 193 | "j\t3b\n\t" |
| 194 | ".previous\n\t" |
| 195 | ".section\t__ex_table,\"a\"\n\t" |
| 196 | STR(PTR)"\t1b, 4b\n\t" |
| 197 | STR(PTR)"\t2b, 4b\n\t" |
| 198 | ".previous" |
| 199 | : "=&r" (value), "=r" (res) |
| 200 | : "r" (addr), "i" (-EFAULT)); |
| 201 | if (res) |
| 202 | goto fault; |
| 203 | *newvalue = value; |
| 204 | *regptr = ®s->regs[insn.i_format.rt]; |
| 205 | break; |
| 206 | |
| 207 | case lhu_op: |
| 208 | if (!access_ok(VERIFY_READ, addr, 2)) |
| 209 | goto sigbus; |
| 210 | |
| 211 | __asm__ __volatile__ ( |
| 212 | ".set\tnoat\n" |
| 213 | #ifdef __BIG_ENDIAN |
| 214 | "1:\tlbu\t%0, 0(%2)\n" |
| 215 | "2:\tlbu\t$1, 1(%2)\n\t" |
| 216 | #endif |
| 217 | #ifdef __LITTLE_ENDIAN |
| 218 | "1:\tlbu\t%0, 1(%2)\n" |
| 219 | "2:\tlbu\t$1, 0(%2)\n\t" |
| 220 | #endif |
| 221 | "sll\t%0, 0x8\n\t" |
| 222 | "or\t%0, $1\n\t" |
| 223 | "li\t%1, 0\n" |
| 224 | "3:\t.set\tat\n\t" |
| 225 | ".section\t.fixup,\"ax\"\n\t" |
| 226 | "4:\tli\t%1, %3\n\t" |
| 227 | "j\t3b\n\t" |
| 228 | ".previous\n\t" |
| 229 | ".section\t__ex_table,\"a\"\n\t" |
| 230 | STR(PTR)"\t1b, 4b\n\t" |
| 231 | STR(PTR)"\t2b, 4b\n\t" |
| 232 | ".previous" |
| 233 | : "=&r" (value), "=r" (res) |
| 234 | : "r" (addr), "i" (-EFAULT)); |
| 235 | if (res) |
| 236 | goto fault; |
| 237 | *newvalue = value; |
| 238 | *regptr = ®s->regs[insn.i_format.rt]; |
| 239 | break; |
| 240 | |
| 241 | case lwu_op: |
Ralf Baechle | 875d43e | 2005-09-03 15:56:16 -0700 | [diff] [blame] | 242 | #ifdef CONFIG_64BIT |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 243 | /* |
| 244 | * A 32-bit kernel might be running on a 64-bit processor. But |
| 245 | * if we're on a 32-bit processor and an i-cache incoherency |
| 246 | * or race makes us see a 64-bit instruction here the sdl/sdr |
| 247 | * would blow up, so for now we don't handle unaligned 64-bit |
| 248 | * instructions on 32-bit kernels. |
| 249 | */ |
| 250 | if (!access_ok(VERIFY_READ, addr, 4)) |
| 251 | goto sigbus; |
| 252 | |
| 253 | __asm__ __volatile__ ( |
| 254 | #ifdef __BIG_ENDIAN |
| 255 | "1:\tlwl\t%0, (%2)\n" |
| 256 | "2:\tlwr\t%0, 3(%2)\n\t" |
| 257 | #endif |
| 258 | #ifdef __LITTLE_ENDIAN |
| 259 | "1:\tlwl\t%0, 3(%2)\n" |
| 260 | "2:\tlwr\t%0, (%2)\n\t" |
| 261 | #endif |
| 262 | "dsll\t%0, %0, 32\n\t" |
| 263 | "dsrl\t%0, %0, 32\n\t" |
| 264 | "li\t%1, 0\n" |
| 265 | "3:\t.section\t.fixup,\"ax\"\n\t" |
| 266 | "4:\tli\t%1, %3\n\t" |
| 267 | "j\t3b\n\t" |
| 268 | ".previous\n\t" |
| 269 | ".section\t__ex_table,\"a\"\n\t" |
| 270 | STR(PTR)"\t1b, 4b\n\t" |
| 271 | STR(PTR)"\t2b, 4b\n\t" |
| 272 | ".previous" |
| 273 | : "=&r" (value), "=r" (res) |
| 274 | : "r" (addr), "i" (-EFAULT)); |
| 275 | if (res) |
| 276 | goto fault; |
| 277 | *newvalue = value; |
| 278 | *regptr = ®s->regs[insn.i_format.rt]; |
| 279 | break; |
Ralf Baechle | 875d43e | 2005-09-03 15:56:16 -0700 | [diff] [blame] | 280 | #endif /* CONFIG_64BIT */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 281 | |
| 282 | /* Cannot handle 64-bit instructions in 32-bit kernel */ |
| 283 | goto sigill; |
| 284 | |
| 285 | case ld_op: |
Ralf Baechle | 875d43e | 2005-09-03 15:56:16 -0700 | [diff] [blame] | 286 | #ifdef CONFIG_64BIT |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 287 | /* |
| 288 | * A 32-bit kernel might be running on a 64-bit processor. But |
| 289 | * if we're on a 32-bit processor and an i-cache incoherency |
| 290 | * or race makes us see a 64-bit instruction here the sdl/sdr |
| 291 | * would blow up, so for now we don't handle unaligned 64-bit |
| 292 | * instructions on 32-bit kernels. |
| 293 | */ |
| 294 | if (!access_ok(VERIFY_READ, addr, 8)) |
| 295 | goto sigbus; |
| 296 | |
| 297 | __asm__ __volatile__ ( |
| 298 | #ifdef __BIG_ENDIAN |
| 299 | "1:\tldl\t%0, (%2)\n" |
| 300 | "2:\tldr\t%0, 7(%2)\n\t" |
| 301 | #endif |
| 302 | #ifdef __LITTLE_ENDIAN |
| 303 | "1:\tldl\t%0, 7(%2)\n" |
| 304 | "2:\tldr\t%0, (%2)\n\t" |
| 305 | #endif |
| 306 | "li\t%1, 0\n" |
| 307 | "3:\t.section\t.fixup,\"ax\"\n\t" |
| 308 | "4:\tli\t%1, %3\n\t" |
| 309 | "j\t3b\n\t" |
| 310 | ".previous\n\t" |
| 311 | ".section\t__ex_table,\"a\"\n\t" |
| 312 | STR(PTR)"\t1b, 4b\n\t" |
| 313 | STR(PTR)"\t2b, 4b\n\t" |
| 314 | ".previous" |
| 315 | : "=&r" (value), "=r" (res) |
| 316 | : "r" (addr), "i" (-EFAULT)); |
| 317 | if (res) |
| 318 | goto fault; |
| 319 | *newvalue = value; |
| 320 | *regptr = ®s->regs[insn.i_format.rt]; |
| 321 | break; |
Ralf Baechle | 875d43e | 2005-09-03 15:56:16 -0700 | [diff] [blame] | 322 | #endif /* CONFIG_64BIT */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 323 | |
| 324 | /* Cannot handle 64-bit instructions in 32-bit kernel */ |
| 325 | goto sigill; |
| 326 | |
| 327 | case sh_op: |
| 328 | if (!access_ok(VERIFY_WRITE, addr, 2)) |
| 329 | goto sigbus; |
| 330 | |
| 331 | value = regs->regs[insn.i_format.rt]; |
| 332 | __asm__ __volatile__ ( |
| 333 | #ifdef __BIG_ENDIAN |
| 334 | ".set\tnoat\n" |
| 335 | "1:\tsb\t%1, 1(%2)\n\t" |
| 336 | "srl\t$1, %1, 0x8\n" |
| 337 | "2:\tsb\t$1, 0(%2)\n\t" |
| 338 | ".set\tat\n\t" |
| 339 | #endif |
| 340 | #ifdef __LITTLE_ENDIAN |
| 341 | ".set\tnoat\n" |
| 342 | "1:\tsb\t%1, 0(%2)\n\t" |
| 343 | "srl\t$1,%1, 0x8\n" |
| 344 | "2:\tsb\t$1, 1(%2)\n\t" |
| 345 | ".set\tat\n\t" |
| 346 | #endif |
| 347 | "li\t%0, 0\n" |
| 348 | "3:\n\t" |
| 349 | ".section\t.fixup,\"ax\"\n\t" |
| 350 | "4:\tli\t%0, %3\n\t" |
| 351 | "j\t3b\n\t" |
| 352 | ".previous\n\t" |
| 353 | ".section\t__ex_table,\"a\"\n\t" |
| 354 | STR(PTR)"\t1b, 4b\n\t" |
| 355 | STR(PTR)"\t2b, 4b\n\t" |
| 356 | ".previous" |
| 357 | : "=r" (res) |
| 358 | : "r" (value), "r" (addr), "i" (-EFAULT)); |
| 359 | if (res) |
| 360 | goto fault; |
| 361 | break; |
| 362 | |
| 363 | case sw_op: |
| 364 | if (!access_ok(VERIFY_WRITE, addr, 4)) |
| 365 | goto sigbus; |
| 366 | |
| 367 | value = regs->regs[insn.i_format.rt]; |
| 368 | __asm__ __volatile__ ( |
| 369 | #ifdef __BIG_ENDIAN |
| 370 | "1:\tswl\t%1,(%2)\n" |
| 371 | "2:\tswr\t%1, 3(%2)\n\t" |
| 372 | #endif |
| 373 | #ifdef __LITTLE_ENDIAN |
| 374 | "1:\tswl\t%1, 3(%2)\n" |
| 375 | "2:\tswr\t%1, (%2)\n\t" |
| 376 | #endif |
| 377 | "li\t%0, 0\n" |
| 378 | "3:\n\t" |
| 379 | ".section\t.fixup,\"ax\"\n\t" |
| 380 | "4:\tli\t%0, %3\n\t" |
| 381 | "j\t3b\n\t" |
| 382 | ".previous\n\t" |
| 383 | ".section\t__ex_table,\"a\"\n\t" |
| 384 | STR(PTR)"\t1b, 4b\n\t" |
| 385 | STR(PTR)"\t2b, 4b\n\t" |
| 386 | ".previous" |
| 387 | : "=r" (res) |
| 388 | : "r" (value), "r" (addr), "i" (-EFAULT)); |
| 389 | if (res) |
| 390 | goto fault; |
| 391 | break; |
| 392 | |
| 393 | case sd_op: |
Ralf Baechle | 875d43e | 2005-09-03 15:56:16 -0700 | [diff] [blame] | 394 | #ifdef CONFIG_64BIT |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 395 | /* |
| 396 | * A 32-bit kernel might be running on a 64-bit processor. But |
| 397 | * if we're on a 32-bit processor and an i-cache incoherency |
| 398 | * or race makes us see a 64-bit instruction here the sdl/sdr |
| 399 | * would blow up, so for now we don't handle unaligned 64-bit |
| 400 | * instructions on 32-bit kernels. |
| 401 | */ |
| 402 | if (!access_ok(VERIFY_WRITE, addr, 8)) |
| 403 | goto sigbus; |
| 404 | |
| 405 | value = regs->regs[insn.i_format.rt]; |
| 406 | __asm__ __volatile__ ( |
| 407 | #ifdef __BIG_ENDIAN |
| 408 | "1:\tsdl\t%1,(%2)\n" |
| 409 | "2:\tsdr\t%1, 7(%2)\n\t" |
| 410 | #endif |
| 411 | #ifdef __LITTLE_ENDIAN |
| 412 | "1:\tsdl\t%1, 7(%2)\n" |
| 413 | "2:\tsdr\t%1, (%2)\n\t" |
| 414 | #endif |
| 415 | "li\t%0, 0\n" |
| 416 | "3:\n\t" |
| 417 | ".section\t.fixup,\"ax\"\n\t" |
| 418 | "4:\tli\t%0, %3\n\t" |
| 419 | "j\t3b\n\t" |
| 420 | ".previous\n\t" |
| 421 | ".section\t__ex_table,\"a\"\n\t" |
| 422 | STR(PTR)"\t1b, 4b\n\t" |
| 423 | STR(PTR)"\t2b, 4b\n\t" |
| 424 | ".previous" |
| 425 | : "=r" (res) |
| 426 | : "r" (value), "r" (addr), "i" (-EFAULT)); |
| 427 | if (res) |
| 428 | goto fault; |
| 429 | break; |
Ralf Baechle | 875d43e | 2005-09-03 15:56:16 -0700 | [diff] [blame] | 430 | #endif /* CONFIG_64BIT */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 431 | |
| 432 | /* Cannot handle 64-bit instructions in 32-bit kernel */ |
| 433 | goto sigill; |
| 434 | |
| 435 | case lwc1_op: |
| 436 | case ldc1_op: |
| 437 | case swc1_op: |
| 438 | case sdc1_op: |
| 439 | /* |
| 440 | * I herewith declare: this does not happen. So send SIGBUS. |
| 441 | */ |
| 442 | goto sigbus; |
| 443 | |
| 444 | case lwc2_op: |
| 445 | case ldc2_op: |
| 446 | case swc2_op: |
| 447 | case sdc2_op: |
| 448 | /* |
| 449 | * These are the coprocessor 2 load/stores. The current |
| 450 | * implementations don't use cp2 and cp2 should always be |
| 451 | * disabled in c0_status. So send SIGILL. |
| 452 | * (No longer true: The Sony Praystation uses cp2 for |
| 453 | * 3D matrix operations. Dunno if that thingy has a MMU ...) |
| 454 | */ |
| 455 | default: |
| 456 | /* |
| 457 | * Pheeee... We encountered an yet unknown instruction or |
| 458 | * cache coherence problem. Die sucker, die ... |
| 459 | */ |
| 460 | goto sigill; |
| 461 | } |
| 462 | |
| 463 | #ifdef CONFIG_PROC_FS |
| 464 | unaligned_instructions++; |
| 465 | #endif |
| 466 | |
| 467 | return 0; |
| 468 | |
| 469 | fault: |
| 470 | /* Did we have an exception handler installed? */ |
| 471 | if (fixup_exception(regs)) |
| 472 | return 1; |
| 473 | |
| 474 | die_if_kernel ("Unhandled kernel unaligned access", regs); |
| 475 | send_sig(SIGSEGV, current, 1); |
| 476 | |
| 477 | return 0; |
| 478 | |
| 479 | sigbus: |
| 480 | die_if_kernel("Unhandled kernel unaligned access", regs); |
| 481 | send_sig(SIGBUS, current, 1); |
| 482 | |
| 483 | return 0; |
| 484 | |
| 485 | sigill: |
| 486 | die_if_kernel("Unhandled kernel unaligned access or invalid instruction", regs); |
| 487 | send_sig(SIGILL, current, 1); |
| 488 | |
| 489 | return 0; |
| 490 | } |
| 491 | |
| 492 | asmlinkage void do_ade(struct pt_regs *regs) |
| 493 | { |
| 494 | unsigned long *regptr, newval; |
| 495 | extern int do_dsemulret(struct pt_regs *); |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 496 | unsigned int __user *pc; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 497 | mm_segment_t seg; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 498 | |
| 499 | /* |
| 500 | * Address errors may be deliberately induced by the FPU emulator to |
| 501 | * retake control of the CPU after executing the instruction in the |
| 502 | * delay slot of an emulated branch. |
| 503 | */ |
| 504 | /* Terminate if exception was recognized as a delay slot return */ |
| 505 | if (do_dsemulret(regs)) |
| 506 | return; |
| 507 | |
| 508 | /* Otherwise handle as normal */ |
| 509 | |
| 510 | /* |
| 511 | * Did we catch a fault trying to load an instruction? |
| 512 | * Or are we running in MIPS16 mode? |
| 513 | */ |
| 514 | if ((regs->cp0_badvaddr == regs->cp0_epc) || (regs->cp0_epc & 0x1)) |
| 515 | goto sigbus; |
| 516 | |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 517 | pc = (unsigned int __user *) exception_epc(regs); |
Ralf Baechle | b772e6d | 2007-02-24 21:04:04 +0000 | [diff] [blame^] | 518 | if (user_mode(regs) && (current->thread.mflags & MF_FIXADE) == 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 519 | goto sigbus; |
| 520 | |
| 521 | /* |
| 522 | * Do branch emulation only if we didn't forward the exception. |
| 523 | * This is all so but ugly ... |
| 524 | */ |
| 525 | seg = get_fs(); |
| 526 | if (!user_mode(regs)) |
| 527 | set_fs(KERNEL_DS); |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 528 | if (!emulate_load_store_insn(regs, (void __user *)regs->cp0_badvaddr, pc, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 529 | ®ptr, &newval)) { |
| 530 | compute_return_epc(regs); |
| 531 | /* |
| 532 | * Now that branch is evaluated, update the dest |
| 533 | * register if necessary |
| 534 | */ |
| 535 | if (regptr) |
| 536 | *regptr = newval; |
| 537 | } |
| 538 | set_fs(seg); |
| 539 | |
| 540 | return; |
| 541 | |
| 542 | sigbus: |
| 543 | die_if_kernel("Kernel unaligned instruction access", regs); |
| 544 | force_sig(SIGBUS, current); |
| 545 | |
| 546 | /* |
| 547 | * XXX On return from the signal handler we should advance the epc |
| 548 | */ |
| 549 | } |