1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 1996, 97, 2000, 2001 by Ralf Baechle 7 * Copyright (C) 2001 MIPS Technologies, Inc. 8 */ 9 #include <linux/kernel.h> 10 #include <linux/sched.h> 11 #include <linux/signal.h> 12 #include <linux/module.h> 13 #include <asm/branch.h> 14 #include <asm/cpu.h> 15 #include <asm/cpu-features.h> 16 #include <asm/fpu.h> 17 #include <asm/fpu_emulator.h> 18 #include <asm/inst.h> 19 #include <asm/ptrace.h> 20 #include <asm/uaccess.h> 21 22 /* 23 * Calculate and return exception PC in case of branch delay slot 24 * for microMIPS and MIPS16e. It does not clear the ISA mode bit. 25 */ 26 int __isa_exception_epc(struct pt_regs *regs) 27 { 28 unsigned short inst; 29 long epc = regs->cp0_epc; 30 31 /* Calculate exception PC in branch delay slot. */ 32 if (__get_user(inst, (u16 __user *) msk_isa16_mode(epc))) { 33 /* This should never happen because delay slot was checked. */ 34 force_sig(SIGSEGV, current); 35 return epc; 36 } 37 if (cpu_has_mips16) { 38 if (((union mips16e_instruction)inst).ri.opcode 39 == MIPS16e_jal_op) 40 epc += 4; 41 else 42 epc += 2; 43 } else if (mm_insn_16bit(inst)) 44 epc += 2; 45 else 46 epc += 4; 47 48 return epc; 49 } 50 51 /* (microMIPS) Convert 16-bit register encoding to 32-bit register encoding. */ 52 static const unsigned int reg16to32map[8] = {16, 17, 2, 3, 4, 5, 6, 7}; 53 54 int __mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn, 55 unsigned long *contpc) 56 { 57 union mips_instruction insn = (union mips_instruction)dec_insn.insn; 58 int bc_false = 0; 59 unsigned int fcr31; 60 unsigned int bit; 61 62 if (!cpu_has_mmips) 63 return 0; 64 65 switch (insn.mm_i_format.opcode) { 66 case mm_pool32a_op: 67 if ((insn.mm_i_format.simmediate & MM_POOL32A_MINOR_MASK) == 68 mm_pool32axf_op) { 69 switch (insn.mm_i_format.simmediate >> 70 MM_POOL32A_MINOR_SHIFT) { 71 case mm_jalr_op: 72 case mm_jalrhb_op: 73 case mm_jalrs_op: 74 case mm_jalrshb_op: 75 if (insn.mm_i_format.rt != 0) /* Not mm_jr */ 76 regs->regs[insn.mm_i_format.rt] = 77 regs->cp0_epc + 78 dec_insn.pc_inc + 79 dec_insn.next_pc_inc; 80 *contpc = regs->regs[insn.mm_i_format.rs]; 81 return 1; 82 } 83 } 84 break; 85 case mm_pool32i_op: 86 switch (insn.mm_i_format.rt) { 87 case mm_bltzals_op: 88 case mm_bltzal_op: 89 regs->regs[31] = regs->cp0_epc + 90 dec_insn.pc_inc + 91 dec_insn.next_pc_inc; 92 /* Fall through */ 93 case mm_bltz_op: 94 if ((long)regs->regs[insn.mm_i_format.rs] < 0) 95 *contpc = regs->cp0_epc + 96 dec_insn.pc_inc + 97 (insn.mm_i_format.simmediate << 1); 98 else 99 *contpc = regs->cp0_epc + 100 dec_insn.pc_inc + 101 dec_insn.next_pc_inc; 102 return 1; 103 case mm_bgezals_op: 104 case mm_bgezal_op: 105 regs->regs[31] = regs->cp0_epc + 106 dec_insn.pc_inc + 107 dec_insn.next_pc_inc; 108 /* Fall through */ 109 case mm_bgez_op: 110 if ((long)regs->regs[insn.mm_i_format.rs] >= 0) 111 *contpc = regs->cp0_epc + 112 dec_insn.pc_inc + 113 (insn.mm_i_format.simmediate << 1); 114 else 115 *contpc = regs->cp0_epc + 116 dec_insn.pc_inc + 117 dec_insn.next_pc_inc; 118 return 1; 119 case mm_blez_op: 120 if ((long)regs->regs[insn.mm_i_format.rs] <= 0) 121 *contpc = regs->cp0_epc + 122 dec_insn.pc_inc + 123 (insn.mm_i_format.simmediate << 1); 124 else 125 *contpc = regs->cp0_epc + 126 dec_insn.pc_inc + 127 dec_insn.next_pc_inc; 128 return 1; 129 case mm_bgtz_op: 130 if ((long)regs->regs[insn.mm_i_format.rs] <= 0) 131 *contpc = regs->cp0_epc + 132 dec_insn.pc_inc + 133 (insn.mm_i_format.simmediate << 1); 134 else 135 *contpc = regs->cp0_epc + 136 dec_insn.pc_inc + 137 dec_insn.next_pc_inc; 138 return 1; 139 case mm_bc2f_op: 140 case mm_bc1f_op: 141 bc_false = 1; 142 /* Fall through */ 143 case mm_bc2t_op: 144 case mm_bc1t_op: 145 preempt_disable(); 146 if (is_fpu_owner()) 147 fcr31 = read_32bit_cp1_register(CP1_STATUS); 148 else 149 fcr31 = current->thread.fpu.fcr31; 150 preempt_enable(); 151 152 if (bc_false) 153 fcr31 = ~fcr31; 154 155 bit = (insn.mm_i_format.rs >> 2); 156 bit += (bit != 0); 157 bit += 23; 158 if (fcr31 & (1 << bit)) 159 *contpc = regs->cp0_epc + 160 dec_insn.pc_inc + 161 (insn.mm_i_format.simmediate << 1); 162 else 163 *contpc = regs->cp0_epc + 164 dec_insn.pc_inc + dec_insn.next_pc_inc; 165 return 1; 166 } 167 break; 168 case mm_pool16c_op: 169 switch (insn.mm_i_format.rt) { 170 case mm_jalr16_op: 171 case mm_jalrs16_op: 172 regs->regs[31] = regs->cp0_epc + 173 dec_insn.pc_inc + dec_insn.next_pc_inc; 174 /* Fall through */ 175 case mm_jr16_op: 176 *contpc = regs->regs[insn.mm_i_format.rs]; 177 return 1; 178 } 179 break; 180 case mm_beqz16_op: 181 if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] == 0) 182 *contpc = regs->cp0_epc + 183 dec_insn.pc_inc + 184 (insn.mm_b1_format.simmediate << 1); 185 else 186 *contpc = regs->cp0_epc + 187 dec_insn.pc_inc + dec_insn.next_pc_inc; 188 return 1; 189 case mm_bnez16_op: 190 if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] != 0) 191 *contpc = regs->cp0_epc + 192 dec_insn.pc_inc + 193 (insn.mm_b1_format.simmediate << 1); 194 else 195 *contpc = regs->cp0_epc + 196 dec_insn.pc_inc + dec_insn.next_pc_inc; 197 return 1; 198 case mm_b16_op: 199 *contpc = regs->cp0_epc + dec_insn.pc_inc + 200 (insn.mm_b0_format.simmediate << 1); 201 return 1; 202 case mm_beq32_op: 203 if (regs->regs[insn.mm_i_format.rs] == 204 regs->regs[insn.mm_i_format.rt]) 205 *contpc = regs->cp0_epc + 206 dec_insn.pc_inc + 207 (insn.mm_i_format.simmediate << 1); 208 else 209 *contpc = regs->cp0_epc + 210 dec_insn.pc_inc + 211 dec_insn.next_pc_inc; 212 return 1; 213 case mm_bne32_op: 214 if (regs->regs[insn.mm_i_format.rs] != 215 regs->regs[insn.mm_i_format.rt]) 216 *contpc = regs->cp0_epc + 217 dec_insn.pc_inc + 218 (insn.mm_i_format.simmediate << 1); 219 else 220 *contpc = regs->cp0_epc + 221 dec_insn.pc_inc + dec_insn.next_pc_inc; 222 return 1; 223 case mm_jalx32_op: 224 regs->regs[31] = regs->cp0_epc + 225 dec_insn.pc_inc + dec_insn.next_pc_inc; 226 *contpc = regs->cp0_epc + dec_insn.pc_inc; 227 *contpc >>= 28; 228 *contpc <<= 28; 229 *contpc |= (insn.j_format.target << 2); 230 return 1; 231 case mm_jals32_op: 232 case mm_jal32_op: 233 regs->regs[31] = regs->cp0_epc + 234 dec_insn.pc_inc + dec_insn.next_pc_inc; 235 /* Fall through */ 236 case mm_j32_op: 237 *contpc = regs->cp0_epc + dec_insn.pc_inc; 238 *contpc >>= 27; 239 *contpc <<= 27; 240 *contpc |= (insn.j_format.target << 1); 241 set_isa16_mode(*contpc); 242 return 1; 243 } 244 return 0; 245 } 246 247 /* 248 * Compute return address and emulate branch in microMIPS mode after an 249 * exception only. It does not handle compact branches/jumps and cannot 250 * be used in interrupt context. (Compact branches/jumps do not cause 251 * exceptions.) 252 */ 253 int __microMIPS_compute_return_epc(struct pt_regs *regs) 254 { 255 u16 __user *pc16; 256 u16 halfword; 257 unsigned int word; 258 unsigned long contpc; 259 struct mm_decoded_insn mminsn = { 0 }; 260 261 mminsn.micro_mips_mode = 1; 262 263 /* This load never faults. */ 264 pc16 = (unsigned short __user *)msk_isa16_mode(regs->cp0_epc); 265 __get_user(halfword, pc16); 266 pc16++; 267 contpc = regs->cp0_epc + 2; 268 word = ((unsigned int)halfword << 16); 269 mminsn.pc_inc = 2; 270 271 if (!mm_insn_16bit(halfword)) { 272 __get_user(halfword, pc16); 273 pc16++; 274 contpc = regs->cp0_epc + 4; 275 mminsn.pc_inc = 4; 276 word |= halfword; 277 } 278 mminsn.insn = word; 279 280 if (get_user(halfword, pc16)) 281 goto sigsegv; 282 mminsn.next_pc_inc = 2; 283 word = ((unsigned int)halfword << 16); 284 285 if (!mm_insn_16bit(halfword)) { 286 pc16++; 287 if (get_user(halfword, pc16)) 288 goto sigsegv; 289 mminsn.next_pc_inc = 4; 290 word |= halfword; 291 } 292 mminsn.next_insn = word; 293 294 mm_isBranchInstr(regs, mminsn, &contpc); 295 296 regs->cp0_epc = contpc; 297 298 return 0; 299 300 sigsegv: 301 force_sig(SIGSEGV, current); 302 return -EFAULT; 303 } 304 305 /* 306 * Compute return address and emulate branch in MIPS16e mode after an 307 * exception only. It does not handle compact branches/jumps and cannot 308 * be used in interrupt context. (Compact branches/jumps do not cause 309 * exceptions.) 310 */ 311 int __MIPS16e_compute_return_epc(struct pt_regs *regs) 312 { 313 u16 __user *addr; 314 union mips16e_instruction inst; 315 u16 inst2; 316 u32 fullinst; 317 long epc; 318 319 epc = regs->cp0_epc; 320 321 /* Read the instruction. */ 322 addr = (u16 __user *)msk_isa16_mode(epc); 323 if (__get_user(inst.full, addr)) { 324 force_sig(SIGSEGV, current); 325 return -EFAULT; 326 } 327 328 switch (inst.ri.opcode) { 329 case MIPS16e_extend_op: 330 regs->cp0_epc += 4; 331 return 0; 332 333 /* 334 * JAL and JALX in MIPS16e mode 335 */ 336 case MIPS16e_jal_op: 337 addr += 1; 338 if (__get_user(inst2, addr)) { 339 force_sig(SIGSEGV, current); 340 return -EFAULT; 341 } 342 fullinst = ((unsigned)inst.full << 16) | inst2; 343 regs->regs[31] = epc + 6; 344 epc += 4; 345 epc >>= 28; 346 epc <<= 28; 347 /* 348 * JAL:5 X:1 TARGET[20-16]:5 TARGET[25:21]:5 TARGET[15:0]:16 349 * 350 * ......TARGET[15:0].................TARGET[20:16]........... 351 * ......TARGET[25:21] 352 */ 353 epc |= 354 ((fullinst & 0xffff) << 2) | ((fullinst & 0x3e00000) >> 3) | 355 ((fullinst & 0x1f0000) << 7); 356 if (!inst.jal.x) 357 set_isa16_mode(epc); /* Set ISA mode bit. */ 358 regs->cp0_epc = epc; 359 return 0; 360 361 /* 362 * J(AL)R(C) 363 */ 364 case MIPS16e_rr_op: 365 if (inst.rr.func == MIPS16e_jr_func) { 366 367 if (inst.rr.ra) 368 regs->cp0_epc = regs->regs[31]; 369 else 370 regs->cp0_epc = 371 regs->regs[reg16to32[inst.rr.rx]]; 372 373 if (inst.rr.l) { 374 if (inst.rr.nd) 375 regs->regs[31] = epc + 2; 376 else 377 regs->regs[31] = epc + 4; 378 } 379 return 0; 380 } 381 break; 382 } 383 384 /* 385 * All other cases have no branch delay slot and are 16-bits. 386 * Branches do not cause an exception. 387 */ 388 regs->cp0_epc += 2; 389 390 return 0; 391 } 392 393 /** 394 * __compute_return_epc_for_insn - Computes the return address and do emulate 395 * branch simulation, if required. 396 * 397 * @regs: Pointer to pt_regs 398 * @insn: branch instruction to decode 399 * @returns: -EFAULT on error and forces SIGBUS, and on success 400 * returns 0 or BRANCH_LIKELY_TAKEN as appropriate after 401 * evaluating the branch. 402 */ 403 int __compute_return_epc_for_insn(struct pt_regs *regs, 404 union mips_instruction insn) 405 { 406 unsigned int bit, fcr31, dspcontrol; 407 long epc = regs->cp0_epc; 408 int ret = 0; 409 410 switch (insn.i_format.opcode) { 411 /* 412 * jr and jalr are in r_format format. 413 */ 414 case spec_op: 415 switch (insn.r_format.func) { 416 case jalr_op: 417 regs->regs[insn.r_format.rd] = epc + 8; 418 /* Fall through */ 419 case jr_op: 420 regs->cp0_epc = regs->regs[insn.r_format.rs]; 421 break; 422 } 423 break; 424 425 /* 426 * This group contains: 427 * bltz_op, bgez_op, bltzl_op, bgezl_op, 428 * bltzal_op, bgezal_op, bltzall_op, bgezall_op. 429 */ 430 case bcond_op: 431 switch (insn.i_format.rt) { 432 case bltz_op: 433 case bltzl_op: 434 if ((long)regs->regs[insn.i_format.rs] < 0) { 435 epc = epc + 4 + (insn.i_format.simmediate << 2); 436 if (insn.i_format.rt == bltzl_op) 437 ret = BRANCH_LIKELY_TAKEN; 438 } else 439 epc += 8; 440 regs->cp0_epc = epc; 441 break; 442 443 case bgez_op: 444 case bgezl_op: 445 if ((long)regs->regs[insn.i_format.rs] >= 0) { 446 epc = epc + 4 + (insn.i_format.simmediate << 2); 447 if (insn.i_format.rt == bgezl_op) 448 ret = BRANCH_LIKELY_TAKEN; 449 } else 450 epc += 8; 451 regs->cp0_epc = epc; 452 break; 453 454 case bltzal_op: 455 case bltzall_op: 456 regs->regs[31] = epc + 8; 457 if ((long)regs->regs[insn.i_format.rs] < 0) { 458 epc = epc + 4 + (insn.i_format.simmediate << 2); 459 if (insn.i_format.rt == bltzall_op) 460 ret = BRANCH_LIKELY_TAKEN; 461 } else 462 epc += 8; 463 regs->cp0_epc = epc; 464 break; 465 466 case bgezal_op: 467 case bgezall_op: 468 regs->regs[31] = epc + 8; 469 if ((long)regs->regs[insn.i_format.rs] >= 0) { 470 epc = epc + 4 + (insn.i_format.simmediate << 2); 471 if (insn.i_format.rt == bgezall_op) 472 ret = BRANCH_LIKELY_TAKEN; 473 } else 474 epc += 8; 475 regs->cp0_epc = epc; 476 break; 477 478 case bposge32_op: 479 if (!cpu_has_dsp) 480 goto sigill; 481 482 dspcontrol = rddsp(0x01); 483 484 if (dspcontrol >= 32) { 485 epc = epc + 4 + (insn.i_format.simmediate << 2); 486 } else 487 epc += 8; 488 regs->cp0_epc = epc; 489 break; 490 } 491 break; 492 493 /* 494 * These are unconditional and in j_format. 495 */ 496 case jal_op: 497 regs->regs[31] = regs->cp0_epc + 8; 498 case j_op: 499 epc += 4; 500 epc >>= 28; 501 epc <<= 28; 502 epc |= (insn.j_format.target << 2); 503 regs->cp0_epc = epc; 504 if (insn.i_format.opcode == jalx_op) 505 set_isa16_mode(regs->cp0_epc); 506 break; 507 508 /* 509 * These are conditional and in i_format. 510 */ 511 case beq_op: 512 case beql_op: 513 if (regs->regs[insn.i_format.rs] == 514 regs->regs[insn.i_format.rt]) { 515 epc = epc + 4 + (insn.i_format.simmediate << 2); 516 if (insn.i_format.opcode == beql_op) 517 ret = BRANCH_LIKELY_TAKEN; 518 } else 519 epc += 8; 520 regs->cp0_epc = epc; 521 break; 522 523 case bne_op: 524 case bnel_op: 525 if (regs->regs[insn.i_format.rs] != 526 regs->regs[insn.i_format.rt]) { 527 epc = epc + 4 + (insn.i_format.simmediate << 2); 528 if (insn.i_format.opcode == bnel_op) 529 ret = BRANCH_LIKELY_TAKEN; 530 } else 531 epc += 8; 532 regs->cp0_epc = epc; 533 break; 534 535 case blez_op: /* not really i_format */ 536 case blezl_op: 537 /* rt field assumed to be zero */ 538 if ((long)regs->regs[insn.i_format.rs] <= 0) { 539 epc = epc + 4 + (insn.i_format.simmediate << 2); 540 if (insn.i_format.opcode == blezl_op) 541 ret = BRANCH_LIKELY_TAKEN; 542 } else 543 epc += 8; 544 regs->cp0_epc = epc; 545 break; 546 547 case bgtz_op: 548 case bgtzl_op: 549 /* rt field assumed to be zero */ 550 if ((long)regs->regs[insn.i_format.rs] > 0) { 551 epc = epc + 4 + (insn.i_format.simmediate << 2); 552 if (insn.i_format.opcode == bgtzl_op) 553 ret = BRANCH_LIKELY_TAKEN; 554 } else 555 epc += 8; 556 regs->cp0_epc = epc; 557 break; 558 559 /* 560 * And now the FPA/cp1 branch instructions. 561 */ 562 case cop1_op: 563 preempt_disable(); 564 if (is_fpu_owner()) 565 fcr31 = read_32bit_cp1_register(CP1_STATUS); 566 else 567 fcr31 = current->thread.fpu.fcr31; 568 preempt_enable(); 569 570 bit = (insn.i_format.rt >> 2); 571 bit += (bit != 0); 572 bit += 23; 573 switch (insn.i_format.rt & 3) { 574 case 0: /* bc1f */ 575 case 2: /* bc1fl */ 576 if (~fcr31 & (1 << bit)) { 577 epc = epc + 4 + (insn.i_format.simmediate << 2); 578 if (insn.i_format.rt == 2) 579 ret = BRANCH_LIKELY_TAKEN; 580 } else 581 epc += 8; 582 regs->cp0_epc = epc; 583 break; 584 585 case 1: /* bc1t */ 586 case 3: /* bc1tl */ 587 if (fcr31 & (1 << bit)) { 588 epc = epc + 4 + (insn.i_format.simmediate << 2); 589 if (insn.i_format.rt == 3) 590 ret = BRANCH_LIKELY_TAKEN; 591 } else 592 epc += 8; 593 regs->cp0_epc = epc; 594 break; 595 } 596 break; 597 #ifdef CONFIG_CPU_CAVIUM_OCTEON 598 case lwc2_op: /* This is bbit0 on Octeon */ 599 if ((regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt)) 600 == 0) 601 epc = epc + 4 + (insn.i_format.simmediate << 2); 602 else 603 epc += 8; 604 regs->cp0_epc = epc; 605 break; 606 case ldc2_op: /* This is bbit032 on Octeon */ 607 if ((regs->regs[insn.i_format.rs] & 608 (1ull<<(insn.i_format.rt+32))) == 0) 609 epc = epc + 4 + (insn.i_format.simmediate << 2); 610 else 611 epc += 8; 612 regs->cp0_epc = epc; 613 break; 614 case swc2_op: /* This is bbit1 on Octeon */ 615 if (regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt)) 616 epc = epc + 4 + (insn.i_format.simmediate << 2); 617 else 618 epc += 8; 619 regs->cp0_epc = epc; 620 break; 621 case sdc2_op: /* This is bbit132 on Octeon */ 622 if (regs->regs[insn.i_format.rs] & 623 (1ull<<(insn.i_format.rt+32))) 624 epc = epc + 4 + (insn.i_format.simmediate << 2); 625 else 626 epc += 8; 627 regs->cp0_epc = epc; 628 break; 629 #endif 630 } 631 632 return ret; 633 634 sigill: 635 printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm); 636 force_sig(SIGBUS, current); 637 return -EFAULT; 638 } 639 EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn); 640 641 int __compute_return_epc(struct pt_regs *regs) 642 { 643 unsigned int __user *addr; 644 long epc; 645 union mips_instruction insn; 646 647 epc = regs->cp0_epc; 648 if (epc & 3) 649 goto unaligned; 650 651 /* 652 * Read the instruction 653 */ 654 addr = (unsigned int __user *) epc; 655 if (__get_user(insn.word, addr)) { 656 force_sig(SIGSEGV, current); 657 return -EFAULT; 658 } 659 660 return __compute_return_epc_for_insn(regs, insn); 661 662 unaligned: 663 printk("%s: unaligned epc - sending SIGBUS.\n", current->comm); 664 force_sig(SIGBUS, current); 665 return -EFAULT; 666 } 667