arch/sh/kernel/traps_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * 'traps.c' handles hardware traps and faults after we have saved some
   4  * state in 'entry.S'.
   5  *
   6  *  SuperH version: Copyright (C) 1999 Niibe Yutaka
   7  *                  Copyright (C) 2000 Philipp Rumpf
   8  *                  Copyright (C) 2000 David Howells
   9  *                  Copyright (C) 2002 - 2010 Paul Mundt
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/hardirq.h>
  14 #include <linux/init.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/kallsyms.h>
  17 #include <linux/io.h>
  18 #include <linux/bug.h>
  19 #include <linux/debug_locks.h>
  20 #include <linux/kdebug.h>
  21 #include <linux/limits.h>
  22 #include <linux/sysfs.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/perf_event.h>
  25 #include <linux/sched/task_stack.h>
  26
  27 #include <asm/alignment.h>
  28 #include <asm/fpu.h>
  29 #include <asm/kprobes.h>
  30 #include <asm/traps.h>
  31 #include <asm/bl_bit.h>
  32
  33 #ifdef CONFIG_CPU_SH2
  34 # define TRAP_RESERVED_INST     4
  35 # define TRAP_ILLEGAL_SLOT_INST 6
  36 # define TRAP_ADDRESS_ERROR     9
  37 # ifdef CONFIG_CPU_SH2A
  38 #  define TRAP_UBC              12
  39 #  define TRAP_FPU_ERROR        13
  40 #  define TRAP_DIVZERO_ERROR    17
  41 #  define TRAP_DIVOVF_ERROR     18
  42 # endif
  43 #else
  44 #define TRAP_RESERVED_INST      12
  45 #define TRAP_ILLEGAL_SLOT_INST  13
  46 #endif
  47
  48 static inline void sign_extend(unsigned int count, unsigned char *dst)
  49 {
  50 #ifdef __LITTLE_ENDIAN__
  51         if ((count == 1) && dst[0] & 0x80) {
  52                 dst[1] = 0xff;
  53                 dst[2] = 0xff;
  54                 dst[3] = 0xff;
  55         }
  56         if ((count == 2) && dst[1] & 0x80) {
  57                 dst[2] = 0xff;
  58                 dst[3] = 0xff;
  59         }
  60 #else
  61         if ((count == 1) && dst[3] & 0x80) {
  62                 dst[2] = 0xff;
  63                 dst[1] = 0xff;
  64                 dst[0] = 0xff;
  65         }
  66         if ((count == 2) && dst[2] & 0x80) {
  67                 dst[1] = 0xff;
  68                 dst[0] = 0xff;
  69         }
  70 #endif
  71 }
  72
  73 static struct mem_access user_mem_access = {
  74         copy_from_user,
  75         copy_to_user,
  76 };
  77
  78 /*
  79  * handle an instruction that does an unaligned memory access by emulating the
  80  * desired behaviour
  81  * - note that PC _may not_ point to the faulting instruction
  82  *   (if that instruction is in a branch delay slot)
  83  * - return 0 if emulation okay, -EFAULT on existential error
  84  */
  85 static int handle_unaligned_ins(insn_size_t instruction, struct pt_regs *regs,
  86                                 struct mem_access *ma)
  87 {
  88         int ret, index, count;
  89         unsigned long *rm, *rn;
  90         unsigned char *src, *dst;
  91         unsigned char __user *srcu, *dstu;
  92
  93         index = (instruction>>8)&15;    /* 0x0F00 */
  94         rn = &regs->regs[index];
  95
  96         index = (instruction>>4)&15;    /* 0x00F0 */
  97         rm = &regs->regs[index];
  98
  99         count = 1<<(instruction&3);
 100
 101         switch (count) {
 102         case 1: inc_unaligned_byte_access(); break;
 103         case 2: inc_unaligned_word_access(); break;
 104         case 4: inc_unaligned_dword_access(); break;
 105         case 8: inc_unaligned_multi_access(); break;
 106         }
 107
 108         ret = -EFAULT;
 109         switch (instruction>>12) {
 110         case 0: /* mov.[bwl] to/from memory via r0+rn */
 111                 if (instruction & 8) {
 112                         /* from memory */
 113                         srcu = (unsigned char __user *)*rm;
 114                         srcu += regs->regs[0];
 115                         dst = (unsigned char *)rn;
 116                         *(unsigned long *)dst = 0;
 117
 118 #if !defined(__LITTLE_ENDIAN__)
 119                         dst += 4-count;
 120 #endif
 121                         if (ma->from(dst, srcu, count))
 122                                 goto fetch_fault;
 123
 124                         sign_extend(count, dst);
 125                 } else {
 126                         /* to memory */
 127                         src = (unsigned char *)rm;
 128 #if !defined(__LITTLE_ENDIAN__)
 129                         src += 4-count;
 130 #endif
 131                         dstu = (unsigned char __user *)*rn;
 132                         dstu += regs->regs[0];
 133
 134                         if (ma->to(dstu, src, count))
 135                                 goto fetch_fault;
 136                 }
 137                 ret = 0;
 138                 break;
 139
 140         case 1: /* mov.l Rm,@(disp,Rn) */
 141                 src = (unsigned char*) rm;
 142                 dstu = (unsigned char __user *)*rn;
 143                 dstu += (instruction&0x000F)<<2;
 144
 145                 if (ma->to(dstu, src, 4))
 146                         goto fetch_fault;
 147                 ret = 0;
 148                 break;
 149
 150         case 2: /* mov.[bwl] to memory, possibly with pre-decrement */
 151                 if (instruction & 4)
 152                         *rn -= count;
 153                 src = (unsigned char*) rm;
 154                 dstu = (unsigned char __user *)*rn;
 155 #if !defined(__LITTLE_ENDIAN__)
 156                 src += 4-count;
 157 #endif
 158                 if (ma->to(dstu, src, count))
 159                         goto fetch_fault;
 160                 ret = 0;
 161                 break;
 162
 163         case 5: /* mov.l @(disp,Rm),Rn */
 164                 srcu = (unsigned char __user *)*rm;
 165                 srcu += (instruction & 0x000F) << 2;
 166                 dst = (unsigned char *)rn;
 167                 *(unsigned long *)dst = 0;
 168
 169                 if (ma->from(dst, srcu, 4))
 170                         goto fetch_fault;
 171                 ret = 0;
 172                 break;
 173
 174         case 6: /* mov.[bwl] from memory, possibly with post-increment */
 175                 srcu = (unsigned char __user *)*rm;
 176                 if (instruction & 4)
 177                         *rm += count;
 178                 dst = (unsigned char*) rn;
 179                 *(unsigned long*)dst = 0;
 180
 181 #if !defined(__LITTLE_ENDIAN__)
 182                 dst += 4-count;
 183 #endif
 184                 if (ma->from(dst, srcu, count))
 185                         goto fetch_fault;
 186                 sign_extend(count, dst);
 187                 ret = 0;
 188                 break;
 189
 190         case 8:
 191                 switch ((instruction&0xFF00)>>8) {
 192                 case 0x81: /* mov.w R0,@(disp,Rn) */
 193                         src = (unsigned char *) &regs->regs[0];
 194 #if !defined(__LITTLE_ENDIAN__)
 195                         src += 2;
 196 #endif
 197                         dstu = (unsigned char __user *)*rm; /* called Rn in the spec */
 198                         dstu += (instruction & 0x000F) << 1;
 199
 200                         if (ma->to(dstu, src, 2))
 201                                 goto fetch_fault;
 202                         ret = 0;
 203                         break;
 204
 205                 case 0x85: /* mov.w @(disp,Rm),R0 */
 206                         srcu = (unsigned char __user *)*rm;
 207                         srcu += (instruction & 0x000F) << 1;
 208                         dst = (unsigned char *) &regs->regs[0];
 209                         *(unsigned long *)dst = 0;
 210
 211 #if !defined(__LITTLE_ENDIAN__)
 212                         dst += 2;
 213 #endif
 214                         if (ma->from(dst, srcu, 2))
 215                                 goto fetch_fault;
 216                         sign_extend(2, dst);
 217                         ret = 0;
 218                         break;
 219                 }
 220                 break;
 221
 222         case 9: /* mov.w @(disp,PC),Rn */
 223                 srcu = (unsigned char __user *)regs->pc;
 224                 srcu += 4;
 225                 srcu += (instruction & 0x00FF) << 1;
 226                 dst = (unsigned char *)rn;
 227                 *(unsigned long *)dst = 0;
 228
 229 #if !defined(__LITTLE_ENDIAN__)
 230                 dst += 2;
 231 #endif
 232
 233                 if (ma->from(dst, srcu, 2))
 234                         goto fetch_fault;
 235                 sign_extend(2, dst);
 236                 ret = 0;
 237                 break;
 238
 239         case 0xd: /* mov.l @(disp,PC),Rn */
 240                 srcu = (unsigned char __user *)(regs->pc & ~0x3);
 241                 srcu += 4;
 242                 srcu += (instruction & 0x00FF) << 2;
 243                 dst = (unsigned char *)rn;
 244                 *(unsigned long *)dst = 0;
 245
 246                 if (ma->from(dst, srcu, 4))
 247                         goto fetch_fault;
 248                 ret = 0;
 249                 break;
 250         }
 251         return ret;
 252
 253  fetch_fault:
 254         /* Argh. Address not only misaligned but also non-existent.
 255          * Raise an EFAULT and see if it's trapped
 256          */
 257         die_if_no_fixup("Fault in unaligned fixup", regs, 0);
 258         return -EFAULT;
 259 }
 260
 261 /*
 262  * emulate the instruction in the delay slot
 263  * - fetches the instruction from PC+2
 264  */
 265 static inline int handle_delayslot(struct pt_regs *regs,
 266                                    insn_size_t old_instruction,
 267                                    struct mem_access *ma)
 268 {
 269         insn_size_t instruction;
 270         void __user *addr = (void __user *)(regs->pc +
 271                 instruction_size(old_instruction));
 272
 273         if (copy_from_user(&instruction, addr, sizeof(instruction))) {
 274                 /* the instruction-fetch faulted */
 275                 if (user_mode(regs))
 276                         return -EFAULT;
 277
 278                 /* kernel */
 279                 die("delay-slot-insn faulting in handle_unaligned_delayslot",
 280                     regs, 0);
 281         }
 282
 283         return handle_unaligned_ins(instruction, regs, ma);
 284 }
 285
 286 /*
 287  * handle an instruction that does an unaligned memory access
 288  * - have to be careful of branch delay-slot instructions that fault
 289  *  SH3:
 290  *   - if the branch would be taken PC points to the branch
 291  *   - if the branch would not be taken, PC points to delay-slot
 292  *  SH4:
 293  *   - PC always points to delayed branch
 294  * - return 0 if handled, -EFAULT if failed (may not return if in kernel)
 295  */
 296
 297 /* Macros to determine offset from current PC for branch instructions */
 298 /* Explicit type coercion is used to force sign extension where needed */
 299 #define SH_PC_8BIT_OFFSET(instr) ((((signed char)(instr))*2) + 4)
 300 #define SH_PC_12BIT_OFFSET(instr) ((((signed short)(instr<<4))>>3) + 4)
 301
 302 int handle_unaligned_access(insn_size_t instruction, struct pt_regs *regs,
 303                             struct mem_access *ma, int expected,
 304                             unsigned long address)
 305 {
 306         u_int rm;
 307         int ret, index;
 308
 309         /*
 310          * XXX: We can't handle mixed 16/32-bit instructions yet
 311          */
 312         if (instruction_size(instruction) != 2)
 313                 return -EINVAL;
 314
 315         index = (instruction>>8)&15;    /* 0x0F00 */
 316         rm = regs->regs[index];
 317
 318         /*
 319          * Log the unexpected fixups, and then pass them on to perf.
 320          *
 321          * We intentionally don't report the expected cases to perf as
 322          * otherwise the trapped I/O case will skew the results too much
 323          * to be useful.
 324          */
 325         if (!expected) {
 326                 unaligned_fixups_notify(current, instruction, regs);
 327                 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1,
 328                               regs, address);
 329         }
 330
 331         ret = -EFAULT;
 332         switch (instruction&0xF000) {
 333         case 0x0000:
 334                 if (instruction==0x000B) {
 335                         /* rts */
 336                         ret = handle_delayslot(regs, instruction, ma);
 337                         if (ret==0)
 338                                 regs->pc = regs->pr;
 339                 }
 340                 else if ((instruction&0x00FF)==0x0023) {
 341                         /* braf @Rm */
 342                         ret = handle_delayslot(regs, instruction, ma);
 343                         if (ret==0)
 344                                 regs->pc += rm + 4;
 345                 }
 346                 else if ((instruction&0x00FF)==0x0003) {
 347                         /* bsrf @Rm */
 348                         ret = handle_delayslot(regs, instruction, ma);
 349                         if (ret==0) {
 350                                 regs->pr = regs->pc + 4;
 351                                 regs->pc += rm + 4;
 352                         }
 353                 }
 354                 else {
 355                         /* mov.[bwl] to/from memory via r0+rn */
 356                         goto simple;
 357                 }
 358                 break;
 359
 360         case 0x1000: /* mov.l Rm,@(disp,Rn) */
 361                 goto simple;
 362
 363         case 0x2000: /* mov.[bwl] to memory, possibly with pre-decrement */
 364                 goto simple;
 365
 366         case 0x4000:
 367                 if ((instruction&0x00FF)==0x002B) {
 368                         /* jmp @Rm */
 369                         ret = handle_delayslot(regs, instruction, ma);
 370                         if (ret==0)
 371                                 regs->pc = rm;
 372                 }
 373                 else if ((instruction&0x00FF)==0x000B) {
 374                         /* jsr @Rm */
 375                         ret = handle_delayslot(regs, instruction, ma);
 376                         if (ret==0) {
 377                                 regs->pr = regs->pc + 4;
 378                                 regs->pc = rm;
 379                         }
 380                 }
 381                 else {
 382                         /* mov.[bwl] to/from memory via r0+rn */
 383                         goto simple;
 384                 }
 385                 break;
 386
 387         case 0x5000: /* mov.l @(disp,Rm),Rn */
 388                 goto simple;
 389
 390         case 0x6000: /* mov.[bwl] from memory, possibly with post-increment */
 391                 goto simple;
 392
 393         case 0x8000: /* bf lab, bf/s lab, bt lab, bt/s lab */
 394                 switch (instruction&0x0F00) {
 395                 case 0x0100: /* mov.w R0,@(disp,Rm) */
 396                         goto simple;
 397                 case 0x0500: /* mov.w @(disp,Rm),R0 */
 398                         goto simple;
 399                 case 0x0B00: /* bf   lab - no delayslot*/
 400                         ret = 0;
 401                         break;
 402                 case 0x0F00: /* bf/s lab */
 403                         ret = handle_delayslot(regs, instruction, ma);
 404                         if (ret==0) {
 405 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
 406                                 if ((regs->sr & 0x00000001) != 0)
 407                                         regs->pc += 4; /* next after slot */
 408                                 else
 409 #endif
 410                                         regs->pc += SH_PC_8BIT_OFFSET(instruction);
 411                         }
 412                         break;
 413                 case 0x0900: /* bt   lab - no delayslot */
 414                         ret = 0;
 415                         break;
 416                 case 0x0D00: /* bt/s lab */
 417                         ret = handle_delayslot(regs, instruction, ma);
 418                         if (ret==0) {
 419 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
 420                                 if ((regs->sr & 0x00000001) == 0)
 421                                         regs->pc += 4; /* next after slot */
 422                                 else
 423 #endif
 424                                         regs->pc += SH_PC_8BIT_OFFSET(instruction);
 425                         }
 426                         break;
 427                 }
 428                 break;
 429
 430         case 0x9000: /* mov.w @(disp,Rm),Rn */
 431                 goto simple;
 432
 433         case 0xA000: /* bra label */
 434                 ret = handle_delayslot(regs, instruction, ma);
 435                 if (ret==0)
 436                         regs->pc += SH_PC_12BIT_OFFSET(instruction);
 437                 break;
 438
 439         case 0xB000: /* bsr label */
 440                 ret = handle_delayslot(regs, instruction, ma);
 441                 if (ret==0) {
 442                         regs->pr = regs->pc + 4;
 443                         regs->pc += SH_PC_12BIT_OFFSET(instruction);
 444                 }
 445                 break;
 446
 447         case 0xD000: /* mov.l @(disp,Rm),Rn */
 448                 goto simple;
 449         }
 450         return ret;
 451
 452         /* handle non-delay-slot instruction */
 453  simple:
 454         ret = handle_unaligned_ins(instruction, regs, ma);
 455         if (ret==0)
 456                 regs->pc += instruction_size(instruction);
 457         return ret;
 458 }
 459
 460 /*
 461  * Handle various address error exceptions:
 462  *  - instruction address error:
 463  *       misaligned PC
 464  *       PC >= 0x80000000 in user mode
 465  *  - data address error (read and write)
 466  *       misaligned data access
 467  *       access to >= 0x80000000 is user mode
 468  * Unfortuntaly we can't distinguish between instruction address error
 469  * and data address errors caused by read accesses.
 470  */
 471 asmlinkage void do_address_error(struct pt_regs *regs,
 472                                  unsigned long writeaccess,
 473                                  unsigned long address)
 474 {
 475         unsigned long error_code = 0;
 476         mm_segment_t oldfs;
 477         insn_size_t instruction;
 478         int tmp;
 479
 480         /* Intentional ifdef */
 481 #ifdef CONFIG_CPU_HAS_SR_RB
 482         error_code = lookup_exception_vector();
 483 #endif
 484
 485         oldfs = get_fs();
 486
 487         if (user_mode(regs)) {
 488                 int si_code = BUS_ADRERR;
 489                 unsigned int user_action;
 490
 491                 local_irq_enable();
 492                 inc_unaligned_user_access();
 493
 494                 set_fs(USER_DS);
 495                 if (copy_from_user(&instruction, (insn_size_t *)(regs->pc & ~1),
 496                                    sizeof(instruction))) {
 497                         set_fs(oldfs);
 498                         goto uspace_segv;
 499                 }
 500                 set_fs(oldfs);
 501
 502                 /* shout about userspace fixups */
 503                 unaligned_fixups_notify(current, instruction, regs);
 504
 505                 user_action = unaligned_user_action();
 506                 if (user_action & UM_FIXUP)
 507                         goto fixup;
 508                 if (user_action & UM_SIGNAL)
 509                         goto uspace_segv;
 510                 else {
 511                         /* ignore */
 512                         regs->pc += instruction_size(instruction);
 513                         return;
 514                 }
 515
 516 fixup:
 517                 /* bad PC is not something we can fix */
 518                 if (regs->pc & 1) {
 519                         si_code = BUS_ADRALN;
 520                         goto uspace_segv;
 521                 }
 522
 523                 set_fs(USER_DS);
 524                 tmp = handle_unaligned_access(instruction, regs,
 525                                               &user_mem_access, 0,
 526                                               address);
 527                 set_fs(oldfs);
 528
 529                 if (tmp == 0)
 530                         return; /* sorted */
 531 uspace_segv:
 532                 printk(KERN_NOTICE "Sending SIGBUS to \"%s\" due to unaligned "
 533                        "access (PC %lx PR %lx)\n", current->comm, regs->pc,
 534                        regs->pr);
 535
 536                 force_sig_fault(SIGBUS, si_code, (void __user *)address, current);
 537         } else {
 538                 inc_unaligned_kernel_access();
 539
 540                 if (regs->pc & 1)
 541                         die("unaligned program counter", regs, error_code);
 542
 543                 set_fs(KERNEL_DS);
 544                 if (copy_from_user(&instruction, (void __user *)(regs->pc),
 545                                    sizeof(instruction))) {
 546                         /* Argh. Fault on the instruction itself.
 547                            This should never happen non-SMP
 548                         */
 549                         set_fs(oldfs);
 550                         die("insn faulting in do_address_error", regs, 0);
 551                 }
 552
 553                 unaligned_fixups_notify(current, instruction, regs);
 554
 555                 handle_unaligned_access(instruction, regs, &user_mem_access,
 556                                         0, address);
 557                 set_fs(oldfs);
 558         }
 559 }
 560
 561 #ifdef CONFIG_SH_DSP
 562 /*
 563  *      SH-DSP support gerg@snapgear.com.
 564  */
 565 int is_dsp_inst(struct pt_regs *regs)
 566 {
 567         unsigned short inst = 0;
 568
 569         /*
 570          * Safe guard if DSP mode is already enabled or we're lacking
 571          * the DSP altogether.
 572          */
 573         if (!(current_cpu_data.flags & CPU_HAS_DSP) || (regs->sr & SR_DSP))
 574                 return 0;
 575
 576         get_user(inst, ((unsigned short *) regs->pc));
 577
 578         inst &= 0xf000;
 579
 580         /* Check for any type of DSP or support instruction */
 581         if ((inst == 0xf000) || (inst == 0x4000))
 582                 return 1;
 583
 584         return 0;
 585 }
 586 #else
 587 #define is_dsp_inst(regs)       (0)
 588 #endif /* CONFIG_SH_DSP */
 589
 590 #ifdef CONFIG_CPU_SH2A
 591 asmlinkage void do_divide_error(unsigned long r4)
 592 {
 593         int code;
 594
 595         switch (r4) {
 596         case TRAP_DIVZERO_ERROR:
 597                 code = FPE_INTDIV;
 598                 break;
 599         case TRAP_DIVOVF_ERROR:
 600                 code = FPE_INTOVF;
 601                 break;
 602         default:
 603                 /* Let gcc know unhandled cases don't make it past here */
 604                 return;
 605         }
 606         force_sig_fault(SIGFPE, code, NULL, current);
 607 }
 608 #endif
 609
 610 asmlinkage void do_reserved_inst(void)
 611 {
 612         struct pt_regs *regs = current_pt_regs();
 613         unsigned long error_code;
 614         struct task_struct *tsk = current;
 615
 616 #ifdef CONFIG_SH_FPU_EMU
 617         unsigned short inst = 0;
 618         int err;
 619
 620         get_user(inst, (unsigned short*)regs->pc);
 621
 622         err = do_fpu_inst(inst, regs);
 623         if (!err) {
 624                 regs->pc += instruction_size(inst);
 625                 return;
 626         }
 627         /* not a FPU inst. */
 628 #endif
 629
 630 #ifdef CONFIG_SH_DSP
 631         /* Check if it's a DSP instruction */
 632         if (is_dsp_inst(regs)) {
 633                 /* Enable DSP mode, and restart instruction. */
 634                 regs->sr |= SR_DSP;
 635                 /* Save DSP mode */
 636                 tsk->thread.dsp_status.status |= SR_DSP;
 637                 return;
 638         }
 639 #endif
 640
 641         error_code = lookup_exception_vector();
 642
 643         local_irq_enable();
 644         force_sig(SIGILL, tsk);
 645         die_if_no_fixup("reserved instruction", regs, error_code);
 646 }
 647
 648 #ifdef CONFIG_SH_FPU_EMU
 649 static int emulate_branch(unsigned short inst, struct pt_regs *regs)
 650 {
 651         /*
 652          * bfs: 8fxx: PC+=d*2+4;
 653          * bts: 8dxx: PC+=d*2+4;
 654          * bra: axxx: PC+=D*2+4;
 655          * bsr: bxxx: PC+=D*2+4  after PR=PC+4;
 656          * braf:0x23: PC+=Rn*2+4;
 657          * bsrf:0x03: PC+=Rn*2+4 after PR=PC+4;
 658          * jmp: 4x2b: PC=Rn;
 659          * jsr: 4x0b: PC=Rn      after PR=PC+4;
 660          * rts: 000b: PC=PR;
 661          */
 662         if (((inst & 0xf000) == 0xb000)  ||     /* bsr */
 663             ((inst & 0xf0ff) == 0x0003)  ||     /* bsrf */
 664             ((inst & 0xf0ff) == 0x400b))        /* jsr */
 665                 regs->pr = regs->pc + 4;
 666
 667         if ((inst & 0xfd00) == 0x8d00) {        /* bfs, bts */
 668                 regs->pc += SH_PC_8BIT_OFFSET(inst);
 669                 return 0;
 670         }
 671
 672         if ((inst & 0xe000) == 0xa000) {        /* bra, bsr */
 673                 regs->pc += SH_PC_12BIT_OFFSET(inst);
 674                 return 0;
 675         }
 676
 677         if ((inst & 0xf0df) == 0x0003) {        /* braf, bsrf */
 678                 regs->pc += regs->regs[(inst & 0x0f00) >> 8] + 4;
 679                 return 0;
 680         }
 681
 682         if ((inst & 0xf0df) == 0x400b) {        /* jmp, jsr */
 683                 regs->pc = regs->regs[(inst & 0x0f00) >> 8];
 684                 return 0;
 685         }
 686
 687         if ((inst & 0xffff) == 0x000b) {        /* rts */
 688                 regs->pc = regs->pr;
 689                 return 0;
 690         }
 691
 692         return 1;
 693 }
 694 #endif
 695
 696 asmlinkage void do_illegal_slot_inst(void)
 697 {
 698         struct pt_regs *regs = current_pt_regs();
 699         unsigned long inst;
 700         struct task_struct *tsk = current;
 701
 702         if (kprobe_handle_illslot(regs->pc) == 0)
 703                 return;
 704
 705 #ifdef CONFIG_SH_FPU_EMU
 706         get_user(inst, (unsigned short *)regs->pc + 1);
 707         if (!do_fpu_inst(inst, regs)) {
 708                 get_user(inst, (unsigned short *)regs->pc);
 709                 if (!emulate_branch(inst, regs))
 710                         return;
 711                 /* fault in branch.*/
 712         }
 713         /* not a FPU inst. */
 714 #endif
 715
 716         inst = lookup_exception_vector();
 717
 718         local_irq_enable();
 719         force_sig(SIGILL, tsk);
 720         die_if_no_fixup("illegal slot instruction", regs, inst);
 721 }
 722
 723 asmlinkage void do_exception_error(void)
 724 {
 725         long ex;
 726
 727         ex = lookup_exception_vector();
 728         die_if_kernel("exception", current_pt_regs(), ex);
 729 }
 730
 731 void per_cpu_trap_init(void)
 732 {
 733         extern void *vbr_base;
 734
 735         /* NOTE: The VBR value should be at P1
 736            (or P2, virtural "fixed" address space).
 737            It's definitely should not in physical address.  */
 738
 739         asm volatile("ldc       %0, vbr"
 740                      : /* no output */
 741                      : "r" (&vbr_base)
 742                      : "memory");
 743
 744         /* disable exception blocking now when the vbr has been setup */
 745         clear_bl_bit();
 746 }
 747
 748 void *set_exception_table_vec(unsigned int vec, void *handler)
 749 {
 750         extern void *exception_handling_table[];
 751         void *old_handler;
 752
 753         old_handler = exception_handling_table[vec];
 754         exception_handling_table[vec] = handler;
 755         return old_handler;
 756 }
 757
 758 void __init trap_init(void)
 759 {
 760         set_exception_table_vec(TRAP_RESERVED_INST, do_reserved_inst);
 761         set_exception_table_vec(TRAP_ILLEGAL_SLOT_INST, do_illegal_slot_inst);
 762
 763 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SH_FPU) || \
 764     defined(CONFIG_SH_FPU_EMU)
 765         /*
 766          * For SH-4 lacking an FPU, treat floating point instructions as
 767          * reserved. They'll be handled in the math-emu case, or faulted on
 768          * otherwise.
 769          */
 770         set_exception_table_evt(0x800, do_reserved_inst);
 771         set_exception_table_evt(0x820, do_illegal_slot_inst);
 772 #elif defined(CONFIG_SH_FPU)
 773         set_exception_table_evt(0x800, fpu_state_restore_trap_handler);
 774         set_exception_table_evt(0x820, fpu_state_restore_trap_handler);
 775 #endif
 776
 777 #ifdef CONFIG_CPU_SH2
 778         set_exception_table_vec(TRAP_ADDRESS_ERROR, address_error_trap_handler);
 779 #endif
 780 #ifdef CONFIG_CPU_SH2A
 781         set_exception_table_vec(TRAP_DIVZERO_ERROR, do_divide_error);
 782         set_exception_table_vec(TRAP_DIVOVF_ERROR, do_divide_error);
 783 #ifdef CONFIG_SH_FPU
 784         set_exception_table_vec(TRAP_FPU_ERROR, fpu_error_trap_handler);
 785 #endif
 786 #endif
 787
 788 #ifdef TRAP_UBC
 789         set_exception_table_vec(TRAP_UBC, breakpoint_trap_handler);
 790 #endif
 791 }