arch/tile/kernel/single_step.c

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * A code-rewriter that enables instruction single-stepping.
  15  * Derived from iLib's single-stepping code.
  16  */
  17
  18 #ifndef __tilegx__   /* Hardware support for single step unavailable. */
  19
  20 /* These functions are only used on the TILE platform */
  21 #include <linux/slab.h>
  22 #include <linux/thread_info.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/mman.h>
  25 #include <linux/types.h>
  26 #include <linux/err.h>
  27 #include <asm/cacheflush.h>
  28 #include <asm/unaligned.h>
  29 #include <arch/abi.h>
  30 #include <arch/opcode.h>
  31
  32 #define signExtend17(val) sign_extend((val), 17)
  33 #define TILE_X1_MASK (0xffffffffULL << 31)
  34
  35 int unaligned_printk;
  36
  37 static int __init setup_unaligned_printk(char *str)
  38 {
  39         long val;
  40         if (strict_strtol(str, 0, &val) != 0)
  41                 return 0;
  42         unaligned_printk = val;
  43         pr_info("Printk for each unaligned data accesses is %s\n",
  44                 unaligned_printk ? "enabled" : "disabled");
  45         return 1;
  46 }
  47 __setup("unaligned_printk=", setup_unaligned_printk);
  48
  49 unsigned int unaligned_fixup_count;
  50
  51 enum mem_op {
  52         MEMOP_NONE,
  53         MEMOP_LOAD,
  54         MEMOP_STORE,
  55         MEMOP_LOAD_POSTINCR,
  56         MEMOP_STORE_POSTINCR
  57 };
  58
  59 static inline tile_bundle_bits set_BrOff_X1(tile_bundle_bits n, s32 offset)
  60 {
  61         tile_bundle_bits result;
  62
  63         /* mask out the old offset */
  64         tile_bundle_bits mask = create_BrOff_X1(-1);
  65         result = n & (~mask);
  66
  67         /* or in the new offset */
  68         result |= create_BrOff_X1(offset);
  69
  70         return result;
  71 }
  72
  73 static inline tile_bundle_bits move_X1(tile_bundle_bits n, int dest, int src)
  74 {
  75         tile_bundle_bits result;
  76         tile_bundle_bits op;
  77
  78         result = n & (~TILE_X1_MASK);
  79
  80         op = create_Opcode_X1(SPECIAL_0_OPCODE_X1) |
  81                 create_RRROpcodeExtension_X1(OR_SPECIAL_0_OPCODE_X1) |
  82                 create_Dest_X1(dest) |
  83                 create_SrcB_X1(TREG_ZERO) |
  84                 create_SrcA_X1(src) ;
  85
  86         result |= op;
  87         return result;
  88 }
  89
  90 static inline tile_bundle_bits nop_X1(tile_bundle_bits n)
  91 {
  92         return move_X1(n, TREG_ZERO, TREG_ZERO);
  93 }
  94
  95 static inline tile_bundle_bits addi_X1(
  96         tile_bundle_bits n, int dest, int src, int imm)
  97 {
  98         n &= ~TILE_X1_MASK;
  99
 100         n |=  (create_SrcA_X1(src) |
 101                create_Dest_X1(dest) |
 102                create_Imm8_X1(imm) |
 103                create_S_X1(0) |
 104                create_Opcode_X1(IMM_0_OPCODE_X1) |
 105                create_ImmOpcodeExtension_X1(ADDI_IMM_0_OPCODE_X1));
 106
 107         return n;
 108 }
 109
 110 static tile_bundle_bits rewrite_load_store_unaligned(
 111         struct single_step_state *state,
 112         tile_bundle_bits bundle,
 113         struct pt_regs *regs,
 114         enum mem_op mem_op,
 115         int size, int sign_ext)
 116 {
 117         unsigned char __user *addr;
 118         int val_reg, addr_reg, err, val;
 119
 120         /* Get address and value registers */
 121         if (bundle & TILEPRO_BUNDLE_Y_ENCODING_MASK) {
 122                 addr_reg = get_SrcA_Y2(bundle);
 123                 val_reg = get_SrcBDest_Y2(bundle);
 124         } else if (mem_op == MEMOP_LOAD || mem_op == MEMOP_LOAD_POSTINCR) {
 125                 addr_reg = get_SrcA_X1(bundle);
 126                 val_reg  = get_Dest_X1(bundle);
 127         } else {
 128                 addr_reg = get_SrcA_X1(bundle);
 129                 val_reg  = get_SrcB_X1(bundle);
 130         }
 131
 132         /*
 133          * If registers are not GPRs, don't try to handle it.
 134          *
 135          * FIXME: we could handle non-GPR loads by getting the real value
 136          * from memory, writing it to the single step buffer, using a
 137          * temp_reg to hold a pointer to that memory, then executing that
 138          * instruction and resetting temp_reg.  For non-GPR stores, it's a
 139          * little trickier; we could use the single step buffer for that
 140          * too, but we'd have to add some more state bits so that we could
 141          * call back in here to copy that value to the real target.  For
 142          * now, we just handle the simple case.
 143          */
 144         if ((val_reg >= PTREGS_NR_GPRS &&
 145              (val_reg != TREG_ZERO ||
 146               mem_op == MEMOP_LOAD ||
 147               mem_op == MEMOP_LOAD_POSTINCR)) ||
 148             addr_reg >= PTREGS_NR_GPRS)
 149                 return bundle;
 150
 151         /* If it's aligned, don't handle it specially */
 152         addr = (void __user *)regs->regs[addr_reg];
 153         if (((unsigned long)addr % size) == 0)
 154                 return bundle;
 155
 156         /*
 157          * Return SIGBUS with the unaligned address, if requested.
 158          * Note that we return SIGBUS even for completely invalid addresses
 159          * as long as they are in fact unaligned; this matches what the
 160          * tilepro hardware would be doing, if it could provide us with the
 161          * actual bad address in an SPR, which it doesn't.
 162          */
 163         if (unaligned_fixup == 0) {
 164                 siginfo_t info = {
 165                         .si_signo = SIGBUS,
 166                         .si_code = BUS_ADRALN,
 167                         .si_addr = addr
 168                 };
 169                 trace_unhandled_signal("unaligned trap", regs,
 170                                        (unsigned long)addr, SIGBUS);
 171                 force_sig_info(info.si_signo, &info, current);
 172                 return (tilepro_bundle_bits) 0;
 173         }
 174
 175 #ifndef __LITTLE_ENDIAN
 176 # error We assume little-endian representation with copy_xx_user size 2 here
 177 #endif
 178         /* Handle unaligned load/store */
 179         if (mem_op == MEMOP_LOAD || mem_op == MEMOP_LOAD_POSTINCR) {
 180                 unsigned short val_16;
 181                 switch (size) {
 182                 case 2:
 183                         err = copy_from_user(&val_16, addr, sizeof(val_16));
 184                         val = sign_ext ? ((short)val_16) : val_16;
 185                         break;
 186                 case 4:
 187                         err = copy_from_user(&val, addr, sizeof(val));
 188                         break;
 189                 default:
 190                         BUG();
 191                 }
 192                 if (err == 0) {
 193                         state->update_reg = val_reg;
 194                         state->update_value = val;
 195                         state->update = 1;
 196                 }
 197         } else {
 198                 val = (val_reg == TREG_ZERO) ? 0 : regs->regs[val_reg];
 199                 err = copy_to_user(addr, &val, size);
 200         }
 201
 202         if (err) {
 203                 siginfo_t info = {
 204                         .si_signo = SIGSEGV,
 205                         .si_code = SEGV_MAPERR,
 206                         .si_addr = addr
 207                 };
 208                 trace_unhandled_signal("segfault", regs,
 209                                        (unsigned long)addr, SIGSEGV);
 210                 force_sig_info(info.si_signo, &info, current);
 211                 return (tile_bundle_bits) 0;
 212         }
 213
 214         if (unaligned_printk || unaligned_fixup_count == 0) {
 215                 pr_info("Process %d/%s: PC %#lx: Fixup of"
 216                         " unaligned %s at %#lx.\n",
 217                         current->pid, current->comm, regs->pc,
 218                         (mem_op == MEMOP_LOAD ||
 219                          mem_op == MEMOP_LOAD_POSTINCR) ?
 220                         "load" : "store",
 221                         (unsigned long)addr);
 222                 if (!unaligned_printk) {
 223 #define P pr_info
 224 P("\n");
 225 P("Unaligned fixups in the kernel will slow your application considerably.\n");
 226 P("To find them, write a \"1\" to /proc/sys/tile/unaligned_fixup/printk,\n");
 227 P("which requests the kernel show all unaligned fixups, or write a \"0\"\n");
 228 P("to /proc/sys/tile/unaligned_fixup/enabled, in which case each unaligned\n");
 229 P("access will become a SIGBUS you can debug. No further warnings will be\n");
 230 P("shown so as to avoid additional slowdown, but you can track the number\n");
 231 P("of fixups performed via /proc/sys/tile/unaligned_fixup/count.\n");
 232 P("Use the tile-addr2line command (see \"info addr2line\") to decode PCs.\n");
 233 P("\n");
 234 #undef P
 235                 }
 236         }
 237         ++unaligned_fixup_count;
 238
 239         if (bundle & TILEPRO_BUNDLE_Y_ENCODING_MASK) {
 240                 /* Convert the Y2 instruction to a prefetch. */
 241                 bundle &= ~(create_SrcBDest_Y2(-1) |
 242                             create_Opcode_Y2(-1));
 243                 bundle |= (create_SrcBDest_Y2(TREG_ZERO) |
 244                            create_Opcode_Y2(LW_OPCODE_Y2));
 245         /* Replace the load postincr with an addi */
 246         } else if (mem_op == MEMOP_LOAD_POSTINCR) {
 247                 bundle = addi_X1(bundle, addr_reg, addr_reg,
 248                                  get_Imm8_X1(bundle));
 249         /* Replace the store postincr with an addi */
 250         } else if (mem_op == MEMOP_STORE_POSTINCR) {
 251                 bundle = addi_X1(bundle, addr_reg, addr_reg,
 252                                  get_Dest_Imm8_X1(bundle));
 253         } else {
 254                 /* Convert the X1 instruction to a nop. */
 255                 bundle &= ~(create_Opcode_X1(-1) |
 256                             create_UnShOpcodeExtension_X1(-1) |
 257                             create_UnOpcodeExtension_X1(-1));
 258                 bundle |= (create_Opcode_X1(SHUN_0_OPCODE_X1) |
 259                            create_UnShOpcodeExtension_X1(
 260                                    UN_0_SHUN_0_OPCODE_X1) |
 261                            create_UnOpcodeExtension_X1(
 262                                    NOP_UN_0_SHUN_0_OPCODE_X1));
 263         }
 264
 265         return bundle;
 266 }
 267
 268 /*
 269  * Called after execve() has started the new image.  This allows us
 270  * to reset the info state.  Note that the the mmap'ed memory, if there
 271  * was any, has already been unmapped by the exec.
 272  */
 273 void single_step_execve(void)
 274 {
 275         struct thread_info *ti = current_thread_info();
 276         kfree(ti->step_state);
 277         ti->step_state = NULL;
 278 }
 279
 280 /**
 281  * single_step_once() - entry point when single stepping has been triggered.
 282  * @regs: The machine register state
 283  *
 284  *  When we arrive at this routine via a trampoline, the single step
 285  *  engine copies the executing bundle to the single step buffer.
 286  *  If the instruction is a condition branch, then the target is
 287  *  reset to one past the next instruction. If the instruction
 288  *  sets the lr, then that is noted. If the instruction is a jump
 289  *  or call, then the new target pc is preserved and the current
 290  *  bundle instruction set to null.
 291  *
 292  *  The necessary post-single-step rewriting information is stored in
 293  *  single_step_state->  We use data segment values because the
 294  *  stack will be rewound when we run the rewritten single-stepped
 295  *  instruction.
 296  */
 297 void single_step_once(struct pt_regs *regs)
 298 {
 299         extern tile_bundle_bits __single_step_ill_insn;
 300         extern tile_bundle_bits __single_step_j_insn;
 301         extern tile_bundle_bits __single_step_addli_insn;
 302         extern tile_bundle_bits __single_step_auli_insn;
 303         struct thread_info *info = (void *)current_thread_info();
 304         struct single_step_state *state = info->step_state;
 305         int is_single_step = test_ti_thread_flag(info, TIF_SINGLESTEP);
 306         tile_bundle_bits __user *buffer, *pc;
 307         tile_bundle_bits bundle;
 308         int temp_reg;
 309         int target_reg = TREG_LR;
 310         int err;
 311         enum mem_op mem_op = MEMOP_NONE;
 312         int size = 0, sign_ext = 0;  /* happy compiler */
 313
 314         asm(
 315 "    .pushsection .rodata.single_step\n"
 316 "    .align 8\n"
 317 "    .globl    __single_step_ill_insn\n"
 318 "__single_step_ill_insn:\n"
 319 "    ill\n"
 320 "    .globl    __single_step_addli_insn\n"
 321 "__single_step_addli_insn:\n"
 322 "    { nop; addli r0, zero, 0 }\n"
 323 "    .globl    __single_step_auli_insn\n"
 324 "__single_step_auli_insn:\n"
 325 "    { nop; auli r0, r0, 0 }\n"
 326 "    .globl    __single_step_j_insn\n"
 327 "__single_step_j_insn:\n"
 328 "    j .\n"
 329 "    .popsection\n"
 330         );
 331
 332         /*
 333          * Enable interrupts here to allow touching userspace and the like.
 334          * The callers expect this: do_trap() already has interrupts
 335          * enabled, and do_work_pending() handles functions that enable
 336          * interrupts internally.
 337          */
 338         local_irq_enable();
 339
 340         if (state == NULL) {
 341                 /* allocate a page of writable, executable memory */
 342                 state = kmalloc(sizeof(struct single_step_state), GFP_KERNEL);
 343                 if (state == NULL) {
 344                         pr_err("Out of kernel memory trying to single-step\n");
 345                         return;
 346                 }
 347
 348                 /* allocate a cache line of writable, executable memory */
 349                 down_write(&current->mm->mmap_sem);
 350                 buffer = (void __user *) do_mmap(NULL, 0, 64,
 351                                           PROT_EXEC | PROT_READ | PROT_WRITE,
 352                                           MAP_PRIVATE | MAP_ANONYMOUS,
 353                                           0);
 354                 up_write(&current->mm->mmap_sem);
 355
 356                 if (IS_ERR((void __force *)buffer)) {
 357                         kfree(state);
 358                         pr_err("Out of kernel pages trying to single-step\n");
 359                         return;
 360                 }
 361
 362                 state->buffer = buffer;
 363                 state->is_enabled = 0;
 364
 365                 info->step_state = state;
 366
 367                 /* Validate our stored instruction patterns */
 368                 BUG_ON(get_Opcode_X1(__single_step_addli_insn) !=
 369                        ADDLI_OPCODE_X1);
 370                 BUG_ON(get_Opcode_X1(__single_step_auli_insn) !=
 371                        AULI_OPCODE_X1);
 372                 BUG_ON(get_SrcA_X1(__single_step_addli_insn) != TREG_ZERO);
 373                 BUG_ON(get_Dest_X1(__single_step_addli_insn) != 0);
 374                 BUG_ON(get_JOffLong_X1(__single_step_j_insn) != 0);
 375         }
 376
 377         /*
 378          * If we are returning from a syscall, we still haven't hit the
 379          * "ill" for the swint1 instruction.  So back the PC up to be
 380          * pointing at the swint1, but we'll actually return directly
 381          * back to the "ill" so we come back in via SIGILL as if we
 382          * had "executed" the swint1 without ever being in kernel space.
 383          */
 384         if (regs->faultnum == INT_SWINT_1)
 385                 regs->pc -= 8;
 386
 387         pc = (tile_bundle_bits __user *)(regs->pc);
 388         if (get_user(bundle, pc) != 0) {
 389                 pr_err("Couldn't read instruction at %p trying to step\n", pc);
 390                 return;
 391         }
 392
 393         /* We'll follow the instruction with 2 ill op bundles */
 394         state->orig_pc = (unsigned long)pc;
 395         state->next_pc = (unsigned long)(pc + 1);
 396         state->branch_next_pc = 0;
 397         state->update = 0;
 398
 399         if (!(bundle & TILEPRO_BUNDLE_Y_ENCODING_MASK)) {
 400                 /* two wide, check for control flow */
 401                 int opcode = get_Opcode_X1(bundle);
 402
 403                 switch (opcode) {
 404                 /* branches */
 405                 case BRANCH_OPCODE_X1:
 406                 {
 407                         s32 offset = signExtend17(get_BrOff_X1(bundle));
 408
 409                         /*
 410                          * For branches, we use a rewriting trick to let the
 411                          * hardware evaluate whether the branch is taken or
 412                          * untaken.  We record the target offset and then
 413                          * rewrite the branch instruction to target 1 insn
 414                          * ahead if the branch is taken.  We then follow the
 415                          * rewritten branch with two bundles, each containing
 416                          * an "ill" instruction. The supervisor examines the
 417                          * pc after the single step code is executed, and if
 418                          * the pc is the first ill instruction, then the
 419                          * branch (if any) was not taken.  If the pc is the
 420                          * second ill instruction, then the branch was
 421                          * taken. The new pc is computed for these cases, and
 422                          * inserted into the registers for the thread.  If
 423                          * the pc is the start of the single step code, then
 424                          * an exception or interrupt was taken before the
 425                          * code started processing, and the same "original"
 426                          * pc is restored.  This change, different from the
 427                          * original implementation, has the advantage of
 428                          * executing a single user instruction.
 429                          */
 430                         state->branch_next_pc = (unsigned long)(pc + offset);
 431
 432                         /* rewrite branch offset to go forward one bundle */
 433                         bundle = set_BrOff_X1(bundle, 2);
 434                 }
 435                 break;
 436
 437                 /* jumps */
 438                 case JALB_OPCODE_X1:
 439                 case JALF_OPCODE_X1:
 440                         state->update = 1;
 441                         state->next_pc =
 442                                 (unsigned long) (pc + get_JOffLong_X1(bundle));
 443                         break;
 444
 445                 case JB_OPCODE_X1:
 446                 case JF_OPCODE_X1:
 447                         state->next_pc =
 448                                 (unsigned long) (pc + get_JOffLong_X1(bundle));
 449                         bundle = nop_X1(bundle);
 450                         break;
 451
 452                 case SPECIAL_0_OPCODE_X1:
 453                         switch (get_RRROpcodeExtension_X1(bundle)) {
 454                         /* jump-register */
 455                         case JALRP_SPECIAL_0_OPCODE_X1:
 456                         case JALR_SPECIAL_0_OPCODE_X1:
 457                                 state->update = 1;
 458                                 state->next_pc =
 459                                         regs->regs[get_SrcA_X1(bundle)];
 460                                 break;
 461
 462                         case JRP_SPECIAL_0_OPCODE_X1:
 463                         case JR_SPECIAL_0_OPCODE_X1:
 464                                 state->next_pc =
 465                                         regs->regs[get_SrcA_X1(bundle)];
 466                                 bundle = nop_X1(bundle);
 467                                 break;
 468
 469                         case LNK_SPECIAL_0_OPCODE_X1:
 470                                 state->update = 1;
 471                                 target_reg = get_Dest_X1(bundle);
 472                                 break;
 473
 474                         /* stores */
 475                         case SH_SPECIAL_0_OPCODE_X1:
 476                                 mem_op = MEMOP_STORE;
 477                                 size = 2;
 478                                 break;
 479
 480                         case SW_SPECIAL_0_OPCODE_X1:
 481                                 mem_op = MEMOP_STORE;
 482                                 size = 4;
 483                                 break;
 484                         }
 485                         break;
 486
 487                 /* loads and iret */
 488                 case SHUN_0_OPCODE_X1:
 489                         if (get_UnShOpcodeExtension_X1(bundle) ==
 490                             UN_0_SHUN_0_OPCODE_X1) {
 491                                 switch (get_UnOpcodeExtension_X1(bundle)) {
 492                                 case LH_UN_0_SHUN_0_OPCODE_X1:
 493                                         mem_op = MEMOP_LOAD;
 494                                         size = 2;
 495                                         sign_ext = 1;
 496                                         break;
 497
 498                                 case LH_U_UN_0_SHUN_0_OPCODE_X1:
 499                                         mem_op = MEMOP_LOAD;
 500                                         size = 2;
 501                                         sign_ext = 0;
 502                                         break;
 503
 504                                 case LW_UN_0_SHUN_0_OPCODE_X1:
 505                                         mem_op = MEMOP_LOAD;
 506                                         size = 4;
 507                                         break;
 508
 509                                 case IRET_UN_0_SHUN_0_OPCODE_X1:
 510                                 {
 511                                         unsigned long ex0_0 = __insn_mfspr(
 512                                                 SPR_EX_CONTEXT_0_0);
 513                                         unsigned long ex0_1 = __insn_mfspr(
 514                                                 SPR_EX_CONTEXT_0_1);
 515                                         /*
 516                                          * Special-case it if we're iret'ing
 517                                          * to PL0 again.  Otherwise just let
 518                                          * it run and it will generate SIGILL.
 519                                          */
 520                                         if (EX1_PL(ex0_1) == USER_PL) {
 521                                                 state->next_pc = ex0_0;
 522                                                 regs->ex1 = ex0_1;
 523                                                 bundle = nop_X1(bundle);
 524                                         }
 525                                 }
 526                                 }
 527                         }
 528                         break;
 529
 530 #if CHIP_HAS_WH64()
 531                 /* postincrement operations */
 532                 case IMM_0_OPCODE_X1:
 533                         switch (get_ImmOpcodeExtension_X1(bundle)) {
 534                         case LWADD_IMM_0_OPCODE_X1:
 535                                 mem_op = MEMOP_LOAD_POSTINCR;
 536                                 size = 4;
 537                                 break;
 538
 539                         case LHADD_IMM_0_OPCODE_X1:
 540                                 mem_op = MEMOP_LOAD_POSTINCR;
 541                                 size = 2;
 542                                 sign_ext = 1;
 543                                 break;
 544
 545                         case LHADD_U_IMM_0_OPCODE_X1:
 546                                 mem_op = MEMOP_LOAD_POSTINCR;
 547                                 size = 2;
 548                                 sign_ext = 0;
 549                                 break;
 550
 551                         case SWADD_IMM_0_OPCODE_X1:
 552                                 mem_op = MEMOP_STORE_POSTINCR;
 553                                 size = 4;
 554                                 break;
 555
 556                         case SHADD_IMM_0_OPCODE_X1:
 557                                 mem_op = MEMOP_STORE_POSTINCR;
 558                                 size = 2;
 559                                 break;
 560
 561                         default:
 562                                 break;
 563                         }
 564                         break;
 565 #endif /* CHIP_HAS_WH64() */
 566                 }
 567
 568                 if (state->update) {
 569                         /*
 570                          * Get an available register.  We start with a
 571                          * bitmask with 1's for available registers.
 572                          * We truncate to the low 32 registers since
 573                          * we are guaranteed to have set bits in the
 574                          * low 32 bits, then use ctz to pick the first.
 575                          */
 576                         u32 mask = (u32) ~((1ULL << get_Dest_X0(bundle)) |
 577                                            (1ULL << get_SrcA_X0(bundle)) |
 578                                            (1ULL << get_SrcB_X0(bundle)) |
 579                                            (1ULL << target_reg));
 580                         temp_reg = __builtin_ctz(mask);
 581                         state->update_reg = temp_reg;
 582                         state->update_value = regs->regs[temp_reg];
 583                         regs->regs[temp_reg] = (unsigned long) (pc+1);
 584                         regs->flags |= PT_FLAGS_RESTORE_REGS;
 585                         bundle = move_X1(bundle, target_reg, temp_reg);
 586                 }
 587         } else {
 588                 int opcode = get_Opcode_Y2(bundle);
 589
 590                 switch (opcode) {
 591                 /* loads */
 592                 case LH_OPCODE_Y2:
 593                         mem_op = MEMOP_LOAD;
 594                         size = 2;
 595                         sign_ext = 1;
 596                         break;
 597
 598                 case LH_U_OPCODE_Y2:
 599                         mem_op = MEMOP_LOAD;
 600                         size = 2;
 601                         sign_ext = 0;
 602                         break;
 603
 604                 case LW_OPCODE_Y2:
 605                         mem_op = MEMOP_LOAD;
 606                         size = 4;
 607                         break;
 608
 609                 /* stores */
 610                 case SH_OPCODE_Y2:
 611                         mem_op = MEMOP_STORE;
 612                         size = 2;
 613                         break;
 614
 615                 case SW_OPCODE_Y2:
 616                         mem_op = MEMOP_STORE;
 617                         size = 4;
 618                         break;
 619                 }
 620         }
 621
 622         /*
 623          * Check if we need to rewrite an unaligned load/store.
 624          * Returning zero is a special value meaning we need to SIGSEGV.
 625          */
 626         if (mem_op != MEMOP_NONE && unaligned_fixup >= 0) {
 627                 bundle = rewrite_load_store_unaligned(state, bundle, regs,
 628                                                       mem_op, size, sign_ext);
 629                 if (bundle == 0)
 630                         return;
 631         }
 632
 633         /* write the bundle to our execution area */
 634         buffer = state->buffer;
 635         err = __put_user(bundle, buffer++);
 636
 637         /*
 638          * If we're really single-stepping, we take an INT_ILL after.
 639          * If we're just handling an unaligned access, we can just
 640          * jump directly back to where we were in user code.
 641          */
 642         if (is_single_step) {
 643                 err |= __put_user(__single_step_ill_insn, buffer++);
 644                 err |= __put_user(__single_step_ill_insn, buffer++);
 645         } else {
 646                 long delta;
 647
 648                 if (state->update) {
 649                         /* We have some state to update; do it inline */
 650                         int ha16;
 651                         bundle = __single_step_addli_insn;
 652                         bundle |= create_Dest_X1(state->update_reg);
 653                         bundle |= create_Imm16_X1(state->update_value);
 654                         err |= __put_user(bundle, buffer++);
 655                         bundle = __single_step_auli_insn;
 656                         bundle |= create_Dest_X1(state->update_reg);
 657                         bundle |= create_SrcA_X1(state->update_reg);
 658                         ha16 = (state->update_value + 0x8000) >> 16;
 659                         bundle |= create_Imm16_X1(ha16);
 660                         err |= __put_user(bundle, buffer++);
 661                         state->update = 0;
 662                 }
 663
 664                 /* End with a jump back to the next instruction */
 665                 delta = ((regs->pc + TILE_BUNDLE_SIZE_IN_BYTES) -
 666                         (unsigned long)buffer) >>
 667                         TILE_LOG2_BUNDLE_ALIGNMENT_IN_BYTES;
 668                 bundle = __single_step_j_insn;
 669                 bundle |= create_JOffLong_X1(delta);
 670                 err |= __put_user(bundle, buffer++);
 671         }
 672
 673         if (err) {
 674                 pr_err("Fault when writing to single-step buffer\n");
 675                 return;
 676         }
 677
 678         /*
 679          * Flush the buffer.
 680          * We do a local flush only, since this is a thread-specific buffer.
 681          */
 682         __flush_icache_range((unsigned long)state->buffer,
 683                              (unsigned long)buffer);
 684
 685         /* Indicate enabled */
 686         state->is_enabled = is_single_step;
 687         regs->pc = (unsigned long)state->buffer;
 688
 689         /* Fault immediately if we are coming back from a syscall. */
 690         if (regs->faultnum == INT_SWINT_1)
 691                 regs->pc += 8;
 692 }
 693
 694 #else
 695 #include <linux/smp.h>
 696 #include <linux/ptrace.h>
 697 #include <arch/spr_def.h>
 698
 699 static DEFINE_PER_CPU(unsigned long, ss_saved_pc);
 700
 701
 702 /*
 703  * Called directly on the occasion of an interrupt.
 704  *
 705  * If the process doesn't have single step set, then we use this as an
 706  * opportunity to turn single step off.
 707  *
 708  * It has been mentioned that we could conditionally turn off single stepping
 709  * on each entry into the kernel and rely on single_step_once to turn it
 710  * on for the processes that matter (as we already do), but this
 711  * implementation is somewhat more efficient in that we muck with registers
 712  * once on a bum interrupt rather than on every entry into the kernel.
 713  *
 714  * If SINGLE_STEP_CONTROL_K has CANCELED set, then an interrupt occurred,
 715  * so we have to run through this process again before we can say that an
 716  * instruction has executed.
 717  *
 718  * swint will set CANCELED, but it's a legitimate instruction.  Fortunately
 719  * it changes the PC.  If it hasn't changed, then we know that the interrupt
 720  * wasn't generated by swint and we'll need to run this process again before
 721  * we can say an instruction has executed.
 722  *
 723  * If either CANCELED == 0 or the PC's changed, we send out SIGTRAPs and get
 724  * on with our lives.
 725  */
 726
 727 void gx_singlestep_handle(struct pt_regs *regs, int fault_num)
 728 {
 729         unsigned long *ss_pc = &__get_cpu_var(ss_saved_pc);
 730         struct thread_info *info = (void *)current_thread_info();
 731         int is_single_step = test_ti_thread_flag(info, TIF_SINGLESTEP);
 732         unsigned long control = __insn_mfspr(SPR_SINGLE_STEP_CONTROL_K);
 733
 734         if (is_single_step == 0) {
 735                 __insn_mtspr(SPR_SINGLE_STEP_EN_K_K, 0);
 736
 737         } else if ((*ss_pc != regs->pc) ||
 738                    (!(control & SPR_SINGLE_STEP_CONTROL_1__CANCELED_MASK))) {
 739
 740                 ptrace_notify(SIGTRAP);
 741                 control |= SPR_SINGLE_STEP_CONTROL_1__CANCELED_MASK;
 742                 control |= SPR_SINGLE_STEP_CONTROL_1__INHIBIT_MASK;
 743                 __insn_mtspr(SPR_SINGLE_STEP_CONTROL_K, control);
 744         }
 745 }
 746
 747
 748 /*
 749  * Called from need_singlestep.  Set up the control registers and the enable
 750  * register, then return back.
 751  */
 752
 753 void single_step_once(struct pt_regs *regs)
 754 {
 755         unsigned long *ss_pc = &__get_cpu_var(ss_saved_pc);
 756         unsigned long control = __insn_mfspr(SPR_SINGLE_STEP_CONTROL_K);
 757
 758         *ss_pc = regs->pc;
 759         control |= SPR_SINGLE_STEP_CONTROL_1__CANCELED_MASK;
 760         control |= SPR_SINGLE_STEP_CONTROL_1__INHIBIT_MASK;
 761         __insn_mtspr(SPR_SINGLE_STEP_CONTROL_K, control);
 762         __insn_mtspr(SPR_SINGLE_STEP_EN_K_K, 1 << USER_PL);
 763 }
 764
 765 void single_step_execve(void)
 766 {
 767         /* Nothing */
 768 }
 769
 770 #endif /* !__tilegx__ */