arch/ia64/kernel/kprobes.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Kernel Probes (KProbes)
   4  *  arch/ia64/kernel/kprobes.c
   5  *
   6  * Copyright (C) IBM Corporation, 2002, 2004
   7  * Copyright (C) Intel Corporation, 2005
   8  *
   9  * 2005-Apr     Rusty Lynch <[email protected]> and Anil S Keshavamurthy
  10  *              <[email protected]> adapted from i386
  11  */
  12
  13 #include <linux/kprobes.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/string.h>
  16 #include <linux/slab.h>
  17 #include <linux/preempt.h>
  18 #include <linux/extable.h>
  19 #include <linux/kdebug.h>
  20 #include <linux/pgtable.h>
  21
  22 #include <asm/sections.h>
  23 #include <asm/exception.h>
  24
  25 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
  26 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
  27
  28 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
  29
  30 enum instruction_type {A, I, M, F, B, L, X, u};
  31 static enum instruction_type bundle_encoding[32][3] = {
  32   { M, I, I },                          /* 00 */
  33   { M, I, I },                          /* 01 */
  34   { M, I, I },                          /* 02 */
  35   { M, I, I },                          /* 03 */
  36   { M, L, X },                          /* 04 */
  37   { M, L, X },                          /* 05 */
  38   { u, u, u },                          /* 06 */
  39   { u, u, u },                          /* 07 */
  40   { M, M, I },                          /* 08 */
  41   { M, M, I },                          /* 09 */
  42   { M, M, I },                          /* 0A */
  43   { M, M, I },                          /* 0B */
  44   { M, F, I },                          /* 0C */
  45   { M, F, I },                          /* 0D */
  46   { M, M, F },                          /* 0E */
  47   { M, M, F },                          /* 0F */
  48   { M, I, B },                          /* 10 */
  49   { M, I, B },                          /* 11 */
  50   { M, B, B },                          /* 12 */
  51   { M, B, B },                          /* 13 */
  52   { u, u, u },                          /* 14 */
  53   { u, u, u },                          /* 15 */
  54   { B, B, B },                          /* 16 */
  55   { B, B, B },                          /* 17 */
  56   { M, M, B },                          /* 18 */
  57   { M, M, B },                          /* 19 */
  58   { u, u, u },                          /* 1A */
  59   { u, u, u },                          /* 1B */
  60   { M, F, B },                          /* 1C */
  61   { M, F, B },                          /* 1D */
  62   { u, u, u },                          /* 1E */
  63   { u, u, u },                          /* 1F */
  64 };
  65
  66 /* Insert a long branch code */
  67 static void __kprobes set_brl_inst(void *from, void *to)
  68 {
  69         s64 rel = ((s64) to - (s64) from) >> 4;
  70         bundle_t *brl;
  71         brl = (bundle_t *) ((u64) from & ~0xf);
  72         brl->quad0.template = 0x05;     /* [MLX](stop) */
  73         brl->quad0.slot0 = NOP_M_INST;  /* nop.m 0x0 */
  74         brl->quad0.slot1_p0 = ((rel >> 20) & 0x7fffffffff) << 2;
  75         brl->quad1.slot1_p1 = (((rel >> 20) & 0x7fffffffff) << 2) >> (64 - 46);
  76         /* brl.cond.sptk.many.clr rel<<4 (qp=0) */
  77         brl->quad1.slot2 = BRL_INST(rel >> 59, rel & 0xfffff);
  78 }
  79
  80 /*
  81  * In this function we check to see if the instruction
  82  * is IP relative instruction and update the kprobe
  83  * inst flag accordingly
  84  */
  85 static void __kprobes update_kprobe_inst_flag(uint template, uint  slot,
  86                                               uint major_opcode,
  87                                               unsigned long kprobe_inst,
  88                                               struct kprobe *p)
  89 {
  90         p->ainsn.inst_flag = 0;
  91         p->ainsn.target_br_reg = 0;
  92         p->ainsn.slot = slot;
  93
  94         /* Check for Break instruction
  95          * Bits 37:40 Major opcode to be zero
  96          * Bits 27:32 X6 to be zero
  97          * Bits 32:35 X3 to be zero
  98          */
  99         if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
 100                 /* is a break instruction */
 101                 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
 102                 return;
 103         }
 104
 105         if (bundle_encoding[template][slot] == B) {
 106                 switch (major_opcode) {
 107                   case INDIRECT_CALL_OPCODE:
 108                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 109                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 110                         break;
 111                   case IP_RELATIVE_PREDICT_OPCODE:
 112                   case IP_RELATIVE_BRANCH_OPCODE:
 113                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 114                         break;
 115                   case IP_RELATIVE_CALL_OPCODE:
 116                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 117                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 118                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 119                         break;
 120                 }
 121         } else if (bundle_encoding[template][slot] == X) {
 122                 switch (major_opcode) {
 123                   case LONG_CALL_OPCODE:
 124                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 125                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 126                   break;
 127                 }
 128         }
 129         return;
 130 }
 131
 132 /*
 133  * In this function we check to see if the instruction
 134  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 135  * on which we are inserting kprobe is cmp instruction
 136  * with ctype as unc.
 137  */
 138 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
 139                                             uint major_opcode,
 140                                             unsigned long kprobe_inst)
 141 {
 142         cmp_inst_t cmp_inst;
 143         uint ctype_unc = 0;
 144
 145         if (!((bundle_encoding[template][slot] == I) ||
 146                 (bundle_encoding[template][slot] == M)))
 147                 goto out;
 148
 149         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 150                 (major_opcode == 0xE)))
 151                 goto out;
 152
 153         cmp_inst.l = kprobe_inst;
 154         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 155                 /* Integer compare - Register Register (A6 type)*/
 156                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 157                                 &&(cmp_inst.f.c == 1))
 158                         ctype_unc = 1;
 159         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 160                 /* Integer compare - Immediate Register (A8 type)*/
 161                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 162                         ctype_unc = 1;
 163         }
 164 out:
 165         return ctype_unc;
 166 }
 167
 168 /*
 169  * In this function we check to see if the instruction
 170  * on which we are inserting kprobe is supported.
 171  * Returns qp value if supported
 172  * Returns -EINVAL if unsupported
 173  */
 174 static int __kprobes unsupported_inst(uint template, uint  slot,
 175                                       uint major_opcode,
 176                                       unsigned long kprobe_inst,
 177                                       unsigned long addr)
 178 {
 179         int qp;
 180
 181         qp = kprobe_inst & 0x3f;
 182         if (is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst)) {
 183                 if (slot == 1 && qp)  {
 184                         printk(KERN_WARNING "Kprobes on cmp unc "
 185                                         "instruction on slot 1 at <0x%lx> "
 186                                         "is not supported\n", addr);
 187                         return -EINVAL;
 188
 189                 }
 190                 qp = 0;
 191         }
 192         else if (bundle_encoding[template][slot] == I) {
 193                 if (major_opcode == 0) {
 194                         /*
 195                          * Check for Integer speculation instruction
 196                          * - Bit 33-35 to be equal to 0x1
 197                          */
 198                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 199                                 printk(KERN_WARNING
 200                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 201                                                 addr);
 202                                 return -EINVAL;
 203                         }
 204                         /*
 205                          * IP relative mov instruction
 206                          *  - Bit 27-35 to be equal to 0x30
 207                          */
 208                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 209                                 printk(KERN_WARNING
 210                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 211                                                 addr);
 212                                 return -EINVAL;
 213
 214                         }
 215                 }
 216                 else if ((major_opcode == 5) && !(kprobe_inst & (0xFUl << 33)) &&
 217                                 (kprobe_inst & (0x1UL << 12))) {
 218                         /* test bit instructions, tbit,tnat,tf
 219                          * bit 33-36 to be equal to 0
 220                          * bit 12 to be equal to 1
 221                          */
 222                         if (slot == 1 && qp) {
 223                                 printk(KERN_WARNING "Kprobes on test bit "
 224                                                 "instruction on slot at <0x%lx> "
 225                                                 "is not supported\n", addr);
 226                                 return -EINVAL;
 227                         }
 228                         qp = 0;
 229                 }
 230         }
 231         else if (bundle_encoding[template][slot] == B) {
 232                 if (major_opcode == 7) {
 233                         /* IP-Relative Predict major code is 7 */
 234                         printk(KERN_WARNING "Kprobes on IP-Relative"
 235                                         "Predict is not supported\n");
 236                         return -EINVAL;
 237                 }
 238                 else if (major_opcode == 2) {
 239                         /* Indirect Predict, major code is 2
 240                          * bit 27-32 to be equal to 10 or 11
 241                          */
 242                         int x6=(kprobe_inst >> 27) & 0x3F;
 243                         if ((x6 == 0x10) || (x6 == 0x11)) {
 244                                 printk(KERN_WARNING "Kprobes on "
 245                                         "Indirect Predict is not supported\n");
 246                                 return -EINVAL;
 247                         }
 248                 }
 249         }
 250         /* kernel does not use float instruction, here for safety kprobe
 251          * will judge whether it is fcmp/flass/float approximation instruction
 252          */
 253         else if (unlikely(bundle_encoding[template][slot] == F)) {
 254                 if ((major_opcode == 4 || major_opcode == 5) &&
 255                                 (kprobe_inst  & (0x1 << 12))) {
 256                         /* fcmp/fclass unc instruction */
 257                         if (slot == 1 && qp) {
 258                                 printk(KERN_WARNING "Kprobes on fcmp/fclass "
 259                                         "instruction on slot at <0x%lx> "
 260                                         "is not supported\n", addr);
 261                                 return -EINVAL;
 262
 263                         }
 264                         qp = 0;
 265                 }
 266                 if ((major_opcode == 0 || major_opcode == 1) &&
 267                         (kprobe_inst & (0x1UL << 33))) {
 268                         /* float Approximation instruction */
 269                         if (slot == 1 && qp) {
 270                                 printk(KERN_WARNING "Kprobes on float Approx "
 271                                         "instr at <0x%lx> is not supported\n",
 272                                                 addr);
 273                                 return -EINVAL;
 274                         }
 275                         qp = 0;
 276                 }
 277         }
 278         return qp;
 279 }
 280
 281 /*
 282  * In this function we override the bundle with
 283  * the break instruction at the given slot.
 284  */
 285 static void __kprobes prepare_break_inst(uint template, uint  slot,
 286                                          uint major_opcode,
 287                                          unsigned long kprobe_inst,
 288                                          struct kprobe *p,
 289                                          int qp)
 290 {
 291         unsigned long break_inst = BREAK_INST;
 292         bundle_t *bundle = &p->opcode.bundle;
 293
 294         /*
 295          * Copy the original kprobe_inst qualifying predicate(qp)
 296          * to the break instruction
 297          */
 298         break_inst |= qp;
 299
 300         switch (slot) {
 301           case 0:
 302                 bundle->quad0.slot0 = break_inst;
 303                 break;
 304           case 1:
 305                 bundle->quad0.slot1_p0 = break_inst;
 306                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 307                 break;
 308           case 2:
 309                 bundle->quad1.slot2 = break_inst;
 310                 break;
 311         }
 312
 313         /*
 314          * Update the instruction flag, so that we can
 315          * emulate the instruction properly after we
 316          * single step on original instruction
 317          */
 318         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 319 }
 320
 321 static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
 322                 unsigned long *kprobe_inst, uint *major_opcode)
 323 {
 324         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 325         unsigned int template;
 326
 327         template = bundle->quad0.template;
 328
 329         switch (slot) {
 330           case 0:
 331                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 332                 *kprobe_inst = bundle->quad0.slot0;
 333                   break;
 334           case 1:
 335                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 336                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 337                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 338                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 339                 break;
 340           case 2:
 341                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 342                 *kprobe_inst = bundle->quad1.slot2;
 343                 break;
 344         }
 345 }
 346
 347 /* Returns non-zero if the addr is in the Interrupt Vector Table */
 348 static int __kprobes in_ivt_functions(unsigned long addr)
 349 {
 350         return (addr >= (unsigned long)__start_ivt_text
 351                 && addr < (unsigned long)__end_ivt_text);
 352 }
 353
 354 static int __kprobes valid_kprobe_addr(int template, int slot,
 355                                        unsigned long addr)
 356 {
 357         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 358                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
 359                                 "at 0x%lx\n", addr);
 360                 return -EINVAL;
 361         }
 362
 363         if (in_ivt_functions(addr)) {
 364                 printk(KERN_WARNING "Kprobes can't be inserted inside "
 365                                 "IVT functions at 0x%lx\n", addr);
 366                 return -EINVAL;
 367         }
 368
 369         return 0;
 370 }
 371
 372 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 373 {
 374         unsigned int i;
 375         i = atomic_add_return(1, &kcb->prev_kprobe_index);
 376         kcb->prev_kprobe[i-1].kp = kprobe_running();
 377         kcb->prev_kprobe[i-1].status = kcb->kprobe_status;
 378 }
 379
 380 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 381 {
 382         unsigned int i;
 383         i = atomic_read(&kcb->prev_kprobe_index);
 384         __this_cpu_write(current_kprobe, kcb->prev_kprobe[i-1].kp);
 385         kcb->kprobe_status = kcb->prev_kprobe[i-1].status;
 386         atomic_sub(1, &kcb->prev_kprobe_index);
 387 }
 388
 389 static void __kprobes set_current_kprobe(struct kprobe *p,
 390                         struct kprobe_ctlblk *kcb)
 391 {
 392         __this_cpu_write(current_kprobe, p);
 393 }
 394
 395 static void kretprobe_trampoline(void)
 396 {
 397 }
 398
 399 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 400 {
 401         regs->cr_iip = __kretprobe_trampoline_handler(regs, kretprobe_trampoline, NULL);
 402         /*
 403          * By returning a non-zero value, we are telling
 404          * kprobe_handler() that we don't want the post_handler
 405          * to run (and have re-enabled preemption)
 406          */
 407         return 1;
 408 }
 409
 410 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 411                                       struct pt_regs *regs)
 412 {
 413         ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 414         ri->fp = NULL;
 415
 416         /* Replace the return addr with trampoline addr */
 417         regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 418 }
 419
 420 /* Check the instruction in the slot is break */
 421 static int __kprobes __is_ia64_break_inst(bundle_t *bundle, uint slot)
 422 {
 423         unsigned int major_opcode;
 424         unsigned int template = bundle->quad0.template;
 425         unsigned long kprobe_inst;
 426
 427         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 428         if (slot == 1 && bundle_encoding[template][1] == L)
 429                 slot++;
 430
 431         /* Get Kprobe probe instruction at given slot*/
 432         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 433
 434         /* For break instruction,
 435          * Bits 37:40 Major opcode to be zero
 436          * Bits 27:32 X6 to be zero
 437          * Bits 32:35 X3 to be zero
 438          */
 439         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF)) {
 440                 /* Not a break instruction */
 441                 return 0;
 442         }
 443
 444         /* Is a break instruction */
 445         return 1;
 446 }
 447
 448 /*
 449  * In this function, we check whether the target bundle modifies IP or
 450  * it triggers an exception. If so, it cannot be boostable.
 451  */
 452 static int __kprobes can_boost(bundle_t *bundle, uint slot,
 453                                unsigned long bundle_addr)
 454 {
 455         unsigned int template = bundle->quad0.template;
 456
 457         do {
 458                 if (search_exception_tables(bundle_addr + slot) ||
 459                     __is_ia64_break_inst(bundle, slot))
 460                         return 0;       /* exception may occur in this bundle*/
 461         } while ((++slot) < 3);
 462         template &= 0x1e;
 463         if (template >= 0x10 /* including B unit */ ||
 464             template == 0x04 /* including X unit */ ||
 465             template == 0x06) /* undefined */
 466                 return 0;
 467
 468         return 1;
 469 }
 470
 471 /* Prepare long jump bundle and disables other boosters if need */
 472 static void __kprobes prepare_booster(struct kprobe *p)
 473 {
 474         unsigned long addr = (unsigned long)p->addr & ~0xFULL;
 475         unsigned int slot = (unsigned long)p->addr & 0xf;
 476         struct kprobe *other_kp;
 477
 478         if (can_boost(&p->ainsn.insn[0].bundle, slot, addr)) {
 479                 set_brl_inst(&p->ainsn.insn[1].bundle, (bundle_t *)addr + 1);
 480                 p->ainsn.inst_flag |= INST_FLAG_BOOSTABLE;
 481         }
 482
 483         /* disables boosters in previous slots */
 484         for (; addr < (unsigned long)p->addr; addr++) {
 485                 other_kp = get_kprobe((void *)addr);
 486                 if (other_kp)
 487                         other_kp->ainsn.inst_flag &= ~INST_FLAG_BOOSTABLE;
 488         }
 489 }
 490
 491 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 492 {
 493         unsigned long addr = (unsigned long) p->addr;
 494         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 495         unsigned long kprobe_inst=0;
 496         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 497         bundle_t *bundle;
 498         int qp;
 499
 500         bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
 501         template = bundle->quad0.template;
 502
 503         if(valid_kprobe_addr(template, slot, addr))
 504                 return -EINVAL;
 505
 506         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 507         if (slot == 1 && bundle_encoding[template][1] == L)
 508                 slot++;
 509
 510         /* Get kprobe_inst and major_opcode from the bundle */
 511         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 512
 513         qp = unsupported_inst(template, slot, major_opcode, kprobe_inst, addr);
 514         if (qp < 0)
 515                 return -EINVAL;
 516
 517         p->ainsn.insn = get_insn_slot();
 518         if (!p->ainsn.insn)
 519                 return -ENOMEM;
 520         memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
 521         memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
 522
 523         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p, qp);
 524
 525         prepare_booster(p);
 526
 527         return 0;
 528 }
 529
 530 void __kprobes arch_arm_kprobe(struct kprobe *p)
 531 {
 532         unsigned long arm_addr;
 533         bundle_t *src, *dest;
 534
 535         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
 536         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
 537         src = &p->opcode.bundle;
 538
 539         flush_icache_range((unsigned long)p->ainsn.insn,
 540                            (unsigned long)p->ainsn.insn +
 541                            sizeof(kprobe_opcode_t) * MAX_INSN_SIZE);
 542
 543         switch (p->ainsn.slot) {
 544                 case 0:
 545                         dest->quad0.slot0 = src->quad0.slot0;
 546                         break;
 547                 case 1:
 548                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
 549                         break;
 550                 case 2:
 551                         dest->quad1.slot2 = src->quad1.slot2;
 552                         break;
 553         }
 554         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 555 }
 556
 557 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 558 {
 559         unsigned long arm_addr;
 560         bundle_t *src, *dest;
 561
 562         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
 563         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
 564         /* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
 565         src = &p->ainsn.insn->bundle;
 566         switch (p->ainsn.slot) {
 567                 case 0:
 568                         dest->quad0.slot0 = src->quad0.slot0;
 569                         break;
 570                 case 1:
 571                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
 572                         break;
 573                 case 2:
 574                         dest->quad1.slot2 = src->quad1.slot2;
 575                         break;
 576         }
 577         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 578 }
 579
 580 void __kprobes arch_remove_kprobe(struct kprobe *p)
 581 {
 582         if (p->ainsn.insn) {
 583                 free_insn_slot(p->ainsn.insn,
 584                                p->ainsn.inst_flag & INST_FLAG_BOOSTABLE);
 585                 p->ainsn.insn = NULL;
 586         }
 587 }
 588 /*
 589  * We are resuming execution after a single step fault, so the pt_regs
 590  * structure reflects the register state after we executed the instruction
 591  * located in the kprobe (p->ainsn.insn->bundle).  We still need to adjust
 592  * the ip to point back to the original stack address. To set the IP address
 593  * to original stack address, handle the case where we need to fixup the
 594  * relative IP address and/or fixup branch register.
 595  */
 596 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 597 {
 598         unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
 599         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 600         unsigned long template;
 601         int slot = ((unsigned long)p->addr & 0xf);
 602
 603         template = p->ainsn.insn->bundle.quad0.template;
 604
 605         if (slot == 1 && bundle_encoding[template][1] == L)
 606                 slot = 2;
 607
 608         if (p->ainsn.inst_flag & ~INST_FLAG_BOOSTABLE) {
 609
 610                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 611                         /* Fix relative IP address */
 612                         regs->cr_iip = (regs->cr_iip - bundle_addr) +
 613                                         resume_addr;
 614                 }
 615
 616                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 617                 /*
 618                  * Fix target branch register, software convention is
 619                  * to use either b0 or b6 or b7, so just checking
 620                  * only those registers
 621                  */
 622                         switch (p->ainsn.target_br_reg) {
 623                         case 0:
 624                                 if ((regs->b0 == bundle_addr) ||
 625                                         (regs->b0 == bundle_addr + 0x10)) {
 626                                         regs->b0 = (regs->b0 - bundle_addr) +
 627                                                 resume_addr;
 628                                 }
 629                                 break;
 630                         case 6:
 631                                 if ((regs->b6 == bundle_addr) ||
 632                                         (regs->b6 == bundle_addr + 0x10)) {
 633                                         regs->b6 = (regs->b6 - bundle_addr) +
 634                                                 resume_addr;
 635                                 }
 636                                 break;
 637                         case 7:
 638                                 if ((regs->b7 == bundle_addr) ||
 639                                         (regs->b7 == bundle_addr + 0x10)) {
 640                                         regs->b7 = (regs->b7 - bundle_addr) +
 641                                                 resume_addr;
 642                                 }
 643                                 break;
 644                         } /* end switch */
 645                 }
 646                 goto turn_ss_off;
 647         }
 648
 649         if (slot == 2) {
 650                 if (regs->cr_iip == bundle_addr + 0x10) {
 651                         regs->cr_iip = resume_addr + 0x10;
 652                 }
 653         } else {
 654                 if (regs->cr_iip == bundle_addr) {
 655                         regs->cr_iip = resume_addr;
 656                 }
 657         }
 658
 659 turn_ss_off:
 660         /* Turn off Single Step bit */
 661         ia64_psr(regs)->ss = 0;
 662 }
 663
 664 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
 665 {
 666         unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
 667         unsigned long slot = (unsigned long)p->addr & 0xf;
 668
 669         /* single step inline if break instruction */
 670         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
 671                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
 672         else
 673                 regs->cr_iip = bundle_addr & ~0xFULL;
 674
 675         if (slot > 2)
 676                 slot = 0;
 677
 678         ia64_psr(regs)->ri = slot;
 679
 680         /* turn on single stepping */
 681         ia64_psr(regs)->ss = 1;
 682 }
 683
 684 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
 685 {
 686         unsigned int slot = ia64_psr(regs)->ri;
 687         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
 688         bundle_t bundle;
 689
 690         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
 691
 692         return __is_ia64_break_inst(&bundle, slot);
 693 }
 694
 695 static int __kprobes pre_kprobes_handler(struct die_args *args)
 696 {
 697         struct kprobe *p;
 698         int ret = 0;
 699         struct pt_regs *regs = args->regs;
 700         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 701         struct kprobe_ctlblk *kcb;
 702
 703         /*
 704          * We don't want to be preempted for the entire
 705          * duration of kprobe processing
 706          */
 707         preempt_disable();
 708         kcb = get_kprobe_ctlblk();
 709
 710         /* Handle recursion cases */
 711         if (kprobe_running()) {
 712                 p = get_kprobe(addr);
 713                 if (p) {
 714                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
 715                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
 716                                 ia64_psr(regs)->ss = 0;
 717                                 goto no_kprobe;
 718                         }
 719                         /* We have reentered the pre_kprobe_handler(), since
 720                          * another probe was hit while within the handler.
 721                          * We here save the original kprobes variables and
 722                          * just single step on the instruction of the new probe
 723                          * without calling any user handlers.
 724                          */
 725                         save_previous_kprobe(kcb);
 726                         set_current_kprobe(p, kcb);
 727                         kprobes_inc_nmissed_count(p);
 728                         prepare_ss(p, regs);
 729                         kcb->kprobe_status = KPROBE_REENTER;
 730                         return 1;
 731                 } else if (!is_ia64_break_inst(regs)) {
 732                         /* The breakpoint instruction was removed by
 733                          * another cpu right after we hit, no further
 734                          * handling of this interrupt is appropriate
 735                          */
 736                         ret = 1;
 737                         goto no_kprobe;
 738                 } else {
 739                         /* Not our break */
 740                         goto no_kprobe;
 741                 }
 742         }
 743
 744         p = get_kprobe(addr);
 745         if (!p) {
 746                 if (!is_ia64_break_inst(regs)) {
 747                         /*
 748                          * The breakpoint instruction was removed right
 749                          * after we hit it.  Another cpu has removed
 750                          * either a probepoint or a debugger breakpoint
 751                          * at this address.  In either case, no further
 752                          * handling of this interrupt is appropriate.
 753                          */
 754                         ret = 1;
 755
 756                 }
 757
 758                 /* Not one of our break, let kernel handle it */
 759                 goto no_kprobe;
 760         }
 761
 762         set_current_kprobe(p, kcb);
 763         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 764
 765         if (p->pre_handler && p->pre_handler(p, regs)) {
 766                 reset_current_kprobe();
 767                 preempt_enable_no_resched();
 768                 return 1;
 769         }
 770
 771 #if !defined(CONFIG_PREEMPTION)
 772         if (p->ainsn.inst_flag == INST_FLAG_BOOSTABLE && !p->post_handler) {
 773                 /* Boost up -- we can execute copied instructions directly */
 774                 ia64_psr(regs)->ri = p->ainsn.slot;
 775                 regs->cr_iip = (unsigned long)&p->ainsn.insn->bundle & ~0xFULL;
 776                 /* turn single stepping off */
 777                 ia64_psr(regs)->ss = 0;
 778
 779                 reset_current_kprobe();
 780                 preempt_enable_no_resched();
 781                 return 1;
 782         }
 783 #endif
 784         prepare_ss(p, regs);
 785         kcb->kprobe_status = KPROBE_HIT_SS;
 786         return 1;
 787
 788 no_kprobe:
 789         preempt_enable_no_resched();
 790         return ret;
 791 }
 792
 793 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
 794 {
 795         struct kprobe *cur = kprobe_running();
 796         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 797
 798         if (!cur)
 799                 return 0;
 800
 801         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 802                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 803                 cur->post_handler(cur, regs, 0);
 804         }
 805
 806         resume_execution(cur, regs);
 807
 808         /*Restore back the original saved kprobes variables and continue. */
 809         if (kcb->kprobe_status == KPROBE_REENTER) {
 810                 restore_previous_kprobe(kcb);
 811                 goto out;
 812         }
 813         reset_current_kprobe();
 814
 815 out:
 816         preempt_enable_no_resched();
 817         return 1;
 818 }
 819
 820 int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 821 {
 822         struct kprobe *cur = kprobe_running();
 823         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 824
 825
 826         switch(kcb->kprobe_status) {
 827         case KPROBE_HIT_SS:
 828         case KPROBE_REENTER:
 829                 /*
 830                  * We are here because the instruction being single
 831                  * stepped caused a page fault. We reset the current
 832                  * kprobe and the instruction pointer points back to
 833                  * the probe address and allow the page fault handler
 834                  * to continue as a normal page fault.
 835                  */
 836                 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
 837                 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
 838                 if (kcb->kprobe_status == KPROBE_REENTER)
 839                         restore_previous_kprobe(kcb);
 840                 else
 841                         reset_current_kprobe();
 842                 preempt_enable_no_resched();
 843                 break;
 844         case KPROBE_HIT_ACTIVE:
 845         case KPROBE_HIT_SSDONE:
 846                 /*
 847                  * We increment the nmissed count for accounting,
 848                  * we can also use npre/npostfault count for accounting
 849                  * these specific fault cases.
 850                  */
 851                 kprobes_inc_nmissed_count(cur);
 852
 853                 /*
 854                  * We come here because instructions in the pre/post
 855                  * handler caused the page_fault, this could happen
 856                  * if handler tries to access user space by
 857                  * copy_from_user(), get_user() etc. Let the
 858                  * user-specified handler try to fix it first.
 859                  */
 860                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 861                         return 1;
 862                 /*
 863                  * In case the user-specified fault handler returned
 864                  * zero, try to fix up.
 865                  */
 866                 if (ia64_done_with_exception(regs))
 867                         return 1;
 868
 869                 /*
 870                  * Let ia64_do_page_fault() fix it.
 871                  */
 872                 break;
 873         default:
 874                 break;
 875         }
 876
 877         return 0;
 878 }
 879
 880 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 881                                        unsigned long val, void *data)
 882 {
 883         struct die_args *args = (struct die_args *)data;
 884         int ret = NOTIFY_DONE;
 885
 886         if (args->regs && user_mode(args->regs))
 887                 return ret;
 888
 889         switch(val) {
 890         case DIE_BREAK:
 891                 /* err is break number from ia64_bad_break() */
 892                 if ((args->err >> 12) == (__IA64_BREAK_KPROBE >> 12)
 893                         || args->err == 0)
 894                         if (pre_kprobes_handler(args))
 895                                 ret = NOTIFY_STOP;
 896                 break;
 897         case DIE_FAULT:
 898                 /* err is vector number from ia64_fault() */
 899                 if (args->err == 36)
 900                         if (post_kprobes_handler(args->regs))
 901                                 ret = NOTIFY_STOP;
 902                 break;
 903         default:
 904                 break;
 905         }
 906         return ret;
 907 }
 908
 909 unsigned long arch_deref_entry_point(void *entry)
 910 {
 911         return ((struct fnptr *)entry)->ip;
 912 }
 913
 914 static struct kprobe trampoline_p = {
 915         .pre_handler = trampoline_probe_handler
 916 };
 917
 918 int __init arch_init_kprobes(void)
 919 {
 920         trampoline_p.addr =
 921                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
 922         return register_kprobe(&trampoline_p);
 923 }
 924
 925 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 926 {
 927         if (p->addr ==
 928                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip)
 929                 return 1;
 930
 931         return 0;
 932 }