arch/ia64/kernel/kprobes.c

   1 /*
   2  *  Kernel Probes (KProbes)
   3  *  arch/ia64/kernel/kprobes.c
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  *
  19  * Copyright (C) IBM Corporation, 2002, 2004
  20  * Copyright (C) Intel Corporation, 2005
  21  *
  22  * 2005-Apr     Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
  23  *              <anil.s.keshavamurthy@intel.com> adapted from i386
  24  */
  25
  26 #include <linux/config.h>
  27 #include <linux/kprobes.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/string.h>
  30 #include <linux/slab.h>
  31 #include <linux/preempt.h>
  32 #include <linux/moduleloader.h>
  33
  34 #include <asm/pgtable.h>
  35 #include <asm/kdebug.h>
  36 #include <asm/sections.h>
  37
  38 extern void jprobe_inst_return(void);
  39
  40 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
  41 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
  42
  43 enum instruction_type {A, I, M, F, B, L, X, u};
  44 static enum instruction_type bundle_encoding[32][3] = {
  45   { M, I, I },                          /* 00 */
  46   { M, I, I },                          /* 01 */
  47   { M, I, I },                          /* 02 */
  48   { M, I, I },                          /* 03 */
  49   { M, L, X },                          /* 04 */
  50   { M, L, X },                          /* 05 */
  51   { u, u, u },                          /* 06 */
  52   { u, u, u },                          /* 07 */
  53   { M, M, I },                          /* 08 */
  54   { M, M, I },                          /* 09 */
  55   { M, M, I },                          /* 0A */
  56   { M, M, I },                          /* 0B */
  57   { M, F, I },                          /* 0C */
  58   { M, F, I },                          /* 0D */
  59   { M, M, F },                          /* 0E */
  60   { M, M, F },                          /* 0F */
  61   { M, I, B },                          /* 10 */
  62   { M, I, B },                          /* 11 */
  63   { M, B, B },                          /* 12 */
  64   { M, B, B },                          /* 13 */
  65   { u, u, u },                          /* 14 */
  66   { u, u, u },                          /* 15 */
  67   { B, B, B },                          /* 16 */
  68   { B, B, B },                          /* 17 */
  69   { M, M, B },                          /* 18 */
  70   { M, M, B },                          /* 19 */
  71   { u, u, u },                          /* 1A */
  72   { u, u, u },                          /* 1B */
  73   { M, F, B },                          /* 1C */
  74   { M, F, B },                          /* 1D */
  75   { u, u, u },                          /* 1E */
  76   { u, u, u },                          /* 1F */
  77 };
  78
  79 /*
  80  * In this function we check to see if the instruction
  81  * is IP relative instruction and update the kprobe
  82  * inst flag accordingly
  83  */
  84 static void __kprobes update_kprobe_inst_flag(uint template, uint  slot,
  85                                               uint major_opcode,
  86                                               unsigned long kprobe_inst,
  87                                               struct kprobe *p)
  88 {
  89         p->ainsn.inst_flag = 0;
  90         p->ainsn.target_br_reg = 0;
  91
  92         /* Check for Break instruction
  93          * Bits 37:40 Major opcode to be zero
  94          * Bits 27:32 X6 to be zero
  95          * Bits 32:35 X3 to be zero
  96          */
  97         if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
  98                 /* is a break instruction */
  99                 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
 100                 return;
 101         }
 102
 103         if (bundle_encoding[template][slot] == B) {
 104                 switch (major_opcode) {
 105                   case INDIRECT_CALL_OPCODE:
 106                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 107                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 108                         break;
 109                   case IP_RELATIVE_PREDICT_OPCODE:
 110                   case IP_RELATIVE_BRANCH_OPCODE:
 111                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 112                         break;
 113                   case IP_RELATIVE_CALL_OPCODE:
 114                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 115                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 116                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 117                         break;
 118                 }
 119         } else if (bundle_encoding[template][slot] == X) {
 120                 switch (major_opcode) {
 121                   case LONG_CALL_OPCODE:
 122                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 123                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 124                   break;
 125                 }
 126         }
 127         return;
 128 }
 129
 130 /*
 131  * In this function we check to see if the instruction
 132  * on which we are inserting kprobe is supported.
 133  * Returns 0 if supported
 134  * Returns -EINVAL if unsupported
 135  */
 136 static int __kprobes unsupported_inst(uint template, uint  slot,
 137                                       uint major_opcode,
 138                                       unsigned long kprobe_inst,
 139                                       struct kprobe *p)
 140 {
 141         unsigned long addr = (unsigned long)p->addr;
 142
 143         if (bundle_encoding[template][slot] == I) {
 144                 switch (major_opcode) {
 145                         case 0x0: //I_UNIT_MISC_OPCODE:
 146                         /*
 147                          * Check for Integer speculation instruction
 148                          * - Bit 33-35 to be equal to 0x1
 149                          */
 150                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 151                                 printk(KERN_WARNING
 152                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 153                                         addr);
 154                                 return -EINVAL;
 155                         }
 156
 157                         /*
 158                          * IP relative mov instruction
 159                          *  - Bit 27-35 to be equal to 0x30
 160                          */
 161                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 162                                 printk(KERN_WARNING
 163                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 164                                         addr);
 165                                 return -EINVAL;
 166
 167                         }
 168                 }
 169         }
 170         return 0;
 171 }
 172
 173
 174 /*
 175  * In this function we check to see if the instruction
 176  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 177  * on which we are inserting kprobe is cmp instruction
 178  * with ctype as unc.
 179  */
 180 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
 181                                             uint major_opcode,
 182                                             unsigned long kprobe_inst)
 183 {
 184         cmp_inst_t cmp_inst;
 185         uint ctype_unc = 0;
 186
 187         if (!((bundle_encoding[template][slot] == I) ||
 188                 (bundle_encoding[template][slot] == M)))
 189                 goto out;
 190
 191         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 192                 (major_opcode == 0xE)))
 193                 goto out;
 194
 195         cmp_inst.l = kprobe_inst;
 196         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 197                 /* Integere compare - Register Register (A6 type)*/
 198                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 199                                 &&(cmp_inst.f.c == 1))
 200                         ctype_unc = 1;
 201         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 202                 /* Integere compare - Immediate Register (A8 type)*/
 203                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 204                         ctype_unc = 1;
 205         }
 206 out:
 207         return ctype_unc;
 208 }
 209
 210 /*
 211  * In this function we override the bundle with
 212  * the break instruction at the given slot.
 213  */
 214 static void __kprobes prepare_break_inst(uint template, uint  slot,
 215                                          uint major_opcode,
 216                                          unsigned long kprobe_inst,
 217                                          struct kprobe *p)
 218 {
 219         unsigned long break_inst = BREAK_INST;
 220         bundle_t *bundle = &p->ainsn.insn.bundle;
 221
 222         /*
 223          * Copy the original kprobe_inst qualifying predicate(qp)
 224          * to the break instruction iff !is_cmp_ctype_unc_inst
 225          * because for cmp instruction with ctype equal to unc,
 226          * which is a special instruction always needs to be
 227          * executed regradless of qp
 228          */
 229         if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
 230                 break_inst |= (0x3f & kprobe_inst);
 231
 232         switch (slot) {
 233           case 0:
 234                 bundle->quad0.slot0 = break_inst;
 235                 break;
 236           case 1:
 237                 bundle->quad0.slot1_p0 = break_inst;
 238                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 239                 break;
 240           case 2:
 241                 bundle->quad1.slot2 = break_inst;
 242                 break;
 243         }
 244
 245         /*
 246          * Update the instruction flag, so that we can
 247          * emulate the instruction properly after we
 248          * single step on original instruction
 249          */
 250         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 251 }
 252
 253 static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
 254                 unsigned long *kprobe_inst, uint *major_opcode)
 255 {
 256         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 257         unsigned int template;
 258
 259         template = bundle->quad0.template;
 260
 261         switch (slot) {
 262           case 0:
 263                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 264                 *kprobe_inst = bundle->quad0.slot0;
 265                 break;
 266           case 1:
 267                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 268                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 269                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 270                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 271                 break;
 272           case 2:
 273                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 274                 *kprobe_inst = bundle->quad1.slot2;
 275                 break;
 276         }
 277 }
 278
 279 /* Returns non-zero if the addr is in the Interrupt Vector Table */
 280 static inline int in_ivt_functions(unsigned long addr)
 281 {
 282         return (addr >= (unsigned long)__start_ivt_text
 283                 && addr < (unsigned long)__end_ivt_text);
 284 }
 285
 286 static int __kprobes valid_kprobe_addr(int template, int slot,
 287                                        unsigned long addr)
 288 {
 289         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 290                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
 291                                 "at 0x%lx\n", addr);
 292                 return -EINVAL;
 293         }
 294
 295         if (in_ivt_functions(addr)) {
 296                 printk(KERN_WARNING "Kprobes can't be inserted inside "
 297                                 "IVT functions at 0x%lx\n", addr);
 298                 return -EINVAL;
 299         }
 300
 301         if (slot == 1 && bundle_encoding[template][1] != L) {
 302                 printk(KERN_WARNING "Inserting kprobes on slot #1 "
 303                        "is not supported\n");
 304                 return -EINVAL;
 305         }
 306
 307         return 0;
 308 }
 309
 310 static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
 311 {
 312         kcb->prev_kprobe.kp = kprobe_running();
 313         kcb->prev_kprobe.status = kcb->kprobe_status;
 314 }
 315
 316 static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 317 {
 318         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 319         kcb->kprobe_status = kcb->prev_kprobe.status;
 320 }
 321
 322 static inline void set_current_kprobe(struct kprobe *p,
 323                         struct kprobe_ctlblk *kcb)
 324 {
 325         __get_cpu_var(current_kprobe) = p;
 326 }
 327
 328 static void kretprobe_trampoline(void)
 329 {
 330 }
 331
 332 /*
 333  * At this point the target function has been tricked into
 334  * returning into our trampoline.  Lookup the associated instance
 335  * and then:
 336  *    - call the handler function
 337  *    - cleanup by marking the instance as unused
 338  *    - long jump back to the original return address
 339  */
 340 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 341 {
 342         struct kretprobe_instance *ri = NULL;
 343         struct hlist_head *head;
 344         struct hlist_node *node, *tmp;
 345         unsigned long flags, orig_ret_address = 0;
 346         unsigned long trampoline_address =
 347                 ((struct fnptr *)kretprobe_trampoline)->ip;
 348
 349         spin_lock_irqsave(&kretprobe_lock, flags);
 350         head = kretprobe_inst_table_head(current);
 351
 352         /*
 353          * It is possible to have multiple instances associated with a given
 354          * task either because an multiple functions in the call path
 355          * have a return probe installed on them, and/or more then one return
 356          * return probe was registered for a target function.
 357          *
 358          * We can handle this because:
 359          *     - instances are always inserted at the head of the list
 360          *     - when multiple return probes are registered for the same
 361          *       function, the first instance's ret_addr will point to the
 362          *       real return address, and all the rest will point to
 363          *       kretprobe_trampoline
 364          */
 365         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 366                 if (ri->task != current)
 367                         /* another task is sharing our hash bucket */
 368                         continue;
 369
 370                 if (ri->rp && ri->rp->handler)
 371                         ri->rp->handler(ri, regs);
 372
 373                 orig_ret_address = (unsigned long)ri->ret_addr;
 374                 recycle_rp_inst(ri);
 375
 376                 if (orig_ret_address != trampoline_address)
 377                         /*
 378                          * This is the real return address. Any other
 379                          * instances associated with this task are for
 380                          * other calls deeper on the call stack
 381                          */
 382                         break;
 383         }
 384
 385         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 386         regs->cr_iip = orig_ret_address;
 387
 388         reset_current_kprobe();
 389         spin_unlock_irqrestore(&kretprobe_lock, flags);
 390         preempt_enable_no_resched();
 391
 392         /*
 393          * By returning a non-zero value, we are telling
 394          * kprobe_handler() that we have handled unlocking
 395          * and re-enabling preemption
 396          */
 397         return 1;
 398 }
 399
 400 /* Called with kretprobe_lock held */
 401 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
 402                                       struct pt_regs *regs)
 403 {
 404         struct kretprobe_instance *ri;
 405
 406         if ((ri = get_free_rp_inst(rp)) != NULL) {
 407                 ri->rp = rp;
 408                 ri->task = current;
 409                 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 410
 411                 /* Replace the return addr with trampoline addr */
 412                 regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 413
 414                 add_rp_inst(ri);
 415         } else {
 416                 rp->nmissed++;
 417         }
 418 }
 419
 420 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 421 {
 422         unsigned long addr = (unsigned long) p->addr;
 423         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 424         unsigned long kprobe_inst=0;
 425         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 426         bundle_t *bundle = &p->ainsn.insn.bundle;
 427
 428         memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
 429         memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));
 430
 431         template = bundle->quad0.template;
 432
 433         if(valid_kprobe_addr(template, slot, addr))
 434                 return -EINVAL;
 435
 436         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 437         if (slot == 1 && bundle_encoding[template][1] == L)
 438                 slot++;
 439
 440         /* Get kprobe_inst and major_opcode from the bundle */
 441         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 442
 443         if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
 444                         return -EINVAL;
 445
 446         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
 447
 448         return 0;
 449 }
 450
 451 void __kprobes arch_arm_kprobe(struct kprobe *p)
 452 {
 453         unsigned long addr = (unsigned long)p->addr;
 454         unsigned long arm_addr = addr & ~0xFULL;
 455
 456         memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
 457         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 458 }
 459
 460 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 461 {
 462         unsigned long addr = (unsigned long)p->addr;
 463         unsigned long arm_addr = addr & ~0xFULL;
 464
 465         /* p->opcode contains the original unaltered bundle */
 466         memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
 467         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 468 }
 469
 470 void __kprobes arch_remove_kprobe(struct kprobe *p)
 471 {
 472 }
 473
 474 /*
 475  * We are resuming execution after a single step fault, so the pt_regs
 476  * structure reflects the register state after we executed the instruction
 477  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 478  * the ip to point back to the original stack address. To set the IP address
 479  * to original stack address, handle the case where we need to fixup the
 480  * relative IP address and/or fixup branch register.
 481  */
 482 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 483 {
 484         unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
 485         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 486         unsigned long template;
 487         int slot = ((unsigned long)p->addr & 0xf);
 488
 489         template = p->opcode.bundle.quad0.template;
 490
 491         if (slot == 1 && bundle_encoding[template][1] == L)
 492                 slot = 2;
 493
 494         if (p->ainsn.inst_flag) {
 495
 496                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 497                         /* Fix relative IP address */
 498                         regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
 499                 }
 500
 501                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 502                 /*
 503                  * Fix target branch register, software convention is
 504                  * to use either b0 or b6 or b7, so just checking
 505                  * only those registers
 506                  */
 507                         switch (p->ainsn.target_br_reg) {
 508                         case 0:
 509                                 if ((regs->b0 == bundle_addr) ||
 510                                         (regs->b0 == bundle_addr + 0x10)) {
 511                                         regs->b0 = (regs->b0 - bundle_addr) +
 512                                                 resume_addr;
 513                                 }
 514                                 break;
 515                         case 6:
 516                                 if ((regs->b6 == bundle_addr) ||
 517                                         (regs->b6 == bundle_addr + 0x10)) {
 518                                         regs->b6 = (regs->b6 - bundle_addr) +
 519                                                 resume_addr;
 520                                 }
 521                                 break;
 522                         case 7:
 523                                 if ((regs->b7 == bundle_addr) ||
 524                                         (regs->b7 == bundle_addr + 0x10)) {
 525                                         regs->b7 = (regs->b7 - bundle_addr) +
 526                                                 resume_addr;
 527                                 }
 528                                 break;
 529                         } /* end switch */
 530                 }
 531                 goto turn_ss_off;
 532         }
 533
 534         if (slot == 2) {
 535                 if (regs->cr_iip == bundle_addr + 0x10) {
 536                         regs->cr_iip = resume_addr + 0x10;
 537                 }
 538         } else {
 539                 if (regs->cr_iip == bundle_addr) {
 540                         regs->cr_iip = resume_addr;
 541                 }
 542         }
 543
 544 turn_ss_off:
 545         /* Turn off Single Step bit */
 546         ia64_psr(regs)->ss = 0;
 547 }
 548
 549 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
 550 {
 551         unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
 552         unsigned long slot = (unsigned long)p->addr & 0xf;
 553
 554         /* single step inline if break instruction */
 555         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
 556                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
 557         else
 558                 regs->cr_iip = bundle_addr & ~0xFULL;
 559
 560         if (slot > 2)
 561                 slot = 0;
 562
 563         ia64_psr(regs)->ri = slot;
 564
 565         /* turn on single stepping */
 566         ia64_psr(regs)->ss = 1;
 567 }
 568
 569 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
 570 {
 571         unsigned int slot = ia64_psr(regs)->ri;
 572         unsigned int template, major_opcode;
 573         unsigned long kprobe_inst;
 574         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
 575         bundle_t bundle;
 576
 577         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
 578         template = bundle.quad0.template;
 579
 580         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 581         if (slot == 1 && bundle_encoding[template][1] == L)
 582                 slot++;
 583
 584         /* Get Kprobe probe instruction at given slot*/
 585         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
 586
 587         /* For break instruction,
 588          * Bits 37:40 Major opcode to be zero
 589          * Bits 27:32 X6 to be zero
 590          * Bits 32:35 X3 to be zero
 591          */
 592         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
 593                 /* Not a break instruction */
 594                 return 0;
 595         }
 596
 597         /* Is a break instruction */
 598         return 1;
 599 }
 600
 601 static int __kprobes pre_kprobes_handler(struct die_args *args)
 602 {
 603         struct kprobe *p;
 604         int ret = 0;
 605         struct pt_regs *regs = args->regs;
 606         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 607         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 608
 609         /* Handle recursion cases */
 610         if (kprobe_running()) {
 611                 p = get_kprobe(addr);
 612                 if (p) {
 613                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
 614                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
 615                                 ia64_psr(regs)->ss = 0;
 616                                 goto no_kprobe;
 617                         }
 618                         /* We have reentered the pre_kprobe_handler(), since
 619                          * another probe was hit while within the handler.
 620                          * We here save the original kprobes variables and
 621                          * just single step on the instruction of the new probe
 622                          * without calling any user handlers.
 623                          */
 624                         save_previous_kprobe(kcb);
 625                         set_current_kprobe(p, kcb);
 626                         p->nmissed++;
 627                         prepare_ss(p, regs);
 628                         kcb->kprobe_status = KPROBE_REENTER;
 629                         return 1;
 630                 } else if (args->err == __IA64_BREAK_JPROBE) {
 631                         /*
 632                          * jprobe instrumented function just completed
 633                          */
 634                         p = __get_cpu_var(current_kprobe);
 635                         if (p->break_handler && p->break_handler(p, regs)) {
 636                                 goto ss_probe;
 637                         }
 638                 } else {
 639                         /* Not our break */
 640                         goto no_kprobe;
 641                 }
 642         }
 643
 644         p = get_kprobe(addr);
 645         if (!p) {
 646                 if (!is_ia64_break_inst(regs)) {
 647                         /*
 648                          * The breakpoint instruction was removed right
 649                          * after we hit it.  Another cpu has removed
 650                          * either a probepoint or a debugger breakpoint
 651                          * at this address.  In either case, no further
 652                          * handling of this interrupt is appropriate.
 653                          */
 654                         ret = 1;
 655
 656                 }
 657
 658                 /* Not one of our break, let kernel handle it */
 659                 goto no_kprobe;
 660         }
 661
 662         /*
 663          * This preempt_disable() matches the preempt_enable_no_resched()
 664          * in post_kprobes_handler()
 665          */
 666         preempt_disable();
 667         set_current_kprobe(p, kcb);
 668         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 669
 670         if (p->pre_handler && p->pre_handler(p, regs))
 671                 /*
 672                  * Our pre-handler is specifically requesting that we just
 673                  * do a return.  This is used for both the jprobe pre-handler
 674                  * and the kretprobe trampoline
 675                  */
 676                 return 1;
 677
 678 ss_probe:
 679         prepare_ss(p, regs);
 680         kcb->kprobe_status = KPROBE_HIT_SS;
 681         return 1;
 682
 683 no_kprobe:
 684         return ret;
 685 }
 686
 687 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
 688 {
 689         struct kprobe *cur = kprobe_running();
 690         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 691
 692         if (!cur)
 693                 return 0;
 694
 695         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 696                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 697                 cur->post_handler(cur, regs, 0);
 698         }
 699
 700         resume_execution(cur, regs);
 701
 702         /*Restore back the original saved kprobes variables and continue. */
 703         if (kcb->kprobe_status == KPROBE_REENTER) {
 704                 restore_previous_kprobe(kcb);
 705                 goto out;
 706         }
 707         reset_current_kprobe();
 708
 709 out:
 710         preempt_enable_no_resched();
 711         return 1;
 712 }
 713
 714 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 715 {
 716         struct kprobe *cur = kprobe_running();
 717         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 718
 719         if (!cur)
 720                 return 0;
 721
 722         if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 723                 return 1;
 724
 725         if (kcb->kprobe_status & KPROBE_HIT_SS) {
 726                 resume_execution(cur, regs);
 727                 reset_current_kprobe();
 728                 preempt_enable_no_resched();
 729         }
 730
 731         return 0;
 732 }
 733
 734 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 735                                        unsigned long val, void *data)
 736 {
 737         struct die_args *args = (struct die_args *)data;
 738         int ret = NOTIFY_DONE;
 739
 740         rcu_read_lock();
 741         switch(val) {
 742         case DIE_BREAK:
 743                 if (pre_kprobes_handler(args))
 744                         ret = NOTIFY_STOP;
 745                 break;
 746         case DIE_SS:
 747                 if (post_kprobes_handler(args->regs))
 748                         ret = NOTIFY_STOP;
 749                 break;
 750         case DIE_PAGE_FAULT:
 751                 if (kprobes_fault_handler(args->regs, args->trapnr))
 752                         ret = NOTIFY_STOP;
 753         default:
 754                 break;
 755         }
 756         rcu_read_unlock();
 757         return ret;
 758 }
 759
 760 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 761 {
 762         struct jprobe *jp = container_of(p, struct jprobe, kp);
 763         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 764         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 765
 766         /* save architectural state */
 767         kcb->jprobe_saved_regs = *regs;
 768
 769         /* after rfi, execute the jprobe instrumented function */
 770         regs->cr_iip = addr & ~0xFULL;
 771         ia64_psr(regs)->ri = addr & 0xf;
 772         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 773
 774         /*
 775          * fix the return address to our jprobe_inst_return() function
 776          * in the jprobes.S file
 777          */
 778         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 779
 780         return 1;
 781 }
 782
 783 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 784 {
 785         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 786
 787         *regs = kcb->jprobe_saved_regs;
 788         return 1;
 789 }
 790
 791 static struct kprobe trampoline_p = {
 792         .pre_handler = trampoline_probe_handler
 793 };
 794
 795 int __init arch_init_kprobes(void)
 796 {
 797         trampoline_p.addr =
 798                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
 799         return register_kprobe(&trampoline_p);
 800 }