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/spinlock.h>
  30 #include <linux/string.h>
  31 #include <linux/slab.h>
  32 #include <linux/preempt.h>
  33 #include <linux/moduleloader.h>
  34
  35 #include <asm/pgtable.h>
  36 #include <asm/kdebug.h>
  37 #include <asm/sections.h>
  38
  39 extern void jprobe_inst_return(void);
  40
  41 /* kprobe_status settings */
  42 #define KPROBE_HIT_ACTIVE       0x00000001
  43 #define KPROBE_HIT_SS           0x00000002
  44
  45 static struct kprobe *current_kprobe, *kprobe_prev;
  46 static unsigned long kprobe_status, kprobe_status_prev;
  47 static struct pt_regs jprobe_saved_regs;
  48
  49 enum instruction_type {A, I, M, F, B, L, X, u};
  50 static enum instruction_type bundle_encoding[32][3] = {
  51   { M, I, I },                          /* 00 */
  52   { M, I, I },                          /* 01 */
  53   { M, I, I },                          /* 02 */
  54   { M, I, I },                          /* 03 */
  55   { M, L, X },                          /* 04 */
  56   { M, L, X },                          /* 05 */
  57   { u, u, u },                          /* 06 */
  58   { u, u, u },                          /* 07 */
  59   { M, M, I },                          /* 08 */
  60   { M, M, I },                          /* 09 */
  61   { M, M, I },                          /* 0A */
  62   { M, M, I },                          /* 0B */
  63   { M, F, I },                          /* 0C */
  64   { M, F, I },                          /* 0D */
  65   { M, M, F },                          /* 0E */
  66   { M, M, F },                          /* 0F */
  67   { M, I, B },                          /* 10 */
  68   { M, I, B },                          /* 11 */
  69   { M, B, B },                          /* 12 */
  70   { M, B, B },                          /* 13 */
  71   { u, u, u },                          /* 14 */
  72   { u, u, u },                          /* 15 */
  73   { B, B, B },                          /* 16 */
  74   { B, B, B },                          /* 17 */
  75   { M, M, B },                          /* 18 */
  76   { M, M, B },                          /* 19 */
  77   { u, u, u },                          /* 1A */
  78   { u, u, u },                          /* 1B */
  79   { M, F, B },                          /* 1C */
  80   { M, F, B },                          /* 1D */
  81   { u, u, u },                          /* 1E */
  82   { u, u, u },                          /* 1F */
  83 };
  84
  85 /*
  86  * In this function we check to see if the instruction
  87  * is IP relative instruction and update the kprobe
  88  * inst flag accordingly
  89  */
  90 static void __kprobes update_kprobe_inst_flag(uint template, uint  slot,
  91                                               uint major_opcode,
  92                                               unsigned long kprobe_inst,
  93                                               struct kprobe *p)
  94 {
  95         p->ainsn.inst_flag = 0;
  96         p->ainsn.target_br_reg = 0;
  97
  98         /* Check for Break instruction
  99          * Bits 37:40 Major opcode to be zero
 100          * Bits 27:32 X6 to be zero
 101          * Bits 32:35 X3 to be zero
 102          */
 103         if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
 104                 /* is a break instruction */
 105                 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
 106                 return;
 107         }
 108
 109         if (bundle_encoding[template][slot] == B) {
 110                 switch (major_opcode) {
 111                   case INDIRECT_CALL_OPCODE:
 112                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 113                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 114                         break;
 115                   case IP_RELATIVE_PREDICT_OPCODE:
 116                   case IP_RELATIVE_BRANCH_OPCODE:
 117                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 118                         break;
 119                   case IP_RELATIVE_CALL_OPCODE:
 120                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 121                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 122                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 123                         break;
 124                 }
 125         } else if (bundle_encoding[template][slot] == X) {
 126                 switch (major_opcode) {
 127                   case LONG_CALL_OPCODE:
 128                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 129                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 130                   break;
 131                 }
 132         }
 133         return;
 134 }
 135
 136 /*
 137  * In this function we check to see if the instruction
 138  * on which we are inserting kprobe is supported.
 139  * Returns 0 if supported
 140  * Returns -EINVAL if unsupported
 141  */
 142 static int __kprobes unsupported_inst(uint template, uint  slot,
 143                                       uint major_opcode,
 144                                       unsigned long kprobe_inst,
 145                                       struct kprobe *p)
 146 {
 147         unsigned long addr = (unsigned long)p->addr;
 148
 149         if (bundle_encoding[template][slot] == I) {
 150                 switch (major_opcode) {
 151                         case 0x0: //I_UNIT_MISC_OPCODE:
 152                         /*
 153                          * Check for Integer speculation instruction
 154                          * - Bit 33-35 to be equal to 0x1
 155                          */
 156                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 157                                 printk(KERN_WARNING
 158                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 159                                         addr);
 160                                 return -EINVAL;
 161                         }
 162
 163                         /*
 164                          * IP relative mov instruction
 165                          *  - Bit 27-35 to be equal to 0x30
 166                          */
 167                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 168                                 printk(KERN_WARNING
 169                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 170                                         addr);
 171                                 return -EINVAL;
 172
 173                         }
 174                 }
 175         }
 176         return 0;
 177 }
 178
 179
 180 /*
 181  * In this function we check to see if the instruction
 182  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 183  * on which we are inserting kprobe is cmp instruction
 184  * with ctype as unc.
 185  */
 186 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
 187                                             uint major_opcode,
 188                                             unsigned long kprobe_inst)
 189 {
 190         cmp_inst_t cmp_inst;
 191         uint ctype_unc = 0;
 192
 193         if (!((bundle_encoding[template][slot] == I) ||
 194                 (bundle_encoding[template][slot] == M)))
 195                 goto out;
 196
 197         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 198                 (major_opcode == 0xE)))
 199                 goto out;
 200
 201         cmp_inst.l = kprobe_inst;
 202         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 203                 /* Integere compare - Register Register (A6 type)*/
 204                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 205                                 &&(cmp_inst.f.c == 1))
 206                         ctype_unc = 1;
 207         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 208                 /* Integere compare - Immediate Register (A8 type)*/
 209                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 210                         ctype_unc = 1;
 211         }
 212 out:
 213         return ctype_unc;
 214 }
 215
 216 /*
 217  * In this function we override the bundle with
 218  * the break instruction at the given slot.
 219  */
 220 static void __kprobes prepare_break_inst(uint template, uint  slot,
 221                                          uint major_opcode,
 222                                          unsigned long kprobe_inst,
 223                                          struct kprobe *p)
 224 {
 225         unsigned long break_inst = BREAK_INST;
 226         bundle_t *bundle = &p->ainsn.insn.bundle;
 227
 228         /*
 229          * Copy the original kprobe_inst qualifying predicate(qp)
 230          * to the break instruction iff !is_cmp_ctype_unc_inst
 231          * because for cmp instruction with ctype equal to unc,
 232          * which is a special instruction always needs to be
 233          * executed regradless of qp
 234          */
 235         if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
 236                 break_inst |= (0x3f & kprobe_inst);
 237
 238         switch (slot) {
 239           case 0:
 240                 bundle->quad0.slot0 = break_inst;
 241                 break;
 242           case 1:
 243                 bundle->quad0.slot1_p0 = break_inst;
 244                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 245                 break;
 246           case 2:
 247                 bundle->quad1.slot2 = break_inst;
 248                 break;
 249         }
 250
 251         /*
 252          * Update the instruction flag, so that we can
 253          * emulate the instruction properly after we
 254          * single step on original instruction
 255          */
 256         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 257 }
 258
 259 static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
 260                 unsigned long *kprobe_inst, uint *major_opcode)
 261 {
 262         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 263         unsigned int template;
 264
 265         template = bundle->quad0.template;
 266
 267         switch (slot) {
 268           case 0:
 269                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 270                 *kprobe_inst = bundle->quad0.slot0;
 271                 break;
 272           case 1:
 273                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 274                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 275                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 276                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 277                 break;
 278           case 2:
 279                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 280                 *kprobe_inst = bundle->quad1.slot2;
 281                 break;
 282         }
 283 }
 284
 285 /* Returns non-zero if the addr is in the Interrupt Vector Table */
 286 static inline int in_ivt_functions(unsigned long addr)
 287 {
 288         return (addr >= (unsigned long)__start_ivt_text
 289                 && addr < (unsigned long)__end_ivt_text);
 290 }
 291
 292 static int __kprobes valid_kprobe_addr(int template, int slot,
 293                                        unsigned long addr)
 294 {
 295         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 296                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
 297                                 "at 0x%lx\n", addr);
 298                 return -EINVAL;
 299         }
 300
 301         if (in_ivt_functions(addr)) {
 302                 printk(KERN_WARNING "Kprobes can't be inserted inside "
 303                                 "IVT functions at 0x%lx\n", addr);
 304                 return -EINVAL;
 305         }
 306
 307         if (slot == 1 && bundle_encoding[template][1] != L) {
 308                 printk(KERN_WARNING "Inserting kprobes on slot #1 "
 309                        "is not supported\n");
 310                 return -EINVAL;
 311         }
 312
 313         return 0;
 314 }
 315
 316 static inline void save_previous_kprobe(void)
 317 {
 318         kprobe_prev = current_kprobe;
 319         kprobe_status_prev = kprobe_status;
 320 }
 321
 322 static inline void restore_previous_kprobe(void)
 323 {
 324         current_kprobe = kprobe_prev;
 325         kprobe_status = kprobe_status_prev;
 326 }
 327
 328 static inline void set_current_kprobe(struct kprobe *p)
 329 {
 330         current_kprobe = p;
 331 }
 332
 333 static void kretprobe_trampoline(void)
 334 {
 335 }
 336
 337 /*
 338  * At this point the target function has been tricked into
 339  * returning into our trampoline.  Lookup the associated instance
 340  * and then:
 341  *    - call the handler function
 342  *    - cleanup by marking the instance as unused
 343  *    - long jump back to the original return address
 344  */
 345 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 346 {
 347         struct kretprobe_instance *ri = NULL;
 348         struct hlist_head *head;
 349         struct hlist_node *node, *tmp;
 350         unsigned long orig_ret_address = 0;
 351         unsigned long trampoline_address =
 352                 ((struct fnptr *)kretprobe_trampoline)->ip;
 353
 354         head = kretprobe_inst_table_head(current);
 355
 356         /*
 357          * It is possible to have multiple instances associated with a given
 358          * task either because an multiple functions in the call path
 359          * have a return probe installed on them, and/or more then one return
 360          * return probe was registered for a target function.
 361          *
 362          * We can handle this because:
 363          *     - instances are always inserted at the head of the list
 364          *     - when multiple return probes are registered for the same
 365          *       function, the first instance's ret_addr will point to the
 366          *       real return address, and all the rest will point to
 367          *       kretprobe_trampoline
 368          */
 369         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 370                 if (ri->task != current)
 371                         /* another task is sharing our hash bucket */
 372                         continue;
 373
 374                 if (ri->rp && ri->rp->handler)
 375                         ri->rp->handler(ri, regs);
 376
 377                 orig_ret_address = (unsigned long)ri->ret_addr;
 378                 recycle_rp_inst(ri);
 379
 380                 if (orig_ret_address != trampoline_address)
 381                         /*
 382                          * This is the real return address. Any other
 383                          * instances associated with this task are for
 384                          * other calls deeper on the call stack
 385                          */
 386                         break;
 387         }
 388
 389         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 390         regs->cr_iip = orig_ret_address;
 391
 392         unlock_kprobes();
 393         preempt_enable_no_resched();
 394
 395         /*
 396          * By returning a non-zero value, we are telling
 397          * kprobe_handler() that we have handled unlocking
 398          * and re-enabling preemption.
 399          */
 400         return 1;
 401 }
 402
 403 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
 404                                       struct pt_regs *regs)
 405 {
 406         struct kretprobe_instance *ri;
 407
 408         if ((ri = get_free_rp_inst(rp)) != NULL) {
 409                 ri->rp = rp;
 410                 ri->task = current;
 411                 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 412
 413                 /* Replace the return addr with trampoline addr */
 414                 regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 415
 416                 add_rp_inst(ri);
 417         } else {
 418                 rp->nmissed++;
 419         }
 420 }
 421
 422 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 423 {
 424         unsigned long addr = (unsigned long) p->addr;
 425         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 426         unsigned long kprobe_inst=0;
 427         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 428         bundle_t *bundle = &p->ainsn.insn.bundle;
 429
 430         memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
 431         memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));
 432
 433         template = bundle->quad0.template;
 434
 435         if(valid_kprobe_addr(template, slot, addr))
 436                 return -EINVAL;
 437
 438         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 439         if (slot == 1 && bundle_encoding[template][1] == L)
 440                 slot++;
 441
 442         /* Get kprobe_inst and major_opcode from the bundle */
 443         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 444
 445         if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
 446                         return -EINVAL;
 447
 448         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
 449
 450         return 0;
 451 }
 452
 453 void __kprobes arch_arm_kprobe(struct kprobe *p)
 454 {
 455         unsigned long addr = (unsigned long)p->addr;
 456         unsigned long arm_addr = addr & ~0xFULL;
 457
 458         memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
 459         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 460 }
 461
 462 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 463 {
 464         unsigned long addr = (unsigned long)p->addr;
 465         unsigned long arm_addr = addr & ~0xFULL;
 466
 467         /* p->opcode contains the original unaltered bundle */
 468         memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
 469         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 470 }
 471
 472 void __kprobes arch_remove_kprobe(struct kprobe *p)
 473 {
 474 }
 475
 476 /*
 477  * We are resuming execution after a single step fault, so the pt_regs
 478  * structure reflects the register state after we executed the instruction
 479  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 480  * the ip to point back to the original stack address. To set the IP address
 481  * to original stack address, handle the case where we need to fixup the
 482  * relative IP address and/or fixup branch register.
 483  */
 484 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 485 {
 486         unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
 487         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 488         unsigned long template;
 489         int slot = ((unsigned long)p->addr & 0xf);
 490
 491         template = p->opcode.bundle.quad0.template;
 492
 493         if (slot == 1 && bundle_encoding[template][1] == L)
 494                 slot = 2;
 495
 496         if (p->ainsn.inst_flag) {
 497
 498                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 499                         /* Fix relative IP address */
 500                         regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
 501                 }
 502
 503                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 504                 /*
 505                  * Fix target branch register, software convention is
 506                  * to use either b0 or b6 or b7, so just checking
 507                  * only those registers
 508                  */
 509                         switch (p->ainsn.target_br_reg) {
 510                         case 0:
 511                                 if ((regs->b0 == bundle_addr) ||
 512                                         (regs->b0 == bundle_addr + 0x10)) {
 513                                         regs->b0 = (regs->b0 - bundle_addr) +
 514                                                 resume_addr;
 515                                 }
 516                                 break;
 517                         case 6:
 518                                 if ((regs->b6 == bundle_addr) ||
 519                                         (regs->b6 == bundle_addr + 0x10)) {
 520                                         regs->b6 = (regs->b6 - bundle_addr) +
 521                                                 resume_addr;
 522                                 }
 523                                 break;
 524                         case 7:
 525                                 if ((regs->b7 == bundle_addr) ||
 526                                         (regs->b7 == bundle_addr + 0x10)) {
 527                                         regs->b7 = (regs->b7 - bundle_addr) +
 528                                                 resume_addr;
 529                                 }
 530                                 break;
 531                         } /* end switch */
 532                 }
 533                 goto turn_ss_off;
 534         }
 535
 536         if (slot == 2) {
 537                 if (regs->cr_iip == bundle_addr + 0x10) {
 538                         regs->cr_iip = resume_addr + 0x10;
 539                 }
 540         } else {
 541                 if (regs->cr_iip == bundle_addr) {
 542                         regs->cr_iip = resume_addr;
 543                 }
 544         }
 545
 546 turn_ss_off:
 547         /* Turn off Single Step bit */
 548         ia64_psr(regs)->ss = 0;
 549 }
 550
 551 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
 552 {
 553         unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
 554         unsigned long slot = (unsigned long)p->addr & 0xf;
 555
 556         /* single step inline if break instruction */
 557         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
 558                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
 559         else
 560                 regs->cr_iip = bundle_addr & ~0xFULL;
 561
 562         if (slot > 2)
 563                 slot = 0;
 564
 565         ia64_psr(regs)->ri = slot;
 566
 567         /* turn on single stepping */
 568         ia64_psr(regs)->ss = 1;
 569 }
 570
 571 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
 572 {
 573         unsigned int slot = ia64_psr(regs)->ri;
 574         unsigned int template, major_opcode;
 575         unsigned long kprobe_inst;
 576         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
 577         bundle_t bundle;
 578
 579         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
 580         template = bundle.quad0.template;
 581
 582         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 583         if (slot == 1 && bundle_encoding[template][1] == L)
 584                 slot++;
 585
 586         /* Get Kprobe probe instruction at given slot*/
 587         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
 588
 589         /* For break instruction,
 590          * Bits 37:40 Major opcode to be zero
 591          * Bits 27:32 X6 to be zero
 592          * Bits 32:35 X3 to be zero
 593          */
 594         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
 595                 /* Not a break instruction */
 596                 return 0;
 597         }
 598
 599         /* Is a break instruction */
 600         return 1;
 601 }
 602
 603 static int __kprobes pre_kprobes_handler(struct die_args *args)
 604 {
 605         struct kprobe *p;
 606         int ret = 0;
 607         struct pt_regs *regs = args->regs;
 608         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 609
 610         preempt_disable();
 611
 612         /* Handle recursion cases */
 613         if (kprobe_running()) {
 614                 p = get_kprobe(addr);
 615                 if (p) {
 616                         if ( (kprobe_status == KPROBE_HIT_SS) &&
 617                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
 618                                 ia64_psr(regs)->ss = 0;
 619                                 unlock_kprobes();
 620                                 goto no_kprobe;
 621                         }
 622                         /* We have reentered the pre_kprobe_handler(), since
 623                          * another probe was hit while within the handler.
 624                          * We here save the original kprobes variables and
 625                          * just single step on the instruction of the new probe
 626                          * without calling any user handlers.
 627                          */
 628                         save_previous_kprobe();
 629                         set_current_kprobe(p);
 630                         p->nmissed++;
 631                         prepare_ss(p, regs);
 632                         kprobe_status = KPROBE_REENTER;
 633                         return 1;
 634                 } else if (args->err == __IA64_BREAK_JPROBE) {
 635                         /*
 636                          * jprobe instrumented function just completed
 637                          */
 638                         p = current_kprobe;
 639                         if (p->break_handler && p->break_handler(p, regs)) {
 640                                 goto ss_probe;
 641                         }
 642                 } else {
 643                         /* Not our break */
 644                         goto no_kprobe;
 645                 }
 646         }
 647
 648         lock_kprobes();
 649         p = get_kprobe(addr);
 650         if (!p) {
 651                 unlock_kprobes();
 652                 if (!is_ia64_break_inst(regs)) {
 653                         /*
 654                          * The breakpoint instruction was removed right
 655                          * after we hit it.  Another cpu has removed
 656                          * either a probepoint or a debugger breakpoint
 657                          * at this address.  In either case, no further
 658                          * handling of this interrupt is appropriate.
 659                          */
 660                         ret = 1;
 661
 662                 }
 663
 664                 /* Not one of our break, let kernel handle it */
 665                 goto no_kprobe;
 666         }
 667
 668         kprobe_status = KPROBE_HIT_ACTIVE;
 669         set_current_kprobe(p);
 670
 671         if (p->pre_handler && p->pre_handler(p, regs))
 672                 /*
 673                  * Our pre-handler is specifically requesting that we just
 674                  * do a return.  This is used for both the jprobe pre-handler
 675                  * and the kretprobe trampoline
 676                  */
 677                 return 1;
 678
 679 ss_probe:
 680         prepare_ss(p, regs);
 681         kprobe_status = KPROBE_HIT_SS;
 682         return 1;
 683
 684 no_kprobe:
 685         preempt_enable_no_resched();
 686         return ret;
 687 }
 688
 689 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
 690 {
 691         if (!kprobe_running())
 692                 return 0;
 693
 694         if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
 695                 kprobe_status = KPROBE_HIT_SSDONE;
 696                 current_kprobe->post_handler(current_kprobe, regs, 0);
 697         }
 698
 699         resume_execution(current_kprobe, regs);
 700
 701         /*Restore back the original saved kprobes variables and continue. */
 702         if (kprobe_status == KPROBE_REENTER) {
 703                 restore_previous_kprobe();
 704                 goto out;
 705         }
 706
 707         unlock_kprobes();
 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         if (!kprobe_running())
 717                 return 0;
 718
 719         if (current_kprobe->fault_handler &&
 720             current_kprobe->fault_handler(current_kprobe, regs, trapnr))
 721                 return 1;
 722
 723         if (kprobe_status & KPROBE_HIT_SS) {
 724                 resume_execution(current_kprobe, regs);
 725                 unlock_kprobes();
 726                 preempt_enable_no_resched();
 727         }
 728
 729         return 0;
 730 }
 731
 732 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 733                                        unsigned long val, void *data)
 734 {
 735         struct die_args *args = (struct die_args *)data;
 736         switch(val) {
 737         case DIE_BREAK:
 738                 if (pre_kprobes_handler(args))
 739                         return NOTIFY_STOP;
 740                 break;
 741         case DIE_SS:
 742                 if (post_kprobes_handler(args->regs))
 743                         return NOTIFY_STOP;
 744                 break;
 745         case DIE_PAGE_FAULT:
 746                 if (kprobes_fault_handler(args->regs, args->trapnr))
 747                         return NOTIFY_STOP;
 748         default:
 749                 break;
 750         }
 751         return NOTIFY_DONE;
 752 }
 753
 754 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 755 {
 756         struct jprobe *jp = container_of(p, struct jprobe, kp);
 757         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 758
 759         /* save architectural state */
 760         jprobe_saved_regs = *regs;
 761
 762         /* after rfi, execute the jprobe instrumented function */
 763         regs->cr_iip = addr & ~0xFULL;
 764         ia64_psr(regs)->ri = addr & 0xf;
 765         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 766
 767         /*
 768          * fix the return address to our jprobe_inst_return() function
 769          * in the jprobes.S file
 770          */
 771         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 772
 773         return 1;
 774 }
 775
 776 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 777 {
 778         *regs = jprobe_saved_regs;
 779         return 1;
 780 }
 781
 782 static struct kprobe trampoline_p = {
 783         .pre_handler = trampoline_probe_handler
 784 };
 785
 786 int __init arch_init_kprobes(void)
 787 {
 788         trampoline_p.addr =
 789                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
 790         return register_kprobe(&trampoline_p);
 791 }