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 update_kprobe_inst_flag(uint template, uint  slot, uint major_opcode,
  91         unsigned long kprobe_inst, struct kprobe *p)
  92 {
  93         p->ainsn.inst_flag = 0;
  94         p->ainsn.target_br_reg = 0;
  95
  96         if (bundle_encoding[template][slot] == B) {
  97                 switch (major_opcode) {
  98                   case INDIRECT_CALL_OPCODE:
  99                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 100                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 101                         break;
 102                   case IP_RELATIVE_PREDICT_OPCODE:
 103                   case IP_RELATIVE_BRANCH_OPCODE:
 104                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 105                         break;
 106                   case IP_RELATIVE_CALL_OPCODE:
 107                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 108                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 109                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 110                         break;
 111                 }
 112         } else if (bundle_encoding[template][slot] == X) {
 113                 switch (major_opcode) {
 114                   case LONG_CALL_OPCODE:
 115                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 116                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 117                   break;
 118                 }
 119         }
 120         return;
 121 }
 122
 123 /*
 124  * In this function we check to see if the instruction
 125  * on which we are inserting kprobe is supported.
 126  * Returns 0 if supported
 127  * Returns -EINVAL if unsupported
 128  */
 129 static int unsupported_inst(uint template, uint  slot, uint major_opcode,
 130         unsigned long kprobe_inst, struct kprobe *p)
 131 {
 132         unsigned long addr = (unsigned long)p->addr;
 133
 134         if (bundle_encoding[template][slot] == I) {
 135                 switch (major_opcode) {
 136                         case 0x0: //I_UNIT_MISC_OPCODE:
 137                         /*
 138                          * Check for Integer speculation instruction
 139                          * - Bit 33-35 to be equal to 0x1
 140                          */
 141                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 142                                 printk(KERN_WARNING
 143                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 144                                         addr);
 145                                 return -EINVAL;
 146                         }
 147
 148                         /*
 149                          * IP relative mov instruction
 150                          *  - Bit 27-35 to be equal to 0x30
 151                          */
 152                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 153                                 printk(KERN_WARNING
 154                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 155                                         addr);
 156                                 return -EINVAL;
 157
 158                         }
 159                 }
 160         }
 161         return 0;
 162 }
 163
 164
 165 /*
 166  * In this function we check to see if the instruction
 167  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 168  * on which we are inserting kprobe is cmp instruction
 169  * with ctype as unc.
 170  */
 171 static uint is_cmp_ctype_unc_inst(uint template, uint slot, uint major_opcode,
 172 unsigned long kprobe_inst)
 173 {
 174         cmp_inst_t cmp_inst;
 175         uint ctype_unc = 0;
 176
 177         if (!((bundle_encoding[template][slot] == I) ||
 178                 (bundle_encoding[template][slot] == M)))
 179                 goto out;
 180
 181         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 182                 (major_opcode == 0xE)))
 183                 goto out;
 184
 185         cmp_inst.l = kprobe_inst;
 186         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 187                 /* Integere compare - Register Register (A6 type)*/
 188                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 189                                 &&(cmp_inst.f.c == 1))
 190                         ctype_unc = 1;
 191         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 192                 /* Integere compare - Immediate Register (A8 type)*/
 193                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 194                         ctype_unc = 1;
 195         }
 196 out:
 197         return ctype_unc;
 198 }
 199
 200 /*
 201  * In this function we override the bundle with
 202  * the break instruction at the given slot.
 203  */
 204 static void prepare_break_inst(uint template, uint  slot, uint major_opcode,
 205         unsigned long kprobe_inst, struct kprobe *p)
 206 {
 207         unsigned long break_inst = BREAK_INST;
 208         bundle_t *bundle = &p->ainsn.insn.bundle;
 209
 210         /*
 211          * Copy the original kprobe_inst qualifying predicate(qp)
 212          * to the break instruction iff !is_cmp_ctype_unc_inst
 213          * because for cmp instruction with ctype equal to unc,
 214          * which is a special instruction always needs to be
 215          * executed regradless of qp
 216          */
 217         if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
 218                 break_inst |= (0x3f & kprobe_inst);
 219
 220         switch (slot) {
 221           case 0:
 222                 bundle->quad0.slot0 = break_inst;
 223                 break;
 224           case 1:
 225                 bundle->quad0.slot1_p0 = break_inst;
 226                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 227                 break;
 228           case 2:
 229                 bundle->quad1.slot2 = break_inst;
 230                 break;
 231         }
 232
 233         /*
 234          * Update the instruction flag, so that we can
 235          * emulate the instruction properly after we
 236          * single step on original instruction
 237          */
 238         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 239 }
 240
 241 static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
 242                 unsigned long *kprobe_inst, uint *major_opcode)
 243 {
 244         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 245         unsigned int template;
 246
 247         template = bundle->quad0.template;
 248
 249         switch (slot) {
 250           case 0:
 251                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 252                 *kprobe_inst = bundle->quad0.slot0;
 253                 break;
 254           case 1:
 255                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 256                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 257                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 258                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 259                 break;
 260           case 2:
 261                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 262                 *kprobe_inst = bundle->quad1.slot2;
 263                 break;
 264         }
 265 }
 266
 267 /* Returns non-zero if the addr is in the Interrupt Vector Table */
 268 static inline int in_ivt_functions(unsigned long addr)
 269 {
 270         return (addr >= (unsigned long)__start_ivt_text
 271                 && addr < (unsigned long)__end_ivt_text);
 272 }
 273
 274 static int valid_kprobe_addr(int template, int slot, unsigned long addr)
 275 {
 276         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 277                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
 278                                 "at 0x%lx\n", addr);
 279                 return -EINVAL;
 280         }
 281
 282         if (in_ivt_functions(addr)) {
 283                 printk(KERN_WARNING "Kprobes can't be inserted inside "
 284                                 "IVT functions at 0x%lx\n", addr);
 285                 return -EINVAL;
 286         }
 287
 288         if (slot == 1 && bundle_encoding[template][1] != L) {
 289                 printk(KERN_WARNING "Inserting kprobes on slot #1 "
 290                        "is not supported\n");
 291                 return -EINVAL;
 292         }
 293
 294         return 0;
 295 }
 296
 297 static inline void save_previous_kprobe(void)
 298 {
 299         kprobe_prev = current_kprobe;
 300         kprobe_status_prev = kprobe_status;
 301 }
 302
 303 static inline void restore_previous_kprobe(void)
 304 {
 305         current_kprobe = kprobe_prev;
 306         kprobe_status = kprobe_status_prev;
 307 }
 308
 309 static inline void set_current_kprobe(struct kprobe *p)
 310 {
 311         current_kprobe = p;
 312 }
 313
 314 static void kretprobe_trampoline(void)
 315 {
 316 }
 317
 318 /*
 319  * At this point the target function has been tricked into
 320  * returning into our trampoline.  Lookup the associated instance
 321  * and then:
 322  *    - call the handler function
 323  *    - cleanup by marking the instance as unused
 324  *    - long jump back to the original return address
 325  */
 326 int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 327 {
 328         struct kretprobe_instance *ri = NULL;
 329         struct hlist_head *head;
 330         struct hlist_node *node, *tmp;
 331         unsigned long orig_ret_address = 0;
 332         unsigned long trampoline_address =
 333                 ((struct fnptr *)kretprobe_trampoline)->ip;
 334
 335         head = kretprobe_inst_table_head(current);
 336
 337         /*
 338          * It is possible to have multiple instances associated with a given
 339          * task either because an multiple functions in the call path
 340          * have a return probe installed on them, and/or more then one return
 341          * return probe was registered for a target function.
 342          *
 343          * We can handle this because:
 344          *     - instances are always inserted at the head of the list
 345          *     - when multiple return probes are registered for the same
 346          *       function, the first instance's ret_addr will point to the
 347          *       real return address, and all the rest will point to
 348          *       kretprobe_trampoline
 349          */
 350         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 351                 if (ri->task != current)
 352                         /* another task is sharing our hash bucket */
 353                         continue;
 354
 355                 if (ri->rp && ri->rp->handler)
 356                         ri->rp->handler(ri, regs);
 357
 358                 orig_ret_address = (unsigned long)ri->ret_addr;
 359                 recycle_rp_inst(ri);
 360
 361                 if (orig_ret_address != trampoline_address)
 362                         /*
 363                          * This is the real return address. Any other
 364                          * instances associated with this task are for
 365                          * other calls deeper on the call stack
 366                          */
 367                         break;
 368         }
 369
 370         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 371         regs->cr_iip = orig_ret_address;
 372
 373         unlock_kprobes();
 374         preempt_enable_no_resched();
 375
 376         /*
 377          * By returning a non-zero value, we are telling
 378          * kprobe_handler() that we have handled unlocking
 379          * and re-enabling preemption.
 380          */
 381         return 1;
 382 }
 383
 384 void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs)
 385 {
 386         struct kretprobe_instance *ri;
 387
 388         if ((ri = get_free_rp_inst(rp)) != NULL) {
 389                 ri->rp = rp;
 390                 ri->task = current;
 391                 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 392
 393                 /* Replace the return addr with trampoline addr */
 394                 regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 395
 396                 add_rp_inst(ri);
 397         } else {
 398                 rp->nmissed++;
 399         }
 400 }
 401
 402 int arch_prepare_kprobe(struct kprobe *p)
 403 {
 404         unsigned long addr = (unsigned long) p->addr;
 405         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 406         unsigned long kprobe_inst=0;
 407         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 408         bundle_t *bundle = &p->ainsn.insn.bundle;
 409
 410         memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
 411         memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));
 412
 413         template = bundle->quad0.template;
 414
 415         if(valid_kprobe_addr(template, slot, addr))
 416                 return -EINVAL;
 417
 418         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 419         if (slot == 1 && bundle_encoding[template][1] == L)
 420                 slot++;
 421
 422         /* Get kprobe_inst and major_opcode from the bundle */
 423         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 424
 425         if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
 426                         return -EINVAL;
 427
 428         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
 429
 430         return 0;
 431 }
 432
 433 void arch_arm_kprobe(struct kprobe *p)
 434 {
 435         unsigned long addr = (unsigned long)p->addr;
 436         unsigned long arm_addr = addr & ~0xFULL;
 437
 438         memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
 439         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 440 }
 441
 442 void arch_disarm_kprobe(struct kprobe *p)
 443 {
 444         unsigned long addr = (unsigned long)p->addr;
 445         unsigned long arm_addr = addr & ~0xFULL;
 446
 447         /* p->opcode contains the original unaltered bundle */
 448         memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
 449         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 450 }
 451
 452 void arch_remove_kprobe(struct kprobe *p)
 453 {
 454 }
 455
 456 /*
 457  * We are resuming execution after a single step fault, so the pt_regs
 458  * structure reflects the register state after we executed the instruction
 459  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 460  * the ip to point back to the original stack address. To set the IP address
 461  * to original stack address, handle the case where we need to fixup the
 462  * relative IP address and/or fixup branch register.
 463  */
 464 static void resume_execution(struct kprobe *p, struct pt_regs *regs)
 465 {
 466         unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
 467         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 468         unsigned long template;
 469         int slot = ((unsigned long)p->addr & 0xf);
 470
 471         template = p->opcode.bundle.quad0.template;
 472
 473         if (slot == 1 && bundle_encoding[template][1] == L)
 474                 slot = 2;
 475
 476         if (p->ainsn.inst_flag) {
 477
 478                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 479                         /* Fix relative IP address */
 480                         regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
 481                 }
 482
 483                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 484                 /*
 485                  * Fix target branch register, software convention is
 486                  * to use either b0 or b6 or b7, so just checking
 487                  * only those registers
 488                  */
 489                         switch (p->ainsn.target_br_reg) {
 490                         case 0:
 491                                 if ((regs->b0 == bundle_addr) ||
 492                                         (regs->b0 == bundle_addr + 0x10)) {
 493                                         regs->b0 = (regs->b0 - bundle_addr) +
 494                                                 resume_addr;
 495                                 }
 496                                 break;
 497                         case 6:
 498                                 if ((regs->b6 == bundle_addr) ||
 499                                         (regs->b6 == bundle_addr + 0x10)) {
 500                                         regs->b6 = (regs->b6 - bundle_addr) +
 501                                                 resume_addr;
 502                                 }
 503                                 break;
 504                         case 7:
 505                                 if ((regs->b7 == bundle_addr) ||
 506                                         (regs->b7 == bundle_addr + 0x10)) {
 507                                         regs->b7 = (regs->b7 - bundle_addr) +
 508                                                 resume_addr;
 509                                 }
 510                                 break;
 511                         } /* end switch */
 512                 }
 513                 goto turn_ss_off;
 514         }
 515
 516         if (slot == 2) {
 517                 if (regs->cr_iip == bundle_addr + 0x10) {
 518                         regs->cr_iip = resume_addr + 0x10;
 519                 }
 520         } else {
 521                 if (regs->cr_iip == bundle_addr) {
 522                         regs->cr_iip = resume_addr;
 523                 }
 524         }
 525
 526 turn_ss_off:
 527         /* Turn off Single Step bit */
 528         ia64_psr(regs)->ss = 0;
 529 }
 530
 531 static void prepare_ss(struct kprobe *p, struct pt_regs *regs)
 532 {
 533         unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
 534         unsigned long slot = (unsigned long)p->addr & 0xf;
 535
 536         /* Update instruction pointer (IIP) and slot number (IPSR.ri) */
 537         regs->cr_iip = bundle_addr & ~0xFULL;
 538
 539         if (slot > 2)
 540                 slot = 0;
 541
 542         ia64_psr(regs)->ri = slot;
 543
 544         /* turn on single stepping */
 545         ia64_psr(regs)->ss = 1;
 546 }
 547
 548 static int pre_kprobes_handler(struct die_args *args)
 549 {
 550         struct kprobe *p;
 551         int ret = 0;
 552         struct pt_regs *regs = args->regs;
 553         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 554
 555         preempt_disable();
 556
 557         /* Handle recursion cases */
 558         if (kprobe_running()) {
 559                 p = get_kprobe(addr);
 560                 if (p) {
 561                         if (kprobe_status == KPROBE_HIT_SS) {
 562                                 unlock_kprobes();
 563                                 goto no_kprobe;
 564                         }
 565                         /* We have reentered the pre_kprobe_handler(), since
 566                          * another probe was hit while within the handler.
 567                          * We here save the original kprobes variables and
 568                          * just single step on the instruction of the new probe
 569                          * without calling any user handlers.
 570                          */
 571                         save_previous_kprobe();
 572                         set_current_kprobe(p);
 573                         p->nmissed++;
 574                         prepare_ss(p, regs);
 575                         kprobe_status = KPROBE_REENTER;
 576                         return 1;
 577                 } else if (args->err == __IA64_BREAK_JPROBE) {
 578                         /*
 579                          * jprobe instrumented function just completed
 580                          */
 581                         p = current_kprobe;
 582                         if (p->break_handler && p->break_handler(p, regs)) {
 583                                 goto ss_probe;
 584                         }
 585                 } else {
 586                         /* Not our break */
 587                         goto no_kprobe;
 588                 }
 589         }
 590
 591         lock_kprobes();
 592         p = get_kprobe(addr);
 593         if (!p) {
 594                 unlock_kprobes();
 595                 goto no_kprobe;
 596         }
 597
 598         kprobe_status = KPROBE_HIT_ACTIVE;
 599         set_current_kprobe(p);
 600
 601         if (p->pre_handler && p->pre_handler(p, regs))
 602                 /*
 603                  * Our pre-handler is specifically requesting that we just
 604                  * do a return.  This is used for both the jprobe pre-handler
 605                  * and the kretprobe trampoline
 606                  */
 607                 return 1;
 608
 609 ss_probe:
 610         prepare_ss(p, regs);
 611         kprobe_status = KPROBE_HIT_SS;
 612         return 1;
 613
 614 no_kprobe:
 615         preempt_enable_no_resched();
 616         return ret;
 617 }
 618
 619 static int post_kprobes_handler(struct pt_regs *regs)
 620 {
 621         if (!kprobe_running())
 622                 return 0;
 623
 624         if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
 625                 kprobe_status = KPROBE_HIT_SSDONE;
 626                 current_kprobe->post_handler(current_kprobe, regs, 0);
 627         }
 628
 629         resume_execution(current_kprobe, regs);
 630
 631         /*Restore back the original saved kprobes variables and continue. */
 632         if (kprobe_status == KPROBE_REENTER) {
 633                 restore_previous_kprobe();
 634                 goto out;
 635         }
 636
 637         unlock_kprobes();
 638
 639 out:
 640         preempt_enable_no_resched();
 641         return 1;
 642 }
 643
 644 static int kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 645 {
 646         if (!kprobe_running())
 647                 return 0;
 648
 649         if (current_kprobe->fault_handler &&
 650             current_kprobe->fault_handler(current_kprobe, regs, trapnr))
 651                 return 1;
 652
 653         if (kprobe_status & KPROBE_HIT_SS) {
 654                 resume_execution(current_kprobe, regs);
 655                 unlock_kprobes();
 656                 preempt_enable_no_resched();
 657         }
 658
 659         return 0;
 660 }
 661
 662 int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
 663                              void *data)
 664 {
 665         struct die_args *args = (struct die_args *)data;
 666         switch(val) {
 667         case DIE_BREAK:
 668                 if (pre_kprobes_handler(args))
 669                         return NOTIFY_STOP;
 670                 break;
 671         case DIE_SS:
 672                 if (post_kprobes_handler(args->regs))
 673                         return NOTIFY_STOP;
 674                 break;
 675         case DIE_PAGE_FAULT:
 676                 if (kprobes_fault_handler(args->regs, args->trapnr))
 677                         return NOTIFY_STOP;
 678         default:
 679                 break;
 680         }
 681         return NOTIFY_DONE;
 682 }
 683
 684 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 685 {
 686         struct jprobe *jp = container_of(p, struct jprobe, kp);
 687         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 688
 689         /* save architectural state */
 690         jprobe_saved_regs = *regs;
 691
 692         /* after rfi, execute the jprobe instrumented function */
 693         regs->cr_iip = addr & ~0xFULL;
 694         ia64_psr(regs)->ri = addr & 0xf;
 695         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 696
 697         /*
 698          * fix the return address to our jprobe_inst_return() function
 699          * in the jprobes.S file
 700          */
 701         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 702
 703         return 1;
 704 }
 705
 706 int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 707 {
 708         *regs = jprobe_saved_regs;
 709         return 1;
 710 }
 711
 712 static struct kprobe trampoline_p = {
 713         .pre_handler = trampoline_probe_handler
 714 };
 715
 716 int __init arch_init_kprobes(void)
 717 {
 718         trampoline_p.addr =
 719                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
 720         return register_kprobe(&trampoline_p);
 721 }