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/kprobes.h>
  27 #include <linux/ptrace.h>
  28 #include <linux/string.h>
  29 #include <linux/slab.h>
  30 #include <linux/preempt.h>
  31 #include <linux/moduleloader.h>
  32
  33 #include <asm/pgtable.h>
  34 #include <asm/kdebug.h>
  35 #include <asm/sections.h>
  36 #include <asm/uaccess.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                                       unsigned long addr)
 140 {
 141         if (bundle_encoding[template][slot] == I) {
 142                 switch (major_opcode) {
 143                         case 0x0: //I_UNIT_MISC_OPCODE:
 144                         /*
 145                          * Check for Integer speculation instruction
 146                          * - Bit 33-35 to be equal to 0x1
 147                          */
 148                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 149                                 printk(KERN_WARNING
 150                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 151                                         addr);
 152                                 return -EINVAL;
 153                         }
 154
 155                         /*
 156                          * IP relative mov instruction
 157                          *  - Bit 27-35 to be equal to 0x30
 158                          */
 159                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 160                                 printk(KERN_WARNING
 161                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 162                                         addr);
 163                                 return -EINVAL;
 164
 165                         }
 166                 }
 167         }
 168         return 0;
 169 }
 170
 171
 172 /*
 173  * In this function we check to see if the instruction
 174  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 175  * on which we are inserting kprobe is cmp instruction
 176  * with ctype as unc.
 177  */
 178 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
 179                                             uint major_opcode,
 180                                             unsigned long kprobe_inst)
 181 {
 182         cmp_inst_t cmp_inst;
 183         uint ctype_unc = 0;
 184
 185         if (!((bundle_encoding[template][slot] == I) ||
 186                 (bundle_encoding[template][slot] == M)))
 187                 goto out;
 188
 189         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 190                 (major_opcode == 0xE)))
 191                 goto out;
 192
 193         cmp_inst.l = kprobe_inst;
 194         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 195                 /* Integere compare - Register Register (A6 type)*/
 196                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 197                                 &&(cmp_inst.f.c == 1))
 198                         ctype_unc = 1;
 199         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 200                 /* Integere compare - Immediate Register (A8 type)*/
 201                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 202                         ctype_unc = 1;
 203         }
 204 out:
 205         return ctype_unc;
 206 }
 207
 208 /*
 209  * In this function we override the bundle with
 210  * the break instruction at the given slot.
 211  */
 212 static void __kprobes prepare_break_inst(uint template, uint  slot,
 213                                          uint major_opcode,
 214                                          unsigned long kprobe_inst,
 215                                          struct kprobe *p)
 216 {
 217         unsigned long break_inst = BREAK_INST;
 218         bundle_t *bundle = &p->opcode.bundle;
 219
 220         /*
 221          * Copy the original kprobe_inst qualifying predicate(qp)
 222          * to the break instruction iff !is_cmp_ctype_unc_inst
 223          * because for cmp instruction with ctype equal to unc,
 224          * which is a special instruction always needs to be
 225          * executed regradless of qp
 226          */
 227         if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
 228                 break_inst |= (0x3f & kprobe_inst);
 229
 230         switch (slot) {
 231           case 0:
 232                 bundle->quad0.slot0 = break_inst;
 233                 break;
 234           case 1:
 235                 bundle->quad0.slot1_p0 = break_inst;
 236                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 237                 break;
 238           case 2:
 239                 bundle->quad1.slot2 = break_inst;
 240                 break;
 241         }
 242
 243         /*
 244          * Update the instruction flag, so that we can
 245          * emulate the instruction properly after we
 246          * single step on original instruction
 247          */
 248         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 249 }
 250
 251 static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
 252                 unsigned long *kprobe_inst, uint *major_opcode)
 253 {
 254         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 255         unsigned int template;
 256
 257         template = bundle->quad0.template;
 258
 259         switch (slot) {
 260           case 0:
 261                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 262                 *kprobe_inst = bundle->quad0.slot0;
 263                   break;
 264           case 1:
 265                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 266                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 267                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 268                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 269                 break;
 270           case 2:
 271                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 272                 *kprobe_inst = bundle->quad1.slot2;
 273                 break;
 274         }
 275 }
 276
 277 /* Returns non-zero if the addr is in the Interrupt Vector Table */
 278 static int __kprobes in_ivt_functions(unsigned long addr)
 279 {
 280         return (addr >= (unsigned long)__start_ivt_text
 281                 && addr < (unsigned long)__end_ivt_text);
 282 }
 283
 284 static int __kprobes valid_kprobe_addr(int template, int slot,
 285                                        unsigned long addr)
 286 {
 287         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 288                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
 289                                 "at 0x%lx\n", addr);
 290                 return -EINVAL;
 291         }
 292
 293         if (in_ivt_functions(addr)) {
 294                 printk(KERN_WARNING "Kprobes can't be inserted inside "
 295                                 "IVT functions at 0x%lx\n", addr);
 296                 return -EINVAL;
 297         }
 298
 299         if (slot == 1 && bundle_encoding[template][1] != L) {
 300                 printk(KERN_WARNING "Inserting kprobes on slot #1 "
 301                        "is not supported\n");
 302                 return -EINVAL;
 303         }
 304
 305         return 0;
 306 }
 307
 308 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 309 {
 310         kcb->prev_kprobe.kp = kprobe_running();
 311         kcb->prev_kprobe.status = kcb->kprobe_status;
 312 }
 313
 314 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 315 {
 316         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 317         kcb->kprobe_status = kcb->prev_kprobe.status;
 318 }
 319
 320 static void __kprobes set_current_kprobe(struct kprobe *p,
 321                         struct kprobe_ctlblk *kcb)
 322 {
 323         __get_cpu_var(current_kprobe) = p;
 324 }
 325
 326 static void kretprobe_trampoline(void)
 327 {
 328 }
 329
 330 /*
 331  * At this point the target function has been tricked into
 332  * returning into our trampoline.  Lookup the associated instance
 333  * and then:
 334  *    - call the handler function
 335  *    - cleanup by marking the instance as unused
 336  *    - long jump back to the original return address
 337  */
 338 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 339 {
 340         struct kretprobe_instance *ri = NULL;
 341         struct hlist_head *head, empty_rp;
 342         struct hlist_node *node, *tmp;
 343         unsigned long flags, orig_ret_address = 0;
 344         unsigned long trampoline_address =
 345                 ((struct fnptr *)kretprobe_trampoline)->ip;
 346
 347         INIT_HLIST_HEAD(&empty_rp);
 348         spin_lock_irqsave(&kretprobe_lock, flags);
 349         head = kretprobe_inst_table_head(current);
 350
 351         /*
 352          * It is possible to have multiple instances associated with a given
 353          * task either because an multiple functions in the call path
 354          * have a return probe installed on them, and/or more then one return
 355          * return probe was registered for a target function.
 356          *
 357          * We can handle this because:
 358          *     - instances are always inserted at the head of the list
 359          *     - when multiple return probes are registered for the same
 360          *       function, the first instance's ret_addr will point to the
 361          *       real return address, and all the rest will point to
 362          *       kretprobe_trampoline
 363          */
 364         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 365                 if (ri->task != current)
 366                         /* another task is sharing our hash bucket */
 367                         continue;
 368
 369                 if (ri->rp && ri->rp->handler)
 370                         ri->rp->handler(ri, regs);
 371
 372                 orig_ret_address = (unsigned long)ri->ret_addr;
 373                 recycle_rp_inst(ri, &empty_rp);
 374
 375                 if (orig_ret_address != trampoline_address)
 376                         /*
 377                          * This is the real return address. Any other
 378                          * instances associated with this task are for
 379                          * other calls deeper on the call stack
 380                          */
 381                         break;
 382         }
 383
 384         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 385         regs->cr_iip = orig_ret_address;
 386
 387         reset_current_kprobe();
 388         spin_unlock_irqrestore(&kretprobe_lock, flags);
 389         preempt_enable_no_resched();
 390
 391         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 392                 hlist_del(&ri->hlist);
 393                 kfree(ri);
 394         }
 395         /*
 396          * By returning a non-zero value, we are telling
 397          * kprobe_handler() that we don't want the post_handler
 398          * to run (and have re-enabled preemption)
 399          */
 400         return 1;
 401 }
 402
 403 /* Called with kretprobe_lock held */
 404 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
 405                                       struct pt_regs *regs)
 406 {
 407         struct kretprobe_instance *ri;
 408
 409         if ((ri = get_free_rp_inst(rp)) != NULL) {
 410                 ri->rp = rp;
 411                 ri->task = current;
 412                 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 413
 414                 /* Replace the return addr with trampoline addr */
 415                 regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 416
 417                 add_rp_inst(ri);
 418         } else {
 419                 rp->nmissed++;
 420         }
 421 }
 422
 423 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 424 {
 425         unsigned long addr = (unsigned long) p->addr;
 426         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 427         unsigned long kprobe_inst=0;
 428         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 429         bundle_t *bundle;
 430
 431         bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
 432         template = bundle->quad0.template;
 433
 434         if(valid_kprobe_addr(template, slot, addr))
 435                 return -EINVAL;
 436
 437         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 438         if (slot == 1 && bundle_encoding[template][1] == L)
 439                 slot++;
 440
 441         /* Get kprobe_inst and major_opcode from the bundle */
 442         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 443
 444         if (unsupported_inst(template, slot, major_opcode, kprobe_inst, addr))
 445                         return -EINVAL;
 446
 447
 448         p->ainsn.insn = get_insn_slot();
 449         if (!p->ainsn.insn)
 450                 return -ENOMEM;
 451         memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
 452         memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
 453
 454         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
 455
 456         return 0;
 457 }
 458
 459 void __kprobes arch_arm_kprobe(struct kprobe *p)
 460 {
 461         unsigned long addr = (unsigned long)p->addr;
 462         unsigned long arm_addr = addr & ~0xFULL;
 463
 464         flush_icache_range((unsigned long)p->ainsn.insn,
 465                         (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
 466         memcpy((char *)arm_addr, &p->opcode, sizeof(kprobe_opcode_t));
 467         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 468 }
 469
 470 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 471 {
 472         unsigned long addr = (unsigned long)p->addr;
 473         unsigned long arm_addr = addr & ~0xFULL;
 474
 475         /* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
 476         memcpy((char *) arm_addr, (char *) p->ainsn.insn,
 477                                          sizeof(kprobe_opcode_t));
 478         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 479 }
 480
 481 void __kprobes arch_remove_kprobe(struct kprobe *p)
 482 {
 483         mutex_lock(&kprobe_mutex);
 484         free_insn_slot(p->ainsn.insn);
 485         mutex_unlock(&kprobe_mutex);
 486 }
 487 /*
 488  * We are resuming execution after a single step fault, so the pt_regs
 489  * structure reflects the register state after we executed the instruction
 490  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 491  * the ip to point back to the original stack address. To set the IP address
 492  * to original stack address, handle the case where we need to fixup the
 493  * relative IP address and/or fixup branch register.
 494  */
 495 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 496 {
 497         unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
 498         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 499         unsigned long template;
 500         int slot = ((unsigned long)p->addr & 0xf);
 501
 502         template = p->ainsn.insn->bundle.quad0.template;
 503
 504         if (slot == 1 && bundle_encoding[template][1] == L)
 505                 slot = 2;
 506
 507         if (p->ainsn.inst_flag) {
 508
 509                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 510                         /* Fix relative IP address */
 511                         regs->cr_iip = (regs->cr_iip - bundle_addr) +
 512                                         resume_addr;
 513                 }
 514
 515                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 516                 /*
 517                  * Fix target branch register, software convention is
 518                  * to use either b0 or b6 or b7, so just checking
 519                  * only those registers
 520                  */
 521                         switch (p->ainsn.target_br_reg) {
 522                         case 0:
 523                                 if ((regs->b0 == bundle_addr) ||
 524                                         (regs->b0 == bundle_addr + 0x10)) {
 525                                         regs->b0 = (regs->b0 - bundle_addr) +
 526                                                 resume_addr;
 527                                 }
 528                                 break;
 529                         case 6:
 530                                 if ((regs->b6 == bundle_addr) ||
 531                                         (regs->b6 == bundle_addr + 0x10)) {
 532                                         regs->b6 = (regs->b6 - bundle_addr) +
 533                                                 resume_addr;
 534                                 }
 535                                 break;
 536                         case 7:
 537                                 if ((regs->b7 == bundle_addr) ||
 538                                         (regs->b7 == bundle_addr + 0x10)) {
 539                                         regs->b7 = (regs->b7 - bundle_addr) +
 540                                                 resume_addr;
 541                                 }
 542                                 break;
 543                         } /* end switch */
 544                 }
 545                 goto turn_ss_off;
 546         }
 547
 548         if (slot == 2) {
 549                 if (regs->cr_iip == bundle_addr + 0x10) {
 550                         regs->cr_iip = resume_addr + 0x10;
 551                 }
 552         } else {
 553                 if (regs->cr_iip == bundle_addr) {
 554                         regs->cr_iip = resume_addr;
 555                 }
 556         }
 557
 558 turn_ss_off:
 559         /* Turn off Single Step bit */
 560         ia64_psr(regs)->ss = 0;
 561 }
 562
 563 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
 564 {
 565         unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
 566         unsigned long slot = (unsigned long)p->addr & 0xf;
 567
 568         /* single step inline if break instruction */
 569         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
 570                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
 571         else
 572                 regs->cr_iip = bundle_addr & ~0xFULL;
 573
 574         if (slot > 2)
 575                 slot = 0;
 576
 577         ia64_psr(regs)->ri = slot;
 578
 579         /* turn on single stepping */
 580         ia64_psr(regs)->ss = 1;
 581 }
 582
 583 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
 584 {
 585         unsigned int slot = ia64_psr(regs)->ri;
 586         unsigned int template, major_opcode;
 587         unsigned long kprobe_inst;
 588         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
 589         bundle_t bundle;
 590
 591         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
 592         template = bundle.quad0.template;
 593
 594         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 595         if (slot == 1 && bundle_encoding[template][1] == L)
 596                 slot++;
 597
 598         /* Get Kprobe probe instruction at given slot*/
 599         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
 600
 601         /* For break instruction,
 602          * Bits 37:40 Major opcode to be zero
 603          * Bits 27:32 X6 to be zero
 604          * Bits 32:35 X3 to be zero
 605          */
 606         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
 607                 /* Not a break instruction */
 608                 return 0;
 609         }
 610
 611         /* Is a break instruction */
 612         return 1;
 613 }
 614
 615 static int __kprobes pre_kprobes_handler(struct die_args *args)
 616 {
 617         struct kprobe *p;
 618         int ret = 0;
 619         struct pt_regs *regs = args->regs;
 620         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 621         struct kprobe_ctlblk *kcb;
 622
 623         /*
 624          * We don't want to be preempted for the entire
 625          * duration of kprobe processing
 626          */
 627         preempt_disable();
 628         kcb = get_kprobe_ctlblk();
 629
 630         /* Handle recursion cases */
 631         if (kprobe_running()) {
 632                 p = get_kprobe(addr);
 633                 if (p) {
 634                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
 635                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
 636                                 ia64_psr(regs)->ss = 0;
 637                                 goto no_kprobe;
 638                         }
 639                         /* We have reentered the pre_kprobe_handler(), since
 640                          * another probe was hit while within the handler.
 641                          * We here save the original kprobes variables and
 642                          * just single step on the instruction of the new probe
 643                          * without calling any user handlers.
 644                          */
 645                         save_previous_kprobe(kcb);
 646                         set_current_kprobe(p, kcb);
 647                         kprobes_inc_nmissed_count(p);
 648                         prepare_ss(p, regs);
 649                         kcb->kprobe_status = KPROBE_REENTER;
 650                         return 1;
 651                 } else if (args->err == __IA64_BREAK_JPROBE) {
 652                         /*
 653                          * jprobe instrumented function just completed
 654                          */
 655                         p = __get_cpu_var(current_kprobe);
 656                         if (p->break_handler && p->break_handler(p, regs)) {
 657                                 goto ss_probe;
 658                         }
 659                 } else if (!is_ia64_break_inst(regs)) {
 660                         /* The breakpoint instruction was removed by
 661                          * another cpu right after we hit, no further
 662                          * handling of this interrupt is appropriate
 663                          */
 664                         ret = 1;
 665                         goto no_kprobe;
 666                 } else {
 667                         /* Not our break */
 668                         goto no_kprobe;
 669                 }
 670         }
 671
 672         p = get_kprobe(addr);
 673         if (!p) {
 674                 if (!is_ia64_break_inst(regs)) {
 675                         /*
 676                          * The breakpoint instruction was removed right
 677                          * after we hit it.  Another cpu has removed
 678                          * either a probepoint or a debugger breakpoint
 679                          * at this address.  In either case, no further
 680                          * handling of this interrupt is appropriate.
 681                          */
 682                         ret = 1;
 683
 684                 }
 685
 686                 /* Not one of our break, let kernel handle it */
 687                 goto no_kprobe;
 688         }
 689
 690         set_current_kprobe(p, kcb);
 691         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 692
 693         if (p->pre_handler && p->pre_handler(p, regs))
 694                 /*
 695                  * Our pre-handler is specifically requesting that we just
 696                  * do a return.  This is used for both the jprobe pre-handler
 697                  * and the kretprobe trampoline
 698                  */
 699                 return 1;
 700
 701 ss_probe:
 702         prepare_ss(p, regs);
 703         kcb->kprobe_status = KPROBE_HIT_SS;
 704         return 1;
 705
 706 no_kprobe:
 707         preempt_enable_no_resched();
 708         return ret;
 709 }
 710
 711 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
 712 {
 713         struct kprobe *cur = kprobe_running();
 714         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 715
 716         if (!cur)
 717                 return 0;
 718
 719         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 720                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 721                 cur->post_handler(cur, regs, 0);
 722         }
 723
 724         resume_execution(cur, regs);
 725
 726         /*Restore back the original saved kprobes variables and continue. */
 727         if (kcb->kprobe_status == KPROBE_REENTER) {
 728                 restore_previous_kprobe(kcb);
 729                 goto out;
 730         }
 731         reset_current_kprobe();
 732
 733 out:
 734         preempt_enable_no_resched();
 735         return 1;
 736 }
 737
 738 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 739 {
 740         struct kprobe *cur = kprobe_running();
 741         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 742
 743
 744         switch(kcb->kprobe_status) {
 745         case KPROBE_HIT_SS:
 746         case KPROBE_REENTER:
 747                 /*
 748                  * We are here because the instruction being single
 749                  * stepped caused a page fault. We reset the current
 750                  * kprobe and the instruction pointer points back to
 751                  * the probe address and allow the page fault handler
 752                  * to continue as a normal page fault.
 753                  */
 754                 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
 755                 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
 756                 if (kcb->kprobe_status == KPROBE_REENTER)
 757                         restore_previous_kprobe(kcb);
 758                 else
 759                         reset_current_kprobe();
 760                 preempt_enable_no_resched();
 761                 break;
 762         case KPROBE_HIT_ACTIVE:
 763         case KPROBE_HIT_SSDONE:
 764                 /*
 765                  * We increment the nmissed count for accounting,
 766                  * we can also use npre/npostfault count for accouting
 767                  * these specific fault cases.
 768                  */
 769                 kprobes_inc_nmissed_count(cur);
 770
 771                 /*
 772                  * We come here because instructions in the pre/post
 773                  * handler caused the page_fault, this could happen
 774                  * if handler tries to access user space by
 775                  * copy_from_user(), get_user() etc. Let the
 776                  * user-specified handler try to fix it first.
 777                  */
 778                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 779                         return 1;
 780                 /*
 781                  * In case the user-specified fault handler returned
 782                  * zero, try to fix up.
 783                  */
 784                 if (ia64_done_with_exception(regs))
 785                         return 1;
 786
 787                 /*
 788                  * Let ia64_do_page_fault() fix it.
 789                  */
 790                 break;
 791         default:
 792                 break;
 793         }
 794
 795         return 0;
 796 }
 797
 798 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 799                                        unsigned long val, void *data)
 800 {
 801         struct die_args *args = (struct die_args *)data;
 802         int ret = NOTIFY_DONE;
 803
 804         if (args->regs && user_mode(args->regs))
 805                 return ret;
 806
 807         switch(val) {
 808         case DIE_BREAK:
 809                 /* err is break number from ia64_bad_break() */
 810                 if (args->err == 0x80200 || args->err == 0x80300 || args->err == 0)
 811                         if (pre_kprobes_handler(args))
 812                                 ret = NOTIFY_STOP;
 813                 break;
 814         case DIE_FAULT:
 815                 /* err is vector number from ia64_fault() */
 816                 if (args->err == 36)
 817                         if (post_kprobes_handler(args->regs))
 818                                 ret = NOTIFY_STOP;
 819                 break;
 820         case DIE_PAGE_FAULT:
 821                 /* kprobe_running() needs smp_processor_id() */
 822                 preempt_disable();
 823                 if (kprobe_running() &&
 824                         kprobes_fault_handler(args->regs, args->trapnr))
 825                         ret = NOTIFY_STOP;
 826                 preempt_enable();
 827         default:
 828                 break;
 829         }
 830         return ret;
 831 }
 832
 833 struct param_bsp_cfm {
 834         unsigned long ip;
 835         unsigned long *bsp;
 836         unsigned long cfm;
 837 };
 838
 839 static void ia64_get_bsp_cfm(struct unw_frame_info *info, void *arg)
 840 {
 841         unsigned long ip;
 842         struct param_bsp_cfm *lp = arg;
 843
 844         do {
 845                 unw_get_ip(info, &ip);
 846                 if (ip == 0)
 847                         break;
 848                 if (ip == lp->ip) {
 849                         unw_get_bsp(info, (unsigned long*)&lp->bsp);
 850                         unw_get_cfm(info, (unsigned long*)&lp->cfm);
 851                         return;
 852                 }
 853         } while (unw_unwind(info) >= 0);
 854         lp->bsp = 0;
 855         lp->cfm = 0;
 856         return;
 857 }
 858
 859 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 860 {
 861         struct jprobe *jp = container_of(p, struct jprobe, kp);
 862         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 863         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 864         struct param_bsp_cfm pa;
 865         int bytes;
 866
 867         /*
 868          * Callee owns the argument space and could overwrite it, eg
 869          * tail call optimization. So to be absolutely safe
 870          * we save the argument space before transfering the control
 871          * to instrumented jprobe function which runs in
 872          * the process context
 873          */
 874         pa.ip = regs->cr_iip;
 875         unw_init_running(ia64_get_bsp_cfm, &pa);
 876         bytes = (char *)ia64_rse_skip_regs(pa.bsp, pa.cfm & 0x3f)
 877                                 - (char *)pa.bsp;
 878         memcpy( kcb->jprobes_saved_stacked_regs,
 879                 pa.bsp,
 880                 bytes );
 881         kcb->bsp = pa.bsp;
 882         kcb->cfm = pa.cfm;
 883
 884         /* save architectural state */
 885         kcb->jprobe_saved_regs = *regs;
 886
 887         /* after rfi, execute the jprobe instrumented function */
 888         regs->cr_iip = addr & ~0xFULL;
 889         ia64_psr(regs)->ri = addr & 0xf;
 890         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 891
 892         /*
 893          * fix the return address to our jprobe_inst_return() function
 894          * in the jprobes.S file
 895          */
 896         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 897
 898         return 1;
 899 }
 900
 901 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 902 {
 903         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 904         int bytes;
 905
 906         /* restoring architectural state */
 907         *regs = kcb->jprobe_saved_regs;
 908
 909         /* restoring the original argument space */
 910         flush_register_stack();
 911         bytes = (char *)ia64_rse_skip_regs(kcb->bsp, kcb->cfm & 0x3f)
 912                                 - (char *)kcb->bsp;
 913         memcpy( kcb->bsp,
 914                 kcb->jprobes_saved_stacked_regs,
 915                 bytes );
 916         invalidate_stacked_regs();
 917
 918         preempt_enable_no_resched();
 919         return 1;
 920 }
 921
 922 static struct kprobe trampoline_p = {
 923         .pre_handler = trampoline_probe_handler
 924 };
 925
 926 int __init arch_init_kprobes(void)
 927 {
 928         trampoline_p.addr =
 929                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
 930         return register_kprobe(&trampoline_p);
 931 }