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 #include <linux/kdebug.h>
  33
  34 #include <asm/pgtable.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         p->ainsn.slot = slot;
  92
  93         /* Check for Break instruction
  94          * Bits 37:40 Major opcode to be zero
  95          * Bits 27:32 X6 to be zero
  96          * Bits 32:35 X3 to be zero
  97          */
  98         if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
  99                 /* is a break instruction */
 100                 p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
 101                 return;
 102         }
 103
 104         if (bundle_encoding[template][slot] == B) {
 105                 switch (major_opcode) {
 106                   case INDIRECT_CALL_OPCODE:
 107                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 108                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 109                         break;
 110                   case IP_RELATIVE_PREDICT_OPCODE:
 111                   case IP_RELATIVE_BRANCH_OPCODE:
 112                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 113                         break;
 114                   case IP_RELATIVE_CALL_OPCODE:
 115                         p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
 116                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 117                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 118                         break;
 119                 }
 120         } else if (bundle_encoding[template][slot] == X) {
 121                 switch (major_opcode) {
 122                   case LONG_CALL_OPCODE:
 123                         p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
 124                         p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
 125                   break;
 126                 }
 127         }
 128         return;
 129 }
 130
 131 /*
 132  * In this function we check to see if the instruction
 133  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 134  * on which we are inserting kprobe is cmp instruction
 135  * with ctype as unc.
 136  */
 137 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
 138                                             uint major_opcode,
 139                                             unsigned long kprobe_inst)
 140 {
 141         cmp_inst_t cmp_inst;
 142         uint ctype_unc = 0;
 143
 144         if (!((bundle_encoding[template][slot] == I) ||
 145                 (bundle_encoding[template][slot] == M)))
 146                 goto out;
 147
 148         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 149                 (major_opcode == 0xE)))
 150                 goto out;
 151
 152         cmp_inst.l = kprobe_inst;
 153         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 154                 /* Integere compare - Register Register (A6 type)*/
 155                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 156                                 &&(cmp_inst.f.c == 1))
 157                         ctype_unc = 1;
 158         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 159                 /* Integere compare - Immediate Register (A8 type)*/
 160                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 161                         ctype_unc = 1;
 162         }
 163 out:
 164         return ctype_unc;
 165 }
 166
 167 /*
 168  * In this function we check to see if the instruction
 169  * on which we are inserting kprobe is supported.
 170  * Returns qp value if supported
 171  * Returns -EINVAL if unsupported
 172  */
 173 static int __kprobes unsupported_inst(uint template, uint  slot,
 174                                       uint major_opcode,
 175                                       unsigned long kprobe_inst,
 176                                       unsigned long addr)
 177 {
 178         int qp;
 179
 180         qp = kprobe_inst & 0x3f;
 181         if (is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst)) {
 182                 if (slot == 1 && qp)  {
 183                         printk(KERN_WARNING "Kprobes on cmp unc"
 184                                         "instruction on slot 1 at <0x%lx>"
 185                                         "is not supported\n", addr);
 186                         return -EINVAL;
 187
 188                 }
 189                 qp = 0;
 190         }
 191         else if (bundle_encoding[template][slot] == I) {
 192                 if (major_opcode == 0) {
 193                         /*
 194                          * Check for Integer speculation instruction
 195                          * - Bit 33-35 to be equal to 0x1
 196                          */
 197                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 198                                 printk(KERN_WARNING
 199                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 200                                                 addr);
 201                                 return -EINVAL;
 202                         }
 203                         /*
 204                          * IP relative mov instruction
 205                          *  - Bit 27-35 to be equal to 0x30
 206                          */
 207                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 208                                 printk(KERN_WARNING
 209                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 210                                                 addr);
 211                                 return -EINVAL;
 212
 213                         }
 214                 }
 215                 else if ((major_opcode == 5) && !(kprobe_inst & (0xFUl << 33)) &&
 216                                 (kprobe_inst & (0x1UL << 12))) {
 217                         /* test bit instructions, tbit,tnat,tf
 218                          * bit 33-36 to be equal to 0
 219                          * bit 12 to be equal to 1
 220                          */
 221                         if (slot == 1 && qp) {
 222                                 printk(KERN_WARNING "Kprobes on test bit"
 223                                                 "instruction on slot at <0x%lx>"
 224                                                 "is not supported\n", addr);
 225                                 return -EINVAL;
 226                         }
 227                         qp = 0;
 228                 }
 229         }
 230         else if (bundle_encoding[template][slot] == B) {
 231                 if (major_opcode == 7) {
 232                         /* IP-Relative Predict major code is 7 */
 233                         printk(KERN_WARNING "Kprobes on IP-Relative"
 234                                         "Predict is not supported\n");
 235                         return -EINVAL;
 236                 }
 237                 else if (major_opcode == 2) {
 238                         /* Indirect Predict, major code is 2
 239                          * bit 27-32 to be equal to 10 or 11
 240                          */
 241                         int x6=(kprobe_inst >> 27) & 0x3F;
 242                         if ((x6 == 0x10) || (x6 == 0x11)) {
 243                                 printk(KERN_WARNING "Kprobes on"
 244                                         "Indirect Predict is not supported\n");
 245                                 return -EINVAL;
 246                         }
 247                 }
 248         }
 249         /* kernel does not use float instruction, here for safety kprobe
 250          * will judge whether it is fcmp/flass/float approximation instruction
 251          */
 252         else if (unlikely(bundle_encoding[template][slot] == F)) {
 253                 if ((major_opcode == 4 || major_opcode == 5) &&
 254                                 (kprobe_inst  & (0x1 << 12))) {
 255                         /* fcmp/fclass unc instruction */
 256                         if (slot == 1 && qp) {
 257                                 printk(KERN_WARNING "Kprobes on fcmp/fclass "
 258                                         "instruction on slot at <0x%lx> "
 259                                         "is not supported\n", addr);
 260                                 return -EINVAL;
 261
 262                         }
 263                         qp = 0;
 264                 }
 265                 if ((major_opcode == 0 || major_opcode == 1) &&
 266                         (kprobe_inst & (0x1UL << 33))) {
 267                         /* float Approximation instruction */
 268                         if (slot == 1 && qp) {
 269                                 printk(KERN_WARNING "Kprobes on float Approx "
 270                                         "instr at <0x%lx> is not supported\n",
 271                                                 addr);
 272                                 return -EINVAL;
 273                         }
 274                         qp = 0;
 275                 }
 276         }
 277         return qp;
 278 }
 279
 280 /*
 281  * In this function we override the bundle with
 282  * the break instruction at the given slot.
 283  */
 284 static void __kprobes prepare_break_inst(uint template, uint  slot,
 285                                          uint major_opcode,
 286                                          unsigned long kprobe_inst,
 287                                          struct kprobe *p,
 288                                          int qp)
 289 {
 290         unsigned long break_inst = BREAK_INST;
 291         bundle_t *bundle = &p->opcode.bundle;
 292
 293         /*
 294          * Copy the original kprobe_inst qualifying predicate(qp)
 295          * to the break instruction
 296          */
 297         break_inst |= qp;
 298
 299         switch (slot) {
 300           case 0:
 301                 bundle->quad0.slot0 = break_inst;
 302                 break;
 303           case 1:
 304                 bundle->quad0.slot1_p0 = break_inst;
 305                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 306                 break;
 307           case 2:
 308                 bundle->quad1.slot2 = break_inst;
 309                 break;
 310         }
 311
 312         /*
 313          * Update the instruction flag, so that we can
 314          * emulate the instruction properly after we
 315          * single step on original instruction
 316          */
 317         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 318 }
 319
 320 static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
 321                 unsigned long *kprobe_inst, uint *major_opcode)
 322 {
 323         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 324         unsigned int template;
 325
 326         template = bundle->quad0.template;
 327
 328         switch (slot) {
 329           case 0:
 330                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 331                 *kprobe_inst = bundle->quad0.slot0;
 332                   break;
 333           case 1:
 334                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 335                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 336                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 337                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 338                 break;
 339           case 2:
 340                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 341                 *kprobe_inst = bundle->quad1.slot2;
 342                 break;
 343         }
 344 }
 345
 346 /* Returns non-zero if the addr is in the Interrupt Vector Table */
 347 static int __kprobes in_ivt_functions(unsigned long addr)
 348 {
 349         return (addr >= (unsigned long)__start_ivt_text
 350                 && addr < (unsigned long)__end_ivt_text);
 351 }
 352
 353 static int __kprobes valid_kprobe_addr(int template, int slot,
 354                                        unsigned long addr)
 355 {
 356         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 357                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
 358                                 "at 0x%lx\n", addr);
 359                 return -EINVAL;
 360         }
 361
 362         if (in_ivt_functions(addr)) {
 363                 printk(KERN_WARNING "Kprobes can't be inserted inside "
 364                                 "IVT functions at 0x%lx\n", addr);
 365                 return -EINVAL;
 366         }
 367
 368         return 0;
 369 }
 370
 371 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 372 {
 373         kcb->prev_kprobe.kp = kprobe_running();
 374         kcb->prev_kprobe.status = kcb->kprobe_status;
 375 }
 376
 377 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 378 {
 379         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 380         kcb->kprobe_status = kcb->prev_kprobe.status;
 381 }
 382
 383 static void __kprobes set_current_kprobe(struct kprobe *p,
 384                         struct kprobe_ctlblk *kcb)
 385 {
 386         __get_cpu_var(current_kprobe) = p;
 387 }
 388
 389 static void kretprobe_trampoline(void)
 390 {
 391 }
 392
 393 /*
 394  * At this point the target function has been tricked into
 395  * returning into our trampoline.  Lookup the associated instance
 396  * and then:
 397  *    - call the handler function
 398  *    - cleanup by marking the instance as unused
 399  *    - long jump back to the original return address
 400  */
 401 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 402 {
 403         struct kretprobe_instance *ri = NULL;
 404         struct hlist_head *head, empty_rp;
 405         struct hlist_node *node, *tmp;
 406         unsigned long flags, orig_ret_address = 0;
 407         unsigned long trampoline_address =
 408                 ((struct fnptr *)kretprobe_trampoline)->ip;
 409
 410         INIT_HLIST_HEAD(&empty_rp);
 411         spin_lock_irqsave(&kretprobe_lock, flags);
 412         head = kretprobe_inst_table_head(current);
 413
 414         /*
 415          * It is possible to have multiple instances associated with a given
 416          * task either because an multiple functions in the call path
 417          * have a return probe installed on them, and/or more then one return
 418          * return probe was registered for a target function.
 419          *
 420          * We can handle this because:
 421          *     - instances are always inserted at the head of the list
 422          *     - when multiple return probes are registered for the same
 423          *       function, the first instance's ret_addr will point to the
 424          *       real return address, and all the rest will point to
 425          *       kretprobe_trampoline
 426          */
 427         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 428                 if (ri->task != current)
 429                         /* another task is sharing our hash bucket */
 430                         continue;
 431
 432                 if (ri->rp && ri->rp->handler)
 433                         ri->rp->handler(ri, regs);
 434
 435                 orig_ret_address = (unsigned long)ri->ret_addr;
 436                 recycle_rp_inst(ri, &empty_rp);
 437
 438                 if (orig_ret_address != trampoline_address)
 439                         /*
 440                          * This is the real return address. Any other
 441                          * instances associated with this task are for
 442                          * other calls deeper on the call stack
 443                          */
 444                         break;
 445         }
 446
 447         kretprobe_assert(ri, orig_ret_address, trampoline_address);
 448
 449         regs->cr_iip = orig_ret_address;
 450
 451         reset_current_kprobe();
 452         spin_unlock_irqrestore(&kretprobe_lock, flags);
 453         preempt_enable_no_resched();
 454
 455         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 456                 hlist_del(&ri->hlist);
 457                 kfree(ri);
 458         }
 459         /*
 460          * By returning a non-zero value, we are telling
 461          * kprobe_handler() that we don't want the post_handler
 462          * to run (and have re-enabled preemption)
 463          */
 464         return 1;
 465 }
 466
 467 /* Called with kretprobe_lock held */
 468 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 469                                       struct pt_regs *regs)
 470 {
 471         ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 472
 473         /* Replace the return addr with trampoline addr */
 474         regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 475 }
 476
 477 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 478 {
 479         unsigned long addr = (unsigned long) p->addr;
 480         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 481         unsigned long kprobe_inst=0;
 482         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 483         bundle_t *bundle;
 484         int qp;
 485
 486         bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
 487         template = bundle->quad0.template;
 488
 489         if(valid_kprobe_addr(template, slot, addr))
 490                 return -EINVAL;
 491
 492         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 493         if (slot == 1 && bundle_encoding[template][1] == L)
 494                 slot++;
 495
 496         /* Get kprobe_inst and major_opcode from the bundle */
 497         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 498
 499         qp = unsupported_inst(template, slot, major_opcode, kprobe_inst, addr);
 500         if (qp < 0)
 501                 return -EINVAL;
 502
 503         p->ainsn.insn = get_insn_slot();
 504         if (!p->ainsn.insn)
 505                 return -ENOMEM;
 506         memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
 507         memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
 508
 509         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p, qp);
 510
 511         return 0;
 512 }
 513
 514 void __kprobes arch_arm_kprobe(struct kprobe *p)
 515 {
 516         unsigned long arm_addr;
 517         bundle_t *src, *dest;
 518
 519         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
 520         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
 521         src = &p->opcode.bundle;
 522
 523         flush_icache_range((unsigned long)p->ainsn.insn,
 524                         (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
 525         switch (p->ainsn.slot) {
 526                 case 0:
 527                         dest->quad0.slot0 = src->quad0.slot0;
 528                         break;
 529                 case 1:
 530                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
 531                         break;
 532                 case 2:
 533                         dest->quad1.slot2 = src->quad1.slot2;
 534                         break;
 535         }
 536         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 537 }
 538
 539 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 540 {
 541         unsigned long arm_addr;
 542         bundle_t *src, *dest;
 543
 544         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
 545         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
 546         /* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
 547         src = &p->ainsn.insn->bundle;
 548         switch (p->ainsn.slot) {
 549                 case 0:
 550                         dest->quad0.slot0 = src->quad0.slot0;
 551                         break;
 552                 case 1:
 553                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
 554                         break;
 555                 case 2:
 556                         dest->quad1.slot2 = src->quad1.slot2;
 557                         break;
 558         }
 559         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 560 }
 561
 562 void __kprobes arch_remove_kprobe(struct kprobe *p)
 563 {
 564         mutex_lock(&kprobe_mutex);
 565         free_insn_slot(p->ainsn.insn, 0);
 566         mutex_unlock(&kprobe_mutex);
 567 }
 568 /*
 569  * We are resuming execution after a single step fault, so the pt_regs
 570  * structure reflects the register state after we executed the instruction
 571  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 572  * the ip to point back to the original stack address. To set the IP address
 573  * to original stack address, handle the case where we need to fixup the
 574  * relative IP address and/or fixup branch register.
 575  */
 576 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 577 {
 578         unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
 579         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 580         unsigned long template;
 581         int slot = ((unsigned long)p->addr & 0xf);
 582
 583         template = p->ainsn.insn->bundle.quad0.template;
 584
 585         if (slot == 1 && bundle_encoding[template][1] == L)
 586                 slot = 2;
 587
 588         if (p->ainsn.inst_flag) {
 589
 590                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 591                         /* Fix relative IP address */
 592                         regs->cr_iip = (regs->cr_iip - bundle_addr) +
 593                                         resume_addr;
 594                 }
 595
 596                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 597                 /*
 598                  * Fix target branch register, software convention is
 599                  * to use either b0 or b6 or b7, so just checking
 600                  * only those registers
 601                  */
 602                         switch (p->ainsn.target_br_reg) {
 603                         case 0:
 604                                 if ((regs->b0 == bundle_addr) ||
 605                                         (regs->b0 == bundle_addr + 0x10)) {
 606                                         regs->b0 = (regs->b0 - bundle_addr) +
 607                                                 resume_addr;
 608                                 }
 609                                 break;
 610                         case 6:
 611                                 if ((regs->b6 == bundle_addr) ||
 612                                         (regs->b6 == bundle_addr + 0x10)) {
 613                                         regs->b6 = (regs->b6 - bundle_addr) +
 614                                                 resume_addr;
 615                                 }
 616                                 break;
 617                         case 7:
 618                                 if ((regs->b7 == bundle_addr) ||
 619                                         (regs->b7 == bundle_addr + 0x10)) {
 620                                         regs->b7 = (regs->b7 - bundle_addr) +
 621                                                 resume_addr;
 622                                 }
 623                                 break;
 624                         } /* end switch */
 625                 }
 626                 goto turn_ss_off;
 627         }
 628
 629         if (slot == 2) {
 630                 if (regs->cr_iip == bundle_addr + 0x10) {
 631                         regs->cr_iip = resume_addr + 0x10;
 632                 }
 633         } else {
 634                 if (regs->cr_iip == bundle_addr) {
 635                         regs->cr_iip = resume_addr;
 636                 }
 637         }
 638
 639 turn_ss_off:
 640         /* Turn off Single Step bit */
 641         ia64_psr(regs)->ss = 0;
 642 }
 643
 644 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
 645 {
 646         unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
 647         unsigned long slot = (unsigned long)p->addr & 0xf;
 648
 649         /* single step inline if break instruction */
 650         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
 651                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
 652         else
 653                 regs->cr_iip = bundle_addr & ~0xFULL;
 654
 655         if (slot > 2)
 656                 slot = 0;
 657
 658         ia64_psr(regs)->ri = slot;
 659
 660         /* turn on single stepping */
 661         ia64_psr(regs)->ss = 1;
 662 }
 663
 664 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
 665 {
 666         unsigned int slot = ia64_psr(regs)->ri;
 667         unsigned int template, major_opcode;
 668         unsigned long kprobe_inst;
 669         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
 670         bundle_t bundle;
 671
 672         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
 673         template = bundle.quad0.template;
 674
 675         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 676         if (slot == 1 && bundle_encoding[template][1] == L)
 677                 slot++;
 678
 679         /* Get Kprobe probe instruction at given slot*/
 680         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
 681
 682         /* For break instruction,
 683          * Bits 37:40 Major opcode to be zero
 684          * Bits 27:32 X6 to be zero
 685          * Bits 32:35 X3 to be zero
 686          */
 687         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
 688                 /* Not a break instruction */
 689                 return 0;
 690         }
 691
 692         /* Is a break instruction */
 693         return 1;
 694 }
 695
 696 static int __kprobes pre_kprobes_handler(struct die_args *args)
 697 {
 698         struct kprobe *p;
 699         int ret = 0;
 700         struct pt_regs *regs = args->regs;
 701         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 702         struct kprobe_ctlblk *kcb;
 703
 704         /*
 705          * We don't want to be preempted for the entire
 706          * duration of kprobe processing
 707          */
 708         preempt_disable();
 709         kcb = get_kprobe_ctlblk();
 710
 711         /* Handle recursion cases */
 712         if (kprobe_running()) {
 713                 p = get_kprobe(addr);
 714                 if (p) {
 715                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
 716                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
 717                                 ia64_psr(regs)->ss = 0;
 718                                 goto no_kprobe;
 719                         }
 720                         /* We have reentered the pre_kprobe_handler(), since
 721                          * another probe was hit while within the handler.
 722                          * We here save the original kprobes variables and
 723                          * just single step on the instruction of the new probe
 724                          * without calling any user handlers.
 725                          */
 726                         save_previous_kprobe(kcb);
 727                         set_current_kprobe(p, kcb);
 728                         kprobes_inc_nmissed_count(p);
 729                         prepare_ss(p, regs);
 730                         kcb->kprobe_status = KPROBE_REENTER;
 731                         return 1;
 732                 } else if (args->err == __IA64_BREAK_JPROBE) {
 733                         /*
 734                          * jprobe instrumented function just completed
 735                          */
 736                         p = __get_cpu_var(current_kprobe);
 737                         if (p->break_handler && p->break_handler(p, regs)) {
 738                                 goto ss_probe;
 739                         }
 740                 } else if (!is_ia64_break_inst(regs)) {
 741                         /* The breakpoint instruction was removed by
 742                          * another cpu right after we hit, no further
 743                          * handling of this interrupt is appropriate
 744                          */
 745                         ret = 1;
 746                         goto no_kprobe;
 747                 } else {
 748                         /* Not our break */
 749                         goto no_kprobe;
 750                 }
 751         }
 752
 753         p = get_kprobe(addr);
 754         if (!p) {
 755                 if (!is_ia64_break_inst(regs)) {
 756                         /*
 757                          * The breakpoint instruction was removed right
 758                          * after we hit it.  Another cpu has removed
 759                          * either a probepoint or a debugger breakpoint
 760                          * at this address.  In either case, no further
 761                          * handling of this interrupt is appropriate.
 762                          */
 763                         ret = 1;
 764
 765                 }
 766
 767                 /* Not one of our break, let kernel handle it */
 768                 goto no_kprobe;
 769         }
 770
 771         set_current_kprobe(p, kcb);
 772         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 773
 774         if (p->pre_handler && p->pre_handler(p, regs))
 775                 /*
 776                  * Our pre-handler is specifically requesting that we just
 777                  * do a return.  This is used for both the jprobe pre-handler
 778                  * and the kretprobe trampoline
 779                  */
 780                 return 1;
 781
 782 ss_probe:
 783         prepare_ss(p, regs);
 784         kcb->kprobe_status = KPROBE_HIT_SS;
 785         return 1;
 786
 787 no_kprobe:
 788         preempt_enable_no_resched();
 789         return ret;
 790 }
 791
 792 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
 793 {
 794         struct kprobe *cur = kprobe_running();
 795         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 796
 797         if (!cur)
 798                 return 0;
 799
 800         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 801                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 802                 cur->post_handler(cur, regs, 0);
 803         }
 804
 805         resume_execution(cur, regs);
 806
 807         /*Restore back the original saved kprobes variables and continue. */
 808         if (kcb->kprobe_status == KPROBE_REENTER) {
 809                 restore_previous_kprobe(kcb);
 810                 goto out;
 811         }
 812         reset_current_kprobe();
 813
 814 out:
 815         preempt_enable_no_resched();
 816         return 1;
 817 }
 818
 819 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 820 {
 821         struct kprobe *cur = kprobe_running();
 822         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 823
 824
 825         switch(kcb->kprobe_status) {
 826         case KPROBE_HIT_SS:
 827         case KPROBE_REENTER:
 828                 /*
 829                  * We are here because the instruction being single
 830                  * stepped caused a page fault. We reset the current
 831                  * kprobe and the instruction pointer points back to
 832                  * the probe address and allow the page fault handler
 833                  * to continue as a normal page fault.
 834                  */
 835                 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
 836                 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
 837                 if (kcb->kprobe_status == KPROBE_REENTER)
 838                         restore_previous_kprobe(kcb);
 839                 else
 840                         reset_current_kprobe();
 841                 preempt_enable_no_resched();
 842                 break;
 843         case KPROBE_HIT_ACTIVE:
 844         case KPROBE_HIT_SSDONE:
 845                 /*
 846                  * We increment the nmissed count for accounting,
 847                  * we can also use npre/npostfault count for accouting
 848                  * these specific fault cases.
 849                  */
 850                 kprobes_inc_nmissed_count(cur);
 851
 852                 /*
 853                  * We come here because instructions in the pre/post
 854                  * handler caused the page_fault, this could happen
 855                  * if handler tries to access user space by
 856                  * copy_from_user(), get_user() etc. Let the
 857                  * user-specified handler try to fix it first.
 858                  */
 859                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 860                         return 1;
 861                 /*
 862                  * In case the user-specified fault handler returned
 863                  * zero, try to fix up.
 864                  */
 865                 if (ia64_done_with_exception(regs))
 866                         return 1;
 867
 868                 /*
 869                  * Let ia64_do_page_fault() fix it.
 870                  */
 871                 break;
 872         default:
 873                 break;
 874         }
 875
 876         return 0;
 877 }
 878
 879 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 880                                        unsigned long val, void *data)
 881 {
 882         struct die_args *args = (struct die_args *)data;
 883         int ret = NOTIFY_DONE;
 884
 885         if (args->regs && user_mode(args->regs))
 886                 return ret;
 887
 888         switch(val) {
 889         case DIE_BREAK:
 890                 /* err is break number from ia64_bad_break() */
 891                 if ((args->err >> 12) == (__IA64_BREAK_KPROBE >> 12)
 892                         || args->err == __IA64_BREAK_JPROBE
 893                         || args->err == 0)
 894                         if (pre_kprobes_handler(args))
 895                                 ret = NOTIFY_STOP;
 896                 break;
 897         case DIE_FAULT:
 898                 /* err is vector number from ia64_fault() */
 899                 if (args->err == 36)
 900                         if (post_kprobes_handler(args->regs))
 901                                 ret = NOTIFY_STOP;
 902                 break;
 903         case DIE_PAGE_FAULT:
 904                 /* kprobe_running() needs smp_processor_id() */
 905                 preempt_disable();
 906                 if (kprobe_running() &&
 907                         kprobes_fault_handler(args->regs, args->trapnr))
 908                         ret = NOTIFY_STOP;
 909                 preempt_enable();
 910         default:
 911                 break;
 912         }
 913         return ret;
 914 }
 915
 916 struct param_bsp_cfm {
 917         unsigned long ip;
 918         unsigned long *bsp;
 919         unsigned long cfm;
 920 };
 921
 922 static void ia64_get_bsp_cfm(struct unw_frame_info *info, void *arg)
 923 {
 924         unsigned long ip;
 925         struct param_bsp_cfm *lp = arg;
 926
 927         do {
 928                 unw_get_ip(info, &ip);
 929                 if (ip == 0)
 930                         break;
 931                 if (ip == lp->ip) {
 932                         unw_get_bsp(info, (unsigned long*)&lp->bsp);
 933                         unw_get_cfm(info, (unsigned long*)&lp->cfm);
 934                         return;
 935                 }
 936         } while (unw_unwind(info) >= 0);
 937         lp->bsp = NULL;
 938         lp->cfm = 0;
 939         return;
 940 }
 941
 942 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 943 {
 944         struct jprobe *jp = container_of(p, struct jprobe, kp);
 945         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 946         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 947         struct param_bsp_cfm pa;
 948         int bytes;
 949
 950         /*
 951          * Callee owns the argument space and could overwrite it, eg
 952          * tail call optimization. So to be absolutely safe
 953          * we save the argument space before transfering the control
 954          * to instrumented jprobe function which runs in
 955          * the process context
 956          */
 957         pa.ip = regs->cr_iip;
 958         unw_init_running(ia64_get_bsp_cfm, &pa);
 959         bytes = (char *)ia64_rse_skip_regs(pa.bsp, pa.cfm & 0x3f)
 960                                 - (char *)pa.bsp;
 961         memcpy( kcb->jprobes_saved_stacked_regs,
 962                 pa.bsp,
 963                 bytes );
 964         kcb->bsp = pa.bsp;
 965         kcb->cfm = pa.cfm;
 966
 967         /* save architectural state */
 968         kcb->jprobe_saved_regs = *regs;
 969
 970         /* after rfi, execute the jprobe instrumented function */
 971         regs->cr_iip = addr & ~0xFULL;
 972         ia64_psr(regs)->ri = addr & 0xf;
 973         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 974
 975         /*
 976          * fix the return address to our jprobe_inst_return() function
 977          * in the jprobes.S file
 978          */
 979         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 980
 981         return 1;
 982 }
 983
 984 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 985 {
 986         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 987         int bytes;
 988
 989         /* restoring architectural state */
 990         *regs = kcb->jprobe_saved_regs;
 991
 992         /* restoring the original argument space */
 993         flush_register_stack();
 994         bytes = (char *)ia64_rse_skip_regs(kcb->bsp, kcb->cfm & 0x3f)
 995                                 - (char *)kcb->bsp;
 996         memcpy( kcb->bsp,
 997                 kcb->jprobes_saved_stacked_regs,
 998                 bytes );
 999         invalidate_stacked_regs();
1000
1001         preempt_enable_no_resched();
1002         return 1;
1003 }
1004
1005 static struct kprobe trampoline_p = {
1006         .pre_handler = trampoline_probe_handler
1007 };
1008
1009 int __init arch_init_kprobes(void)
1010 {
1011         trampoline_p.addr =
1012                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
1013         return register_kprobe(&trampoline_p);
1014 }
1015
1016 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
1017 {
1018         if (p->addr ==
1019                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip)
1020                 return 1;
1021
1022         return 0;
1023 }