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                 /* Integer 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                 /* Integer 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         unsigned int i;
 374         i = atomic_add_return(1, &kcb->prev_kprobe_index);
 375         kcb->prev_kprobe[i-1].kp = kprobe_running();
 376         kcb->prev_kprobe[i-1].status = kcb->kprobe_status;
 377 }
 378
 379 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 380 {
 381         unsigned int i;
 382         i = atomic_sub_return(1, &kcb->prev_kprobe_index);
 383         __get_cpu_var(current_kprobe) = kcb->prev_kprobe[i].kp;
 384         kcb->kprobe_status = kcb->prev_kprobe[i].status;
 385 }
 386
 387 static void __kprobes set_current_kprobe(struct kprobe *p,
 388                         struct kprobe_ctlblk *kcb)
 389 {
 390         __get_cpu_var(current_kprobe) = p;
 391 }
 392
 393 static void kretprobe_trampoline(void)
 394 {
 395 }
 396
 397 /*
 398  * At this point the target function has been tricked into
 399  * returning into our trampoline.  Lookup the associated instance
 400  * and then:
 401  *    - call the handler function
 402  *    - cleanup by marking the instance as unused
 403  *    - long jump back to the original return address
 404  */
 405 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 406 {
 407         struct kretprobe_instance *ri = NULL;
 408         struct hlist_head *head, empty_rp;
 409         struct hlist_node *node, *tmp;
 410         unsigned long flags, orig_ret_address = 0;
 411         unsigned long trampoline_address =
 412                 ((struct fnptr *)kretprobe_trampoline)->ip;
 413
 414         INIT_HLIST_HEAD(&empty_rp);
 415         spin_lock_irqsave(&kretprobe_lock, flags);
 416         head = kretprobe_inst_table_head(current);
 417
 418         /*
 419          * It is possible to have multiple instances associated with a given
 420          * task either because an multiple functions in the call path
 421          * have a return probe installed on them, and/or more then one return
 422          * return probe was registered for a target function.
 423          *
 424          * We can handle this because:
 425          *     - instances are always inserted at the head of the list
 426          *     - when multiple return probes are registered for the same
 427          *       function, the first instance's ret_addr will point to the
 428          *       real return address, and all the rest will point to
 429          *       kretprobe_trampoline
 430          */
 431         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 432                 if (ri->task != current)
 433                         /* another task is sharing our hash bucket */
 434                         continue;
 435
 436                 if (ri->rp && ri->rp->handler)
 437                         ri->rp->handler(ri, regs);
 438
 439                 orig_ret_address = (unsigned long)ri->ret_addr;
 440                 recycle_rp_inst(ri, &empty_rp);
 441
 442                 if (orig_ret_address != trampoline_address)
 443                         /*
 444                          * This is the real return address. Any other
 445                          * instances associated with this task are for
 446                          * other calls deeper on the call stack
 447                          */
 448                         break;
 449         }
 450
 451         kretprobe_assert(ri, orig_ret_address, trampoline_address);
 452
 453         regs->cr_iip = orig_ret_address;
 454
 455         reset_current_kprobe();
 456         spin_unlock_irqrestore(&kretprobe_lock, flags);
 457         preempt_enable_no_resched();
 458
 459         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 460                 hlist_del(&ri->hlist);
 461                 kfree(ri);
 462         }
 463         /*
 464          * By returning a non-zero value, we are telling
 465          * kprobe_handler() that we don't want the post_handler
 466          * to run (and have re-enabled preemption)
 467          */
 468         return 1;
 469 }
 470
 471 /* Called with kretprobe_lock held */
 472 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 473                                       struct pt_regs *regs)
 474 {
 475         ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 476
 477         /* Replace the return addr with trampoline addr */
 478         regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 479 }
 480
 481 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 482 {
 483         unsigned long addr = (unsigned long) p->addr;
 484         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 485         unsigned long kprobe_inst=0;
 486         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 487         bundle_t *bundle;
 488         int qp;
 489
 490         bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
 491         template = bundle->quad0.template;
 492
 493         if(valid_kprobe_addr(template, slot, addr))
 494                 return -EINVAL;
 495
 496         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 497         if (slot == 1 && bundle_encoding[template][1] == L)
 498                 slot++;
 499
 500         /* Get kprobe_inst and major_opcode from the bundle */
 501         get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
 502
 503         qp = unsupported_inst(template, slot, major_opcode, kprobe_inst, addr);
 504         if (qp < 0)
 505                 return -EINVAL;
 506
 507         p->ainsn.insn = get_insn_slot();
 508         if (!p->ainsn.insn)
 509                 return -ENOMEM;
 510         memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
 511         memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
 512
 513         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p, qp);
 514
 515         return 0;
 516 }
 517
 518 void __kprobes arch_arm_kprobe(struct kprobe *p)
 519 {
 520         unsigned long arm_addr;
 521         bundle_t *src, *dest;
 522
 523         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
 524         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
 525         src = &p->opcode.bundle;
 526
 527         flush_icache_range((unsigned long)p->ainsn.insn,
 528                         (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t));
 529         switch (p->ainsn.slot) {
 530                 case 0:
 531                         dest->quad0.slot0 = src->quad0.slot0;
 532                         break;
 533                 case 1:
 534                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
 535                         break;
 536                 case 2:
 537                         dest->quad1.slot2 = src->quad1.slot2;
 538                         break;
 539         }
 540         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 541 }
 542
 543 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 544 {
 545         unsigned long arm_addr;
 546         bundle_t *src, *dest;
 547
 548         arm_addr = ((unsigned long)p->addr) & ~0xFUL;
 549         dest = &((kprobe_opcode_t *)arm_addr)->bundle;
 550         /* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
 551         src = &p->ainsn.insn->bundle;
 552         switch (p->ainsn.slot) {
 553                 case 0:
 554                         dest->quad0.slot0 = src->quad0.slot0;
 555                         break;
 556                 case 1:
 557                         dest->quad1.slot1_p1 = src->quad1.slot1_p1;
 558                         break;
 559                 case 2:
 560                         dest->quad1.slot2 = src->quad1.slot2;
 561                         break;
 562         }
 563         flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
 564 }
 565
 566 void __kprobes arch_remove_kprobe(struct kprobe *p)
 567 {
 568         mutex_lock(&kprobe_mutex);
 569         free_insn_slot(p->ainsn.insn, 0);
 570         mutex_unlock(&kprobe_mutex);
 571 }
 572 /*
 573  * We are resuming execution after a single step fault, so the pt_regs
 574  * structure reflects the register state after we executed the instruction
 575  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 576  * the ip to point back to the original stack address. To set the IP address
 577  * to original stack address, handle the case where we need to fixup the
 578  * relative IP address and/or fixup branch register.
 579  */
 580 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 581 {
 582         unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
 583         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 584         unsigned long template;
 585         int slot = ((unsigned long)p->addr & 0xf);
 586
 587         template = p->ainsn.insn->bundle.quad0.template;
 588
 589         if (slot == 1 && bundle_encoding[template][1] == L)
 590                 slot = 2;
 591
 592         if (p->ainsn.inst_flag) {
 593
 594                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 595                         /* Fix relative IP address */
 596                         regs->cr_iip = (regs->cr_iip - bundle_addr) +
 597                                         resume_addr;
 598                 }
 599
 600                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 601                 /*
 602                  * Fix target branch register, software convention is
 603                  * to use either b0 or b6 or b7, so just checking
 604                  * only those registers
 605                  */
 606                         switch (p->ainsn.target_br_reg) {
 607                         case 0:
 608                                 if ((regs->b0 == bundle_addr) ||
 609                                         (regs->b0 == bundle_addr + 0x10)) {
 610                                         regs->b0 = (regs->b0 - bundle_addr) +
 611                                                 resume_addr;
 612                                 }
 613                                 break;
 614                         case 6:
 615                                 if ((regs->b6 == bundle_addr) ||
 616                                         (regs->b6 == bundle_addr + 0x10)) {
 617                                         regs->b6 = (regs->b6 - bundle_addr) +
 618                                                 resume_addr;
 619                                 }
 620                                 break;
 621                         case 7:
 622                                 if ((regs->b7 == bundle_addr) ||
 623                                         (regs->b7 == bundle_addr + 0x10)) {
 624                                         regs->b7 = (regs->b7 - bundle_addr) +
 625                                                 resume_addr;
 626                                 }
 627                                 break;
 628                         } /* end switch */
 629                 }
 630                 goto turn_ss_off;
 631         }
 632
 633         if (slot == 2) {
 634                 if (regs->cr_iip == bundle_addr + 0x10) {
 635                         regs->cr_iip = resume_addr + 0x10;
 636                 }
 637         } else {
 638                 if (regs->cr_iip == bundle_addr) {
 639                         regs->cr_iip = resume_addr;
 640                 }
 641         }
 642
 643 turn_ss_off:
 644         /* Turn off Single Step bit */
 645         ia64_psr(regs)->ss = 0;
 646 }
 647
 648 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
 649 {
 650         unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
 651         unsigned long slot = (unsigned long)p->addr & 0xf;
 652
 653         /* single step inline if break instruction */
 654         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
 655                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
 656         else
 657                 regs->cr_iip = bundle_addr & ~0xFULL;
 658
 659         if (slot > 2)
 660                 slot = 0;
 661
 662         ia64_psr(regs)->ri = slot;
 663
 664         /* turn on single stepping */
 665         ia64_psr(regs)->ss = 1;
 666 }
 667
 668 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
 669 {
 670         unsigned int slot = ia64_psr(regs)->ri;
 671         unsigned int template, major_opcode;
 672         unsigned long kprobe_inst;
 673         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
 674         bundle_t bundle;
 675
 676         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
 677         template = bundle.quad0.template;
 678
 679         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 680         if (slot == 1 && bundle_encoding[template][1] == L)
 681                 slot++;
 682
 683         /* Get Kprobe probe instruction at given slot*/
 684         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
 685
 686         /* For break instruction,
 687          * Bits 37:40 Major opcode to be zero
 688          * Bits 27:32 X6 to be zero
 689          * Bits 32:35 X3 to be zero
 690          */
 691         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
 692                 /* Not a break instruction */
 693                 return 0;
 694         }
 695
 696         /* Is a break instruction */
 697         return 1;
 698 }
 699
 700 static int __kprobes pre_kprobes_handler(struct die_args *args)
 701 {
 702         struct kprobe *p;
 703         int ret = 0;
 704         struct pt_regs *regs = args->regs;
 705         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 706         struct kprobe_ctlblk *kcb;
 707
 708         /*
 709          * We don't want to be preempted for the entire
 710          * duration of kprobe processing
 711          */
 712         preempt_disable();
 713         kcb = get_kprobe_ctlblk();
 714
 715         /* Handle recursion cases */
 716         if (kprobe_running()) {
 717                 p = get_kprobe(addr);
 718                 if (p) {
 719                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
 720                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
 721                                 ia64_psr(regs)->ss = 0;
 722                                 goto no_kprobe;
 723                         }
 724                         /* We have reentered the pre_kprobe_handler(), since
 725                          * another probe was hit while within the handler.
 726                          * We here save the original kprobes variables and
 727                          * just single step on the instruction of the new probe
 728                          * without calling any user handlers.
 729                          */
 730                         save_previous_kprobe(kcb);
 731                         set_current_kprobe(p, kcb);
 732                         kprobes_inc_nmissed_count(p);
 733                         prepare_ss(p, regs);
 734                         kcb->kprobe_status = KPROBE_REENTER;
 735                         return 1;
 736                 } else if (args->err == __IA64_BREAK_JPROBE) {
 737                         /*
 738                          * jprobe instrumented function just completed
 739                          */
 740                         p = __get_cpu_var(current_kprobe);
 741                         if (p->break_handler && p->break_handler(p, regs)) {
 742                                 goto ss_probe;
 743                         }
 744                 } else if (!is_ia64_break_inst(regs)) {
 745                         /* The breakpoint instruction was removed by
 746                          * another cpu right after we hit, no further
 747                          * handling of this interrupt is appropriate
 748                          */
 749                         ret = 1;
 750                         goto no_kprobe;
 751                 } else {
 752                         /* Not our break */
 753                         goto no_kprobe;
 754                 }
 755         }
 756
 757         p = get_kprobe(addr);
 758         if (!p) {
 759                 if (!is_ia64_break_inst(regs)) {
 760                         /*
 761                          * The breakpoint instruction was removed right
 762                          * after we hit it.  Another cpu has removed
 763                          * either a probepoint or a debugger breakpoint
 764                          * at this address.  In either case, no further
 765                          * handling of this interrupt is appropriate.
 766                          */
 767                         ret = 1;
 768
 769                 }
 770
 771                 /* Not one of our break, let kernel handle it */
 772                 goto no_kprobe;
 773         }
 774
 775         set_current_kprobe(p, kcb);
 776         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 777
 778         if (p->pre_handler && p->pre_handler(p, regs))
 779                 /*
 780                  * Our pre-handler is specifically requesting that we just
 781                  * do a return.  This is used for both the jprobe pre-handler
 782                  * and the kretprobe trampoline
 783                  */
 784                 return 1;
 785
 786 ss_probe:
 787         prepare_ss(p, regs);
 788         kcb->kprobe_status = KPROBE_HIT_SS;
 789         return 1;
 790
 791 no_kprobe:
 792         preempt_enable_no_resched();
 793         return ret;
 794 }
 795
 796 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
 797 {
 798         struct kprobe *cur = kprobe_running();
 799         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 800
 801         if (!cur)
 802                 return 0;
 803
 804         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 805                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 806                 cur->post_handler(cur, regs, 0);
 807         }
 808
 809         resume_execution(cur, regs);
 810
 811         /*Restore back the original saved kprobes variables and continue. */
 812         if (kcb->kprobe_status == KPROBE_REENTER) {
 813                 restore_previous_kprobe(kcb);
 814                 goto out;
 815         }
 816         reset_current_kprobe();
 817
 818 out:
 819         preempt_enable_no_resched();
 820         return 1;
 821 }
 822
 823 int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 824 {
 825         struct kprobe *cur = kprobe_running();
 826         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 827
 828
 829         switch(kcb->kprobe_status) {
 830         case KPROBE_HIT_SS:
 831         case KPROBE_REENTER:
 832                 /*
 833                  * We are here because the instruction being single
 834                  * stepped caused a page fault. We reset the current
 835                  * kprobe and the instruction pointer points back to
 836                  * the probe address and allow the page fault handler
 837                  * to continue as a normal page fault.
 838                  */
 839                 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
 840                 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
 841                 if (kcb->kprobe_status == KPROBE_REENTER)
 842                         restore_previous_kprobe(kcb);
 843                 else
 844                         reset_current_kprobe();
 845                 preempt_enable_no_resched();
 846                 break;
 847         case KPROBE_HIT_ACTIVE:
 848         case KPROBE_HIT_SSDONE:
 849                 /*
 850                  * We increment the nmissed count for accounting,
 851                  * we can also use npre/npostfault count for accouting
 852                  * these specific fault cases.
 853                  */
 854                 kprobes_inc_nmissed_count(cur);
 855
 856                 /*
 857                  * We come here because instructions in the pre/post
 858                  * handler caused the page_fault, this could happen
 859                  * if handler tries to access user space by
 860                  * copy_from_user(), get_user() etc. Let the
 861                  * user-specified handler try to fix it first.
 862                  */
 863                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 864                         return 1;
 865                 /*
 866                  * In case the user-specified fault handler returned
 867                  * zero, try to fix up.
 868                  */
 869                 if (ia64_done_with_exception(regs))
 870                         return 1;
 871
 872                 /*
 873                  * Let ia64_do_page_fault() fix it.
 874                  */
 875                 break;
 876         default:
 877                 break;
 878         }
 879
 880         return 0;
 881 }
 882
 883 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 884                                        unsigned long val, void *data)
 885 {
 886         struct die_args *args = (struct die_args *)data;
 887         int ret = NOTIFY_DONE;
 888
 889         if (args->regs && user_mode(args->regs))
 890                 return ret;
 891
 892         switch(val) {
 893         case DIE_BREAK:
 894                 /* err is break number from ia64_bad_break() */
 895                 if ((args->err >> 12) == (__IA64_BREAK_KPROBE >> 12)
 896                         || args->err == __IA64_BREAK_JPROBE
 897                         || args->err == 0)
 898                         if (pre_kprobes_handler(args))
 899                                 ret = NOTIFY_STOP;
 900                 break;
 901         case DIE_FAULT:
 902                 /* err is vector number from ia64_fault() */
 903                 if (args->err == 36)
 904                         if (post_kprobes_handler(args->regs))
 905                                 ret = NOTIFY_STOP;
 906                 break;
 907         default:
 908                 break;
 909         }
 910         return ret;
 911 }
 912
 913 struct param_bsp_cfm {
 914         unsigned long ip;
 915         unsigned long *bsp;
 916         unsigned long cfm;
 917 };
 918
 919 static void ia64_get_bsp_cfm(struct unw_frame_info *info, void *arg)
 920 {
 921         unsigned long ip;
 922         struct param_bsp_cfm *lp = arg;
 923
 924         do {
 925                 unw_get_ip(info, &ip);
 926                 if (ip == 0)
 927                         break;
 928                 if (ip == lp->ip) {
 929                         unw_get_bsp(info, (unsigned long*)&lp->bsp);
 930                         unw_get_cfm(info, (unsigned long*)&lp->cfm);
 931                         return;
 932                 }
 933         } while (unw_unwind(info) >= 0);
 934         lp->bsp = NULL;
 935         lp->cfm = 0;
 936         return;
 937 }
 938
 939 unsigned long arch_deref_entry_point(void *entry)
 940 {
 941         return ((struct fnptr *)entry)->ip;
 942 }
 943
 944 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 945 {
 946         struct jprobe *jp = container_of(p, struct jprobe, kp);
 947         unsigned long addr = arch_deref_entry_point(jp->entry);
 948         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 949         struct param_bsp_cfm pa;
 950         int bytes;
 951
 952         /*
 953          * Callee owns the argument space and could overwrite it, eg
 954          * tail call optimization. So to be absolutely safe
 955          * we save the argument space before transferring the control
 956          * to instrumented jprobe function which runs in
 957          * the process context
 958          */
 959         pa.ip = regs->cr_iip;
 960         unw_init_running(ia64_get_bsp_cfm, &pa);
 961         bytes = (char *)ia64_rse_skip_regs(pa.bsp, pa.cfm & 0x3f)
 962                                 - (char *)pa.bsp;
 963         memcpy( kcb->jprobes_saved_stacked_regs,
 964                 pa.bsp,
 965                 bytes );
 966         kcb->bsp = pa.bsp;
 967         kcb->cfm = pa.cfm;
 968
 969         /* save architectural state */
 970         kcb->jprobe_saved_regs = *regs;
 971
 972         /* after rfi, execute the jprobe instrumented function */
 973         regs->cr_iip = addr & ~0xFULL;
 974         ia64_psr(regs)->ri = addr & 0xf;
 975         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 976
 977         /*
 978          * fix the return address to our jprobe_inst_return() function
 979          * in the jprobes.S file
 980          */
 981         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 982
 983         return 1;
 984 }
 985
 986 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 987 {
 988         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 989         int bytes;
 990
 991         /* restoring architectural state */
 992         *regs = kcb->jprobe_saved_regs;
 993
 994         /* restoring the original argument space */
 995         flush_register_stack();
 996         bytes = (char *)ia64_rse_skip_regs(kcb->bsp, kcb->cfm & 0x3f)
 997                                 - (char *)kcb->bsp;
 998         memcpy( kcb->bsp,
 999                 kcb->jprobes_saved_stacked_regs,
1000                 bytes );
1001         invalidate_stacked_regs();
1002
1003         preempt_enable_no_resched();
1004         return 1;
1005 }
1006
1007 static struct kprobe trampoline_p = {
1008         .pre_handler = trampoline_probe_handler
1009 };
1010
1011 int __init arch_init_kprobes(void)
1012 {
1013         trampoline_p.addr =
1014                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
1015         return register_kprobe(&trampoline_p);
1016 }
1017
1018 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
1019 {
1020         if (p->addr ==
1021                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip)
1022                 return 1;
1023
1024         return 0;
1025 }