arch/ia64/kernel/kprobes.c

   1 /*
   2  *  Kernel Probes (KProbes)
   3  *  arch/ia64/kernel/kprobes.c
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  *
  19  * Copyright (C) IBM Corporation, 2002, 2004
  20  * Copyright (C) Intel Corporation, 2005
  21  *
  22  * 2005-Apr     Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
  23  *              <anil.s.keshavamurthy@intel.com> adapted from i386
  24  */
  25
  26 #include <linux/config.h>
  27 #include <linux/kprobes.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/string.h>
  30 #include <linux/slab.h>
  31 #include <linux/preempt.h>
  32 #include <linux/moduleloader.h>
  33
  34 #include <asm/pgtable.h>
  35 #include <asm/kdebug.h>
  36 #include <asm/sections.h>
  37 #include <asm/uaccess.h>
  38
  39 extern void jprobe_inst_return(void);
  40
  41 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
  42 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
  43
  44 enum instruction_type {A, I, M, F, B, L, X, u};
  45 static enum instruction_type bundle_encoding[32][3] = {
  46   { M, I, I },                          /* 00 */
  47   { M, I, I },                          /* 01 */
  48   { M, I, I },                          /* 02 */
  49   { M, I, I },                          /* 03 */
  50   { M, L, X },                          /* 04 */
  51   { M, L, X },                          /* 05 */
  52   { u, u, u },                          /* 06 */
  53   { u, u, u },                          /* 07 */
  54   { M, M, I },                          /* 08 */
  55   { M, M, I },                          /* 09 */
  56   { M, M, I },                          /* 0A */
  57   { M, M, I },                          /* 0B */
  58   { M, F, I },                          /* 0C */
  59   { M, F, I },                          /* 0D */
  60   { M, M, F },                          /* 0E */
  61   { M, M, F },                          /* 0F */
  62   { M, I, B },                          /* 10 */
  63   { M, I, B },                          /* 11 */
  64   { M, B, B },                          /* 12 */
  65   { M, B, B },                          /* 13 */
  66   { u, u, u },                          /* 14 */
  67   { u, u, u },                          /* 15 */
  68   { B, B, B },                          /* 16 */
  69   { B, B, B },                          /* 17 */
  70   { M, M, B },                          /* 18 */
  71   { M, M, B },                          /* 19 */
  72   { u, u, u },                          /* 1A */
  73   { u, u, u },                          /* 1B */
  74   { M, F, B },                          /* 1C */
  75   { M, F, B },                          /* 1D */
  76   { u, u, u },                          /* 1E */
  77   { u, u, u },                          /* 1F */
  78 };
  79
  80 /*
  81  * In this function we check to see if the instruction
  82  * is IP relative instruction and update the kprobe
  83  * inst flag accordingly
  84  */
  85 static void __kprobes update_kprobe_inst_flag(uint template, uint  slot,
  86                                               uint major_opcode,
  87                                               unsigned long kprobe_inst,
  88                                               struct kprobe *p)
  89 {
  90         p->ainsn.inst_flag = 0;
  91         p->ainsn.target_br_reg = 0;
  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  * on which we are inserting kprobe is supported.
 134  * Returns 0 if supported
 135  * Returns -EINVAL if unsupported
 136  */
 137 static int __kprobes unsupported_inst(uint template, uint  slot,
 138                                       uint major_opcode,
 139                                       unsigned long kprobe_inst,
 140                                       struct kprobe *p)
 141 {
 142         unsigned long addr = (unsigned long)p->addr;
 143
 144         if (bundle_encoding[template][slot] == I) {
 145                 switch (major_opcode) {
 146                         case 0x0: //I_UNIT_MISC_OPCODE:
 147                         /*
 148                          * Check for Integer speculation instruction
 149                          * - Bit 33-35 to be equal to 0x1
 150                          */
 151                         if (((kprobe_inst >> 33) & 0x7) == 1) {
 152                                 printk(KERN_WARNING
 153                                         "Kprobes on speculation inst at <0x%lx> not supported\n",
 154                                         addr);
 155                                 return -EINVAL;
 156                         }
 157
 158                         /*
 159                          * IP relative mov instruction
 160                          *  - Bit 27-35 to be equal to 0x30
 161                          */
 162                         if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
 163                                 printk(KERN_WARNING
 164                                         "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
 165                                         addr);
 166                                 return -EINVAL;
 167
 168                         }
 169                 }
 170         }
 171         return 0;
 172 }
 173
 174
 175 /*
 176  * In this function we check to see if the instruction
 177  * (qp) cmpx.crel.ctype p1,p2=r2,r3
 178  * on which we are inserting kprobe is cmp instruction
 179  * with ctype as unc.
 180  */
 181 static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
 182                                             uint major_opcode,
 183                                             unsigned long kprobe_inst)
 184 {
 185         cmp_inst_t cmp_inst;
 186         uint ctype_unc = 0;
 187
 188         if (!((bundle_encoding[template][slot] == I) ||
 189                 (bundle_encoding[template][slot] == M)))
 190                 goto out;
 191
 192         if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
 193                 (major_opcode == 0xE)))
 194                 goto out;
 195
 196         cmp_inst.l = kprobe_inst;
 197         if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
 198                 /* Integere compare - Register Register (A6 type)*/
 199                 if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
 200                                 &&(cmp_inst.f.c == 1))
 201                         ctype_unc = 1;
 202         } else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
 203                 /* Integere compare - Immediate Register (A8 type)*/
 204                 if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
 205                         ctype_unc = 1;
 206         }
 207 out:
 208         return ctype_unc;
 209 }
 210
 211 /*
 212  * In this function we override the bundle with
 213  * the break instruction at the given slot.
 214  */
 215 static void __kprobes prepare_break_inst(uint template, uint  slot,
 216                                          uint major_opcode,
 217                                          unsigned long kprobe_inst,
 218                                          struct kprobe *p)
 219 {
 220         unsigned long break_inst = BREAK_INST;
 221         bundle_t *bundle = &p->ainsn.insn.bundle;
 222
 223         /*
 224          * Copy the original kprobe_inst qualifying predicate(qp)
 225          * to the break instruction iff !is_cmp_ctype_unc_inst
 226          * because for cmp instruction with ctype equal to unc,
 227          * which is a special instruction always needs to be
 228          * executed regradless of qp
 229          */
 230         if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
 231                 break_inst |= (0x3f & kprobe_inst);
 232
 233         switch (slot) {
 234           case 0:
 235                 bundle->quad0.slot0 = break_inst;
 236                 break;
 237           case 1:
 238                 bundle->quad0.slot1_p0 = break_inst;
 239                 bundle->quad1.slot1_p1 = break_inst >> (64-46);
 240                 break;
 241           case 2:
 242                 bundle->quad1.slot2 = break_inst;
 243                 break;
 244         }
 245
 246         /*
 247          * Update the instruction flag, so that we can
 248          * emulate the instruction properly after we
 249          * single step on original instruction
 250          */
 251         update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
 252 }
 253
 254 static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
 255                 unsigned long *kprobe_inst, uint *major_opcode)
 256 {
 257         unsigned long kprobe_inst_p0, kprobe_inst_p1;
 258         unsigned int template;
 259
 260         template = bundle->quad0.template;
 261
 262         switch (slot) {
 263           case 0:
 264                 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
 265                 *kprobe_inst = bundle->quad0.slot0;
 266                 break;
 267           case 1:
 268                 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
 269                 kprobe_inst_p0 = bundle->quad0.slot1_p0;
 270                 kprobe_inst_p1 = bundle->quad1.slot1_p1;
 271                 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
 272                 break;
 273           case 2:
 274                 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
 275                 *kprobe_inst = bundle->quad1.slot2;
 276                 break;
 277         }
 278 }
 279
 280 /* Returns non-zero if the addr is in the Interrupt Vector Table */
 281 static int __kprobes in_ivt_functions(unsigned long addr)
 282 {
 283         return (addr >= (unsigned long)__start_ivt_text
 284                 && addr < (unsigned long)__end_ivt_text);
 285 }
 286
 287 static int __kprobes valid_kprobe_addr(int template, int slot,
 288                                        unsigned long addr)
 289 {
 290         if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
 291                 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
 292                                 "at 0x%lx\n", addr);
 293                 return -EINVAL;
 294         }
 295
 296         if (in_ivt_functions(addr)) {
 297                 printk(KERN_WARNING "Kprobes can't be inserted inside "
 298                                 "IVT functions at 0x%lx\n", addr);
 299                 return -EINVAL;
 300         }
 301
 302         if (slot == 1 && bundle_encoding[template][1] != L) {
 303                 printk(KERN_WARNING "Inserting kprobes on slot #1 "
 304                        "is not supported\n");
 305                 return -EINVAL;
 306         }
 307
 308         return 0;
 309 }
 310
 311 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 312 {
 313         kcb->prev_kprobe.kp = kprobe_running();
 314         kcb->prev_kprobe.status = kcb->kprobe_status;
 315 }
 316
 317 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 318 {
 319         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 320         kcb->kprobe_status = kcb->prev_kprobe.status;
 321 }
 322
 323 static void __kprobes set_current_kprobe(struct kprobe *p,
 324                         struct kprobe_ctlblk *kcb)
 325 {
 326         __get_cpu_var(current_kprobe) = p;
 327 }
 328
 329 static void kretprobe_trampoline(void)
 330 {
 331 }
 332
 333 /*
 334  * At this point the target function has been tricked into
 335  * returning into our trampoline.  Lookup the associated instance
 336  * and then:
 337  *    - call the handler function
 338  *    - cleanup by marking the instance as unused
 339  *    - long jump back to the original return address
 340  */
 341 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 342 {
 343         struct kretprobe_instance *ri = NULL;
 344         struct hlist_head *head;
 345         struct hlist_node *node, *tmp;
 346         unsigned long flags, orig_ret_address = 0;
 347         unsigned long trampoline_address =
 348                 ((struct fnptr *)kretprobe_trampoline)->ip;
 349
 350         spin_lock_irqsave(&kretprobe_lock, flags);
 351         head = kretprobe_inst_table_head(current);
 352
 353         /*
 354          * It is possible to have multiple instances associated with a given
 355          * task either because an multiple functions in the call path
 356          * have a return probe installed on them, and/or more then one return
 357          * return probe was registered for a target function.
 358          *
 359          * We can handle this because:
 360          *     - instances are always inserted at the head of the list
 361          *     - when multiple return probes are registered for the same
 362          *       function, the first instance's ret_addr will point to the
 363          *       real return address, and all the rest will point to
 364          *       kretprobe_trampoline
 365          */
 366         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 367                 if (ri->task != current)
 368                         /* another task is sharing our hash bucket */
 369                         continue;
 370
 371                 if (ri->rp && ri->rp->handler)
 372                         ri->rp->handler(ri, regs);
 373
 374                 orig_ret_address = (unsigned long)ri->ret_addr;
 375                 recycle_rp_inst(ri);
 376
 377                 if (orig_ret_address != trampoline_address)
 378                         /*
 379                          * This is the real return address. Any other
 380                          * instances associated with this task are for
 381                          * other calls deeper on the call stack
 382                          */
 383                         break;
 384         }
 385
 386         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 387         regs->cr_iip = orig_ret_address;
 388
 389         reset_current_kprobe();
 390         spin_unlock_irqrestore(&kretprobe_lock, flags);
 391         preempt_enable_no_resched();
 392
 393         /*
 394          * By returning a non-zero value, we are telling
 395          * kprobe_handler() that we don't want the post_handler
 396          * to run (and have re-enabled preemption)
 397          */
 398         return 1;
 399 }
 400
 401 /* Called with kretprobe_lock held */
 402 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
 403                                       struct pt_regs *regs)
 404 {
 405         struct kretprobe_instance *ri;
 406
 407         if ((ri = get_free_rp_inst(rp)) != NULL) {
 408                 ri->rp = rp;
 409                 ri->task = current;
 410                 ri->ret_addr = (kprobe_opcode_t *)regs->b0;
 411
 412                 /* Replace the return addr with trampoline addr */
 413                 regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
 414
 415                 add_rp_inst(ri);
 416         } else {
 417                 rp->nmissed++;
 418         }
 419 }
 420
 421 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 422 {
 423         unsigned long addr = (unsigned long) p->addr;
 424         unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
 425         unsigned long kprobe_inst=0;
 426         unsigned int slot = addr & 0xf, template, major_opcode = 0;
 427         bundle_t *bundle = &p->ainsn.insn.bundle;
 428
 429         memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
 430         memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));
 431
 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, p))
 445                         return -EINVAL;
 446
 447         prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
 448
 449         return 0;
 450 }
 451
 452 void __kprobes arch_arm_kprobe(struct kprobe *p)
 453 {
 454         unsigned long addr = (unsigned long)p->addr;
 455         unsigned long arm_addr = addr & ~0xFULL;
 456
 457         memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
 458         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 459 }
 460
 461 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 462 {
 463         unsigned long addr = (unsigned long)p->addr;
 464         unsigned long arm_addr = addr & ~0xFULL;
 465
 466         /* p->opcode contains the original unaltered bundle */
 467         memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
 468         flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
 469 }
 470
 471 /*
 472  * We are resuming execution after a single step fault, so the pt_regs
 473  * structure reflects the register state after we executed the instruction
 474  * located in the kprobe (p->ainsn.insn.bundle).  We still need to adjust
 475  * the ip to point back to the original stack address. To set the IP address
 476  * to original stack address, handle the case where we need to fixup the
 477  * relative IP address and/or fixup branch register.
 478  */
 479 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 480 {
 481         unsigned long bundle_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
 482         unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
 483         unsigned long template;
 484         int slot = ((unsigned long)p->addr & 0xf);
 485
 486         template = p->opcode.bundle.quad0.template;
 487
 488         if (slot == 1 && bundle_encoding[template][1] == L)
 489                 slot = 2;
 490
 491         if (p->ainsn.inst_flag) {
 492
 493                 if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
 494                         /* Fix relative IP address */
 495                         regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
 496                 }
 497
 498                 if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
 499                 /*
 500                  * Fix target branch register, software convention is
 501                  * to use either b0 or b6 or b7, so just checking
 502                  * only those registers
 503                  */
 504                         switch (p->ainsn.target_br_reg) {
 505                         case 0:
 506                                 if ((regs->b0 == bundle_addr) ||
 507                                         (regs->b0 == bundle_addr + 0x10)) {
 508                                         regs->b0 = (regs->b0 - bundle_addr) +
 509                                                 resume_addr;
 510                                 }
 511                                 break;
 512                         case 6:
 513                                 if ((regs->b6 == bundle_addr) ||
 514                                         (regs->b6 == bundle_addr + 0x10)) {
 515                                         regs->b6 = (regs->b6 - bundle_addr) +
 516                                                 resume_addr;
 517                                 }
 518                                 break;
 519                         case 7:
 520                                 if ((regs->b7 == bundle_addr) ||
 521                                         (regs->b7 == bundle_addr + 0x10)) {
 522                                         regs->b7 = (regs->b7 - bundle_addr) +
 523                                                 resume_addr;
 524                                 }
 525                                 break;
 526                         } /* end switch */
 527                 }
 528                 goto turn_ss_off;
 529         }
 530
 531         if (slot == 2) {
 532                 if (regs->cr_iip == bundle_addr + 0x10) {
 533                         regs->cr_iip = resume_addr + 0x10;
 534                 }
 535         } else {
 536                 if (regs->cr_iip == bundle_addr) {
 537                         regs->cr_iip = resume_addr;
 538                 }
 539         }
 540
 541 turn_ss_off:
 542         /* Turn off Single Step bit */
 543         ia64_psr(regs)->ss = 0;
 544 }
 545
 546 static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
 547 {
 548         unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
 549         unsigned long slot = (unsigned long)p->addr & 0xf;
 550
 551         /* single step inline if break instruction */
 552         if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
 553                 regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
 554         else
 555                 regs->cr_iip = bundle_addr & ~0xFULL;
 556
 557         if (slot > 2)
 558                 slot = 0;
 559
 560         ia64_psr(regs)->ri = slot;
 561
 562         /* turn on single stepping */
 563         ia64_psr(regs)->ss = 1;
 564 }
 565
 566 static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
 567 {
 568         unsigned int slot = ia64_psr(regs)->ri;
 569         unsigned int template, major_opcode;
 570         unsigned long kprobe_inst;
 571         unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
 572         bundle_t bundle;
 573
 574         memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
 575         template = bundle.quad0.template;
 576
 577         /* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
 578         if (slot == 1 && bundle_encoding[template][1] == L)
 579                 slot++;
 580
 581         /* Get Kprobe probe instruction at given slot*/
 582         get_kprobe_inst(&bundle, slot, &kprobe_inst, &major_opcode);
 583
 584         /* For break instruction,
 585          * Bits 37:40 Major opcode to be zero
 586          * Bits 27:32 X6 to be zero
 587          * Bits 32:35 X3 to be zero
 588          */
 589         if (major_opcode || ((kprobe_inst >> 27) & 0x1FF) ) {
 590                 /* Not a break instruction */
 591                 return 0;
 592         }
 593
 594         /* Is a break instruction */
 595         return 1;
 596 }
 597
 598 static int __kprobes pre_kprobes_handler(struct die_args *args)
 599 {
 600         struct kprobe *p;
 601         int ret = 0;
 602         struct pt_regs *regs = args->regs;
 603         kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
 604         struct kprobe_ctlblk *kcb;
 605
 606         /*
 607          * We don't want to be preempted for the entire
 608          * duration of kprobe processing
 609          */
 610         preempt_disable();
 611         kcb = get_kprobe_ctlblk();
 612
 613         /* Handle recursion cases */
 614         if (kprobe_running()) {
 615                 p = get_kprobe(addr);
 616                 if (p) {
 617                         if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
 618                              (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
 619                                 ia64_psr(regs)->ss = 0;
 620                                 goto no_kprobe;
 621                         }
 622                         /* We have reentered the pre_kprobe_handler(), since
 623                          * another probe was hit while within the handler.
 624                          * We here save the original kprobes variables and
 625                          * just single step on the instruction of the new probe
 626                          * without calling any user handlers.
 627                          */
 628                         save_previous_kprobe(kcb);
 629                         set_current_kprobe(p, kcb);
 630                         kprobes_inc_nmissed_count(p);
 631                         prepare_ss(p, regs);
 632                         kcb->kprobe_status = KPROBE_REENTER;
 633                         return 1;
 634                 } else if (args->err == __IA64_BREAK_JPROBE) {
 635                         /*
 636                          * jprobe instrumented function just completed
 637                          */
 638                         p = __get_cpu_var(current_kprobe);
 639                         if (p->break_handler && p->break_handler(p, regs)) {
 640                                 goto ss_probe;
 641                         }
 642                 } else if (!is_ia64_break_inst(regs)) {
 643                         /* The breakpoint instruction was removed by
 644                          * another cpu right after we hit, no further
 645                          * handling of this interrupt is appropriate
 646                          */
 647                         ret = 1;
 648                         goto no_kprobe;
 649                 } else {
 650                         /* Not our break */
 651                         goto no_kprobe;
 652                 }
 653         }
 654
 655         p = get_kprobe(addr);
 656         if (!p) {
 657                 if (!is_ia64_break_inst(regs)) {
 658                         /*
 659                          * The breakpoint instruction was removed right
 660                          * after we hit it.  Another cpu has removed
 661                          * either a probepoint or a debugger breakpoint
 662                          * at this address.  In either case, no further
 663                          * handling of this interrupt is appropriate.
 664                          */
 665                         ret = 1;
 666
 667                 }
 668
 669                 /* Not one of our break, let kernel handle it */
 670                 goto no_kprobe;
 671         }
 672
 673         set_current_kprobe(p, kcb);
 674         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 675
 676         if (p->pre_handler && p->pre_handler(p, regs))
 677                 /*
 678                  * Our pre-handler is specifically requesting that we just
 679                  * do a return.  This is used for both the jprobe pre-handler
 680                  * and the kretprobe trampoline
 681                  */
 682                 return 1;
 683
 684 ss_probe:
 685         prepare_ss(p, regs);
 686         kcb->kprobe_status = KPROBE_HIT_SS;
 687         return 1;
 688
 689 no_kprobe:
 690         preempt_enable_no_resched();
 691         return ret;
 692 }
 693
 694 static int __kprobes post_kprobes_handler(struct pt_regs *regs)
 695 {
 696         struct kprobe *cur = kprobe_running();
 697         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 698
 699         if (!cur)
 700                 return 0;
 701
 702         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 703                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 704                 cur->post_handler(cur, regs, 0);
 705         }
 706
 707         resume_execution(cur, regs);
 708
 709         /*Restore back the original saved kprobes variables and continue. */
 710         if (kcb->kprobe_status == KPROBE_REENTER) {
 711                 restore_previous_kprobe(kcb);
 712                 goto out;
 713         }
 714         reset_current_kprobe();
 715
 716 out:
 717         preempt_enable_no_resched();
 718         return 1;
 719 }
 720
 721 static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 722 {
 723         struct kprobe *cur = kprobe_running();
 724         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 725
 726
 727         switch(kcb->kprobe_status) {
 728         case KPROBE_HIT_SS:
 729         case KPROBE_REENTER:
 730                 /*
 731                  * We are here because the instruction being single
 732                  * stepped caused a page fault. We reset the current
 733                  * kprobe and the instruction pointer points back to
 734                  * the probe address and allow the page fault handler
 735                  * to continue as a normal page fault.
 736                  */
 737                 regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
 738                 ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
 739                 if (kcb->kprobe_status == KPROBE_REENTER)
 740                         restore_previous_kprobe(kcb);
 741                 else
 742                         reset_current_kprobe();
 743                 preempt_enable_no_resched();
 744                 break;
 745         case KPROBE_HIT_ACTIVE:
 746         case KPROBE_HIT_SSDONE:
 747                 /*
 748                  * We increment the nmissed count for accounting,
 749                  * we can also use npre/npostfault count for accouting
 750                  * these specific fault cases.
 751                  */
 752                 kprobes_inc_nmissed_count(cur);
 753
 754                 /*
 755                  * We come here because instructions in the pre/post
 756                  * handler caused the page_fault, this could happen
 757                  * if handler tries to access user space by
 758                  * copy_from_user(), get_user() etc. Let the
 759                  * user-specified handler try to fix it first.
 760                  */
 761                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 762                         return 1;
 763
 764                 /*
 765                  * Let ia64_do_page_fault() fix it.
 766                  */
 767                 break;
 768         default:
 769                 break;
 770         }
 771
 772         return 0;
 773 }
 774
 775 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 776                                        unsigned long val, void *data)
 777 {
 778         struct die_args *args = (struct die_args *)data;
 779         int ret = NOTIFY_DONE;
 780
 781         if (args->regs && user_mode(args->regs))
 782                 return ret;
 783
 784         switch(val) {
 785         case DIE_BREAK:
 786                 /* err is break number from ia64_bad_break() */
 787                 if (args->err == 0x80200 || args->err == 0x80300 || args->err == 0)
 788                         if (pre_kprobes_handler(args))
 789                                 ret = NOTIFY_STOP;
 790                 break;
 791         case DIE_FAULT:
 792                 /* err is vector number from ia64_fault() */
 793                 if (args->err == 36)
 794                         if (post_kprobes_handler(args->regs))
 795                                 ret = NOTIFY_STOP;
 796                 break;
 797         case DIE_PAGE_FAULT:
 798                 /* kprobe_running() needs smp_processor_id() */
 799                 preempt_disable();
 800                 if (kprobe_running() &&
 801                         kprobes_fault_handler(args->regs, args->trapnr))
 802                         ret = NOTIFY_STOP;
 803                 preempt_enable();
 804         default:
 805                 break;
 806         }
 807         return ret;
 808 }
 809
 810 struct param_bsp_cfm {
 811         unsigned long ip;
 812         unsigned long *bsp;
 813         unsigned long cfm;
 814 };
 815
 816 static void ia64_get_bsp_cfm(struct unw_frame_info *info, void *arg)
 817 {
 818         unsigned long ip;
 819         struct param_bsp_cfm *lp = arg;
 820
 821         do {
 822                 unw_get_ip(info, &ip);
 823                 if (ip == 0)
 824                         break;
 825                 if (ip == lp->ip) {
 826                         unw_get_bsp(info, (unsigned long*)&lp->bsp);
 827                         unw_get_cfm(info, (unsigned long*)&lp->cfm);
 828                         return;
 829                 }
 830         } while (unw_unwind(info) >= 0);
 831         lp->bsp = 0;
 832         lp->cfm = 0;
 833         return;
 834 }
 835
 836 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 837 {
 838         struct jprobe *jp = container_of(p, struct jprobe, kp);
 839         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
 840         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 841         struct param_bsp_cfm pa;
 842         int bytes;
 843
 844         /*
 845          * Callee owns the argument space and could overwrite it, eg
 846          * tail call optimization. So to be absolutely safe
 847          * we save the argument space before transfering the control
 848          * to instrumented jprobe function which runs in
 849          * the process context
 850          */
 851         pa.ip = regs->cr_iip;
 852         unw_init_running(ia64_get_bsp_cfm, &pa);
 853         bytes = (char *)ia64_rse_skip_regs(pa.bsp, pa.cfm & 0x3f)
 854                                 - (char *)pa.bsp;
 855         memcpy( kcb->jprobes_saved_stacked_regs,
 856                 pa.bsp,
 857                 bytes );
 858         kcb->bsp = pa.bsp;
 859         kcb->cfm = pa.cfm;
 860
 861         /* save architectural state */
 862         kcb->jprobe_saved_regs = *regs;
 863
 864         /* after rfi, execute the jprobe instrumented function */
 865         regs->cr_iip = addr & ~0xFULL;
 866         ia64_psr(regs)->ri = addr & 0xf;
 867         regs->r1 = ((struct fnptr *)(jp->entry))->gp;
 868
 869         /*
 870          * fix the return address to our jprobe_inst_return() function
 871          * in the jprobes.S file
 872          */
 873         regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
 874
 875         return 1;
 876 }
 877
 878 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 879 {
 880         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 881         int bytes;
 882
 883         /* restoring architectural state */
 884         *regs = kcb->jprobe_saved_regs;
 885
 886         /* restoring the original argument space */
 887         flush_register_stack();
 888         bytes = (char *)ia64_rse_skip_regs(kcb->bsp, kcb->cfm & 0x3f)
 889                                 - (char *)kcb->bsp;
 890         memcpy( kcb->bsp,
 891                 kcb->jprobes_saved_stacked_regs,
 892                 bytes );
 893         invalidate_stacked_regs();
 894
 895         preempt_enable_no_resched();
 896         return 1;
 897 }
 898
 899 static struct kprobe trampoline_p = {
 900         .pre_handler = trampoline_probe_handler
 901 };
 902
 903 int __init arch_init_kprobes(void)
 904 {
 905         trampoline_p.addr =
 906                 (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
 907         return register_kprobe(&trampoline_p);
 908 }