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   1 /*
   2  *  Kernel Probes (KProbes)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2002, 2006
  19  *
  20  * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
  21  */
  22
  23 #include <linux/kprobes.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/preempt.h>
  26 #include <linux/stop_machine.h>
  27 #include <linux/kdebug.h>
  28 #include <linux/uaccess.h>
  29 #include <asm/cacheflush.h>
  30 #include <asm/sections.h>
  31 #include <linux/module.h>
  32 #include <linux/slab.h>
  33
  34 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
  35 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
  36
  37 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
  38
  39 int __kprobes arch_prepare_kprobe(struct kprobe *p)
  40 {
  41         /* Make sure the probe isn't going on a difficult instruction */
  42         if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
  43                 return -EINVAL;
  44
  45         if ((unsigned long)p->addr & 0x01)
  46                 return -EINVAL;
  47
  48         /* Use the get_insn_slot() facility for correctness */
  49         if (!(p->ainsn.insn = get_insn_slot()))
  50                 return -ENOMEM;
  51
  52         memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
  53
  54         get_instruction_type(&p->ainsn);
  55         p->opcode = *p->addr;
  56         return 0;
  57 }
  58
  59 int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
  60 {
  61         switch (*(__u8 *) instruction) {
  62         case 0x0c:      /* bassm */
  63         case 0x0b:      /* bsm   */
  64         case 0x83:      /* diag  */
  65         case 0x44:      /* ex    */
  66                 return -EINVAL;
  67         }
  68         switch (*(__u16 *) instruction) {
  69         case 0x0101:    /* pr    */
  70         case 0xb25a:    /* bsa   */
  71         case 0xb240:    /* bakr  */
  72         case 0xb258:    /* bsg   */
  73         case 0xb218:    /* pc    */
  74         case 0xb228:    /* pt    */
  75                 return -EINVAL;
  76         }
  77         return 0;
  78 }
  79
  80 void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
  81 {
  82         /* default fixup method */
  83         ainsn->fixup = FIXUP_PSW_NORMAL;
  84
  85         /* save r1 operand */
  86         ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
  87
  88         /* save the instruction length (pop 5-5) in bytes */
  89         switch (*(__u8 *) (ainsn->insn) >> 6) {
  90         case 0:
  91                 ainsn->ilen = 2;
  92                 break;
  93         case 1:
  94         case 2:
  95                 ainsn->ilen = 4;
  96                 break;
  97         case 3:
  98                 ainsn->ilen = 6;
  99                 break;
 100         }
 101
 102         switch (*(__u8 *) ainsn->insn) {
 103         case 0x05:      /* balr */
 104         case 0x0d:      /* basr */
 105                 ainsn->fixup = FIXUP_RETURN_REGISTER;
 106                 /* if r2 = 0, no branch will be taken */
 107                 if ((*ainsn->insn & 0x0f) == 0)
 108                         ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
 109                 break;
 110         case 0x06:      /* bctr */
 111         case 0x07:      /* bcr  */
 112                 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 113                 break;
 114         case 0x45:      /* bal  */
 115         case 0x4d:      /* bas  */
 116                 ainsn->fixup = FIXUP_RETURN_REGISTER;
 117                 break;
 118         case 0x47:      /* bc   */
 119         case 0x46:      /* bct  */
 120         case 0x86:      /* bxh  */
 121         case 0x87:      /* bxle */
 122                 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 123                 break;
 124         case 0x82:      /* lpsw */
 125                 ainsn->fixup = FIXUP_NOT_REQUIRED;
 126                 break;
 127         case 0xb2:      /* lpswe */
 128                 if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
 129                         ainsn->fixup = FIXUP_NOT_REQUIRED;
 130                 }
 131                 break;
 132         case 0xa7:      /* bras */
 133                 if ((*ainsn->insn & 0x0f) == 0x05) {
 134                         ainsn->fixup |= FIXUP_RETURN_REGISTER;
 135                 }
 136                 break;
 137         case 0xc0:
 138                 if ((*ainsn->insn & 0x0f) == 0x00  /* larl  */
 139                         || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
 140                 ainsn->fixup |= FIXUP_RETURN_REGISTER;
 141                 break;
 142         case 0xeb:
 143                 if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 ||   /* bxhg  */
 144                         *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
 145                         ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 146                 }
 147                 break;
 148         case 0xe3:      /* bctg */
 149                 if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
 150                         ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 151                 }
 152                 break;
 153         }
 154 }
 155
 156 static int __kprobes swap_instruction(void *aref)
 157 {
 158         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 159         unsigned long status = kcb->kprobe_status;
 160         struct ins_replace_args *args = aref;
 161         int rc;
 162
 163         kcb->kprobe_status = KPROBE_SWAP_INST;
 164         rc = probe_kernel_write(args->ptr, &args->new, sizeof(args->new));
 165         kcb->kprobe_status = status;
 166         return rc;
 167 }
 168
 169 void __kprobes arch_arm_kprobe(struct kprobe *p)
 170 {
 171         struct ins_replace_args args;
 172
 173         args.ptr = p->addr;
 174         args.old = p->opcode;
 175         args.new = BREAKPOINT_INSTRUCTION;
 176         stop_machine(swap_instruction, &args, NULL);
 177 }
 178
 179 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 180 {
 181         struct ins_replace_args args;
 182
 183         args.ptr = p->addr;
 184         args.old = BREAKPOINT_INSTRUCTION;
 185         args.new = p->opcode;
 186         stop_machine(swap_instruction, &args, NULL);
 187 }
 188
 189 void __kprobes arch_remove_kprobe(struct kprobe *p)
 190 {
 191         if (p->ainsn.insn) {
 192                 free_insn_slot(p->ainsn.insn, 0);
 193                 p->ainsn.insn = NULL;
 194         }
 195 }
 196
 197 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 198 {
 199         per_cr_bits kprobe_per_regs[1];
 200
 201         memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
 202         regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
 203
 204         /* Set up the per control reg info, will pass to lctl */
 205         kprobe_per_regs[0].em_instruction_fetch = 1;
 206         kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
 207         kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
 208
 209         /* Set the PER control regs, turns on single step for this address */
 210         __ctl_load(kprobe_per_regs, 9, 11);
 211         regs->psw.mask |= PSW_MASK_PER;
 212         regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
 213 }
 214
 215 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 216 {
 217         kcb->prev_kprobe.kp = kprobe_running();
 218         kcb->prev_kprobe.status = kcb->kprobe_status;
 219         kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
 220         memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
 221                                         sizeof(kcb->kprobe_saved_ctl));
 222 }
 223
 224 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 225 {
 226         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 227         kcb->kprobe_status = kcb->prev_kprobe.status;
 228         kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
 229         memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
 230                                         sizeof(kcb->kprobe_saved_ctl));
 231 }
 232
 233 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 234                                                 struct kprobe_ctlblk *kcb)
 235 {
 236         __get_cpu_var(current_kprobe) = p;
 237         /* Save the interrupt and per flags */
 238         kcb->kprobe_saved_imask = regs->psw.mask &
 239             (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
 240         /* Save the control regs that govern PER */
 241         __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
 242 }
 243
 244 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 245                                         struct pt_regs *regs)
 246 {
 247         ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
 248
 249         /* Replace the return addr with trampoline addr */
 250         regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
 251 }
 252
 253 static int __kprobes kprobe_handler(struct pt_regs *regs)
 254 {
 255         struct kprobe *p;
 256         int ret = 0;
 257         unsigned long *addr = (unsigned long *)
 258                 ((regs->psw.addr & PSW_ADDR_INSN) - 2);
 259         struct kprobe_ctlblk *kcb;
 260
 261         /*
 262          * We don't want to be preempted for the entire
 263          * duration of kprobe processing
 264          */
 265         preempt_disable();
 266         kcb = get_kprobe_ctlblk();
 267
 268         /* Check we're not actually recursing */
 269         if (kprobe_running()) {
 270                 p = get_kprobe(addr);
 271                 if (p) {
 272                         if (kcb->kprobe_status == KPROBE_HIT_SS &&
 273                             *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
 274                                 regs->psw.mask &= ~PSW_MASK_PER;
 275                                 regs->psw.mask |= kcb->kprobe_saved_imask;
 276                                 goto no_kprobe;
 277                         }
 278                         /* We have reentered the kprobe_handler(), since
 279                          * another probe was hit while within the handler.
 280                          * We here save the original kprobes variables and
 281                          * just single step on the instruction of the new probe
 282                          * without calling any user handlers.
 283                          */
 284                         save_previous_kprobe(kcb);
 285                         set_current_kprobe(p, regs, kcb);
 286                         kprobes_inc_nmissed_count(p);
 287                         prepare_singlestep(p, regs);
 288                         kcb->kprobe_status = KPROBE_REENTER;
 289                         return 1;
 290                 } else {
 291                         p = __get_cpu_var(current_kprobe);
 292                         if (p->break_handler && p->break_handler(p, regs)) {
 293                                 goto ss_probe;
 294                         }
 295                 }
 296                 goto no_kprobe;
 297         }
 298
 299         p = get_kprobe(addr);
 300         if (!p)
 301                 /*
 302                  * No kprobe at this address. The fault has not been
 303                  * caused by a kprobe breakpoint. The race of breakpoint
 304                  * vs. kprobe remove does not exist because on s390 we
 305                  * use stop_machine to arm/disarm the breakpoints.
 306                  */
 307                 goto no_kprobe;
 308
 309         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 310         set_current_kprobe(p, regs, kcb);
 311         if (p->pre_handler && p->pre_handler(p, regs))
 312                 /* handler has already set things up, so skip ss setup */
 313                 return 1;
 314
 315 ss_probe:
 316         prepare_singlestep(p, regs);
 317         kcb->kprobe_status = KPROBE_HIT_SS;
 318         return 1;
 319
 320 no_kprobe:
 321         preempt_enable_no_resched();
 322         return ret;
 323 }
 324
 325 /*
 326  * Function return probe trampoline:
 327  *      - init_kprobes() establishes a probepoint here
 328  *      - When the probed function returns, this probe
 329  *              causes the handlers to fire
 330  */
 331 static void __used kretprobe_trampoline_holder(void)
 332 {
 333         asm volatile(".global kretprobe_trampoline\n"
 334                      "kretprobe_trampoline: bcr 0,0\n");
 335 }
 336
 337 /*
 338  * Called when the probe at kretprobe trampoline is hit
 339  */
 340 static int __kprobes trampoline_probe_handler(struct kprobe *p,
 341                                               struct pt_regs *regs)
 342 {
 343         struct kretprobe_instance *ri = NULL;
 344         struct hlist_head *head, empty_rp;
 345         struct hlist_node *node, *tmp;
 346         unsigned long flags, orig_ret_address = 0;
 347         unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
 348
 349         INIT_HLIST_HEAD(&empty_rp);
 350         kretprobe_hash_lock(current, &head, &flags);
 351
 352         /*
 353          * It is possible to have multiple instances associated with a given
 354          * task either because an multiple functions in the call path
 355          * have a return probe installed on them, and/or more than one return
 356          * return probe was registered for a target function.
 357          *
 358          * We can handle this because:
 359          *     - instances are always inserted at the head of the list
 360          *     - when multiple return probes are registered for the same
 361          *       function, the first instance's ret_addr will point to the
 362          *       real return address, and all the rest will point to
 363          *       kretprobe_trampoline
 364          */
 365         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 366                 if (ri->task != current)
 367                         /* another task is sharing our hash bucket */
 368                         continue;
 369
 370                 if (ri->rp && ri->rp->handler)
 371                         ri->rp->handler(ri, regs);
 372
 373                 orig_ret_address = (unsigned long)ri->ret_addr;
 374                 recycle_rp_inst(ri, &empty_rp);
 375
 376                 if (orig_ret_address != trampoline_address) {
 377                         /*
 378                          * This is the real return address. Any other
 379                          * instances associated with this task are for
 380                          * other calls deeper on the call stack
 381                          */
 382                         break;
 383                 }
 384         }
 385         kretprobe_assert(ri, orig_ret_address, trampoline_address);
 386         regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
 387
 388         reset_current_kprobe();
 389         kretprobe_hash_unlock(current, &flags);
 390         preempt_enable_no_resched();
 391
 392         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 393                 hlist_del(&ri->hlist);
 394                 kfree(ri);
 395         }
 396         /*
 397          * By returning a non-zero value, we are telling
 398          * kprobe_handler() that we don't want the post_handler
 399          * to run (and have re-enabled preemption)
 400          */
 401         return 1;
 402 }
 403
 404 /*
 405  * Called after single-stepping.  p->addr is the address of the
 406  * instruction whose first byte has been replaced by the "breakpoint"
 407  * instruction.  To avoid the SMP problems that can occur when we
 408  * temporarily put back the original opcode to single-step, we
 409  * single-stepped a copy of the instruction.  The address of this
 410  * copy is p->ainsn.insn.
 411  */
 412 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 413 {
 414         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 415
 416         regs->psw.addr &= PSW_ADDR_INSN;
 417
 418         if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
 419                 regs->psw.addr = (unsigned long)p->addr +
 420                                 ((unsigned long)regs->psw.addr -
 421                                  (unsigned long)p->ainsn.insn);
 422
 423         if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
 424                 if ((unsigned long)regs->psw.addr -
 425                     (unsigned long)p->ainsn.insn == p->ainsn.ilen)
 426                         regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
 427
 428         if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
 429                 regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
 430                                                 (regs->gprs[p->ainsn.reg] -
 431                                                 (unsigned long)p->ainsn.insn))
 432                                                 | PSW_ADDR_AMODE;
 433
 434         regs->psw.addr |= PSW_ADDR_AMODE;
 435         /* turn off PER mode */
 436         regs->psw.mask &= ~PSW_MASK_PER;
 437         /* Restore the original per control regs */
 438         __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
 439         regs->psw.mask |= kcb->kprobe_saved_imask;
 440 }
 441
 442 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
 443 {
 444         struct kprobe *cur = kprobe_running();
 445         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 446
 447         if (!cur)
 448                 return 0;
 449
 450         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 451                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 452                 cur->post_handler(cur, regs, 0);
 453         }
 454
 455         resume_execution(cur, regs);
 456
 457         /*Restore back the original saved kprobes variables and continue. */
 458         if (kcb->kprobe_status == KPROBE_REENTER) {
 459                 restore_previous_kprobe(kcb);
 460                 goto out;
 461         }
 462         reset_current_kprobe();
 463 out:
 464         preempt_enable_no_resched();
 465
 466         /*
 467          * if somebody else is singlestepping across a probe point, psw mask
 468          * will have PER set, in which case, continue the remaining processing
 469          * of do_single_step, as if this is not a probe hit.
 470          */
 471         if (regs->psw.mask & PSW_MASK_PER) {
 472                 return 0;
 473         }
 474
 475         return 1;
 476 }
 477
 478 int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 479 {
 480         struct kprobe *cur = kprobe_running();
 481         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 482         const struct exception_table_entry *entry;
 483
 484         switch(kcb->kprobe_status) {
 485         case KPROBE_SWAP_INST:
 486                 /* We are here because the instruction replacement failed */
 487                 return 0;
 488         case KPROBE_HIT_SS:
 489         case KPROBE_REENTER:
 490                 /*
 491                  * We are here because the instruction being single
 492                  * stepped caused a page fault. We reset the current
 493                  * kprobe and the nip points back to the probe address
 494                  * and allow the page fault handler to continue as a
 495                  * normal page fault.
 496                  */
 497                 regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
 498                 regs->psw.mask &= ~PSW_MASK_PER;
 499                 regs->psw.mask |= kcb->kprobe_saved_imask;
 500                 if (kcb->kprobe_status == KPROBE_REENTER)
 501                         restore_previous_kprobe(kcb);
 502                 else
 503                         reset_current_kprobe();
 504                 preempt_enable_no_resched();
 505                 break;
 506         case KPROBE_HIT_ACTIVE:
 507         case KPROBE_HIT_SSDONE:
 508                 /*
 509                  * We increment the nmissed count for accounting,
 510                  * we can also use npre/npostfault count for accouting
 511                  * these specific fault cases.
 512                  */
 513                 kprobes_inc_nmissed_count(cur);
 514
 515                 /*
 516                  * We come here because instructions in the pre/post
 517                  * handler caused the page_fault, this could happen
 518                  * if handler tries to access user space by
 519                  * copy_from_user(), get_user() etc. Let the
 520                  * user-specified handler try to fix it first.
 521                  */
 522                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 523                         return 1;
 524
 525                 /*
 526                  * In case the user-specified fault handler returned
 527                  * zero, try to fix up.
 528                  */
 529                 entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
 530                 if (entry) {
 531                         regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
 532                         return 1;
 533                 }
 534
 535                 /*
 536                  * fixup_exception() could not handle it,
 537                  * Let do_page_fault() fix it.
 538                  */
 539                 break;
 540         default:
 541                 break;
 542         }
 543         return 0;
 544 }
 545
 546 /*
 547  * Wrapper routine to for handling exceptions.
 548  */
 549 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 550                                        unsigned long val, void *data)
 551 {
 552         struct die_args *args = (struct die_args *)data;
 553         int ret = NOTIFY_DONE;
 554
 555         switch (val) {
 556         case DIE_BPT:
 557                 if (kprobe_handler(args->regs))
 558                         ret = NOTIFY_STOP;
 559                 break;
 560         case DIE_SSTEP:
 561                 if (post_kprobe_handler(args->regs))
 562                         ret = NOTIFY_STOP;
 563                 break;
 564         case DIE_TRAP:
 565                 /* kprobe_running() needs smp_processor_id() */
 566                 preempt_disable();
 567                 if (kprobe_running() &&
 568                     kprobe_fault_handler(args->regs, args->trapnr))
 569                         ret = NOTIFY_STOP;
 570                 preempt_enable();
 571                 break;
 572         default:
 573                 break;
 574         }
 575         return ret;
 576 }
 577
 578 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 579 {
 580         struct jprobe *jp = container_of(p, struct jprobe, kp);
 581         unsigned long addr;
 582         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 583
 584         memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
 585
 586         /* setup return addr to the jprobe handler routine */
 587         regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
 588
 589         /* r14 is the function return address */
 590         kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];
 591         /* r15 is the stack pointer */
 592         kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];
 593         addr = (unsigned long)kcb->jprobe_saved_r15;
 594
 595         memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
 596                MIN_STACK_SIZE(addr));
 597         return 1;
 598 }
 599
 600 void __kprobes jprobe_return(void)
 601 {
 602         asm volatile(".word 0x0002");
 603 }
 604
 605 void __kprobes jprobe_return_end(void)
 606 {
 607         asm volatile("bcr 0,0");
 608 }
 609
 610 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 611 {
 612         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 613         unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);
 614
 615         /* Put the regs back */
 616         memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
 617         /* put the stack back */
 618         memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
 619                MIN_STACK_SIZE(stack_addr));
 620         preempt_enable_no_resched();
 621         return 1;
 622 }
 623
 624 static struct kprobe trampoline_p = {
 625         .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
 626         .pre_handler = trampoline_probe_handler
 627 };
 628
 629 int __init arch_init_kprobes(void)
 630 {
 631         return register_kprobe(&trampoline_p);
 632 }
 633
 634 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 635 {
 636         if (p->addr == (kprobe_opcode_t *) & kretprobe_trampoline)
 637                 return 1;
 638         return 0;
 639 }