arch/s390/kernel/kprobes.c

   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 <asm/cacheflush.h>
  28 #include <asm/kdebug.h>
  29 #include <asm/sections.h>
  30 #include <asm/uaccess.h>
  31 #include <linux/module.h>
  32
  33 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
  34 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
  35
  36 int __kprobes arch_prepare_kprobe(struct kprobe *p)
  37 {
  38         /* Make sure the probe isn't going on a difficult instruction */
  39         if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
  40                 return -EINVAL;
  41
  42         if ((unsigned long)p->addr & 0x01) {
  43                 printk("Attempt to register kprobe at an unaligned address\n");
  44                 return -EINVAL;
  45                 }
  46
  47         /* Use the get_insn_slot() facility for correctness */
  48         if (!(p->ainsn.insn = get_insn_slot()))
  49                 return -ENOMEM;
  50
  51         memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
  52
  53         get_instruction_type(&p->ainsn);
  54         p->opcode = *p->addr;
  55         return 0;
  56 }
  57
  58 int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
  59 {
  60         switch (*(__u8 *) instruction) {
  61         case 0x0c:      /* bassm */
  62         case 0x0b:      /* bsm   */
  63         case 0x83:      /* diag  */
  64         case 0x44:      /* ex    */
  65                 return -EINVAL;
  66         }
  67         switch (*(__u16 *) instruction) {
  68         case 0x0101:    /* pr    */
  69         case 0xb25a:    /* bsa   */
  70         case 0xb240:    /* bakr  */
  71         case 0xb258:    /* bsg   */
  72         case 0xb218:    /* pc    */
  73         case 0xb228:    /* pt    */
  74                 return -EINVAL;
  75         }
  76         return 0;
  77 }
  78
  79 void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
  80 {
  81         /* default fixup method */
  82         ainsn->fixup = FIXUP_PSW_NORMAL;
  83
  84         /* save r1 operand */
  85         ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
  86
  87         /* save the instruction length (pop 5-5) in bytes */
  88         switch (*(__u8 *) (ainsn->insn) >> 4) {
  89         case 0:
  90                 ainsn->ilen = 2;
  91                 break;
  92         case 1:
  93         case 2:
  94                 ainsn->ilen = 4;
  95                 break;
  96         case 3:
  97                 ainsn->ilen = 6;
  98                 break;
  99         }
 100
 101         switch (*(__u8 *) ainsn->insn) {
 102         case 0x05:      /* balr */
 103         case 0x0d:      /* basr */
 104                 ainsn->fixup = FIXUP_RETURN_REGISTER;
 105                 /* if r2 = 0, no branch will be taken */
 106                 if ((*ainsn->insn & 0x0f) == 0)
 107                         ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
 108                 break;
 109         case 0x06:      /* bctr */
 110         case 0x07:      /* bcr  */
 111                 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 112                 break;
 113         case 0x45:      /* bal  */
 114         case 0x4d:      /* bas  */
 115                 ainsn->fixup = FIXUP_RETURN_REGISTER;
 116                 break;
 117         case 0x47:      /* bc   */
 118         case 0x46:      /* bct  */
 119         case 0x86:      /* bxh  */
 120         case 0x87:      /* bxle */
 121                 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 122                 break;
 123         case 0x82:      /* lpsw */
 124                 ainsn->fixup = FIXUP_NOT_REQUIRED;
 125                 break;
 126         case 0xb2:      /* lpswe */
 127                 if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
 128                         ainsn->fixup = FIXUP_NOT_REQUIRED;
 129                 }
 130                 break;
 131         case 0xa7:      /* bras */
 132                 if ((*ainsn->insn & 0x0f) == 0x05) {
 133                         ainsn->fixup |= FIXUP_RETURN_REGISTER;
 134                 }
 135                 break;
 136         case 0xc0:
 137                 if ((*ainsn->insn & 0x0f) == 0x00  /* larl  */
 138                         || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
 139                 ainsn->fixup |= FIXUP_RETURN_REGISTER;
 140                 break;
 141         case 0xeb:
 142                 if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 ||   /* bxhg  */
 143                         *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
 144                         ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 145                 }
 146                 break;
 147         case 0xe3:      /* bctg */
 148                 if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
 149                         ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 150                 }
 151                 break;
 152         }
 153 }
 154
 155 static int __kprobes swap_instruction(void *aref)
 156 {
 157         struct ins_replace_args *args = aref;
 158         int err = -EFAULT;
 159
 160         asm volatile(
 161                 "0: mvc  0(2,%2),0(%3)\n"
 162                 "1: la   %0,0\n"
 163                 "2:\n"
 164                 EX_TABLE(0b,2b)
 165                 : "+d" (err), "=m" (*args->ptr)
 166                 : "a" (args->ptr), "a" (&args->new), "m" (args->new));
 167         return err;
 168 }
 169
 170 void __kprobes arch_arm_kprobe(struct kprobe *p)
 171 {
 172         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 173         unsigned long status = kcb->kprobe_status;
 174         struct ins_replace_args args;
 175
 176         args.ptr = p->addr;
 177         args.old = p->opcode;
 178         args.new = BREAKPOINT_INSTRUCTION;
 179
 180         kcb->kprobe_status = KPROBE_SWAP_INST;
 181         stop_machine_run(swap_instruction, &args, NR_CPUS);
 182         kcb->kprobe_status = status;
 183 }
 184
 185 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 186 {
 187         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 188         unsigned long status = kcb->kprobe_status;
 189         struct ins_replace_args args;
 190
 191         args.ptr = p->addr;
 192         args.old = BREAKPOINT_INSTRUCTION;
 193         args.new = p->opcode;
 194
 195         kcb->kprobe_status = KPROBE_SWAP_INST;
 196         stop_machine_run(swap_instruction, &args, NR_CPUS);
 197         kcb->kprobe_status = status;
 198 }
 199
 200 void __kprobes arch_remove_kprobe(struct kprobe *p)
 201 {
 202         mutex_lock(&kprobe_mutex);
 203         free_insn_slot(p->ainsn.insn, 0);
 204         mutex_unlock(&kprobe_mutex);
 205 }
 206
 207 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 208 {
 209         per_cr_bits kprobe_per_regs[1];
 210
 211         memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
 212         regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
 213
 214         /* Set up the per control reg info, will pass to lctl */
 215         kprobe_per_regs[0].em_instruction_fetch = 1;
 216         kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
 217         kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
 218
 219         /* Set the PER control regs, turns on single step for this address */
 220         __ctl_load(kprobe_per_regs, 9, 11);
 221         regs->psw.mask |= PSW_MASK_PER;
 222         regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
 223 }
 224
 225 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 226 {
 227         kcb->prev_kprobe.kp = kprobe_running();
 228         kcb->prev_kprobe.status = kcb->kprobe_status;
 229         kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
 230         memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
 231                                         sizeof(kcb->kprobe_saved_ctl));
 232 }
 233
 234 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 235 {
 236         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 237         kcb->kprobe_status = kcb->prev_kprobe.status;
 238         kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
 239         memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
 240                                         sizeof(kcb->kprobe_saved_ctl));
 241 }
 242
 243 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 244                                                 struct kprobe_ctlblk *kcb)
 245 {
 246         __get_cpu_var(current_kprobe) = p;
 247         /* Save the interrupt and per flags */
 248         kcb->kprobe_saved_imask = regs->psw.mask &
 249             (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
 250         /* Save the control regs that govern PER */
 251         __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
 252 }
 253
 254 /* Called with kretprobe_lock held */
 255 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
 256                                         struct pt_regs *regs)
 257 {
 258         struct kretprobe_instance *ri;
 259
 260         if ((ri = get_free_rp_inst(rp)) != NULL) {
 261                 ri->rp = rp;
 262                 ri->task = current;
 263                 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
 264
 265                 /* Replace the return addr with trampoline addr */
 266                 regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
 267
 268                 add_rp_inst(ri);
 269         } else {
 270                 rp->nmissed++;
 271         }
 272 }
 273
 274 static int __kprobes kprobe_handler(struct pt_regs *regs)
 275 {
 276         struct kprobe *p;
 277         int ret = 0;
 278         unsigned long *addr = (unsigned long *)
 279                 ((regs->psw.addr & PSW_ADDR_INSN) - 2);
 280         struct kprobe_ctlblk *kcb;
 281
 282         /*
 283          * We don't want to be preempted for the entire
 284          * duration of kprobe processing
 285          */
 286         preempt_disable();
 287         kcb = get_kprobe_ctlblk();
 288
 289         /* Check we're not actually recursing */
 290         if (kprobe_running()) {
 291                 p = get_kprobe(addr);
 292                 if (p) {
 293                         if (kcb->kprobe_status == KPROBE_HIT_SS &&
 294                             *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
 295                                 regs->psw.mask &= ~PSW_MASK_PER;
 296                                 regs->psw.mask |= kcb->kprobe_saved_imask;
 297                                 goto no_kprobe;
 298                         }
 299                         /* We have reentered the kprobe_handler(), since
 300                          * another probe was hit while within the handler.
 301                          * We here save the original kprobes variables and
 302                          * just single step on the instruction of the new probe
 303                          * without calling any user handlers.
 304                          */
 305                         save_previous_kprobe(kcb);
 306                         set_current_kprobe(p, regs, kcb);
 307                         kprobes_inc_nmissed_count(p);
 308                         prepare_singlestep(p, regs);
 309                         kcb->kprobe_status = KPROBE_REENTER;
 310                         return 1;
 311                 } else {
 312                         p = __get_cpu_var(current_kprobe);
 313                         if (p->break_handler && p->break_handler(p, regs)) {
 314                                 goto ss_probe;
 315                         }
 316                 }
 317                 goto no_kprobe;
 318         }
 319
 320         p = get_kprobe(addr);
 321         if (!p) {
 322                 if (*addr != BREAKPOINT_INSTRUCTION) {
 323                         /*
 324                          * The breakpoint instruction was removed right
 325                          * after we hit it.  Another cpu has removed
 326                          * either a probepoint or a debugger breakpoint
 327                          * at this address.  In either case, no further
 328                          * handling of this interrupt is appropriate.
 329                          *
 330                          */
 331                         ret = 1;
 332                 }
 333                 /* Not one of ours: let kernel handle it */
 334                 goto no_kprobe;
 335         }
 336
 337         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 338         set_current_kprobe(p, regs, kcb);
 339         if (p->pre_handler && p->pre_handler(p, regs))
 340                 /* handler has already set things up, so skip ss setup */
 341                 return 1;
 342
 343 ss_probe:
 344         prepare_singlestep(p, regs);
 345         kcb->kprobe_status = KPROBE_HIT_SS;
 346         return 1;
 347
 348 no_kprobe:
 349         preempt_enable_no_resched();
 350         return ret;
 351 }
 352
 353 /*
 354  * Function return probe trampoline:
 355  *      - init_kprobes() establishes a probepoint here
 356  *      - When the probed function returns, this probe
 357  *              causes the handlers to fire
 358  */
 359 void __kprobes kretprobe_trampoline_holder(void)
 360 {
 361         asm volatile(".global kretprobe_trampoline\n"
 362                      "kretprobe_trampoline: bcr 0,0\n");
 363 }
 364
 365 /*
 366  * Called when the probe at kretprobe trampoline is hit
 367  */
 368 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 369 {
 370         struct kretprobe_instance *ri = NULL;
 371         struct hlist_head *head, empty_rp;
 372         struct hlist_node *node, *tmp;
 373         unsigned long flags, orig_ret_address = 0;
 374         unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
 375
 376         INIT_HLIST_HEAD(&empty_rp);
 377         spin_lock_irqsave(&kretprobe_lock, flags);
 378         head = kretprobe_inst_table_head(current);
 379
 380         /*
 381          * It is possible to have multiple instances associated with a given
 382          * task either because an multiple functions in the call path
 383          * have a return probe installed on them, and/or more then one return
 384          * return probe was registered for a target function.
 385          *
 386          * We can handle this because:
 387          *     - instances are always inserted at the head of the list
 388          *     - when multiple return probes are registered for the same
 389          *       function, the first instance's ret_addr will point to the
 390          *       real return address, and all the rest will point to
 391          *       kretprobe_trampoline
 392          */
 393         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 394                 if (ri->task != current)
 395                         /* another task is sharing our hash bucket */
 396                         continue;
 397
 398                 if (ri->rp && ri->rp->handler)
 399                         ri->rp->handler(ri, regs);
 400
 401                 orig_ret_address = (unsigned long)ri->ret_addr;
 402                 recycle_rp_inst(ri, &empty_rp);
 403
 404                 if (orig_ret_address != trampoline_address) {
 405                         /*
 406                          * This is the real return address. Any other
 407                          * instances associated with this task are for
 408                          * other calls deeper on the call stack
 409                          */
 410                         break;
 411                 }
 412         }
 413         BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
 414         regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
 415
 416         reset_current_kprobe();
 417         spin_unlock_irqrestore(&kretprobe_lock, flags);
 418         preempt_enable_no_resched();
 419
 420         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 421                 hlist_del(&ri->hlist);
 422                 kfree(ri);
 423         }
 424         /*
 425          * By returning a non-zero value, we are telling
 426          * kprobe_handler() that we don't want the post_handler
 427          * to run (and have re-enabled preemption)
 428          */
 429         return 1;
 430 }
 431
 432 /*
 433  * Called after single-stepping.  p->addr is the address of the
 434  * instruction whose first byte has been replaced by the "breakpoint"
 435  * instruction.  To avoid the SMP problems that can occur when we
 436  * temporarily put back the original opcode to single-step, we
 437  * single-stepped a copy of the instruction.  The address of this
 438  * copy is p->ainsn.insn.
 439  */
 440 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 441 {
 442         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 443
 444         regs->psw.addr &= PSW_ADDR_INSN;
 445
 446         if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
 447                 regs->psw.addr = (unsigned long)p->addr +
 448                                 ((unsigned long)regs->psw.addr -
 449                                  (unsigned long)p->ainsn.insn);
 450
 451         if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
 452                 if ((unsigned long)regs->psw.addr -
 453                     (unsigned long)p->ainsn.insn == p->ainsn.ilen)
 454                         regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
 455
 456         if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
 457                 regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
 458                                                 (regs->gprs[p->ainsn.reg] -
 459                                                 (unsigned long)p->ainsn.insn))
 460                                                 | PSW_ADDR_AMODE;
 461
 462         regs->psw.addr |= PSW_ADDR_AMODE;
 463         /* turn off PER mode */
 464         regs->psw.mask &= ~PSW_MASK_PER;
 465         /* Restore the original per control regs */
 466         __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
 467         regs->psw.mask |= kcb->kprobe_saved_imask;
 468 }
 469
 470 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
 471 {
 472         struct kprobe *cur = kprobe_running();
 473         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 474
 475         if (!cur)
 476                 return 0;
 477
 478         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 479                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 480                 cur->post_handler(cur, regs, 0);
 481         }
 482
 483         resume_execution(cur, regs);
 484
 485         /*Restore back the original saved kprobes variables and continue. */
 486         if (kcb->kprobe_status == KPROBE_REENTER) {
 487                 restore_previous_kprobe(kcb);
 488                 goto out;
 489         }
 490         reset_current_kprobe();
 491 out:
 492         preempt_enable_no_resched();
 493
 494         /*
 495          * if somebody else is singlestepping across a probe point, psw mask
 496          * will have PER set, in which case, continue the remaining processing
 497          * of do_single_step, as if this is not a probe hit.
 498          */
 499         if (regs->psw.mask & PSW_MASK_PER) {
 500                 return 0;
 501         }
 502
 503         return 1;
 504 }
 505
 506 static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 507 {
 508         struct kprobe *cur = kprobe_running();
 509         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 510         const struct exception_table_entry *entry;
 511
 512         switch(kcb->kprobe_status) {
 513         case KPROBE_SWAP_INST:
 514                 /* We are here because the instruction replacement failed */
 515                 return 0;
 516         case KPROBE_HIT_SS:
 517         case KPROBE_REENTER:
 518                 /*
 519                  * We are here because the instruction being single
 520                  * stepped caused a page fault. We reset the current
 521                  * kprobe and the nip points back to the probe address
 522                  * and allow the page fault handler to continue as a
 523                  * normal page fault.
 524                  */
 525                 regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
 526                 regs->psw.mask &= ~PSW_MASK_PER;
 527                 regs->psw.mask |= kcb->kprobe_saved_imask;
 528                 if (kcb->kprobe_status == KPROBE_REENTER)
 529                         restore_previous_kprobe(kcb);
 530                 else
 531                         reset_current_kprobe();
 532                 preempt_enable_no_resched();
 533                 break;
 534         case KPROBE_HIT_ACTIVE:
 535         case KPROBE_HIT_SSDONE:
 536                 /*
 537                  * We increment the nmissed count for accounting,
 538                  * we can also use npre/npostfault count for accouting
 539                  * these specific fault cases.
 540                  */
 541                 kprobes_inc_nmissed_count(cur);
 542
 543                 /*
 544                  * We come here because instructions in the pre/post
 545                  * handler caused the page_fault, this could happen
 546                  * if handler tries to access user space by
 547                  * copy_from_user(), get_user() etc. Let the
 548                  * user-specified handler try to fix it first.
 549                  */
 550                 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 551                         return 1;
 552
 553                 /*
 554                  * In case the user-specified fault handler returned
 555                  * zero, try to fix up.
 556                  */
 557                 entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
 558                 if (entry) {
 559                         regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
 560                         return 1;
 561                 }
 562
 563                 /*
 564                  * fixup_exception() could not handle it,
 565                  * Let do_page_fault() fix it.
 566                  */
 567                 break;
 568         default:
 569                 break;
 570         }
 571         return 0;
 572 }
 573
 574 /*
 575  * Wrapper routine to for handling exceptions.
 576  */
 577 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 578                                        unsigned long val, void *data)
 579 {
 580         struct die_args *args = (struct die_args *)data;
 581         int ret = NOTIFY_DONE;
 582
 583         switch (val) {
 584         case DIE_BPT:
 585                 if (kprobe_handler(args->regs))
 586                         ret = NOTIFY_STOP;
 587                 break;
 588         case DIE_SSTEP:
 589                 if (post_kprobe_handler(args->regs))
 590                         ret = NOTIFY_STOP;
 591                 break;
 592         case DIE_TRAP:
 593         case DIE_PAGE_FAULT:
 594                 /* kprobe_running() needs smp_processor_id() */
 595                 preempt_disable();
 596                 if (kprobe_running() &&
 597                     kprobe_fault_handler(args->regs, args->trapnr))
 598                         ret = NOTIFY_STOP;
 599                 preempt_enable();
 600                 break;
 601         default:
 602                 break;
 603         }
 604         return ret;
 605 }
 606
 607 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 608 {
 609         struct jprobe *jp = container_of(p, struct jprobe, kp);
 610         unsigned long addr;
 611         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 612
 613         memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
 614
 615         /* setup return addr to the jprobe handler routine */
 616         regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
 617
 618         /* r14 is the function return address */
 619         kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];
 620         /* r15 is the stack pointer */
 621         kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];
 622         addr = (unsigned long)kcb->jprobe_saved_r15;
 623
 624         memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
 625                MIN_STACK_SIZE(addr));
 626         return 1;
 627 }
 628
 629 void __kprobes jprobe_return(void)
 630 {
 631         asm volatile(".word 0x0002");
 632 }
 633
 634 void __kprobes jprobe_return_end(void)
 635 {
 636         asm volatile("bcr 0,0");
 637 }
 638
 639 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 640 {
 641         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 642         unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);
 643
 644         /* Put the regs back */
 645         memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
 646         /* put the stack back */
 647         memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
 648                MIN_STACK_SIZE(stack_addr));
 649         preempt_enable_no_resched();
 650         return 1;
 651 }
 652
 653 static struct kprobe trampoline_p = {
 654         .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
 655         .pre_handler = trampoline_probe_handler
 656 };
 657
 658 int __init arch_init_kprobes(void)
 659 {
 660         return register_kprobe(&trampoline_p);
 661 }