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 <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 #include <linux/hardirq.h>
  34
  35 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
  36 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
  37
  38 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
  39
  40 int __kprobes arch_prepare_kprobe(struct kprobe *p)
  41 {
  42         /* Make sure the probe isn't going on a difficult instruction */
  43         if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
  44                 return -EINVAL;
  45
  46         if ((unsigned long)p->addr & 0x01)
  47                 return -EINVAL;
  48
  49         /* Use the get_insn_slot() facility for correctness */
  50         if (!(p->ainsn.insn = get_insn_slot()))
  51                 return -ENOMEM;
  52
  53         memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
  54
  55         get_instruction_type(&p->ainsn);
  56         p->opcode = *p->addr;
  57         return 0;
  58 }
  59
  60 int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
  61 {
  62         switch (*(__u8 *) instruction) {
  63         case 0x0c:      /* bassm */
  64         case 0x0b:      /* bsm   */
  65         case 0x83:      /* diag  */
  66         case 0x44:      /* ex    */
  67         case 0xac:      /* stnsm */
  68         case 0xad:      /* stosm */
  69                 return -EINVAL;
  70         }
  71         switch (*(__u16 *) instruction) {
  72         case 0x0101:    /* pr    */
  73         case 0xb25a:    /* bsa   */
  74         case 0xb240:    /* bakr  */
  75         case 0xb258:    /* bsg   */
  76         case 0xb218:    /* pc    */
  77         case 0xb228:    /* pt    */
  78         case 0xb98d:    /* epsw  */
  79                 return -EINVAL;
  80         }
  81         return 0;
  82 }
  83
  84 void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
  85 {
  86         /* default fixup method */
  87         ainsn->fixup = FIXUP_PSW_NORMAL;
  88
  89         /* save r1 operand */
  90         ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
  91
  92         /* save the instruction length (pop 5-5) in bytes */
  93         switch (*(__u8 *) (ainsn->insn) >> 6) {
  94         case 0:
  95                 ainsn->ilen = 2;
  96                 break;
  97         case 1:
  98         case 2:
  99                 ainsn->ilen = 4;
 100                 break;
 101         case 3:
 102                 ainsn->ilen = 6;
 103                 break;
 104         }
 105
 106         switch (*(__u8 *) ainsn->insn) {
 107         case 0x05:      /* balr */
 108         case 0x0d:      /* basr */
 109                 ainsn->fixup = FIXUP_RETURN_REGISTER;
 110                 /* if r2 = 0, no branch will be taken */
 111                 if ((*ainsn->insn & 0x0f) == 0)
 112                         ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
 113                 break;
 114         case 0x06:      /* bctr */
 115         case 0x07:      /* bcr  */
 116                 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 117                 break;
 118         case 0x45:      /* bal  */
 119         case 0x4d:      /* bas  */
 120                 ainsn->fixup = FIXUP_RETURN_REGISTER;
 121                 break;
 122         case 0x47:      /* bc   */
 123         case 0x46:      /* bct  */
 124         case 0x86:      /* bxh  */
 125         case 0x87:      /* bxle */
 126                 ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 127                 break;
 128         case 0x82:      /* lpsw */
 129                 ainsn->fixup = FIXUP_NOT_REQUIRED;
 130                 break;
 131         case 0xb2:      /* lpswe */
 132                 if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
 133                         ainsn->fixup = FIXUP_NOT_REQUIRED;
 134                 }
 135                 break;
 136         case 0xa7:      /* bras */
 137                 if ((*ainsn->insn & 0x0f) == 0x05) {
 138                         ainsn->fixup |= FIXUP_RETURN_REGISTER;
 139                 }
 140                 break;
 141         case 0xc0:
 142                 if ((*ainsn->insn & 0x0f) == 0x00  /* larl  */
 143                         || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
 144                 ainsn->fixup |= FIXUP_RETURN_REGISTER;
 145                 break;
 146         case 0xeb:
 147                 if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 ||   /* bxhg  */
 148                         *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
 149                         ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 150                 }
 151                 break;
 152         case 0xe3:      /* bctg */
 153                 if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
 154                         ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
 155                 }
 156                 break;
 157         }
 158 }
 159
 160 static int __kprobes swap_instruction(void *aref)
 161 {
 162         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 163         unsigned long status = kcb->kprobe_status;
 164         struct ins_replace_args *args = aref;
 165         int rc;
 166
 167         kcb->kprobe_status = KPROBE_SWAP_INST;
 168         rc = probe_kernel_write(args->ptr, &args->new, sizeof(args->new));
 169         kcb->kprobe_status = status;
 170         return rc;
 171 }
 172
 173 void __kprobes arch_arm_kprobe(struct kprobe *p)
 174 {
 175         struct ins_replace_args args;
 176
 177         args.ptr = p->addr;
 178         args.old = p->opcode;
 179         args.new = BREAKPOINT_INSTRUCTION;
 180         stop_machine(swap_instruction, &args, NULL);
 181 }
 182
 183 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 184 {
 185         struct ins_replace_args args;
 186
 187         args.ptr = p->addr;
 188         args.old = BREAKPOINT_INSTRUCTION;
 189         args.new = p->opcode;
 190         stop_machine(swap_instruction, &args, NULL);
 191 }
 192
 193 void __kprobes arch_remove_kprobe(struct kprobe *p)
 194 {
 195         if (p->ainsn.insn) {
 196                 free_insn_slot(p->ainsn.insn, 0);
 197                 p->ainsn.insn = NULL;
 198         }
 199 }
 200
 201 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 202 {
 203         per_cr_bits kprobe_per_regs[1];
 204
 205         memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
 206         regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
 207
 208         /* Set up the per control reg info, will pass to lctl */
 209         kprobe_per_regs[0].em_instruction_fetch = 1;
 210         kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
 211         kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
 212
 213         /* Set the PER control regs, turns on single step for this address */
 214         __ctl_load(kprobe_per_regs, 9, 11);
 215         regs->psw.mask |= PSW_MASK_PER;
 216         regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
 217 }
 218
 219 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 220 {
 221         kcb->prev_kprobe.kp = kprobe_running();
 222         kcb->prev_kprobe.status = kcb->kprobe_status;
 223         kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
 224         memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
 225                                         sizeof(kcb->kprobe_saved_ctl));
 226 }
 227
 228 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 229 {
 230         __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 231         kcb->kprobe_status = kcb->prev_kprobe.status;
 232         kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
 233         memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
 234                                         sizeof(kcb->kprobe_saved_ctl));
 235 }
 236
 237 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 238                                                 struct kprobe_ctlblk *kcb)
 239 {
 240         __get_cpu_var(current_kprobe) = p;
 241         /* Save the interrupt and per flags */
 242         kcb->kprobe_saved_imask = regs->psw.mask &
 243                 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
 244         /* Save the control regs that govern PER */
 245         __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
 246 }
 247
 248 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 249                                         struct pt_regs *regs)
 250 {
 251         ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
 252
 253         /* Replace the return addr with trampoline addr */
 254         regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
 255 }
 256
 257 static int __kprobes kprobe_handler(struct pt_regs *regs)
 258 {
 259         struct kprobe *p;
 260         int ret = 0;
 261         unsigned long *addr = (unsigned long *)
 262                 ((regs->psw.addr & PSW_ADDR_INSN) - 2);
 263         struct kprobe_ctlblk *kcb;
 264
 265         /*
 266          * We don't want to be preempted for the entire
 267          * duration of kprobe processing
 268          */
 269         preempt_disable();
 270         kcb = get_kprobe_ctlblk();
 271
 272         /* Check we're not actually recursing */
 273         if (kprobe_running()) {
 274                 p = get_kprobe(addr);
 275                 if (p) {
 276                         if (kcb->kprobe_status == KPROBE_HIT_SS &&
 277                             *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
 278                                 regs->psw.mask &= ~PSW_MASK_PER;
 279                                 regs->psw.mask |= kcb->kprobe_saved_imask;
 280                                 goto no_kprobe;
 281                         }
 282                         /* We have reentered the kprobe_handler(), since
 283                          * another probe was hit while within the handler.
 284                          * We here save the original kprobes variables and
 285                          * just single step on the instruction of the new probe
 286                          * without calling any user handlers.
 287                          */
 288                         save_previous_kprobe(kcb);
 289                         set_current_kprobe(p, regs, kcb);
 290                         kprobes_inc_nmissed_count(p);
 291                         prepare_singlestep(p, regs);
 292                         kcb->kprobe_status = KPROBE_REENTER;
 293                         return 1;
 294                 } else {
 295                         p = __get_cpu_var(current_kprobe);
 296                         if (p->break_handler && p->break_handler(p, regs)) {
 297                                 goto ss_probe;
 298                         }
 299                 }
 300                 goto no_kprobe;
 301         }
 302
 303         p = get_kprobe(addr);
 304         if (!p)
 305                 /*
 306                  * No kprobe at this address. The fault has not been
 307                  * caused by a kprobe breakpoint. The race of breakpoint
 308                  * vs. kprobe remove does not exist because on s390 we
 309                  * use stop_machine to arm/disarm the breakpoints.
 310                  */
 311                 goto no_kprobe;
 312
 313         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 314         set_current_kprobe(p, regs, kcb);
 315         if (p->pre_handler && p->pre_handler(p, regs))
 316                 /* handler has already set things up, so skip ss setup */
 317                 return 1;
 318
 319 ss_probe:
 320         prepare_singlestep(p, regs);
 321         kcb->kprobe_status = KPROBE_HIT_SS;
 322         return 1;
 323
 324 no_kprobe:
 325         preempt_enable_no_resched();
 326         return ret;
 327 }
 328
 329 /*
 330  * Function return probe trampoline:
 331  *      - init_kprobes() establishes a probepoint here
 332  *      - When the probed function returns, this probe
 333  *              causes the handlers to fire
 334  */
 335 static void __used kretprobe_trampoline_holder(void)
 336 {
 337         asm volatile(".global kretprobe_trampoline\n"
 338                      "kretprobe_trampoline: bcr 0,0\n");
 339 }
 340
 341 /*
 342  * Called when the probe at kretprobe trampoline is hit
 343  */
 344 static int __kprobes trampoline_probe_handler(struct kprobe *p,
 345                                               struct pt_regs *regs)
 346 {
 347         struct kretprobe_instance *ri = NULL;
 348         struct hlist_head *head, empty_rp;
 349         struct hlist_node *node, *tmp;
 350         unsigned long flags, orig_ret_address = 0;
 351         unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
 352         kprobe_opcode_t *correct_ret_addr = NULL;
 353
 354         INIT_HLIST_HEAD(&empty_rp);
 355         kretprobe_hash_lock(current, &head, &flags);
 356
 357         /*
 358          * It is possible to have multiple instances associated with a given
 359          * task either because an multiple functions in the call path
 360          * have a return probe installed on them, and/or more than one return
 361          * return probe was registered for a target function.
 362          *
 363          * We can handle this because:
 364          *     - instances are always inserted at the head of the list
 365          *     - when multiple return probes are registered for the same
 366          *       function, the first instance's ret_addr will point to the
 367          *       real return address, and all the rest will point to
 368          *       kretprobe_trampoline
 369          */
 370         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 371                 if (ri->task != current)
 372                         /* another task is sharing our hash bucket */
 373                         continue;
 374
 375                 orig_ret_address = (unsigned long)ri->ret_addr;
 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         kretprobe_assert(ri, orig_ret_address, trampoline_address);
 387
 388         correct_ret_addr = ri->ret_addr;
 389         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 390                 if (ri->task != current)
 391                         /* another task is sharing our hash bucket */
 392                         continue;
 393
 394                 orig_ret_address = (unsigned long)ri->ret_addr;
 395
 396                 if (ri->rp && ri->rp->handler) {
 397                         ri->ret_addr = correct_ret_addr;
 398                         ri->rp->handler(ri, regs);
 399                 }
 400
 401                 recycle_rp_inst(ri, &empty_rp);
 402
 403                 if (orig_ret_address != trampoline_address) {
 404                         /*
 405                          * This is the real return address. Any other
 406                          * instances associated with this task are for
 407                          * other calls deeper on the call stack
 408                          */
 409                         break;
 410                 }
 411         }
 412
 413         regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
 414
 415         reset_current_kprobe();
 416         kretprobe_hash_unlock(current, &flags);
 417         preempt_enable_no_resched();
 418
 419         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 420                 hlist_del(&ri->hlist);
 421                 kfree(ri);
 422         }
 423         /*
 424          * By returning a non-zero value, we are telling
 425          * kprobe_handler() that we don't want the post_handler
 426          * to run (and have re-enabled preemption)
 427          */
 428         return 1;
 429 }
 430
 431 /*
 432  * Called after single-stepping.  p->addr is the address of the
 433  * instruction whose first byte has been replaced by the "breakpoint"
 434  * instruction.  To avoid the SMP problems that can occur when we
 435  * temporarily put back the original opcode to single-step, we
 436  * single-stepped a copy of the instruction.  The address of this
 437  * copy is p->ainsn.insn.
 438  */
 439 static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 440 {
 441         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 442
 443         regs->psw.addr &= PSW_ADDR_INSN;
 444
 445         if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
 446                 regs->psw.addr = (unsigned long)p->addr +
 447                                 ((unsigned long)regs->psw.addr -
 448                                  (unsigned long)p->ainsn.insn);
 449
 450         if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
 451                 if ((unsigned long)regs->psw.addr -
 452                     (unsigned long)p->ainsn.insn == p->ainsn.ilen)
 453                         regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
 454
 455         if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
 456                 regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
 457                                                 (regs->gprs[p->ainsn.reg] -
 458                                                 (unsigned long)p->ainsn.insn))
 459                                                 | PSW_ADDR_AMODE;
 460
 461         regs->psw.addr |= PSW_ADDR_AMODE;
 462         /* turn off PER mode */
 463         regs->psw.mask &= ~PSW_MASK_PER;
 464         /* Restore the original per control regs */
 465         __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
 466         regs->psw.mask |= kcb->kprobe_saved_imask;
 467 }
 468
 469 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
 470 {
 471         struct kprobe *cur = kprobe_running();
 472         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 473
 474         if (!cur)
 475                 return 0;
 476
 477         if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 478                 kcb->kprobe_status = KPROBE_HIT_SSDONE;
 479                 cur->post_handler(cur, regs, 0);
 480         }
 481
 482         resume_execution(cur, regs);
 483
 484         /*Restore back the original saved kprobes variables and continue. */
 485         if (kcb->kprobe_status == KPROBE_REENTER) {
 486                 restore_previous_kprobe(kcb);
 487                 goto out;
 488         }
 489         reset_current_kprobe();
 490 out:
 491         preempt_enable_no_resched();
 492
 493         /*
 494          * if somebody else is singlestepping across a probe point, psw mask
 495          * will have PER set, in which case, continue the remaining processing
 496          * of do_single_step, as if this is not a probe hit.
 497          */
 498         if (regs->psw.mask & PSW_MASK_PER) {
 499                 return 0;
 500         }
 501
 502         return 1;
 503 }
 504
 505 static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr)
 506 {
 507         struct kprobe *cur = kprobe_running();
 508         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 509         const struct exception_table_entry *entry;
 510
 511         switch(kcb->kprobe_status) {
 512         case KPROBE_SWAP_INST:
 513                 /* We are here because the instruction replacement failed */
 514                 return 0;
 515         case KPROBE_HIT_SS:
 516         case KPROBE_REENTER:
 517                 /*
 518                  * We are here because the instruction being single
 519                  * stepped caused a page fault. We reset the current
 520                  * kprobe and the nip points back to the probe address
 521                  * and allow the page fault handler to continue as a
 522                  * normal page fault.
 523                  */
 524                 regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
 525                 regs->psw.mask &= ~PSW_MASK_PER;
 526                 regs->psw.mask |= kcb->kprobe_saved_imask;
 527                 if (kcb->kprobe_status == KPROBE_REENTER)
 528                         restore_previous_kprobe(kcb);
 529                 else {
 530                         reset_current_kprobe();
 531                 }
 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 int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 575 {
 576         int ret;
 577
 578         if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
 579                 local_irq_disable();
 580         ret = kprobe_trap_handler(regs, trapnr);
 581         if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
 582                 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
 583         return ret;
 584 }
 585
 586 /*
 587  * Wrapper routine to for handling exceptions.
 588  */
 589 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 590                                        unsigned long val, void *data)
 591 {
 592         struct die_args *args = (struct die_args *)data;
 593         struct pt_regs *regs = args->regs;
 594         int ret = NOTIFY_DONE;
 595
 596         if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
 597                 local_irq_disable();
 598
 599         switch (val) {
 600         case DIE_BPT:
 601                 if (kprobe_handler(args->regs))
 602                         ret = NOTIFY_STOP;
 603                 break;
 604         case DIE_SSTEP:
 605                 if (post_kprobe_handler(args->regs))
 606                         ret = NOTIFY_STOP;
 607                 break;
 608         case DIE_TRAP:
 609                 if (!preemptible() && kprobe_running() &&
 610                     kprobe_trap_handler(args->regs, args->trapnr))
 611                         ret = NOTIFY_STOP;
 612                 break;
 613         default:
 614                 break;
 615         }
 616
 617         if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
 618                 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
 619
 620         return ret;
 621 }
 622
 623 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 624 {
 625         struct jprobe *jp = container_of(p, struct jprobe, kp);
 626         unsigned long addr;
 627         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 628
 629         memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
 630
 631         /* setup return addr to the jprobe handler routine */
 632         regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
 633         regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
 634
 635         /* r14 is the function return address */
 636         kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];
 637         /* r15 is the stack pointer */
 638         kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];
 639         addr = (unsigned long)kcb->jprobe_saved_r15;
 640
 641         memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
 642                MIN_STACK_SIZE(addr));
 643         return 1;
 644 }
 645
 646 void __kprobes jprobe_return(void)
 647 {
 648         asm volatile(".word 0x0002");
 649 }
 650
 651 void __kprobes jprobe_return_end(void)
 652 {
 653         asm volatile("bcr 0,0");
 654 }
 655
 656 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 657 {
 658         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 659         unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);
 660
 661         /* Put the regs back */
 662         memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
 663         /* put the stack back */
 664         memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
 665                MIN_STACK_SIZE(stack_addr));
 666         preempt_enable_no_resched();
 667         return 1;
 668 }
 669
 670 static struct kprobe trampoline_p = {
 671         .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
 672         .pre_handler = trampoline_probe_handler
 673 };
 674
 675 int __init arch_init_kprobes(void)
 676 {
 677         return register_kprobe(&trampoline_p);
 678 }
 679
 680 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 681 {
 682         if (p->addr == (kprobe_opcode_t *) & kretprobe_trampoline)
 683                 return 1;
 684         return 0;
 685 }