linux/arch/s390/kernel/kprobes.c
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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 <asm/cacheflush.h>
  29#include <asm/sections.h>
  30#include <asm/uaccess.h>
  31#include <linux/module.h>
  32
  33DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
  34DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
  35
  36struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
  37
  38int __kprobes arch_prepare_kprobe(struct kprobe *p)
  39{
  40        /* Make sure the probe isn't going on a difficult instruction */
  41        if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
  42                return -EINVAL;
  43
  44        if ((unsigned long)p->addr & 0x01)
  45                return -EINVAL;
  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
  58int __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
  79void __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) >> 6) {
  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
 155static int __kprobes swap_instruction(void *aref)
 156{
 157        struct ins_replace_args *args = aref;
 158        u32 *addr;
 159        u32 instr;
 160        int err = -EFAULT;
 161
 162        /*
 163         * Text segment is read-only, hence we use stura to bypass dynamic
 164         * address translation to exchange the instruction. Since stura
 165         * always operates on four bytes, but we only want to exchange two
 166         * bytes do some calculations to get things right. In addition we
 167         * shall not cross any page boundaries (vmalloc area!) when writing
 168         * the new instruction.
 169         */
 170        addr = (u32 *)((unsigned long)args->ptr & -4UL);
 171        if ((unsigned long)args->ptr & 2)
 172                instr = ((*addr) & 0xffff0000) | args->new;
 173        else
 174                instr = ((*addr) & 0x0000ffff) | args->new << 16;
 175
 176        asm volatile(
 177                "       lra     %1,0(%1)\n"
 178                "0:     stura   %2,%1\n"
 179                "1:     la      %0,0\n"
 180                "2:\n"
 181                EX_TABLE(0b,2b)
 182                : "+d" (err)
 183                : "a" (addr), "d" (instr)
 184                : "memory", "cc");
 185
 186        return err;
 187}
 188
 189void __kprobes arch_arm_kprobe(struct kprobe *p)
 190{
 191        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 192        unsigned long status = kcb->kprobe_status;
 193        struct ins_replace_args args;
 194
 195        args.ptr = p->addr;
 196        args.old = p->opcode;
 197        args.new = BREAKPOINT_INSTRUCTION;
 198
 199        kcb->kprobe_status = KPROBE_SWAP_INST;
 200        stop_machine(swap_instruction, &args, NULL);
 201        kcb->kprobe_status = status;
 202}
 203
 204void __kprobes arch_disarm_kprobe(struct kprobe *p)
 205{
 206        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 207        unsigned long status = kcb->kprobe_status;
 208        struct ins_replace_args args;
 209
 210        args.ptr = p->addr;
 211        args.old = BREAKPOINT_INSTRUCTION;
 212        args.new = p->opcode;
 213
 214        kcb->kprobe_status = KPROBE_SWAP_INST;
 215        stop_machine(swap_instruction, &args, NULL);
 216        kcb->kprobe_status = status;
 217}
 218
 219void __kprobes arch_remove_kprobe(struct kprobe *p)
 220{
 221        mutex_lock(&kprobe_mutex);
 222        free_insn_slot(p->ainsn.insn, 0);
 223        mutex_unlock(&kprobe_mutex);
 224}
 225
 226static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 227{
 228        per_cr_bits kprobe_per_regs[1];
 229
 230        memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
 231        regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
 232
 233        /* Set up the per control reg info, will pass to lctl */
 234        kprobe_per_regs[0].em_instruction_fetch = 1;
 235        kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
 236        kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
 237
 238        /* Set the PER control regs, turns on single step for this address */
 239        __ctl_load(kprobe_per_regs, 9, 11);
 240        regs->psw.mask |= PSW_MASK_PER;
 241        regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
 242}
 243
 244static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 245{
 246        kcb->prev_kprobe.kp = kprobe_running();
 247        kcb->prev_kprobe.status = kcb->kprobe_status;
 248        kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
 249        memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
 250                                        sizeof(kcb->kprobe_saved_ctl));
 251}
 252
 253static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 254{
 255        __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
 256        kcb->kprobe_status = kcb->prev_kprobe.status;
 257        kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
 258        memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
 259                                        sizeof(kcb->kprobe_saved_ctl));
 260}
 261
 262static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 263                                                struct kprobe_ctlblk *kcb)
 264{
 265        __get_cpu_var(current_kprobe) = p;
 266        /* Save the interrupt and per flags */
 267        kcb->kprobe_saved_imask = regs->psw.mask &
 268            (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
 269        /* Save the control regs that govern PER */
 270        __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
 271}
 272
 273void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 274                                        struct pt_regs *regs)
 275{
 276        ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
 277
 278        /* Replace the return addr with trampoline addr */
 279        regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
 280}
 281
 282static int __kprobes kprobe_handler(struct pt_regs *regs)
 283{
 284        struct kprobe *p;
 285        int ret = 0;
 286        unsigned long *addr = (unsigned long *)
 287                ((regs->psw.addr & PSW_ADDR_INSN) - 2);
 288        struct kprobe_ctlblk *kcb;
 289
 290        /*
 291         * We don't want to be preempted for the entire
 292         * duration of kprobe processing
 293         */
 294        preempt_disable();
 295        kcb = get_kprobe_ctlblk();
 296
 297        /* Check we're not actually recursing */
 298        if (kprobe_running()) {
 299                p = get_kprobe(addr);
 300                if (p) {
 301                        if (kcb->kprobe_status == KPROBE_HIT_SS &&
 302                            *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
 303                                regs->psw.mask &= ~PSW_MASK_PER;
 304                                regs->psw.mask |= kcb->kprobe_saved_imask;
 305                                goto no_kprobe;
 306                        }
 307                        /* We have reentered the kprobe_handler(), since
 308                         * another probe was hit while within the handler.
 309                         * We here save the original kprobes variables and
 310                         * just single step on the instruction of the new probe
 311                         * without calling any user handlers.
 312                         */
 313                        save_previous_kprobe(kcb);
 314                        set_current_kprobe(p, regs, kcb);
 315                        kprobes_inc_nmissed_count(p);
 316                        prepare_singlestep(p, regs);
 317                        kcb->kprobe_status = KPROBE_REENTER;
 318                        return 1;
 319                } else {
 320                        p = __get_cpu_var(current_kprobe);
 321                        if (p->break_handler && p->break_handler(p, regs)) {
 322                                goto ss_probe;
 323                        }
 324                }
 325                goto no_kprobe;
 326        }
 327
 328        p = get_kprobe(addr);
 329        if (!p)
 330                /*
 331                 * No kprobe at this address. The fault has not been
 332                 * caused by a kprobe breakpoint. The race of breakpoint
 333                 * vs. kprobe remove does not exist because on s390 we
 334                 * use stop_machine to arm/disarm the breakpoints.
 335                 */
 336                goto no_kprobe;
 337
 338        kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 339        set_current_kprobe(p, regs, kcb);
 340        if (p->pre_handler && p->pre_handler(p, regs))
 341                /* handler has already set things up, so skip ss setup */
 342                return 1;
 343
 344ss_probe:
 345        prepare_singlestep(p, regs);
 346        kcb->kprobe_status = KPROBE_HIT_SS;
 347        return 1;
 348
 349no_kprobe:
 350        preempt_enable_no_resched();
 351        return ret;
 352}
 353
 354/*
 355 * Function return probe trampoline:
 356 *      - init_kprobes() establishes a probepoint here
 357 *      - When the probed function returns, this probe
 358 *              causes the handlers to fire
 359 */
 360static void __used kretprobe_trampoline_holder(void)
 361{
 362        asm volatile(".global kretprobe_trampoline\n"
 363                     "kretprobe_trampoline: bcr 0,0\n");
 364}
 365
 366/*
 367 * Called when the probe at kretprobe trampoline is hit
 368 */
 369static int __kprobes trampoline_probe_handler(struct kprobe *p,
 370                                              struct pt_regs *regs)
 371{
 372        struct kretprobe_instance *ri = NULL;
 373        struct hlist_head *head, empty_rp;
 374        struct hlist_node *node, *tmp;
 375        unsigned long flags, orig_ret_address = 0;
 376        unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
 377
 378        INIT_HLIST_HEAD(&empty_rp);
 379        kretprobe_hash_lock(current, &head, &flags);
 380
 381        /*
 382         * It is possible to have multiple instances associated with a given
 383         * task either because an multiple functions in the call path
 384         * have a return probe installed on them, and/or more then one return
 385         * return probe was registered for a target function.
 386         *
 387         * We can handle this because:
 388         *     - instances are always inserted at the head of the list
 389         *     - when multiple return probes are registered for the same
 390         *       function, the first instance's ret_addr will point to the
 391         *       real return address, and all the rest will point to
 392         *       kretprobe_trampoline
 393         */
 394        hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 395                if (ri->task != current)
 396                        /* another task is sharing our hash bucket */
 397                        continue;
 398
 399                if (ri->rp && ri->rp->handler)
 400                        ri->rp->handler(ri, regs);
 401
 402                orig_ret_address = (unsigned long)ri->ret_addr;
 403                recycle_rp_inst(ri, &empty_rp);
 404
 405                if (orig_ret_address != trampoline_address) {
 406                        /*
 407                         * This is the real return address. Any other
 408                         * instances associated with this task are for
 409                         * other calls deeper on the call stack
 410                         */
 411                        break;
 412                }
 413        }
 414        kretprobe_assert(ri, orig_ret_address, trampoline_address);
 415        regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
 416
 417        reset_current_kprobe();
 418        kretprobe_hash_unlock(current, &flags);
 419        preempt_enable_no_resched();
 420
 421        hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 422                hlist_del(&ri->hlist);
 423                kfree(ri);
 424        }
 425        /*
 426         * By returning a non-zero value, we are telling
 427         * kprobe_handler() that we don't want the post_handler
 428         * to run (and have re-enabled preemption)
 429         */
 430        return 1;
 431}
 432
 433/*
 434 * Called after single-stepping.  p->addr is the address of the
 435 * instruction whose first byte has been replaced by the "breakpoint"
 436 * instruction.  To avoid the SMP problems that can occur when we
 437 * temporarily put back the original opcode to single-step, we
 438 * single-stepped a copy of the instruction.  The address of this
 439 * copy is p->ainsn.insn.
 440 */
 441static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 442{
 443        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 444
 445        regs->psw.addr &= PSW_ADDR_INSN;
 446
 447        if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
 448                regs->psw.addr = (unsigned long)p->addr +
 449                                ((unsigned long)regs->psw.addr -
 450                                 (unsigned long)p->ainsn.insn);
 451
 452        if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
 453                if ((unsigned long)regs->psw.addr -
 454                    (unsigned long)p->ainsn.insn == p->ainsn.ilen)
 455                        regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
 456
 457        if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
 458                regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
 459                                                (regs->gprs[p->ainsn.reg] -
 460                                                (unsigned long)p->ainsn.insn))
 461                                                | PSW_ADDR_AMODE;
 462
 463        regs->psw.addr |= PSW_ADDR_AMODE;
 464        /* turn off PER mode */
 465        regs->psw.mask &= ~PSW_MASK_PER;
 466        /* Restore the original per control regs */
 467        __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
 468        regs->psw.mask |= kcb->kprobe_saved_imask;
 469}
 470
 471static int __kprobes post_kprobe_handler(struct pt_regs *regs)
 472{
 473        struct kprobe *cur = kprobe_running();
 474        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 475
 476        if (!cur)
 477                return 0;
 478
 479        if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
 480                kcb->kprobe_status = KPROBE_HIT_SSDONE;
 481                cur->post_handler(cur, regs, 0);
 482        }
 483
 484        resume_execution(cur, regs);
 485
 486        /*Restore back the original saved kprobes variables and continue. */
 487        if (kcb->kprobe_status == KPROBE_REENTER) {
 488                restore_previous_kprobe(kcb);
 489                goto out;
 490        }
 491        reset_current_kprobe();
 492out:
 493        preempt_enable_no_resched();
 494
 495        /*
 496         * if somebody else is singlestepping across a probe point, psw mask
 497         * will have PER set, in which case, continue the remaining processing
 498         * of do_single_step, as if this is not a probe hit.
 499         */
 500        if (regs->psw.mask & PSW_MASK_PER) {
 501                return 0;
 502        }
 503
 504        return 1;
 505}
 506
 507int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 508{
 509        struct kprobe *cur = kprobe_running();
 510        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 511        const struct exception_table_entry *entry;
 512
 513        switch(kcb->kprobe_status) {
 514        case KPROBE_SWAP_INST:
 515                /* We are here because the instruction replacement failed */
 516                return 0;
 517        case KPROBE_HIT_SS:
 518        case KPROBE_REENTER:
 519                /*
 520                 * We are here because the instruction being single
 521                 * stepped caused a page fault. We reset the current
 522                 * kprobe and the nip points back to the probe address
 523                 * and allow the page fault handler to continue as a
 524                 * normal page fault.
 525                 */
 526                regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
 527                regs->psw.mask &= ~PSW_MASK_PER;
 528                regs->psw.mask |= kcb->kprobe_saved_imask;
 529                if (kcb->kprobe_status == KPROBE_REENTER)
 530                        restore_previous_kprobe(kcb);
 531                else
 532                        reset_current_kprobe();
 533                preempt_enable_no_resched();
 534                break;
 535        case KPROBE_HIT_ACTIVE:
 536        case KPROBE_HIT_SSDONE:
 537                /*
 538                 * We increment the nmissed count for accounting,
 539                 * we can also use npre/npostfault count for accouting
 540                 * these specific fault cases.
 541                 */
 542                kprobes_inc_nmissed_count(cur);
 543
 544                /*
 545                 * We come here because instructions in the pre/post
 546                 * handler caused the page_fault, this could happen
 547                 * if handler tries to access user space by
 548                 * copy_from_user(), get_user() etc. Let the
 549                 * user-specified handler try to fix it first.
 550                 */
 551                if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
 552                        return 1;
 553
 554                /*
 555                 * In case the user-specified fault handler returned
 556                 * zero, try to fix up.
 557                 */
 558                entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
 559                if (entry) {
 560                        regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
 561                        return 1;
 562                }
 563
 564                /*
 565                 * fixup_exception() could not handle it,
 566                 * Let do_page_fault() fix it.
 567                 */
 568                break;
 569        default:
 570                break;
 571        }
 572        return 0;
 573}
 574
 575/*
 576 * Wrapper routine to for handling exceptions.
 577 */
 578int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 579                                       unsigned long val, void *data)
 580{
 581        struct die_args *args = (struct die_args *)data;
 582        int ret = NOTIFY_DONE;
 583
 584        switch (val) {
 585        case DIE_BPT:
 586                if (kprobe_handler(args->regs))
 587                        ret = NOTIFY_STOP;
 588                break;
 589        case DIE_SSTEP:
 590                if (post_kprobe_handler(args->regs))
 591                        ret = NOTIFY_STOP;
 592                break;
 593        case DIE_TRAP:
 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
 607int __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
 629void __kprobes jprobe_return(void)
 630{
 631        asm volatile(".word 0x0002");
 632}
 633
 634void __kprobes jprobe_return_end(void)
 635{
 636        asm volatile("bcr 0,0");
 637}
 638
 639int __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
 653static struct kprobe trampoline_p = {
 654        .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
 655        .pre_handler = trampoline_probe_handler
 656};
 657
 658int __init arch_init_kprobes(void)
 659{
 660        return register_kprobe(&trampoline_p);
 661}
 662
 663int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 664{
 665        if (p->addr == (kprobe_opcode_t *) & kretprobe_trampoline)
 666                return 1;
 667        return 0;
 668}
 669