linux/kernel/kprobes.c
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   1/*
   2 *  Kernel Probes (KProbes)
   3 *  kernel/kprobes.c
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program; if not, write to the Free Software
  17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18 *
  19 * Copyright (C) IBM Corporation, 2002, 2004
  20 *
  21 * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
  22 *              Probes initial implementation (includes suggestions from
  23 *              Rusty Russell).
  24 * 2004-Aug     Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
  25 *              hlists and exceptions notifier as suggested by Andi Kleen.
  26 * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
  27 *              interface to access function arguments.
  28 * 2004-Sep     Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
  29 *              exceptions notifier to be first on the priority list.
  30 * 2005-May     Hien Nguyen <hien@us.ibm.com>, Jim Keniston
  31 *              <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
  32 *              <prasanna@in.ibm.com> added function-return probes.
  33 */
  34#include <linux/kprobes.h>
  35#include <linux/hash.h>
  36#include <linux/init.h>
  37#include <linux/slab.h>
  38#include <linux/stddef.h>
  39#include <linux/module.h>
  40#include <linux/moduleloader.h>
  41#include <linux/kallsyms.h>
  42#include <linux/freezer.h>
  43#include <linux/seq_file.h>
  44#include <linux/debugfs.h>
  45#include <linux/sysctl.h>
  46#include <linux/kdebug.h>
  47#include <linux/memory.h>
  48#include <linux/ftrace.h>
  49#include <linux/cpu.h>
  50#include <linux/jump_label.h>
  51
  52#include <asm-generic/sections.h>
  53#include <asm/cacheflush.h>
  54#include <asm/errno.h>
  55#include <asm/uaccess.h>
  56
  57#define KPROBE_HASH_BITS 6
  58#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
  59
  60
  61/*
  62 * Some oddball architectures like 64bit powerpc have function descriptors
  63 * so this must be overridable.
  64 */
  65#ifndef kprobe_lookup_name
  66#define kprobe_lookup_name(name, addr) \
  67        addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
  68#endif
  69
  70static int kprobes_initialized;
  71static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  72static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
  73
  74/* NOTE: change this value only with kprobe_mutex held */
  75static bool kprobes_all_disarmed;
  76
  77/* This protects kprobe_table and optimizing_list */
  78static DEFINE_MUTEX(kprobe_mutex);
  79static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
  80static struct {
  81        spinlock_t lock ____cacheline_aligned_in_smp;
  82} kretprobe_table_locks[KPROBE_TABLE_SIZE];
  83
  84static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
  85{
  86        return &(kretprobe_table_locks[hash].lock);
  87}
  88
  89/*
  90 * Normally, functions that we'd want to prohibit kprobes in, are marked
  91 * __kprobes. But, there are cases where such functions already belong to
  92 * a different section (__sched for preempt_schedule)
  93 *
  94 * For such cases, we now have a blacklist
  95 */
  96static struct kprobe_blackpoint kprobe_blacklist[] = {
  97        {"preempt_schedule",},
  98        {"native_get_debugreg",},
  99        {"irq_entries_start",},
 100        {"common_interrupt",},
 101        {"mcount",},    /* mcount can be called from everywhere */
 102        {NULL}    /* Terminator */
 103};
 104
 105#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 106/*
 107 * kprobe->ainsn.insn points to the copy of the instruction to be
 108 * single-stepped. x86_64, POWER4 and above have no-exec support and
 109 * stepping on the instruction on a vmalloced/kmalloced/data page
 110 * is a recipe for disaster
 111 */
 112struct kprobe_insn_page {
 113        struct list_head list;
 114        kprobe_opcode_t *insns;         /* Page of instruction slots */
 115        int nused;
 116        int ngarbage;
 117        char slot_used[];
 118};
 119
 120#define KPROBE_INSN_PAGE_SIZE(slots)                    \
 121        (offsetof(struct kprobe_insn_page, slot_used) + \
 122         (sizeof(char) * (slots)))
 123
 124struct kprobe_insn_cache {
 125        struct list_head pages; /* list of kprobe_insn_page */
 126        size_t insn_size;       /* size of instruction slot */
 127        int nr_garbage;
 128};
 129
 130static int slots_per_page(struct kprobe_insn_cache *c)
 131{
 132        return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
 133}
 134
 135enum kprobe_slot_state {
 136        SLOT_CLEAN = 0,
 137        SLOT_DIRTY = 1,
 138        SLOT_USED = 2,
 139};
 140
 141static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
 142static struct kprobe_insn_cache kprobe_insn_slots = {
 143        .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
 144        .insn_size = MAX_INSN_SIZE,
 145        .nr_garbage = 0,
 146};
 147static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
 148
 149/**
 150 * __get_insn_slot() - Find a slot on an executable page for an instruction.
 151 * We allocate an executable page if there's no room on existing ones.
 152 */
 153static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
 154{
 155        struct kprobe_insn_page *kip;
 156
 157 retry:
 158        list_for_each_entry(kip, &c->pages, list) {
 159                if (kip->nused < slots_per_page(c)) {
 160                        int i;
 161                        for (i = 0; i < slots_per_page(c); i++) {
 162                                if (kip->slot_used[i] == SLOT_CLEAN) {
 163                                        kip->slot_used[i] = SLOT_USED;
 164                                        kip->nused++;
 165                                        return kip->insns + (i * c->insn_size);
 166                                }
 167                        }
 168                        /* kip->nused is broken. Fix it. */
 169                        kip->nused = slots_per_page(c);
 170                        WARN_ON(1);
 171                }
 172        }
 173
 174        /* If there are any garbage slots, collect it and try again. */
 175        if (c->nr_garbage && collect_garbage_slots(c) == 0)
 176                goto retry;
 177
 178        /* All out of space.  Need to allocate a new page. */
 179        kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
 180        if (!kip)
 181                return NULL;
 182
 183        /*
 184         * Use module_alloc so this page is within +/- 2GB of where the
 185         * kernel image and loaded module images reside. This is required
 186         * so x86_64 can correctly handle the %rip-relative fixups.
 187         */
 188        kip->insns = module_alloc(PAGE_SIZE);
 189        if (!kip->insns) {
 190                kfree(kip);
 191                return NULL;
 192        }
 193        INIT_LIST_HEAD(&kip->list);
 194        memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
 195        kip->slot_used[0] = SLOT_USED;
 196        kip->nused = 1;
 197        kip->ngarbage = 0;
 198        list_add(&kip->list, &c->pages);
 199        return kip->insns;
 200}
 201
 202
 203kprobe_opcode_t __kprobes *get_insn_slot(void)
 204{
 205        kprobe_opcode_t *ret = NULL;
 206
 207        mutex_lock(&kprobe_insn_mutex);
 208        ret = __get_insn_slot(&kprobe_insn_slots);
 209        mutex_unlock(&kprobe_insn_mutex);
 210
 211        return ret;
 212}
 213
 214/* Return 1 if all garbages are collected, otherwise 0. */
 215static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
 216{
 217        kip->slot_used[idx] = SLOT_CLEAN;
 218        kip->nused--;
 219        if (kip->nused == 0) {
 220                /*
 221                 * Page is no longer in use.  Free it unless
 222                 * it's the last one.  We keep the last one
 223                 * so as not to have to set it up again the
 224                 * next time somebody inserts a probe.
 225                 */
 226                if (!list_is_singular(&kip->list)) {
 227                        list_del(&kip->list);
 228                        module_free(NULL, kip->insns);
 229                        kfree(kip);
 230                }
 231                return 1;
 232        }
 233        return 0;
 234}
 235
 236static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
 237{
 238        struct kprobe_insn_page *kip, *next;
 239
 240        /* Ensure no-one is interrupted on the garbages */
 241        synchronize_sched();
 242
 243        list_for_each_entry_safe(kip, next, &c->pages, list) {
 244                int i;
 245                if (kip->ngarbage == 0)
 246                        continue;
 247                kip->ngarbage = 0;      /* we will collect all garbages */
 248                for (i = 0; i < slots_per_page(c); i++) {
 249                        if (kip->slot_used[i] == SLOT_DIRTY &&
 250                            collect_one_slot(kip, i))
 251                                break;
 252                }
 253        }
 254        c->nr_garbage = 0;
 255        return 0;
 256}
 257
 258static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
 259                                       kprobe_opcode_t *slot, int dirty)
 260{
 261        struct kprobe_insn_page *kip;
 262
 263        list_for_each_entry(kip, &c->pages, list) {
 264                long idx = ((long)slot - (long)kip->insns) /
 265                                (c->insn_size * sizeof(kprobe_opcode_t));
 266                if (idx >= 0 && idx < slots_per_page(c)) {
 267                        WARN_ON(kip->slot_used[idx] != SLOT_USED);
 268                        if (dirty) {
 269                                kip->slot_used[idx] = SLOT_DIRTY;
 270                                kip->ngarbage++;
 271                                if (++c->nr_garbage > slots_per_page(c))
 272                                        collect_garbage_slots(c);
 273                        } else
 274                                collect_one_slot(kip, idx);
 275                        return;
 276                }
 277        }
 278        /* Could not free this slot. */
 279        WARN_ON(1);
 280}
 281
 282void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
 283{
 284        mutex_lock(&kprobe_insn_mutex);
 285        __free_insn_slot(&kprobe_insn_slots, slot, dirty);
 286        mutex_unlock(&kprobe_insn_mutex);
 287}
 288#ifdef CONFIG_OPTPROBES
 289/* For optimized_kprobe buffer */
 290static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
 291static struct kprobe_insn_cache kprobe_optinsn_slots = {
 292        .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
 293        /* .insn_size is initialized later */
 294        .nr_garbage = 0,
 295};
 296/* Get a slot for optimized_kprobe buffer */
 297kprobe_opcode_t __kprobes *get_optinsn_slot(void)
 298{
 299        kprobe_opcode_t *ret = NULL;
 300
 301        mutex_lock(&kprobe_optinsn_mutex);
 302        ret = __get_insn_slot(&kprobe_optinsn_slots);
 303        mutex_unlock(&kprobe_optinsn_mutex);
 304
 305        return ret;
 306}
 307
 308void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
 309{
 310        mutex_lock(&kprobe_optinsn_mutex);
 311        __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
 312        mutex_unlock(&kprobe_optinsn_mutex);
 313}
 314#endif
 315#endif
 316
 317/* We have preemption disabled.. so it is safe to use __ versions */
 318static inline void set_kprobe_instance(struct kprobe *kp)
 319{
 320        __this_cpu_write(kprobe_instance, kp);
 321}
 322
 323static inline void reset_kprobe_instance(void)
 324{
 325        __this_cpu_write(kprobe_instance, NULL);
 326}
 327
 328/*
 329 * This routine is called either:
 330 *      - under the kprobe_mutex - during kprobe_[un]register()
 331 *                              OR
 332 *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
 333 */
 334struct kprobe __kprobes *get_kprobe(void *addr)
 335{
 336        struct hlist_head *head;
 337        struct hlist_node *node;
 338        struct kprobe *p;
 339
 340        head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
 341        hlist_for_each_entry_rcu(p, node, head, hlist) {
 342                if (p->addr == addr)
 343                        return p;
 344        }
 345
 346        return NULL;
 347}
 348
 349static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
 350
 351/* Return true if the kprobe is an aggregator */
 352static inline int kprobe_aggrprobe(struct kprobe *p)
 353{
 354        return p->pre_handler == aggr_pre_handler;
 355}
 356
 357/* Return true(!0) if the kprobe is unused */
 358static inline int kprobe_unused(struct kprobe *p)
 359{
 360        return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
 361               list_empty(&p->list);
 362}
 363
 364/*
 365 * Keep all fields in the kprobe consistent
 366 */
 367static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
 368{
 369        memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
 370        memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
 371}
 372
 373#ifdef CONFIG_OPTPROBES
 374/* NOTE: change this value only with kprobe_mutex held */
 375static bool kprobes_allow_optimization;
 376
 377/*
 378 * Call all pre_handler on the list, but ignores its return value.
 379 * This must be called from arch-dep optimized caller.
 380 */
 381void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
 382{
 383        struct kprobe *kp;
 384
 385        list_for_each_entry_rcu(kp, &p->list, list) {
 386                if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 387                        set_kprobe_instance(kp);
 388                        kp->pre_handler(kp, regs);
 389                }
 390                reset_kprobe_instance();
 391        }
 392}
 393
 394/* Free optimized instructions and optimized_kprobe */
 395static __kprobes void free_aggr_kprobe(struct kprobe *p)
 396{
 397        struct optimized_kprobe *op;
 398
 399        op = container_of(p, struct optimized_kprobe, kp);
 400        arch_remove_optimized_kprobe(op);
 401        arch_remove_kprobe(p);
 402        kfree(op);
 403}
 404
 405/* Return true(!0) if the kprobe is ready for optimization. */
 406static inline int kprobe_optready(struct kprobe *p)
 407{
 408        struct optimized_kprobe *op;
 409
 410        if (kprobe_aggrprobe(p)) {
 411                op = container_of(p, struct optimized_kprobe, kp);
 412                return arch_prepared_optinsn(&op->optinsn);
 413        }
 414
 415        return 0;
 416}
 417
 418/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
 419static inline int kprobe_disarmed(struct kprobe *p)
 420{
 421        struct optimized_kprobe *op;
 422
 423        /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
 424        if (!kprobe_aggrprobe(p))
 425                return kprobe_disabled(p);
 426
 427        op = container_of(p, struct optimized_kprobe, kp);
 428
 429        return kprobe_disabled(p) && list_empty(&op->list);
 430}
 431
 432/* Return true(!0) if the probe is queued on (un)optimizing lists */
 433static int __kprobes kprobe_queued(struct kprobe *p)
 434{
 435        struct optimized_kprobe *op;
 436
 437        if (kprobe_aggrprobe(p)) {
 438                op = container_of(p, struct optimized_kprobe, kp);
 439                if (!list_empty(&op->list))
 440                        return 1;
 441        }
 442        return 0;
 443}
 444
 445/*
 446 * Return an optimized kprobe whose optimizing code replaces
 447 * instructions including addr (exclude breakpoint).
 448 */
 449static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
 450{
 451        int i;
 452        struct kprobe *p = NULL;
 453        struct optimized_kprobe *op;
 454
 455        /* Don't check i == 0, since that is a breakpoint case. */
 456        for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
 457                p = get_kprobe((void *)(addr - i));
 458
 459        if (p && kprobe_optready(p)) {
 460                op = container_of(p, struct optimized_kprobe, kp);
 461                if (arch_within_optimized_kprobe(op, addr))
 462                        return p;
 463        }
 464
 465        return NULL;
 466}
 467
 468/* Optimization staging list, protected by kprobe_mutex */
 469static LIST_HEAD(optimizing_list);
 470static LIST_HEAD(unoptimizing_list);
 471
 472static void kprobe_optimizer(struct work_struct *work);
 473static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
 474static DECLARE_COMPLETION(optimizer_comp);
 475#define OPTIMIZE_DELAY 5
 476
 477/*
 478 * Optimize (replace a breakpoint with a jump) kprobes listed on
 479 * optimizing_list.
 480 */
 481static __kprobes void do_optimize_kprobes(void)
 482{
 483        /* Optimization never be done when disarmed */
 484        if (kprobes_all_disarmed || !kprobes_allow_optimization ||
 485            list_empty(&optimizing_list))
 486                return;
 487
 488        /*
 489         * The optimization/unoptimization refers online_cpus via
 490         * stop_machine() and cpu-hotplug modifies online_cpus.
 491         * And same time, text_mutex will be held in cpu-hotplug and here.
 492         * This combination can cause a deadlock (cpu-hotplug try to lock
 493         * text_mutex but stop_machine can not be done because online_cpus
 494         * has been changed)
 495         * To avoid this deadlock, we need to call get_online_cpus()
 496         * for preventing cpu-hotplug outside of text_mutex locking.
 497         */
 498        get_online_cpus();
 499        mutex_lock(&text_mutex);
 500        arch_optimize_kprobes(&optimizing_list);
 501        mutex_unlock(&text_mutex);
 502        put_online_cpus();
 503}
 504
 505/*
 506 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
 507 * if need) kprobes listed on unoptimizing_list.
 508 */
 509static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
 510{
 511        struct optimized_kprobe *op, *tmp;
 512
 513        /* Unoptimization must be done anytime */
 514        if (list_empty(&unoptimizing_list))
 515                return;
 516
 517        /* Ditto to do_optimize_kprobes */
 518        get_online_cpus();
 519        mutex_lock(&text_mutex);
 520        arch_unoptimize_kprobes(&unoptimizing_list, free_list);
 521        /* Loop free_list for disarming */
 522        list_for_each_entry_safe(op, tmp, free_list, list) {
 523                /* Disarm probes if marked disabled */
 524                if (kprobe_disabled(&op->kp))
 525                        arch_disarm_kprobe(&op->kp);
 526                if (kprobe_unused(&op->kp)) {
 527                        /*
 528                         * Remove unused probes from hash list. After waiting
 529                         * for synchronization, these probes are reclaimed.
 530                         * (reclaiming is done by do_free_cleaned_kprobes.)
 531                         */
 532                        hlist_del_rcu(&op->kp.hlist);
 533                } else
 534                        list_del_init(&op->list);
 535        }
 536        mutex_unlock(&text_mutex);
 537        put_online_cpus();
 538}
 539
 540/* Reclaim all kprobes on the free_list */
 541static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list)
 542{
 543        struct optimized_kprobe *op, *tmp;
 544
 545        list_for_each_entry_safe(op, tmp, free_list, list) {
 546                BUG_ON(!kprobe_unused(&op->kp));
 547                list_del_init(&op->list);
 548                free_aggr_kprobe(&op->kp);
 549        }
 550}
 551
 552/* Start optimizer after OPTIMIZE_DELAY passed */
 553static __kprobes void kick_kprobe_optimizer(void)
 554{
 555        if (!delayed_work_pending(&optimizing_work))
 556                schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
 557}
 558
 559/* Kprobe jump optimizer */
 560static __kprobes void kprobe_optimizer(struct work_struct *work)
 561{
 562        LIST_HEAD(free_list);
 563
 564        /* Lock modules while optimizing kprobes */
 565        mutex_lock(&module_mutex);
 566        mutex_lock(&kprobe_mutex);
 567
 568        /*
 569         * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
 570         * kprobes before waiting for quiesence period.
 571         */
 572        do_unoptimize_kprobes(&free_list);
 573
 574        /*
 575         * Step 2: Wait for quiesence period to ensure all running interrupts
 576         * are done. Because optprobe may modify multiple instructions
 577         * there is a chance that Nth instruction is interrupted. In that
 578         * case, running interrupt can return to 2nd-Nth byte of jump
 579         * instruction. This wait is for avoiding it.
 580         */
 581        synchronize_sched();
 582
 583        /* Step 3: Optimize kprobes after quiesence period */
 584        do_optimize_kprobes();
 585
 586        /* Step 4: Free cleaned kprobes after quiesence period */
 587        do_free_cleaned_kprobes(&free_list);
 588
 589        mutex_unlock(&kprobe_mutex);
 590        mutex_unlock(&module_mutex);
 591
 592        /* Step 5: Kick optimizer again if needed */
 593        if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
 594                kick_kprobe_optimizer();
 595        else
 596                /* Wake up all waiters */
 597                complete_all(&optimizer_comp);
 598}
 599
 600/* Wait for completing optimization and unoptimization */
 601static __kprobes void wait_for_kprobe_optimizer(void)
 602{
 603        if (delayed_work_pending(&optimizing_work))
 604                wait_for_completion(&optimizer_comp);
 605}
 606
 607/* Optimize kprobe if p is ready to be optimized */
 608static __kprobes void optimize_kprobe(struct kprobe *p)
 609{
 610        struct optimized_kprobe *op;
 611
 612        /* Check if the kprobe is disabled or not ready for optimization. */
 613        if (!kprobe_optready(p) || !kprobes_allow_optimization ||
 614            (kprobe_disabled(p) || kprobes_all_disarmed))
 615                return;
 616
 617        /* Both of break_handler and post_handler are not supported. */
 618        if (p->break_handler || p->post_handler)
 619                return;
 620
 621        op = container_of(p, struct optimized_kprobe, kp);
 622
 623        /* Check there is no other kprobes at the optimized instructions */
 624        if (arch_check_optimized_kprobe(op) < 0)
 625                return;
 626
 627        /* Check if it is already optimized. */
 628        if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
 629                return;
 630        op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
 631
 632        if (!list_empty(&op->list))
 633                /* This is under unoptimizing. Just dequeue the probe */
 634                list_del_init(&op->list);
 635        else {
 636                list_add(&op->list, &optimizing_list);
 637                kick_kprobe_optimizer();
 638        }
 639}
 640
 641/* Short cut to direct unoptimizing */
 642static __kprobes void force_unoptimize_kprobe(struct optimized_kprobe *op)
 643{
 644        get_online_cpus();
 645        arch_unoptimize_kprobe(op);
 646        put_online_cpus();
 647        if (kprobe_disabled(&op->kp))
 648                arch_disarm_kprobe(&op->kp);
 649}
 650
 651/* Unoptimize a kprobe if p is optimized */
 652static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force)
 653{
 654        struct optimized_kprobe *op;
 655
 656        if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
 657                return; /* This is not an optprobe nor optimized */
 658
 659        op = container_of(p, struct optimized_kprobe, kp);
 660        if (!kprobe_optimized(p)) {
 661                /* Unoptimized or unoptimizing case */
 662                if (force && !list_empty(&op->list)) {
 663                        /*
 664                         * Only if this is unoptimizing kprobe and forced,
 665                         * forcibly unoptimize it. (No need to unoptimize
 666                         * unoptimized kprobe again :)
 667                         */
 668                        list_del_init(&op->list);
 669                        force_unoptimize_kprobe(op);
 670                }
 671                return;
 672        }
 673
 674        op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 675        if (!list_empty(&op->list)) {
 676                /* Dequeue from the optimization queue */
 677                list_del_init(&op->list);
 678                return;
 679        }
 680        /* Optimized kprobe case */
 681        if (force)
 682                /* Forcibly update the code: this is a special case */
 683                force_unoptimize_kprobe(op);
 684        else {
 685                list_add(&op->list, &unoptimizing_list);
 686                kick_kprobe_optimizer();
 687        }
 688}
 689
 690/* Cancel unoptimizing for reusing */
 691static void reuse_unused_kprobe(struct kprobe *ap)
 692{
 693        struct optimized_kprobe *op;
 694
 695        BUG_ON(!kprobe_unused(ap));
 696        /*
 697         * Unused kprobe MUST be on the way of delayed unoptimizing (means
 698         * there is still a relative jump) and disabled.
 699         */
 700        op = container_of(ap, struct optimized_kprobe, kp);
 701        if (unlikely(list_empty(&op->list)))
 702                printk(KERN_WARNING "Warning: found a stray unused "
 703                        "aggrprobe@%p\n", ap->addr);
 704        /* Enable the probe again */
 705        ap->flags &= ~KPROBE_FLAG_DISABLED;
 706        /* Optimize it again (remove from op->list) */
 707        BUG_ON(!kprobe_optready(ap));
 708        optimize_kprobe(ap);
 709}
 710
 711/* Remove optimized instructions */
 712static void __kprobes kill_optimized_kprobe(struct kprobe *p)
 713{
 714        struct optimized_kprobe *op;
 715
 716        op = container_of(p, struct optimized_kprobe, kp);
 717        if (!list_empty(&op->list))
 718                /* Dequeue from the (un)optimization queue */
 719                list_del_init(&op->list);
 720
 721        op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 722        /* Don't touch the code, because it is already freed. */
 723        arch_remove_optimized_kprobe(op);
 724}
 725
 726/* Try to prepare optimized instructions */
 727static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
 728{
 729        struct optimized_kprobe *op;
 730
 731        op = container_of(p, struct optimized_kprobe, kp);
 732        arch_prepare_optimized_kprobe(op);
 733}
 734
 735/* Allocate new optimized_kprobe and try to prepare optimized instructions */
 736static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 737{
 738        struct optimized_kprobe *op;
 739
 740        op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
 741        if (!op)
 742                return NULL;
 743
 744        INIT_LIST_HEAD(&op->list);
 745        op->kp.addr = p->addr;
 746        arch_prepare_optimized_kprobe(op);
 747
 748        return &op->kp;
 749}
 750
 751static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
 752
 753/*
 754 * Prepare an optimized_kprobe and optimize it
 755 * NOTE: p must be a normal registered kprobe
 756 */
 757static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
 758{
 759        struct kprobe *ap;
 760        struct optimized_kprobe *op;
 761
 762        ap = alloc_aggr_kprobe(p);
 763        if (!ap)
 764                return;
 765
 766        op = container_of(ap, struct optimized_kprobe, kp);
 767        if (!arch_prepared_optinsn(&op->optinsn)) {
 768                /* If failed to setup optimizing, fallback to kprobe */
 769                arch_remove_optimized_kprobe(op);
 770                kfree(op);
 771                return;
 772        }
 773
 774        init_aggr_kprobe(ap, p);
 775        optimize_kprobe(ap);
 776}
 777
 778#ifdef CONFIG_SYSCTL
 779/* This should be called with kprobe_mutex locked */
 780static void __kprobes optimize_all_kprobes(void)
 781{
 782        struct hlist_head *head;
 783        struct hlist_node *node;
 784        struct kprobe *p;
 785        unsigned int i;
 786
 787        /* If optimization is already allowed, just return */
 788        if (kprobes_allow_optimization)
 789                return;
 790
 791        kprobes_allow_optimization = true;
 792        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 793                head = &kprobe_table[i];
 794                hlist_for_each_entry_rcu(p, node, head, hlist)
 795                        if (!kprobe_disabled(p))
 796                                optimize_kprobe(p);
 797        }
 798        printk(KERN_INFO "Kprobes globally optimized\n");
 799}
 800
 801/* This should be called with kprobe_mutex locked */
 802static void __kprobes unoptimize_all_kprobes(void)
 803{
 804        struct hlist_head *head;
 805        struct hlist_node *node;
 806        struct kprobe *p;
 807        unsigned int i;
 808
 809        /* If optimization is already prohibited, just return */
 810        if (!kprobes_allow_optimization)
 811                return;
 812
 813        kprobes_allow_optimization = false;
 814        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 815                head = &kprobe_table[i];
 816                hlist_for_each_entry_rcu(p, node, head, hlist) {
 817                        if (!kprobe_disabled(p))
 818                                unoptimize_kprobe(p, false);
 819                }
 820        }
 821        /* Wait for unoptimizing completion */
 822        wait_for_kprobe_optimizer();
 823        printk(KERN_INFO "Kprobes globally unoptimized\n");
 824}
 825
 826int sysctl_kprobes_optimization;
 827int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
 828                                      void __user *buffer, size_t *length,
 829                                      loff_t *ppos)
 830{
 831        int ret;
 832
 833        mutex_lock(&kprobe_mutex);
 834        sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
 835        ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
 836
 837        if (sysctl_kprobes_optimization)
 838                optimize_all_kprobes();
 839        else
 840                unoptimize_all_kprobes();
 841        mutex_unlock(&kprobe_mutex);
 842
 843        return ret;
 844}
 845#endif /* CONFIG_SYSCTL */
 846
 847/* Put a breakpoint for a probe. Must be called with text_mutex locked */
 848static void __kprobes __arm_kprobe(struct kprobe *p)
 849{
 850        struct kprobe *_p;
 851
 852        /* Check collision with other optimized kprobes */
 853        _p = get_optimized_kprobe((unsigned long)p->addr);
 854        if (unlikely(_p))
 855                /* Fallback to unoptimized kprobe */
 856                unoptimize_kprobe(_p, true);
 857
 858        arch_arm_kprobe(p);
 859        optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
 860}
 861
 862/* Remove the breakpoint of a probe. Must be called with text_mutex locked */
 863static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt)
 864{
 865        struct kprobe *_p;
 866
 867        unoptimize_kprobe(p, false);    /* Try to unoptimize */
 868
 869        if (!kprobe_queued(p)) {
 870                arch_disarm_kprobe(p);
 871                /* If another kprobe was blocked, optimize it. */
 872                _p = get_optimized_kprobe((unsigned long)p->addr);
 873                if (unlikely(_p) && reopt)
 874                        optimize_kprobe(_p);
 875        }
 876        /* TODO: reoptimize others after unoptimized this probe */
 877}
 878
 879#else /* !CONFIG_OPTPROBES */
 880
 881#define optimize_kprobe(p)                      do {} while (0)
 882#define unoptimize_kprobe(p, f)                 do {} while (0)
 883#define kill_optimized_kprobe(p)                do {} while (0)
 884#define prepare_optimized_kprobe(p)             do {} while (0)
 885#define try_to_optimize_kprobe(p)               do {} while (0)
 886#define __arm_kprobe(p)                         arch_arm_kprobe(p)
 887#define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
 888#define kprobe_disarmed(p)                      kprobe_disabled(p)
 889#define wait_for_kprobe_optimizer()             do {} while (0)
 890
 891/* There should be no unused kprobes can be reused without optimization */
 892static void reuse_unused_kprobe(struct kprobe *ap)
 893{
 894        printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
 895        BUG_ON(kprobe_unused(ap));
 896}
 897
 898static __kprobes void free_aggr_kprobe(struct kprobe *p)
 899{
 900        arch_remove_kprobe(p);
 901        kfree(p);
 902}
 903
 904static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 905{
 906        return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
 907}
 908#endif /* CONFIG_OPTPROBES */
 909
 910/* Arm a kprobe with text_mutex */
 911static void __kprobes arm_kprobe(struct kprobe *kp)
 912{
 913        /*
 914         * Here, since __arm_kprobe() doesn't use stop_machine(),
 915         * this doesn't cause deadlock on text_mutex. So, we don't
 916         * need get_online_cpus().
 917         */
 918        mutex_lock(&text_mutex);
 919        __arm_kprobe(kp);
 920        mutex_unlock(&text_mutex);
 921}
 922
 923/* Disarm a kprobe with text_mutex */
 924static void __kprobes disarm_kprobe(struct kprobe *kp)
 925{
 926        /* Ditto */
 927        mutex_lock(&text_mutex);
 928        __disarm_kprobe(kp, true);
 929        mutex_unlock(&text_mutex);
 930}
 931
 932/*
 933 * Aggregate handlers for multiple kprobes support - these handlers
 934 * take care of invoking the individual kprobe handlers on p->list
 935 */
 936static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
 937{
 938        struct kprobe *kp;
 939
 940        list_for_each_entry_rcu(kp, &p->list, list) {
 941                if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 942                        set_kprobe_instance(kp);
 943                        if (kp->pre_handler(kp, regs))
 944                                return 1;
 945                }
 946                reset_kprobe_instance();
 947        }
 948        return 0;
 949}
 950
 951static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
 952                                        unsigned long flags)
 953{
 954        struct kprobe *kp;
 955
 956        list_for_each_entry_rcu(kp, &p->list, list) {
 957                if (kp->post_handler && likely(!kprobe_disabled(kp))) {
 958                        set_kprobe_instance(kp);
 959                        kp->post_handler(kp, regs, flags);
 960                        reset_kprobe_instance();
 961                }
 962        }
 963}
 964
 965static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
 966                                        int trapnr)
 967{
 968        struct kprobe *cur = __this_cpu_read(kprobe_instance);
 969
 970        /*
 971         * if we faulted "during" the execution of a user specified
 972         * probe handler, invoke just that probe's fault handler
 973         */
 974        if (cur && cur->fault_handler) {
 975                if (cur->fault_handler(cur, regs, trapnr))
 976                        return 1;
 977        }
 978        return 0;
 979}
 980
 981static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
 982{
 983        struct kprobe *cur = __this_cpu_read(kprobe_instance);
 984        int ret = 0;
 985
 986        if (cur && cur->break_handler) {
 987                if (cur->break_handler(cur, regs))
 988                        ret = 1;
 989        }
 990        reset_kprobe_instance();
 991        return ret;
 992}
 993
 994/* Walks the list and increments nmissed count for multiprobe case */
 995void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
 996{
 997        struct kprobe *kp;
 998        if (!kprobe_aggrprobe(p)) {
 999                p->nmissed++;
1000        } else {
1001                list_for_each_entry_rcu(kp, &p->list, list)
1002                        kp->nmissed++;
1003        }
1004        return;
1005}
1006
1007void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
1008                                struct hlist_head *head)
1009{
1010        struct kretprobe *rp = ri->rp;
1011
1012        /* remove rp inst off the rprobe_inst_table */
1013        hlist_del(&ri->hlist);
1014        INIT_HLIST_NODE(&ri->hlist);
1015        if (likely(rp)) {
1016                spin_lock(&rp->lock);
1017                hlist_add_head(&ri->hlist, &rp->free_instances);
1018                spin_unlock(&rp->lock);
1019        } else
1020                /* Unregistering */
1021                hlist_add_head(&ri->hlist, head);
1022}
1023
1024void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
1025                         struct hlist_head **head, unsigned long *flags)
1026__acquires(hlist_lock)
1027{
1028        unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1029        spinlock_t *hlist_lock;
1030
1031        *head = &kretprobe_inst_table[hash];
1032        hlist_lock = kretprobe_table_lock_ptr(hash);
1033        spin_lock_irqsave(hlist_lock, *flags);
1034}
1035
1036static void __kprobes kretprobe_table_lock(unsigned long hash,
1037        unsigned long *flags)
1038__acquires(hlist_lock)
1039{
1040        spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1041        spin_lock_irqsave(hlist_lock, *flags);
1042}
1043
1044void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
1045        unsigned long *flags)
1046__releases(hlist_lock)
1047{
1048        unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1049        spinlock_t *hlist_lock;
1050
1051        hlist_lock = kretprobe_table_lock_ptr(hash);
1052        spin_unlock_irqrestore(hlist_lock, *flags);
1053}
1054
1055static void __kprobes kretprobe_table_unlock(unsigned long hash,
1056       unsigned long *flags)
1057__releases(hlist_lock)
1058{
1059        spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1060        spin_unlock_irqrestore(hlist_lock, *flags);
1061}
1062
1063/*
1064 * This function is called from finish_task_switch when task tk becomes dead,
1065 * so that we can recycle any function-return probe instances associated
1066 * with this task. These left over instances represent probed functions
1067 * that have been called but will never return.
1068 */
1069void __kprobes kprobe_flush_task(struct task_struct *tk)
1070{
1071        struct kretprobe_instance *ri;
1072        struct hlist_head *head, empty_rp;
1073        struct hlist_node *node, *tmp;
1074        unsigned long hash, flags = 0;
1075
1076        if (unlikely(!kprobes_initialized))
1077                /* Early boot.  kretprobe_table_locks not yet initialized. */
1078                return;
1079
1080        hash = hash_ptr(tk, KPROBE_HASH_BITS);
1081        head = &kretprobe_inst_table[hash];
1082        kretprobe_table_lock(hash, &flags);
1083        hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
1084                if (ri->task == tk)
1085                        recycle_rp_inst(ri, &empty_rp);
1086        }
1087        kretprobe_table_unlock(hash, &flags);
1088        INIT_HLIST_HEAD(&empty_rp);
1089        hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
1090                hlist_del(&ri->hlist);
1091                kfree(ri);
1092        }
1093}
1094
1095static inline void free_rp_inst(struct kretprobe *rp)
1096{
1097        struct kretprobe_instance *ri;
1098        struct hlist_node *pos, *next;
1099
1100        hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
1101                hlist_del(&ri->hlist);
1102                kfree(ri);
1103        }
1104}
1105
1106static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
1107{
1108        unsigned long flags, hash;
1109        struct kretprobe_instance *ri;
1110        struct hlist_node *pos, *next;
1111        struct hlist_head *head;
1112
1113        /* No race here */
1114        for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1115                kretprobe_table_lock(hash, &flags);
1116                head = &kretprobe_inst_table[hash];
1117                hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
1118                        if (ri->rp == rp)
1119                                ri->rp = NULL;
1120                }
1121                kretprobe_table_unlock(hash, &flags);
1122        }
1123        free_rp_inst(rp);
1124}
1125
1126/*
1127* Add the new probe to ap->list. Fail if this is the
1128* second jprobe at the address - two jprobes can't coexist
1129*/
1130static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1131{
1132        BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1133
1134        if (p->break_handler || p->post_handler)
1135                unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1136
1137        if (p->break_handler) {
1138                if (ap->break_handler)
1139                        return -EEXIST;
1140                list_add_tail_rcu(&p->list, &ap->list);
1141                ap->break_handler = aggr_break_handler;
1142        } else
1143                list_add_rcu(&p->list, &ap->list);
1144        if (p->post_handler && !ap->post_handler)
1145                ap->post_handler = aggr_post_handler;
1146
1147        if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
1148                ap->flags &= ~KPROBE_FLAG_DISABLED;
1149                if (!kprobes_all_disarmed)
1150                        /* Arm the breakpoint again. */
1151                        __arm_kprobe(ap);
1152        }
1153        return 0;
1154}
1155
1156/*
1157 * Fill in the required fields of the "manager kprobe". Replace the
1158 * earlier kprobe in the hlist with the manager kprobe
1159 */
1160static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1161{
1162        /* Copy p's insn slot to ap */
1163        copy_kprobe(p, ap);
1164        flush_insn_slot(ap);
1165        ap->addr = p->addr;
1166        ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1167        ap->pre_handler = aggr_pre_handler;
1168        ap->fault_handler = aggr_fault_handler;
1169        /* We don't care the kprobe which has gone. */
1170        if (p->post_handler && !kprobe_gone(p))
1171                ap->post_handler = aggr_post_handler;
1172        if (p->break_handler && !kprobe_gone(p))
1173                ap->break_handler = aggr_break_handler;
1174
1175        INIT_LIST_HEAD(&ap->list);
1176        INIT_HLIST_NODE(&ap->hlist);
1177
1178        list_add_rcu(&p->list, &ap->list);
1179        hlist_replace_rcu(&p->hlist, &ap->hlist);
1180}
1181
1182/*
1183 * This is the second or subsequent kprobe at the address - handle
1184 * the intricacies
1185 */
1186static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
1187                                          struct kprobe *p)
1188{
1189        int ret = 0;
1190        struct kprobe *ap = orig_p;
1191
1192        if (!kprobe_aggrprobe(orig_p)) {
1193                /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1194                ap = alloc_aggr_kprobe(orig_p);
1195                if (!ap)
1196                        return -ENOMEM;
1197                init_aggr_kprobe(ap, orig_p);
1198        } else if (kprobe_unused(ap))
1199                /* This probe is going to die. Rescue it */
1200                reuse_unused_kprobe(ap);
1201
1202        if (kprobe_gone(ap)) {
1203                /*
1204                 * Attempting to insert new probe at the same location that
1205                 * had a probe in the module vaddr area which already
1206                 * freed. So, the instruction slot has already been
1207                 * released. We need a new slot for the new probe.
1208                 */
1209                ret = arch_prepare_kprobe(ap);
1210                if (ret)
1211                        /*
1212                         * Even if fail to allocate new slot, don't need to
1213                         * free aggr_probe. It will be used next time, or
1214                         * freed by unregister_kprobe.
1215                         */
1216                        return ret;
1217
1218                /* Prepare optimized instructions if possible. */
1219                prepare_optimized_kprobe(ap);
1220
1221                /*
1222                 * Clear gone flag to prevent allocating new slot again, and
1223                 * set disabled flag because it is not armed yet.
1224                 */
1225                ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1226                            | KPROBE_FLAG_DISABLED;
1227        }
1228
1229        /* Copy ap's insn slot to p */
1230        copy_kprobe(ap, p);
1231        return add_new_kprobe(ap, p);
1232}
1233
1234static int __kprobes in_kprobes_functions(unsigned long addr)
1235{
1236        struct kprobe_blackpoint *kb;
1237
1238        if (addr >= (unsigned long)__kprobes_text_start &&
1239            addr < (unsigned long)__kprobes_text_end)
1240                return -EINVAL;
1241        /*
1242         * If there exists a kprobe_blacklist, verify and
1243         * fail any probe registration in the prohibited area
1244         */
1245        for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1246                if (kb->start_addr) {
1247                        if (addr >= kb->start_addr &&
1248                            addr < (kb->start_addr + kb->range))
1249                                return -EINVAL;
1250                }
1251        }
1252        return 0;
1253}
1254
1255/*
1256 * If we have a symbol_name argument, look it up and add the offset field
1257 * to it. This way, we can specify a relative address to a symbol.
1258 * This returns encoded errors if it fails to look up symbol or invalid
1259 * combination of parameters.
1260 */
1261static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
1262{
1263        kprobe_opcode_t *addr = p->addr;
1264
1265        if ((p->symbol_name && p->addr) ||
1266            (!p->symbol_name && !p->addr))
1267                goto invalid;
1268
1269        if (p->symbol_name) {
1270                kprobe_lookup_name(p->symbol_name, addr);
1271                if (!addr)
1272                        return ERR_PTR(-ENOENT);
1273        }
1274
1275        addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1276        if (addr)
1277                return addr;
1278
1279invalid:
1280        return ERR_PTR(-EINVAL);
1281}
1282
1283/* Check passed kprobe is valid and return kprobe in kprobe_table. */
1284static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
1285{
1286        struct kprobe *ap, *list_p;
1287
1288        ap = get_kprobe(p->addr);
1289        if (unlikely(!ap))
1290                return NULL;
1291
1292        if (p != ap) {
1293                list_for_each_entry_rcu(list_p, &ap->list, list)
1294                        if (list_p == p)
1295                        /* kprobe p is a valid probe */
1296                                goto valid;
1297                return NULL;
1298        }
1299valid:
1300        return ap;
1301}
1302
1303/* Return error if the kprobe is being re-registered */
1304static inline int check_kprobe_rereg(struct kprobe *p)
1305{
1306        int ret = 0;
1307
1308        mutex_lock(&kprobe_mutex);
1309        if (__get_valid_kprobe(p))
1310                ret = -EINVAL;
1311        mutex_unlock(&kprobe_mutex);
1312
1313        return ret;
1314}
1315
1316int __kprobes register_kprobe(struct kprobe *p)
1317{
1318        int ret = 0;
1319        struct kprobe *old_p;
1320        struct module *probed_mod;
1321        kprobe_opcode_t *addr;
1322
1323        addr = kprobe_addr(p);
1324        if (IS_ERR(addr))
1325                return PTR_ERR(addr);
1326        p->addr = addr;
1327
1328        ret = check_kprobe_rereg(p);
1329        if (ret)
1330                return ret;
1331
1332        jump_label_lock();
1333        preempt_disable();
1334        if (!kernel_text_address((unsigned long) p->addr) ||
1335            in_kprobes_functions((unsigned long) p->addr) ||
1336            ftrace_text_reserved(p->addr, p->addr) ||
1337            jump_label_text_reserved(p->addr, p->addr))
1338                goto fail_with_jump_label;
1339
1340        /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1341        p->flags &= KPROBE_FLAG_DISABLED;
1342
1343        /*
1344         * Check if are we probing a module.
1345         */
1346        probed_mod = __module_text_address((unsigned long) p->addr);
1347        if (probed_mod) {
1348                /* Return -ENOENT if fail. */
1349                ret = -ENOENT;
1350                /*
1351                 * We must hold a refcount of the probed module while updating
1352                 * its code to prohibit unexpected unloading.
1353                 */
1354                if (unlikely(!try_module_get(probed_mod)))
1355                        goto fail_with_jump_label;
1356
1357                /*
1358                 * If the module freed .init.text, we couldn't insert
1359                 * kprobes in there.
1360                 */
1361                if (within_module_init((unsigned long)p->addr, probed_mod) &&
1362                    probed_mod->state != MODULE_STATE_COMING) {
1363                        module_put(probed_mod);
1364                        goto fail_with_jump_label;
1365                }
1366                /* ret will be updated by following code */
1367        }
1368        preempt_enable();
1369        jump_label_unlock();
1370
1371        p->nmissed = 0;
1372        INIT_LIST_HEAD(&p->list);
1373        mutex_lock(&kprobe_mutex);
1374
1375        jump_label_lock(); /* needed to call jump_label_text_reserved() */
1376
1377        get_online_cpus();      /* For avoiding text_mutex deadlock. */
1378        mutex_lock(&text_mutex);
1379
1380        old_p = get_kprobe(p->addr);
1381        if (old_p) {
1382                /* Since this may unoptimize old_p, locking text_mutex. */
1383                ret = register_aggr_kprobe(old_p, p);
1384                goto out;
1385        }
1386
1387        ret = arch_prepare_kprobe(p);
1388        if (ret)
1389                goto out;
1390
1391        INIT_HLIST_NODE(&p->hlist);
1392        hlist_add_head_rcu(&p->hlist,
1393                       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1394
1395        if (!kprobes_all_disarmed && !kprobe_disabled(p))
1396                __arm_kprobe(p);
1397
1398        /* Try to optimize kprobe */
1399        try_to_optimize_kprobe(p);
1400
1401out:
1402        mutex_unlock(&text_mutex);
1403        put_online_cpus();
1404        jump_label_unlock();
1405        mutex_unlock(&kprobe_mutex);
1406
1407        if (probed_mod)
1408                module_put(probed_mod);
1409
1410        return ret;
1411
1412fail_with_jump_label:
1413        preempt_enable();
1414        jump_label_unlock();
1415        return ret;
1416}
1417EXPORT_SYMBOL_GPL(register_kprobe);
1418
1419/* Check if all probes on the aggrprobe are disabled */
1420static int __kprobes aggr_kprobe_disabled(struct kprobe *ap)
1421{
1422        struct kprobe *kp;
1423
1424        list_for_each_entry_rcu(kp, &ap->list, list)
1425                if (!kprobe_disabled(kp))
1426                        /*
1427                         * There is an active probe on the list.
1428                         * We can't disable this ap.
1429                         */
1430                        return 0;
1431
1432        return 1;
1433}
1434
1435/* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1436static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
1437{
1438        struct kprobe *orig_p;
1439
1440        /* Get an original kprobe for return */
1441        orig_p = __get_valid_kprobe(p);
1442        if (unlikely(orig_p == NULL))
1443                return NULL;
1444
1445        if (!kprobe_disabled(p)) {
1446                /* Disable probe if it is a child probe */
1447                if (p != orig_p)
1448                        p->flags |= KPROBE_FLAG_DISABLED;
1449
1450                /* Try to disarm and disable this/parent probe */
1451                if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1452                        disarm_kprobe(orig_p);
1453                        orig_p->flags |= KPROBE_FLAG_DISABLED;
1454                }
1455        }
1456
1457        return orig_p;
1458}
1459
1460/*
1461 * Unregister a kprobe without a scheduler synchronization.
1462 */
1463static int __kprobes __unregister_kprobe_top(struct kprobe *p)
1464{
1465        struct kprobe *ap, *list_p;
1466
1467        /* Disable kprobe. This will disarm it if needed. */
1468        ap = __disable_kprobe(p);
1469        if (ap == NULL)
1470                return -EINVAL;
1471
1472        if (ap == p)
1473                /*
1474                 * This probe is an independent(and non-optimized) kprobe
1475                 * (not an aggrprobe). Remove from the hash list.
1476                 */
1477                goto disarmed;
1478
1479        /* Following process expects this probe is an aggrprobe */
1480        WARN_ON(!kprobe_aggrprobe(ap));
1481
1482        if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1483                /*
1484                 * !disarmed could be happen if the probe is under delayed
1485                 * unoptimizing.
1486                 */
1487                goto disarmed;
1488        else {
1489                /* If disabling probe has special handlers, update aggrprobe */
1490                if (p->break_handler && !kprobe_gone(p))
1491                        ap->break_handler = NULL;
1492                if (p->post_handler && !kprobe_gone(p)) {
1493                        list_for_each_entry_rcu(list_p, &ap->list, list) {
1494                                if ((list_p != p) && (list_p->post_handler))
1495                                        goto noclean;
1496                        }
1497                        ap->post_handler = NULL;
1498                }
1499noclean:
1500                /*
1501                 * Remove from the aggrprobe: this path will do nothing in
1502                 * __unregister_kprobe_bottom().
1503                 */
1504                list_del_rcu(&p->list);
1505                if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1506                        /*
1507                         * Try to optimize this probe again, because post
1508                         * handler may have been changed.
1509                         */
1510                        optimize_kprobe(ap);
1511        }
1512        return 0;
1513
1514disarmed:
1515        BUG_ON(!kprobe_disarmed(ap));
1516        hlist_del_rcu(&ap->hlist);
1517        return 0;
1518}
1519
1520static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
1521{
1522        struct kprobe *ap;
1523
1524        if (list_empty(&p->list))
1525                /* This is an independent kprobe */
1526                arch_remove_kprobe(p);
1527        else if (list_is_singular(&p->list)) {
1528                /* This is the last child of an aggrprobe */
1529                ap = list_entry(p->list.next, struct kprobe, list);
1530                list_del(&p->list);
1531                free_aggr_kprobe(ap);
1532        }
1533        /* Otherwise, do nothing. */
1534}
1535
1536int __kprobes register_kprobes(struct kprobe **kps, int num)
1537{
1538        int i, ret = 0;
1539
1540        if (num <= 0)
1541                return -EINVAL;
1542        for (i = 0; i < num; i++) {
1543                ret = register_kprobe(kps[i]);
1544                if (ret < 0) {
1545                        if (i > 0)
1546                                unregister_kprobes(kps, i);
1547                        break;
1548                }
1549        }
1550        return ret;
1551}
1552EXPORT_SYMBOL_GPL(register_kprobes);
1553
1554void __kprobes unregister_kprobe(struct kprobe *p)
1555{
1556        unregister_kprobes(&p, 1);
1557}
1558EXPORT_SYMBOL_GPL(unregister_kprobe);
1559
1560void __kprobes unregister_kprobes(struct kprobe **kps, int num)
1561{
1562        int i;
1563
1564        if (num <= 0)
1565                return;
1566        mutex_lock(&kprobe_mutex);
1567        for (i = 0; i < num; i++)
1568                if (__unregister_kprobe_top(kps[i]) < 0)
1569                        kps[i]->addr = NULL;
1570        mutex_unlock(&kprobe_mutex);
1571
1572        synchronize_sched();
1573        for (i = 0; i < num; i++)
1574                if (kps[i]->addr)
1575                        __unregister_kprobe_bottom(kps[i]);
1576}
1577EXPORT_SYMBOL_GPL(unregister_kprobes);
1578
1579static struct notifier_block kprobe_exceptions_nb = {
1580        .notifier_call = kprobe_exceptions_notify,
1581        .priority = 0x7fffffff /* we need to be notified first */
1582};
1583
1584unsigned long __weak arch_deref_entry_point(void *entry)
1585{
1586        return (unsigned long)entry;
1587}
1588
1589int __kprobes register_jprobes(struct jprobe **jps, int num)
1590{
1591        struct jprobe *jp;
1592        int ret = 0, i;
1593
1594        if (num <= 0)
1595                return -EINVAL;
1596        for (i = 0; i < num; i++) {
1597                unsigned long addr, offset;
1598                jp = jps[i];
1599                addr = arch_deref_entry_point(jp->entry);
1600
1601                /* Verify probepoint is a function entry point */
1602                if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1603                    offset == 0) {
1604                        jp->kp.pre_handler = setjmp_pre_handler;
1605                        jp->kp.break_handler = longjmp_break_handler;
1606                        ret = register_kprobe(&jp->kp);
1607                } else
1608                        ret = -EINVAL;
1609
1610                if (ret < 0) {
1611                        if (i > 0)
1612                                unregister_jprobes(jps, i);
1613                        break;
1614                }
1615        }
1616        return ret;
1617}
1618EXPORT_SYMBOL_GPL(register_jprobes);
1619
1620int __kprobes register_jprobe(struct jprobe *jp)
1621{
1622        return register_jprobes(&jp, 1);
1623}
1624EXPORT_SYMBOL_GPL(register_jprobe);
1625
1626void __kprobes unregister_jprobe(struct jprobe *jp)
1627{
1628        unregister_jprobes(&jp, 1);
1629}
1630EXPORT_SYMBOL_GPL(unregister_jprobe);
1631
1632void __kprobes unregister_jprobes(struct jprobe **jps, int num)
1633{
1634        int i;
1635
1636        if (num <= 0)
1637                return;
1638        mutex_lock(&kprobe_mutex);
1639        for (i = 0; i < num; i++)
1640                if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1641                        jps[i]->kp.addr = NULL;
1642        mutex_unlock(&kprobe_mutex);
1643
1644        synchronize_sched();
1645        for (i = 0; i < num; i++) {
1646                if (jps[i]->kp.addr)
1647                        __unregister_kprobe_bottom(&jps[i]->kp);
1648        }
1649}
1650EXPORT_SYMBOL_GPL(unregister_jprobes);
1651
1652#ifdef CONFIG_KRETPROBES
1653/*
1654 * This kprobe pre_handler is registered with every kretprobe. When probe
1655 * hits it will set up the return probe.
1656 */
1657static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1658                                           struct pt_regs *regs)
1659{
1660        struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1661        unsigned long hash, flags = 0;
1662        struct kretprobe_instance *ri;
1663
1664        /*TODO: consider to only swap the RA after the last pre_handler fired */
1665        hash = hash_ptr(current, KPROBE_HASH_BITS);
1666        spin_lock_irqsave(&rp->lock, flags);
1667        if (!hlist_empty(&rp->free_instances)) {
1668                ri = hlist_entry(rp->free_instances.first,
1669                                struct kretprobe_instance, hlist);
1670                hlist_del(&ri->hlist);
1671                spin_unlock_irqrestore(&rp->lock, flags);
1672
1673                ri->rp = rp;
1674                ri->task = current;
1675
1676                if (rp->entry_handler && rp->entry_handler(ri, regs))
1677                        return 0;
1678
1679                arch_prepare_kretprobe(ri, regs);
1680
1681                /* XXX(hch): why is there no hlist_move_head? */
1682                INIT_HLIST_NODE(&ri->hlist);
1683                kretprobe_table_lock(hash, &flags);
1684                hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1685                kretprobe_table_unlock(hash, &flags);
1686        } else {
1687                rp->nmissed++;
1688                spin_unlock_irqrestore(&rp->lock, flags);
1689        }
1690        return 0;
1691}
1692
1693int __kprobes register_kretprobe(struct kretprobe *rp)
1694{
1695        int ret = 0;
1696        struct kretprobe_instance *inst;
1697        int i;
1698        void *addr;
1699
1700        if (kretprobe_blacklist_size) {
1701                addr = kprobe_addr(&rp->kp);
1702                if (IS_ERR(addr))
1703                        return PTR_ERR(addr);
1704
1705                for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1706                        if (kretprobe_blacklist[i].addr == addr)
1707                                return -EINVAL;
1708                }
1709        }
1710
1711        rp->kp.pre_handler = pre_handler_kretprobe;
1712        rp->kp.post_handler = NULL;
1713        rp->kp.fault_handler = NULL;
1714        rp->kp.break_handler = NULL;
1715
1716        /* Pre-allocate memory for max kretprobe instances */
1717        if (rp->maxactive <= 0) {
1718#ifdef CONFIG_PREEMPT
1719                rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1720#else
1721                rp->maxactive = num_possible_cpus();
1722#endif
1723        }
1724        spin_lock_init(&rp->lock);
1725        INIT_HLIST_HEAD(&rp->free_instances);
1726        for (i = 0; i < rp->maxactive; i++) {
1727                inst = kmalloc(sizeof(struct kretprobe_instance) +
1728                               rp->data_size, GFP_KERNEL);
1729                if (inst == NULL) {
1730                        free_rp_inst(rp);
1731                        return -ENOMEM;
1732                }
1733                INIT_HLIST_NODE(&inst->hlist);
1734                hlist_add_head(&inst->hlist, &rp->free_instances);
1735        }
1736
1737        rp->nmissed = 0;
1738        /* Establish function entry probe point */
1739        ret = register_kprobe(&rp->kp);
1740        if (ret != 0)
1741                free_rp_inst(rp);
1742        return ret;
1743}
1744EXPORT_SYMBOL_GPL(register_kretprobe);
1745
1746int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1747{
1748        int ret = 0, i;
1749
1750        if (num <= 0)
1751                return -EINVAL;
1752        for (i = 0; i < num; i++) {
1753                ret = register_kretprobe(rps[i]);
1754                if (ret < 0) {
1755                        if (i > 0)
1756                                unregister_kretprobes(rps, i);
1757                        break;
1758                }
1759        }
1760        return ret;
1761}
1762EXPORT_SYMBOL_GPL(register_kretprobes);
1763
1764void __kprobes unregister_kretprobe(struct kretprobe *rp)
1765{
1766        unregister_kretprobes(&rp, 1);
1767}
1768EXPORT_SYMBOL_GPL(unregister_kretprobe);
1769
1770void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1771{
1772        int i;
1773
1774        if (num <= 0)
1775                return;
1776        mutex_lock(&kprobe_mutex);
1777        for (i = 0; i < num; i++)
1778                if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1779                        rps[i]->kp.addr = NULL;
1780        mutex_unlock(&kprobe_mutex);
1781
1782        synchronize_sched();
1783        for (i = 0; i < num; i++) {
1784                if (rps[i]->kp.addr) {
1785                        __unregister_kprobe_bottom(&rps[i]->kp);
1786                        cleanup_rp_inst(rps[i]);
1787                }
1788        }
1789}
1790EXPORT_SYMBOL_GPL(unregister_kretprobes);
1791
1792#else /* CONFIG_KRETPROBES */
1793int __kprobes register_kretprobe(struct kretprobe *rp)
1794{
1795        return -ENOSYS;
1796}
1797EXPORT_SYMBOL_GPL(register_kretprobe);
1798
1799int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1800{
1801        return -ENOSYS;
1802}
1803EXPORT_SYMBOL_GPL(register_kretprobes);
1804
1805void __kprobes unregister_kretprobe(struct kretprobe *rp)
1806{
1807}
1808EXPORT_SYMBOL_GPL(unregister_kretprobe);
1809
1810void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1811{
1812}
1813EXPORT_SYMBOL_GPL(unregister_kretprobes);
1814
1815static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1816                                           struct pt_regs *regs)
1817{
1818        return 0;
1819}
1820
1821#endif /* CONFIG_KRETPROBES */
1822
1823/* Set the kprobe gone and remove its instruction buffer. */
1824static void __kprobes kill_kprobe(struct kprobe *p)
1825{
1826        struct kprobe *kp;
1827
1828        p->flags |= KPROBE_FLAG_GONE;
1829        if (kprobe_aggrprobe(p)) {
1830                /*
1831                 * If this is an aggr_kprobe, we have to list all the
1832                 * chained probes and mark them GONE.
1833                 */
1834                list_for_each_entry_rcu(kp, &p->list, list)
1835                        kp->flags |= KPROBE_FLAG_GONE;
1836                p->post_handler = NULL;
1837                p->break_handler = NULL;
1838                kill_optimized_kprobe(p);
1839        }
1840        /*
1841         * Here, we can remove insn_slot safely, because no thread calls
1842         * the original probed function (which will be freed soon) any more.
1843         */
1844        arch_remove_kprobe(p);
1845}
1846
1847/* Disable one kprobe */
1848int __kprobes disable_kprobe(struct kprobe *kp)
1849{
1850        int ret = 0;
1851
1852        mutex_lock(&kprobe_mutex);
1853
1854        /* Disable this kprobe */
1855        if (__disable_kprobe(kp) == NULL)
1856                ret = -EINVAL;
1857
1858        mutex_unlock(&kprobe_mutex);
1859        return ret;
1860}
1861EXPORT_SYMBOL_GPL(disable_kprobe);
1862
1863/* Enable one kprobe */
1864int __kprobes enable_kprobe(struct kprobe *kp)
1865{
1866        int ret = 0;
1867        struct kprobe *p;
1868
1869        mutex_lock(&kprobe_mutex);
1870
1871        /* Check whether specified probe is valid. */
1872        p = __get_valid_kprobe(kp);
1873        if (unlikely(p == NULL)) {
1874                ret = -EINVAL;
1875                goto out;
1876        }
1877
1878        if (kprobe_gone(kp)) {
1879                /* This kprobe has gone, we couldn't enable it. */
1880                ret = -EINVAL;
1881                goto out;
1882        }
1883
1884        if (p != kp)
1885                kp->flags &= ~KPROBE_FLAG_DISABLED;
1886
1887        if (!kprobes_all_disarmed && kprobe_disabled(p)) {
1888                p->flags &= ~KPROBE_FLAG_DISABLED;
1889                arm_kprobe(p);
1890        }
1891out:
1892        mutex_unlock(&kprobe_mutex);
1893        return ret;
1894}
1895EXPORT_SYMBOL_GPL(enable_kprobe);
1896
1897void __kprobes dump_kprobe(struct kprobe *kp)
1898{
1899        printk(KERN_WARNING "Dumping kprobe:\n");
1900        printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
1901               kp->symbol_name, kp->addr, kp->offset);
1902}
1903
1904/* Module notifier call back, checking kprobes on the module */
1905static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1906                                             unsigned long val, void *data)
1907{
1908        struct module *mod = data;
1909        struct hlist_head *head;
1910        struct hlist_node *node;
1911        struct kprobe *p;
1912        unsigned int i;
1913        int checkcore = (val == MODULE_STATE_GOING);
1914
1915        if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1916                return NOTIFY_DONE;
1917
1918        /*
1919         * When MODULE_STATE_GOING was notified, both of module .text and
1920         * .init.text sections would be freed. When MODULE_STATE_LIVE was
1921         * notified, only .init.text section would be freed. We need to
1922         * disable kprobes which have been inserted in the sections.
1923         */
1924        mutex_lock(&kprobe_mutex);
1925        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1926                head = &kprobe_table[i];
1927                hlist_for_each_entry_rcu(p, node, head, hlist)
1928                        if (within_module_init((unsigned long)p->addr, mod) ||
1929                            (checkcore &&
1930                             within_module_core((unsigned long)p->addr, mod))) {
1931                                /*
1932                                 * The vaddr this probe is installed will soon
1933                                 * be vfreed buy not synced to disk. Hence,
1934                                 * disarming the breakpoint isn't needed.
1935                                 */
1936                                kill_kprobe(p);
1937                        }
1938        }
1939        mutex_unlock(&kprobe_mutex);
1940        return NOTIFY_DONE;
1941}
1942
1943static struct notifier_block kprobe_module_nb = {
1944        .notifier_call = kprobes_module_callback,
1945        .priority = 0
1946};
1947
1948static int __init init_kprobes(void)
1949{
1950        int i, err = 0;
1951        unsigned long offset = 0, size = 0;
1952        char *modname, namebuf[128];
1953        const char *symbol_name;
1954        void *addr;
1955        struct kprobe_blackpoint *kb;
1956
1957        /* FIXME allocate the probe table, currently defined statically */
1958        /* initialize all list heads */
1959        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1960                INIT_HLIST_HEAD(&kprobe_table[i]);
1961                INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1962                spin_lock_init(&(kretprobe_table_locks[i].lock));
1963        }
1964
1965        /*
1966         * Lookup and populate the kprobe_blacklist.
1967         *
1968         * Unlike the kretprobe blacklist, we'll need to determine
1969         * the range of addresses that belong to the said functions,
1970         * since a kprobe need not necessarily be at the beginning
1971         * of a function.
1972         */
1973        for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1974                kprobe_lookup_name(kb->name, addr);
1975                if (!addr)
1976                        continue;
1977
1978                kb->start_addr = (unsigned long)addr;
1979                symbol_name = kallsyms_lookup(kb->start_addr,
1980                                &size, &offset, &modname, namebuf);
1981                if (!symbol_name)
1982                        kb->range = 0;
1983                else
1984                        kb->range = size;
1985        }
1986
1987        if (kretprobe_blacklist_size) {
1988                /* lookup the function address from its name */
1989                for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1990                        kprobe_lookup_name(kretprobe_blacklist[i].name,
1991                                           kretprobe_blacklist[i].addr);
1992                        if (!kretprobe_blacklist[i].addr)
1993                                printk("kretprobe: lookup failed: %s\n",
1994                                       kretprobe_blacklist[i].name);
1995                }
1996        }
1997
1998#if defined(CONFIG_OPTPROBES)
1999#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2000        /* Init kprobe_optinsn_slots */
2001        kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2002#endif
2003        /* By default, kprobes can be optimized */
2004        kprobes_allow_optimization = true;
2005#endif
2006
2007        /* By default, kprobes are armed */
2008        kprobes_all_disarmed = false;
2009
2010        err = arch_init_kprobes();
2011        if (!err)
2012                err = register_die_notifier(&kprobe_exceptions_nb);
2013        if (!err)
2014                err = register_module_notifier(&kprobe_module_nb);
2015
2016        kprobes_initialized = (err == 0);
2017
2018        if (!err)
2019                init_test_probes();
2020        return err;
2021}
2022
2023#ifdef CONFIG_DEBUG_FS
2024static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
2025                const char *sym, int offset, char *modname, struct kprobe *pp)
2026{
2027        char *kprobe_type;
2028
2029        if (p->pre_handler == pre_handler_kretprobe)
2030                kprobe_type = "r";
2031        else if (p->pre_handler == setjmp_pre_handler)
2032                kprobe_type = "j";
2033        else
2034                kprobe_type = "k";
2035
2036        if (sym)
2037                seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2038                        p->addr, kprobe_type, sym, offset,
2039                        (modname ? modname : " "));
2040        else
2041                seq_printf(pi, "%p  %s  %p ",
2042                        p->addr, kprobe_type, p->addr);
2043
2044        if (!pp)
2045                pp = p;
2046        seq_printf(pi, "%s%s%s\n",
2047                (kprobe_gone(p) ? "[GONE]" : ""),
2048                ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2049                (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""));
2050}
2051
2052static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2053{
2054        return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2055}
2056
2057static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2058{
2059        (*pos)++;
2060        if (*pos >= KPROBE_TABLE_SIZE)
2061                return NULL;
2062        return pos;
2063}
2064
2065static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
2066{
2067        /* Nothing to do */
2068}
2069
2070static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
2071{
2072        struct hlist_head *head;
2073        struct hlist_node *node;
2074        struct kprobe *p, *kp;
2075        const char *sym = NULL;
2076        unsigned int i = *(loff_t *) v;
2077        unsigned long offset = 0;
2078        char *modname, namebuf[128];
2079
2080        head = &kprobe_table[i];
2081        preempt_disable();
2082        hlist_for_each_entry_rcu(p, node, head, hlist) {
2083                sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2084                                        &offset, &modname, namebuf);
2085                if (kprobe_aggrprobe(p)) {
2086                        list_for_each_entry_rcu(kp, &p->list, list)
2087                                report_probe(pi, kp, sym, offset, modname, p);
2088                } else
2089                        report_probe(pi, p, sym, offset, modname, NULL);
2090        }
2091        preempt_enable();
2092        return 0;
2093}
2094
2095static const struct seq_operations kprobes_seq_ops = {
2096        .start = kprobe_seq_start,
2097        .next  = kprobe_seq_next,
2098        .stop  = kprobe_seq_stop,
2099        .show  = show_kprobe_addr
2100};
2101
2102static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
2103{
2104        return seq_open(filp, &kprobes_seq_ops);
2105}
2106
2107static const struct file_operations debugfs_kprobes_operations = {
2108        .open           = kprobes_open,
2109        .read           = seq_read,
2110        .llseek         = seq_lseek,
2111        .release        = seq_release,
2112};
2113
2114static void __kprobes arm_all_kprobes(void)
2115{
2116        struct hlist_head *head;
2117        struct hlist_node *node;
2118        struct kprobe *p;
2119        unsigned int i;
2120
2121        mutex_lock(&kprobe_mutex);
2122
2123        /* If kprobes are armed, just return */
2124        if (!kprobes_all_disarmed)
2125                goto already_enabled;
2126
2127        /* Arming kprobes doesn't optimize kprobe itself */
2128        mutex_lock(&text_mutex);
2129        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2130                head = &kprobe_table[i];
2131                hlist_for_each_entry_rcu(p, node, head, hlist)
2132                        if (!kprobe_disabled(p))
2133                                __arm_kprobe(p);
2134        }
2135        mutex_unlock(&text_mutex);
2136
2137        kprobes_all_disarmed = false;
2138        printk(KERN_INFO "Kprobes globally enabled\n");
2139
2140already_enabled:
2141        mutex_unlock(&kprobe_mutex);
2142        return;
2143}
2144
2145static void __kprobes disarm_all_kprobes(void)
2146{
2147        struct hlist_head *head;
2148        struct hlist_node *node;
2149        struct kprobe *p;
2150        unsigned int i;
2151
2152        mutex_lock(&kprobe_mutex);
2153
2154        /* If kprobes are already disarmed, just return */
2155        if (kprobes_all_disarmed) {
2156                mutex_unlock(&kprobe_mutex);
2157                return;
2158        }
2159
2160        kprobes_all_disarmed = true;
2161        printk(KERN_INFO "Kprobes globally disabled\n");
2162
2163        mutex_lock(&text_mutex);
2164        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2165                head = &kprobe_table[i];
2166                hlist_for_each_entry_rcu(p, node, head, hlist) {
2167                        if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2168                                __disarm_kprobe(p, false);
2169                }
2170        }
2171        mutex_unlock(&text_mutex);
2172        mutex_unlock(&kprobe_mutex);
2173
2174        /* Wait for disarming all kprobes by optimizer */
2175        wait_for_kprobe_optimizer();
2176}
2177
2178/*
2179 * XXX: The debugfs bool file interface doesn't allow for callbacks
2180 * when the bool state is switched. We can reuse that facility when
2181 * available
2182 */
2183static ssize_t read_enabled_file_bool(struct file *file,
2184               char __user *user_buf, size_t count, loff_t *ppos)
2185{
2186        char buf[3];
2187
2188        if (!kprobes_all_disarmed)
2189                buf[0] = '1';
2190        else
2191                buf[0] = '0';
2192        buf[1] = '\n';
2193        buf[2] = 0x00;
2194        return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2195}
2196
2197static ssize_t write_enabled_file_bool(struct file *file,
2198               const char __user *user_buf, size_t count, loff_t *ppos)
2199{
2200        char buf[32];
2201        int buf_size;
2202
2203        buf_size = min(count, (sizeof(buf)-1));
2204        if (copy_from_user(buf, user_buf, buf_size))
2205                return -EFAULT;
2206
2207        switch (buf[0]) {
2208        case 'y':
2209        case 'Y':
2210        case '1':
2211                arm_all_kprobes();
2212                break;
2213        case 'n':
2214        case 'N':
2215        case '0':
2216                disarm_all_kprobes();
2217                break;
2218        }
2219
2220        return count;
2221}
2222
2223static const struct file_operations fops_kp = {
2224        .read =         read_enabled_file_bool,
2225        .write =        write_enabled_file_bool,
2226        .llseek =       default_llseek,
2227};
2228
2229static int __kprobes debugfs_kprobe_init(void)
2230{
2231        struct dentry *dir, *file;
2232        unsigned int value = 1;
2233
2234        dir = debugfs_create_dir("kprobes", NULL);
2235        if (!dir)
2236                return -ENOMEM;
2237
2238        file = debugfs_create_file("list", 0444, dir, NULL,
2239                                &debugfs_kprobes_operations);
2240        if (!file) {
2241                debugfs_remove(dir);
2242                return -ENOMEM;
2243        }
2244
2245        file = debugfs_create_file("enabled", 0600, dir,
2246                                        &value, &fops_kp);
2247        if (!file) {
2248                debugfs_remove(dir);
2249                return -ENOMEM;
2250        }
2251
2252        return 0;
2253}
2254
2255late_initcall(debugfs_kprobe_init);
2256#endif /* CONFIG_DEBUG_FS */
2257
2258module_init(init_kprobes);
2259
2260/* defined in arch/.../kernel/kprobes.c */
2261EXPORT_SYMBOL_GPL(jprobe_return);
2262
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