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/export.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        raw_spinlock_t lock ____cacheline_aligned_in_smp;
  82} kretprobe_table_locks[KPROBE_TABLE_SIZE];
  83
  84static raw_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 kprobe *p;
 338
 339        head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
 340        hlist_for_each_entry_rcu(p, head, hlist) {
 341                if (p->addr == addr)
 342                        return p;
 343        }
 344
 345        return NULL;
 346}
 347
 348static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
 349
 350/* Return true if the kprobe is an aggregator */
 351static inline int kprobe_aggrprobe(struct kprobe *p)
 352{
 353        return p->pre_handler == aggr_pre_handler;
 354}
 355
 356/* Return true(!0) if the kprobe is unused */
 357static inline int kprobe_unused(struct kprobe *p)
 358{
 359        return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
 360               list_empty(&p->list);
 361}
 362
 363/*
 364 * Keep all fields in the kprobe consistent
 365 */
 366static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
 367{
 368        memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
 369        memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
 370}
 371
 372#ifdef CONFIG_OPTPROBES
 373/* NOTE: change this value only with kprobe_mutex held */
 374static bool kprobes_allow_optimization;
 375
 376/*
 377 * Call all pre_handler on the list, but ignores its return value.
 378 * This must be called from arch-dep optimized caller.
 379 */
 380void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
 381{
 382        struct kprobe *kp;
 383
 384        list_for_each_entry_rcu(kp, &p->list, list) {
 385                if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 386                        set_kprobe_instance(kp);
 387                        kp->pre_handler(kp, regs);
 388                }
 389                reset_kprobe_instance();
 390        }
 391}
 392
 393/* Free optimized instructions and optimized_kprobe */
 394static __kprobes void free_aggr_kprobe(struct kprobe *p)
 395{
 396        struct optimized_kprobe *op;
 397
 398        op = container_of(p, struct optimized_kprobe, kp);
 399        arch_remove_optimized_kprobe(op);
 400        arch_remove_kprobe(p);
 401        kfree(op);
 402}
 403
 404/* Return true(!0) if the kprobe is ready for optimization. */
 405static inline int kprobe_optready(struct kprobe *p)
 406{
 407        struct optimized_kprobe *op;
 408
 409        if (kprobe_aggrprobe(p)) {
 410                op = container_of(p, struct optimized_kprobe, kp);
 411                return arch_prepared_optinsn(&op->optinsn);
 412        }
 413
 414        return 0;
 415}
 416
 417/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
 418static inline int kprobe_disarmed(struct kprobe *p)
 419{
 420        struct optimized_kprobe *op;
 421
 422        /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
 423        if (!kprobe_aggrprobe(p))
 424                return kprobe_disabled(p);
 425
 426        op = container_of(p, struct optimized_kprobe, kp);
 427
 428        return kprobe_disabled(p) && list_empty(&op->list);
 429}
 430
 431/* Return true(!0) if the probe is queued on (un)optimizing lists */
 432static int __kprobes kprobe_queued(struct kprobe *p)
 433{
 434        struct optimized_kprobe *op;
 435
 436        if (kprobe_aggrprobe(p)) {
 437                op = container_of(p, struct optimized_kprobe, kp);
 438                if (!list_empty(&op->list))
 439                        return 1;
 440        }
 441        return 0;
 442}
 443
 444/*
 445 * Return an optimized kprobe whose optimizing code replaces
 446 * instructions including addr (exclude breakpoint).
 447 */
 448static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
 449{
 450        int i;
 451        struct kprobe *p = NULL;
 452        struct optimized_kprobe *op;
 453
 454        /* Don't check i == 0, since that is a breakpoint case. */
 455        for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
 456                p = get_kprobe((void *)(addr - i));
 457
 458        if (p && kprobe_optready(p)) {
 459                op = container_of(p, struct optimized_kprobe, kp);
 460                if (arch_within_optimized_kprobe(op, addr))
 461                        return p;
 462        }
 463
 464        return NULL;
 465}
 466
 467/* Optimization staging list, protected by kprobe_mutex */
 468static LIST_HEAD(optimizing_list);
 469static LIST_HEAD(unoptimizing_list);
 470static LIST_HEAD(freeing_list);
 471
 472static void kprobe_optimizer(struct work_struct *work);
 473static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
 474#define OPTIMIZE_DELAY 5
 475
 476/*
 477 * Optimize (replace a breakpoint with a jump) kprobes listed on
 478 * optimizing_list.
 479 */
 480static __kprobes void do_optimize_kprobes(void)
 481{
 482        /* Optimization never be done when disarmed */
 483        if (kprobes_all_disarmed || !kprobes_allow_optimization ||
 484            list_empty(&optimizing_list))
 485                return;
 486
 487        /*
 488         * The optimization/unoptimization refers online_cpus via
 489         * stop_machine() and cpu-hotplug modifies online_cpus.
 490         * And same time, text_mutex will be held in cpu-hotplug and here.
 491         * This combination can cause a deadlock (cpu-hotplug try to lock
 492         * text_mutex but stop_machine can not be done because online_cpus
 493         * has been changed)
 494         * To avoid this deadlock, we need to call get_online_cpus()
 495         * for preventing cpu-hotplug outside of text_mutex locking.
 496         */
 497        get_online_cpus();
 498        mutex_lock(&text_mutex);
 499        arch_optimize_kprobes(&optimizing_list);
 500        mutex_unlock(&text_mutex);
 501        put_online_cpus();
 502}
 503
 504/*
 505 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
 506 * if need) kprobes listed on unoptimizing_list.
 507 */
 508static __kprobes void do_unoptimize_kprobes(void)
 509{
 510        struct optimized_kprobe *op, *tmp;
 511
 512        /* Unoptimization must be done anytime */
 513        if (list_empty(&unoptimizing_list))
 514                return;
 515
 516        /* Ditto to do_optimize_kprobes */
 517        get_online_cpus();
 518        mutex_lock(&text_mutex);
 519        arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
 520        /* Loop free_list for disarming */
 521        list_for_each_entry_safe(op, tmp, &freeing_list, list) {
 522                /* Disarm probes if marked disabled */
 523                if (kprobe_disabled(&op->kp))
 524                        arch_disarm_kprobe(&op->kp);
 525                if (kprobe_unused(&op->kp)) {
 526                        /*
 527                         * Remove unused probes from hash list. After waiting
 528                         * for synchronization, these probes are reclaimed.
 529                         * (reclaiming is done by do_free_cleaned_kprobes.)
 530                         */
 531                        hlist_del_rcu(&op->kp.hlist);
 532                } else
 533                        list_del_init(&op->list);
 534        }
 535        mutex_unlock(&text_mutex);
 536        put_online_cpus();
 537}
 538
 539/* Reclaim all kprobes on the free_list */
 540static __kprobes void do_free_cleaned_kprobes(void)
 541{
 542        struct optimized_kprobe *op, *tmp;
 543
 544        list_for_each_entry_safe(op, tmp, &freeing_list, list) {
 545                BUG_ON(!kprobe_unused(&op->kp));
 546                list_del_init(&op->list);
 547                free_aggr_kprobe(&op->kp);
 548        }
 549}
 550
 551/* Start optimizer after OPTIMIZE_DELAY passed */
 552static __kprobes void kick_kprobe_optimizer(void)
 553{
 554        schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
 555}
 556
 557/* Kprobe jump optimizer */
 558static __kprobes void kprobe_optimizer(struct work_struct *work)
 559{
 560        mutex_lock(&kprobe_mutex);
 561        /* Lock modules while optimizing kprobes */
 562        mutex_lock(&module_mutex);
 563
 564        /*
 565         * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
 566         * kprobes before waiting for quiesence period.
 567         */
 568        do_unoptimize_kprobes();
 569
 570        /*
 571         * Step 2: Wait for quiesence period to ensure all running interrupts
 572         * are done. Because optprobe may modify multiple instructions
 573         * there is a chance that Nth instruction is interrupted. In that
 574         * case, running interrupt can return to 2nd-Nth byte of jump
 575         * instruction. This wait is for avoiding it.
 576         */
 577        synchronize_sched();
 578
 579        /* Step 3: Optimize kprobes after quiesence period */
 580        do_optimize_kprobes();
 581
 582        /* Step 4: Free cleaned kprobes after quiesence period */
 583        do_free_cleaned_kprobes();
 584
 585        mutex_unlock(&module_mutex);
 586        mutex_unlock(&kprobe_mutex);
 587
 588        /* Step 5: Kick optimizer again if needed */
 589        if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
 590                kick_kprobe_optimizer();
 591}
 592
 593/* Wait for completing optimization and unoptimization */
 594static __kprobes void wait_for_kprobe_optimizer(void)
 595{
 596        mutex_lock(&kprobe_mutex);
 597
 598        while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
 599                mutex_unlock(&kprobe_mutex);
 600
 601                /* this will also make optimizing_work execute immmediately */
 602                flush_delayed_work(&optimizing_work);
 603                /* @optimizing_work might not have been queued yet, relax */
 604                cpu_relax();
 605
 606                mutex_lock(&kprobe_mutex);
 607        }
 608
 609        mutex_unlock(&kprobe_mutex);
 610}
 611
 612/* Optimize kprobe if p is ready to be optimized */
 613static __kprobes void optimize_kprobe(struct kprobe *p)
 614{
 615        struct optimized_kprobe *op;
 616
 617        /* Check if the kprobe is disabled or not ready for optimization. */
 618        if (!kprobe_optready(p) || !kprobes_allow_optimization ||
 619            (kprobe_disabled(p) || kprobes_all_disarmed))
 620                return;
 621
 622        /* Both of break_handler and post_handler are not supported. */
 623        if (p->break_handler || p->post_handler)
 624                return;
 625
 626        op = container_of(p, struct optimized_kprobe, kp);
 627
 628        /* Check there is no other kprobes at the optimized instructions */
 629        if (arch_check_optimized_kprobe(op) < 0)
 630                return;
 631
 632        /* Check if it is already optimized. */
 633        if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
 634                return;
 635        op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
 636
 637        if (!list_empty(&op->list))
 638                /* This is under unoptimizing. Just dequeue the probe */
 639                list_del_init(&op->list);
 640        else {
 641                list_add(&op->list, &optimizing_list);
 642                kick_kprobe_optimizer();
 643        }
 644}
 645
 646/* Short cut to direct unoptimizing */
 647static __kprobes void force_unoptimize_kprobe(struct optimized_kprobe *op)
 648{
 649        get_online_cpus();
 650        arch_unoptimize_kprobe(op);
 651        put_online_cpus();
 652        if (kprobe_disabled(&op->kp))
 653                arch_disarm_kprobe(&op->kp);
 654}
 655
 656/* Unoptimize a kprobe if p is optimized */
 657static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force)
 658{
 659        struct optimized_kprobe *op;
 660
 661        if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
 662                return; /* This is not an optprobe nor optimized */
 663
 664        op = container_of(p, struct optimized_kprobe, kp);
 665        if (!kprobe_optimized(p)) {
 666                /* Unoptimized or unoptimizing case */
 667                if (force && !list_empty(&op->list)) {
 668                        /*
 669                         * Only if this is unoptimizing kprobe and forced,
 670                         * forcibly unoptimize it. (No need to unoptimize
 671                         * unoptimized kprobe again :)
 672                         */
 673                        list_del_init(&op->list);
 674                        force_unoptimize_kprobe(op);
 675                }
 676                return;
 677        }
 678
 679        op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 680        if (!list_empty(&op->list)) {
 681                /* Dequeue from the optimization queue */
 682                list_del_init(&op->list);
 683                return;
 684        }
 685        /* Optimized kprobe case */
 686        if (force)
 687                /* Forcibly update the code: this is a special case */
 688                force_unoptimize_kprobe(op);
 689        else {
 690                list_add(&op->list, &unoptimizing_list);
 691                kick_kprobe_optimizer();
 692        }
 693}
 694
 695/* Cancel unoptimizing for reusing */
 696static void reuse_unused_kprobe(struct kprobe *ap)
 697{
 698        struct optimized_kprobe *op;
 699
 700        BUG_ON(!kprobe_unused(ap));
 701        /*
 702         * Unused kprobe MUST be on the way of delayed unoptimizing (means
 703         * there is still a relative jump) and disabled.
 704         */
 705        op = container_of(ap, struct optimized_kprobe, kp);
 706        if (unlikely(list_empty(&op->list)))
 707                printk(KERN_WARNING "Warning: found a stray unused "
 708                        "aggrprobe@%p\n", ap->addr);
 709        /* Enable the probe again */
 710        ap->flags &= ~KPROBE_FLAG_DISABLED;
 711        /* Optimize it again (remove from op->list) */
 712        BUG_ON(!kprobe_optready(ap));
 713        optimize_kprobe(ap);
 714}
 715
 716/* Remove optimized instructions */
 717static void __kprobes kill_optimized_kprobe(struct kprobe *p)
 718{
 719        struct optimized_kprobe *op;
 720
 721        op = container_of(p, struct optimized_kprobe, kp);
 722        if (!list_empty(&op->list))
 723                /* Dequeue from the (un)optimization queue */
 724                list_del_init(&op->list);
 725        op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 726
 727        if (kprobe_unused(p)) {
 728                /* Enqueue if it is unused */
 729                list_add(&op->list, &freeing_list);
 730                /*
 731                 * Remove unused probes from the hash list. After waiting
 732                 * for synchronization, this probe is reclaimed.
 733                 * (reclaiming is done by do_free_cleaned_kprobes().)
 734                 */
 735                hlist_del_rcu(&op->kp.hlist);
 736        }
 737
 738        /* Don't touch the code, because it is already freed. */
 739        arch_remove_optimized_kprobe(op);
 740}
 741
 742/* Try to prepare optimized instructions */
 743static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
 744{
 745        struct optimized_kprobe *op;
 746
 747        op = container_of(p, struct optimized_kprobe, kp);
 748        arch_prepare_optimized_kprobe(op);
 749}
 750
 751/* Allocate new optimized_kprobe and try to prepare optimized instructions */
 752static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 753{
 754        struct optimized_kprobe *op;
 755
 756        op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
 757        if (!op)
 758                return NULL;
 759
 760        INIT_LIST_HEAD(&op->list);
 761        op->kp.addr = p->addr;
 762        arch_prepare_optimized_kprobe(op);
 763
 764        return &op->kp;
 765}
 766
 767static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
 768
 769/*
 770 * Prepare an optimized_kprobe and optimize it
 771 * NOTE: p must be a normal registered kprobe
 772 */
 773static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
 774{
 775        struct kprobe *ap;
 776        struct optimized_kprobe *op;
 777
 778        /* Impossible to optimize ftrace-based kprobe */
 779        if (kprobe_ftrace(p))
 780                return;
 781
 782        /* For preparing optimization, jump_label_text_reserved() is called */
 783        jump_label_lock();
 784        mutex_lock(&text_mutex);
 785
 786        ap = alloc_aggr_kprobe(p);
 787        if (!ap)
 788                goto out;
 789
 790        op = container_of(ap, struct optimized_kprobe, kp);
 791        if (!arch_prepared_optinsn(&op->optinsn)) {
 792                /* If failed to setup optimizing, fallback to kprobe */
 793                arch_remove_optimized_kprobe(op);
 794                kfree(op);
 795                goto out;
 796        }
 797
 798        init_aggr_kprobe(ap, p);
 799        optimize_kprobe(ap);    /* This just kicks optimizer thread */
 800
 801out:
 802        mutex_unlock(&text_mutex);
 803        jump_label_unlock();
 804}
 805
 806#ifdef CONFIG_SYSCTL
 807static void __kprobes optimize_all_kprobes(void)
 808{
 809        struct hlist_head *head;
 810        struct kprobe *p;
 811        unsigned int i;
 812
 813        mutex_lock(&kprobe_mutex);
 814        /* If optimization is already allowed, just return */
 815        if (kprobes_allow_optimization)
 816                goto out;
 817
 818        kprobes_allow_optimization = true;
 819        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 820                head = &kprobe_table[i];
 821                hlist_for_each_entry_rcu(p, head, hlist)
 822                        if (!kprobe_disabled(p))
 823                                optimize_kprobe(p);
 824        }
 825        printk(KERN_INFO "Kprobes globally optimized\n");
 826out:
 827        mutex_unlock(&kprobe_mutex);
 828}
 829
 830static void __kprobes unoptimize_all_kprobes(void)
 831{
 832        struct hlist_head *head;
 833        struct kprobe *p;
 834        unsigned int i;
 835
 836        mutex_lock(&kprobe_mutex);
 837        /* If optimization is already prohibited, just return */
 838        if (!kprobes_allow_optimization) {
 839                mutex_unlock(&kprobe_mutex);
 840                return;
 841        }
 842
 843        kprobes_allow_optimization = false;
 844        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 845                head = &kprobe_table[i];
 846                hlist_for_each_entry_rcu(p, head, hlist) {
 847                        if (!kprobe_disabled(p))
 848                                unoptimize_kprobe(p, false);
 849                }
 850        }
 851        mutex_unlock(&kprobe_mutex);
 852
 853        /* Wait for unoptimizing completion */
 854        wait_for_kprobe_optimizer();
 855        printk(KERN_INFO "Kprobes globally unoptimized\n");
 856}
 857
 858static DEFINE_MUTEX(kprobe_sysctl_mutex);
 859int sysctl_kprobes_optimization;
 860int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
 861                                      void __user *buffer, size_t *length,
 862                                      loff_t *ppos)
 863{
 864        int ret;
 865
 866        mutex_lock(&kprobe_sysctl_mutex);
 867        sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
 868        ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
 869
 870        if (sysctl_kprobes_optimization)
 871                optimize_all_kprobes();
 872        else
 873                unoptimize_all_kprobes();
 874        mutex_unlock(&kprobe_sysctl_mutex);
 875
 876        return ret;
 877}
 878#endif /* CONFIG_SYSCTL */
 879
 880/* Put a breakpoint for a probe. Must be called with text_mutex locked */
 881static void __kprobes __arm_kprobe(struct kprobe *p)
 882{
 883        struct kprobe *_p;
 884
 885        /* Check collision with other optimized kprobes */
 886        _p = get_optimized_kprobe((unsigned long)p->addr);
 887        if (unlikely(_p))
 888                /* Fallback to unoptimized kprobe */
 889                unoptimize_kprobe(_p, true);
 890
 891        arch_arm_kprobe(p);
 892        optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
 893}
 894
 895/* Remove the breakpoint of a probe. Must be called with text_mutex locked */
 896static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt)
 897{
 898        struct kprobe *_p;
 899
 900        unoptimize_kprobe(p, false);    /* Try to unoptimize */
 901
 902        if (!kprobe_queued(p)) {
 903                arch_disarm_kprobe(p);
 904                /* If another kprobe was blocked, optimize it. */
 905                _p = get_optimized_kprobe((unsigned long)p->addr);
 906                if (unlikely(_p) && reopt)
 907                        optimize_kprobe(_p);
 908        }
 909        /* TODO: reoptimize others after unoptimized this probe */
 910}
 911
 912#else /* !CONFIG_OPTPROBES */
 913
 914#define optimize_kprobe(p)                      do {} while (0)
 915#define unoptimize_kprobe(p, f)                 do {} while (0)
 916#define kill_optimized_kprobe(p)                do {} while (0)
 917#define prepare_optimized_kprobe(p)             do {} while (0)
 918#define try_to_optimize_kprobe(p)               do {} while (0)
 919#define __arm_kprobe(p)                         arch_arm_kprobe(p)
 920#define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
 921#define kprobe_disarmed(p)                      kprobe_disabled(p)
 922#define wait_for_kprobe_optimizer()             do {} while (0)
 923
 924/* There should be no unused kprobes can be reused without optimization */
 925static void reuse_unused_kprobe(struct kprobe *ap)
 926{
 927        printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
 928        BUG_ON(kprobe_unused(ap));
 929}
 930
 931static __kprobes void free_aggr_kprobe(struct kprobe *p)
 932{
 933        arch_remove_kprobe(p);
 934        kfree(p);
 935}
 936
 937static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 938{
 939        return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
 940}
 941#endif /* CONFIG_OPTPROBES */
 942
 943#ifdef CONFIG_KPROBES_ON_FTRACE
 944static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
 945        .func = kprobe_ftrace_handler,
 946        .flags = FTRACE_OPS_FL_SAVE_REGS,
 947};
 948static int kprobe_ftrace_enabled;
 949
 950/* Must ensure p->addr is really on ftrace */
 951static int __kprobes prepare_kprobe(struct kprobe *p)
 952{
 953        if (!kprobe_ftrace(p))
 954                return arch_prepare_kprobe(p);
 955
 956        return arch_prepare_kprobe_ftrace(p);
 957}
 958
 959/* Caller must lock kprobe_mutex */
 960static void __kprobes arm_kprobe_ftrace(struct kprobe *p)
 961{
 962        int ret;
 963
 964        ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 965                                   (unsigned long)p->addr, 0, 0);
 966        WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 967        kprobe_ftrace_enabled++;
 968        if (kprobe_ftrace_enabled == 1) {
 969                ret = register_ftrace_function(&kprobe_ftrace_ops);
 970                WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 971        }
 972}
 973
 974/* Caller must lock kprobe_mutex */
 975static void __kprobes disarm_kprobe_ftrace(struct kprobe *p)
 976{
 977        int ret;
 978
 979        kprobe_ftrace_enabled--;
 980        if (kprobe_ftrace_enabled == 0) {
 981                ret = unregister_ftrace_function(&kprobe_ftrace_ops);
 982                WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 983        }
 984        ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 985                           (unsigned long)p->addr, 1, 0);
 986        WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 987}
 988#else   /* !CONFIG_KPROBES_ON_FTRACE */
 989#define prepare_kprobe(p)       arch_prepare_kprobe(p)
 990#define arm_kprobe_ftrace(p)    do {} while (0)
 991#define disarm_kprobe_ftrace(p) do {} while (0)
 992#endif
 993
 994/* Arm a kprobe with text_mutex */
 995static void __kprobes arm_kprobe(struct kprobe *kp)
 996{
 997        if (unlikely(kprobe_ftrace(kp))) {
 998                arm_kprobe_ftrace(kp);
 999                return;
1000        }
1001        /*
1002         * Here, since __arm_kprobe() doesn't use stop_machine(),
1003         * this doesn't cause deadlock on text_mutex. So, we don't
1004         * need get_online_cpus().
1005         */
1006        mutex_lock(&text_mutex);
1007        __arm_kprobe(kp);
1008        mutex_unlock(&text_mutex);
1009}
1010
1011/* Disarm a kprobe with text_mutex */
1012static void __kprobes disarm_kprobe(struct kprobe *kp, bool reopt)
1013{
1014        if (unlikely(kprobe_ftrace(kp))) {
1015                disarm_kprobe_ftrace(kp);
1016                return;
1017        }
1018        /* Ditto */
1019        mutex_lock(&text_mutex);
1020        __disarm_kprobe(kp, reopt);
1021        mutex_unlock(&text_mutex);
1022}
1023
1024/*
1025 * Aggregate handlers for multiple kprobes support - these handlers
1026 * take care of invoking the individual kprobe handlers on p->list
1027 */
1028static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1029{
1030        struct kprobe *kp;
1031
1032        list_for_each_entry_rcu(kp, &p->list, list) {
1033                if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1034                        set_kprobe_instance(kp);
1035                        if (kp->pre_handler(kp, regs))
1036                                return 1;
1037                }
1038                reset_kprobe_instance();
1039        }
1040        return 0;
1041}
1042
1043static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1044                                        unsigned long flags)
1045{
1046        struct kprobe *kp;
1047
1048        list_for_each_entry_rcu(kp, &p->list, list) {
1049                if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1050                        set_kprobe_instance(kp);
1051                        kp->post_handler(kp, regs, flags);
1052                        reset_kprobe_instance();
1053                }
1054        }
1055}
1056
1057static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1058                                        int trapnr)
1059{
1060        struct kprobe *cur = __this_cpu_read(kprobe_instance);
1061
1062        /*
1063         * if we faulted "during" the execution of a user specified
1064         * probe handler, invoke just that probe's fault handler
1065         */
1066        if (cur && cur->fault_handler) {
1067                if (cur->fault_handler(cur, regs, trapnr))
1068                        return 1;
1069        }
1070        return 0;
1071}
1072
1073static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
1074{
1075        struct kprobe *cur = __this_cpu_read(kprobe_instance);
1076        int ret = 0;
1077
1078        if (cur && cur->break_handler) {
1079                if (cur->break_handler(cur, regs))
1080                        ret = 1;
1081        }
1082        reset_kprobe_instance();
1083        return ret;
1084}
1085
1086/* Walks the list and increments nmissed count for multiprobe case */
1087void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
1088{
1089        struct kprobe *kp;
1090        if (!kprobe_aggrprobe(p)) {
1091                p->nmissed++;
1092        } else {
1093                list_for_each_entry_rcu(kp, &p->list, list)
1094                        kp->nmissed++;
1095        }
1096        return;
1097}
1098
1099void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
1100                                struct hlist_head *head)
1101{
1102        struct kretprobe *rp = ri->rp;
1103
1104        /* remove rp inst off the rprobe_inst_table */
1105        hlist_del(&ri->hlist);
1106        INIT_HLIST_NODE(&ri->hlist);
1107        if (likely(rp)) {
1108                raw_spin_lock(&rp->lock);
1109                hlist_add_head(&ri->hlist, &rp->free_instances);
1110                raw_spin_unlock(&rp->lock);
1111        } else
1112                /* Unregistering */
1113                hlist_add_head(&ri->hlist, head);
1114}
1115
1116void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
1117                         struct hlist_head **head, unsigned long *flags)
1118__acquires(hlist_lock)
1119{
1120        unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1121        raw_spinlock_t *hlist_lock;
1122
1123        *head = &kretprobe_inst_table[hash];
1124        hlist_lock = kretprobe_table_lock_ptr(hash);
1125        raw_spin_lock_irqsave(hlist_lock, *flags);
1126}
1127
1128static void __kprobes kretprobe_table_lock(unsigned long hash,
1129        unsigned long *flags)
1130__acquires(hlist_lock)
1131{
1132        raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1133        raw_spin_lock_irqsave(hlist_lock, *flags);
1134}
1135
1136void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
1137        unsigned long *flags)
1138__releases(hlist_lock)
1139{
1140        unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1141        raw_spinlock_t *hlist_lock;
1142
1143        hlist_lock = kretprobe_table_lock_ptr(hash);
1144        raw_spin_unlock_irqrestore(hlist_lock, *flags);
1145}
1146
1147static void __kprobes kretprobe_table_unlock(unsigned long hash,
1148       unsigned long *flags)
1149__releases(hlist_lock)
1150{
1151        raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1152        raw_spin_unlock_irqrestore(hlist_lock, *flags);
1153}
1154
1155/*
1156 * This function is called from finish_task_switch when task tk becomes dead,
1157 * so that we can recycle any function-return probe instances associated
1158 * with this task. These left over instances represent probed functions
1159 * that have been called but will never return.
1160 */
1161void __kprobes kprobe_flush_task(struct task_struct *tk)
1162{
1163        struct kretprobe_instance *ri;
1164        struct hlist_head *head, empty_rp;
1165        struct hlist_node *tmp;
1166        unsigned long hash, flags = 0;
1167
1168        if (unlikely(!kprobes_initialized))
1169                /* Early boot.  kretprobe_table_locks not yet initialized. */
1170                return;
1171
1172        INIT_HLIST_HEAD(&empty_rp);
1173        hash = hash_ptr(tk, KPROBE_HASH_BITS);
1174        head = &kretprobe_inst_table[hash];
1175        kretprobe_table_lock(hash, &flags);
1176        hlist_for_each_entry_safe(ri, tmp, head, hlist) {
1177                if (ri->task == tk)
1178                        recycle_rp_inst(ri, &empty_rp);
1179        }
1180        kretprobe_table_unlock(hash, &flags);
1181        hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
1182                hlist_del(&ri->hlist);
1183                kfree(ri);
1184        }
1185}
1186
1187static inline void free_rp_inst(struct kretprobe *rp)
1188{
1189        struct kretprobe_instance *ri;
1190        struct hlist_node *next;
1191
1192        hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1193                hlist_del(&ri->hlist);
1194                kfree(ri);
1195        }
1196}
1197
1198static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
1199{
1200        unsigned long flags, hash;
1201        struct kretprobe_instance *ri;
1202        struct hlist_node *next;
1203        struct hlist_head *head;
1204
1205        /* No race here */
1206        for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1207                kretprobe_table_lock(hash, &flags);
1208                head = &kretprobe_inst_table[hash];
1209                hlist_for_each_entry_safe(ri, next, head, hlist) {
1210                        if (ri->rp == rp)
1211                                ri->rp = NULL;
1212                }
1213                kretprobe_table_unlock(hash, &flags);
1214        }
1215        free_rp_inst(rp);
1216}
1217
1218/*
1219* Add the new probe to ap->list. Fail if this is the
1220* second jprobe at the address - two jprobes can't coexist
1221*/
1222static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1223{
1224        BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1225
1226        if (p->break_handler || p->post_handler)
1227                unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1228
1229        if (p->break_handler) {
1230                if (ap->break_handler)
1231                        return -EEXIST;
1232                list_add_tail_rcu(&p->list, &ap->list);
1233                ap->break_handler = aggr_break_handler;
1234        } else
1235                list_add_rcu(&p->list, &ap->list);
1236        if (p->post_handler && !ap->post_handler)
1237                ap->post_handler = aggr_post_handler;
1238
1239        return 0;
1240}
1241
1242/*
1243 * Fill in the required fields of the "manager kprobe". Replace the
1244 * earlier kprobe in the hlist with the manager kprobe
1245 */
1246static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1247{
1248        /* Copy p's insn slot to ap */
1249        copy_kprobe(p, ap);
1250        flush_insn_slot(ap);
1251        ap->addr = p->addr;
1252        ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1253        ap->pre_handler = aggr_pre_handler;
1254        ap->fault_handler = aggr_fault_handler;
1255        /* We don't care the kprobe which has gone. */
1256        if (p->post_handler && !kprobe_gone(p))
1257                ap->post_handler = aggr_post_handler;
1258        if (p->break_handler && !kprobe_gone(p))
1259                ap->break_handler = aggr_break_handler;
1260
1261        INIT_LIST_HEAD(&ap->list);
1262        INIT_HLIST_NODE(&ap->hlist);
1263
1264        list_add_rcu(&p->list, &ap->list);
1265        hlist_replace_rcu(&p->hlist, &ap->hlist);
1266}
1267
1268/*
1269 * This is the second or subsequent kprobe at the address - handle
1270 * the intricacies
1271 */
1272static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
1273                                          struct kprobe *p)
1274{
1275        int ret = 0;
1276        struct kprobe *ap = orig_p;
1277
1278        /* For preparing optimization, jump_label_text_reserved() is called */
1279        jump_label_lock();
1280        /*
1281         * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1282         * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1283         */
1284        get_online_cpus();
1285        mutex_lock(&text_mutex);
1286
1287        if (!kprobe_aggrprobe(orig_p)) {
1288                /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1289                ap = alloc_aggr_kprobe(orig_p);
1290                if (!ap) {
1291                        ret = -ENOMEM;
1292                        goto out;
1293                }
1294                init_aggr_kprobe(ap, orig_p);
1295        } else if (kprobe_unused(ap))
1296                /* This probe is going to die. Rescue it */
1297                reuse_unused_kprobe(ap);
1298
1299        if (kprobe_gone(ap)) {
1300                /*
1301                 * Attempting to insert new probe at the same location that
1302                 * had a probe in the module vaddr area which already
1303                 * freed. So, the instruction slot has already been
1304                 * released. We need a new slot for the new probe.
1305                 */
1306                ret = arch_prepare_kprobe(ap);
1307                if (ret)
1308                        /*
1309                         * Even if fail to allocate new slot, don't need to
1310                         * free aggr_probe. It will be used next time, or
1311                         * freed by unregister_kprobe.
1312                         */
1313                        goto out;
1314
1315                /* Prepare optimized instructions if possible. */
1316                prepare_optimized_kprobe(ap);
1317
1318                /*
1319                 * Clear gone flag to prevent allocating new slot again, and
1320                 * set disabled flag because it is not armed yet.
1321                 */
1322                ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1323                            | KPROBE_FLAG_DISABLED;
1324        }
1325
1326        /* Copy ap's insn slot to p */
1327        copy_kprobe(ap, p);
1328        ret = add_new_kprobe(ap, p);
1329
1330out:
1331        mutex_unlock(&text_mutex);
1332        put_online_cpus();
1333        jump_label_unlock();
1334
1335        if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1336                ap->flags &= ~KPROBE_FLAG_DISABLED;
1337                if (!kprobes_all_disarmed)
1338                        /* Arm the breakpoint again. */
1339                        arm_kprobe(ap);
1340        }
1341        return ret;
1342}
1343
1344static int __kprobes in_kprobes_functions(unsigned long addr)
1345{
1346        struct kprobe_blackpoint *kb;
1347
1348        if (addr >= (unsigned long)__kprobes_text_start &&
1349            addr < (unsigned long)__kprobes_text_end)
1350                return -EINVAL;
1351        /*
1352         * If there exists a kprobe_blacklist, verify and
1353         * fail any probe registration in the prohibited area
1354         */
1355        for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1356                if (kb->start_addr) {
1357                        if (addr >= kb->start_addr &&
1358                            addr < (kb->start_addr + kb->range))
1359                                return -EINVAL;
1360                }
1361        }
1362        return 0;
1363}
1364
1365/*
1366 * If we have a symbol_name argument, look it up and add the offset field
1367 * to it. This way, we can specify a relative address to a symbol.
1368 * This returns encoded errors if it fails to look up symbol or invalid
1369 * combination of parameters.
1370 */
1371static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
1372{
1373        kprobe_opcode_t *addr = p->addr;
1374
1375        if ((p->symbol_name && p->addr) ||
1376            (!p->symbol_name && !p->addr))
1377                goto invalid;
1378
1379        if (p->symbol_name) {
1380                kprobe_lookup_name(p->symbol_name, addr);
1381                if (!addr)
1382                        return ERR_PTR(-ENOENT);
1383        }
1384
1385        addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1386        if (addr)
1387                return addr;
1388
1389invalid:
1390        return ERR_PTR(-EINVAL);
1391}
1392
1393/* Check passed kprobe is valid and return kprobe in kprobe_table. */
1394static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
1395{
1396        struct kprobe *ap, *list_p;
1397
1398        ap = get_kprobe(p->addr);
1399        if (unlikely(!ap))
1400                return NULL;
1401
1402        if (p != ap) {
1403                list_for_each_entry_rcu(list_p, &ap->list, list)
1404                        if (list_p == p)
1405                        /* kprobe p is a valid probe */
1406                                goto valid;
1407                return NULL;
1408        }
1409valid:
1410        return ap;
1411}
1412
1413/* Return error if the kprobe is being re-registered */
1414static inline int check_kprobe_rereg(struct kprobe *p)
1415{
1416        int ret = 0;
1417
1418        mutex_lock(&kprobe_mutex);
1419        if (__get_valid_kprobe(p))
1420                ret = -EINVAL;
1421        mutex_unlock(&kprobe_mutex);
1422
1423        return ret;
1424}
1425
1426static __kprobes int check_kprobe_address_safe(struct kprobe *p,
1427                                               struct module **probed_mod)
1428{
1429        int ret = 0;
1430        unsigned long ftrace_addr;
1431
1432        /*
1433         * If the address is located on a ftrace nop, set the
1434         * breakpoint to the following instruction.
1435         */
1436        ftrace_addr = ftrace_location((unsigned long)p->addr);
1437        if (ftrace_addr) {
1438#ifdef CONFIG_KPROBES_ON_FTRACE
1439                /* Given address is not on the instruction boundary */
1440                if ((unsigned long)p->addr != ftrace_addr)
1441                        return -EILSEQ;
1442                p->flags |= KPROBE_FLAG_FTRACE;
1443#else   /* !CONFIG_KPROBES_ON_FTRACE */
1444                return -EINVAL;
1445#endif
1446        }
1447
1448        jump_label_lock();
1449        preempt_disable();
1450
1451        /* Ensure it is not in reserved area nor out of text */
1452        if (!kernel_text_address((unsigned long) p->addr) ||
1453            in_kprobes_functions((unsigned long) p->addr) ||
1454            jump_label_text_reserved(p->addr, p->addr)) {
1455                ret = -EINVAL;
1456                goto out;
1457        }
1458
1459        /* Check if are we probing a module */
1460        *probed_mod = __module_text_address((unsigned long) p->addr);
1461        if (*probed_mod) {
1462                /*
1463                 * We must hold a refcount of the probed module while updating
1464                 * its code to prohibit unexpected unloading.
1465                 */
1466                if (unlikely(!try_module_get(*probed_mod))) {
1467                        ret = -ENOENT;
1468                        goto out;
1469                }
1470
1471                /*
1472                 * If the module freed .init.text, we couldn't insert
1473                 * kprobes in there.
1474                 */
1475                if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1476                    (*probed_mod)->state != MODULE_STATE_COMING) {
1477                        module_put(*probed_mod);
1478                        *probed_mod = NULL;
1479                        ret = -ENOENT;
1480                }
1481        }
1482out:
1483        preempt_enable();
1484        jump_label_unlock();
1485
1486        return ret;
1487}
1488
1489int __kprobes register_kprobe(struct kprobe *p)
1490{
1491        int ret;
1492        struct kprobe *old_p;
1493        struct module *probed_mod;
1494        kprobe_opcode_t *addr;
1495
1496        /* Adjust probe address from symbol */
1497        addr = kprobe_addr(p);
1498        if (IS_ERR(addr))
1499                return PTR_ERR(addr);
1500        p->addr = addr;
1501
1502        ret = check_kprobe_rereg(p);
1503        if (ret)
1504                return ret;
1505
1506        /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1507        p->flags &= KPROBE_FLAG_DISABLED;
1508        p->nmissed = 0;
1509        INIT_LIST_HEAD(&p->list);
1510
1511        ret = check_kprobe_address_safe(p, &probed_mod);
1512        if (ret)
1513                return ret;
1514
1515        mutex_lock(&kprobe_mutex);
1516
1517        old_p = get_kprobe(p->addr);
1518        if (old_p) {
1519                /* Since this may unoptimize old_p, locking text_mutex. */
1520                ret = register_aggr_kprobe(old_p, p);
1521                goto out;
1522        }
1523
1524        mutex_lock(&text_mutex);        /* Avoiding text modification */
1525        ret = prepare_kprobe(p);
1526        mutex_unlock(&text_mutex);
1527        if (ret)
1528                goto out;
1529
1530        INIT_HLIST_NODE(&p->hlist);
1531        hlist_add_head_rcu(&p->hlist,
1532                       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1533
1534        if (!kprobes_all_disarmed && !kprobe_disabled(p))
1535                arm_kprobe(p);
1536
1537        /* Try to optimize kprobe */
1538        try_to_optimize_kprobe(p);
1539
1540out:
1541        mutex_unlock(&kprobe_mutex);
1542
1543        if (probed_mod)
1544                module_put(probed_mod);
1545
1546        return ret;
1547}
1548EXPORT_SYMBOL_GPL(register_kprobe);
1549
1550/* Check if all probes on the aggrprobe are disabled */
1551static int __kprobes aggr_kprobe_disabled(struct kprobe *ap)
1552{
1553        struct kprobe *kp;
1554
1555        list_for_each_entry_rcu(kp, &ap->list, list)
1556                if (!kprobe_disabled(kp))
1557                        /*
1558                         * There is an active probe on the list.
1559                         * We can't disable this ap.
1560                         */
1561                        return 0;
1562
1563        return 1;
1564}
1565
1566/* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1567static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
1568{
1569        struct kprobe *orig_p;
1570
1571        /* Get an original kprobe for return */
1572        orig_p = __get_valid_kprobe(p);
1573        if (unlikely(orig_p == NULL))
1574                return NULL;
1575
1576        if (!kprobe_disabled(p)) {
1577                /* Disable probe if it is a child probe */
1578                if (p != orig_p)
1579                        p->flags |= KPROBE_FLAG_DISABLED;
1580
1581                /* Try to disarm and disable this/parent probe */
1582                if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1583                        disarm_kprobe(orig_p, true);
1584                        orig_p->flags |= KPROBE_FLAG_DISABLED;
1585                }
1586        }
1587
1588        return orig_p;
1589}
1590
1591/*
1592 * Unregister a kprobe without a scheduler synchronization.
1593 */
1594static int __kprobes __unregister_kprobe_top(struct kprobe *p)
1595{
1596        struct kprobe *ap, *list_p;
1597
1598        /* Disable kprobe. This will disarm it if needed. */
1599        ap = __disable_kprobe(p);
1600        if (ap == NULL)
1601                return -EINVAL;
1602
1603        if (ap == p)
1604                /*
1605                 * This probe is an independent(and non-optimized) kprobe
1606                 * (not an aggrprobe). Remove from the hash list.
1607                 */
1608                goto disarmed;
1609
1610        /* Following process expects this probe is an aggrprobe */
1611        WARN_ON(!kprobe_aggrprobe(ap));
1612
1613        if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1614                /*
1615                 * !disarmed could be happen if the probe is under delayed
1616                 * unoptimizing.
1617                 */
1618                goto disarmed;
1619        else {
1620                /* If disabling probe has special handlers, update aggrprobe */
1621                if (p->break_handler && !kprobe_gone(p))
1622                        ap->break_handler = NULL;
1623                if (p->post_handler && !kprobe_gone(p)) {
1624                        list_for_each_entry_rcu(list_p, &ap->list, list) {
1625                                if ((list_p != p) && (list_p->post_handler))
1626                                        goto noclean;
1627                        }
1628                        ap->post_handler = NULL;
1629                }
1630noclean:
1631                /*
1632                 * Remove from the aggrprobe: this path will do nothing in
1633                 * __unregister_kprobe_bottom().
1634                 */
1635                list_del_rcu(&p->list);
1636                if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1637                        /*
1638                         * Try to optimize this probe again, because post
1639                         * handler may have been changed.
1640                         */
1641                        optimize_kprobe(ap);
1642        }
1643        return 0;
1644
1645disarmed:
1646        BUG_ON(!kprobe_disarmed(ap));
1647        hlist_del_rcu(&ap->hlist);
1648        return 0;
1649}
1650
1651static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
1652{
1653        struct kprobe *ap;
1654
1655        if (list_empty(&p->list))
1656                /* This is an independent kprobe */
1657                arch_remove_kprobe(p);
1658        else if (list_is_singular(&p->list)) {
1659                /* This is the last child of an aggrprobe */
1660                ap = list_entry(p->list.next, struct kprobe, list);
1661                list_del(&p->list);
1662                free_aggr_kprobe(ap);
1663        }
1664        /* Otherwise, do nothing. */
1665}
1666
1667int __kprobes register_kprobes(struct kprobe **kps, int num)
1668{
1669        int i, ret = 0;
1670
1671        if (num <= 0)
1672                return -EINVAL;
1673        for (i = 0; i < num; i++) {
1674                ret = register_kprobe(kps[i]);
1675                if (ret < 0) {
1676                        if (i > 0)
1677                                unregister_kprobes(kps, i);
1678                        break;
1679                }
1680        }
1681        return ret;
1682}
1683EXPORT_SYMBOL_GPL(register_kprobes);
1684
1685void __kprobes unregister_kprobe(struct kprobe *p)
1686{
1687        unregister_kprobes(&p, 1);
1688}
1689EXPORT_SYMBOL_GPL(unregister_kprobe);
1690
1691void __kprobes unregister_kprobes(struct kprobe **kps, int num)
1692{
1693        int i;
1694
1695        if (num <= 0)
1696                return;
1697        mutex_lock(&kprobe_mutex);
1698        for (i = 0; i < num; i++)
1699                if (__unregister_kprobe_top(kps[i]) < 0)
1700                        kps[i]->addr = NULL;
1701        mutex_unlock(&kprobe_mutex);
1702
1703        synchronize_sched();
1704        for (i = 0; i < num; i++)
1705                if (kps[i]->addr)
1706                        __unregister_kprobe_bottom(kps[i]);
1707}
1708EXPORT_SYMBOL_GPL(unregister_kprobes);
1709
1710static struct notifier_block kprobe_exceptions_nb = {
1711        .notifier_call = kprobe_exceptions_notify,
1712        .priority = 0x7fffffff /* we need to be notified first */
1713};
1714
1715unsigned long __weak arch_deref_entry_point(void *entry)
1716{
1717        return (unsigned long)entry;
1718}
1719
1720int __kprobes register_jprobes(struct jprobe **jps, int num)
1721{
1722        struct jprobe *jp;
1723        int ret = 0, i;
1724
1725        if (num <= 0)
1726                return -EINVAL;
1727        for (i = 0; i < num; i++) {
1728                unsigned long addr, offset;
1729                jp = jps[i];
1730                addr = arch_deref_entry_point(jp->entry);
1731
1732                /* Verify probepoint is a function entry point */
1733                if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1734                    offset == 0) {
1735                        jp->kp.pre_handler = setjmp_pre_handler;
1736                        jp->kp.break_handler = longjmp_break_handler;
1737                        ret = register_kprobe(&jp->kp);
1738                } else
1739                        ret = -EINVAL;
1740
1741                if (ret < 0) {
1742                        if (i > 0)
1743                                unregister_jprobes(jps, i);
1744                        break;
1745                }
1746        }
1747        return ret;
1748}
1749EXPORT_SYMBOL_GPL(register_jprobes);
1750
1751int __kprobes register_jprobe(struct jprobe *jp)
1752{
1753        return register_jprobes(&jp, 1);
1754}
1755EXPORT_SYMBOL_GPL(register_jprobe);
1756
1757void __kprobes unregister_jprobe(struct jprobe *jp)
1758{
1759        unregister_jprobes(&jp, 1);
1760}
1761EXPORT_SYMBOL_GPL(unregister_jprobe);
1762
1763void __kprobes unregister_jprobes(struct jprobe **jps, int num)
1764{
1765        int i;
1766
1767        if (num <= 0)
1768                return;
1769        mutex_lock(&kprobe_mutex);
1770        for (i = 0; i < num; i++)
1771                if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1772                        jps[i]->kp.addr = NULL;
1773        mutex_unlock(&kprobe_mutex);
1774
1775        synchronize_sched();
1776        for (i = 0; i < num; i++) {
1777                if (jps[i]->kp.addr)
1778                        __unregister_kprobe_bottom(&jps[i]->kp);
1779        }
1780}
1781EXPORT_SYMBOL_GPL(unregister_jprobes);
1782
1783#ifdef CONFIG_KRETPROBES
1784/*
1785 * This kprobe pre_handler is registered with every kretprobe. When probe
1786 * hits it will set up the return probe.
1787 */
1788static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1789                                           struct pt_regs *regs)
1790{
1791        struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1792        unsigned long hash, flags = 0;
1793        struct kretprobe_instance *ri;
1794
1795        /*TODO: consider to only swap the RA after the last pre_handler fired */
1796        hash = hash_ptr(current, KPROBE_HASH_BITS);
1797        raw_spin_lock_irqsave(&rp->lock, flags);
1798        if (!hlist_empty(&rp->free_instances)) {
1799                ri = hlist_entry(rp->free_instances.first,
1800                                struct kretprobe_instance, hlist);
1801                hlist_del(&ri->hlist);
1802                raw_spin_unlock_irqrestore(&rp->lock, flags);
1803
1804                ri->rp = rp;
1805                ri->task = current;
1806
1807                if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1808                        raw_spin_lock_irqsave(&rp->lock, flags);
1809                        hlist_add_head(&ri->hlist, &rp->free_instances);
1810                        raw_spin_unlock_irqrestore(&rp->lock, flags);
1811                        return 0;
1812                }
1813
1814                arch_prepare_kretprobe(ri, regs);
1815
1816                /* XXX(hch): why is there no hlist_move_head? */
1817                INIT_HLIST_NODE(&ri->hlist);
1818                kretprobe_table_lock(hash, &flags);
1819                hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1820                kretprobe_table_unlock(hash, &flags);
1821        } else {
1822                rp->nmissed++;
1823                raw_spin_unlock_irqrestore(&rp->lock, flags);
1824        }
1825        return 0;
1826}
1827
1828int __kprobes register_kretprobe(struct kretprobe *rp)
1829{
1830        int ret = 0;
1831        struct kretprobe_instance *inst;
1832        int i;
1833        void *addr;
1834
1835        if (kretprobe_blacklist_size) {
1836                addr = kprobe_addr(&rp->kp);
1837                if (IS_ERR(addr))
1838                        return PTR_ERR(addr);
1839
1840                for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1841                        if (kretprobe_blacklist[i].addr == addr)
1842                                return -EINVAL;
1843                }
1844        }
1845
1846        rp->kp.pre_handler = pre_handler_kretprobe;
1847        rp->kp.post_handler = NULL;
1848        rp->kp.fault_handler = NULL;
1849        rp->kp.break_handler = NULL;
1850
1851        /* Pre-allocate memory for max kretprobe instances */
1852        if (rp->maxactive <= 0) {
1853#ifdef CONFIG_PREEMPT
1854                rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1855#else
1856                rp->maxactive = num_possible_cpus();
1857#endif
1858        }
1859        raw_spin_lock_init(&rp->lock);
1860        INIT_HLIST_HEAD(&rp->free_instances);
1861        for (i = 0; i < rp->maxactive; i++) {
1862                inst = kmalloc(sizeof(struct kretprobe_instance) +
1863                               rp->data_size, GFP_KERNEL);
1864                if (inst == NULL) {
1865                        free_rp_inst(rp);
1866                        return -ENOMEM;
1867                }
1868                INIT_HLIST_NODE(&inst->hlist);
1869                hlist_add_head(&inst->hlist, &rp->free_instances);
1870        }
1871
1872        rp->nmissed = 0;
1873        /* Establish function entry probe point */
1874        ret = register_kprobe(&rp->kp);
1875        if (ret != 0)
1876                free_rp_inst(rp);
1877        return ret;
1878}
1879EXPORT_SYMBOL_GPL(register_kretprobe);
1880
1881int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1882{
1883        int ret = 0, i;
1884
1885        if (num <= 0)
1886                return -EINVAL;
1887        for (i = 0; i < num; i++) {
1888                ret = register_kretprobe(rps[i]);
1889                if (ret < 0) {
1890                        if (i > 0)
1891                                unregister_kretprobes(rps, i);
1892                        break;
1893                }
1894        }
1895        return ret;
1896}
1897EXPORT_SYMBOL_GPL(register_kretprobes);
1898
1899void __kprobes unregister_kretprobe(struct kretprobe *rp)
1900{
1901        unregister_kretprobes(&rp, 1);
1902}
1903EXPORT_SYMBOL_GPL(unregister_kretprobe);
1904
1905void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1906{
1907        int i;
1908
1909        if (num <= 0)
1910                return;
1911        mutex_lock(&kprobe_mutex);
1912        for (i = 0; i < num; i++)
1913                if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1914                        rps[i]->kp.addr = NULL;
1915        mutex_unlock(&kprobe_mutex);
1916
1917        synchronize_sched();
1918        for (i = 0; i < num; i++) {
1919                if (rps[i]->kp.addr) {
1920                        __unregister_kprobe_bottom(&rps[i]->kp);
1921                        cleanup_rp_inst(rps[i]);
1922                }
1923        }
1924}
1925EXPORT_SYMBOL_GPL(unregister_kretprobes);
1926
1927#else /* CONFIG_KRETPROBES */
1928int __kprobes register_kretprobe(struct kretprobe *rp)
1929{
1930        return -ENOSYS;
1931}
1932EXPORT_SYMBOL_GPL(register_kretprobe);
1933
1934int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1935{
1936        return -ENOSYS;
1937}
1938EXPORT_SYMBOL_GPL(register_kretprobes);
1939
1940void __kprobes unregister_kretprobe(struct kretprobe *rp)
1941{
1942}
1943EXPORT_SYMBOL_GPL(unregister_kretprobe);
1944
1945void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1946{
1947}
1948EXPORT_SYMBOL_GPL(unregister_kretprobes);
1949
1950static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1951                                           struct pt_regs *regs)
1952{
1953        return 0;
1954}
1955
1956#endif /* CONFIG_KRETPROBES */
1957
1958/* Set the kprobe gone and remove its instruction buffer. */
1959static void __kprobes kill_kprobe(struct kprobe *p)
1960{
1961        struct kprobe *kp;
1962
1963        p->flags |= KPROBE_FLAG_GONE;
1964        if (kprobe_aggrprobe(p)) {
1965                /*
1966                 * If this is an aggr_kprobe, we have to list all the
1967                 * chained probes and mark them GONE.
1968                 */
1969                list_for_each_entry_rcu(kp, &p->list, list)
1970                        kp->flags |= KPROBE_FLAG_GONE;
1971                p->post_handler = NULL;
1972                p->break_handler = NULL;
1973                kill_optimized_kprobe(p);
1974        }
1975        /*
1976         * Here, we can remove insn_slot safely, because no thread calls
1977         * the original probed function (which will be freed soon) any more.
1978         */
1979        arch_remove_kprobe(p);
1980}
1981
1982/* Disable one kprobe */
1983int __kprobes disable_kprobe(struct kprobe *kp)
1984{
1985        int ret = 0;
1986
1987        mutex_lock(&kprobe_mutex);
1988
1989        /* Disable this kprobe */
1990        if (__disable_kprobe(kp) == NULL)
1991                ret = -EINVAL;
1992
1993        mutex_unlock(&kprobe_mutex);
1994        return ret;
1995}
1996EXPORT_SYMBOL_GPL(disable_kprobe);
1997
1998/* Enable one kprobe */
1999int __kprobes enable_kprobe(struct kprobe *kp)
2000{
2001        int ret = 0;
2002        struct kprobe *p;
2003
2004        mutex_lock(&kprobe_mutex);
2005
2006        /* Check whether specified probe is valid. */
2007        p = __get_valid_kprobe(kp);
2008        if (unlikely(p == NULL)) {
2009                ret = -EINVAL;
2010                goto out;
2011        }
2012
2013        if (kprobe_gone(kp)) {
2014                /* This kprobe has gone, we couldn't enable it. */
2015                ret = -EINVAL;
2016                goto out;
2017        }
2018
2019        if (p != kp)
2020                kp->flags &= ~KPROBE_FLAG_DISABLED;
2021
2022        if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2023                p->flags &= ~KPROBE_FLAG_DISABLED;
2024                arm_kprobe(p);
2025        }
2026out:
2027        mutex_unlock(&kprobe_mutex);
2028        return ret;
2029}
2030EXPORT_SYMBOL_GPL(enable_kprobe);
2031
2032void __kprobes dump_kprobe(struct kprobe *kp)
2033{
2034        printk(KERN_WARNING "Dumping kprobe:\n");
2035        printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2036               kp->symbol_name, kp->addr, kp->offset);
2037}
2038
2039/* Module notifier call back, checking kprobes on the module */
2040static int __kprobes kprobes_module_callback(struct notifier_block *nb,
2041                                             unsigned long val, void *data)
2042{
2043        struct module *mod = data;
2044        struct hlist_head *head;
2045        struct kprobe *p;
2046        unsigned int i;
2047        int checkcore = (val == MODULE_STATE_GOING);
2048
2049        if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2050                return NOTIFY_DONE;
2051
2052        /*
2053         * When MODULE_STATE_GOING was notified, both of module .text and
2054         * .init.text sections would be freed. When MODULE_STATE_LIVE was
2055         * notified, only .init.text section would be freed. We need to
2056         * disable kprobes which have been inserted in the sections.
2057         */
2058        mutex_lock(&kprobe_mutex);
2059        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2060                head = &kprobe_table[i];
2061                hlist_for_each_entry_rcu(p, head, hlist)
2062                        if (within_module_init((unsigned long)p->addr, mod) ||
2063                            (checkcore &&
2064                             within_module_core((unsigned long)p->addr, mod))) {
2065                                /*
2066                                 * The vaddr this probe is installed will soon
2067                                 * be vfreed buy not synced to disk. Hence,
2068                                 * disarming the breakpoint isn't needed.
2069                                 */
2070                                kill_kprobe(p);
2071                        }
2072        }
2073        mutex_unlock(&kprobe_mutex);
2074        return NOTIFY_DONE;
2075}
2076
2077static struct notifier_block kprobe_module_nb = {
2078        .notifier_call = kprobes_module_callback,
2079        .priority = 0
2080};
2081
2082static int __init init_kprobes(void)
2083{
2084        int i, err = 0;
2085        unsigned long offset = 0, size = 0;
2086        char *modname, namebuf[128];
2087        const char *symbol_name;
2088        void *addr;
2089        struct kprobe_blackpoint *kb;
2090
2091        /* FIXME allocate the probe table, currently defined statically */
2092        /* initialize all list heads */
2093        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2094                INIT_HLIST_HEAD(&kprobe_table[i]);
2095                INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2096                raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2097        }
2098
2099        /*
2100         * Lookup and populate the kprobe_blacklist.
2101         *
2102         * Unlike the kretprobe blacklist, we'll need to determine
2103         * the range of addresses that belong to the said functions,
2104         * since a kprobe need not necessarily be at the beginning
2105         * of a function.
2106         */
2107        for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
2108                kprobe_lookup_name(kb->name, addr);
2109                if (!addr)
2110                        continue;
2111
2112                kb->start_addr = (unsigned long)addr;
2113                symbol_name = kallsyms_lookup(kb->start_addr,
2114                                &size, &offset, &modname, namebuf);
2115                if (!symbol_name)
2116                        kb->range = 0;
2117                else
2118                        kb->range = size;
2119        }
2120
2121        if (kretprobe_blacklist_size) {
2122                /* lookup the function address from its name */
2123                for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2124                        kprobe_lookup_name(kretprobe_blacklist[i].name,
2125                                           kretprobe_blacklist[i].addr);
2126                        if (!kretprobe_blacklist[i].addr)
2127                                printk("kretprobe: lookup failed: %s\n",
2128                                       kretprobe_blacklist[i].name);
2129                }
2130        }
2131
2132#if defined(CONFIG_OPTPROBES)
2133#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2134        /* Init kprobe_optinsn_slots */
2135        kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2136#endif
2137        /* By default, kprobes can be optimized */
2138        kprobes_allow_optimization = true;
2139#endif
2140
2141        /* By default, kprobes are armed */
2142        kprobes_all_disarmed = false;
2143
2144        err = arch_init_kprobes();
2145        if (!err)
2146                err = register_die_notifier(&kprobe_exceptions_nb);
2147        if (!err)
2148                err = register_module_notifier(&kprobe_module_nb);
2149
2150        kprobes_initialized = (err == 0);
2151
2152        if (!err)
2153                init_test_probes();
2154        return err;
2155}
2156
2157#ifdef CONFIG_DEBUG_FS
2158static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
2159                const char *sym, int offset, char *modname, struct kprobe *pp)
2160{
2161        char *kprobe_type;
2162
2163        if (p->pre_handler == pre_handler_kretprobe)
2164                kprobe_type = "r";
2165        else if (p->pre_handler == setjmp_pre_handler)
2166                kprobe_type = "j";
2167        else
2168                kprobe_type = "k";
2169
2170        if (sym)
2171                seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2172                        p->addr, kprobe_type, sym, offset,
2173                        (modname ? modname : " "));
2174        else
2175                seq_printf(pi, "%p  %s  %p ",
2176                        p->addr, kprobe_type, p->addr);
2177
2178        if (!pp)
2179                pp = p;
2180        seq_printf(pi, "%s%s%s%s\n",
2181                (kprobe_gone(p) ? "[GONE]" : ""),
2182                ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2183                (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2184                (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2185}
2186
2187static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2188{
2189        return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2190}
2191
2192static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2193{
2194        (*pos)++;
2195        if (*pos >= KPROBE_TABLE_SIZE)
2196                return NULL;
2197        return pos;
2198}
2199
2200static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
2201{
2202        /* Nothing to do */
2203}
2204
2205static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
2206{
2207        struct hlist_head *head;
2208        struct kprobe *p, *kp;
2209        const char *sym = NULL;
2210        unsigned int i = *(loff_t *) v;
2211        unsigned long offset = 0;
2212        char *modname, namebuf[128];
2213
2214        head = &kprobe_table[i];
2215        preempt_disable();
2216        hlist_for_each_entry_rcu(p, head, hlist) {
2217                sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2218                                        &offset, &modname, namebuf);
2219                if (kprobe_aggrprobe(p)) {
2220                        list_for_each_entry_rcu(kp, &p->list, list)
2221                                report_probe(pi, kp, sym, offset, modname, p);
2222                } else
2223                        report_probe(pi, p, sym, offset, modname, NULL);
2224        }
2225        preempt_enable();
2226        return 0;
2227}
2228
2229static const struct seq_operations kprobes_seq_ops = {
2230        .start = kprobe_seq_start,
2231        .next  = kprobe_seq_next,
2232        .stop  = kprobe_seq_stop,
2233        .show  = show_kprobe_addr
2234};
2235
2236static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
2237{
2238        return seq_open(filp, &kprobes_seq_ops);
2239}
2240
2241static const struct file_operations debugfs_kprobes_operations = {
2242        .open           = kprobes_open,
2243        .read           = seq_read,
2244        .llseek         = seq_lseek,
2245        .release        = seq_release,
2246};
2247
2248static void __kprobes arm_all_kprobes(void)
2249{
2250        struct hlist_head *head;
2251        struct kprobe *p;
2252        unsigned int i;
2253
2254        mutex_lock(&kprobe_mutex);
2255
2256        /* If kprobes are armed, just return */
2257        if (!kprobes_all_disarmed)
2258                goto already_enabled;
2259
2260        /* Arming kprobes doesn't optimize kprobe itself */
2261        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2262                head = &kprobe_table[i];
2263                hlist_for_each_entry_rcu(p, head, hlist)
2264                        if (!kprobe_disabled(p))
2265                                arm_kprobe(p);
2266        }
2267
2268        kprobes_all_disarmed = false;
2269        printk(KERN_INFO "Kprobes globally enabled\n");
2270
2271already_enabled:
2272        mutex_unlock(&kprobe_mutex);
2273        return;
2274}
2275
2276static void __kprobes disarm_all_kprobes(void)
2277{
2278        struct hlist_head *head;
2279        struct kprobe *p;
2280        unsigned int i;
2281
2282        mutex_lock(&kprobe_mutex);
2283
2284        /* If kprobes are already disarmed, just return */
2285        if (kprobes_all_disarmed) {
2286                mutex_unlock(&kprobe_mutex);
2287                return;
2288        }
2289
2290        kprobes_all_disarmed = true;
2291        printk(KERN_INFO "Kprobes globally disabled\n");
2292
2293        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2294                head = &kprobe_table[i];
2295                hlist_for_each_entry_rcu(p, head, hlist) {
2296                        if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2297                                disarm_kprobe(p, false);
2298                }
2299        }
2300        mutex_unlock(&kprobe_mutex);
2301
2302        /* Wait for disarming all kprobes by optimizer */
2303        wait_for_kprobe_optimizer();
2304}
2305
2306/*
2307 * XXX: The debugfs bool file interface doesn't allow for callbacks
2308 * when the bool state is switched. We can reuse that facility when
2309 * available
2310 */
2311static ssize_t read_enabled_file_bool(struct file *file,
2312               char __user *user_buf, size_t count, loff_t *ppos)
2313{
2314        char buf[3];
2315
2316        if (!kprobes_all_disarmed)
2317                buf[0] = '1';
2318        else
2319                buf[0] = '0';
2320        buf[1] = '\n';
2321        buf[2] = 0x00;
2322        return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2323}
2324
2325static ssize_t write_enabled_file_bool(struct file *file,
2326               const char __user *user_buf, size_t count, loff_t *ppos)
2327{
2328        char buf[32];
2329        size_t buf_size;
2330
2331        buf_size = min(count, (sizeof(buf)-1));
2332        if (copy_from_user(buf, user_buf, buf_size))
2333                return -EFAULT;
2334
2335        switch (buf[0]) {
2336        case 'y':
2337        case 'Y':
2338        case '1':
2339                arm_all_kprobes();
2340                break;
2341        case 'n':
2342        case 'N':
2343        case '0':
2344                disarm_all_kprobes();
2345                break;
2346        }
2347
2348        return count;
2349}
2350
2351static const struct file_operations fops_kp = {
2352        .read =         read_enabled_file_bool,
2353        .write =        write_enabled_file_bool,
2354        .llseek =       default_llseek,
2355};
2356
2357static int __kprobes debugfs_kprobe_init(void)
2358{
2359        struct dentry *dir, *file;
2360        unsigned int value = 1;
2361
2362        dir = debugfs_create_dir("kprobes", NULL);
2363        if (!dir)
2364                return -ENOMEM;
2365
2366        file = debugfs_create_file("list", 0444, dir, NULL,
2367                                &debugfs_kprobes_operations);
2368        if (!file) {
2369                debugfs_remove(dir);
2370                return -ENOMEM;
2371        }
2372
2373        file = debugfs_create_file("enabled", 0600, dir,
2374                                        &value, &fops_kp);
2375        if (!file) {
2376                debugfs_remove(dir);
2377                return -ENOMEM;
2378        }
2379
2380        return 0;
2381}
2382
2383late_initcall(debugfs_kprobe_init);
2384#endif /* CONFIG_DEBUG_FS */
2385
2386module_init(init_kprobes);
2387
2388/* defined in arch/.../kernel/kprobes.c */
2389EXPORT_SYMBOL_GPL(jprobe_return);
2390
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