kernel/kprobes.c

   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
  70 static int kprobes_initialized;
  71 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  72 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
  73
  74 /* NOTE: change this value only with kprobe_mutex held */
  75 static bool kprobes_all_disarmed;
  76
  77 /* This protects kprobe_table and optimizing_list */
  78 static DEFINE_MUTEX(kprobe_mutex);
  79 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
  80 static struct {
  81         raw_spinlock_t lock ____cacheline_aligned_in_smp;
  82 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
  83
  84 static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
  85 {
  86         return &(kretprobe_table_locks[hash].lock);
  87 }
  88
  89 /* Blacklist -- list of struct kprobe_blacklist_entry */
  90 static LIST_HEAD(kprobe_blacklist);
  91
  92 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
  93 /*
  94  * kprobe->ainsn.insn points to the copy of the instruction to be
  95  * single-stepped. x86_64, POWER4 and above have no-exec support and
  96  * stepping on the instruction on a vmalloced/kmalloced/data page
  97  * is a recipe for disaster
  98  */
  99 struct kprobe_insn_page {
 100         struct list_head list;
 101         kprobe_opcode_t *insns;         /* Page of instruction slots */
 102         struct kprobe_insn_cache *cache;
 103         int nused;
 104         int ngarbage;
 105         char slot_used[];
 106 };
 107
 108 #define KPROBE_INSN_PAGE_SIZE(slots)                    \
 109         (offsetof(struct kprobe_insn_page, slot_used) + \
 110          (sizeof(char) * (slots)))
 111
 112 static int slots_per_page(struct kprobe_insn_cache *c)
 113 {
 114         return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
 115 }
 116
 117 enum kprobe_slot_state {
 118         SLOT_CLEAN = 0,
 119         SLOT_DIRTY = 1,
 120         SLOT_USED = 2,
 121 };
 122
 123 static void *alloc_insn_page(void)
 124 {
 125         return module_alloc(PAGE_SIZE);
 126 }
 127
 128 static void free_insn_page(void *page)
 129 {
 130         module_free(NULL, page);
 131 }
 132
 133 struct kprobe_insn_cache kprobe_insn_slots = {
 134         .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
 135         .alloc = alloc_insn_page,
 136         .free = free_insn_page,
 137         .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
 138         .insn_size = MAX_INSN_SIZE,
 139         .nr_garbage = 0,
 140 };
 141 static int collect_garbage_slots(struct kprobe_insn_cache *c);
 142
 143 /**
 144  * __get_insn_slot() - Find a slot on an executable page for an instruction.
 145  * We allocate an executable page if there's no room on existing ones.
 146  */
 147 kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
 148 {
 149         struct kprobe_insn_page *kip;
 150         kprobe_opcode_t *slot = NULL;
 151
 152         mutex_lock(&c->mutex);
 153  retry:
 154         list_for_each_entry(kip, &c->pages, list) {
 155                 if (kip->nused < slots_per_page(c)) {
 156                         int i;
 157                         for (i = 0; i < slots_per_page(c); i++) {
 158                                 if (kip->slot_used[i] == SLOT_CLEAN) {
 159                                         kip->slot_used[i] = SLOT_USED;
 160                                         kip->nused++;
 161                                         slot = kip->insns + (i * c->insn_size);
 162                                         goto out;
 163                                 }
 164                         }
 165                         /* kip->nused is broken. Fix it. */
 166                         kip->nused = slots_per_page(c);
 167                         WARN_ON(1);
 168                 }
 169         }
 170
 171         /* If there are any garbage slots, collect it and try again. */
 172         if (c->nr_garbage && collect_garbage_slots(c) == 0)
 173                 goto retry;
 174
 175         /* All out of space.  Need to allocate a new page. */
 176         kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
 177         if (!kip)
 178                 goto out;
 179
 180         /*
 181          * Use module_alloc so this page is within +/- 2GB of where the
 182          * kernel image and loaded module images reside. This is required
 183          * so x86_64 can correctly handle the %rip-relative fixups.
 184          */
 185         kip->insns = c->alloc();
 186         if (!kip->insns) {
 187                 kfree(kip);
 188                 goto out;
 189         }
 190         INIT_LIST_HEAD(&kip->list);
 191         memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
 192         kip->slot_used[0] = SLOT_USED;
 193         kip->nused = 1;
 194         kip->ngarbage = 0;
 195         kip->cache = c;
 196         list_add(&kip->list, &c->pages);
 197         slot = kip->insns;
 198 out:
 199         mutex_unlock(&c->mutex);
 200         return slot;
 201 }
 202
 203 /* Return 1 if all garbages are collected, otherwise 0. */
 204 static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
 205 {
 206         kip->slot_used[idx] = SLOT_CLEAN;
 207         kip->nused--;
 208         if (kip->nused == 0) {
 209                 /*
 210                  * Page is no longer in use.  Free it unless
 211                  * it's the last one.  We keep the last one
 212                  * so as not to have to set it up again the
 213                  * next time somebody inserts a probe.
 214                  */
 215                 if (!list_is_singular(&kip->list)) {
 216                         list_del(&kip->list);
 217                         kip->cache->free(kip->insns);
 218                         kfree(kip);
 219                 }
 220                 return 1;
 221         }
 222         return 0;
 223 }
 224
 225 static int collect_garbage_slots(struct kprobe_insn_cache *c)
 226 {
 227         struct kprobe_insn_page *kip, *next;
 228
 229         /* Ensure no-one is interrupted on the garbages */
 230         synchronize_sched();
 231
 232         list_for_each_entry_safe(kip, next, &c->pages, list) {
 233                 int i;
 234                 if (kip->ngarbage == 0)
 235                         continue;
 236                 kip->ngarbage = 0;      /* we will collect all garbages */
 237                 for (i = 0; i < slots_per_page(c); i++) {
 238                         if (kip->slot_used[i] == SLOT_DIRTY &&
 239                             collect_one_slot(kip, i))
 240                                 break;
 241                 }
 242         }
 243         c->nr_garbage = 0;
 244         return 0;
 245 }
 246
 247 void __free_insn_slot(struct kprobe_insn_cache *c,
 248                       kprobe_opcode_t *slot, int dirty)
 249 {
 250         struct kprobe_insn_page *kip;
 251
 252         mutex_lock(&c->mutex);
 253         list_for_each_entry(kip, &c->pages, list) {
 254                 long idx = ((long)slot - (long)kip->insns) /
 255                                 (c->insn_size * sizeof(kprobe_opcode_t));
 256                 if (idx >= 0 && idx < slots_per_page(c)) {
 257                         WARN_ON(kip->slot_used[idx] != SLOT_USED);
 258                         if (dirty) {
 259                                 kip->slot_used[idx] = SLOT_DIRTY;
 260                                 kip->ngarbage++;
 261                                 if (++c->nr_garbage > slots_per_page(c))
 262                                         collect_garbage_slots(c);
 263                         } else
 264                                 collect_one_slot(kip, idx);
 265                         goto out;
 266                 }
 267         }
 268         /* Could not free this slot. */
 269         WARN_ON(1);
 270 out:
 271         mutex_unlock(&c->mutex);
 272 }
 273
 274 #ifdef CONFIG_OPTPROBES
 275 /* For optimized_kprobe buffer */
 276 struct kprobe_insn_cache kprobe_optinsn_slots = {
 277         .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
 278         .alloc = alloc_insn_page,
 279         .free = free_insn_page,
 280         .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
 281         /* .insn_size is initialized later */
 282         .nr_garbage = 0,
 283 };
 284 #endif
 285 #endif
 286
 287 /* We have preemption disabled.. so it is safe to use __ versions */
 288 static inline void set_kprobe_instance(struct kprobe *kp)
 289 {
 290         __this_cpu_write(kprobe_instance, kp);
 291 }
 292
 293 static inline void reset_kprobe_instance(void)
 294 {
 295         __this_cpu_write(kprobe_instance, NULL);
 296 }
 297
 298 /*
 299  * This routine is called either:
 300  *      - under the kprobe_mutex - during kprobe_[un]register()
 301  *                              OR
 302  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
 303  */
 304 struct kprobe __kprobes *get_kprobe(void *addr)
 305 {
 306         struct hlist_head *head;
 307         struct kprobe *p;
 308
 309         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
 310         hlist_for_each_entry_rcu(p, head, hlist) {
 311                 if (p->addr == addr)
 312                         return p;
 313         }
 314
 315         return NULL;
 316 }
 317
 318 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
 319
 320 /* Return true if the kprobe is an aggregator */
 321 static inline int kprobe_aggrprobe(struct kprobe *p)
 322 {
 323         return p->pre_handler == aggr_pre_handler;
 324 }
 325
 326 /* Return true(!0) if the kprobe is unused */
 327 static inline int kprobe_unused(struct kprobe *p)
 328 {
 329         return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
 330                list_empty(&p->list);
 331 }
 332
 333 /*
 334  * Keep all fields in the kprobe consistent
 335  */
 336 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
 337 {
 338         memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
 339         memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
 340 }
 341
 342 #ifdef CONFIG_OPTPROBES
 343 /* NOTE: change this value only with kprobe_mutex held */
 344 static bool kprobes_allow_optimization;
 345
 346 /*
 347  * Call all pre_handler on the list, but ignores its return value.
 348  * This must be called from arch-dep optimized caller.
 349  */
 350 void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
 351 {
 352         struct kprobe *kp;
 353
 354         list_for_each_entry_rcu(kp, &p->list, list) {
 355                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 356                         set_kprobe_instance(kp);
 357                         kp->pre_handler(kp, regs);
 358                 }
 359                 reset_kprobe_instance();
 360         }
 361 }
 362
 363 /* Free optimized instructions and optimized_kprobe */
 364 static void free_aggr_kprobe(struct kprobe *p)
 365 {
 366         struct optimized_kprobe *op;
 367
 368         op = container_of(p, struct optimized_kprobe, kp);
 369         arch_remove_optimized_kprobe(op);
 370         arch_remove_kprobe(p);
 371         kfree(op);
 372 }
 373
 374 /* Return true(!0) if the kprobe is ready for optimization. */
 375 static inline int kprobe_optready(struct kprobe *p)
 376 {
 377         struct optimized_kprobe *op;
 378
 379         if (kprobe_aggrprobe(p)) {
 380                 op = container_of(p, struct optimized_kprobe, kp);
 381                 return arch_prepared_optinsn(&op->optinsn);
 382         }
 383
 384         return 0;
 385 }
 386
 387 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
 388 static inline int kprobe_disarmed(struct kprobe *p)
 389 {
 390         struct optimized_kprobe *op;
 391
 392         /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
 393         if (!kprobe_aggrprobe(p))
 394                 return kprobe_disabled(p);
 395
 396         op = container_of(p, struct optimized_kprobe, kp);
 397
 398         return kprobe_disabled(p) && list_empty(&op->list);
 399 }
 400
 401 /* Return true(!0) if the probe is queued on (un)optimizing lists */
 402 static int kprobe_queued(struct kprobe *p)
 403 {
 404         struct optimized_kprobe *op;
 405
 406         if (kprobe_aggrprobe(p)) {
 407                 op = container_of(p, struct optimized_kprobe, kp);
 408                 if (!list_empty(&op->list))
 409                         return 1;
 410         }
 411         return 0;
 412 }
 413
 414 /*
 415  * Return an optimized kprobe whose optimizing code replaces
 416  * instructions including addr (exclude breakpoint).
 417  */
 418 static struct kprobe *get_optimized_kprobe(unsigned long addr)
 419 {
 420         int i;
 421         struct kprobe *p = NULL;
 422         struct optimized_kprobe *op;
 423
 424         /* Don't check i == 0, since that is a breakpoint case. */
 425         for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
 426                 p = get_kprobe((void *)(addr - i));
 427
 428         if (p && kprobe_optready(p)) {
 429                 op = container_of(p, struct optimized_kprobe, kp);
 430                 if (arch_within_optimized_kprobe(op, addr))
 431                         return p;
 432         }
 433
 434         return NULL;
 435 }
 436
 437 /* Optimization staging list, protected by kprobe_mutex */
 438 static LIST_HEAD(optimizing_list);
 439 static LIST_HEAD(unoptimizing_list);
 440 static LIST_HEAD(freeing_list);
 441
 442 static void kprobe_optimizer(struct work_struct *work);
 443 static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
 444 #define OPTIMIZE_DELAY 5
 445
 446 /*
 447  * Optimize (replace a breakpoint with a jump) kprobes listed on
 448  * optimizing_list.
 449  */
 450 static void do_optimize_kprobes(void)
 451 {
 452         /* Optimization never be done when disarmed */
 453         if (kprobes_all_disarmed || !kprobes_allow_optimization ||
 454             list_empty(&optimizing_list))
 455                 return;
 456
 457         /*
 458          * The optimization/unoptimization refers online_cpus via
 459          * stop_machine() and cpu-hotplug modifies online_cpus.
 460          * And same time, text_mutex will be held in cpu-hotplug and here.
 461          * This combination can cause a deadlock (cpu-hotplug try to lock
 462          * text_mutex but stop_machine can not be done because online_cpus
 463          * has been changed)
 464          * To avoid this deadlock, we need to call get_online_cpus()
 465          * for preventing cpu-hotplug outside of text_mutex locking.
 466          */
 467         get_online_cpus();
 468         mutex_lock(&text_mutex);
 469         arch_optimize_kprobes(&optimizing_list);
 470         mutex_unlock(&text_mutex);
 471         put_online_cpus();
 472 }
 473
 474 /*
 475  * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
 476  * if need) kprobes listed on unoptimizing_list.
 477  */
 478 static void do_unoptimize_kprobes(void)
 479 {
 480         struct optimized_kprobe *op, *tmp;
 481
 482         /* Unoptimization must be done anytime */
 483         if (list_empty(&unoptimizing_list))
 484                 return;
 485
 486         /* Ditto to do_optimize_kprobes */
 487         get_online_cpus();
 488         mutex_lock(&text_mutex);
 489         arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
 490         /* Loop free_list for disarming */
 491         list_for_each_entry_safe(op, tmp, &freeing_list, list) {
 492                 /* Disarm probes if marked disabled */
 493                 if (kprobe_disabled(&op->kp))
 494                         arch_disarm_kprobe(&op->kp);
 495                 if (kprobe_unused(&op->kp)) {
 496                         /*
 497                          * Remove unused probes from hash list. After waiting
 498                          * for synchronization, these probes are reclaimed.
 499                          * (reclaiming is done by do_free_cleaned_kprobes.)
 500                          */
 501                         hlist_del_rcu(&op->kp.hlist);
 502                 } else
 503                         list_del_init(&op->list);
 504         }
 505         mutex_unlock(&text_mutex);
 506         put_online_cpus();
 507 }
 508
 509 /* Reclaim all kprobes on the free_list */
 510 static void do_free_cleaned_kprobes(void)
 511 {
 512         struct optimized_kprobe *op, *tmp;
 513
 514         list_for_each_entry_safe(op, tmp, &freeing_list, list) {
 515                 BUG_ON(!kprobe_unused(&op->kp));
 516                 list_del_init(&op->list);
 517                 free_aggr_kprobe(&op->kp);
 518         }
 519 }
 520
 521 /* Start optimizer after OPTIMIZE_DELAY passed */
 522 static void kick_kprobe_optimizer(void)
 523 {
 524         schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
 525 }
 526
 527 /* Kprobe jump optimizer */
 528 static void kprobe_optimizer(struct work_struct *work)
 529 {
 530         mutex_lock(&kprobe_mutex);
 531         /* Lock modules while optimizing kprobes */
 532         mutex_lock(&module_mutex);
 533
 534         /*
 535          * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
 536          * kprobes before waiting for quiesence period.
 537          */
 538         do_unoptimize_kprobes();
 539
 540         /*
 541          * Step 2: Wait for quiesence period to ensure all running interrupts
 542          * are done. Because optprobe may modify multiple instructions
 543          * there is a chance that Nth instruction is interrupted. In that
 544          * case, running interrupt can return to 2nd-Nth byte of jump
 545          * instruction. This wait is for avoiding it.
 546          */
 547         synchronize_sched();
 548
 549         /* Step 3: Optimize kprobes after quiesence period */
 550         do_optimize_kprobes();
 551
 552         /* Step 4: Free cleaned kprobes after quiesence period */
 553         do_free_cleaned_kprobes();
 554
 555         mutex_unlock(&module_mutex);
 556         mutex_unlock(&kprobe_mutex);
 557
 558         /* Step 5: Kick optimizer again if needed */
 559         if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
 560                 kick_kprobe_optimizer();
 561 }
 562
 563 /* Wait for completing optimization and unoptimization */
 564 static void wait_for_kprobe_optimizer(void)
 565 {
 566         mutex_lock(&kprobe_mutex);
 567
 568         while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
 569                 mutex_unlock(&kprobe_mutex);
 570
 571                 /* this will also make optimizing_work execute immmediately */
 572                 flush_delayed_work(&optimizing_work);
 573                 /* @optimizing_work might not have been queued yet, relax */
 574                 cpu_relax();
 575
 576                 mutex_lock(&kprobe_mutex);
 577         }
 578
 579         mutex_unlock(&kprobe_mutex);
 580 }
 581
 582 /* Optimize kprobe if p is ready to be optimized */
 583 static void optimize_kprobe(struct kprobe *p)
 584 {
 585         struct optimized_kprobe *op;
 586
 587         /* Check if the kprobe is disabled or not ready for optimization. */
 588         if (!kprobe_optready(p) || !kprobes_allow_optimization ||
 589             (kprobe_disabled(p) || kprobes_all_disarmed))
 590                 return;
 591
 592         /* Both of break_handler and post_handler are not supported. */
 593         if (p->break_handler || p->post_handler)
 594                 return;
 595
 596         op = container_of(p, struct optimized_kprobe, kp);
 597
 598         /* Check there is no other kprobes at the optimized instructions */
 599         if (arch_check_optimized_kprobe(op) < 0)
 600                 return;
 601
 602         /* Check if it is already optimized. */
 603         if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
 604                 return;
 605         op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
 606
 607         if (!list_empty(&op->list))
 608                 /* This is under unoptimizing. Just dequeue the probe */
 609                 list_del_init(&op->list);
 610         else {
 611                 list_add(&op->list, &optimizing_list);
 612                 kick_kprobe_optimizer();
 613         }
 614 }
 615
 616 /* Short cut to direct unoptimizing */
 617 static void force_unoptimize_kprobe(struct optimized_kprobe *op)
 618 {
 619         get_online_cpus();
 620         arch_unoptimize_kprobe(op);
 621         put_online_cpus();
 622         if (kprobe_disabled(&op->kp))
 623                 arch_disarm_kprobe(&op->kp);
 624 }
 625
 626 /* Unoptimize a kprobe if p is optimized */
 627 static void unoptimize_kprobe(struct kprobe *p, bool force)
 628 {
 629         struct optimized_kprobe *op;
 630
 631         if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
 632                 return; /* This is not an optprobe nor optimized */
 633
 634         op = container_of(p, struct optimized_kprobe, kp);
 635         if (!kprobe_optimized(p)) {
 636                 /* Unoptimized or unoptimizing case */
 637                 if (force && !list_empty(&op->list)) {
 638                         /*
 639                          * Only if this is unoptimizing kprobe and forced,
 640                          * forcibly unoptimize it. (No need to unoptimize
 641                          * unoptimized kprobe again :)
 642                          */
 643                         list_del_init(&op->list);
 644                         force_unoptimize_kprobe(op);
 645                 }
 646                 return;
 647         }
 648
 649         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 650         if (!list_empty(&op->list)) {
 651                 /* Dequeue from the optimization queue */
 652                 list_del_init(&op->list);
 653                 return;
 654         }
 655         /* Optimized kprobe case */
 656         if (force)
 657                 /* Forcibly update the code: this is a special case */
 658                 force_unoptimize_kprobe(op);
 659         else {
 660                 list_add(&op->list, &unoptimizing_list);
 661                 kick_kprobe_optimizer();
 662         }
 663 }
 664
 665 /* Cancel unoptimizing for reusing */
 666 static void reuse_unused_kprobe(struct kprobe *ap)
 667 {
 668         struct optimized_kprobe *op;
 669
 670         BUG_ON(!kprobe_unused(ap));
 671         /*
 672          * Unused kprobe MUST be on the way of delayed unoptimizing (means
 673          * there is still a relative jump) and disabled.
 674          */
 675         op = container_of(ap, struct optimized_kprobe, kp);
 676         if (unlikely(list_empty(&op->list)))
 677                 printk(KERN_WARNING "Warning: found a stray unused "
 678                         "aggrprobe@%p\n", ap->addr);
 679         /* Enable the probe again */
 680         ap->flags &= ~KPROBE_FLAG_DISABLED;
 681         /* Optimize it again (remove from op->list) */
 682         BUG_ON(!kprobe_optready(ap));
 683         optimize_kprobe(ap);
 684 }
 685
 686 /* Remove optimized instructions */
 687 static void kill_optimized_kprobe(struct kprobe *p)
 688 {
 689         struct optimized_kprobe *op;
 690
 691         op = container_of(p, struct optimized_kprobe, kp);
 692         if (!list_empty(&op->list))
 693                 /* Dequeue from the (un)optimization queue */
 694                 list_del_init(&op->list);
 695         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 696
 697         if (kprobe_unused(p)) {
 698                 /* Enqueue if it is unused */
 699                 list_add(&op->list, &freeing_list);
 700                 /*
 701                  * Remove unused probes from the hash list. After waiting
 702                  * for synchronization, this probe is reclaimed.
 703                  * (reclaiming is done by do_free_cleaned_kprobes().)
 704                  */
 705                 hlist_del_rcu(&op->kp.hlist);
 706         }
 707
 708         /* Don't touch the code, because it is already freed. */
 709         arch_remove_optimized_kprobe(op);
 710 }
 711
 712 /* Try to prepare optimized instructions */
 713 static void prepare_optimized_kprobe(struct kprobe *p)
 714 {
 715         struct optimized_kprobe *op;
 716
 717         op = container_of(p, struct optimized_kprobe, kp);
 718         arch_prepare_optimized_kprobe(op);
 719 }
 720
 721 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
 722 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 723 {
 724         struct optimized_kprobe *op;
 725
 726         op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
 727         if (!op)
 728                 return NULL;
 729
 730         INIT_LIST_HEAD(&op->list);
 731         op->kp.addr = p->addr;
 732         arch_prepare_optimized_kprobe(op);
 733
 734         return &op->kp;
 735 }
 736
 737 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
 738
 739 /*
 740  * Prepare an optimized_kprobe and optimize it
 741  * NOTE: p must be a normal registered kprobe
 742  */
 743 static void try_to_optimize_kprobe(struct kprobe *p)
 744 {
 745         struct kprobe *ap;
 746         struct optimized_kprobe *op;
 747
 748         /* Impossible to optimize ftrace-based kprobe */
 749         if (kprobe_ftrace(p))
 750                 return;
 751
 752         /* For preparing optimization, jump_label_text_reserved() is called */
 753         jump_label_lock();
 754         mutex_lock(&text_mutex);
 755
 756         ap = alloc_aggr_kprobe(p);
 757         if (!ap)
 758                 goto out;
 759
 760         op = container_of(ap, struct optimized_kprobe, kp);
 761         if (!arch_prepared_optinsn(&op->optinsn)) {
 762                 /* If failed to setup optimizing, fallback to kprobe */
 763                 arch_remove_optimized_kprobe(op);
 764                 kfree(op);
 765                 goto out;
 766         }
 767
 768         init_aggr_kprobe(ap, p);
 769         optimize_kprobe(ap);    /* This just kicks optimizer thread */
 770
 771 out:
 772         mutex_unlock(&text_mutex);
 773         jump_label_unlock();
 774 }
 775
 776 #ifdef CONFIG_SYSCTL
 777 static void optimize_all_kprobes(void)
 778 {
 779         struct hlist_head *head;
 780         struct kprobe *p;
 781         unsigned int i;
 782
 783         mutex_lock(&kprobe_mutex);
 784         /* If optimization is already allowed, just return */
 785         if (kprobes_allow_optimization)
 786                 goto out;
 787
 788         kprobes_allow_optimization = true;
 789         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 790                 head = &kprobe_table[i];
 791                 hlist_for_each_entry_rcu(p, head, hlist)
 792                         if (!kprobe_disabled(p))
 793                                 optimize_kprobe(p);
 794         }
 795         printk(KERN_INFO "Kprobes globally optimized\n");
 796 out:
 797         mutex_unlock(&kprobe_mutex);
 798 }
 799
 800 static void unoptimize_all_kprobes(void)
 801 {
 802         struct hlist_head *head;
 803         struct kprobe *p;
 804         unsigned int i;
 805
 806         mutex_lock(&kprobe_mutex);
 807         /* If optimization is already prohibited, just return */
 808         if (!kprobes_allow_optimization) {
 809                 mutex_unlock(&kprobe_mutex);
 810                 return;
 811         }
 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, head, hlist) {
 817                         if (!kprobe_disabled(p))
 818                                 unoptimize_kprobe(p, false);
 819                 }
 820         }
 821         mutex_unlock(&kprobe_mutex);
 822
 823         /* Wait for unoptimizing completion */
 824         wait_for_kprobe_optimizer();
 825         printk(KERN_INFO "Kprobes globally unoptimized\n");
 826 }
 827
 828 static DEFINE_MUTEX(kprobe_sysctl_mutex);
 829 int sysctl_kprobes_optimization;
 830 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
 831                                       void __user *buffer, size_t *length,
 832                                       loff_t *ppos)
 833 {
 834         int ret;
 835
 836         mutex_lock(&kprobe_sysctl_mutex);
 837         sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
 838         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
 839
 840         if (sysctl_kprobes_optimization)
 841                 optimize_all_kprobes();
 842         else
 843                 unoptimize_all_kprobes();
 844         mutex_unlock(&kprobe_sysctl_mutex);
 845
 846         return ret;
 847 }
 848 #endif /* CONFIG_SYSCTL */
 849
 850 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
 851 static void __arm_kprobe(struct kprobe *p)
 852 {
 853         struct kprobe *_p;
 854
 855         /* Check collision with other optimized kprobes */
 856         _p = get_optimized_kprobe((unsigned long)p->addr);
 857         if (unlikely(_p))
 858                 /* Fallback to unoptimized kprobe */
 859                 unoptimize_kprobe(_p, true);
 860
 861         arch_arm_kprobe(p);
 862         optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
 863 }
 864
 865 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
 866 static void __disarm_kprobe(struct kprobe *p, bool reopt)
 867 {
 868         struct kprobe *_p;
 869
 870         unoptimize_kprobe(p, false);    /* Try to unoptimize */
 871
 872         if (!kprobe_queued(p)) {
 873                 arch_disarm_kprobe(p);
 874                 /* If another kprobe was blocked, optimize it. */
 875                 _p = get_optimized_kprobe((unsigned long)p->addr);
 876                 if (unlikely(_p) && reopt)
 877                         optimize_kprobe(_p);
 878         }
 879         /* TODO: reoptimize others after unoptimized this probe */
 880 }
 881
 882 #else /* !CONFIG_OPTPROBES */
 883
 884 #define optimize_kprobe(p)                      do {} while (0)
 885 #define unoptimize_kprobe(p, f)                 do {} while (0)
 886 #define kill_optimized_kprobe(p)                do {} while (0)
 887 #define prepare_optimized_kprobe(p)             do {} while (0)
 888 #define try_to_optimize_kprobe(p)               do {} while (0)
 889 #define __arm_kprobe(p)                         arch_arm_kprobe(p)
 890 #define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
 891 #define kprobe_disarmed(p)                      kprobe_disabled(p)
 892 #define wait_for_kprobe_optimizer()             do {} while (0)
 893
 894 /* There should be no unused kprobes can be reused without optimization */
 895 static void reuse_unused_kprobe(struct kprobe *ap)
 896 {
 897         printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
 898         BUG_ON(kprobe_unused(ap));
 899 }
 900
 901 static void free_aggr_kprobe(struct kprobe *p)
 902 {
 903         arch_remove_kprobe(p);
 904         kfree(p);
 905 }
 906
 907 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 908 {
 909         return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
 910 }
 911 #endif /* CONFIG_OPTPROBES */
 912
 913 #ifdef CONFIG_KPROBES_ON_FTRACE
 914 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
 915         .func = kprobe_ftrace_handler,
 916         .flags = FTRACE_OPS_FL_SAVE_REGS,
 917 };
 918 static int kprobe_ftrace_enabled;
 919
 920 /* Must ensure p->addr is really on ftrace */
 921 static int prepare_kprobe(struct kprobe *p)
 922 {
 923         if (!kprobe_ftrace(p))
 924                 return arch_prepare_kprobe(p);
 925
 926         return arch_prepare_kprobe_ftrace(p);
 927 }
 928
 929 /* Caller must lock kprobe_mutex */
 930 static void arm_kprobe_ftrace(struct kprobe *p)
 931 {
 932         int ret;
 933
 934         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 935                                    (unsigned long)p->addr, 0, 0);
 936         WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 937         kprobe_ftrace_enabled++;
 938         if (kprobe_ftrace_enabled == 1) {
 939                 ret = register_ftrace_function(&kprobe_ftrace_ops);
 940                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 941         }
 942 }
 943
 944 /* Caller must lock kprobe_mutex */
 945 static void disarm_kprobe_ftrace(struct kprobe *p)
 946 {
 947         int ret;
 948
 949         kprobe_ftrace_enabled--;
 950         if (kprobe_ftrace_enabled == 0) {
 951                 ret = unregister_ftrace_function(&kprobe_ftrace_ops);
 952                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 953         }
 954         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 955                            (unsigned long)p->addr, 1, 0);
 956         WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 957 }
 958 #else   /* !CONFIG_KPROBES_ON_FTRACE */
 959 #define prepare_kprobe(p)       arch_prepare_kprobe(p)
 960 #define arm_kprobe_ftrace(p)    do {} while (0)
 961 #define disarm_kprobe_ftrace(p) do {} while (0)
 962 #endif
 963
 964 /* Arm a kprobe with text_mutex */
 965 static void arm_kprobe(struct kprobe *kp)
 966 {
 967         if (unlikely(kprobe_ftrace(kp))) {
 968                 arm_kprobe_ftrace(kp);
 969                 return;
 970         }
 971         /*
 972          * Here, since __arm_kprobe() doesn't use stop_machine(),
 973          * this doesn't cause deadlock on text_mutex. So, we don't
 974          * need get_online_cpus().
 975          */
 976         mutex_lock(&text_mutex);
 977         __arm_kprobe(kp);
 978         mutex_unlock(&text_mutex);
 979 }
 980
 981 /* Disarm a kprobe with text_mutex */
 982 static void disarm_kprobe(struct kprobe *kp, bool reopt)
 983 {
 984         if (unlikely(kprobe_ftrace(kp))) {
 985                 disarm_kprobe_ftrace(kp);
 986                 return;
 987         }
 988         /* Ditto */
 989         mutex_lock(&text_mutex);
 990         __disarm_kprobe(kp, reopt);
 991         mutex_unlock(&text_mutex);
 992 }
 993
 994 /*
 995  * Aggregate handlers for multiple kprobes support - these handlers
 996  * take care of invoking the individual kprobe handlers on p->list
 997  */
 998 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
 999 {
1000         struct kprobe *kp;
1001
1002         list_for_each_entry_rcu(kp, &p->list, list) {
1003                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1004                         set_kprobe_instance(kp);
1005                         if (kp->pre_handler(kp, regs))
1006                                 return 1;
1007                 }
1008                 reset_kprobe_instance();
1009         }
1010         return 0;
1011 }
1012
1013 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1014                                         unsigned long flags)
1015 {
1016         struct kprobe *kp;
1017
1018         list_for_each_entry_rcu(kp, &p->list, list) {
1019                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1020                         set_kprobe_instance(kp);
1021                         kp->post_handler(kp, regs, flags);
1022                         reset_kprobe_instance();
1023                 }
1024         }
1025 }
1026
1027 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1028                                         int trapnr)
1029 {
1030         struct kprobe *cur = __this_cpu_read(kprobe_instance);
1031
1032         /*
1033          * if we faulted "during" the execution of a user specified
1034          * probe handler, invoke just that probe's fault handler
1035          */
1036         if (cur && cur->fault_handler) {
1037                 if (cur->fault_handler(cur, regs, trapnr))
1038                         return 1;
1039         }
1040         return 0;
1041 }
1042
1043 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
1044 {
1045         struct kprobe *cur = __this_cpu_read(kprobe_instance);
1046         int ret = 0;
1047
1048         if (cur && cur->break_handler) {
1049                 if (cur->break_handler(cur, regs))
1050                         ret = 1;
1051         }
1052         reset_kprobe_instance();
1053         return ret;
1054 }
1055
1056 /* Walks the list and increments nmissed count for multiprobe case */
1057 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
1058 {
1059         struct kprobe *kp;
1060         if (!kprobe_aggrprobe(p)) {
1061                 p->nmissed++;
1062         } else {
1063                 list_for_each_entry_rcu(kp, &p->list, list)
1064                         kp->nmissed++;
1065         }
1066         return;
1067 }
1068
1069 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
1070                                 struct hlist_head *head)
1071 {
1072         struct kretprobe *rp = ri->rp;
1073
1074         /* remove rp inst off the rprobe_inst_table */
1075         hlist_del(&ri->hlist);
1076         INIT_HLIST_NODE(&ri->hlist);
1077         if (likely(rp)) {
1078                 raw_spin_lock(&rp->lock);
1079                 hlist_add_head(&ri->hlist, &rp->free_instances);
1080                 raw_spin_unlock(&rp->lock);
1081         } else
1082                 /* Unregistering */
1083                 hlist_add_head(&ri->hlist, head);
1084 }
1085
1086 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
1087                          struct hlist_head **head, unsigned long *flags)
1088 __acquires(hlist_lock)
1089 {
1090         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1091         raw_spinlock_t *hlist_lock;
1092
1093         *head = &kretprobe_inst_table[hash];
1094         hlist_lock = kretprobe_table_lock_ptr(hash);
1095         raw_spin_lock_irqsave(hlist_lock, *flags);
1096 }
1097
1098 static void __kprobes kretprobe_table_lock(unsigned long hash,
1099         unsigned long *flags)
1100 __acquires(hlist_lock)
1101 {
1102         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1103         raw_spin_lock_irqsave(hlist_lock, *flags);
1104 }
1105
1106 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
1107         unsigned long *flags)
1108 __releases(hlist_lock)
1109 {
1110         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1111         raw_spinlock_t *hlist_lock;
1112
1113         hlist_lock = kretprobe_table_lock_ptr(hash);
1114         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1115 }
1116
1117 static void __kprobes kretprobe_table_unlock(unsigned long hash,
1118        unsigned long *flags)
1119 __releases(hlist_lock)
1120 {
1121         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1122         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1123 }
1124
1125 /*
1126  * This function is called from finish_task_switch when task tk becomes dead,
1127  * so that we can recycle any function-return probe instances associated
1128  * with this task. These left over instances represent probed functions
1129  * that have been called but will never return.
1130  */
1131 void __kprobes kprobe_flush_task(struct task_struct *tk)
1132 {
1133         struct kretprobe_instance *ri;
1134         struct hlist_head *head, empty_rp;
1135         struct hlist_node *tmp;
1136         unsigned long hash, flags = 0;
1137
1138         if (unlikely(!kprobes_initialized))
1139                 /* Early boot.  kretprobe_table_locks not yet initialized. */
1140                 return;
1141
1142         INIT_HLIST_HEAD(&empty_rp);
1143         hash = hash_ptr(tk, KPROBE_HASH_BITS);
1144         head = &kretprobe_inst_table[hash];
1145         kretprobe_table_lock(hash, &flags);
1146         hlist_for_each_entry_safe(ri, tmp, head, hlist) {
1147                 if (ri->task == tk)
1148                         recycle_rp_inst(ri, &empty_rp);
1149         }
1150         kretprobe_table_unlock(hash, &flags);
1151         hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
1152                 hlist_del(&ri->hlist);
1153                 kfree(ri);
1154         }
1155 }
1156
1157 static inline void free_rp_inst(struct kretprobe *rp)
1158 {
1159         struct kretprobe_instance *ri;
1160         struct hlist_node *next;
1161
1162         hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1163                 hlist_del(&ri->hlist);
1164                 kfree(ri);
1165         }
1166 }
1167
1168 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
1169 {
1170         unsigned long flags, hash;
1171         struct kretprobe_instance *ri;
1172         struct hlist_node *next;
1173         struct hlist_head *head;
1174
1175         /* No race here */
1176         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1177                 kretprobe_table_lock(hash, &flags);
1178                 head = &kretprobe_inst_table[hash];
1179                 hlist_for_each_entry_safe(ri, next, head, hlist) {
1180                         if (ri->rp == rp)
1181                                 ri->rp = NULL;
1182                 }
1183                 kretprobe_table_unlock(hash, &flags);
1184         }
1185         free_rp_inst(rp);
1186 }
1187
1188 /*
1189 * Add the new probe to ap->list. Fail if this is the
1190 * second jprobe at the address - two jprobes can't coexist
1191 */
1192 static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1193 {
1194         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1195
1196         if (p->break_handler || p->post_handler)
1197                 unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1198
1199         if (p->break_handler) {
1200                 if (ap->break_handler)
1201                         return -EEXIST;
1202                 list_add_tail_rcu(&p->list, &ap->list);
1203                 ap->break_handler = aggr_break_handler;
1204         } else
1205                 list_add_rcu(&p->list, &ap->list);
1206         if (p->post_handler && !ap->post_handler)
1207                 ap->post_handler = aggr_post_handler;
1208
1209         return 0;
1210 }
1211
1212 /*
1213  * Fill in the required fields of the "manager kprobe". Replace the
1214  * earlier kprobe in the hlist with the manager kprobe
1215  */
1216 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1217 {
1218         /* Copy p's insn slot to ap */
1219         copy_kprobe(p, ap);
1220         flush_insn_slot(ap);
1221         ap->addr = p->addr;
1222         ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1223         ap->pre_handler = aggr_pre_handler;
1224         ap->fault_handler = aggr_fault_handler;
1225         /* We don't care the kprobe which has gone. */
1226         if (p->post_handler && !kprobe_gone(p))
1227                 ap->post_handler = aggr_post_handler;
1228         if (p->break_handler && !kprobe_gone(p))
1229                 ap->break_handler = aggr_break_handler;
1230
1231         INIT_LIST_HEAD(&ap->list);
1232         INIT_HLIST_NODE(&ap->hlist);
1233
1234         list_add_rcu(&p->list, &ap->list);
1235         hlist_replace_rcu(&p->hlist, &ap->hlist);
1236 }
1237
1238 /*
1239  * This is the second or subsequent kprobe at the address - handle
1240  * the intricacies
1241  */
1242 static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
1243 {
1244         int ret = 0;
1245         struct kprobe *ap = orig_p;
1246
1247         /* For preparing optimization, jump_label_text_reserved() is called */
1248         jump_label_lock();
1249         /*
1250          * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1251          * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1252          */
1253         get_online_cpus();
1254         mutex_lock(&text_mutex);
1255
1256         if (!kprobe_aggrprobe(orig_p)) {
1257                 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1258                 ap = alloc_aggr_kprobe(orig_p);
1259                 if (!ap) {
1260                         ret = -ENOMEM;
1261                         goto out;
1262                 }
1263                 init_aggr_kprobe(ap, orig_p);
1264         } else if (kprobe_unused(ap))
1265                 /* This probe is going to die. Rescue it */
1266                 reuse_unused_kprobe(ap);
1267
1268         if (kprobe_gone(ap)) {
1269                 /*
1270                  * Attempting to insert new probe at the same location that
1271                  * had a probe in the module vaddr area which already
1272                  * freed. So, the instruction slot has already been
1273                  * released. We need a new slot for the new probe.
1274                  */
1275                 ret = arch_prepare_kprobe(ap);
1276                 if (ret)
1277                         /*
1278                          * Even if fail to allocate new slot, don't need to
1279                          * free aggr_probe. It will be used next time, or
1280                          * freed by unregister_kprobe.
1281                          */
1282                         goto out;
1283
1284                 /* Prepare optimized instructions if possible. */
1285                 prepare_optimized_kprobe(ap);
1286
1287                 /*
1288                  * Clear gone flag to prevent allocating new slot again, and
1289                  * set disabled flag because it is not armed yet.
1290                  */
1291                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1292                             | KPROBE_FLAG_DISABLED;
1293         }
1294
1295         /* Copy ap's insn slot to p */
1296         copy_kprobe(ap, p);
1297         ret = add_new_kprobe(ap, p);
1298
1299 out:
1300         mutex_unlock(&text_mutex);
1301         put_online_cpus();
1302         jump_label_unlock();
1303
1304         if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1305                 ap->flags &= ~KPROBE_FLAG_DISABLED;
1306                 if (!kprobes_all_disarmed)
1307                         /* Arm the breakpoint again. */
1308                         arm_kprobe(ap);
1309         }
1310         return ret;
1311 }
1312
1313 bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1314 {
1315         /* The __kprobes marked functions and entry code must not be probed */
1316         return addr >= (unsigned long)__kprobes_text_start &&
1317                addr < (unsigned long)__kprobes_text_end;
1318 }
1319
1320 static bool within_kprobe_blacklist(unsigned long addr)
1321 {
1322         struct kprobe_blacklist_entry *ent;
1323
1324         if (arch_within_kprobe_blacklist(addr))
1325                 return true;
1326         /*
1327          * If there exists a kprobe_blacklist, verify and
1328          * fail any probe registration in the prohibited area
1329          */
1330         list_for_each_entry(ent, &kprobe_blacklist, list) {
1331                 if (addr >= ent->start_addr && addr < ent->end_addr)
1332                         return true;
1333         }
1334
1335         return false;
1336 }
1337
1338 /*
1339  * If we have a symbol_name argument, look it up and add the offset field
1340  * to it. This way, we can specify a relative address to a symbol.
1341  * This returns encoded errors if it fails to look up symbol or invalid
1342  * combination of parameters.
1343  */
1344 static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1345 {
1346         kprobe_opcode_t *addr = p->addr;
1347
1348         if ((p->symbol_name && p->addr) ||
1349             (!p->symbol_name && !p->addr))
1350                 goto invalid;
1351
1352         if (p->symbol_name) {
1353                 kprobe_lookup_name(p->symbol_name, addr);
1354                 if (!addr)
1355                         return ERR_PTR(-ENOENT);
1356         }
1357
1358         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1359         if (addr)
1360                 return addr;
1361
1362 invalid:
1363         return ERR_PTR(-EINVAL);
1364 }
1365
1366 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1367 static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1368 {
1369         struct kprobe *ap, *list_p;
1370
1371         ap = get_kprobe(p->addr);
1372         if (unlikely(!ap))
1373                 return NULL;
1374
1375         if (p != ap) {
1376                 list_for_each_entry_rcu(list_p, &ap->list, list)
1377                         if (list_p == p)
1378                         /* kprobe p is a valid probe */
1379                                 goto valid;
1380                 return NULL;
1381         }
1382 valid:
1383         return ap;
1384 }
1385
1386 /* Return error if the kprobe is being re-registered */
1387 static inline int check_kprobe_rereg(struct kprobe *p)
1388 {
1389         int ret = 0;
1390
1391         mutex_lock(&kprobe_mutex);
1392         if (__get_valid_kprobe(p))
1393                 ret = -EINVAL;
1394         mutex_unlock(&kprobe_mutex);
1395
1396         return ret;
1397 }
1398
1399 static int check_kprobe_address_safe(struct kprobe *p,
1400                                      struct module **probed_mod)
1401 {
1402         int ret = 0;
1403         unsigned long ftrace_addr;
1404
1405         /*
1406          * If the address is located on a ftrace nop, set the
1407          * breakpoint to the following instruction.
1408          */
1409         ftrace_addr = ftrace_location((unsigned long)p->addr);
1410         if (ftrace_addr) {
1411 #ifdef CONFIG_KPROBES_ON_FTRACE
1412                 /* Given address is not on the instruction boundary */
1413                 if ((unsigned long)p->addr != ftrace_addr)
1414                         return -EILSEQ;
1415                 p->flags |= KPROBE_FLAG_FTRACE;
1416 #else   /* !CONFIG_KPROBES_ON_FTRACE */
1417                 return -EINVAL;
1418 #endif
1419         }
1420
1421         jump_label_lock();
1422         preempt_disable();
1423
1424         /* Ensure it is not in reserved area nor out of text */
1425         if (!kernel_text_address((unsigned long) p->addr) ||
1426             within_kprobe_blacklist((unsigned long) p->addr) ||
1427             jump_label_text_reserved(p->addr, p->addr)) {
1428                 ret = -EINVAL;
1429                 goto out;
1430         }
1431
1432         /* Check if are we probing a module */
1433         *probed_mod = __module_text_address((unsigned long) p->addr);
1434         if (*probed_mod) {
1435                 /*
1436                  * We must hold a refcount of the probed module while updating
1437                  * its code to prohibit unexpected unloading.
1438                  */
1439                 if (unlikely(!try_module_get(*probed_mod))) {
1440                         ret = -ENOENT;
1441                         goto out;
1442                 }
1443
1444                 /*
1445                  * If the module freed .init.text, we couldn't insert
1446                  * kprobes in there.
1447                  */
1448                 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1449                     (*probed_mod)->state != MODULE_STATE_COMING) {
1450                         module_put(*probed_mod);
1451                         *probed_mod = NULL;
1452                         ret = -ENOENT;
1453                 }
1454         }
1455 out:
1456         preempt_enable();
1457         jump_label_unlock();
1458
1459         return ret;
1460 }
1461
1462 int register_kprobe(struct kprobe *p)
1463 {
1464         int ret;
1465         struct kprobe *old_p;
1466         struct module *probed_mod;
1467         kprobe_opcode_t *addr;
1468
1469         /* Adjust probe address from symbol */
1470         addr = kprobe_addr(p);
1471         if (IS_ERR(addr))
1472                 return PTR_ERR(addr);
1473         p->addr = addr;
1474
1475         ret = check_kprobe_rereg(p);
1476         if (ret)
1477                 return ret;
1478
1479         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1480         p->flags &= KPROBE_FLAG_DISABLED;
1481         p->nmissed = 0;
1482         INIT_LIST_HEAD(&p->list);
1483
1484         ret = check_kprobe_address_safe(p, &probed_mod);
1485         if (ret)
1486                 return ret;
1487
1488         mutex_lock(&kprobe_mutex);
1489
1490         old_p = get_kprobe(p->addr);
1491         if (old_p) {
1492                 /* Since this may unoptimize old_p, locking text_mutex. */
1493                 ret = register_aggr_kprobe(old_p, p);
1494                 goto out;
1495         }
1496
1497         mutex_lock(&text_mutex);        /* Avoiding text modification */
1498         ret = prepare_kprobe(p);
1499         mutex_unlock(&text_mutex);
1500         if (ret)
1501                 goto out;
1502
1503         INIT_HLIST_NODE(&p->hlist);
1504         hlist_add_head_rcu(&p->hlist,
1505                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1506
1507         if (!kprobes_all_disarmed && !kprobe_disabled(p))
1508                 arm_kprobe(p);
1509
1510         /* Try to optimize kprobe */
1511         try_to_optimize_kprobe(p);
1512
1513 out:
1514         mutex_unlock(&kprobe_mutex);
1515
1516         if (probed_mod)
1517                 module_put(probed_mod);
1518
1519         return ret;
1520 }
1521 EXPORT_SYMBOL_GPL(register_kprobe);
1522
1523 /* Check if all probes on the aggrprobe are disabled */
1524 static int aggr_kprobe_disabled(struct kprobe *ap)
1525 {
1526         struct kprobe *kp;
1527
1528         list_for_each_entry_rcu(kp, &ap->list, list)
1529                 if (!kprobe_disabled(kp))
1530                         /*
1531                          * There is an active probe on the list.
1532                          * We can't disable this ap.
1533                          */
1534                         return 0;
1535
1536         return 1;
1537 }
1538
1539 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1540 static struct kprobe *__disable_kprobe(struct kprobe *p)
1541 {
1542         struct kprobe *orig_p;
1543
1544         /* Get an original kprobe for return */
1545         orig_p = __get_valid_kprobe(p);
1546         if (unlikely(orig_p == NULL))
1547                 return NULL;
1548
1549         if (!kprobe_disabled(p)) {
1550                 /* Disable probe if it is a child probe */
1551                 if (p != orig_p)
1552                         p->flags |= KPROBE_FLAG_DISABLED;
1553
1554                 /* Try to disarm and disable this/parent probe */
1555                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1556                         disarm_kprobe(orig_p, true);
1557                         orig_p->flags |= KPROBE_FLAG_DISABLED;
1558                 }
1559         }
1560
1561         return orig_p;
1562 }
1563
1564 /*
1565  * Unregister a kprobe without a scheduler synchronization.
1566  */
1567 static int __unregister_kprobe_top(struct kprobe *p)
1568 {
1569         struct kprobe *ap, *list_p;
1570
1571         /* Disable kprobe. This will disarm it if needed. */
1572         ap = __disable_kprobe(p);
1573         if (ap == NULL)
1574                 return -EINVAL;
1575
1576         if (ap == p)
1577                 /*
1578                  * This probe is an independent(and non-optimized) kprobe
1579                  * (not an aggrprobe). Remove from the hash list.
1580                  */
1581                 goto disarmed;
1582
1583         /* Following process expects this probe is an aggrprobe */
1584         WARN_ON(!kprobe_aggrprobe(ap));
1585
1586         if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1587                 /*
1588                  * !disarmed could be happen if the probe is under delayed
1589                  * unoptimizing.
1590                  */
1591                 goto disarmed;
1592         else {
1593                 /* If disabling probe has special handlers, update aggrprobe */
1594                 if (p->break_handler && !kprobe_gone(p))
1595                         ap->break_handler = NULL;
1596                 if (p->post_handler && !kprobe_gone(p)) {
1597                         list_for_each_entry_rcu(list_p, &ap->list, list) {
1598                                 if ((list_p != p) && (list_p->post_handler))
1599                                         goto noclean;
1600                         }
1601                         ap->post_handler = NULL;
1602                 }
1603 noclean:
1604                 /*
1605                  * Remove from the aggrprobe: this path will do nothing in
1606                  * __unregister_kprobe_bottom().
1607                  */
1608                 list_del_rcu(&p->list);
1609                 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1610                         /*
1611                          * Try to optimize this probe again, because post
1612                          * handler may have been changed.
1613                          */
1614                         optimize_kprobe(ap);
1615         }
1616         return 0;
1617
1618 disarmed:
1619         BUG_ON(!kprobe_disarmed(ap));
1620         hlist_del_rcu(&ap->hlist);
1621         return 0;
1622 }
1623
1624 static void __unregister_kprobe_bottom(struct kprobe *p)
1625 {
1626         struct kprobe *ap;
1627
1628         if (list_empty(&p->list))
1629                 /* This is an independent kprobe */
1630                 arch_remove_kprobe(p);
1631         else if (list_is_singular(&p->list)) {
1632                 /* This is the last child of an aggrprobe */
1633                 ap = list_entry(p->list.next, struct kprobe, list);
1634                 list_del(&p->list);
1635                 free_aggr_kprobe(ap);
1636         }
1637         /* Otherwise, do nothing. */
1638 }
1639
1640 int register_kprobes(struct kprobe **kps, int num)
1641 {
1642         int i, ret = 0;
1643
1644         if (num <= 0)
1645                 return -EINVAL;
1646         for (i = 0; i < num; i++) {
1647                 ret = register_kprobe(kps[i]);
1648                 if (ret < 0) {
1649                         if (i > 0)
1650                                 unregister_kprobes(kps, i);
1651                         break;
1652                 }
1653         }
1654         return ret;
1655 }
1656 EXPORT_SYMBOL_GPL(register_kprobes);
1657
1658 void unregister_kprobe(struct kprobe *p)
1659 {
1660         unregister_kprobes(&p, 1);
1661 }
1662 EXPORT_SYMBOL_GPL(unregister_kprobe);
1663
1664 void unregister_kprobes(struct kprobe **kps, int num)
1665 {
1666         int i;
1667
1668         if (num <= 0)
1669                 return;
1670         mutex_lock(&kprobe_mutex);
1671         for (i = 0; i < num; i++)
1672                 if (__unregister_kprobe_top(kps[i]) < 0)
1673                         kps[i]->addr = NULL;
1674         mutex_unlock(&kprobe_mutex);
1675
1676         synchronize_sched();
1677         for (i = 0; i < num; i++)
1678                 if (kps[i]->addr)
1679                         __unregister_kprobe_bottom(kps[i]);
1680 }
1681 EXPORT_SYMBOL_GPL(unregister_kprobes);
1682
1683 static struct notifier_block kprobe_exceptions_nb = {
1684         .notifier_call = kprobe_exceptions_notify,
1685         .priority = 0x7fffffff /* we need to be notified first */
1686 };
1687
1688 unsigned long __weak arch_deref_entry_point(void *entry)
1689 {
1690         return (unsigned long)entry;
1691 }
1692
1693 int register_jprobes(struct jprobe **jps, int num)
1694 {
1695         struct jprobe *jp;
1696         int ret = 0, i;
1697
1698         if (num <= 0)
1699                 return -EINVAL;
1700         for (i = 0; i < num; i++) {
1701                 unsigned long addr, offset;
1702                 jp = jps[i];
1703                 addr = arch_deref_entry_point(jp->entry);
1704
1705                 /* Verify probepoint is a function entry point */
1706                 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1707                     offset == 0) {
1708                         jp->kp.pre_handler = setjmp_pre_handler;
1709                         jp->kp.break_handler = longjmp_break_handler;
1710                         ret = register_kprobe(&jp->kp);
1711                 } else
1712                         ret = -EINVAL;
1713
1714                 if (ret < 0) {
1715                         if (i > 0)
1716                                 unregister_jprobes(jps, i);
1717                         break;
1718                 }
1719         }
1720         return ret;
1721 }
1722 EXPORT_SYMBOL_GPL(register_jprobes);
1723
1724 int register_jprobe(struct jprobe *jp)
1725 {
1726         return register_jprobes(&jp, 1);
1727 }
1728 EXPORT_SYMBOL_GPL(register_jprobe);
1729
1730 void unregister_jprobe(struct jprobe *jp)
1731 {
1732         unregister_jprobes(&jp, 1);
1733 }
1734 EXPORT_SYMBOL_GPL(unregister_jprobe);
1735
1736 void unregister_jprobes(struct jprobe **jps, int num)
1737 {
1738         int i;
1739
1740         if (num <= 0)
1741                 return;
1742         mutex_lock(&kprobe_mutex);
1743         for (i = 0; i < num; i++)
1744                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1745                         jps[i]->kp.addr = NULL;
1746         mutex_unlock(&kprobe_mutex);
1747
1748         synchronize_sched();
1749         for (i = 0; i < num; i++) {
1750                 if (jps[i]->kp.addr)
1751                         __unregister_kprobe_bottom(&jps[i]->kp);
1752         }
1753 }
1754 EXPORT_SYMBOL_GPL(unregister_jprobes);
1755
1756 #ifdef CONFIG_KRETPROBES
1757 /*
1758  * This kprobe pre_handler is registered with every kretprobe. When probe
1759  * hits it will set up the return probe.
1760  */
1761 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1762                                            struct pt_regs *regs)
1763 {
1764         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1765         unsigned long hash, flags = 0;
1766         struct kretprobe_instance *ri;
1767
1768         /*TODO: consider to only swap the RA after the last pre_handler fired */
1769         hash = hash_ptr(current, KPROBE_HASH_BITS);
1770         raw_spin_lock_irqsave(&rp->lock, flags);
1771         if (!hlist_empty(&rp->free_instances)) {
1772                 ri = hlist_entry(rp->free_instances.first,
1773                                 struct kretprobe_instance, hlist);
1774                 hlist_del(&ri->hlist);
1775                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1776
1777                 ri->rp = rp;
1778                 ri->task = current;
1779
1780                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1781                         raw_spin_lock_irqsave(&rp->lock, flags);
1782                         hlist_add_head(&ri->hlist, &rp->free_instances);
1783                         raw_spin_unlock_irqrestore(&rp->lock, flags);
1784                         return 0;
1785                 }
1786
1787                 arch_prepare_kretprobe(ri, regs);
1788
1789                 /* XXX(hch): why is there no hlist_move_head? */
1790                 INIT_HLIST_NODE(&ri->hlist);
1791                 kretprobe_table_lock(hash, &flags);
1792                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1793                 kretprobe_table_unlock(hash, &flags);
1794         } else {
1795                 rp->nmissed++;
1796                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1797         }
1798         return 0;
1799 }
1800
1801 int register_kretprobe(struct kretprobe *rp)
1802 {
1803         int ret = 0;
1804         struct kretprobe_instance *inst;
1805         int i;
1806         void *addr;
1807
1808         if (kretprobe_blacklist_size) {
1809                 addr = kprobe_addr(&rp->kp);
1810                 if (IS_ERR(addr))
1811                         return PTR_ERR(addr);
1812
1813                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1814                         if (kretprobe_blacklist[i].addr == addr)
1815                                 return -EINVAL;
1816                 }
1817         }
1818
1819         rp->kp.pre_handler = pre_handler_kretprobe;
1820         rp->kp.post_handler = NULL;
1821         rp->kp.fault_handler = NULL;
1822         rp->kp.break_handler = NULL;
1823
1824         /* Pre-allocate memory for max kretprobe instances */
1825         if (rp->maxactive <= 0) {
1826 #ifdef CONFIG_PREEMPT
1827                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1828 #else
1829                 rp->maxactive = num_possible_cpus();
1830 #endif
1831         }
1832         raw_spin_lock_init(&rp->lock);
1833         INIT_HLIST_HEAD(&rp->free_instances);
1834         for (i = 0; i < rp->maxactive; i++) {
1835                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1836                                rp->data_size, GFP_KERNEL);
1837                 if (inst == NULL) {
1838                         free_rp_inst(rp);
1839                         return -ENOMEM;
1840                 }
1841                 INIT_HLIST_NODE(&inst->hlist);
1842                 hlist_add_head(&inst->hlist, &rp->free_instances);
1843         }
1844
1845         rp->nmissed = 0;
1846         /* Establish function entry probe point */
1847         ret = register_kprobe(&rp->kp);
1848         if (ret != 0)
1849                 free_rp_inst(rp);
1850         return ret;
1851 }
1852 EXPORT_SYMBOL_GPL(register_kretprobe);
1853
1854 int register_kretprobes(struct kretprobe **rps, int num)
1855 {
1856         int ret = 0, i;
1857
1858         if (num <= 0)
1859                 return -EINVAL;
1860         for (i = 0; i < num; i++) {
1861                 ret = register_kretprobe(rps[i]);
1862                 if (ret < 0) {
1863                         if (i > 0)
1864                                 unregister_kretprobes(rps, i);
1865                         break;
1866                 }
1867         }
1868         return ret;
1869 }
1870 EXPORT_SYMBOL_GPL(register_kretprobes);
1871
1872 void unregister_kretprobe(struct kretprobe *rp)
1873 {
1874         unregister_kretprobes(&rp, 1);
1875 }
1876 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1877
1878 void unregister_kretprobes(struct kretprobe **rps, int num)
1879 {
1880         int i;
1881
1882         if (num <= 0)
1883                 return;
1884         mutex_lock(&kprobe_mutex);
1885         for (i = 0; i < num; i++)
1886                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1887                         rps[i]->kp.addr = NULL;
1888         mutex_unlock(&kprobe_mutex);
1889
1890         synchronize_sched();
1891         for (i = 0; i < num; i++) {
1892                 if (rps[i]->kp.addr) {
1893                         __unregister_kprobe_bottom(&rps[i]->kp);
1894                         cleanup_rp_inst(rps[i]);
1895                 }
1896         }
1897 }
1898 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1899
1900 #else /* CONFIG_KRETPROBES */
1901 int register_kretprobe(struct kretprobe *rp)
1902 {
1903         return -ENOSYS;
1904 }
1905 EXPORT_SYMBOL_GPL(register_kretprobe);
1906
1907 int register_kretprobes(struct kretprobe **rps, int num)
1908 {
1909         return -ENOSYS;
1910 }
1911 EXPORT_SYMBOL_GPL(register_kretprobes);
1912
1913 void unregister_kretprobe(struct kretprobe *rp)
1914 {
1915 }
1916 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1917
1918 void unregister_kretprobes(struct kretprobe **rps, int num)
1919 {
1920 }
1921 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1922
1923 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1924                                            struct pt_regs *regs)
1925 {
1926         return 0;
1927 }
1928
1929 #endif /* CONFIG_KRETPROBES */
1930
1931 /* Set the kprobe gone and remove its instruction buffer. */
1932 static void kill_kprobe(struct kprobe *p)
1933 {
1934         struct kprobe *kp;
1935
1936         p->flags |= KPROBE_FLAG_GONE;
1937         if (kprobe_aggrprobe(p)) {
1938                 /*
1939                  * If this is an aggr_kprobe, we have to list all the
1940                  * chained probes and mark them GONE.
1941                  */
1942                 list_for_each_entry_rcu(kp, &p->list, list)
1943                         kp->flags |= KPROBE_FLAG_GONE;
1944                 p->post_handler = NULL;
1945                 p->break_handler = NULL;
1946                 kill_optimized_kprobe(p);
1947         }
1948         /*
1949          * Here, we can remove insn_slot safely, because no thread calls
1950          * the original probed function (which will be freed soon) any more.
1951          */
1952         arch_remove_kprobe(p);
1953 }
1954
1955 /* Disable one kprobe */
1956 int disable_kprobe(struct kprobe *kp)
1957 {
1958         int ret = 0;
1959
1960         mutex_lock(&kprobe_mutex);
1961
1962         /* Disable this kprobe */
1963         if (__disable_kprobe(kp) == NULL)
1964                 ret = -EINVAL;
1965
1966         mutex_unlock(&kprobe_mutex);
1967         return ret;
1968 }
1969 EXPORT_SYMBOL_GPL(disable_kprobe);
1970
1971 /* Enable one kprobe */
1972 int enable_kprobe(struct kprobe *kp)
1973 {
1974         int ret = 0;
1975         struct kprobe *p;
1976
1977         mutex_lock(&kprobe_mutex);
1978
1979         /* Check whether specified probe is valid. */
1980         p = __get_valid_kprobe(kp);
1981         if (unlikely(p == NULL)) {
1982                 ret = -EINVAL;
1983                 goto out;
1984         }
1985
1986         if (kprobe_gone(kp)) {
1987                 /* This kprobe has gone, we couldn't enable it. */
1988                 ret = -EINVAL;
1989                 goto out;
1990         }
1991
1992         if (p != kp)
1993                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1994
1995         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
1996                 p->flags &= ~KPROBE_FLAG_DISABLED;
1997                 arm_kprobe(p);
1998         }
1999 out:
2000         mutex_unlock(&kprobe_mutex);
2001         return ret;
2002 }
2003 EXPORT_SYMBOL_GPL(enable_kprobe);
2004
2005 void __kprobes dump_kprobe(struct kprobe *kp)
2006 {
2007         printk(KERN_WARNING "Dumping kprobe:\n");
2008         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2009                kp->symbol_name, kp->addr, kp->offset);
2010 }
2011
2012 /*
2013  * Lookup and populate the kprobe_blacklist.
2014  *
2015  * Unlike the kretprobe blacklist, we'll need to determine
2016  * the range of addresses that belong to the said functions,
2017  * since a kprobe need not necessarily be at the beginning
2018  * of a function.
2019  */
2020 static int __init populate_kprobe_blacklist(unsigned long *start,
2021                                              unsigned long *end)
2022 {
2023         unsigned long *iter;
2024         struct kprobe_blacklist_entry *ent;
2025         unsigned long offset = 0, size = 0;
2026
2027         for (iter = start; iter < end; iter++) {
2028                 if (!kallsyms_lookup_size_offset(*iter, &size, &offset)) {
2029                         pr_err("Failed to find blacklist %p\n", (void *)*iter);
2030                         continue;
2031                 }
2032
2033                 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2034                 if (!ent)
2035                         return -ENOMEM;
2036                 ent->start_addr = *iter;
2037                 ent->end_addr = *iter + size;
2038                 INIT_LIST_HEAD(&ent->list);
2039                 list_add_tail(&ent->list, &kprobe_blacklist);
2040         }
2041         return 0;
2042 }
2043
2044 /* Module notifier call back, checking kprobes on the module */
2045 static int kprobes_module_callback(struct notifier_block *nb,
2046                                    unsigned long val, void *data)
2047 {
2048         struct module *mod = data;
2049         struct hlist_head *head;
2050         struct kprobe *p;
2051         unsigned int i;
2052         int checkcore = (val == MODULE_STATE_GOING);
2053
2054         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2055                 return NOTIFY_DONE;
2056
2057         /*
2058          * When MODULE_STATE_GOING was notified, both of module .text and
2059          * .init.text sections would be freed. When MODULE_STATE_LIVE was
2060          * notified, only .init.text section would be freed. We need to
2061          * disable kprobes which have been inserted in the sections.
2062          */
2063         mutex_lock(&kprobe_mutex);
2064         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2065                 head = &kprobe_table[i];
2066                 hlist_for_each_entry_rcu(p, head, hlist)
2067                         if (within_module_init((unsigned long)p->addr, mod) ||
2068                             (checkcore &&
2069                              within_module_core((unsigned long)p->addr, mod))) {
2070                                 /*
2071                                  * The vaddr this probe is installed will soon
2072                                  * be vfreed buy not synced to disk. Hence,
2073                                  * disarming the breakpoint isn't needed.
2074                                  */
2075                                 kill_kprobe(p);
2076                         }
2077         }
2078         mutex_unlock(&kprobe_mutex);
2079         return NOTIFY_DONE;
2080 }
2081
2082 static struct notifier_block kprobe_module_nb = {
2083         .notifier_call = kprobes_module_callback,
2084         .priority = 0
2085 };
2086
2087 /* Markers of _kprobe_blacklist section */
2088 extern unsigned long __start_kprobe_blacklist[];
2089 extern unsigned long __stop_kprobe_blacklist[];
2090
2091 static int __init init_kprobes(void)
2092 {
2093         int i, err = 0;
2094
2095         /* FIXME allocate the probe table, currently defined statically */
2096         /* initialize all list heads */
2097         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2098                 INIT_HLIST_HEAD(&kprobe_table[i]);
2099                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2100                 raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2101         }
2102
2103         err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2104                                         __stop_kprobe_blacklist);
2105         if (err) {
2106                 pr_err("kprobes: failed to populate blacklist: %d\n", err);
2107                 pr_err("Please take care of using kprobes.\n");
2108         }
2109
2110         if (kretprobe_blacklist_size) {
2111                 /* lookup the function address from its name */
2112                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2113                         kprobe_lookup_name(kretprobe_blacklist[i].name,
2114                                            kretprobe_blacklist[i].addr);
2115                         if (!kretprobe_blacklist[i].addr)
2116                                 printk("kretprobe: lookup failed: %s\n",
2117                                        kretprobe_blacklist[i].name);
2118                 }
2119         }
2120
2121 #if defined(CONFIG_OPTPROBES)
2122 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2123         /* Init kprobe_optinsn_slots */
2124         kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2125 #endif
2126         /* By default, kprobes can be optimized */
2127         kprobes_allow_optimization = true;
2128 #endif
2129
2130         /* By default, kprobes are armed */
2131         kprobes_all_disarmed = false;
2132
2133         err = arch_init_kprobes();
2134         if (!err)
2135                 err = register_die_notifier(&kprobe_exceptions_nb);
2136         if (!err)
2137                 err = register_module_notifier(&kprobe_module_nb);
2138
2139         kprobes_initialized = (err == 0);
2140
2141         if (!err)
2142                 init_test_probes();
2143         return err;
2144 }
2145
2146 #ifdef CONFIG_DEBUG_FS
2147 static void report_probe(struct seq_file *pi, struct kprobe *p,
2148                 const char *sym, int offset, char *modname, struct kprobe *pp)
2149 {
2150         char *kprobe_type;
2151
2152         if (p->pre_handler == pre_handler_kretprobe)
2153                 kprobe_type = "r";
2154         else if (p->pre_handler == setjmp_pre_handler)
2155                 kprobe_type = "j";
2156         else
2157                 kprobe_type = "k";
2158
2159         if (sym)
2160                 seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2161                         p->addr, kprobe_type, sym, offset,
2162                         (modname ? modname : " "));
2163         else
2164                 seq_printf(pi, "%p  %s  %p ",
2165                         p->addr, kprobe_type, p->addr);
2166
2167         if (!pp)
2168                 pp = p;
2169         seq_printf(pi, "%s%s%s%s\n",
2170                 (kprobe_gone(p) ? "[GONE]" : ""),
2171                 ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2172                 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2173                 (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2174 }
2175
2176 static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2177 {
2178         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2179 }
2180
2181 static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2182 {
2183         (*pos)++;
2184         if (*pos >= KPROBE_TABLE_SIZE)
2185                 return NULL;
2186         return pos;
2187 }
2188
2189 static void kprobe_seq_stop(struct seq_file *f, void *v)
2190 {
2191         /* Nothing to do */
2192 }
2193
2194 static int show_kprobe_addr(struct seq_file *pi, void *v)
2195 {
2196         struct hlist_head *head;
2197         struct kprobe *p, *kp;
2198         const char *sym = NULL;
2199         unsigned int i = *(loff_t *) v;
2200         unsigned long offset = 0;
2201         char *modname, namebuf[KSYM_NAME_LEN];
2202
2203         head = &kprobe_table[i];
2204         preempt_disable();
2205         hlist_for_each_entry_rcu(p, head, hlist) {
2206                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2207                                         &offset, &modname, namebuf);
2208                 if (kprobe_aggrprobe(p)) {
2209                         list_for_each_entry_rcu(kp, &p->list, list)
2210                                 report_probe(pi, kp, sym, offset, modname, p);
2211                 } else
2212                         report_probe(pi, p, sym, offset, modname, NULL);
2213         }
2214         preempt_enable();
2215         return 0;
2216 }
2217
2218 static const struct seq_operations kprobes_seq_ops = {
2219         .start = kprobe_seq_start,
2220         .next  = kprobe_seq_next,
2221         .stop  = kprobe_seq_stop,
2222         .show  = show_kprobe_addr
2223 };
2224
2225 static int kprobes_open(struct inode *inode, struct file *filp)
2226 {
2227         return seq_open(filp, &kprobes_seq_ops);
2228 }
2229
2230 static const struct file_operations debugfs_kprobes_operations = {
2231         .open           = kprobes_open,
2232         .read           = seq_read,
2233         .llseek         = seq_lseek,
2234         .release        = seq_release,
2235 };
2236
2237 static void arm_all_kprobes(void)
2238 {
2239         struct hlist_head *head;
2240         struct kprobe *p;
2241         unsigned int i;
2242
2243         mutex_lock(&kprobe_mutex);
2244
2245         /* If kprobes are armed, just return */
2246         if (!kprobes_all_disarmed)
2247                 goto already_enabled;
2248
2249         /* Arming kprobes doesn't optimize kprobe itself */
2250         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2251                 head = &kprobe_table[i];
2252                 hlist_for_each_entry_rcu(p, head, hlist)
2253                         if (!kprobe_disabled(p))
2254                                 arm_kprobe(p);
2255         }
2256
2257         kprobes_all_disarmed = false;
2258         printk(KERN_INFO "Kprobes globally enabled\n");
2259
2260 already_enabled:
2261         mutex_unlock(&kprobe_mutex);
2262         return;
2263 }
2264
2265 static void disarm_all_kprobes(void)
2266 {
2267         struct hlist_head *head;
2268         struct kprobe *p;
2269         unsigned int i;
2270
2271         mutex_lock(&kprobe_mutex);
2272
2273         /* If kprobes are already disarmed, just return */
2274         if (kprobes_all_disarmed) {
2275                 mutex_unlock(&kprobe_mutex);
2276                 return;
2277         }
2278
2279         kprobes_all_disarmed = true;
2280         printk(KERN_INFO "Kprobes globally disabled\n");
2281
2282         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2283                 head = &kprobe_table[i];
2284                 hlist_for_each_entry_rcu(p, head, hlist) {
2285                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2286                                 disarm_kprobe(p, false);
2287                 }
2288         }
2289         mutex_unlock(&kprobe_mutex);
2290
2291         /* Wait for disarming all kprobes by optimizer */
2292         wait_for_kprobe_optimizer();
2293 }
2294
2295 /*
2296  * XXX: The debugfs bool file interface doesn't allow for callbacks
2297  * when the bool state is switched. We can reuse that facility when
2298  * available
2299  */
2300 static ssize_t read_enabled_file_bool(struct file *file,
2301                char __user *user_buf, size_t count, loff_t *ppos)
2302 {
2303         char buf[3];
2304
2305         if (!kprobes_all_disarmed)
2306                 buf[0] = '1';
2307         else
2308                 buf[0] = '0';
2309         buf[1] = '\n';
2310         buf[2] = 0x00;
2311         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2312 }
2313
2314 static ssize_t write_enabled_file_bool(struct file *file,
2315                const char __user *user_buf, size_t count, loff_t *ppos)
2316 {
2317         char buf[32];
2318         size_t buf_size;
2319
2320         buf_size = min(count, (sizeof(buf)-1));
2321         if (copy_from_user(buf, user_buf, buf_size))
2322                 return -EFAULT;
2323
2324         buf[buf_size] = '\0';
2325         switch (buf[0]) {
2326         case 'y':
2327         case 'Y':
2328         case '1':
2329                 arm_all_kprobes();
2330                 break;
2331         case 'n':
2332         case 'N':
2333         case '0':
2334                 disarm_all_kprobes();
2335                 break;
2336         default:
2337                 return -EINVAL;
2338         }
2339
2340         return count;
2341 }
2342
2343 static const struct file_operations fops_kp = {
2344         .read =         read_enabled_file_bool,
2345         .write =        write_enabled_file_bool,
2346         .llseek =       default_llseek,
2347 };
2348
2349 static int __init debugfs_kprobe_init(void)
2350 {
2351         struct dentry *dir, *file;
2352         unsigned int value = 1;
2353
2354         dir = debugfs_create_dir("kprobes", NULL);
2355         if (!dir)
2356                 return -ENOMEM;
2357
2358         file = debugfs_create_file("list", 0444, dir, NULL,
2359                                 &debugfs_kprobes_operations);
2360         if (!file) {
2361                 debugfs_remove(dir);
2362                 return -ENOMEM;
2363         }
2364
2365         file = debugfs_create_file("enabled", 0600, dir,
2366                                         &value, &fops_kp);
2367         if (!file) {
2368                 debugfs_remove(dir);
2369                 return -ENOMEM;
2370         }
2371
2372         return 0;
2373 }
2374
2375 late_initcall(debugfs_kprobe_init);
2376 #endif /* CONFIG_DEBUG_FS */
2377
2378 module_init(init_kprobes);
2379
2380 /* defined in arch/.../kernel/kprobes.c */
2381 EXPORT_SYMBOL_GPL(jprobe_return);