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