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/kdebug.h>
  46 #include <linux/memory.h>
  47
  48 #include <asm-generic/sections.h>
  49 #include <asm/cacheflush.h>
  50 #include <asm/errno.h>
  51 #include <asm/uaccess.h>
  52
  53 #define KPROBE_HASH_BITS 6
  54 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
  55
  56
  57 /*
  58  * Some oddball architectures like 64bit powerpc have function descriptors
  59  * so this must be overridable.
  60  */
  61 #ifndef kprobe_lookup_name
  62 #define kprobe_lookup_name(name, addr) \
  63         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
  64 #endif
  65
  66 static int kprobes_initialized;
  67 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  68 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
  69
  70 /* NOTE: change this value only with kprobe_mutex held */
  71 static bool kprobes_all_disarmed;
  72
  73 static DEFINE_MUTEX(kprobe_mutex);      /* Protects kprobe_table */
  74 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
  75 static struct {
  76         spinlock_t lock ____cacheline_aligned_in_smp;
  77 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
  78
  79 static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
  80 {
  81         return &(kretprobe_table_locks[hash].lock);
  82 }
  83
  84 /*
  85  * Normally, functions that we'd want to prohibit kprobes in, are marked
  86  * __kprobes. But, there are cases where such functions already belong to
  87  * a different section (__sched for preempt_schedule)
  88  *
  89  * For such cases, we now have a blacklist
  90  */
  91 static struct kprobe_blackpoint kprobe_blacklist[] = {
  92         {"preempt_schedule",},
  93         {NULL}    /* Terminator */
  94 };
  95
  96 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
  97 /*
  98  * kprobe->ainsn.insn points to the copy of the instruction to be
  99  * single-stepped. x86_64, POWER4 and above have no-exec support and
 100  * stepping on the instruction on a vmalloced/kmalloced/data page
 101  * is a recipe for disaster
 102  */
 103 #define INSNS_PER_PAGE  (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
 104
 105 struct kprobe_insn_page {
 106         struct list_head list;
 107         kprobe_opcode_t *insns;         /* Page of instruction slots */
 108         char slot_used[INSNS_PER_PAGE];
 109         int nused;
 110         int ngarbage;
 111 };
 112
 113 enum kprobe_slot_state {
 114         SLOT_CLEAN = 0,
 115         SLOT_DIRTY = 1,
 116         SLOT_USED = 2,
 117 };
 118
 119 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */
 120 static LIST_HEAD(kprobe_insn_pages);
 121 static int kprobe_garbage_slots;
 122 static int collect_garbage_slots(void);
 123
 124 static int __kprobes check_safety(void)
 125 {
 126         int ret = 0;
 127 #if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
 128         ret = freeze_processes();
 129         if (ret == 0) {
 130                 struct task_struct *p, *q;
 131                 do_each_thread(p, q) {
 132                         if (p != current && p->state == TASK_RUNNING &&
 133                             p->pid != 0) {
 134                                 printk("Check failed: %s is running\n",p->comm);
 135                                 ret = -1;
 136                                 goto loop_end;
 137                         }
 138                 } while_each_thread(p, q);
 139         }
 140 loop_end:
 141         thaw_processes();
 142 #else
 143         synchronize_sched();
 144 #endif
 145         return ret;
 146 }
 147
 148 /**
 149  * __get_insn_slot() - Find a slot on an executable page for an instruction.
 150  * We allocate an executable page if there's no room on existing ones.
 151  */
 152 static kprobe_opcode_t __kprobes *__get_insn_slot(void)
 153 {
 154         struct kprobe_insn_page *kip;
 155
 156  retry:
 157         list_for_each_entry(kip, &kprobe_insn_pages, list) {
 158                 if (kip->nused < INSNS_PER_PAGE) {
 159                         int i;
 160                         for (i = 0; i < INSNS_PER_PAGE; i++) {
 161                                 if (kip->slot_used[i] == SLOT_CLEAN) {
 162                                         kip->slot_used[i] = SLOT_USED;
 163                                         kip->nused++;
 164                                         return kip->insns + (i * MAX_INSN_SIZE);
 165                                 }
 166                         }
 167                         /* Surprise!  No unused slots.  Fix kip->nused. */
 168                         kip->nused = INSNS_PER_PAGE;
 169                 }
 170         }
 171
 172         /* If there are any garbage slots, collect it and try again. */
 173         if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
 174                 goto retry;
 175         }
 176         /* All out of space.  Need to allocate a new page. Use slot 0. */
 177         kip = kmalloc(sizeof(struct kprobe_insn_page), 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         list_add(&kip->list, &kprobe_insn_pages);
 193         memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
 194         kip->slot_used[0] = SLOT_USED;
 195         kip->nused = 1;
 196         kip->ngarbage = 0;
 197         return kip->insns;
 198 }
 199
 200 kprobe_opcode_t __kprobes *get_insn_slot(void)
 201 {
 202         kprobe_opcode_t *ret;
 203         mutex_lock(&kprobe_insn_mutex);
 204         ret = __get_insn_slot();
 205         mutex_unlock(&kprobe_insn_mutex);
 206         return ret;
 207 }
 208
 209 /* Return 1 if all garbages are collected, otherwise 0. */
 210 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
 211 {
 212         kip->slot_used[idx] = SLOT_CLEAN;
 213         kip->nused--;
 214         if (kip->nused == 0) {
 215                 /*
 216                  * Page is no longer in use.  Free it unless
 217                  * it's the last one.  We keep the last one
 218                  * so as not to have to set it up again the
 219                  * next time somebody inserts a probe.
 220                  */
 221                 if (!list_is_singular(&kprobe_insn_pages)) {
 222                         list_del(&kip->list);
 223                         module_free(NULL, kip->insns);
 224                         kfree(kip);
 225                 }
 226                 return 1;
 227         }
 228         return 0;
 229 }
 230
 231 static int __kprobes collect_garbage_slots(void)
 232 {
 233         struct kprobe_insn_page *kip, *next;
 234
 235         /* Ensure no-one is preepmted on the garbages */
 236         if (check_safety())
 237                 return -EAGAIN;
 238
 239         list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
 240                 int i;
 241                 if (kip->ngarbage == 0)
 242                         continue;
 243                 kip->ngarbage = 0;      /* we will collect all garbages */
 244                 for (i = 0; i < INSNS_PER_PAGE; i++) {
 245                         if (kip->slot_used[i] == SLOT_DIRTY &&
 246                             collect_one_slot(kip, i))
 247                                 break;
 248                 }
 249         }
 250         kprobe_garbage_slots = 0;
 251         return 0;
 252 }
 253
 254 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
 255 {
 256         struct kprobe_insn_page *kip;
 257
 258         mutex_lock(&kprobe_insn_mutex);
 259         list_for_each_entry(kip, &kprobe_insn_pages, list) {
 260                 if (kip->insns <= slot &&
 261                     slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
 262                         int i = (slot - kip->insns) / MAX_INSN_SIZE;
 263                         if (dirty) {
 264                                 kip->slot_used[i] = SLOT_DIRTY;
 265                                 kip->ngarbage++;
 266                         } else
 267                                 collect_one_slot(kip, i);
 268                         break;
 269                 }
 270         }
 271
 272         if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
 273                 collect_garbage_slots();
 274
 275         mutex_unlock(&kprobe_insn_mutex);
 276 }
 277 #endif
 278
 279 /* We have preemption disabled.. so it is safe to use __ versions */
 280 static inline void set_kprobe_instance(struct kprobe *kp)
 281 {
 282         __get_cpu_var(kprobe_instance) = kp;
 283 }
 284
 285 static inline void reset_kprobe_instance(void)
 286 {
 287         __get_cpu_var(kprobe_instance) = NULL;
 288 }
 289
 290 /*
 291  * This routine is called either:
 292  *      - under the kprobe_mutex - during kprobe_[un]register()
 293  *                              OR
 294  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
 295  */
 296 struct kprobe __kprobes *get_kprobe(void *addr)
 297 {
 298         struct hlist_head *head;
 299         struct hlist_node *node;
 300         struct kprobe *p;
 301
 302         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
 303         hlist_for_each_entry_rcu(p, node, head, hlist) {
 304                 if (p->addr == addr)
 305                         return p;
 306         }
 307         return NULL;
 308 }
 309
 310 /* Arm a kprobe with text_mutex */
 311 static void __kprobes arm_kprobe(struct kprobe *kp)
 312 {
 313         mutex_lock(&text_mutex);
 314         arch_arm_kprobe(kp);
 315         mutex_unlock(&text_mutex);
 316 }
 317
 318 /* Disarm a kprobe with text_mutex */
 319 static void __kprobes disarm_kprobe(struct kprobe *kp)
 320 {
 321         mutex_lock(&text_mutex);
 322         arch_disarm_kprobe(kp);
 323         mutex_unlock(&text_mutex);
 324 }
 325
 326 /*
 327  * Aggregate handlers for multiple kprobes support - these handlers
 328  * take care of invoking the individual kprobe handlers on p->list
 329  */
 330 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
 331 {
 332         struct kprobe *kp;
 333
 334         list_for_each_entry_rcu(kp, &p->list, list) {
 335                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 336                         set_kprobe_instance(kp);
 337                         if (kp->pre_handler(kp, regs))
 338                                 return 1;
 339                 }
 340                 reset_kprobe_instance();
 341         }
 342         return 0;
 343 }
 344
 345 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
 346                                         unsigned long flags)
 347 {
 348         struct kprobe *kp;
 349
 350         list_for_each_entry_rcu(kp, &p->list, list) {
 351                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
 352                         set_kprobe_instance(kp);
 353                         kp->post_handler(kp, regs, flags);
 354                         reset_kprobe_instance();
 355                 }
 356         }
 357 }
 358
 359 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
 360                                         int trapnr)
 361 {
 362         struct kprobe *cur = __get_cpu_var(kprobe_instance);
 363
 364         /*
 365          * if we faulted "during" the execution of a user specified
 366          * probe handler, invoke just that probe's fault handler
 367          */
 368         if (cur && cur->fault_handler) {
 369                 if (cur->fault_handler(cur, regs, trapnr))
 370                         return 1;
 371         }
 372         return 0;
 373 }
 374
 375 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
 376 {
 377         struct kprobe *cur = __get_cpu_var(kprobe_instance);
 378         int ret = 0;
 379
 380         if (cur && cur->break_handler) {
 381                 if (cur->break_handler(cur, regs))
 382                         ret = 1;
 383         }
 384         reset_kprobe_instance();
 385         return ret;
 386 }
 387
 388 /* Walks the list and increments nmissed count for multiprobe case */
 389 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
 390 {
 391         struct kprobe *kp;
 392         if (p->pre_handler != aggr_pre_handler) {
 393                 p->nmissed++;
 394         } else {
 395                 list_for_each_entry_rcu(kp, &p->list, list)
 396                         kp->nmissed++;
 397         }
 398         return;
 399 }
 400
 401 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
 402                                 struct hlist_head *head)
 403 {
 404         struct kretprobe *rp = ri->rp;
 405
 406         /* remove rp inst off the rprobe_inst_table */
 407         hlist_del(&ri->hlist);
 408         INIT_HLIST_NODE(&ri->hlist);
 409         if (likely(rp)) {
 410                 spin_lock(&rp->lock);
 411                 hlist_add_head(&ri->hlist, &rp->free_instances);
 412                 spin_unlock(&rp->lock);
 413         } else
 414                 /* Unregistering */
 415                 hlist_add_head(&ri->hlist, head);
 416 }
 417
 418 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
 419                          struct hlist_head **head, unsigned long *flags)
 420 {
 421         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
 422         spinlock_t *hlist_lock;
 423
 424         *head = &kretprobe_inst_table[hash];
 425         hlist_lock = kretprobe_table_lock_ptr(hash);
 426         spin_lock_irqsave(hlist_lock, *flags);
 427 }
 428
 429 static void __kprobes kretprobe_table_lock(unsigned long hash,
 430         unsigned long *flags)
 431 {
 432         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
 433         spin_lock_irqsave(hlist_lock, *flags);
 434 }
 435
 436 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
 437         unsigned long *flags)
 438 {
 439         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
 440         spinlock_t *hlist_lock;
 441
 442         hlist_lock = kretprobe_table_lock_ptr(hash);
 443         spin_unlock_irqrestore(hlist_lock, *flags);
 444 }
 445
 446 void __kprobes kretprobe_table_unlock(unsigned long hash, unsigned long *flags)
 447 {
 448         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
 449         spin_unlock_irqrestore(hlist_lock, *flags);
 450 }
 451
 452 /*
 453  * This function is called from finish_task_switch when task tk becomes dead,
 454  * so that we can recycle any function-return probe instances associated
 455  * with this task. These left over instances represent probed functions
 456  * that have been called but will never return.
 457  */
 458 void __kprobes kprobe_flush_task(struct task_struct *tk)
 459 {
 460         struct kretprobe_instance *ri;
 461         struct hlist_head *head, empty_rp;
 462         struct hlist_node *node, *tmp;
 463         unsigned long hash, flags = 0;
 464
 465         if (unlikely(!kprobes_initialized))
 466                 /* Early boot.  kretprobe_table_locks not yet initialized. */
 467                 return;
 468
 469         hash = hash_ptr(tk, KPROBE_HASH_BITS);
 470         head = &kretprobe_inst_table[hash];
 471         kretprobe_table_lock(hash, &flags);
 472         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 473                 if (ri->task == tk)
 474                         recycle_rp_inst(ri, &empty_rp);
 475         }
 476         kretprobe_table_unlock(hash, &flags);
 477         INIT_HLIST_HEAD(&empty_rp);
 478         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 479                 hlist_del(&ri->hlist);
 480                 kfree(ri);
 481         }
 482 }
 483
 484 static inline void free_rp_inst(struct kretprobe *rp)
 485 {
 486         struct kretprobe_instance *ri;
 487         struct hlist_node *pos, *next;
 488
 489         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
 490                 hlist_del(&ri->hlist);
 491                 kfree(ri);
 492         }
 493 }
 494
 495 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
 496 {
 497         unsigned long flags, hash;
 498         struct kretprobe_instance *ri;
 499         struct hlist_node *pos, *next;
 500         struct hlist_head *head;
 501
 502         /* No race here */
 503         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
 504                 kretprobe_table_lock(hash, &flags);
 505                 head = &kretprobe_inst_table[hash];
 506                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
 507                         if (ri->rp == rp)
 508                                 ri->rp = NULL;
 509                 }
 510                 kretprobe_table_unlock(hash, &flags);
 511         }
 512         free_rp_inst(rp);
 513 }
 514
 515 /*
 516  * Keep all fields in the kprobe consistent
 517  */
 518 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
 519 {
 520         memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
 521         memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
 522 }
 523
 524 /*
 525 * Add the new probe to ap->list. Fail if this is the
 526 * second jprobe at the address - two jprobes can't coexist
 527 */
 528 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
 529 {
 530         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
 531         if (p->break_handler) {
 532                 if (ap->break_handler)
 533                         return -EEXIST;
 534                 list_add_tail_rcu(&p->list, &ap->list);
 535                 ap->break_handler = aggr_break_handler;
 536         } else
 537                 list_add_rcu(&p->list, &ap->list);
 538         if (p->post_handler && !ap->post_handler)
 539                 ap->post_handler = aggr_post_handler;
 540
 541         if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
 542                 ap->flags &= ~KPROBE_FLAG_DISABLED;
 543                 if (!kprobes_all_disarmed)
 544                         /* Arm the breakpoint again. */
 545                         arm_kprobe(ap);
 546         }
 547         return 0;
 548 }
 549
 550 /*
 551  * Fill in the required fields of the "manager kprobe". Replace the
 552  * earlier kprobe in the hlist with the manager kprobe
 553  */
 554 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 555 {
 556         copy_kprobe(p, ap);
 557         flush_insn_slot(ap);
 558         ap->addr = p->addr;
 559         ap->flags = p->flags;
 560         ap->pre_handler = aggr_pre_handler;
 561         ap->fault_handler = aggr_fault_handler;
 562         /* We don't care the kprobe which has gone. */
 563         if (p->post_handler && !kprobe_gone(p))
 564                 ap->post_handler = aggr_post_handler;
 565         if (p->break_handler && !kprobe_gone(p))
 566                 ap->break_handler = aggr_break_handler;
 567
 568         INIT_LIST_HEAD(&ap->list);
 569         list_add_rcu(&p->list, &ap->list);
 570
 571         hlist_replace_rcu(&p->hlist, &ap->hlist);
 572 }
 573
 574 /*
 575  * This is the second or subsequent kprobe at the address - handle
 576  * the intricacies
 577  */
 578 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
 579                                           struct kprobe *p)
 580 {
 581         int ret = 0;
 582         struct kprobe *ap = old_p;
 583
 584         if (old_p->pre_handler != aggr_pre_handler) {
 585                 /* If old_p is not an aggr_probe, create new aggr_kprobe. */
 586                 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
 587                 if (!ap)
 588                         return -ENOMEM;
 589                 add_aggr_kprobe(ap, old_p);
 590         }
 591
 592         if (kprobe_gone(ap)) {
 593                 /*
 594                  * Attempting to insert new probe at the same location that
 595                  * had a probe in the module vaddr area which already
 596                  * freed. So, the instruction slot has already been
 597                  * released. We need a new slot for the new probe.
 598                  */
 599                 ret = arch_prepare_kprobe(ap);
 600                 if (ret)
 601                         /*
 602                          * Even if fail to allocate new slot, don't need to
 603                          * free aggr_probe. It will be used next time, or
 604                          * freed by unregister_kprobe.
 605                          */
 606                         return ret;
 607
 608                 /*
 609                  * Clear gone flag to prevent allocating new slot again, and
 610                  * set disabled flag because it is not armed yet.
 611                  */
 612                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
 613                             | KPROBE_FLAG_DISABLED;
 614         }
 615
 616         copy_kprobe(ap, p);
 617         return add_new_kprobe(ap, p);
 618 }
 619
 620 /* Try to disable aggr_kprobe, and return 1 if succeeded.*/
 621 static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p)
 622 {
 623         struct kprobe *kp;
 624
 625         list_for_each_entry_rcu(kp, &p->list, list) {
 626                 if (!kprobe_disabled(kp))
 627                         /*
 628                          * There is an active probe on the list.
 629                          * We can't disable aggr_kprobe.
 630                          */
 631                         return 0;
 632         }
 633         p->flags |= KPROBE_FLAG_DISABLED;
 634         return 1;
 635 }
 636
 637 static int __kprobes in_kprobes_functions(unsigned long addr)
 638 {
 639         struct kprobe_blackpoint *kb;
 640
 641         if (addr >= (unsigned long)__kprobes_text_start &&
 642             addr < (unsigned long)__kprobes_text_end)
 643                 return -EINVAL;
 644         /*
 645          * If there exists a kprobe_blacklist, verify and
 646          * fail any probe registration in the prohibited area
 647          */
 648         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
 649                 if (kb->start_addr) {
 650                         if (addr >= kb->start_addr &&
 651                             addr < (kb->start_addr + kb->range))
 652                                 return -EINVAL;
 653                 }
 654         }
 655         return 0;
 656 }
 657
 658 /*
 659  * If we have a symbol_name argument, look it up and add the offset field
 660  * to it. This way, we can specify a relative address to a symbol.
 661  */
 662 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
 663 {
 664         kprobe_opcode_t *addr = p->addr;
 665         if (p->symbol_name) {
 666                 if (addr)
 667                         return NULL;
 668                 kprobe_lookup_name(p->symbol_name, addr);
 669         }
 670
 671         if (!addr)
 672                 return NULL;
 673         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
 674 }
 675
 676 int __kprobes register_kprobe(struct kprobe *p)
 677 {
 678         int ret = 0;
 679         struct kprobe *old_p;
 680         struct module *probed_mod;
 681         kprobe_opcode_t *addr;
 682
 683         addr = kprobe_addr(p);
 684         if (!addr)
 685                 return -EINVAL;
 686         p->addr = addr;
 687
 688         preempt_disable();
 689         if (!kernel_text_address((unsigned long) p->addr) ||
 690             in_kprobes_functions((unsigned long) p->addr)) {
 691                 preempt_enable();
 692                 return -EINVAL;
 693         }
 694
 695         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
 696         p->flags &= KPROBE_FLAG_DISABLED;
 697
 698         /*
 699          * Check if are we probing a module.
 700          */
 701         probed_mod = __module_text_address((unsigned long) p->addr);
 702         if (probed_mod) {
 703                 /*
 704                  * We must hold a refcount of the probed module while updating
 705                  * its code to prohibit unexpected unloading.
 706                  */
 707                 if (unlikely(!try_module_get(probed_mod))) {
 708                         preempt_enable();
 709                         return -EINVAL;
 710                 }
 711                 /*
 712                  * If the module freed .init.text, we couldn't insert
 713                  * kprobes in there.
 714                  */
 715                 if (within_module_init((unsigned long)p->addr, probed_mod) &&
 716                     probed_mod->state != MODULE_STATE_COMING) {
 717                         module_put(probed_mod);
 718                         preempt_enable();
 719                         return -EINVAL;
 720                 }
 721         }
 722         preempt_enable();
 723
 724         p->nmissed = 0;
 725         INIT_LIST_HEAD(&p->list);
 726         mutex_lock(&kprobe_mutex);
 727         old_p = get_kprobe(p->addr);
 728         if (old_p) {
 729                 ret = register_aggr_kprobe(old_p, p);
 730                 goto out;
 731         }
 732
 733         mutex_lock(&text_mutex);
 734         ret = arch_prepare_kprobe(p);
 735         if (ret)
 736                 goto out_unlock_text;
 737
 738         INIT_HLIST_NODE(&p->hlist);
 739         hlist_add_head_rcu(&p->hlist,
 740                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 741
 742         if (!kprobes_all_disarmed && !kprobe_disabled(p))
 743                 arch_arm_kprobe(p);
 744
 745 out_unlock_text:
 746         mutex_unlock(&text_mutex);
 747 out:
 748         mutex_unlock(&kprobe_mutex);
 749
 750         if (probed_mod)
 751                 module_put(probed_mod);
 752
 753         return ret;
 754 }
 755 EXPORT_SYMBOL_GPL(register_kprobe);
 756
 757 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
 758 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
 759 {
 760         struct kprobe *old_p, *list_p;
 761
 762         old_p = get_kprobe(p->addr);
 763         if (unlikely(!old_p))
 764                 return NULL;
 765
 766         if (p != old_p) {
 767                 list_for_each_entry_rcu(list_p, &old_p->list, list)
 768                         if (list_p == p)
 769                         /* kprobe p is a valid probe */
 770                                 goto valid;
 771                 return NULL;
 772         }
 773 valid:
 774         return old_p;
 775 }
 776
 777 /*
 778  * Unregister a kprobe without a scheduler synchronization.
 779  */
 780 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
 781 {
 782         struct kprobe *old_p, *list_p;
 783
 784         old_p = __get_valid_kprobe(p);
 785         if (old_p == NULL)
 786                 return -EINVAL;
 787
 788         if (old_p == p ||
 789             (old_p->pre_handler == aggr_pre_handler &&
 790              list_is_singular(&old_p->list))) {
 791                 /*
 792                  * Only probe on the hash list. Disarm only if kprobes are
 793                  * enabled and not gone - otherwise, the breakpoint would
 794                  * already have been removed. We save on flushing icache.
 795                  */
 796                 if (!kprobes_all_disarmed && !kprobe_disabled(old_p))
 797                         disarm_kprobe(p);
 798                 hlist_del_rcu(&old_p->hlist);
 799         } else {
 800                 if (p->break_handler && !kprobe_gone(p))
 801                         old_p->break_handler = NULL;
 802                 if (p->post_handler && !kprobe_gone(p)) {
 803                         list_for_each_entry_rcu(list_p, &old_p->list, list) {
 804                                 if ((list_p != p) && (list_p->post_handler))
 805                                         goto noclean;
 806                         }
 807                         old_p->post_handler = NULL;
 808                 }
 809 noclean:
 810                 list_del_rcu(&p->list);
 811                 if (!kprobe_disabled(old_p)) {
 812                         try_to_disable_aggr_kprobe(old_p);
 813                         if (!kprobes_all_disarmed && kprobe_disabled(old_p))
 814                                 disarm_kprobe(old_p);
 815                 }
 816         }
 817         return 0;
 818 }
 819
 820 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
 821 {
 822         struct kprobe *old_p;
 823
 824         if (list_empty(&p->list))
 825                 arch_remove_kprobe(p);
 826         else if (list_is_singular(&p->list)) {
 827                 /* "p" is the last child of an aggr_kprobe */
 828                 old_p = list_entry(p->list.next, struct kprobe, list);
 829                 list_del(&p->list);
 830                 arch_remove_kprobe(old_p);
 831                 kfree(old_p);
 832         }
 833 }
 834
 835 int __kprobes register_kprobes(struct kprobe **kps, int num)
 836 {
 837         int i, ret = 0;
 838
 839         if (num <= 0)
 840                 return -EINVAL;
 841         for (i = 0; i < num; i++) {
 842                 ret = register_kprobe(kps[i]);
 843                 if (ret < 0) {
 844                         if (i > 0)
 845                                 unregister_kprobes(kps, i);
 846                         break;
 847                 }
 848         }
 849         return ret;
 850 }
 851 EXPORT_SYMBOL_GPL(register_kprobes);
 852
 853 void __kprobes unregister_kprobe(struct kprobe *p)
 854 {
 855         unregister_kprobes(&p, 1);
 856 }
 857 EXPORT_SYMBOL_GPL(unregister_kprobe);
 858
 859 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
 860 {
 861         int i;
 862
 863         if (num <= 0)
 864                 return;
 865         mutex_lock(&kprobe_mutex);
 866         for (i = 0; i < num; i++)
 867                 if (__unregister_kprobe_top(kps[i]) < 0)
 868                         kps[i]->addr = NULL;
 869         mutex_unlock(&kprobe_mutex);
 870
 871         synchronize_sched();
 872         for (i = 0; i < num; i++)
 873                 if (kps[i]->addr)
 874                         __unregister_kprobe_bottom(kps[i]);
 875 }
 876 EXPORT_SYMBOL_GPL(unregister_kprobes);
 877
 878 static struct notifier_block kprobe_exceptions_nb = {
 879         .notifier_call = kprobe_exceptions_notify,
 880         .priority = 0x7fffffff /* we need to be notified first */
 881 };
 882
 883 unsigned long __weak arch_deref_entry_point(void *entry)
 884 {
 885         return (unsigned long)entry;
 886 }
 887
 888 int __kprobes register_jprobes(struct jprobe **jps, int num)
 889 {
 890         struct jprobe *jp;
 891         int ret = 0, i;
 892
 893         if (num <= 0)
 894                 return -EINVAL;
 895         for (i = 0; i < num; i++) {
 896                 unsigned long addr;
 897                 jp = jps[i];
 898                 addr = arch_deref_entry_point(jp->entry);
 899
 900                 if (!kernel_text_address(addr))
 901                         ret = -EINVAL;
 902                 else {
 903                         /* Todo: Verify probepoint is a function entry point */
 904                         jp->kp.pre_handler = setjmp_pre_handler;
 905                         jp->kp.break_handler = longjmp_break_handler;
 906                         ret = register_kprobe(&jp->kp);
 907                 }
 908                 if (ret < 0) {
 909                         if (i > 0)
 910                                 unregister_jprobes(jps, i);
 911                         break;
 912                 }
 913         }
 914         return ret;
 915 }
 916 EXPORT_SYMBOL_GPL(register_jprobes);
 917
 918 int __kprobes register_jprobe(struct jprobe *jp)
 919 {
 920         return register_jprobes(&jp, 1);
 921 }
 922 EXPORT_SYMBOL_GPL(register_jprobe);
 923
 924 void __kprobes unregister_jprobe(struct jprobe *jp)
 925 {
 926         unregister_jprobes(&jp, 1);
 927 }
 928 EXPORT_SYMBOL_GPL(unregister_jprobe);
 929
 930 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
 931 {
 932         int i;
 933
 934         if (num <= 0)
 935                 return;
 936         mutex_lock(&kprobe_mutex);
 937         for (i = 0; i < num; i++)
 938                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
 939                         jps[i]->kp.addr = NULL;
 940         mutex_unlock(&kprobe_mutex);
 941
 942         synchronize_sched();
 943         for (i = 0; i < num; i++) {
 944                 if (jps[i]->kp.addr)
 945                         __unregister_kprobe_bottom(&jps[i]->kp);
 946         }
 947 }
 948 EXPORT_SYMBOL_GPL(unregister_jprobes);
 949
 950 #ifdef CONFIG_KRETPROBES
 951 /*
 952  * This kprobe pre_handler is registered with every kretprobe. When probe
 953  * hits it will set up the return probe.
 954  */
 955 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
 956                                            struct pt_regs *regs)
 957 {
 958         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
 959         unsigned long hash, flags = 0;
 960         struct kretprobe_instance *ri;
 961
 962         /*TODO: consider to only swap the RA after the last pre_handler fired */
 963         hash = hash_ptr(current, KPROBE_HASH_BITS);
 964         spin_lock_irqsave(&rp->lock, flags);
 965         if (!hlist_empty(&rp->free_instances)) {
 966                 ri = hlist_entry(rp->free_instances.first,
 967                                 struct kretprobe_instance, hlist);
 968                 hlist_del(&ri->hlist);
 969                 spin_unlock_irqrestore(&rp->lock, flags);
 970
 971                 ri->rp = rp;
 972                 ri->task = current;
 973
 974                 if (rp->entry_handler && rp->entry_handler(ri, regs))
 975                         return 0;
 976
 977                 arch_prepare_kretprobe(ri, regs);
 978
 979                 /* XXX(hch): why is there no hlist_move_head? */
 980                 INIT_HLIST_NODE(&ri->hlist);
 981                 kretprobe_table_lock(hash, &flags);
 982                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
 983                 kretprobe_table_unlock(hash, &flags);
 984         } else {
 985                 rp->nmissed++;
 986                 spin_unlock_irqrestore(&rp->lock, flags);
 987         }
 988         return 0;
 989 }
 990
 991 int __kprobes register_kretprobe(struct kretprobe *rp)
 992 {
 993         int ret = 0;
 994         struct kretprobe_instance *inst;
 995         int i;
 996         void *addr;
 997
 998         if (kretprobe_blacklist_size) {
 999                 addr = kprobe_addr(&rp->kp);
1000                 if (!addr)
1001                         return -EINVAL;
1002
1003                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1004                         if (kretprobe_blacklist[i].addr == addr)
1005                                 return -EINVAL;
1006                 }
1007         }
1008
1009         rp->kp.pre_handler = pre_handler_kretprobe;
1010         rp->kp.post_handler = NULL;
1011         rp->kp.fault_handler = NULL;
1012         rp->kp.break_handler = NULL;
1013
1014         /* Pre-allocate memory for max kretprobe instances */
1015         if (rp->maxactive <= 0) {
1016 #ifdef CONFIG_PREEMPT
1017                 rp->maxactive = max(10, 2 * NR_CPUS);
1018 #else
1019                 rp->maxactive = NR_CPUS;
1020 #endif
1021         }
1022         spin_lock_init(&rp->lock);
1023         INIT_HLIST_HEAD(&rp->free_instances);
1024         for (i = 0; i < rp->maxactive; i++) {
1025                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1026                                rp->data_size, GFP_KERNEL);
1027                 if (inst == NULL) {
1028                         free_rp_inst(rp);
1029                         return -ENOMEM;
1030                 }
1031                 INIT_HLIST_NODE(&inst->hlist);
1032                 hlist_add_head(&inst->hlist, &rp->free_instances);
1033         }
1034
1035         rp->nmissed = 0;
1036         /* Establish function entry probe point */
1037         ret = register_kprobe(&rp->kp);
1038         if (ret != 0)
1039                 free_rp_inst(rp);
1040         return ret;
1041 }
1042 EXPORT_SYMBOL_GPL(register_kretprobe);
1043
1044 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1045 {
1046         int ret = 0, i;
1047
1048         if (num <= 0)
1049                 return -EINVAL;
1050         for (i = 0; i < num; i++) {
1051                 ret = register_kretprobe(rps[i]);
1052                 if (ret < 0) {
1053                         if (i > 0)
1054                                 unregister_kretprobes(rps, i);
1055                         break;
1056                 }
1057         }
1058         return ret;
1059 }
1060 EXPORT_SYMBOL_GPL(register_kretprobes);
1061
1062 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1063 {
1064         unregister_kretprobes(&rp, 1);
1065 }
1066 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1067
1068 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1069 {
1070         int i;
1071
1072         if (num <= 0)
1073                 return;
1074         mutex_lock(&kprobe_mutex);
1075         for (i = 0; i < num; i++)
1076                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1077                         rps[i]->kp.addr = NULL;
1078         mutex_unlock(&kprobe_mutex);
1079
1080         synchronize_sched();
1081         for (i = 0; i < num; i++) {
1082                 if (rps[i]->kp.addr) {
1083                         __unregister_kprobe_bottom(&rps[i]->kp);
1084                         cleanup_rp_inst(rps[i]);
1085                 }
1086         }
1087 }
1088 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1089
1090 #else /* CONFIG_KRETPROBES */
1091 int __kprobes register_kretprobe(struct kretprobe *rp)
1092 {
1093         return -ENOSYS;
1094 }
1095 EXPORT_SYMBOL_GPL(register_kretprobe);
1096
1097 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1098 {
1099         return -ENOSYS;
1100 }
1101 EXPORT_SYMBOL_GPL(register_kretprobes);
1102
1103 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1104 {
1105 }
1106 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1107
1108 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1109 {
1110 }
1111 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1112
1113 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1114                                            struct pt_regs *regs)
1115 {
1116         return 0;
1117 }
1118
1119 #endif /* CONFIG_KRETPROBES */
1120
1121 /* Set the kprobe gone and remove its instruction buffer. */
1122 static void __kprobes kill_kprobe(struct kprobe *p)
1123 {
1124         struct kprobe *kp;
1125
1126         p->flags |= KPROBE_FLAG_GONE;
1127         if (p->pre_handler == aggr_pre_handler) {
1128                 /*
1129                  * If this is an aggr_kprobe, we have to list all the
1130                  * chained probes and mark them GONE.
1131                  */
1132                 list_for_each_entry_rcu(kp, &p->list, list)
1133                         kp->flags |= KPROBE_FLAG_GONE;
1134                 p->post_handler = NULL;
1135                 p->break_handler = NULL;
1136         }
1137         /*
1138          * Here, we can remove insn_slot safely, because no thread calls
1139          * the original probed function (which will be freed soon) any more.
1140          */
1141         arch_remove_kprobe(p);
1142 }
1143
1144 /* Module notifier call back, checking kprobes on the module */
1145 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1146                                              unsigned long val, void *data)
1147 {
1148         struct module *mod = data;
1149         struct hlist_head *head;
1150         struct hlist_node *node;
1151         struct kprobe *p;
1152         unsigned int i;
1153         int checkcore = (val == MODULE_STATE_GOING);
1154
1155         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1156                 return NOTIFY_DONE;
1157
1158         /*
1159          * When MODULE_STATE_GOING was notified, both of module .text and
1160          * .init.text sections would be freed. When MODULE_STATE_LIVE was
1161          * notified, only .init.text section would be freed. We need to
1162          * disable kprobes which have been inserted in the sections.
1163          */
1164         mutex_lock(&kprobe_mutex);
1165         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1166                 head = &kprobe_table[i];
1167                 hlist_for_each_entry_rcu(p, node, head, hlist)
1168                         if (within_module_init((unsigned long)p->addr, mod) ||
1169                             (checkcore &&
1170                              within_module_core((unsigned long)p->addr, mod))) {
1171                                 /*
1172                                  * The vaddr this probe is installed will soon
1173                                  * be vfreed buy not synced to disk. Hence,
1174                                  * disarming the breakpoint isn't needed.
1175                                  */
1176                                 kill_kprobe(p);
1177                         }
1178         }
1179         mutex_unlock(&kprobe_mutex);
1180         return NOTIFY_DONE;
1181 }
1182
1183 static struct notifier_block kprobe_module_nb = {
1184         .notifier_call = kprobes_module_callback,
1185         .priority = 0
1186 };
1187
1188 static int __init init_kprobes(void)
1189 {
1190         int i, err = 0;
1191         unsigned long offset = 0, size = 0;
1192         char *modname, namebuf[128];
1193         const char *symbol_name;
1194         void *addr;
1195         struct kprobe_blackpoint *kb;
1196
1197         /* FIXME allocate the probe table, currently defined statically */
1198         /* initialize all list heads */
1199         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1200                 INIT_HLIST_HEAD(&kprobe_table[i]);
1201                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1202                 spin_lock_init(&(kretprobe_table_locks[i].lock));
1203         }
1204
1205         /*
1206          * Lookup and populate the kprobe_blacklist.
1207          *
1208          * Unlike the kretprobe blacklist, we'll need to determine
1209          * the range of addresses that belong to the said functions,
1210          * since a kprobe need not necessarily be at the beginning
1211          * of a function.
1212          */
1213         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1214                 kprobe_lookup_name(kb->name, addr);
1215                 if (!addr)
1216                         continue;
1217
1218                 kb->start_addr = (unsigned long)addr;
1219                 symbol_name = kallsyms_lookup(kb->start_addr,
1220                                 &size, &offset, &modname, namebuf);
1221                 if (!symbol_name)
1222                         kb->range = 0;
1223                 else
1224                         kb->range = size;
1225         }
1226
1227         if (kretprobe_blacklist_size) {
1228                 /* lookup the function address from its name */
1229                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1230                         kprobe_lookup_name(kretprobe_blacklist[i].name,
1231                                            kretprobe_blacklist[i].addr);
1232                         if (!kretprobe_blacklist[i].addr)
1233                                 printk("kretprobe: lookup failed: %s\n",
1234                                        kretprobe_blacklist[i].name);
1235                 }
1236         }
1237
1238         /* By default, kprobes are armed */
1239         kprobes_all_disarmed = false;
1240
1241         err = arch_init_kprobes();
1242         if (!err)
1243                 err = register_die_notifier(&kprobe_exceptions_nb);
1244         if (!err)
1245                 err = register_module_notifier(&kprobe_module_nb);
1246
1247         kprobes_initialized = (err == 0);
1248
1249         if (!err)
1250                 init_test_probes();
1251         return err;
1252 }
1253
1254 #ifdef CONFIG_DEBUG_FS
1255 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
1256                 const char *sym, int offset,char *modname)
1257 {
1258         char *kprobe_type;
1259
1260         if (p->pre_handler == pre_handler_kretprobe)
1261                 kprobe_type = "r";
1262         else if (p->pre_handler == setjmp_pre_handler)
1263                 kprobe_type = "j";
1264         else
1265                 kprobe_type = "k";
1266         if (sym)
1267                 seq_printf(pi, "%p  %s  %s+0x%x  %s %s%s\n",
1268                         p->addr, kprobe_type, sym, offset,
1269                         (modname ? modname : " "),
1270                         (kprobe_gone(p) ? "[GONE]" : ""),
1271                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1272                          "[DISABLED]" : ""));
1273         else
1274                 seq_printf(pi, "%p  %s  %p %s%s\n",
1275                         p->addr, kprobe_type, p->addr,
1276                         (kprobe_gone(p) ? "[GONE]" : ""),
1277                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1278                          "[DISABLED]" : ""));
1279 }
1280
1281 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
1282 {
1283         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
1284 }
1285
1286 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
1287 {
1288         (*pos)++;
1289         if (*pos >= KPROBE_TABLE_SIZE)
1290                 return NULL;
1291         return pos;
1292 }
1293
1294 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
1295 {
1296         /* Nothing to do */
1297 }
1298
1299 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
1300 {
1301         struct hlist_head *head;
1302         struct hlist_node *node;
1303         struct kprobe *p, *kp;
1304         const char *sym = NULL;
1305         unsigned int i = *(loff_t *) v;
1306         unsigned long offset = 0;
1307         char *modname, namebuf[128];
1308
1309         head = &kprobe_table[i];
1310         preempt_disable();
1311         hlist_for_each_entry_rcu(p, node, head, hlist) {
1312                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
1313                                         &offset, &modname, namebuf);
1314                 if (p->pre_handler == aggr_pre_handler) {
1315                         list_for_each_entry_rcu(kp, &p->list, list)
1316                                 report_probe(pi, kp, sym, offset, modname);
1317                 } else
1318                         report_probe(pi, p, sym, offset, modname);
1319         }
1320         preempt_enable();
1321         return 0;
1322 }
1323
1324 static const struct seq_operations kprobes_seq_ops = {
1325         .start = kprobe_seq_start,
1326         .next  = kprobe_seq_next,
1327         .stop  = kprobe_seq_stop,
1328         .show  = show_kprobe_addr
1329 };
1330
1331 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
1332 {
1333         return seq_open(filp, &kprobes_seq_ops);
1334 }
1335
1336 static const struct file_operations debugfs_kprobes_operations = {
1337         .open           = kprobes_open,
1338         .read           = seq_read,
1339         .llseek         = seq_lseek,
1340         .release        = seq_release,
1341 };
1342
1343 /* Disable one kprobe */
1344 int __kprobes disable_kprobe(struct kprobe *kp)
1345 {
1346         int ret = 0;
1347         struct kprobe *p;
1348
1349         mutex_lock(&kprobe_mutex);
1350
1351         /* Check whether specified probe is valid. */
1352         p = __get_valid_kprobe(kp);
1353         if (unlikely(p == NULL)) {
1354                 ret = -EINVAL;
1355                 goto out;
1356         }
1357
1358         /* If the probe is already disabled (or gone), just return */
1359         if (kprobe_disabled(kp))
1360                 goto out;
1361
1362         kp->flags |= KPROBE_FLAG_DISABLED;
1363         if (p != kp)
1364                 /* When kp != p, p is always enabled. */
1365                 try_to_disable_aggr_kprobe(p);
1366
1367         if (!kprobes_all_disarmed && kprobe_disabled(p))
1368                 disarm_kprobe(p);
1369 out:
1370         mutex_unlock(&kprobe_mutex);
1371         return ret;
1372 }
1373 EXPORT_SYMBOL_GPL(disable_kprobe);
1374
1375 /* Enable one kprobe */
1376 int __kprobes enable_kprobe(struct kprobe *kp)
1377 {
1378         int ret = 0;
1379         struct kprobe *p;
1380
1381         mutex_lock(&kprobe_mutex);
1382
1383         /* Check whether specified probe is valid. */
1384         p = __get_valid_kprobe(kp);
1385         if (unlikely(p == NULL)) {
1386                 ret = -EINVAL;
1387                 goto out;
1388         }
1389
1390         if (kprobe_gone(kp)) {
1391                 /* This kprobe has gone, we couldn't enable it. */
1392                 ret = -EINVAL;
1393                 goto out;
1394         }
1395
1396         if (!kprobes_all_disarmed && kprobe_disabled(p))
1397                 arm_kprobe(p);
1398
1399         p->flags &= ~KPROBE_FLAG_DISABLED;
1400         if (p != kp)
1401                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1402 out:
1403         mutex_unlock(&kprobe_mutex);
1404         return ret;
1405 }
1406 EXPORT_SYMBOL_GPL(enable_kprobe);
1407
1408 static void __kprobes arm_all_kprobes(void)
1409 {
1410         struct hlist_head *head;
1411         struct hlist_node *node;
1412         struct kprobe *p;
1413         unsigned int i;
1414
1415         mutex_lock(&kprobe_mutex);
1416
1417         /* If kprobes are armed, just return */
1418         if (!kprobes_all_disarmed)
1419                 goto already_enabled;
1420
1421         mutex_lock(&text_mutex);
1422         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1423                 head = &kprobe_table[i];
1424                 hlist_for_each_entry_rcu(p, node, head, hlist)
1425                         if (!kprobe_disabled(p))
1426                                 arch_arm_kprobe(p);
1427         }
1428         mutex_unlock(&text_mutex);
1429
1430         kprobes_all_disarmed = false;
1431         printk(KERN_INFO "Kprobes globally enabled\n");
1432
1433 already_enabled:
1434         mutex_unlock(&kprobe_mutex);
1435         return;
1436 }
1437
1438 static void __kprobes disarm_all_kprobes(void)
1439 {
1440         struct hlist_head *head;
1441         struct hlist_node *node;
1442         struct kprobe *p;
1443         unsigned int i;
1444
1445         mutex_lock(&kprobe_mutex);
1446
1447         /* If kprobes are already disarmed, just return */
1448         if (kprobes_all_disarmed)
1449                 goto already_disabled;
1450
1451         kprobes_all_disarmed = true;
1452         printk(KERN_INFO "Kprobes globally disabled\n");
1453         mutex_lock(&text_mutex);
1454         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1455                 head = &kprobe_table[i];
1456                 hlist_for_each_entry_rcu(p, node, head, hlist) {
1457                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
1458                                 arch_disarm_kprobe(p);
1459                 }
1460         }
1461
1462         mutex_unlock(&text_mutex);
1463         mutex_unlock(&kprobe_mutex);
1464         /* Allow all currently running kprobes to complete */
1465         synchronize_sched();
1466         return;
1467
1468 already_disabled:
1469         mutex_unlock(&kprobe_mutex);
1470         return;
1471 }
1472
1473 /*
1474  * XXX: The debugfs bool file interface doesn't allow for callbacks
1475  * when the bool state is switched. We can reuse that facility when
1476  * available
1477  */
1478 static ssize_t read_enabled_file_bool(struct file *file,
1479                char __user *user_buf, size_t count, loff_t *ppos)
1480 {
1481         char buf[3];
1482
1483         if (!kprobes_all_disarmed)
1484                 buf[0] = '1';
1485         else
1486                 buf[0] = '0';
1487         buf[1] = '\n';
1488         buf[2] = 0x00;
1489         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
1490 }
1491
1492 static ssize_t write_enabled_file_bool(struct file *file,
1493                const char __user *user_buf, size_t count, loff_t *ppos)
1494 {
1495         char buf[32];
1496         int buf_size;
1497
1498         buf_size = min(count, (sizeof(buf)-1));
1499         if (copy_from_user(buf, user_buf, buf_size))
1500                 return -EFAULT;
1501
1502         switch (buf[0]) {
1503         case 'y':
1504         case 'Y':
1505         case '1':
1506                 arm_all_kprobes();
1507                 break;
1508         case 'n':
1509         case 'N':
1510         case '0':
1511                 disarm_all_kprobes();
1512                 break;
1513         }
1514
1515         return count;
1516 }
1517
1518 static const struct file_operations fops_kp = {
1519         .read =         read_enabled_file_bool,
1520         .write =        write_enabled_file_bool,
1521 };
1522
1523 static int __kprobes debugfs_kprobe_init(void)
1524 {
1525         struct dentry *dir, *file;
1526         unsigned int value = 1;
1527
1528         dir = debugfs_create_dir("kprobes", NULL);
1529         if (!dir)
1530                 return -ENOMEM;
1531
1532         file = debugfs_create_file("list", 0444, dir, NULL,
1533                                 &debugfs_kprobes_operations);
1534         if (!file) {
1535                 debugfs_remove(dir);
1536                 return -ENOMEM;
1537         }
1538
1539         file = debugfs_create_file("enabled", 0600, dir,
1540                                         &value, &fops_kp);
1541         if (!file) {
1542                 debugfs_remove(dir);
1543                 return -ENOMEM;
1544         }
1545
1546         return 0;
1547 }
1548
1549 late_initcall(debugfs_kprobe_init);
1550 #endif /* CONFIG_DEBUG_FS */
1551
1552 module_init(init_kprobes);
1553
1554 /* defined in arch/.../kernel/kprobes.c */
1555 EXPORT_SYMBOL_GPL(jprobe_return);