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         {"native_get_debugreg",},
  94         {"irq_entries_start",},
  95         {"common_interrupt",},
  96         {"mcount",},    /* mcount can be called from everywhere */
  97         {NULL}    /* Terminator */
  98 };
  99
 100 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 101 /*
 102  * kprobe->ainsn.insn points to the copy of the instruction to be
 103  * single-stepped. x86_64, POWER4 and above have no-exec support and
 104  * stepping on the instruction on a vmalloced/kmalloced/data page
 105  * is a recipe for disaster
 106  */
 107 #define INSNS_PER_PAGE  (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
 108
 109 struct kprobe_insn_page {
 110         struct list_head list;
 111         kprobe_opcode_t *insns;         /* Page of instruction slots */
 112         char slot_used[INSNS_PER_PAGE];
 113         int nused;
 114         int ngarbage;
 115 };
 116
 117 enum kprobe_slot_state {
 118         SLOT_CLEAN = 0,
 119         SLOT_DIRTY = 1,
 120         SLOT_USED = 2,
 121 };
 122
 123 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */
 124 static LIST_HEAD(kprobe_insn_pages);
 125 static int kprobe_garbage_slots;
 126 static int collect_garbage_slots(void);
 127
 128 static int __kprobes check_safety(void)
 129 {
 130         int ret = 0;
 131 #if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
 132         ret = freeze_processes();
 133         if (ret == 0) {
 134                 struct task_struct *p, *q;
 135                 do_each_thread(p, q) {
 136                         if (p != current && p->state == TASK_RUNNING &&
 137                             p->pid != 0) {
 138                                 printk("Check failed: %s is running\n",p->comm);
 139                                 ret = -1;
 140                                 goto loop_end;
 141                         }
 142                 } while_each_thread(p, q);
 143         }
 144 loop_end:
 145         thaw_processes();
 146 #else
 147         synchronize_sched();
 148 #endif
 149         return ret;
 150 }
 151
 152 /**
 153  * __get_insn_slot() - Find a slot on an executable page for an instruction.
 154  * We allocate an executable page if there's no room on existing ones.
 155  */
 156 static kprobe_opcode_t __kprobes *__get_insn_slot(void)
 157 {
 158         struct kprobe_insn_page *kip;
 159
 160  retry:
 161         list_for_each_entry(kip, &kprobe_insn_pages, list) {
 162                 if (kip->nused < INSNS_PER_PAGE) {
 163                         int i;
 164                         for (i = 0; i < INSNS_PER_PAGE; i++) {
 165                                 if (kip->slot_used[i] == SLOT_CLEAN) {
 166                                         kip->slot_used[i] = SLOT_USED;
 167                                         kip->nused++;
 168                                         return kip->insns + (i * MAX_INSN_SIZE);
 169                                 }
 170                         }
 171                         /* Surprise!  No unused slots.  Fix kip->nused. */
 172                         kip->nused = INSNS_PER_PAGE;
 173                 }
 174         }
 175
 176         /* If there are any garbage slots, collect it and try again. */
 177         if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
 178                 goto retry;
 179         }
 180         /* All out of space.  Need to allocate a new page. Use slot 0. */
 181         kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
 182         if (!kip)
 183                 return NULL;
 184
 185         /*
 186          * Use module_alloc so this page is within +/- 2GB of where the
 187          * kernel image and loaded module images reside. This is required
 188          * so x86_64 can correctly handle the %rip-relative fixups.
 189          */
 190         kip->insns = module_alloc(PAGE_SIZE);
 191         if (!kip->insns) {
 192                 kfree(kip);
 193                 return NULL;
 194         }
 195         INIT_LIST_HEAD(&kip->list);
 196         list_add(&kip->list, &kprobe_insn_pages);
 197         memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
 198         kip->slot_used[0] = SLOT_USED;
 199         kip->nused = 1;
 200         kip->ngarbage = 0;
 201         return kip->insns;
 202 }
 203
 204 kprobe_opcode_t __kprobes *get_insn_slot(void)
 205 {
 206         kprobe_opcode_t *ret;
 207         mutex_lock(&kprobe_insn_mutex);
 208         ret = __get_insn_slot();
 209         mutex_unlock(&kprobe_insn_mutex);
 210         return ret;
 211 }
 212
 213 /* Return 1 if all garbages are collected, otherwise 0. */
 214 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
 215 {
 216         kip->slot_used[idx] = SLOT_CLEAN;
 217         kip->nused--;
 218         if (kip->nused == 0) {
 219                 /*
 220                  * Page is no longer in use.  Free it unless
 221                  * it's the last one.  We keep the last one
 222                  * so as not to have to set it up again the
 223                  * next time somebody inserts a probe.
 224                  */
 225                 if (!list_is_singular(&kprobe_insn_pages)) {
 226                         list_del(&kip->list);
 227                         module_free(NULL, kip->insns);
 228                         kfree(kip);
 229                 }
 230                 return 1;
 231         }
 232         return 0;
 233 }
 234
 235 static int __kprobes collect_garbage_slots(void)
 236 {
 237         struct kprobe_insn_page *kip, *next;
 238
 239         /* Ensure no-one is preepmted on the garbages */
 240         if (check_safety())
 241                 return -EAGAIN;
 242
 243         list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
 244                 int i;
 245                 if (kip->ngarbage == 0)
 246                         continue;
 247                 kip->ngarbage = 0;      /* we will collect all garbages */
 248                 for (i = 0; i < INSNS_PER_PAGE; i++) {
 249                         if (kip->slot_used[i] == SLOT_DIRTY &&
 250                             collect_one_slot(kip, i))
 251                                 break;
 252                 }
 253         }
 254         kprobe_garbage_slots = 0;
 255         return 0;
 256 }
 257
 258 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
 259 {
 260         struct kprobe_insn_page *kip;
 261
 262         mutex_lock(&kprobe_insn_mutex);
 263         list_for_each_entry(kip, &kprobe_insn_pages, list) {
 264                 if (kip->insns <= slot &&
 265                     slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
 266                         int i = (slot - kip->insns) / MAX_INSN_SIZE;
 267                         if (dirty) {
 268                                 kip->slot_used[i] = SLOT_DIRTY;
 269                                 kip->ngarbage++;
 270                         } else
 271                                 collect_one_slot(kip, i);
 272                         break;
 273                 }
 274         }
 275
 276         if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
 277                 collect_garbage_slots();
 278
 279         mutex_unlock(&kprobe_insn_mutex);
 280 }
 281 #endif
 282
 283 /* We have preemption disabled.. so it is safe to use __ versions */
 284 static inline void set_kprobe_instance(struct kprobe *kp)
 285 {
 286         __get_cpu_var(kprobe_instance) = kp;
 287 }
 288
 289 static inline void reset_kprobe_instance(void)
 290 {
 291         __get_cpu_var(kprobe_instance) = NULL;
 292 }
 293
 294 /*
 295  * This routine is called either:
 296  *      - under the kprobe_mutex - during kprobe_[un]register()
 297  *                              OR
 298  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
 299  */
 300 struct kprobe __kprobes *get_kprobe(void *addr)
 301 {
 302         struct hlist_head *head;
 303         struct hlist_node *node;
 304         struct kprobe *p;
 305
 306         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
 307         hlist_for_each_entry_rcu(p, node, head, hlist) {
 308                 if (p->addr == addr)
 309                         return p;
 310         }
 311         return NULL;
 312 }
 313
 314 /* Arm a kprobe with text_mutex */
 315 static void __kprobes arm_kprobe(struct kprobe *kp)
 316 {
 317         mutex_lock(&text_mutex);
 318         arch_arm_kprobe(kp);
 319         mutex_unlock(&text_mutex);
 320 }
 321
 322 /* Disarm a kprobe with text_mutex */
 323 static void __kprobes disarm_kprobe(struct kprobe *kp)
 324 {
 325         mutex_lock(&text_mutex);
 326         arch_disarm_kprobe(kp);
 327         mutex_unlock(&text_mutex);
 328 }
 329
 330 /*
 331  * Aggregate handlers for multiple kprobes support - these handlers
 332  * take care of invoking the individual kprobe handlers on p->list
 333  */
 334 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
 335 {
 336         struct kprobe *kp;
 337
 338         list_for_each_entry_rcu(kp, &p->list, list) {
 339                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 340                         set_kprobe_instance(kp);
 341                         if (kp->pre_handler(kp, regs))
 342                                 return 1;
 343                 }
 344                 reset_kprobe_instance();
 345         }
 346         return 0;
 347 }
 348
 349 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
 350                                         unsigned long flags)
 351 {
 352         struct kprobe *kp;
 353
 354         list_for_each_entry_rcu(kp, &p->list, list) {
 355                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
 356                         set_kprobe_instance(kp);
 357                         kp->post_handler(kp, regs, flags);
 358                         reset_kprobe_instance();
 359                 }
 360         }
 361 }
 362
 363 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
 364                                         int trapnr)
 365 {
 366         struct kprobe *cur = __get_cpu_var(kprobe_instance);
 367
 368         /*
 369          * if we faulted "during" the execution of a user specified
 370          * probe handler, invoke just that probe's fault handler
 371          */
 372         if (cur && cur->fault_handler) {
 373                 if (cur->fault_handler(cur, regs, trapnr))
 374                         return 1;
 375         }
 376         return 0;
 377 }
 378
 379 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
 380 {
 381         struct kprobe *cur = __get_cpu_var(kprobe_instance);
 382         int ret = 0;
 383
 384         if (cur && cur->break_handler) {
 385                 if (cur->break_handler(cur, regs))
 386                         ret = 1;
 387         }
 388         reset_kprobe_instance();
 389         return ret;
 390 }
 391
 392 /* Walks the list and increments nmissed count for multiprobe case */
 393 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
 394 {
 395         struct kprobe *kp;
 396         if (p->pre_handler != aggr_pre_handler) {
 397                 p->nmissed++;
 398         } else {
 399                 list_for_each_entry_rcu(kp, &p->list, list)
 400                         kp->nmissed++;
 401         }
 402         return;
 403 }
 404
 405 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
 406                                 struct hlist_head *head)
 407 {
 408         struct kretprobe *rp = ri->rp;
 409
 410         /* remove rp inst off the rprobe_inst_table */
 411         hlist_del(&ri->hlist);
 412         INIT_HLIST_NODE(&ri->hlist);
 413         if (likely(rp)) {
 414                 spin_lock(&rp->lock);
 415                 hlist_add_head(&ri->hlist, &rp->free_instances);
 416                 spin_unlock(&rp->lock);
 417         } else
 418                 /* Unregistering */
 419                 hlist_add_head(&ri->hlist, head);
 420 }
 421
 422 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
 423                          struct hlist_head **head, unsigned long *flags)
 424 {
 425         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
 426         spinlock_t *hlist_lock;
 427
 428         *head = &kretprobe_inst_table[hash];
 429         hlist_lock = kretprobe_table_lock_ptr(hash);
 430         spin_lock_irqsave(hlist_lock, *flags);
 431 }
 432
 433 static void __kprobes kretprobe_table_lock(unsigned long hash,
 434         unsigned long *flags)
 435 {
 436         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
 437         spin_lock_irqsave(hlist_lock, *flags);
 438 }
 439
 440 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
 441         unsigned long *flags)
 442 {
 443         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
 444         spinlock_t *hlist_lock;
 445
 446         hlist_lock = kretprobe_table_lock_ptr(hash);
 447         spin_unlock_irqrestore(hlist_lock, *flags);
 448 }
 449
 450 void __kprobes kretprobe_table_unlock(unsigned long hash, unsigned long *flags)
 451 {
 452         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
 453         spin_unlock_irqrestore(hlist_lock, *flags);
 454 }
 455
 456 /*
 457  * This function is called from finish_task_switch when task tk becomes dead,
 458  * so that we can recycle any function-return probe instances associated
 459  * with this task. These left over instances represent probed functions
 460  * that have been called but will never return.
 461  */
 462 void __kprobes kprobe_flush_task(struct task_struct *tk)
 463 {
 464         struct kretprobe_instance *ri;
 465         struct hlist_head *head, empty_rp;
 466         struct hlist_node *node, *tmp;
 467         unsigned long hash, flags = 0;
 468
 469         if (unlikely(!kprobes_initialized))
 470                 /* Early boot.  kretprobe_table_locks not yet initialized. */
 471                 return;
 472
 473         hash = hash_ptr(tk, KPROBE_HASH_BITS);
 474         head = &kretprobe_inst_table[hash];
 475         kretprobe_table_lock(hash, &flags);
 476         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 477                 if (ri->task == tk)
 478                         recycle_rp_inst(ri, &empty_rp);
 479         }
 480         kretprobe_table_unlock(hash, &flags);
 481         INIT_HLIST_HEAD(&empty_rp);
 482         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 483                 hlist_del(&ri->hlist);
 484                 kfree(ri);
 485         }
 486 }
 487
 488 static inline void free_rp_inst(struct kretprobe *rp)
 489 {
 490         struct kretprobe_instance *ri;
 491         struct hlist_node *pos, *next;
 492
 493         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
 494                 hlist_del(&ri->hlist);
 495                 kfree(ri);
 496         }
 497 }
 498
 499 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
 500 {
 501         unsigned long flags, hash;
 502         struct kretprobe_instance *ri;
 503         struct hlist_node *pos, *next;
 504         struct hlist_head *head;
 505
 506         /* No race here */
 507         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
 508                 kretprobe_table_lock(hash, &flags);
 509                 head = &kretprobe_inst_table[hash];
 510                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
 511                         if (ri->rp == rp)
 512                                 ri->rp = NULL;
 513                 }
 514                 kretprobe_table_unlock(hash, &flags);
 515         }
 516         free_rp_inst(rp);
 517 }
 518
 519 /*
 520  * Keep all fields in the kprobe consistent
 521  */
 522 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
 523 {
 524         memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
 525         memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
 526 }
 527
 528 /*
 529 * Add the new probe to ap->list. Fail if this is the
 530 * second jprobe at the address - two jprobes can't coexist
 531 */
 532 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
 533 {
 534         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
 535         if (p->break_handler) {
 536                 if (ap->break_handler)
 537                         return -EEXIST;
 538                 list_add_tail_rcu(&p->list, &ap->list);
 539                 ap->break_handler = aggr_break_handler;
 540         } else
 541                 list_add_rcu(&p->list, &ap->list);
 542         if (p->post_handler && !ap->post_handler)
 543                 ap->post_handler = aggr_post_handler;
 544
 545         if (kprobe_disabled(ap) && !kprobe_disabled(p)) {
 546                 ap->flags &= ~KPROBE_FLAG_DISABLED;
 547                 if (!kprobes_all_disarmed)
 548                         /* Arm the breakpoint again. */
 549                         arm_kprobe(ap);
 550         }
 551         return 0;
 552 }
 553
 554 /*
 555  * Fill in the required fields of the "manager kprobe". Replace the
 556  * earlier kprobe in the hlist with the manager kprobe
 557  */
 558 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 559 {
 560         copy_kprobe(p, ap);
 561         flush_insn_slot(ap);
 562         ap->addr = p->addr;
 563         ap->flags = p->flags;
 564         ap->pre_handler = aggr_pre_handler;
 565         ap->fault_handler = aggr_fault_handler;
 566         /* We don't care the kprobe which has gone. */
 567         if (p->post_handler && !kprobe_gone(p))
 568                 ap->post_handler = aggr_post_handler;
 569         if (p->break_handler && !kprobe_gone(p))
 570                 ap->break_handler = aggr_break_handler;
 571
 572         INIT_LIST_HEAD(&ap->list);
 573         list_add_rcu(&p->list, &ap->list);
 574
 575         hlist_replace_rcu(&p->hlist, &ap->hlist);
 576 }
 577
 578 /*
 579  * This is the second or subsequent kprobe at the address - handle
 580  * the intricacies
 581  */
 582 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
 583                                           struct kprobe *p)
 584 {
 585         int ret = 0;
 586         struct kprobe *ap = old_p;
 587
 588         if (old_p->pre_handler != aggr_pre_handler) {
 589                 /* If old_p is not an aggr_probe, create new aggr_kprobe. */
 590                 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
 591                 if (!ap)
 592                         return -ENOMEM;
 593                 add_aggr_kprobe(ap, old_p);
 594         }
 595
 596         if (kprobe_gone(ap)) {
 597                 /*
 598                  * Attempting to insert new probe at the same location that
 599                  * had a probe in the module vaddr area which already
 600                  * freed. So, the instruction slot has already been
 601                  * released. We need a new slot for the new probe.
 602                  */
 603                 ret = arch_prepare_kprobe(ap);
 604                 if (ret)
 605                         /*
 606                          * Even if fail to allocate new slot, don't need to
 607                          * free aggr_probe. It will be used next time, or
 608                          * freed by unregister_kprobe.
 609                          */
 610                         return ret;
 611
 612                 /*
 613                  * Clear gone flag to prevent allocating new slot again, and
 614                  * set disabled flag because it is not armed yet.
 615                  */
 616                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
 617                             | KPROBE_FLAG_DISABLED;
 618         }
 619
 620         copy_kprobe(ap, p);
 621         return add_new_kprobe(ap, p);
 622 }
 623
 624 /* Try to disable aggr_kprobe, and return 1 if succeeded.*/
 625 static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p)
 626 {
 627         struct kprobe *kp;
 628
 629         list_for_each_entry_rcu(kp, &p->list, list) {
 630                 if (!kprobe_disabled(kp))
 631                         /*
 632                          * There is an active probe on the list.
 633                          * We can't disable aggr_kprobe.
 634                          */
 635                         return 0;
 636         }
 637         p->flags |= KPROBE_FLAG_DISABLED;
 638         return 1;
 639 }
 640
 641 static int __kprobes in_kprobes_functions(unsigned long addr)
 642 {
 643         struct kprobe_blackpoint *kb;
 644
 645         if (addr >= (unsigned long)__kprobes_text_start &&
 646             addr < (unsigned long)__kprobes_text_end)
 647                 return -EINVAL;
 648         /*
 649          * If there exists a kprobe_blacklist, verify and
 650          * fail any probe registration in the prohibited area
 651          */
 652         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
 653                 if (kb->start_addr) {
 654                         if (addr >= kb->start_addr &&
 655                             addr < (kb->start_addr + kb->range))
 656                                 return -EINVAL;
 657                 }
 658         }
 659         return 0;
 660 }
 661
 662 /*
 663  * If we have a symbol_name argument, look it up and add the offset field
 664  * to it. This way, we can specify a relative address to a symbol.
 665  */
 666 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
 667 {
 668         kprobe_opcode_t *addr = p->addr;
 669         if (p->symbol_name) {
 670                 if (addr)
 671                         return NULL;
 672                 kprobe_lookup_name(p->symbol_name, addr);
 673         }
 674
 675         if (!addr)
 676                 return NULL;
 677         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
 678 }
 679
 680 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
 681 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
 682 {
 683         struct kprobe *old_p, *list_p;
 684
 685         old_p = get_kprobe(p->addr);
 686         if (unlikely(!old_p))
 687                 return NULL;
 688
 689         if (p != old_p) {
 690                 list_for_each_entry_rcu(list_p, &old_p->list, list)
 691                         if (list_p == p)
 692                         /* kprobe p is a valid probe */
 693                                 goto valid;
 694                 return NULL;
 695         }
 696 valid:
 697         return old_p;
 698 }
 699
 700 /* Return error if the kprobe is being re-registered */
 701 static inline int check_kprobe_rereg(struct kprobe *p)
 702 {
 703         int ret = 0;
 704         struct kprobe *old_p;
 705
 706         mutex_lock(&kprobe_mutex);
 707         old_p = __get_valid_kprobe(p);
 708         if (old_p)
 709                 ret = -EINVAL;
 710         mutex_unlock(&kprobe_mutex);
 711         return ret;
 712 }
 713
 714 int __kprobes register_kprobe(struct kprobe *p)
 715 {
 716         int ret = 0;
 717         struct kprobe *old_p;
 718         struct module *probed_mod;
 719         kprobe_opcode_t *addr;
 720
 721         addr = kprobe_addr(p);
 722         if (!addr)
 723                 return -EINVAL;
 724         p->addr = addr;
 725
 726         ret = check_kprobe_rereg(p);
 727         if (ret)
 728                 return ret;
 729
 730         preempt_disable();
 731         if (!kernel_text_address((unsigned long) p->addr) ||
 732             in_kprobes_functions((unsigned long) p->addr)) {
 733                 preempt_enable();
 734                 return -EINVAL;
 735         }
 736
 737         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
 738         p->flags &= KPROBE_FLAG_DISABLED;
 739
 740         /*
 741          * Check if are we probing a module.
 742          */
 743         probed_mod = __module_text_address((unsigned long) p->addr);
 744         if (probed_mod) {
 745                 /*
 746                  * We must hold a refcount of the probed module while updating
 747                  * its code to prohibit unexpected unloading.
 748                  */
 749                 if (unlikely(!try_module_get(probed_mod))) {
 750                         preempt_enable();
 751                         return -EINVAL;
 752                 }
 753                 /*
 754                  * If the module freed .init.text, we couldn't insert
 755                  * kprobes in there.
 756                  */
 757                 if (within_module_init((unsigned long)p->addr, probed_mod) &&
 758                     probed_mod->state != MODULE_STATE_COMING) {
 759                         module_put(probed_mod);
 760                         preempt_enable();
 761                         return -EINVAL;
 762                 }
 763         }
 764         preempt_enable();
 765
 766         p->nmissed = 0;
 767         INIT_LIST_HEAD(&p->list);
 768         mutex_lock(&kprobe_mutex);
 769         old_p = get_kprobe(p->addr);
 770         if (old_p) {
 771                 ret = register_aggr_kprobe(old_p, p);
 772                 goto out;
 773         }
 774
 775         mutex_lock(&text_mutex);
 776         ret = arch_prepare_kprobe(p);
 777         if (ret)
 778                 goto out_unlock_text;
 779
 780         INIT_HLIST_NODE(&p->hlist);
 781         hlist_add_head_rcu(&p->hlist,
 782                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 783
 784         if (!kprobes_all_disarmed && !kprobe_disabled(p))
 785                 arch_arm_kprobe(p);
 786
 787 out_unlock_text:
 788         mutex_unlock(&text_mutex);
 789 out:
 790         mutex_unlock(&kprobe_mutex);
 791
 792         if (probed_mod)
 793                 module_put(probed_mod);
 794
 795         return ret;
 796 }
 797 EXPORT_SYMBOL_GPL(register_kprobe);
 798
 799 /*
 800  * Unregister a kprobe without a scheduler synchronization.
 801  */
 802 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
 803 {
 804         struct kprobe *old_p, *list_p;
 805
 806         old_p = __get_valid_kprobe(p);
 807         if (old_p == NULL)
 808                 return -EINVAL;
 809
 810         if (old_p == p ||
 811             (old_p->pre_handler == aggr_pre_handler &&
 812              list_is_singular(&old_p->list))) {
 813                 /*
 814                  * Only probe on the hash list. Disarm only if kprobes are
 815                  * enabled and not gone - otherwise, the breakpoint would
 816                  * already have been removed. We save on flushing icache.
 817                  */
 818                 if (!kprobes_all_disarmed && !kprobe_disabled(old_p))
 819                         disarm_kprobe(p);
 820                 hlist_del_rcu(&old_p->hlist);
 821         } else {
 822                 if (p->break_handler && !kprobe_gone(p))
 823                         old_p->break_handler = NULL;
 824                 if (p->post_handler && !kprobe_gone(p)) {
 825                         list_for_each_entry_rcu(list_p, &old_p->list, list) {
 826                                 if ((list_p != p) && (list_p->post_handler))
 827                                         goto noclean;
 828                         }
 829                         old_p->post_handler = NULL;
 830                 }
 831 noclean:
 832                 list_del_rcu(&p->list);
 833                 if (!kprobe_disabled(old_p)) {
 834                         try_to_disable_aggr_kprobe(old_p);
 835                         if (!kprobes_all_disarmed && kprobe_disabled(old_p))
 836                                 disarm_kprobe(old_p);
 837                 }
 838         }
 839         return 0;
 840 }
 841
 842 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
 843 {
 844         struct kprobe *old_p;
 845
 846         if (list_empty(&p->list))
 847                 arch_remove_kprobe(p);
 848         else if (list_is_singular(&p->list)) {
 849                 /* "p" is the last child of an aggr_kprobe */
 850                 old_p = list_entry(p->list.next, struct kprobe, list);
 851                 list_del(&p->list);
 852                 arch_remove_kprobe(old_p);
 853                 kfree(old_p);
 854         }
 855 }
 856
 857 int __kprobes register_kprobes(struct kprobe **kps, int num)
 858 {
 859         int i, ret = 0;
 860
 861         if (num <= 0)
 862                 return -EINVAL;
 863         for (i = 0; i < num; i++) {
 864                 ret = register_kprobe(kps[i]);
 865                 if (ret < 0) {
 866                         if (i > 0)
 867                                 unregister_kprobes(kps, i);
 868                         break;
 869                 }
 870         }
 871         return ret;
 872 }
 873 EXPORT_SYMBOL_GPL(register_kprobes);
 874
 875 void __kprobes unregister_kprobe(struct kprobe *p)
 876 {
 877         unregister_kprobes(&p, 1);
 878 }
 879 EXPORT_SYMBOL_GPL(unregister_kprobe);
 880
 881 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
 882 {
 883         int i;
 884
 885         if (num <= 0)
 886                 return;
 887         mutex_lock(&kprobe_mutex);
 888         for (i = 0; i < num; i++)
 889                 if (__unregister_kprobe_top(kps[i]) < 0)
 890                         kps[i]->addr = NULL;
 891         mutex_unlock(&kprobe_mutex);
 892
 893         synchronize_sched();
 894         for (i = 0; i < num; i++)
 895                 if (kps[i]->addr)
 896                         __unregister_kprobe_bottom(kps[i]);
 897 }
 898 EXPORT_SYMBOL_GPL(unregister_kprobes);
 899
 900 static struct notifier_block kprobe_exceptions_nb = {
 901         .notifier_call = kprobe_exceptions_notify,
 902         .priority = 0x7fffffff /* we need to be notified first */
 903 };
 904
 905 unsigned long __weak arch_deref_entry_point(void *entry)
 906 {
 907         return (unsigned long)entry;
 908 }
 909
 910 int __kprobes register_jprobes(struct jprobe **jps, int num)
 911 {
 912         struct jprobe *jp;
 913         int ret = 0, i;
 914
 915         if (num <= 0)
 916                 return -EINVAL;
 917         for (i = 0; i < num; i++) {
 918                 unsigned long addr;
 919                 jp = jps[i];
 920                 addr = arch_deref_entry_point(jp->entry);
 921
 922                 if (!kernel_text_address(addr))
 923                         ret = -EINVAL;
 924                 else {
 925                         /* Todo: Verify probepoint is a function entry point */
 926                         jp->kp.pre_handler = setjmp_pre_handler;
 927                         jp->kp.break_handler = longjmp_break_handler;
 928                         ret = register_kprobe(&jp->kp);
 929                 }
 930                 if (ret < 0) {
 931                         if (i > 0)
 932                                 unregister_jprobes(jps, i);
 933                         break;
 934                 }
 935         }
 936         return ret;
 937 }
 938 EXPORT_SYMBOL_GPL(register_jprobes);
 939
 940 int __kprobes register_jprobe(struct jprobe *jp)
 941 {
 942         return register_jprobes(&jp, 1);
 943 }
 944 EXPORT_SYMBOL_GPL(register_jprobe);
 945
 946 void __kprobes unregister_jprobe(struct jprobe *jp)
 947 {
 948         unregister_jprobes(&jp, 1);
 949 }
 950 EXPORT_SYMBOL_GPL(unregister_jprobe);
 951
 952 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
 953 {
 954         int i;
 955
 956         if (num <= 0)
 957                 return;
 958         mutex_lock(&kprobe_mutex);
 959         for (i = 0; i < num; i++)
 960                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
 961                         jps[i]->kp.addr = NULL;
 962         mutex_unlock(&kprobe_mutex);
 963
 964         synchronize_sched();
 965         for (i = 0; i < num; i++) {
 966                 if (jps[i]->kp.addr)
 967                         __unregister_kprobe_bottom(&jps[i]->kp);
 968         }
 969 }
 970 EXPORT_SYMBOL_GPL(unregister_jprobes);
 971
 972 #ifdef CONFIG_KRETPROBES
 973 /*
 974  * This kprobe pre_handler is registered with every kretprobe. When probe
 975  * hits it will set up the return probe.
 976  */
 977 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
 978                                            struct pt_regs *regs)
 979 {
 980         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
 981         unsigned long hash, flags = 0;
 982         struct kretprobe_instance *ri;
 983
 984         /*TODO: consider to only swap the RA after the last pre_handler fired */
 985         hash = hash_ptr(current, KPROBE_HASH_BITS);
 986         spin_lock_irqsave(&rp->lock, flags);
 987         if (!hlist_empty(&rp->free_instances)) {
 988                 ri = hlist_entry(rp->free_instances.first,
 989                                 struct kretprobe_instance, hlist);
 990                 hlist_del(&ri->hlist);
 991                 spin_unlock_irqrestore(&rp->lock, flags);
 992
 993                 ri->rp = rp;
 994                 ri->task = current;
 995
 996                 if (rp->entry_handler && rp->entry_handler(ri, regs))
 997                         return 0;
 998
 999                 arch_prepare_kretprobe(ri, regs);
1000
1001                 /* XXX(hch): why is there no hlist_move_head? */
1002                 INIT_HLIST_NODE(&ri->hlist);
1003                 kretprobe_table_lock(hash, &flags);
1004                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1005                 kretprobe_table_unlock(hash, &flags);
1006         } else {
1007                 rp->nmissed++;
1008                 spin_unlock_irqrestore(&rp->lock, flags);
1009         }
1010         return 0;
1011 }
1012
1013 int __kprobes register_kretprobe(struct kretprobe *rp)
1014 {
1015         int ret = 0;
1016         struct kretprobe_instance *inst;
1017         int i;
1018         void *addr;
1019
1020         if (kretprobe_blacklist_size) {
1021                 addr = kprobe_addr(&rp->kp);
1022                 if (!addr)
1023                         return -EINVAL;
1024
1025                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1026                         if (kretprobe_blacklist[i].addr == addr)
1027                                 return -EINVAL;
1028                 }
1029         }
1030
1031         rp->kp.pre_handler = pre_handler_kretprobe;
1032         rp->kp.post_handler = NULL;
1033         rp->kp.fault_handler = NULL;
1034         rp->kp.break_handler = NULL;
1035
1036         /* Pre-allocate memory for max kretprobe instances */
1037         if (rp->maxactive <= 0) {
1038 #ifdef CONFIG_PREEMPT
1039                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1040 #else
1041                 rp->maxactive = num_possible_cpus();
1042 #endif
1043         }
1044         spin_lock_init(&rp->lock);
1045         INIT_HLIST_HEAD(&rp->free_instances);
1046         for (i = 0; i < rp->maxactive; i++) {
1047                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1048                                rp->data_size, GFP_KERNEL);
1049                 if (inst == NULL) {
1050                         free_rp_inst(rp);
1051                         return -ENOMEM;
1052                 }
1053                 INIT_HLIST_NODE(&inst->hlist);
1054                 hlist_add_head(&inst->hlist, &rp->free_instances);
1055         }
1056
1057         rp->nmissed = 0;
1058         /* Establish function entry probe point */
1059         ret = register_kprobe(&rp->kp);
1060         if (ret != 0)
1061                 free_rp_inst(rp);
1062         return ret;
1063 }
1064 EXPORT_SYMBOL_GPL(register_kretprobe);
1065
1066 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1067 {
1068         int ret = 0, i;
1069
1070         if (num <= 0)
1071                 return -EINVAL;
1072         for (i = 0; i < num; i++) {
1073                 ret = register_kretprobe(rps[i]);
1074                 if (ret < 0) {
1075                         if (i > 0)
1076                                 unregister_kretprobes(rps, i);
1077                         break;
1078                 }
1079         }
1080         return ret;
1081 }
1082 EXPORT_SYMBOL_GPL(register_kretprobes);
1083
1084 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1085 {
1086         unregister_kretprobes(&rp, 1);
1087 }
1088 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1089
1090 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1091 {
1092         int i;
1093
1094         if (num <= 0)
1095                 return;
1096         mutex_lock(&kprobe_mutex);
1097         for (i = 0; i < num; i++)
1098                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1099                         rps[i]->kp.addr = NULL;
1100         mutex_unlock(&kprobe_mutex);
1101
1102         synchronize_sched();
1103         for (i = 0; i < num; i++) {
1104                 if (rps[i]->kp.addr) {
1105                         __unregister_kprobe_bottom(&rps[i]->kp);
1106                         cleanup_rp_inst(rps[i]);
1107                 }
1108         }
1109 }
1110 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1111
1112 #else /* CONFIG_KRETPROBES */
1113 int __kprobes register_kretprobe(struct kretprobe *rp)
1114 {
1115         return -ENOSYS;
1116 }
1117 EXPORT_SYMBOL_GPL(register_kretprobe);
1118
1119 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1120 {
1121         return -ENOSYS;
1122 }
1123 EXPORT_SYMBOL_GPL(register_kretprobes);
1124
1125 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1126 {
1127 }
1128 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1129
1130 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1131 {
1132 }
1133 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1134
1135 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1136                                            struct pt_regs *regs)
1137 {
1138         return 0;
1139 }
1140
1141 #endif /* CONFIG_KRETPROBES */
1142
1143 /* Set the kprobe gone and remove its instruction buffer. */
1144 static void __kprobes kill_kprobe(struct kprobe *p)
1145 {
1146         struct kprobe *kp;
1147
1148         p->flags |= KPROBE_FLAG_GONE;
1149         if (p->pre_handler == aggr_pre_handler) {
1150                 /*
1151                  * If this is an aggr_kprobe, we have to list all the
1152                  * chained probes and mark them GONE.
1153                  */
1154                 list_for_each_entry_rcu(kp, &p->list, list)
1155                         kp->flags |= KPROBE_FLAG_GONE;
1156                 p->post_handler = NULL;
1157                 p->break_handler = NULL;
1158         }
1159         /*
1160          * Here, we can remove insn_slot safely, because no thread calls
1161          * the original probed function (which will be freed soon) any more.
1162          */
1163         arch_remove_kprobe(p);
1164 }
1165
1166 void __kprobes dump_kprobe(struct kprobe *kp)
1167 {
1168         printk(KERN_WARNING "Dumping kprobe:\n");
1169         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
1170                kp->symbol_name, kp->addr, kp->offset);
1171 }
1172
1173 /* Module notifier call back, checking kprobes on the module */
1174 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
1175                                              unsigned long val, void *data)
1176 {
1177         struct module *mod = data;
1178         struct hlist_head *head;
1179         struct hlist_node *node;
1180         struct kprobe *p;
1181         unsigned int i;
1182         int checkcore = (val == MODULE_STATE_GOING);
1183
1184         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
1185                 return NOTIFY_DONE;
1186
1187         /*
1188          * When MODULE_STATE_GOING was notified, both of module .text and
1189          * .init.text sections would be freed. When MODULE_STATE_LIVE was
1190          * notified, only .init.text section would be freed. We need to
1191          * disable kprobes which have been inserted in the sections.
1192          */
1193         mutex_lock(&kprobe_mutex);
1194         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1195                 head = &kprobe_table[i];
1196                 hlist_for_each_entry_rcu(p, node, head, hlist)
1197                         if (within_module_init((unsigned long)p->addr, mod) ||
1198                             (checkcore &&
1199                              within_module_core((unsigned long)p->addr, mod))) {
1200                                 /*
1201                                  * The vaddr this probe is installed will soon
1202                                  * be vfreed buy not synced to disk. Hence,
1203                                  * disarming the breakpoint isn't needed.
1204                                  */
1205                                 kill_kprobe(p);
1206                         }
1207         }
1208         mutex_unlock(&kprobe_mutex);
1209         return NOTIFY_DONE;
1210 }
1211
1212 static struct notifier_block kprobe_module_nb = {
1213         .notifier_call = kprobes_module_callback,
1214         .priority = 0
1215 };
1216
1217 static int __init init_kprobes(void)
1218 {
1219         int i, err = 0;
1220         unsigned long offset = 0, size = 0;
1221         char *modname, namebuf[128];
1222         const char *symbol_name;
1223         void *addr;
1224         struct kprobe_blackpoint *kb;
1225
1226         /* FIXME allocate the probe table, currently defined statically */
1227         /* initialize all list heads */
1228         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1229                 INIT_HLIST_HEAD(&kprobe_table[i]);
1230                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
1231                 spin_lock_init(&(kretprobe_table_locks[i].lock));
1232         }
1233
1234         /*
1235          * Lookup and populate the kprobe_blacklist.
1236          *
1237          * Unlike the kretprobe blacklist, we'll need to determine
1238          * the range of addresses that belong to the said functions,
1239          * since a kprobe need not necessarily be at the beginning
1240          * of a function.
1241          */
1242         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1243                 kprobe_lookup_name(kb->name, addr);
1244                 if (!addr)
1245                         continue;
1246
1247                 kb->start_addr = (unsigned long)addr;
1248                 symbol_name = kallsyms_lookup(kb->start_addr,
1249                                 &size, &offset, &modname, namebuf);
1250                 if (!symbol_name)
1251                         kb->range = 0;
1252                 else
1253                         kb->range = size;
1254         }
1255
1256         if (kretprobe_blacklist_size) {
1257                 /* lookup the function address from its name */
1258                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1259                         kprobe_lookup_name(kretprobe_blacklist[i].name,
1260                                            kretprobe_blacklist[i].addr);
1261                         if (!kretprobe_blacklist[i].addr)
1262                                 printk("kretprobe: lookup failed: %s\n",
1263                                        kretprobe_blacklist[i].name);
1264                 }
1265         }
1266
1267         /* By default, kprobes are armed */
1268         kprobes_all_disarmed = false;
1269
1270         err = arch_init_kprobes();
1271         if (!err)
1272                 err = register_die_notifier(&kprobe_exceptions_nb);
1273         if (!err)
1274                 err = register_module_notifier(&kprobe_module_nb);
1275
1276         kprobes_initialized = (err == 0);
1277
1278         if (!err)
1279                 init_test_probes();
1280         return err;
1281 }
1282
1283 #ifdef CONFIG_DEBUG_FS
1284 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
1285                 const char *sym, int offset,char *modname)
1286 {
1287         char *kprobe_type;
1288
1289         if (p->pre_handler == pre_handler_kretprobe)
1290                 kprobe_type = "r";
1291         else if (p->pre_handler == setjmp_pre_handler)
1292                 kprobe_type = "j";
1293         else
1294                 kprobe_type = "k";
1295         if (sym)
1296                 seq_printf(pi, "%p  %s  %s+0x%x  %s %s%s\n",
1297                         p->addr, kprobe_type, sym, offset,
1298                         (modname ? modname : " "),
1299                         (kprobe_gone(p) ? "[GONE]" : ""),
1300                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1301                          "[DISABLED]" : ""));
1302         else
1303                 seq_printf(pi, "%p  %s  %p %s%s\n",
1304                         p->addr, kprobe_type, p->addr,
1305                         (kprobe_gone(p) ? "[GONE]" : ""),
1306                         ((kprobe_disabled(p) && !kprobe_gone(p)) ?
1307                          "[DISABLED]" : ""));
1308 }
1309
1310 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
1311 {
1312         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
1313 }
1314
1315 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
1316 {
1317         (*pos)++;
1318         if (*pos >= KPROBE_TABLE_SIZE)
1319                 return NULL;
1320         return pos;
1321 }
1322
1323 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
1324 {
1325         /* Nothing to do */
1326 }
1327
1328 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
1329 {
1330         struct hlist_head *head;
1331         struct hlist_node *node;
1332         struct kprobe *p, *kp;
1333         const char *sym = NULL;
1334         unsigned int i = *(loff_t *) v;
1335         unsigned long offset = 0;
1336         char *modname, namebuf[128];
1337
1338         head = &kprobe_table[i];
1339         preempt_disable();
1340         hlist_for_each_entry_rcu(p, node, head, hlist) {
1341                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
1342                                         &offset, &modname, namebuf);
1343                 if (p->pre_handler == aggr_pre_handler) {
1344                         list_for_each_entry_rcu(kp, &p->list, list)
1345                                 report_probe(pi, kp, sym, offset, modname);
1346                 } else
1347                         report_probe(pi, p, sym, offset, modname);
1348         }
1349         preempt_enable();
1350         return 0;
1351 }
1352
1353 static const struct seq_operations kprobes_seq_ops = {
1354         .start = kprobe_seq_start,
1355         .next  = kprobe_seq_next,
1356         .stop  = kprobe_seq_stop,
1357         .show  = show_kprobe_addr
1358 };
1359
1360 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
1361 {
1362         return seq_open(filp, &kprobes_seq_ops);
1363 }
1364
1365 static const struct file_operations debugfs_kprobes_operations = {
1366         .open           = kprobes_open,
1367         .read           = seq_read,
1368         .llseek         = seq_lseek,
1369         .release        = seq_release,
1370 };
1371
1372 /* Disable one kprobe */
1373 int __kprobes disable_kprobe(struct kprobe *kp)
1374 {
1375         int ret = 0;
1376         struct kprobe *p;
1377
1378         mutex_lock(&kprobe_mutex);
1379
1380         /* Check whether specified probe is valid. */
1381         p = __get_valid_kprobe(kp);
1382         if (unlikely(p == NULL)) {
1383                 ret = -EINVAL;
1384                 goto out;
1385         }
1386
1387         /* If the probe is already disabled (or gone), just return */
1388         if (kprobe_disabled(kp))
1389                 goto out;
1390
1391         kp->flags |= KPROBE_FLAG_DISABLED;
1392         if (p != kp)
1393                 /* When kp != p, p is always enabled. */
1394                 try_to_disable_aggr_kprobe(p);
1395
1396         if (!kprobes_all_disarmed && kprobe_disabled(p))
1397                 disarm_kprobe(p);
1398 out:
1399         mutex_unlock(&kprobe_mutex);
1400         return ret;
1401 }
1402 EXPORT_SYMBOL_GPL(disable_kprobe);
1403
1404 /* Enable one kprobe */
1405 int __kprobes enable_kprobe(struct kprobe *kp)
1406 {
1407         int ret = 0;
1408         struct kprobe *p;
1409
1410         mutex_lock(&kprobe_mutex);
1411
1412         /* Check whether specified probe is valid. */
1413         p = __get_valid_kprobe(kp);
1414         if (unlikely(p == NULL)) {
1415                 ret = -EINVAL;
1416                 goto out;
1417         }
1418
1419         if (kprobe_gone(kp)) {
1420                 /* This kprobe has gone, we couldn't enable it. */
1421                 ret = -EINVAL;
1422                 goto out;
1423         }
1424
1425         if (!kprobes_all_disarmed && kprobe_disabled(p))
1426                 arm_kprobe(p);
1427
1428         p->flags &= ~KPROBE_FLAG_DISABLED;
1429         if (p != kp)
1430                 kp->flags &= ~KPROBE_FLAG_DISABLED;
1431 out:
1432         mutex_unlock(&kprobe_mutex);
1433         return ret;
1434 }
1435 EXPORT_SYMBOL_GPL(enable_kprobe);
1436
1437 static void __kprobes arm_all_kprobes(void)
1438 {
1439         struct hlist_head *head;
1440         struct hlist_node *node;
1441         struct kprobe *p;
1442         unsigned int i;
1443
1444         mutex_lock(&kprobe_mutex);
1445
1446         /* If kprobes are armed, just return */
1447         if (!kprobes_all_disarmed)
1448                 goto already_enabled;
1449
1450         mutex_lock(&text_mutex);
1451         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1452                 head = &kprobe_table[i];
1453                 hlist_for_each_entry_rcu(p, node, head, hlist)
1454                         if (!kprobe_disabled(p))
1455                                 arch_arm_kprobe(p);
1456         }
1457         mutex_unlock(&text_mutex);
1458
1459         kprobes_all_disarmed = false;
1460         printk(KERN_INFO "Kprobes globally enabled\n");
1461
1462 already_enabled:
1463         mutex_unlock(&kprobe_mutex);
1464         return;
1465 }
1466
1467 static void __kprobes disarm_all_kprobes(void)
1468 {
1469         struct hlist_head *head;
1470         struct hlist_node *node;
1471         struct kprobe *p;
1472         unsigned int i;
1473
1474         mutex_lock(&kprobe_mutex);
1475
1476         /* If kprobes are already disarmed, just return */
1477         if (kprobes_all_disarmed)
1478                 goto already_disabled;
1479
1480         kprobes_all_disarmed = true;
1481         printk(KERN_INFO "Kprobes globally disabled\n");
1482         mutex_lock(&text_mutex);
1483         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
1484                 head = &kprobe_table[i];
1485                 hlist_for_each_entry_rcu(p, node, head, hlist) {
1486                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
1487                                 arch_disarm_kprobe(p);
1488                 }
1489         }
1490
1491         mutex_unlock(&text_mutex);
1492         mutex_unlock(&kprobe_mutex);
1493         /* Allow all currently running kprobes to complete */
1494         synchronize_sched();
1495         return;
1496
1497 already_disabled:
1498         mutex_unlock(&kprobe_mutex);
1499         return;
1500 }
1501
1502 /*
1503  * XXX: The debugfs bool file interface doesn't allow for callbacks
1504  * when the bool state is switched. We can reuse that facility when
1505  * available
1506  */
1507 static ssize_t read_enabled_file_bool(struct file *file,
1508                char __user *user_buf, size_t count, loff_t *ppos)
1509 {
1510         char buf[3];
1511
1512         if (!kprobes_all_disarmed)
1513                 buf[0] = '1';
1514         else
1515                 buf[0] = '0';
1516         buf[1] = '\n';
1517         buf[2] = 0x00;
1518         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
1519 }
1520
1521 static ssize_t write_enabled_file_bool(struct file *file,
1522                const char __user *user_buf, size_t count, loff_t *ppos)
1523 {
1524         char buf[32];
1525         int buf_size;
1526
1527         buf_size = min(count, (sizeof(buf)-1));
1528         if (copy_from_user(buf, user_buf, buf_size))
1529                 return -EFAULT;
1530
1531         switch (buf[0]) {
1532         case 'y':
1533         case 'Y':
1534         case '1':
1535                 arm_all_kprobes();
1536                 break;
1537         case 'n':
1538         case 'N':
1539         case '0':
1540                 disarm_all_kprobes();
1541                 break;
1542         }
1543
1544         return count;
1545 }
1546
1547 static const struct file_operations fops_kp = {
1548         .read =         read_enabled_file_bool,
1549         .write =        write_enabled_file_bool,
1550 };
1551
1552 static int __kprobes debugfs_kprobe_init(void)
1553 {
1554         struct dentry *dir, *file;
1555         unsigned int value = 1;
1556
1557         dir = debugfs_create_dir("kprobes", NULL);
1558         if (!dir)
1559                 return -ENOMEM;
1560
1561         file = debugfs_create_file("list", 0444, dir, NULL,
1562                                 &debugfs_kprobes_operations);
1563         if (!file) {
1564                 debugfs_remove(dir);
1565                 return -ENOMEM;
1566         }
1567
1568         file = debugfs_create_file("enabled", 0600, dir,
1569                                         &value, &fops_kp);
1570         if (!file) {
1571                 debugfs_remove(dir);
1572                 return -ENOMEM;
1573         }
1574
1575         return 0;
1576 }
1577
1578 late_initcall(debugfs_kprobe_init);
1579 #endif /* CONFIG_DEBUG_FS */
1580
1581 module_init(init_kprobes);
1582
1583 /* defined in arch/.../kernel/kprobes.c */
1584 EXPORT_SYMBOL_GPL(jprobe_return);