kernel/kprobes.c

   1 /*
   2  *  Kernel Probes (KProbes)
   3  *  kernel/kprobes.c
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  *
  19  * Copyright (C) IBM Corporation, 2002, 2004
  20  *
  21  * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
  22  *              Probes initial implementation (includes suggestions from
  23  *              Rusty Russell).
  24  * 2004-Aug     Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
  25  *              hlists and exceptions notifier as suggested by Andi Kleen.
  26  * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
  27  *              interface to access function arguments.
  28  * 2004-Sep     Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
  29  *              exceptions notifier to be first on the priority list.
  30  * 2005-May     Hien Nguyen <hien@us.ibm.com>, Jim Keniston
  31  *              <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
  32  *              <prasanna@in.ibm.com> added function-return probes.
  33  */
  34 #include <linux/kprobes.h>
  35 #include <linux/hash.h>
  36 #include <linux/init.h>
  37 #include <linux/slab.h>
  38 #include <linux/stddef.h>
  39 #include <linux/export.h>
  40 #include <linux/moduleloader.h>
  41 #include <linux/kallsyms.h>
  42 #include <linux/freezer.h>
  43 #include <linux/seq_file.h>
  44 #include <linux/debugfs.h>
  45 #include <linux/sysctl.h>
  46 #include <linux/kdebug.h>
  47 #include <linux/memory.h>
  48 #include <linux/ftrace.h>
  49 #include <linux/cpu.h>
  50 #include <linux/jump_label.h>
  51
  52 #include <asm-generic/sections.h>
  53 #include <asm/cacheflush.h>
  54 #include <asm/errno.h>
  55 #include <asm/uaccess.h>
  56
  57 #define KPROBE_HASH_BITS 6
  58 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
  59
  60
  61 /*
  62  * Some oddball architectures like 64bit powerpc have function descriptors
  63  * so this must be overridable.
  64  */
  65 #ifndef kprobe_lookup_name
  66 #define kprobe_lookup_name(name, addr) \
  67         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
  68 #endif
  69
  70 static int kprobes_initialized;
  71 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  72 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
  73
  74 /* NOTE: change this value only with kprobe_mutex held */
  75 static bool kprobes_all_disarmed;
  76
  77 /* This protects kprobe_table and optimizing_list */
  78 static DEFINE_MUTEX(kprobe_mutex);
  79 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
  80 static struct {
  81         raw_spinlock_t lock ____cacheline_aligned_in_smp;
  82 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
  83
  84 static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
  85 {
  86         return &(kretprobe_table_locks[hash].lock);
  87 }
  88
  89 /*
  90  * Normally, functions that we'd want to prohibit kprobes in, are marked
  91  * __kprobes. But, there are cases where such functions already belong to
  92  * a different section (__sched for preempt_schedule)
  93  *
  94  * For such cases, we now have a blacklist
  95  */
  96 static struct kprobe_blackpoint kprobe_blacklist[] = {
  97         {"preempt_schedule",},
  98         {"native_get_debugreg",},
  99         {"irq_entries_start",},
 100         {"common_interrupt",},
 101         {"mcount",},    /* mcount can be called from everywhere */
 102         {NULL}    /* Terminator */
 103 };
 104
 105 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 106 /*
 107  * kprobe->ainsn.insn points to the copy of the instruction to be
 108  * single-stepped. x86_64, POWER4 and above have no-exec support and
 109  * stepping on the instruction on a vmalloced/kmalloced/data page
 110  * is a recipe for disaster
 111  */
 112 struct kprobe_insn_page {
 113         struct list_head list;
 114         kprobe_opcode_t *insns;         /* Page of instruction slots */
 115         int nused;
 116         int ngarbage;
 117         char slot_used[];
 118 };
 119
 120 #define KPROBE_INSN_PAGE_SIZE(slots)                    \
 121         (offsetof(struct kprobe_insn_page, slot_used) + \
 122          (sizeof(char) * (slots)))
 123
 124 struct kprobe_insn_cache {
 125         struct list_head pages; /* list of kprobe_insn_page */
 126         size_t insn_size;       /* size of instruction slot */
 127         int nr_garbage;
 128 };
 129
 130 static int slots_per_page(struct kprobe_insn_cache *c)
 131 {
 132         return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
 133 }
 134
 135 enum kprobe_slot_state {
 136         SLOT_CLEAN = 0,
 137         SLOT_DIRTY = 1,
 138         SLOT_USED = 2,
 139 };
 140
 141 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
 142 static struct kprobe_insn_cache kprobe_insn_slots = {
 143         .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
 144         .insn_size = MAX_INSN_SIZE,
 145         .nr_garbage = 0,
 146 };
 147 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
 148
 149 /**
 150  * __get_insn_slot() - Find a slot on an executable page for an instruction.
 151  * We allocate an executable page if there's no room on existing ones.
 152  */
 153 static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
 154 {
 155         struct kprobe_insn_page *kip;
 156
 157  retry:
 158         list_for_each_entry(kip, &c->pages, list) {
 159                 if (kip->nused < slots_per_page(c)) {
 160                         int i;
 161                         for (i = 0; i < slots_per_page(c); i++) {
 162                                 if (kip->slot_used[i] == SLOT_CLEAN) {
 163                                         kip->slot_used[i] = SLOT_USED;
 164                                         kip->nused++;
 165                                         return kip->insns + (i * c->insn_size);
 166                                 }
 167                         }
 168                         /* kip->nused is broken. Fix it. */
 169                         kip->nused = slots_per_page(c);
 170                         WARN_ON(1);
 171                 }
 172         }
 173
 174         /* If there are any garbage slots, collect it and try again. */
 175         if (c->nr_garbage && collect_garbage_slots(c) == 0)
 176                 goto retry;
 177
 178         /* All out of space.  Need to allocate a new page. */
 179         kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
 180         if (!kip)
 181                 return NULL;
 182
 183         /*
 184          * Use module_alloc so this page is within +/- 2GB of where the
 185          * kernel image and loaded module images reside. This is required
 186          * so x86_64 can correctly handle the %rip-relative fixups.
 187          */
 188         kip->insns = module_alloc(PAGE_SIZE);
 189         if (!kip->insns) {
 190                 kfree(kip);
 191                 return NULL;
 192         }
 193         INIT_LIST_HEAD(&kip->list);
 194         memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
 195         kip->slot_used[0] = SLOT_USED;
 196         kip->nused = 1;
 197         kip->ngarbage = 0;
 198         list_add(&kip->list, &c->pages);
 199         return kip->insns;
 200 }
 201
 202
 203 kprobe_opcode_t __kprobes *get_insn_slot(void)
 204 {
 205         kprobe_opcode_t *ret = NULL;
 206
 207         mutex_lock(&kprobe_insn_mutex);
 208         ret = __get_insn_slot(&kprobe_insn_slots);
 209         mutex_unlock(&kprobe_insn_mutex);
 210
 211         return ret;
 212 }
 213
 214 /* Return 1 if all garbages are collected, otherwise 0. */
 215 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
 216 {
 217         kip->slot_used[idx] = SLOT_CLEAN;
 218         kip->nused--;
 219         if (kip->nused == 0) {
 220                 /*
 221                  * Page is no longer in use.  Free it unless
 222                  * it's the last one.  We keep the last one
 223                  * so as not to have to set it up again the
 224                  * next time somebody inserts a probe.
 225                  */
 226                 if (!list_is_singular(&kip->list)) {
 227                         list_del(&kip->list);
 228                         module_free(NULL, kip->insns);
 229                         kfree(kip);
 230                 }
 231                 return 1;
 232         }
 233         return 0;
 234 }
 235
 236 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
 237 {
 238         struct kprobe_insn_page *kip, *next;
 239
 240         /* Ensure no-one is interrupted on the garbages */
 241         synchronize_sched();
 242
 243         list_for_each_entry_safe(kip, next, &c->pages, list) {
 244                 int i;
 245                 if (kip->ngarbage == 0)
 246                         continue;
 247                 kip->ngarbage = 0;      /* we will collect all garbages */
 248                 for (i = 0; i < slots_per_page(c); i++) {
 249                         if (kip->slot_used[i] == SLOT_DIRTY &&
 250                             collect_one_slot(kip, i))
 251                                 break;
 252                 }
 253         }
 254         c->nr_garbage = 0;
 255         return 0;
 256 }
 257
 258 static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
 259                                        kprobe_opcode_t *slot, int dirty)
 260 {
 261         struct kprobe_insn_page *kip;
 262
 263         list_for_each_entry(kip, &c->pages, list) {
 264                 long idx = ((long)slot - (long)kip->insns) /
 265                                 (c->insn_size * sizeof(kprobe_opcode_t));
 266                 if (idx >= 0 && idx < slots_per_page(c)) {
 267                         WARN_ON(kip->slot_used[idx] != SLOT_USED);
 268                         if (dirty) {
 269                                 kip->slot_used[idx] = SLOT_DIRTY;
 270                                 kip->ngarbage++;
 271                                 if (++c->nr_garbage > slots_per_page(c))
 272                                         collect_garbage_slots(c);
 273                         } else
 274                                 collect_one_slot(kip, idx);
 275                         return;
 276                 }
 277         }
 278         /* Could not free this slot. */
 279         WARN_ON(1);
 280 }
 281
 282 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
 283 {
 284         mutex_lock(&kprobe_insn_mutex);
 285         __free_insn_slot(&kprobe_insn_slots, slot, dirty);
 286         mutex_unlock(&kprobe_insn_mutex);
 287 }
 288 #ifdef CONFIG_OPTPROBES
 289 /* For optimized_kprobe buffer */
 290 static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
 291 static struct kprobe_insn_cache kprobe_optinsn_slots = {
 292         .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
 293         /* .insn_size is initialized later */
 294         .nr_garbage = 0,
 295 };
 296 /* Get a slot for optimized_kprobe buffer */
 297 kprobe_opcode_t __kprobes *get_optinsn_slot(void)
 298 {
 299         kprobe_opcode_t *ret = NULL;
 300
 301         mutex_lock(&kprobe_optinsn_mutex);
 302         ret = __get_insn_slot(&kprobe_optinsn_slots);
 303         mutex_unlock(&kprobe_optinsn_mutex);
 304
 305         return ret;
 306 }
 307
 308 void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
 309 {
 310         mutex_lock(&kprobe_optinsn_mutex);
 311         __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
 312         mutex_unlock(&kprobe_optinsn_mutex);
 313 }
 314 #endif
 315 #endif
 316
 317 /* We have preemption disabled.. so it is safe to use __ versions */
 318 static inline void set_kprobe_instance(struct kprobe *kp)
 319 {
 320         __this_cpu_write(kprobe_instance, kp);
 321 }
 322
 323 static inline void reset_kprobe_instance(void)
 324 {
 325         __this_cpu_write(kprobe_instance, NULL);
 326 }
 327
 328 /*
 329  * This routine is called either:
 330  *      - under the kprobe_mutex - during kprobe_[un]register()
 331  *                              OR
 332  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
 333  */
 334 struct kprobe __kprobes *get_kprobe(void *addr)
 335 {
 336         struct hlist_head *head;
 337         struct kprobe *p;
 338
 339         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
 340         hlist_for_each_entry_rcu(p, head, hlist) {
 341                 if (p->addr == addr)
 342                         return p;
 343         }
 344
 345         return NULL;
 346 }
 347
 348 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
 349
 350 /* Return true if the kprobe is an aggregator */
 351 static inline int kprobe_aggrprobe(struct kprobe *p)
 352 {
 353         return p->pre_handler == aggr_pre_handler;
 354 }
 355
 356 /* Return true(!0) if the kprobe is unused */
 357 static inline int kprobe_unused(struct kprobe *p)
 358 {
 359         return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
 360                list_empty(&p->list);
 361 }
 362
 363 /*
 364  * Keep all fields in the kprobe consistent
 365  */
 366 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
 367 {
 368         memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
 369         memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
 370 }
 371
 372 #ifdef CONFIG_OPTPROBES
 373 /* NOTE: change this value only with kprobe_mutex held */
 374 static bool kprobes_allow_optimization;
 375
 376 /*
 377  * Call all pre_handler on the list, but ignores its return value.
 378  * This must be called from arch-dep optimized caller.
 379  */
 380 void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
 381 {
 382         struct kprobe *kp;
 383
 384         list_for_each_entry_rcu(kp, &p->list, list) {
 385                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 386                         set_kprobe_instance(kp);
 387                         kp->pre_handler(kp, regs);
 388                 }
 389                 reset_kprobe_instance();
 390         }
 391 }
 392
 393 /* Free optimized instructions and optimized_kprobe */
 394 static __kprobes void free_aggr_kprobe(struct kprobe *p)
 395 {
 396         struct optimized_kprobe *op;
 397
 398         op = container_of(p, struct optimized_kprobe, kp);
 399         arch_remove_optimized_kprobe(op);
 400         arch_remove_kprobe(p);
 401         kfree(op);
 402 }
 403
 404 /* Return true(!0) if the kprobe is ready for optimization. */
 405 static inline int kprobe_optready(struct kprobe *p)
 406 {
 407         struct optimized_kprobe *op;
 408
 409         if (kprobe_aggrprobe(p)) {
 410                 op = container_of(p, struct optimized_kprobe, kp);
 411                 return arch_prepared_optinsn(&op->optinsn);
 412         }
 413
 414         return 0;
 415 }
 416
 417 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
 418 static inline int kprobe_disarmed(struct kprobe *p)
 419 {
 420         struct optimized_kprobe *op;
 421
 422         /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
 423         if (!kprobe_aggrprobe(p))
 424                 return kprobe_disabled(p);
 425
 426         op = container_of(p, struct optimized_kprobe, kp);
 427
 428         return kprobe_disabled(p) && list_empty(&op->list);
 429 }
 430
 431 /* Return true(!0) if the probe is queued on (un)optimizing lists */
 432 static int __kprobes kprobe_queued(struct kprobe *p)
 433 {
 434         struct optimized_kprobe *op;
 435
 436         if (kprobe_aggrprobe(p)) {
 437                 op = container_of(p, struct optimized_kprobe, kp);
 438                 if (!list_empty(&op->list))
 439                         return 1;
 440         }
 441         return 0;
 442 }
 443
 444 /*
 445  * Return an optimized kprobe whose optimizing code replaces
 446  * instructions including addr (exclude breakpoint).
 447  */
 448 static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
 449 {
 450         int i;
 451         struct kprobe *p = NULL;
 452         struct optimized_kprobe *op;
 453
 454         /* Don't check i == 0, since that is a breakpoint case. */
 455         for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
 456                 p = get_kprobe((void *)(addr - i));
 457
 458         if (p && kprobe_optready(p)) {
 459                 op = container_of(p, struct optimized_kprobe, kp);
 460                 if (arch_within_optimized_kprobe(op, addr))
 461                         return p;
 462         }
 463
 464         return NULL;
 465 }
 466
 467 /* Optimization staging list, protected by kprobe_mutex */
 468 static LIST_HEAD(optimizing_list);
 469 static LIST_HEAD(unoptimizing_list);
 470
 471 static void kprobe_optimizer(struct work_struct *work);
 472 static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
 473 #define OPTIMIZE_DELAY 5
 474
 475 /*
 476  * Optimize (replace a breakpoint with a jump) kprobes listed on
 477  * optimizing_list.
 478  */
 479 static __kprobes void do_optimize_kprobes(void)
 480 {
 481         /* Optimization never be done when disarmed */
 482         if (kprobes_all_disarmed || !kprobes_allow_optimization ||
 483             list_empty(&optimizing_list))
 484                 return;
 485
 486         /*
 487          * The optimization/unoptimization refers online_cpus via
 488          * stop_machine() and cpu-hotplug modifies online_cpus.
 489          * And same time, text_mutex will be held in cpu-hotplug and here.
 490          * This combination can cause a deadlock (cpu-hotplug try to lock
 491          * text_mutex but stop_machine can not be done because online_cpus
 492          * has been changed)
 493          * To avoid this deadlock, we need to call get_online_cpus()
 494          * for preventing cpu-hotplug outside of text_mutex locking.
 495          */
 496         get_online_cpus();
 497         mutex_lock(&text_mutex);
 498         arch_optimize_kprobes(&optimizing_list);
 499         mutex_unlock(&text_mutex);
 500         put_online_cpus();
 501 }
 502
 503 /*
 504  * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
 505  * if need) kprobes listed on unoptimizing_list.
 506  */
 507 static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
 508 {
 509         struct optimized_kprobe *op, *tmp;
 510
 511         /* Unoptimization must be done anytime */
 512         if (list_empty(&unoptimizing_list))
 513                 return;
 514
 515         /* Ditto to do_optimize_kprobes */
 516         get_online_cpus();
 517         mutex_lock(&text_mutex);
 518         arch_unoptimize_kprobes(&unoptimizing_list, free_list);
 519         /* Loop free_list for disarming */
 520         list_for_each_entry_safe(op, tmp, free_list, list) {
 521                 /* Disarm probes if marked disabled */
 522                 if (kprobe_disabled(&op->kp))
 523                         arch_disarm_kprobe(&op->kp);
 524                 if (kprobe_unused(&op->kp)) {
 525                         /*
 526                          * Remove unused probes from hash list. After waiting
 527                          * for synchronization, these probes are reclaimed.
 528                          * (reclaiming is done by do_free_cleaned_kprobes.)
 529                          */
 530                         hlist_del_rcu(&op->kp.hlist);
 531                 } else
 532                         list_del_init(&op->list);
 533         }
 534         mutex_unlock(&text_mutex);
 535         put_online_cpus();
 536 }
 537
 538 /* Reclaim all kprobes on the free_list */
 539 static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list)
 540 {
 541         struct optimized_kprobe *op, *tmp;
 542
 543         list_for_each_entry_safe(op, tmp, free_list, list) {
 544                 BUG_ON(!kprobe_unused(&op->kp));
 545                 list_del_init(&op->list);
 546                 free_aggr_kprobe(&op->kp);
 547         }
 548 }
 549
 550 /* Start optimizer after OPTIMIZE_DELAY passed */
 551 static __kprobes void kick_kprobe_optimizer(void)
 552 {
 553         schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
 554 }
 555
 556 /* Kprobe jump optimizer */
 557 static __kprobes void kprobe_optimizer(struct work_struct *work)
 558 {
 559         LIST_HEAD(free_list);
 560
 561         mutex_lock(&kprobe_mutex);
 562         /* Lock modules while optimizing kprobes */
 563         mutex_lock(&module_mutex);
 564
 565         /*
 566          * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
 567          * kprobes before waiting for quiesence period.
 568          */
 569         do_unoptimize_kprobes(&free_list);
 570
 571         /*
 572          * Step 2: Wait for quiesence period to ensure all running interrupts
 573          * are done. Because optprobe may modify multiple instructions
 574          * there is a chance that Nth instruction is interrupted. In that
 575          * case, running interrupt can return to 2nd-Nth byte of jump
 576          * instruction. This wait is for avoiding it.
 577          */
 578         synchronize_sched();
 579
 580         /* Step 3: Optimize kprobes after quiesence period */
 581         do_optimize_kprobes();
 582
 583         /* Step 4: Free cleaned kprobes after quiesence period */
 584         do_free_cleaned_kprobes(&free_list);
 585
 586         mutex_unlock(&module_mutex);
 587         mutex_unlock(&kprobe_mutex);
 588
 589         /* Step 5: Kick optimizer again if needed */
 590         if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
 591                 kick_kprobe_optimizer();
 592 }
 593
 594 /* Wait for completing optimization and unoptimization */
 595 static __kprobes void wait_for_kprobe_optimizer(void)
 596 {
 597         mutex_lock(&kprobe_mutex);
 598
 599         while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
 600                 mutex_unlock(&kprobe_mutex);
 601
 602                 /* this will also make optimizing_work execute immmediately */
 603                 flush_delayed_work(&optimizing_work);
 604                 /* @optimizing_work might not have been queued yet, relax */
 605                 cpu_relax();
 606
 607                 mutex_lock(&kprobe_mutex);
 608         }
 609
 610         mutex_unlock(&kprobe_mutex);
 611 }
 612
 613 /* Optimize kprobe if p is ready to be optimized */
 614 static __kprobes void optimize_kprobe(struct kprobe *p)
 615 {
 616         struct optimized_kprobe *op;
 617
 618         /* Check if the kprobe is disabled or not ready for optimization. */
 619         if (!kprobe_optready(p) || !kprobes_allow_optimization ||
 620             (kprobe_disabled(p) || kprobes_all_disarmed))
 621                 return;
 622
 623         /* Both of break_handler and post_handler are not supported. */
 624         if (p->break_handler || p->post_handler)
 625                 return;
 626
 627         op = container_of(p, struct optimized_kprobe, kp);
 628
 629         /* Check there is no other kprobes at the optimized instructions */
 630         if (arch_check_optimized_kprobe(op) < 0)
 631                 return;
 632
 633         /* Check if it is already optimized. */
 634         if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
 635                 return;
 636         op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
 637
 638         if (!list_empty(&op->list))
 639                 /* This is under unoptimizing. Just dequeue the probe */
 640                 list_del_init(&op->list);
 641         else {
 642                 list_add(&op->list, &optimizing_list);
 643                 kick_kprobe_optimizer();
 644         }
 645 }
 646
 647 /* Short cut to direct unoptimizing */
 648 static __kprobes void force_unoptimize_kprobe(struct optimized_kprobe *op)
 649 {
 650         get_online_cpus();
 651         arch_unoptimize_kprobe(op);
 652         put_online_cpus();
 653         if (kprobe_disabled(&op->kp))
 654                 arch_disarm_kprobe(&op->kp);
 655 }
 656
 657 /* Unoptimize a kprobe if p is optimized */
 658 static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force)
 659 {
 660         struct optimized_kprobe *op;
 661
 662         if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
 663                 return; /* This is not an optprobe nor optimized */
 664
 665         op = container_of(p, struct optimized_kprobe, kp);
 666         if (!kprobe_optimized(p)) {
 667                 /* Unoptimized or unoptimizing case */
 668                 if (force && !list_empty(&op->list)) {
 669                         /*
 670                          * Only if this is unoptimizing kprobe and forced,
 671                          * forcibly unoptimize it. (No need to unoptimize
 672                          * unoptimized kprobe again :)
 673                          */
 674                         list_del_init(&op->list);
 675                         force_unoptimize_kprobe(op);
 676                 }
 677                 return;
 678         }
 679
 680         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 681         if (!list_empty(&op->list)) {
 682                 /* Dequeue from the optimization queue */
 683                 list_del_init(&op->list);
 684                 return;
 685         }
 686         /* Optimized kprobe case */
 687         if (force)
 688                 /* Forcibly update the code: this is a special case */
 689                 force_unoptimize_kprobe(op);
 690         else {
 691                 list_add(&op->list, &unoptimizing_list);
 692                 kick_kprobe_optimizer();
 693         }
 694 }
 695
 696 /* Cancel unoptimizing for reusing */
 697 static void reuse_unused_kprobe(struct kprobe *ap)
 698 {
 699         struct optimized_kprobe *op;
 700
 701         BUG_ON(!kprobe_unused(ap));
 702         /*
 703          * Unused kprobe MUST be on the way of delayed unoptimizing (means
 704          * there is still a relative jump) and disabled.
 705          */
 706         op = container_of(ap, struct optimized_kprobe, kp);
 707         if (unlikely(list_empty(&op->list)))
 708                 printk(KERN_WARNING "Warning: found a stray unused "
 709                         "aggrprobe@%p\n", ap->addr);
 710         /* Enable the probe again */
 711         ap->flags &= ~KPROBE_FLAG_DISABLED;
 712         /* Optimize it again (remove from op->list) */
 713         BUG_ON(!kprobe_optready(ap));
 714         optimize_kprobe(ap);
 715 }
 716
 717 /* Remove optimized instructions */
 718 static void __kprobes kill_optimized_kprobe(struct kprobe *p)
 719 {
 720         struct optimized_kprobe *op;
 721
 722         op = container_of(p, struct optimized_kprobe, kp);
 723         if (!list_empty(&op->list))
 724                 /* Dequeue from the (un)optimization queue */
 725                 list_del_init(&op->list);
 726
 727         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 728         /* Don't touch the code, because it is already freed. */
 729         arch_remove_optimized_kprobe(op);
 730 }
 731
 732 /* Try to prepare optimized instructions */
 733 static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
 734 {
 735         struct optimized_kprobe *op;
 736
 737         op = container_of(p, struct optimized_kprobe, kp);
 738         arch_prepare_optimized_kprobe(op);
 739 }
 740
 741 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
 742 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 743 {
 744         struct optimized_kprobe *op;
 745
 746         op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
 747         if (!op)
 748                 return NULL;
 749
 750         INIT_LIST_HEAD(&op->list);
 751         op->kp.addr = p->addr;
 752         arch_prepare_optimized_kprobe(op);
 753
 754         return &op->kp;
 755 }
 756
 757 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
 758
 759 /*
 760  * Prepare an optimized_kprobe and optimize it
 761  * NOTE: p must be a normal registered kprobe
 762  */
 763 static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
 764 {
 765         struct kprobe *ap;
 766         struct optimized_kprobe *op;
 767
 768         /* Impossible to optimize ftrace-based kprobe */
 769         if (kprobe_ftrace(p))
 770                 return;
 771
 772         /* For preparing optimization, jump_label_text_reserved() is called */
 773         jump_label_lock();
 774         mutex_lock(&text_mutex);
 775
 776         ap = alloc_aggr_kprobe(p);
 777         if (!ap)
 778                 goto out;
 779
 780         op = container_of(ap, struct optimized_kprobe, kp);
 781         if (!arch_prepared_optinsn(&op->optinsn)) {
 782                 /* If failed to setup optimizing, fallback to kprobe */
 783                 arch_remove_optimized_kprobe(op);
 784                 kfree(op);
 785                 goto out;
 786         }
 787
 788         init_aggr_kprobe(ap, p);
 789         optimize_kprobe(ap);    /* This just kicks optimizer thread */
 790
 791 out:
 792         mutex_unlock(&text_mutex);
 793         jump_label_unlock();
 794 }
 795
 796 #ifdef CONFIG_SYSCTL
 797 static void __kprobes optimize_all_kprobes(void)
 798 {
 799         struct hlist_head *head;
 800         struct kprobe *p;
 801         unsigned int i;
 802
 803         mutex_lock(&kprobe_mutex);
 804         /* If optimization is already allowed, just return */
 805         if (kprobes_allow_optimization)
 806                 goto out;
 807
 808         kprobes_allow_optimization = true;
 809         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 810                 head = &kprobe_table[i];
 811                 hlist_for_each_entry_rcu(p, head, hlist)
 812                         if (!kprobe_disabled(p))
 813                                 optimize_kprobe(p);
 814         }
 815         printk(KERN_INFO "Kprobes globally optimized\n");
 816 out:
 817         mutex_unlock(&kprobe_mutex);
 818 }
 819
 820 static void __kprobes unoptimize_all_kprobes(void)
 821 {
 822         struct hlist_head *head;
 823         struct kprobe *p;
 824         unsigned int i;
 825
 826         mutex_lock(&kprobe_mutex);
 827         /* If optimization is already prohibited, just return */
 828         if (!kprobes_allow_optimization) {
 829                 mutex_unlock(&kprobe_mutex);
 830                 return;
 831         }
 832
 833         kprobes_allow_optimization = false;
 834         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 835                 head = &kprobe_table[i];
 836                 hlist_for_each_entry_rcu(p, head, hlist) {
 837                         if (!kprobe_disabled(p))
 838                                 unoptimize_kprobe(p, false);
 839                 }
 840         }
 841         mutex_unlock(&kprobe_mutex);
 842
 843         /* Wait for unoptimizing completion */
 844         wait_for_kprobe_optimizer();
 845         printk(KERN_INFO "Kprobes globally unoptimized\n");
 846 }
 847
 848 static DEFINE_MUTEX(kprobe_sysctl_mutex);
 849 int sysctl_kprobes_optimization;
 850 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
 851                                       void __user *buffer, size_t *length,
 852                                       loff_t *ppos)
 853 {
 854         int ret;
 855
 856         mutex_lock(&kprobe_sysctl_mutex);
 857         sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
 858         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
 859
 860         if (sysctl_kprobes_optimization)
 861                 optimize_all_kprobes();
 862         else
 863                 unoptimize_all_kprobes();
 864         mutex_unlock(&kprobe_sysctl_mutex);
 865
 866         return ret;
 867 }
 868 #endif /* CONFIG_SYSCTL */
 869
 870 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
 871 static void __kprobes __arm_kprobe(struct kprobe *p)
 872 {
 873         struct kprobe *_p;
 874
 875         /* Check collision with other optimized kprobes */
 876         _p = get_optimized_kprobe((unsigned long)p->addr);
 877         if (unlikely(_p))
 878                 /* Fallback to unoptimized kprobe */
 879                 unoptimize_kprobe(_p, true);
 880
 881         arch_arm_kprobe(p);
 882         optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
 883 }
 884
 885 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
 886 static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt)
 887 {
 888         struct kprobe *_p;
 889
 890         unoptimize_kprobe(p, false);    /* Try to unoptimize */
 891
 892         if (!kprobe_queued(p)) {
 893                 arch_disarm_kprobe(p);
 894                 /* If another kprobe was blocked, optimize it. */
 895                 _p = get_optimized_kprobe((unsigned long)p->addr);
 896                 if (unlikely(_p) && reopt)
 897                         optimize_kprobe(_p);
 898         }
 899         /* TODO: reoptimize others after unoptimized this probe */
 900 }
 901
 902 #else /* !CONFIG_OPTPROBES */
 903
 904 #define optimize_kprobe(p)                      do {} while (0)
 905 #define unoptimize_kprobe(p, f)                 do {} while (0)
 906 #define kill_optimized_kprobe(p)                do {} while (0)
 907 #define prepare_optimized_kprobe(p)             do {} while (0)
 908 #define try_to_optimize_kprobe(p)               do {} while (0)
 909 #define __arm_kprobe(p)                         arch_arm_kprobe(p)
 910 #define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
 911 #define kprobe_disarmed(p)                      kprobe_disabled(p)
 912 #define wait_for_kprobe_optimizer()             do {} while (0)
 913
 914 /* There should be no unused kprobes can be reused without optimization */
 915 static void reuse_unused_kprobe(struct kprobe *ap)
 916 {
 917         printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
 918         BUG_ON(kprobe_unused(ap));
 919 }
 920
 921 static __kprobes void free_aggr_kprobe(struct kprobe *p)
 922 {
 923         arch_remove_kprobe(p);
 924         kfree(p);
 925 }
 926
 927 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 928 {
 929         return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
 930 }
 931 #endif /* CONFIG_OPTPROBES */
 932
 933 #ifdef CONFIG_KPROBES_ON_FTRACE
 934 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
 935         .func = kprobe_ftrace_handler,
 936         .flags = FTRACE_OPS_FL_SAVE_REGS,
 937 };
 938 static int kprobe_ftrace_enabled;
 939
 940 /* Must ensure p->addr is really on ftrace */
 941 static int __kprobes prepare_kprobe(struct kprobe *p)
 942 {
 943         if (!kprobe_ftrace(p))
 944                 return arch_prepare_kprobe(p);
 945
 946         return arch_prepare_kprobe_ftrace(p);
 947 }
 948
 949 /* Caller must lock kprobe_mutex */
 950 static void __kprobes arm_kprobe_ftrace(struct kprobe *p)
 951 {
 952         int ret;
 953
 954         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 955                                    (unsigned long)p->addr, 0, 0);
 956         WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 957         kprobe_ftrace_enabled++;
 958         if (kprobe_ftrace_enabled == 1) {
 959                 ret = register_ftrace_function(&kprobe_ftrace_ops);
 960                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 961         }
 962 }
 963
 964 /* Caller must lock kprobe_mutex */
 965 static void __kprobes disarm_kprobe_ftrace(struct kprobe *p)
 966 {
 967         int ret;
 968
 969         kprobe_ftrace_enabled--;
 970         if (kprobe_ftrace_enabled == 0) {
 971                 ret = unregister_ftrace_function(&kprobe_ftrace_ops);
 972                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 973         }
 974         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 975                            (unsigned long)p->addr, 1, 0);
 976         WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 977 }
 978 #else   /* !CONFIG_KPROBES_ON_FTRACE */
 979 #define prepare_kprobe(p)       arch_prepare_kprobe(p)
 980 #define arm_kprobe_ftrace(p)    do {} while (0)
 981 #define disarm_kprobe_ftrace(p) do {} while (0)
 982 #endif
 983
 984 /* Arm a kprobe with text_mutex */
 985 static void __kprobes arm_kprobe(struct kprobe *kp)
 986 {
 987         if (unlikely(kprobe_ftrace(kp))) {
 988                 arm_kprobe_ftrace(kp);
 989                 return;
 990         }
 991         /*
 992          * Here, since __arm_kprobe() doesn't use stop_machine(),
 993          * this doesn't cause deadlock on text_mutex. So, we don't
 994          * need get_online_cpus().
 995          */
 996         mutex_lock(&text_mutex);
 997         __arm_kprobe(kp);
 998         mutex_unlock(&text_mutex);
 999 }
1000
1001 /* Disarm a kprobe with text_mutex */
1002 static void __kprobes disarm_kprobe(struct kprobe *kp, bool reopt)
1003 {
1004         if (unlikely(kprobe_ftrace(kp))) {
1005                 disarm_kprobe_ftrace(kp);
1006                 return;
1007         }
1008         /* Ditto */
1009         mutex_lock(&text_mutex);
1010         __disarm_kprobe(kp, reopt);
1011         mutex_unlock(&text_mutex);
1012 }
1013
1014 /*
1015  * Aggregate handlers for multiple kprobes support - these handlers
1016  * take care of invoking the individual kprobe handlers on p->list
1017  */
1018 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1019 {
1020         struct kprobe *kp;
1021
1022         list_for_each_entry_rcu(kp, &p->list, list) {
1023                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1024                         set_kprobe_instance(kp);
1025                         if (kp->pre_handler(kp, regs))
1026                                 return 1;
1027                 }
1028                 reset_kprobe_instance();
1029         }
1030         return 0;
1031 }
1032
1033 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1034                                         unsigned long flags)
1035 {
1036         struct kprobe *kp;
1037
1038         list_for_each_entry_rcu(kp, &p->list, list) {
1039                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1040                         set_kprobe_instance(kp);
1041                         kp->post_handler(kp, regs, flags);
1042                         reset_kprobe_instance();
1043                 }
1044         }
1045 }
1046
1047 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1048                                         int trapnr)
1049 {
1050         struct kprobe *cur = __this_cpu_read(kprobe_instance);
1051
1052         /*
1053          * if we faulted "during" the execution of a user specified
1054          * probe handler, invoke just that probe's fault handler
1055          */
1056         if (cur && cur->fault_handler) {
1057                 if (cur->fault_handler(cur, regs, trapnr))
1058                         return 1;
1059         }
1060         return 0;
1061 }
1062
1063 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
1064 {
1065         struct kprobe *cur = __this_cpu_read(kprobe_instance);
1066         int ret = 0;
1067
1068         if (cur && cur->break_handler) {
1069                 if (cur->break_handler(cur, regs))
1070                         ret = 1;
1071         }
1072         reset_kprobe_instance();
1073         return ret;
1074 }
1075
1076 /* Walks the list and increments nmissed count for multiprobe case */
1077 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
1078 {
1079         struct kprobe *kp;
1080         if (!kprobe_aggrprobe(p)) {
1081                 p->nmissed++;
1082         } else {
1083                 list_for_each_entry_rcu(kp, &p->list, list)
1084                         kp->nmissed++;
1085         }
1086         return;
1087 }
1088
1089 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
1090                                 struct hlist_head *head)
1091 {
1092         struct kretprobe *rp = ri->rp;
1093
1094         /* remove rp inst off the rprobe_inst_table */
1095         hlist_del(&ri->hlist);
1096         INIT_HLIST_NODE(&ri->hlist);
1097         if (likely(rp)) {
1098                 raw_spin_lock(&rp->lock);
1099                 hlist_add_head(&ri->hlist, &rp->free_instances);
1100                 raw_spin_unlock(&rp->lock);
1101         } else
1102                 /* Unregistering */
1103                 hlist_add_head(&ri->hlist, head);
1104 }
1105
1106 void __kprobes kretprobe_hash_lock(struct task_struct *tsk,
1107                          struct hlist_head **head, unsigned long *flags)
1108 __acquires(hlist_lock)
1109 {
1110         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1111         raw_spinlock_t *hlist_lock;
1112
1113         *head = &kretprobe_inst_table[hash];
1114         hlist_lock = kretprobe_table_lock_ptr(hash);
1115         raw_spin_lock_irqsave(hlist_lock, *flags);
1116 }
1117
1118 static void __kprobes kretprobe_table_lock(unsigned long hash,
1119         unsigned long *flags)
1120 __acquires(hlist_lock)
1121 {
1122         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1123         raw_spin_lock_irqsave(hlist_lock, *flags);
1124 }
1125
1126 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
1127         unsigned long *flags)
1128 __releases(hlist_lock)
1129 {
1130         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1131         raw_spinlock_t *hlist_lock;
1132
1133         hlist_lock = kretprobe_table_lock_ptr(hash);
1134         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1135 }
1136
1137 static void __kprobes kretprobe_table_unlock(unsigned long hash,
1138        unsigned long *flags)
1139 __releases(hlist_lock)
1140 {
1141         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1142         raw_spin_unlock_irqrestore(hlist_lock, *flags);
1143 }
1144
1145 /*
1146  * This function is called from finish_task_switch when task tk becomes dead,
1147  * so that we can recycle any function-return probe instances associated
1148  * with this task. These left over instances represent probed functions
1149  * that have been called but will never return.
1150  */
1151 void __kprobes kprobe_flush_task(struct task_struct *tk)
1152 {
1153         struct kretprobe_instance *ri;
1154         struct hlist_head *head, empty_rp;
1155         struct hlist_node *tmp;
1156         unsigned long hash, flags = 0;
1157
1158         if (unlikely(!kprobes_initialized))
1159                 /* Early boot.  kretprobe_table_locks not yet initialized. */
1160                 return;
1161
1162         INIT_HLIST_HEAD(&empty_rp);
1163         hash = hash_ptr(tk, KPROBE_HASH_BITS);
1164         head = &kretprobe_inst_table[hash];
1165         kretprobe_table_lock(hash, &flags);
1166         hlist_for_each_entry_safe(ri, tmp, head, hlist) {
1167                 if (ri->task == tk)
1168                         recycle_rp_inst(ri, &empty_rp);
1169         }
1170         kretprobe_table_unlock(hash, &flags);
1171         hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
1172                 hlist_del(&ri->hlist);
1173                 kfree(ri);
1174         }
1175 }
1176
1177 static inline void free_rp_inst(struct kretprobe *rp)
1178 {
1179         struct kretprobe_instance *ri;
1180         struct hlist_node *next;
1181
1182         hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1183                 hlist_del(&ri->hlist);
1184                 kfree(ri);
1185         }
1186 }
1187
1188 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
1189 {
1190         unsigned long flags, hash;
1191         struct kretprobe_instance *ri;
1192         struct hlist_node *next;
1193         struct hlist_head *head;
1194
1195         /* No race here */
1196         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1197                 kretprobe_table_lock(hash, &flags);
1198                 head = &kretprobe_inst_table[hash];
1199                 hlist_for_each_entry_safe(ri, next, head, hlist) {
1200                         if (ri->rp == rp)
1201                                 ri->rp = NULL;
1202                 }
1203                 kretprobe_table_unlock(hash, &flags);
1204         }
1205         free_rp_inst(rp);
1206 }
1207
1208 /*
1209 * Add the new probe to ap->list. Fail if this is the
1210 * second jprobe at the address - two jprobes can't coexist
1211 */
1212 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1213 {
1214         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1215
1216         if (p->break_handler || p->post_handler)
1217                 unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1218
1219         if (p->break_handler) {
1220                 if (ap->break_handler)
1221                         return -EEXIST;
1222                 list_add_tail_rcu(&p->list, &ap->list);
1223                 ap->break_handler = aggr_break_handler;
1224         } else
1225                 list_add_rcu(&p->list, &ap->list);
1226         if (p->post_handler && !ap->post_handler)
1227                 ap->post_handler = aggr_post_handler;
1228
1229         return 0;
1230 }
1231
1232 /*
1233  * Fill in the required fields of the "manager kprobe". Replace the
1234  * earlier kprobe in the hlist with the manager kprobe
1235  */
1236 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1237 {
1238         /* Copy p's insn slot to ap */
1239         copy_kprobe(p, ap);
1240         flush_insn_slot(ap);
1241         ap->addr = p->addr;
1242         ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1243         ap->pre_handler = aggr_pre_handler;
1244         ap->fault_handler = aggr_fault_handler;
1245         /* We don't care the kprobe which has gone. */
1246         if (p->post_handler && !kprobe_gone(p))
1247                 ap->post_handler = aggr_post_handler;
1248         if (p->break_handler && !kprobe_gone(p))
1249                 ap->break_handler = aggr_break_handler;
1250
1251         INIT_LIST_HEAD(&ap->list);
1252         INIT_HLIST_NODE(&ap->hlist);
1253
1254         list_add_rcu(&p->list, &ap->list);
1255         hlist_replace_rcu(&p->hlist, &ap->hlist);
1256 }
1257
1258 /*
1259  * This is the second or subsequent kprobe at the address - handle
1260  * the intricacies
1261  */
1262 static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
1263                                           struct kprobe *p)
1264 {
1265         int ret = 0;
1266         struct kprobe *ap = orig_p;
1267
1268         /* For preparing optimization, jump_label_text_reserved() is called */
1269         jump_label_lock();
1270         /*
1271          * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1272          * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1273          */
1274         get_online_cpus();
1275         mutex_lock(&text_mutex);
1276
1277         if (!kprobe_aggrprobe(orig_p)) {
1278                 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1279                 ap = alloc_aggr_kprobe(orig_p);
1280                 if (!ap) {
1281                         ret = -ENOMEM;
1282                         goto out;
1283                 }
1284                 init_aggr_kprobe(ap, orig_p);
1285         } else if (kprobe_unused(ap))
1286                 /* This probe is going to die. Rescue it */
1287                 reuse_unused_kprobe(ap);
1288
1289         if (kprobe_gone(ap)) {
1290                 /*
1291                  * Attempting to insert new probe at the same location that
1292                  * had a probe in the module vaddr area which already
1293                  * freed. So, the instruction slot has already been
1294                  * released. We need a new slot for the new probe.
1295                  */
1296                 ret = arch_prepare_kprobe(ap);
1297                 if (ret)
1298                         /*
1299                          * Even if fail to allocate new slot, don't need to
1300                          * free aggr_probe. It will be used next time, or
1301                          * freed by unregister_kprobe.
1302                          */
1303                         goto out;
1304
1305                 /* Prepare optimized instructions if possible. */
1306                 prepare_optimized_kprobe(ap);
1307
1308                 /*
1309                  * Clear gone flag to prevent allocating new slot again, and
1310                  * set disabled flag because it is not armed yet.
1311                  */
1312                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1313                             | KPROBE_FLAG_DISABLED;
1314         }
1315
1316         /* Copy ap's insn slot to p */
1317         copy_kprobe(ap, p);
1318         ret = add_new_kprobe(ap, p);
1319
1320 out:
1321         mutex_unlock(&text_mutex);
1322         put_online_cpus();
1323         jump_label_unlock();
1324
1325         if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1326                 ap->flags &= ~KPROBE_FLAG_DISABLED;
1327                 if (!kprobes_all_disarmed)
1328                         /* Arm the breakpoint again. */
1329                         arm_kprobe(ap);
1330         }
1331         return ret;
1332 }
1333
1334 static int __kprobes in_kprobes_functions(unsigned long addr)
1335 {
1336         struct kprobe_blackpoint *kb;
1337
1338         if (addr >= (unsigned long)__kprobes_text_start &&
1339             addr < (unsigned long)__kprobes_text_end)
1340                 return -EINVAL;
1341         /*
1342          * If there exists a kprobe_blacklist, verify and
1343          * fail any probe registration in the prohibited area
1344          */
1345         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
1346                 if (kb->start_addr) {
1347                         if (addr >= kb->start_addr &&
1348                             addr < (kb->start_addr + kb->range))
1349                                 return -EINVAL;
1350                 }
1351         }
1352         return 0;
1353 }
1354
1355 /*
1356  * If we have a symbol_name argument, look it up and add the offset field
1357  * to it. This way, we can specify a relative address to a symbol.
1358  * This returns encoded errors if it fails to look up symbol or invalid
1359  * combination of parameters.
1360  */
1361 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
1362 {
1363         kprobe_opcode_t *addr = p->addr;
1364
1365         if ((p->symbol_name && p->addr) ||
1366             (!p->symbol_name && !p->addr))
1367                 goto invalid;
1368
1369         if (p->symbol_name) {
1370                 kprobe_lookup_name(p->symbol_name, addr);
1371                 if (!addr)
1372                         return ERR_PTR(-ENOENT);
1373         }
1374
1375         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1376         if (addr)
1377                 return addr;
1378
1379 invalid:
1380         return ERR_PTR(-EINVAL);
1381 }
1382
1383 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1384 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
1385 {
1386         struct kprobe *ap, *list_p;
1387
1388         ap = get_kprobe(p->addr);
1389         if (unlikely(!ap))
1390                 return NULL;
1391
1392         if (p != ap) {
1393                 list_for_each_entry_rcu(list_p, &ap->list, list)
1394                         if (list_p == p)
1395                         /* kprobe p is a valid probe */
1396                                 goto valid;
1397                 return NULL;
1398         }
1399 valid:
1400         return ap;
1401 }
1402
1403 /* Return error if the kprobe is being re-registered */
1404 static inline int check_kprobe_rereg(struct kprobe *p)
1405 {
1406         int ret = 0;
1407
1408         mutex_lock(&kprobe_mutex);
1409         if (__get_valid_kprobe(p))
1410                 ret = -EINVAL;
1411         mutex_unlock(&kprobe_mutex);
1412
1413         return ret;
1414 }
1415
1416 static __kprobes int check_kprobe_address_safe(struct kprobe *p,
1417                                                struct module **probed_mod)
1418 {
1419         int ret = 0;
1420         unsigned long ftrace_addr;
1421
1422         /*
1423          * If the address is located on a ftrace nop, set the
1424          * breakpoint to the following instruction.
1425          */
1426         ftrace_addr = ftrace_location((unsigned long)p->addr);
1427         if (ftrace_addr) {
1428 #ifdef CONFIG_KPROBES_ON_FTRACE
1429                 /* Given address is not on the instruction boundary */
1430                 if ((unsigned long)p->addr != ftrace_addr)
1431                         return -EILSEQ;
1432                 p->flags |= KPROBE_FLAG_FTRACE;
1433 #else   /* !CONFIG_KPROBES_ON_FTRACE */
1434                 return -EINVAL;
1435 #endif
1436         }
1437
1438         jump_label_lock();
1439         preempt_disable();
1440
1441         /* Ensure it is not in reserved area nor out of text */
1442         if (!kernel_text_address((unsigned long) p->addr) ||
1443             in_kprobes_functions((unsigned long) p->addr) ||
1444             jump_label_text_reserved(p->addr, p->addr)) {
1445                 ret = -EINVAL;
1446                 goto out;
1447         }
1448
1449         /* Check if are we probing a module */
1450         *probed_mod = __module_text_address((unsigned long) p->addr);
1451         if (*probed_mod) {
1452                 /*
1453                  * We must hold a refcount of the probed module while updating
1454                  * its code to prohibit unexpected unloading.
1455                  */
1456                 if (unlikely(!try_module_get(*probed_mod))) {
1457                         ret = -ENOENT;
1458                         goto out;
1459                 }
1460
1461                 /*
1462                  * If the module freed .init.text, we couldn't insert
1463                  * kprobes in there.
1464                  */
1465                 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1466                     (*probed_mod)->state != MODULE_STATE_COMING) {
1467                         module_put(*probed_mod);
1468                         *probed_mod = NULL;
1469                         ret = -ENOENT;
1470                 }
1471         }
1472 out:
1473         preempt_enable();
1474         jump_label_unlock();
1475
1476         return ret;
1477 }
1478
1479 int __kprobes register_kprobe(struct kprobe *p)
1480 {
1481         int ret;
1482         struct kprobe *old_p;
1483         struct module *probed_mod;
1484         kprobe_opcode_t *addr;
1485
1486         /* Adjust probe address from symbol */
1487         addr = kprobe_addr(p);
1488         if (IS_ERR(addr))
1489                 return PTR_ERR(addr);
1490         p->addr = addr;
1491
1492         ret = check_kprobe_rereg(p);
1493         if (ret)
1494                 return ret;
1495
1496         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1497         p->flags &= KPROBE_FLAG_DISABLED;
1498         p->nmissed = 0;
1499         INIT_LIST_HEAD(&p->list);
1500
1501         ret = check_kprobe_address_safe(p, &probed_mod);
1502         if (ret)
1503                 return ret;
1504
1505         mutex_lock(&kprobe_mutex);
1506
1507         old_p = get_kprobe(p->addr);
1508         if (old_p) {
1509                 /* Since this may unoptimize old_p, locking text_mutex. */
1510                 ret = register_aggr_kprobe(old_p, p);
1511                 goto out;
1512         }
1513
1514         mutex_lock(&text_mutex);        /* Avoiding text modification */
1515         ret = prepare_kprobe(p);
1516         mutex_unlock(&text_mutex);
1517         if (ret)
1518                 goto out;
1519
1520         INIT_HLIST_NODE(&p->hlist);
1521         hlist_add_head_rcu(&p->hlist,
1522                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1523
1524         if (!kprobes_all_disarmed && !kprobe_disabled(p))
1525                 arm_kprobe(p);
1526
1527         /* Try to optimize kprobe */
1528         try_to_optimize_kprobe(p);
1529
1530 out:
1531         mutex_unlock(&kprobe_mutex);
1532
1533         if (probed_mod)
1534                 module_put(probed_mod);
1535
1536         return ret;
1537 }
1538 EXPORT_SYMBOL_GPL(register_kprobe);
1539
1540 /* Check if all probes on the aggrprobe are disabled */
1541 static int __kprobes aggr_kprobe_disabled(struct kprobe *ap)
1542 {
1543         struct kprobe *kp;
1544
1545         list_for_each_entry_rcu(kp, &ap->list, list)
1546                 if (!kprobe_disabled(kp))
1547                         /*
1548                          * There is an active probe on the list.
1549                          * We can't disable this ap.
1550                          */
1551                         return 0;
1552
1553         return 1;
1554 }
1555
1556 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1557 static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
1558 {
1559         struct kprobe *orig_p;
1560
1561         /* Get an original kprobe for return */
1562         orig_p = __get_valid_kprobe(p);
1563         if (unlikely(orig_p == NULL))
1564                 return NULL;
1565
1566         if (!kprobe_disabled(p)) {
1567                 /* Disable probe if it is a child probe */
1568                 if (p != orig_p)
1569                         p->flags |= KPROBE_FLAG_DISABLED;
1570
1571                 /* Try to disarm and disable this/parent probe */
1572                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1573                         disarm_kprobe(orig_p, true);
1574                         orig_p->flags |= KPROBE_FLAG_DISABLED;
1575                 }
1576         }
1577
1578         return orig_p;
1579 }
1580
1581 /*
1582  * Unregister a kprobe without a scheduler synchronization.
1583  */
1584 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
1585 {
1586         struct kprobe *ap, *list_p;
1587
1588         /* Disable kprobe. This will disarm it if needed. */
1589         ap = __disable_kprobe(p);
1590         if (ap == NULL)
1591                 return -EINVAL;
1592
1593         if (ap == p)
1594                 /*
1595                  * This probe is an independent(and non-optimized) kprobe
1596                  * (not an aggrprobe). Remove from the hash list.
1597                  */
1598                 goto disarmed;
1599
1600         /* Following process expects this probe is an aggrprobe */
1601         WARN_ON(!kprobe_aggrprobe(ap));
1602
1603         if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1604                 /*
1605                  * !disarmed could be happen if the probe is under delayed
1606                  * unoptimizing.
1607                  */
1608                 goto disarmed;
1609         else {
1610                 /* If disabling probe has special handlers, update aggrprobe */
1611                 if (p->break_handler && !kprobe_gone(p))
1612                         ap->break_handler = NULL;
1613                 if (p->post_handler && !kprobe_gone(p)) {
1614                         list_for_each_entry_rcu(list_p, &ap->list, list) {
1615                                 if ((list_p != p) && (list_p->post_handler))
1616                                         goto noclean;
1617                         }
1618                         ap->post_handler = NULL;
1619                 }
1620 noclean:
1621                 /*
1622                  * Remove from the aggrprobe: this path will do nothing in
1623                  * __unregister_kprobe_bottom().
1624                  */
1625                 list_del_rcu(&p->list);
1626                 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1627                         /*
1628                          * Try to optimize this probe again, because post
1629                          * handler may have been changed.
1630                          */
1631                         optimize_kprobe(ap);
1632         }
1633         return 0;
1634
1635 disarmed:
1636         BUG_ON(!kprobe_disarmed(ap));
1637         hlist_del_rcu(&ap->hlist);
1638         return 0;
1639 }
1640
1641 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
1642 {
1643         struct kprobe *ap;
1644
1645         if (list_empty(&p->list))
1646                 /* This is an independent kprobe */
1647                 arch_remove_kprobe(p);
1648         else if (list_is_singular(&p->list)) {
1649                 /* This is the last child of an aggrprobe */
1650                 ap = list_entry(p->list.next, struct kprobe, list);
1651                 list_del(&p->list);
1652                 free_aggr_kprobe(ap);
1653         }
1654         /* Otherwise, do nothing. */
1655 }
1656
1657 int __kprobes register_kprobes(struct kprobe **kps, int num)
1658 {
1659         int i, ret = 0;
1660
1661         if (num <= 0)
1662                 return -EINVAL;
1663         for (i = 0; i < num; i++) {
1664                 ret = register_kprobe(kps[i]);
1665                 if (ret < 0) {
1666                         if (i > 0)
1667                                 unregister_kprobes(kps, i);
1668                         break;
1669                 }
1670         }
1671         return ret;
1672 }
1673 EXPORT_SYMBOL_GPL(register_kprobes);
1674
1675 void __kprobes unregister_kprobe(struct kprobe *p)
1676 {
1677         unregister_kprobes(&p, 1);
1678 }
1679 EXPORT_SYMBOL_GPL(unregister_kprobe);
1680
1681 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
1682 {
1683         int i;
1684
1685         if (num <= 0)
1686                 return;
1687         mutex_lock(&kprobe_mutex);
1688         for (i = 0; i < num; i++)
1689                 if (__unregister_kprobe_top(kps[i]) < 0)
1690                         kps[i]->addr = NULL;
1691         mutex_unlock(&kprobe_mutex);
1692
1693         synchronize_sched();
1694         for (i = 0; i < num; i++)
1695                 if (kps[i]->addr)
1696                         __unregister_kprobe_bottom(kps[i]);
1697 }
1698 EXPORT_SYMBOL_GPL(unregister_kprobes);
1699
1700 static struct notifier_block kprobe_exceptions_nb = {
1701         .notifier_call = kprobe_exceptions_notify,
1702         .priority = 0x7fffffff /* we need to be notified first */
1703 };
1704
1705 unsigned long __weak arch_deref_entry_point(void *entry)
1706 {
1707         return (unsigned long)entry;
1708 }
1709
1710 int __kprobes register_jprobes(struct jprobe **jps, int num)
1711 {
1712         struct jprobe *jp;
1713         int ret = 0, i;
1714
1715         if (num <= 0)
1716                 return -EINVAL;
1717         for (i = 0; i < num; i++) {
1718                 unsigned long addr, offset;
1719                 jp = jps[i];
1720                 addr = arch_deref_entry_point(jp->entry);
1721
1722                 /* Verify probepoint is a function entry point */
1723                 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1724                     offset == 0) {
1725                         jp->kp.pre_handler = setjmp_pre_handler;
1726                         jp->kp.break_handler = longjmp_break_handler;
1727                         ret = register_kprobe(&jp->kp);
1728                 } else
1729                         ret = -EINVAL;
1730
1731                 if (ret < 0) {
1732                         if (i > 0)
1733                                 unregister_jprobes(jps, i);
1734                         break;
1735                 }
1736         }
1737         return ret;
1738 }
1739 EXPORT_SYMBOL_GPL(register_jprobes);
1740
1741 int __kprobes register_jprobe(struct jprobe *jp)
1742 {
1743         return register_jprobes(&jp, 1);
1744 }
1745 EXPORT_SYMBOL_GPL(register_jprobe);
1746
1747 void __kprobes unregister_jprobe(struct jprobe *jp)
1748 {
1749         unregister_jprobes(&jp, 1);
1750 }
1751 EXPORT_SYMBOL_GPL(unregister_jprobe);
1752
1753 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
1754 {
1755         int i;
1756
1757         if (num <= 0)
1758                 return;
1759         mutex_lock(&kprobe_mutex);
1760         for (i = 0; i < num; i++)
1761                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1762                         jps[i]->kp.addr = NULL;
1763         mutex_unlock(&kprobe_mutex);
1764
1765         synchronize_sched();
1766         for (i = 0; i < num; i++) {
1767                 if (jps[i]->kp.addr)
1768                         __unregister_kprobe_bottom(&jps[i]->kp);
1769         }
1770 }
1771 EXPORT_SYMBOL_GPL(unregister_jprobes);
1772
1773 #ifdef CONFIG_KRETPROBES
1774 /*
1775  * This kprobe pre_handler is registered with every kretprobe. When probe
1776  * hits it will set up the return probe.
1777  */
1778 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1779                                            struct pt_regs *regs)
1780 {
1781         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1782         unsigned long hash, flags = 0;
1783         struct kretprobe_instance *ri;
1784
1785         /*TODO: consider to only swap the RA after the last pre_handler fired */
1786         hash = hash_ptr(current, KPROBE_HASH_BITS);
1787         raw_spin_lock_irqsave(&rp->lock, flags);
1788         if (!hlist_empty(&rp->free_instances)) {
1789                 ri = hlist_entry(rp->free_instances.first,
1790                                 struct kretprobe_instance, hlist);
1791                 hlist_del(&ri->hlist);
1792                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1793
1794                 ri->rp = rp;
1795                 ri->task = current;
1796
1797                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1798                         raw_spin_lock_irqsave(&rp->lock, flags);
1799                         hlist_add_head(&ri->hlist, &rp->free_instances);
1800                         raw_spin_unlock_irqrestore(&rp->lock, flags);
1801                         return 0;
1802                 }
1803
1804                 arch_prepare_kretprobe(ri, regs);
1805
1806                 /* XXX(hch): why is there no hlist_move_head? */
1807                 INIT_HLIST_NODE(&ri->hlist);
1808                 kretprobe_table_lock(hash, &flags);
1809                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1810                 kretprobe_table_unlock(hash, &flags);
1811         } else {
1812                 rp->nmissed++;
1813                 raw_spin_unlock_irqrestore(&rp->lock, flags);
1814         }
1815         return 0;
1816 }
1817
1818 int __kprobes register_kretprobe(struct kretprobe *rp)
1819 {
1820         int ret = 0;
1821         struct kretprobe_instance *inst;
1822         int i;
1823         void *addr;
1824
1825         if (kretprobe_blacklist_size) {
1826                 addr = kprobe_addr(&rp->kp);
1827                 if (IS_ERR(addr))
1828                         return PTR_ERR(addr);
1829
1830                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1831                         if (kretprobe_blacklist[i].addr == addr)
1832                                 return -EINVAL;
1833                 }
1834         }
1835
1836         rp->kp.pre_handler = pre_handler_kretprobe;
1837         rp->kp.post_handler = NULL;
1838         rp->kp.fault_handler = NULL;
1839         rp->kp.break_handler = NULL;
1840
1841         /* Pre-allocate memory for max kretprobe instances */
1842         if (rp->maxactive <= 0) {
1843 #ifdef CONFIG_PREEMPT
1844                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1845 #else
1846                 rp->maxactive = num_possible_cpus();
1847 #endif
1848         }
1849         raw_spin_lock_init(&rp->lock);
1850         INIT_HLIST_HEAD(&rp->free_instances);
1851         for (i = 0; i < rp->maxactive; i++) {
1852                 inst = kmalloc(sizeof(struct kretprobe_instance) +
1853                                rp->data_size, GFP_KERNEL);
1854                 if (inst == NULL) {
1855                         free_rp_inst(rp);
1856                         return -ENOMEM;
1857                 }
1858                 INIT_HLIST_NODE(&inst->hlist);
1859                 hlist_add_head(&inst->hlist, &rp->free_instances);
1860         }
1861
1862         rp->nmissed = 0;
1863         /* Establish function entry probe point */
1864         ret = register_kprobe(&rp->kp);
1865         if (ret != 0)
1866                 free_rp_inst(rp);
1867         return ret;
1868 }
1869 EXPORT_SYMBOL_GPL(register_kretprobe);
1870
1871 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1872 {
1873         int ret = 0, i;
1874
1875         if (num <= 0)
1876                 return -EINVAL;
1877         for (i = 0; i < num; i++) {
1878                 ret = register_kretprobe(rps[i]);
1879                 if (ret < 0) {
1880                         if (i > 0)
1881                                 unregister_kretprobes(rps, i);
1882                         break;
1883                 }
1884         }
1885         return ret;
1886 }
1887 EXPORT_SYMBOL_GPL(register_kretprobes);
1888
1889 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1890 {
1891         unregister_kretprobes(&rp, 1);
1892 }
1893 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1894
1895 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1896 {
1897         int i;
1898
1899         if (num <= 0)
1900                 return;
1901         mutex_lock(&kprobe_mutex);
1902         for (i = 0; i < num; i++)
1903                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1904                         rps[i]->kp.addr = NULL;
1905         mutex_unlock(&kprobe_mutex);
1906
1907         synchronize_sched();
1908         for (i = 0; i < num; i++) {
1909                 if (rps[i]->kp.addr) {
1910                         __unregister_kprobe_bottom(&rps[i]->kp);
1911                         cleanup_rp_inst(rps[i]);
1912                 }
1913         }
1914 }
1915 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1916
1917 #else /* CONFIG_KRETPROBES */
1918 int __kprobes register_kretprobe(struct kretprobe *rp)
1919 {
1920         return -ENOSYS;
1921 }
1922 EXPORT_SYMBOL_GPL(register_kretprobe);
1923
1924 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
1925 {
1926         return -ENOSYS;
1927 }
1928 EXPORT_SYMBOL_GPL(register_kretprobes);
1929
1930 void __kprobes unregister_kretprobe(struct kretprobe *rp)
1931 {
1932 }
1933 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1934
1935 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
1936 {
1937 }
1938 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1939
1940 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
1941                                            struct pt_regs *regs)
1942 {
1943         return 0;
1944 }
1945
1946 #endif /* CONFIG_KRETPROBES */
1947
1948 /* Set the kprobe gone and remove its instruction buffer. */
1949 static void __kprobes kill_kprobe(struct kprobe *p)
1950 {
1951         struct kprobe *kp;
1952
1953         p->flags |= KPROBE_FLAG_GONE;
1954         if (kprobe_aggrprobe(p)) {
1955                 /*
1956                  * If this is an aggr_kprobe, we have to list all the
1957                  * chained probes and mark them GONE.
1958                  */
1959                 list_for_each_entry_rcu(kp, &p->list, list)
1960                         kp->flags |= KPROBE_FLAG_GONE;
1961                 p->post_handler = NULL;
1962                 p->break_handler = NULL;
1963                 kill_optimized_kprobe(p);
1964         }
1965         /*
1966          * Here, we can remove insn_slot safely, because no thread calls
1967          * the original probed function (which will be freed soon) any more.
1968          */
1969         arch_remove_kprobe(p);
1970 }
1971
1972 /* Disable one kprobe */
1973 int __kprobes disable_kprobe(struct kprobe *kp)
1974 {
1975         int ret = 0;
1976
1977         mutex_lock(&kprobe_mutex);
1978
1979         /* Disable this kprobe */
1980         if (__disable_kprobe(kp) == NULL)
1981                 ret = -EINVAL;
1982
1983         mutex_unlock(&kprobe_mutex);
1984         return ret;
1985 }
1986 EXPORT_SYMBOL_GPL(disable_kprobe);
1987
1988 /* Enable one kprobe */
1989 int __kprobes enable_kprobe(struct kprobe *kp)
1990 {
1991         int ret = 0;
1992         struct kprobe *p;
1993
1994         mutex_lock(&kprobe_mutex);
1995
1996         /* Check whether specified probe is valid. */
1997         p = __get_valid_kprobe(kp);
1998         if (unlikely(p == NULL)) {
1999                 ret = -EINVAL;
2000                 goto out;
2001         }
2002
2003         if (kprobe_gone(kp)) {
2004                 /* This kprobe has gone, we couldn't enable it. */
2005                 ret = -EINVAL;
2006                 goto out;
2007         }
2008
2009         if (p != kp)
2010                 kp->flags &= ~KPROBE_FLAG_DISABLED;
2011
2012         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2013                 p->flags &= ~KPROBE_FLAG_DISABLED;
2014                 arm_kprobe(p);
2015         }
2016 out:
2017         mutex_unlock(&kprobe_mutex);
2018         return ret;
2019 }
2020 EXPORT_SYMBOL_GPL(enable_kprobe);
2021
2022 void __kprobes dump_kprobe(struct kprobe *kp)
2023 {
2024         printk(KERN_WARNING "Dumping kprobe:\n");
2025         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2026                kp->symbol_name, kp->addr, kp->offset);
2027 }
2028
2029 /* Module notifier call back, checking kprobes on the module */
2030 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
2031                                              unsigned long val, void *data)
2032 {
2033         struct module *mod = data;
2034         struct hlist_head *head;
2035         struct kprobe *p;
2036         unsigned int i;
2037         int checkcore = (val == MODULE_STATE_GOING);
2038
2039         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2040                 return NOTIFY_DONE;
2041
2042         /*
2043          * When MODULE_STATE_GOING was notified, both of module .text and
2044          * .init.text sections would be freed. When MODULE_STATE_LIVE was
2045          * notified, only .init.text section would be freed. We need to
2046          * disable kprobes which have been inserted in the sections.
2047          */
2048         mutex_lock(&kprobe_mutex);
2049         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2050                 head = &kprobe_table[i];
2051                 hlist_for_each_entry_rcu(p, head, hlist)
2052                         if (within_module_init((unsigned long)p->addr, mod) ||
2053                             (checkcore &&
2054                              within_module_core((unsigned long)p->addr, mod))) {
2055                                 /*
2056                                  * The vaddr this probe is installed will soon
2057                                  * be vfreed buy not synced to disk. Hence,
2058                                  * disarming the breakpoint isn't needed.
2059                                  */
2060                                 kill_kprobe(p);
2061                         }
2062         }
2063         mutex_unlock(&kprobe_mutex);
2064         return NOTIFY_DONE;
2065 }
2066
2067 static struct notifier_block kprobe_module_nb = {
2068         .notifier_call = kprobes_module_callback,
2069         .priority = 0
2070 };
2071
2072 static int __init init_kprobes(void)
2073 {
2074         int i, err = 0;
2075         unsigned long offset = 0, size = 0;
2076         char *modname, namebuf[128];
2077         const char *symbol_name;
2078         void *addr;
2079         struct kprobe_blackpoint *kb;
2080
2081         /* FIXME allocate the probe table, currently defined statically */
2082         /* initialize all list heads */
2083         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2084                 INIT_HLIST_HEAD(&kprobe_table[i]);
2085                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2086                 raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2087         }
2088
2089         /*
2090          * Lookup and populate the kprobe_blacklist.
2091          *
2092          * Unlike the kretprobe blacklist, we'll need to determine
2093          * the range of addresses that belong to the said functions,
2094          * since a kprobe need not necessarily be at the beginning
2095          * of a function.
2096          */
2097         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
2098                 kprobe_lookup_name(kb->name, addr);
2099                 if (!addr)
2100                         continue;
2101
2102                 kb->start_addr = (unsigned long)addr;
2103                 symbol_name = kallsyms_lookup(kb->start_addr,
2104                                 &size, &offset, &modname, namebuf);
2105                 if (!symbol_name)
2106                         kb->range = 0;
2107                 else
2108                         kb->range = size;
2109         }
2110
2111         if (kretprobe_blacklist_size) {
2112                 /* lookup the function address from its name */
2113                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2114                         kprobe_lookup_name(kretprobe_blacklist[i].name,
2115                                            kretprobe_blacklist[i].addr);
2116                         if (!kretprobe_blacklist[i].addr)
2117                                 printk("kretprobe: lookup failed: %s\n",
2118                                        kretprobe_blacklist[i].name);
2119                 }
2120         }
2121
2122 #if defined(CONFIG_OPTPROBES)
2123 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2124         /* Init kprobe_optinsn_slots */
2125         kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2126 #endif
2127         /* By default, kprobes can be optimized */
2128         kprobes_allow_optimization = true;
2129 #endif
2130
2131         /* By default, kprobes are armed */
2132         kprobes_all_disarmed = false;
2133
2134         err = arch_init_kprobes();
2135         if (!err)
2136                 err = register_die_notifier(&kprobe_exceptions_nb);
2137         if (!err)
2138                 err = register_module_notifier(&kprobe_module_nb);
2139
2140         kprobes_initialized = (err == 0);
2141
2142         if (!err)
2143                 init_test_probes();
2144         return err;
2145 }
2146
2147 #ifdef CONFIG_DEBUG_FS
2148 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
2149                 const char *sym, int offset, char *modname, struct kprobe *pp)
2150 {
2151         char *kprobe_type;
2152
2153         if (p->pre_handler == pre_handler_kretprobe)
2154                 kprobe_type = "r";
2155         else if (p->pre_handler == setjmp_pre_handler)
2156                 kprobe_type = "j";
2157         else
2158                 kprobe_type = "k";
2159
2160         if (sym)
2161                 seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2162                         p->addr, kprobe_type, sym, offset,
2163                         (modname ? modname : " "));
2164         else
2165                 seq_printf(pi, "%p  %s  %p ",
2166                         p->addr, kprobe_type, p->addr);
2167
2168         if (!pp)
2169                 pp = p;
2170         seq_printf(pi, "%s%s%s%s\n",
2171                 (kprobe_gone(p) ? "[GONE]" : ""),
2172                 ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2173                 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2174                 (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2175 }
2176
2177 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2178 {
2179         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2180 }
2181
2182 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2183 {
2184         (*pos)++;
2185         if (*pos >= KPROBE_TABLE_SIZE)
2186                 return NULL;
2187         return pos;
2188 }
2189
2190 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
2191 {
2192         /* Nothing to do */
2193 }
2194
2195 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
2196 {
2197         struct hlist_head *head;
2198         struct kprobe *p, *kp;
2199         const char *sym = NULL;
2200         unsigned int i = *(loff_t *) v;
2201         unsigned long offset = 0;
2202         char *modname, namebuf[128];
2203
2204         head = &kprobe_table[i];
2205         preempt_disable();
2206         hlist_for_each_entry_rcu(p, head, hlist) {
2207                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2208                                         &offset, &modname, namebuf);
2209                 if (kprobe_aggrprobe(p)) {
2210                         list_for_each_entry_rcu(kp, &p->list, list)
2211                                 report_probe(pi, kp, sym, offset, modname, p);
2212                 } else
2213                         report_probe(pi, p, sym, offset, modname, NULL);
2214         }
2215         preempt_enable();
2216         return 0;
2217 }
2218
2219 static const struct seq_operations kprobes_seq_ops = {
2220         .start = kprobe_seq_start,
2221         .next  = kprobe_seq_next,
2222         .stop  = kprobe_seq_stop,
2223         .show  = show_kprobe_addr
2224 };
2225
2226 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
2227 {
2228         return seq_open(filp, &kprobes_seq_ops);
2229 }
2230
2231 static const struct file_operations debugfs_kprobes_operations = {
2232         .open           = kprobes_open,
2233         .read           = seq_read,
2234         .llseek         = seq_lseek,
2235         .release        = seq_release,
2236 };
2237
2238 static void __kprobes arm_all_kprobes(void)
2239 {
2240         struct hlist_head *head;
2241         struct kprobe *p;
2242         unsigned int i;
2243
2244         mutex_lock(&kprobe_mutex);
2245
2246         /* If kprobes are armed, just return */
2247         if (!kprobes_all_disarmed)
2248                 goto already_enabled;
2249
2250         /* Arming kprobes doesn't optimize kprobe itself */
2251         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2252                 head = &kprobe_table[i];
2253                 hlist_for_each_entry_rcu(p, head, hlist)
2254                         if (!kprobe_disabled(p))
2255                                 arm_kprobe(p);
2256         }
2257
2258         kprobes_all_disarmed = false;
2259         printk(KERN_INFO "Kprobes globally enabled\n");
2260
2261 already_enabled:
2262         mutex_unlock(&kprobe_mutex);
2263         return;
2264 }
2265
2266 static void __kprobes disarm_all_kprobes(void)
2267 {
2268         struct hlist_head *head;
2269         struct kprobe *p;
2270         unsigned int i;
2271
2272         mutex_lock(&kprobe_mutex);
2273
2274         /* If kprobes are already disarmed, just return */
2275         if (kprobes_all_disarmed) {
2276                 mutex_unlock(&kprobe_mutex);
2277                 return;
2278         }
2279
2280         kprobes_all_disarmed = true;
2281         printk(KERN_INFO "Kprobes globally disabled\n");
2282
2283         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2284                 head = &kprobe_table[i];
2285                 hlist_for_each_entry_rcu(p, head, hlist) {
2286                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2287                                 disarm_kprobe(p, false);
2288                 }
2289         }
2290         mutex_unlock(&kprobe_mutex);
2291
2292         /* Wait for disarming all kprobes by optimizer */
2293         wait_for_kprobe_optimizer();
2294 }
2295
2296 /*
2297  * XXX: The debugfs bool file interface doesn't allow for callbacks
2298  * when the bool state is switched. We can reuse that facility when
2299  * available
2300  */
2301 static ssize_t read_enabled_file_bool(struct file *file,
2302                char __user *user_buf, size_t count, loff_t *ppos)
2303 {
2304         char buf[3];
2305
2306         if (!kprobes_all_disarmed)
2307                 buf[0] = '1';
2308         else
2309                 buf[0] = '0';
2310         buf[1] = '\n';
2311         buf[2] = 0x00;
2312         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2313 }
2314
2315 static ssize_t write_enabled_file_bool(struct file *file,
2316                const char __user *user_buf, size_t count, loff_t *ppos)
2317 {
2318         char buf[32];
2319         size_t buf_size;
2320
2321         buf_size = min(count, (sizeof(buf)-1));
2322         if (copy_from_user(buf, user_buf, buf_size))
2323                 return -EFAULT;
2324
2325         switch (buf[0]) {
2326         case 'y':
2327         case 'Y':
2328         case '1':
2329                 arm_all_kprobes();
2330                 break;
2331         case 'n':
2332         case 'N':
2333         case '0':
2334                 disarm_all_kprobes();
2335                 break;
2336         }
2337
2338         return count;
2339 }
2340
2341 static const struct file_operations fops_kp = {
2342         .read =         read_enabled_file_bool,
2343         .write =        write_enabled_file_bool,
2344         .llseek =       default_llseek,
2345 };
2346
2347 static int __kprobes debugfs_kprobe_init(void)
2348 {
2349         struct dentry *dir, *file;
2350         unsigned int value = 1;
2351
2352         dir = debugfs_create_dir("kprobes", NULL);
2353         if (!dir)
2354                 return -ENOMEM;
2355
2356         file = debugfs_create_file("list", 0444, dir, NULL,
2357                                 &debugfs_kprobes_operations);
2358         if (!file) {
2359                 debugfs_remove(dir);
2360                 return -ENOMEM;
2361         }
2362
2363         file = debugfs_create_file("enabled", 0600, dir,
2364                                         &value, &fops_kp);
2365         if (!file) {
2366                 debugfs_remove(dir);
2367                 return -ENOMEM;
2368         }
2369
2370         return 0;
2371 }
2372
2373 late_initcall(debugfs_kprobe_init);
2374 #endif /* CONFIG_DEBUG_FS */
2375
2376 module_init(init_kprobes);
2377
2378 /* defined in arch/.../kernel/kprobes.c */
2379 EXPORT_SYMBOL_GPL(jprobe_return);