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