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