kprobes.c revision 25764288d8dc4792f0f487baf043ccfee5d8c2ba
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 70static int kprobes_initialized; 71static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; 72static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; 73 74/* NOTE: change this value only with kprobe_mutex held */ 75static bool kprobes_all_disarmed; 76 77/* This protects kprobe_table and optimizing_list */ 78static DEFINE_MUTEX(kprobe_mutex); 79static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; 80static struct { 81 raw_spinlock_t lock ____cacheline_aligned_in_smp; 82} kretprobe_table_locks[KPROBE_TABLE_SIZE]; 83 84static 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 */ 96static 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 */ 112struct 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 124struct 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 130static int slots_per_page(struct kprobe_insn_cache *c) 131{ 132 return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t)); 133} 134 135enum kprobe_slot_state { 136 SLOT_CLEAN = 0, 137 SLOT_DIRTY = 1, 138 SLOT_USED = 2, 139}; 140 141static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */ 142static 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}; 147static 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 */ 153static 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 203kprobe_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. */ 215static 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 236static 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 258static 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 282void __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 */ 290static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */ 291static 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 */ 297kprobe_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 308void __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 */ 318static inline void set_kprobe_instance(struct kprobe *kp) 319{ 320 __this_cpu_write(kprobe_instance, kp); 321} 322 323static 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 */ 334struct 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 349static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs); 350 351/* Return true if the kprobe is an aggregator */ 352static 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 */ 358static 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 */ 367static 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 */ 375static 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 */ 381void __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 */ 395static __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. */ 406static 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 */ 419static 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 */ 433static 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 */ 449static 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 */ 469static LIST_HEAD(optimizing_list); 470static LIST_HEAD(unoptimizing_list); 471 472static void kprobe_optimizer(struct work_struct *work); 473static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer); 474static 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 */ 481static __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 */ 509static __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 */ 541static __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 */ 553static __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 */ 560static __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 */ 601static __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 */ 608static __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 */ 642static __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 */ 652static __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 */ 691static 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 */ 712static 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 */ 727static __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 */ 736static __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 751static 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 */ 757static __kprobes void try_to_optimize_kprobe(struct kprobe *p) 758{ 759 struct kprobe *ap; 760 struct optimized_kprobe *op; 761 762 /* For preparing optimization, jump_label_text_reserved() is called */ 763 jump_label_lock(); 764 mutex_lock(&text_mutex); 765 766 ap = alloc_aggr_kprobe(p); 767 if (!ap) 768 goto out; 769 770 op = container_of(ap, struct optimized_kprobe, kp); 771 if (!arch_prepared_optinsn(&op->optinsn)) { 772 /* If failed to setup optimizing, fallback to kprobe */ 773 arch_remove_optimized_kprobe(op); 774 kfree(op); 775 goto out; 776 } 777 778 init_aggr_kprobe(ap, p); 779 optimize_kprobe(ap); /* This just kicks optimizer thread */ 780 781out: 782 mutex_unlock(&text_mutex); 783 jump_label_unlock(); 784} 785 786#ifdef CONFIG_SYSCTL 787/* This should be called with kprobe_mutex locked */ 788static 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 */ 810static 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 834int sysctl_kprobes_optimization; 835int 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 */ 856static 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 */ 871static 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 */ 900static 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 906static __kprobes void free_aggr_kprobe(struct kprobe *p) 907{ 908 arch_remove_kprobe(p); 909 kfree(p); 910} 911 912static __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 */ 919static 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 */ 932static 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 */ 944static 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 959static 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 973static 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 989static 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 */ 1003void __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 1015void __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 1032void __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 1044static 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 1052void __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 1063static 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 */ 1077void __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 1103static 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 1114static 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*/ 1138static 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 return 0; 1156} 1157 1158/* 1159 * Fill in the required fields of the "manager kprobe". Replace the 1160 * earlier kprobe in the hlist with the manager kprobe 1161 */ 1162static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p) 1163{ 1164 /* Copy p's insn slot to ap */ 1165 copy_kprobe(p, ap); 1166 flush_insn_slot(ap); 1167 ap->addr = p->addr; 1168 ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED; 1169 ap->pre_handler = aggr_pre_handler; 1170 ap->fault_handler = aggr_fault_handler; 1171 /* We don't care the kprobe which has gone. */ 1172 if (p->post_handler && !kprobe_gone(p)) 1173 ap->post_handler = aggr_post_handler; 1174 if (p->break_handler && !kprobe_gone(p)) 1175 ap->break_handler = aggr_break_handler; 1176 1177 INIT_LIST_HEAD(&ap->list); 1178 INIT_HLIST_NODE(&ap->hlist); 1179 1180 list_add_rcu(&p->list, &ap->list); 1181 hlist_replace_rcu(&p->hlist, &ap->hlist); 1182} 1183 1184/* 1185 * This is the second or subsequent kprobe at the address - handle 1186 * the intricacies 1187 */ 1188static int __kprobes register_aggr_kprobe(struct kprobe *orig_p, 1189 struct kprobe *p) 1190{ 1191 int ret = 0; 1192 struct kprobe *ap = orig_p; 1193 1194 /* For preparing optimization, jump_label_text_reserved() is called */ 1195 jump_label_lock(); 1196 /* 1197 * Get online CPUs to avoid text_mutex deadlock.with stop machine, 1198 * which is invoked by unoptimize_kprobe() in add_new_kprobe() 1199 */ 1200 get_online_cpus(); 1201 mutex_lock(&text_mutex); 1202 1203 if (!kprobe_aggrprobe(orig_p)) { 1204 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */ 1205 ap = alloc_aggr_kprobe(orig_p); 1206 if (!ap) { 1207 ret = -ENOMEM; 1208 goto out; 1209 } 1210 init_aggr_kprobe(ap, orig_p); 1211 } else if (kprobe_unused(ap)) 1212 /* This probe is going to die. Rescue it */ 1213 reuse_unused_kprobe(ap); 1214 1215 if (kprobe_gone(ap)) { 1216 /* 1217 * Attempting to insert new probe at the same location that 1218 * had a probe in the module vaddr area which already 1219 * freed. So, the instruction slot has already been 1220 * released. We need a new slot for the new probe. 1221 */ 1222 ret = arch_prepare_kprobe(ap); 1223 if (ret) 1224 /* 1225 * Even if fail to allocate new slot, don't need to 1226 * free aggr_probe. It will be used next time, or 1227 * freed by unregister_kprobe. 1228 */ 1229 goto out; 1230 1231 /* Prepare optimized instructions if possible. */ 1232 prepare_optimized_kprobe(ap); 1233 1234 /* 1235 * Clear gone flag to prevent allocating new slot again, and 1236 * set disabled flag because it is not armed yet. 1237 */ 1238 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE) 1239 | KPROBE_FLAG_DISABLED; 1240 } 1241 1242 /* Copy ap's insn slot to p */ 1243 copy_kprobe(ap, p); 1244 ret = add_new_kprobe(ap, p); 1245 1246out: 1247 mutex_unlock(&text_mutex); 1248 put_online_cpus(); 1249 jump_label_unlock(); 1250 1251 if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) { 1252 ap->flags &= ~KPROBE_FLAG_DISABLED; 1253 if (!kprobes_all_disarmed) 1254 /* Arm the breakpoint again. */ 1255 arm_kprobe(ap); 1256 } 1257 return ret; 1258} 1259 1260static int __kprobes in_kprobes_functions(unsigned long addr) 1261{ 1262 struct kprobe_blackpoint *kb; 1263 1264 if (addr >= (unsigned long)__kprobes_text_start && 1265 addr < (unsigned long)__kprobes_text_end) 1266 return -EINVAL; 1267 /* 1268 * If there exists a kprobe_blacklist, verify and 1269 * fail any probe registration in the prohibited area 1270 */ 1271 for (kb = kprobe_blacklist; kb->name != NULL; kb++) { 1272 if (kb->start_addr) { 1273 if (addr >= kb->start_addr && 1274 addr < (kb->start_addr + kb->range)) 1275 return -EINVAL; 1276 } 1277 } 1278 return 0; 1279} 1280 1281/* 1282 * If we have a symbol_name argument, look it up and add the offset field 1283 * to it. This way, we can specify a relative address to a symbol. 1284 * This returns encoded errors if it fails to look up symbol or invalid 1285 * combination of parameters. 1286 */ 1287static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p) 1288{ 1289 kprobe_opcode_t *addr = p->addr; 1290 1291 if ((p->symbol_name && p->addr) || 1292 (!p->symbol_name && !p->addr)) 1293 goto invalid; 1294 1295 if (p->symbol_name) { 1296 kprobe_lookup_name(p->symbol_name, addr); 1297 if (!addr) 1298 return ERR_PTR(-ENOENT); 1299 } 1300 1301 addr = (kprobe_opcode_t *)(((char *)addr) + p->offset); 1302 if (addr) 1303 return addr; 1304 1305invalid: 1306 return ERR_PTR(-EINVAL); 1307} 1308 1309/* Check passed kprobe is valid and return kprobe in kprobe_table. */ 1310static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p) 1311{ 1312 struct kprobe *ap, *list_p; 1313 1314 ap = get_kprobe(p->addr); 1315 if (unlikely(!ap)) 1316 return NULL; 1317 1318 if (p != ap) { 1319 list_for_each_entry_rcu(list_p, &ap->list, list) 1320 if (list_p == p) 1321 /* kprobe p is a valid probe */ 1322 goto valid; 1323 return NULL; 1324 } 1325valid: 1326 return ap; 1327} 1328 1329/* Return error if the kprobe is being re-registered */ 1330static inline int check_kprobe_rereg(struct kprobe *p) 1331{ 1332 int ret = 0; 1333 1334 mutex_lock(&kprobe_mutex); 1335 if (__get_valid_kprobe(p)) 1336 ret = -EINVAL; 1337 mutex_unlock(&kprobe_mutex); 1338 1339 return ret; 1340} 1341 1342static __kprobes int check_kprobe_address_safe(struct kprobe *p, 1343 struct module **probed_mod) 1344{ 1345 int ret = 0; 1346 1347 jump_label_lock(); 1348 preempt_disable(); 1349 1350 /* Ensure it is not in reserved area nor out of text */ 1351 if (!kernel_text_address((unsigned long) p->addr) || 1352 in_kprobes_functions((unsigned long) p->addr) || 1353 ftrace_text_reserved(p->addr, p->addr) || 1354 jump_label_text_reserved(p->addr, p->addr)) { 1355 ret = -EINVAL; 1356 goto out; 1357 } 1358 1359 /* Check if are we probing a module */ 1360 *probed_mod = __module_text_address((unsigned long) p->addr); 1361 if (*probed_mod) { 1362 /* 1363 * We must hold a refcount of the probed module while updating 1364 * its code to prohibit unexpected unloading. 1365 */ 1366 if (unlikely(!try_module_get(*probed_mod))) { 1367 ret = -ENOENT; 1368 goto out; 1369 } 1370 1371 /* 1372 * If the module freed .init.text, we couldn't insert 1373 * kprobes in there. 1374 */ 1375 if (within_module_init((unsigned long)p->addr, *probed_mod) && 1376 (*probed_mod)->state != MODULE_STATE_COMING) { 1377 module_put(*probed_mod); 1378 *probed_mod = NULL; 1379 ret = -ENOENT; 1380 } 1381 } 1382out: 1383 preempt_enable(); 1384 jump_label_unlock(); 1385 1386 return ret; 1387} 1388 1389int __kprobes register_kprobe(struct kprobe *p) 1390{ 1391 int ret; 1392 struct kprobe *old_p; 1393 struct module *probed_mod; 1394 kprobe_opcode_t *addr; 1395 1396 /* Adjust probe address from symbol */ 1397 addr = kprobe_addr(p); 1398 if (IS_ERR(addr)) 1399 return PTR_ERR(addr); 1400 p->addr = addr; 1401 1402 ret = check_kprobe_rereg(p); 1403 if (ret) 1404 return ret; 1405 1406 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ 1407 p->flags &= KPROBE_FLAG_DISABLED; 1408 p->nmissed = 0; 1409 INIT_LIST_HEAD(&p->list); 1410 1411 ret = check_kprobe_address_safe(p, &probed_mod); 1412 if (ret) 1413 return ret; 1414 1415 mutex_lock(&kprobe_mutex); 1416 1417 old_p = get_kprobe(p->addr); 1418 if (old_p) { 1419 /* Since this may unoptimize old_p, locking text_mutex. */ 1420 ret = register_aggr_kprobe(old_p, p); 1421 goto out; 1422 } 1423 1424 mutex_lock(&text_mutex); /* Avoiding text modification */ 1425 ret = arch_prepare_kprobe(p); 1426 mutex_unlock(&text_mutex); 1427 if (ret) 1428 goto out; 1429 1430 INIT_HLIST_NODE(&p->hlist); 1431 hlist_add_head_rcu(&p->hlist, 1432 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); 1433 1434 if (!kprobes_all_disarmed && !kprobe_disabled(p)) 1435 arm_kprobe(p); 1436 1437 /* Try to optimize kprobe */ 1438 try_to_optimize_kprobe(p); 1439 1440out: 1441 mutex_unlock(&kprobe_mutex); 1442 1443 if (probed_mod) 1444 module_put(probed_mod); 1445 1446 return ret; 1447} 1448EXPORT_SYMBOL_GPL(register_kprobe); 1449 1450/* Check if all probes on the aggrprobe are disabled */ 1451static int __kprobes aggr_kprobe_disabled(struct kprobe *ap) 1452{ 1453 struct kprobe *kp; 1454 1455 list_for_each_entry_rcu(kp, &ap->list, list) 1456 if (!kprobe_disabled(kp)) 1457 /* 1458 * There is an active probe on the list. 1459 * We can't disable this ap. 1460 */ 1461 return 0; 1462 1463 return 1; 1464} 1465 1466/* Disable one kprobe: Make sure called under kprobe_mutex is locked */ 1467static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p) 1468{ 1469 struct kprobe *orig_p; 1470 1471 /* Get an original kprobe for return */ 1472 orig_p = __get_valid_kprobe(p); 1473 if (unlikely(orig_p == NULL)) 1474 return NULL; 1475 1476 if (!kprobe_disabled(p)) { 1477 /* Disable probe if it is a child probe */ 1478 if (p != orig_p) 1479 p->flags |= KPROBE_FLAG_DISABLED; 1480 1481 /* Try to disarm and disable this/parent probe */ 1482 if (p == orig_p || aggr_kprobe_disabled(orig_p)) { 1483 disarm_kprobe(orig_p); 1484 orig_p->flags |= KPROBE_FLAG_DISABLED; 1485 } 1486 } 1487 1488 return orig_p; 1489} 1490 1491/* 1492 * Unregister a kprobe without a scheduler synchronization. 1493 */ 1494static int __kprobes __unregister_kprobe_top(struct kprobe *p) 1495{ 1496 struct kprobe *ap, *list_p; 1497 1498 /* Disable kprobe. This will disarm it if needed. */ 1499 ap = __disable_kprobe(p); 1500 if (ap == NULL) 1501 return -EINVAL; 1502 1503 if (ap == p) 1504 /* 1505 * This probe is an independent(and non-optimized) kprobe 1506 * (not an aggrprobe). Remove from the hash list. 1507 */ 1508 goto disarmed; 1509 1510 /* Following process expects this probe is an aggrprobe */ 1511 WARN_ON(!kprobe_aggrprobe(ap)); 1512 1513 if (list_is_singular(&ap->list) && kprobe_disarmed(ap)) 1514 /* 1515 * !disarmed could be happen if the probe is under delayed 1516 * unoptimizing. 1517 */ 1518 goto disarmed; 1519 else { 1520 /* If disabling probe has special handlers, update aggrprobe */ 1521 if (p->break_handler && !kprobe_gone(p)) 1522 ap->break_handler = NULL; 1523 if (p->post_handler && !kprobe_gone(p)) { 1524 list_for_each_entry_rcu(list_p, &ap->list, list) { 1525 if ((list_p != p) && (list_p->post_handler)) 1526 goto noclean; 1527 } 1528 ap->post_handler = NULL; 1529 } 1530noclean: 1531 /* 1532 * Remove from the aggrprobe: this path will do nothing in 1533 * __unregister_kprobe_bottom(). 1534 */ 1535 list_del_rcu(&p->list); 1536 if (!kprobe_disabled(ap) && !kprobes_all_disarmed) 1537 /* 1538 * Try to optimize this probe again, because post 1539 * handler may have been changed. 1540 */ 1541 optimize_kprobe(ap); 1542 } 1543 return 0; 1544 1545disarmed: 1546 BUG_ON(!kprobe_disarmed(ap)); 1547 hlist_del_rcu(&ap->hlist); 1548 return 0; 1549} 1550 1551static void __kprobes __unregister_kprobe_bottom(struct kprobe *p) 1552{ 1553 struct kprobe *ap; 1554 1555 if (list_empty(&p->list)) 1556 /* This is an independent kprobe */ 1557 arch_remove_kprobe(p); 1558 else if (list_is_singular(&p->list)) { 1559 /* This is the last child of an aggrprobe */ 1560 ap = list_entry(p->list.next, struct kprobe, list); 1561 list_del(&p->list); 1562 free_aggr_kprobe(ap); 1563 } 1564 /* Otherwise, do nothing. */ 1565} 1566 1567int __kprobes register_kprobes(struct kprobe **kps, int num) 1568{ 1569 int i, ret = 0; 1570 1571 if (num <= 0) 1572 return -EINVAL; 1573 for (i = 0; i < num; i++) { 1574 ret = register_kprobe(kps[i]); 1575 if (ret < 0) { 1576 if (i > 0) 1577 unregister_kprobes(kps, i); 1578 break; 1579 } 1580 } 1581 return ret; 1582} 1583EXPORT_SYMBOL_GPL(register_kprobes); 1584 1585void __kprobes unregister_kprobe(struct kprobe *p) 1586{ 1587 unregister_kprobes(&p, 1); 1588} 1589EXPORT_SYMBOL_GPL(unregister_kprobe); 1590 1591void __kprobes unregister_kprobes(struct kprobe **kps, int num) 1592{ 1593 int i; 1594 1595 if (num <= 0) 1596 return; 1597 mutex_lock(&kprobe_mutex); 1598 for (i = 0; i < num; i++) 1599 if (__unregister_kprobe_top(kps[i]) < 0) 1600 kps[i]->addr = NULL; 1601 mutex_unlock(&kprobe_mutex); 1602 1603 synchronize_sched(); 1604 for (i = 0; i < num; i++) 1605 if (kps[i]->addr) 1606 __unregister_kprobe_bottom(kps[i]); 1607} 1608EXPORT_SYMBOL_GPL(unregister_kprobes); 1609 1610static struct notifier_block kprobe_exceptions_nb = { 1611 .notifier_call = kprobe_exceptions_notify, 1612 .priority = 0x7fffffff /* we need to be notified first */ 1613}; 1614 1615unsigned long __weak arch_deref_entry_point(void *entry) 1616{ 1617 return (unsigned long)entry; 1618} 1619 1620int __kprobes register_jprobes(struct jprobe **jps, int num) 1621{ 1622 struct jprobe *jp; 1623 int ret = 0, i; 1624 1625 if (num <= 0) 1626 return -EINVAL; 1627 for (i = 0; i < num; i++) { 1628 unsigned long addr, offset; 1629 jp = jps[i]; 1630 addr = arch_deref_entry_point(jp->entry); 1631 1632 /* Verify probepoint is a function entry point */ 1633 if (kallsyms_lookup_size_offset(addr, NULL, &offset) && 1634 offset == 0) { 1635 jp->kp.pre_handler = setjmp_pre_handler; 1636 jp->kp.break_handler = longjmp_break_handler; 1637 ret = register_kprobe(&jp->kp); 1638 } else 1639 ret = -EINVAL; 1640 1641 if (ret < 0) { 1642 if (i > 0) 1643 unregister_jprobes(jps, i); 1644 break; 1645 } 1646 } 1647 return ret; 1648} 1649EXPORT_SYMBOL_GPL(register_jprobes); 1650 1651int __kprobes register_jprobe(struct jprobe *jp) 1652{ 1653 return register_jprobes(&jp, 1); 1654} 1655EXPORT_SYMBOL_GPL(register_jprobe); 1656 1657void __kprobes unregister_jprobe(struct jprobe *jp) 1658{ 1659 unregister_jprobes(&jp, 1); 1660} 1661EXPORT_SYMBOL_GPL(unregister_jprobe); 1662 1663void __kprobes unregister_jprobes(struct jprobe **jps, int num) 1664{ 1665 int i; 1666 1667 if (num <= 0) 1668 return; 1669 mutex_lock(&kprobe_mutex); 1670 for (i = 0; i < num; i++) 1671 if (__unregister_kprobe_top(&jps[i]->kp) < 0) 1672 jps[i]->kp.addr = NULL; 1673 mutex_unlock(&kprobe_mutex); 1674 1675 synchronize_sched(); 1676 for (i = 0; i < num; i++) { 1677 if (jps[i]->kp.addr) 1678 __unregister_kprobe_bottom(&jps[i]->kp); 1679 } 1680} 1681EXPORT_SYMBOL_GPL(unregister_jprobes); 1682 1683#ifdef CONFIG_KRETPROBES 1684/* 1685 * This kprobe pre_handler is registered with every kretprobe. When probe 1686 * hits it will set up the return probe. 1687 */ 1688static int __kprobes pre_handler_kretprobe(struct kprobe *p, 1689 struct pt_regs *regs) 1690{ 1691 struct kretprobe *rp = container_of(p, struct kretprobe, kp); 1692 unsigned long hash, flags = 0; 1693 struct kretprobe_instance *ri; 1694 1695 /*TODO: consider to only swap the RA after the last pre_handler fired */ 1696 hash = hash_ptr(current, KPROBE_HASH_BITS); 1697 raw_spin_lock_irqsave(&rp->lock, flags); 1698 if (!hlist_empty(&rp->free_instances)) { 1699 ri = hlist_entry(rp->free_instances.first, 1700 struct kretprobe_instance, hlist); 1701 hlist_del(&ri->hlist); 1702 raw_spin_unlock_irqrestore(&rp->lock, flags); 1703 1704 ri->rp = rp; 1705 ri->task = current; 1706 1707 if (rp->entry_handler && rp->entry_handler(ri, regs)) { 1708 raw_spin_lock_irqsave(&rp->lock, flags); 1709 hlist_add_head(&ri->hlist, &rp->free_instances); 1710 raw_spin_unlock_irqrestore(&rp->lock, flags); 1711 return 0; 1712 } 1713 1714 arch_prepare_kretprobe(ri, regs); 1715 1716 /* XXX(hch): why is there no hlist_move_head? */ 1717 INIT_HLIST_NODE(&ri->hlist); 1718 kretprobe_table_lock(hash, &flags); 1719 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]); 1720 kretprobe_table_unlock(hash, &flags); 1721 } else { 1722 rp->nmissed++; 1723 raw_spin_unlock_irqrestore(&rp->lock, flags); 1724 } 1725 return 0; 1726} 1727 1728int __kprobes register_kretprobe(struct kretprobe *rp) 1729{ 1730 int ret = 0; 1731 struct kretprobe_instance *inst; 1732 int i; 1733 void *addr; 1734 1735 if (kretprobe_blacklist_size) { 1736 addr = kprobe_addr(&rp->kp); 1737 if (IS_ERR(addr)) 1738 return PTR_ERR(addr); 1739 1740 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { 1741 if (kretprobe_blacklist[i].addr == addr) 1742 return -EINVAL; 1743 } 1744 } 1745 1746 rp->kp.pre_handler = pre_handler_kretprobe; 1747 rp->kp.post_handler = NULL; 1748 rp->kp.fault_handler = NULL; 1749 rp->kp.break_handler = NULL; 1750 1751 /* Pre-allocate memory for max kretprobe instances */ 1752 if (rp->maxactive <= 0) { 1753#ifdef CONFIG_PREEMPT 1754 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus()); 1755#else 1756 rp->maxactive = num_possible_cpus(); 1757#endif 1758 } 1759 raw_spin_lock_init(&rp->lock); 1760 INIT_HLIST_HEAD(&rp->free_instances); 1761 for (i = 0; i < rp->maxactive; i++) { 1762 inst = kmalloc(sizeof(struct kretprobe_instance) + 1763 rp->data_size, GFP_KERNEL); 1764 if (inst == NULL) { 1765 free_rp_inst(rp); 1766 return -ENOMEM; 1767 } 1768 INIT_HLIST_NODE(&inst->hlist); 1769 hlist_add_head(&inst->hlist, &rp->free_instances); 1770 } 1771 1772 rp->nmissed = 0; 1773 /* Establish function entry probe point */ 1774 ret = register_kprobe(&rp->kp); 1775 if (ret != 0) 1776 free_rp_inst(rp); 1777 return ret; 1778} 1779EXPORT_SYMBOL_GPL(register_kretprobe); 1780 1781int __kprobes register_kretprobes(struct kretprobe **rps, int num) 1782{ 1783 int ret = 0, i; 1784 1785 if (num <= 0) 1786 return -EINVAL; 1787 for (i = 0; i < num; i++) { 1788 ret = register_kretprobe(rps[i]); 1789 if (ret < 0) { 1790 if (i > 0) 1791 unregister_kretprobes(rps, i); 1792 break; 1793 } 1794 } 1795 return ret; 1796} 1797EXPORT_SYMBOL_GPL(register_kretprobes); 1798 1799void __kprobes unregister_kretprobe(struct kretprobe *rp) 1800{ 1801 unregister_kretprobes(&rp, 1); 1802} 1803EXPORT_SYMBOL_GPL(unregister_kretprobe); 1804 1805void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) 1806{ 1807 int i; 1808 1809 if (num <= 0) 1810 return; 1811 mutex_lock(&kprobe_mutex); 1812 for (i = 0; i < num; i++) 1813 if (__unregister_kprobe_top(&rps[i]->kp) < 0) 1814 rps[i]->kp.addr = NULL; 1815 mutex_unlock(&kprobe_mutex); 1816 1817 synchronize_sched(); 1818 for (i = 0; i < num; i++) { 1819 if (rps[i]->kp.addr) { 1820 __unregister_kprobe_bottom(&rps[i]->kp); 1821 cleanup_rp_inst(rps[i]); 1822 } 1823 } 1824} 1825EXPORT_SYMBOL_GPL(unregister_kretprobes); 1826 1827#else /* CONFIG_KRETPROBES */ 1828int __kprobes register_kretprobe(struct kretprobe *rp) 1829{ 1830 return -ENOSYS; 1831} 1832EXPORT_SYMBOL_GPL(register_kretprobe); 1833 1834int __kprobes register_kretprobes(struct kretprobe **rps, int num) 1835{ 1836 return -ENOSYS; 1837} 1838EXPORT_SYMBOL_GPL(register_kretprobes); 1839 1840void __kprobes unregister_kretprobe(struct kretprobe *rp) 1841{ 1842} 1843EXPORT_SYMBOL_GPL(unregister_kretprobe); 1844 1845void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) 1846{ 1847} 1848EXPORT_SYMBOL_GPL(unregister_kretprobes); 1849 1850static int __kprobes pre_handler_kretprobe(struct kprobe *p, 1851 struct pt_regs *regs) 1852{ 1853 return 0; 1854} 1855 1856#endif /* CONFIG_KRETPROBES */ 1857 1858/* Set the kprobe gone and remove its instruction buffer. */ 1859static void __kprobes kill_kprobe(struct kprobe *p) 1860{ 1861 struct kprobe *kp; 1862 1863 p->flags |= KPROBE_FLAG_GONE; 1864 if (kprobe_aggrprobe(p)) { 1865 /* 1866 * If this is an aggr_kprobe, we have to list all the 1867 * chained probes and mark them GONE. 1868 */ 1869 list_for_each_entry_rcu(kp, &p->list, list) 1870 kp->flags |= KPROBE_FLAG_GONE; 1871 p->post_handler = NULL; 1872 p->break_handler = NULL; 1873 kill_optimized_kprobe(p); 1874 } 1875 /* 1876 * Here, we can remove insn_slot safely, because no thread calls 1877 * the original probed function (which will be freed soon) any more. 1878 */ 1879 arch_remove_kprobe(p); 1880} 1881 1882/* Disable one kprobe */ 1883int __kprobes disable_kprobe(struct kprobe *kp) 1884{ 1885 int ret = 0; 1886 1887 mutex_lock(&kprobe_mutex); 1888 1889 /* Disable this kprobe */ 1890 if (__disable_kprobe(kp) == NULL) 1891 ret = -EINVAL; 1892 1893 mutex_unlock(&kprobe_mutex); 1894 return ret; 1895} 1896EXPORT_SYMBOL_GPL(disable_kprobe); 1897 1898/* Enable one kprobe */ 1899int __kprobes enable_kprobe(struct kprobe *kp) 1900{ 1901 int ret = 0; 1902 struct kprobe *p; 1903 1904 mutex_lock(&kprobe_mutex); 1905 1906 /* Check whether specified probe is valid. */ 1907 p = __get_valid_kprobe(kp); 1908 if (unlikely(p == NULL)) { 1909 ret = -EINVAL; 1910 goto out; 1911 } 1912 1913 if (kprobe_gone(kp)) { 1914 /* This kprobe has gone, we couldn't enable it. */ 1915 ret = -EINVAL; 1916 goto out; 1917 } 1918 1919 if (p != kp) 1920 kp->flags &= ~KPROBE_FLAG_DISABLED; 1921 1922 if (!kprobes_all_disarmed && kprobe_disabled(p)) { 1923 p->flags &= ~KPROBE_FLAG_DISABLED; 1924 arm_kprobe(p); 1925 } 1926out: 1927 mutex_unlock(&kprobe_mutex); 1928 return ret; 1929} 1930EXPORT_SYMBOL_GPL(enable_kprobe); 1931 1932void __kprobes dump_kprobe(struct kprobe *kp) 1933{ 1934 printk(KERN_WARNING "Dumping kprobe:\n"); 1935 printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n", 1936 kp->symbol_name, kp->addr, kp->offset); 1937} 1938 1939/* Module notifier call back, checking kprobes on the module */ 1940static int __kprobes kprobes_module_callback(struct notifier_block *nb, 1941 unsigned long val, void *data) 1942{ 1943 struct module *mod = data; 1944 struct hlist_head *head; 1945 struct hlist_node *node; 1946 struct kprobe *p; 1947 unsigned int i; 1948 int checkcore = (val == MODULE_STATE_GOING); 1949 1950 if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE) 1951 return NOTIFY_DONE; 1952 1953 /* 1954 * When MODULE_STATE_GOING was notified, both of module .text and 1955 * .init.text sections would be freed. When MODULE_STATE_LIVE was 1956 * notified, only .init.text section would be freed. We need to 1957 * disable kprobes which have been inserted in the sections. 1958 */ 1959 mutex_lock(&kprobe_mutex); 1960 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 1961 head = &kprobe_table[i]; 1962 hlist_for_each_entry_rcu(p, node, head, hlist) 1963 if (within_module_init((unsigned long)p->addr, mod) || 1964 (checkcore && 1965 within_module_core((unsigned long)p->addr, mod))) { 1966 /* 1967 * The vaddr this probe is installed will soon 1968 * be vfreed buy not synced to disk. Hence, 1969 * disarming the breakpoint isn't needed. 1970 */ 1971 kill_kprobe(p); 1972 } 1973 } 1974 mutex_unlock(&kprobe_mutex); 1975 return NOTIFY_DONE; 1976} 1977 1978static struct notifier_block kprobe_module_nb = { 1979 .notifier_call = kprobes_module_callback, 1980 .priority = 0 1981}; 1982 1983static int __init init_kprobes(void) 1984{ 1985 int i, err = 0; 1986 unsigned long offset = 0, size = 0; 1987 char *modname, namebuf[128]; 1988 const char *symbol_name; 1989 void *addr; 1990 struct kprobe_blackpoint *kb; 1991 1992 /* FIXME allocate the probe table, currently defined statically */ 1993 /* initialize all list heads */ 1994 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 1995 INIT_HLIST_HEAD(&kprobe_table[i]); 1996 INIT_HLIST_HEAD(&kretprobe_inst_table[i]); 1997 raw_spin_lock_init(&(kretprobe_table_locks[i].lock)); 1998 } 1999 2000 /* 2001 * Lookup and populate the kprobe_blacklist. 2002 * 2003 * Unlike the kretprobe blacklist, we'll need to determine 2004 * the range of addresses that belong to the said functions, 2005 * since a kprobe need not necessarily be at the beginning 2006 * of a function. 2007 */ 2008 for (kb = kprobe_blacklist; kb->name != NULL; kb++) { 2009 kprobe_lookup_name(kb->name, addr); 2010 if (!addr) 2011 continue; 2012 2013 kb->start_addr = (unsigned long)addr; 2014 symbol_name = kallsyms_lookup(kb->start_addr, 2015 &size, &offset, &modname, namebuf); 2016 if (!symbol_name) 2017 kb->range = 0; 2018 else 2019 kb->range = size; 2020 } 2021 2022 if (kretprobe_blacklist_size) { 2023 /* lookup the function address from its name */ 2024 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { 2025 kprobe_lookup_name(kretprobe_blacklist[i].name, 2026 kretprobe_blacklist[i].addr); 2027 if (!kretprobe_blacklist[i].addr) 2028 printk("kretprobe: lookup failed: %s\n", 2029 kretprobe_blacklist[i].name); 2030 } 2031 } 2032 2033#if defined(CONFIG_OPTPROBES) 2034#if defined(__ARCH_WANT_KPROBES_INSN_SLOT) 2035 /* Init kprobe_optinsn_slots */ 2036 kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; 2037#endif 2038 /* By default, kprobes can be optimized */ 2039 kprobes_allow_optimization = true; 2040#endif 2041 2042 /* By default, kprobes are armed */ 2043 kprobes_all_disarmed = false; 2044 2045 err = arch_init_kprobes(); 2046 if (!err) 2047 err = register_die_notifier(&kprobe_exceptions_nb); 2048 if (!err) 2049 err = register_module_notifier(&kprobe_module_nb); 2050 2051 kprobes_initialized = (err == 0); 2052 2053 if (!err) 2054 init_test_probes(); 2055 return err; 2056} 2057 2058#ifdef CONFIG_DEBUG_FS 2059static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, 2060 const char *sym, int offset, char *modname, struct kprobe *pp) 2061{ 2062 char *kprobe_type; 2063 2064 if (p->pre_handler == pre_handler_kretprobe) 2065 kprobe_type = "r"; 2066 else if (p->pre_handler == setjmp_pre_handler) 2067 kprobe_type = "j"; 2068 else 2069 kprobe_type = "k"; 2070 2071 if (sym) 2072 seq_printf(pi, "%p %s %s+0x%x %s ", 2073 p->addr, kprobe_type, sym, offset, 2074 (modname ? modname : " ")); 2075 else 2076 seq_printf(pi, "%p %s %p ", 2077 p->addr, kprobe_type, p->addr); 2078 2079 if (!pp) 2080 pp = p; 2081 seq_printf(pi, "%s%s%s\n", 2082 (kprobe_gone(p) ? "[GONE]" : ""), 2083 ((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""), 2084 (kprobe_optimized(pp) ? "[OPTIMIZED]" : "")); 2085} 2086 2087static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) 2088{ 2089 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL; 2090} 2091 2092static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) 2093{ 2094 (*pos)++; 2095 if (*pos >= KPROBE_TABLE_SIZE) 2096 return NULL; 2097 return pos; 2098} 2099 2100static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v) 2101{ 2102 /* Nothing to do */ 2103} 2104 2105static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) 2106{ 2107 struct hlist_head *head; 2108 struct hlist_node *node; 2109 struct kprobe *p, *kp; 2110 const char *sym = NULL; 2111 unsigned int i = *(loff_t *) v; 2112 unsigned long offset = 0; 2113 char *modname, namebuf[128]; 2114 2115 head = &kprobe_table[i]; 2116 preempt_disable(); 2117 hlist_for_each_entry_rcu(p, node, head, hlist) { 2118 sym = kallsyms_lookup((unsigned long)p->addr, NULL, 2119 &offset, &modname, namebuf); 2120 if (kprobe_aggrprobe(p)) { 2121 list_for_each_entry_rcu(kp, &p->list, list) 2122 report_probe(pi, kp, sym, offset, modname, p); 2123 } else 2124 report_probe(pi, p, sym, offset, modname, NULL); 2125 } 2126 preempt_enable(); 2127 return 0; 2128} 2129 2130static const struct seq_operations kprobes_seq_ops = { 2131 .start = kprobe_seq_start, 2132 .next = kprobe_seq_next, 2133 .stop = kprobe_seq_stop, 2134 .show = show_kprobe_addr 2135}; 2136 2137static int __kprobes kprobes_open(struct inode *inode, struct file *filp) 2138{ 2139 return seq_open(filp, &kprobes_seq_ops); 2140} 2141 2142static const struct file_operations debugfs_kprobes_operations = { 2143 .open = kprobes_open, 2144 .read = seq_read, 2145 .llseek = seq_lseek, 2146 .release = seq_release, 2147}; 2148 2149static void __kprobes arm_all_kprobes(void) 2150{ 2151 struct hlist_head *head; 2152 struct hlist_node *node; 2153 struct kprobe *p; 2154 unsigned int i; 2155 2156 mutex_lock(&kprobe_mutex); 2157 2158 /* If kprobes are armed, just return */ 2159 if (!kprobes_all_disarmed) 2160 goto already_enabled; 2161 2162 /* Arming kprobes doesn't optimize kprobe itself */ 2163 mutex_lock(&text_mutex); 2164 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 2165 head = &kprobe_table[i]; 2166 hlist_for_each_entry_rcu(p, node, head, hlist) 2167 if (!kprobe_disabled(p)) 2168 __arm_kprobe(p); 2169 } 2170 mutex_unlock(&text_mutex); 2171 2172 kprobes_all_disarmed = false; 2173 printk(KERN_INFO "Kprobes globally enabled\n"); 2174 2175already_enabled: 2176 mutex_unlock(&kprobe_mutex); 2177 return; 2178} 2179 2180static void __kprobes disarm_all_kprobes(void) 2181{ 2182 struct hlist_head *head; 2183 struct hlist_node *node; 2184 struct kprobe *p; 2185 unsigned int i; 2186 2187 mutex_lock(&kprobe_mutex); 2188 2189 /* If kprobes are already disarmed, just return */ 2190 if (kprobes_all_disarmed) { 2191 mutex_unlock(&kprobe_mutex); 2192 return; 2193 } 2194 2195 kprobes_all_disarmed = true; 2196 printk(KERN_INFO "Kprobes globally disabled\n"); 2197 2198 mutex_lock(&text_mutex); 2199 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 2200 head = &kprobe_table[i]; 2201 hlist_for_each_entry_rcu(p, node, head, hlist) { 2202 if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) 2203 __disarm_kprobe(p, false); 2204 } 2205 } 2206 mutex_unlock(&text_mutex); 2207 mutex_unlock(&kprobe_mutex); 2208 2209 /* Wait for disarming all kprobes by optimizer */ 2210 wait_for_kprobe_optimizer(); 2211} 2212 2213/* 2214 * XXX: The debugfs bool file interface doesn't allow for callbacks 2215 * when the bool state is switched. We can reuse that facility when 2216 * available 2217 */ 2218static ssize_t read_enabled_file_bool(struct file *file, 2219 char __user *user_buf, size_t count, loff_t *ppos) 2220{ 2221 char buf[3]; 2222 2223 if (!kprobes_all_disarmed) 2224 buf[0] = '1'; 2225 else 2226 buf[0] = '0'; 2227 buf[1] = '\n'; 2228 buf[2] = 0x00; 2229 return simple_read_from_buffer(user_buf, count, ppos, buf, 2); 2230} 2231 2232static ssize_t write_enabled_file_bool(struct file *file, 2233 const char __user *user_buf, size_t count, loff_t *ppos) 2234{ 2235 char buf[32]; 2236 size_t buf_size; 2237 2238 buf_size = min(count, (sizeof(buf)-1)); 2239 if (copy_from_user(buf, user_buf, buf_size)) 2240 return -EFAULT; 2241 2242 switch (buf[0]) { 2243 case 'y': 2244 case 'Y': 2245 case '1': 2246 arm_all_kprobes(); 2247 break; 2248 case 'n': 2249 case 'N': 2250 case '0': 2251 disarm_all_kprobes(); 2252 break; 2253 } 2254 2255 return count; 2256} 2257 2258static const struct file_operations fops_kp = { 2259 .read = read_enabled_file_bool, 2260 .write = write_enabled_file_bool, 2261 .llseek = default_llseek, 2262}; 2263 2264static int __kprobes debugfs_kprobe_init(void) 2265{ 2266 struct dentry *dir, *file; 2267 unsigned int value = 1; 2268 2269 dir = debugfs_create_dir("kprobes", NULL); 2270 if (!dir) 2271 return -ENOMEM; 2272 2273 file = debugfs_create_file("list", 0444, dir, NULL, 2274 &debugfs_kprobes_operations); 2275 if (!file) { 2276 debugfs_remove(dir); 2277 return -ENOMEM; 2278 } 2279 2280 file = debugfs_create_file("enabled", 0600, dir, 2281 &value, &fops_kp); 2282 if (!file) { 2283 debugfs_remove(dir); 2284 return -ENOMEM; 2285 } 2286 2287 return 0; 2288} 2289 2290late_initcall(debugfs_kprobe_init); 2291#endif /* CONFIG_DEBUG_FS */ 2292 2293module_init(init_kprobes); 2294 2295/* defined in arch/.../kernel/kprobes.c */ 2296EXPORT_SYMBOL_GPL(jprobe_return); 2297