1 /* 2 * Kernel Probes (KProbes) 3 * kernel/kprobes.c 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 18 * 19 * Copyright (C) IBM Corporation, 2002, 2004 20 * 21 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel 22 * Probes initial implementation (includes suggestions from 23 * Rusty Russell). 24 * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with 25 * hlists and exceptions notifier as suggested by Andi Kleen. 26 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes 27 * interface to access function arguments. 28 * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes 29 * exceptions notifier to be first on the priority list. 30 * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston 31 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi 32 * <prasanna@in.ibm.com> added function-return probes. 33 */ 34 #include <linux/kprobes.h> 35 #include <linux/hash.h> 36 #include <linux/init.h> 37 #include <linux/slab.h> 38 #include <linux/stddef.h> 39 #include <linux/module.h> 40 #include <linux/moduleloader.h> 41 #include <linux/kallsyms.h> 42 #include <linux/freezer.h> 43 #include <linux/seq_file.h> 44 #include <linux/debugfs.h> 45 #include <linux/kdebug.h> 46 #include <linux/memory.h> 47 48 #include <asm-generic/sections.h> 49 #include <asm/cacheflush.h> 50 #include <asm/errno.h> 51 #include <asm/uaccess.h> 52 53 #define KPROBE_HASH_BITS 6 54 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) 55 56 57 /* 58 * Some oddball architectures like 64bit powerpc have function descriptors 59 * so this must be overridable. 60 */ 61 #ifndef kprobe_lookup_name 62 #define kprobe_lookup_name(name, addr) \ 63 addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name))) 64 #endif 65 66 static int kprobes_initialized; 67 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; 68 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; 69 70 /* NOTE: change this value only with kprobe_mutex held */ 71 static bool kprobes_all_disarmed; 72 73 static DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ 74 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; 75 static struct { 76 spinlock_t lock ____cacheline_aligned_in_smp; 77 } kretprobe_table_locks[KPROBE_TABLE_SIZE]; 78 79 static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) 80 { 81 return &(kretprobe_table_locks[hash].lock); 82 } 83 84 /* 85 * Normally, functions that we'd want to prohibit kprobes in, are marked 86 * __kprobes. But, there are cases where such functions already belong to 87 * a different section (__sched for preempt_schedule) 88 * 89 * For such cases, we now have a blacklist 90 */ 91 static struct kprobe_blackpoint kprobe_blacklist[] = { 92 {"preempt_schedule",}, 93 {NULL} /* Terminator */ 94 }; 95 96 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT 97 /* 98 * kprobe->ainsn.insn points to the copy of the instruction to be 99 * single-stepped. x86_64, POWER4 and above have no-exec support and 100 * stepping on the instruction on a vmalloced/kmalloced/data page 101 * is a recipe for disaster 102 */ 103 #define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) 104 105 struct kprobe_insn_page { 106 struct list_head list; 107 kprobe_opcode_t *insns; /* Page of instruction slots */ 108 char slot_used[INSNS_PER_PAGE]; 109 int nused; 110 int ngarbage; 111 }; 112 113 enum kprobe_slot_state { 114 SLOT_CLEAN = 0, 115 SLOT_DIRTY = 1, 116 SLOT_USED = 2, 117 }; 118 119 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */ 120 static LIST_HEAD(kprobe_insn_pages); 121 static int kprobe_garbage_slots; 122 static int collect_garbage_slots(void); 123 124 static int __kprobes check_safety(void) 125 { 126 int ret = 0; 127 #if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER) 128 ret = freeze_processes(); 129 if (ret == 0) { 130 struct task_struct *p, *q; 131 do_each_thread(p, q) { 132 if (p != current && p->state == TASK_RUNNING && 133 p->pid != 0) { 134 printk("Check failed: %s is running\n",p->comm); 135 ret = -1; 136 goto loop_end; 137 } 138 } while_each_thread(p, q); 139 } 140 loop_end: 141 thaw_processes(); 142 #else 143 synchronize_sched(); 144 #endif 145 return ret; 146 } 147 148 /** 149 * __get_insn_slot() - Find a slot on an executable page for an instruction. 150 * We allocate an executable page if there's no room on existing ones. 151 */ 152 static kprobe_opcode_t __kprobes *__get_insn_slot(void) 153 { 154 struct kprobe_insn_page *kip; 155 156 retry: 157 list_for_each_entry(kip, &kprobe_insn_pages, list) { 158 if (kip->nused < INSNS_PER_PAGE) { 159 int i; 160 for (i = 0; i < INSNS_PER_PAGE; i++) { 161 if (kip->slot_used[i] == SLOT_CLEAN) { 162 kip->slot_used[i] = SLOT_USED; 163 kip->nused++; 164 return kip->insns + (i * MAX_INSN_SIZE); 165 } 166 } 167 /* Surprise! No unused slots. Fix kip->nused. */ 168 kip->nused = INSNS_PER_PAGE; 169 } 170 } 171 172 /* If there are any garbage slots, collect it and try again. */ 173 if (kprobe_garbage_slots && collect_garbage_slots() == 0) { 174 goto retry; 175 } 176 /* All out of space. Need to allocate a new page. Use slot 0. */ 177 kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); 178 if (!kip) 179 return NULL; 180 181 /* 182 * Use module_alloc so this page is within +/- 2GB of where the 183 * kernel image and loaded module images reside. This is required 184 * so x86_64 can correctly handle the %rip-relative fixups. 185 */ 186 kip->insns = module_alloc(PAGE_SIZE); 187 if (!kip->insns) { 188 kfree(kip); 189 return NULL; 190 } 191 INIT_LIST_HEAD(&kip->list); 192 list_add(&kip->list, &kprobe_insn_pages); 193 memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE); 194 kip->slot_used[0] = SLOT_USED; 195 kip->nused = 1; 196 kip->ngarbage = 0; 197 return kip->insns; 198 } 199 200 kprobe_opcode_t __kprobes *get_insn_slot(void) 201 { 202 kprobe_opcode_t *ret; 203 mutex_lock(&kprobe_insn_mutex); 204 ret = __get_insn_slot(); 205 mutex_unlock(&kprobe_insn_mutex); 206 return ret; 207 } 208 209 /* Return 1 if all garbages are collected, otherwise 0. */ 210 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) 211 { 212 kip->slot_used[idx] = SLOT_CLEAN; 213 kip->nused--; 214 if (kip->nused == 0) { 215 /* 216 * Page is no longer in use. Free it unless 217 * it's the last one. We keep the last one 218 * so as not to have to set it up again the 219 * next time somebody inserts a probe. 220 */ 221 if (!list_is_singular(&kprobe_insn_pages)) { 222 list_del(&kip->list); 223 module_free(NULL, kip->insns); 224 kfree(kip); 225 } 226 return 1; 227 } 228 return 0; 229 } 230 231 static int __kprobes collect_garbage_slots(void) 232 { 233 struct kprobe_insn_page *kip, *next; 234 235 /* Ensure no-one is preepmted on the garbages */ 236 if (check_safety()) 237 return -EAGAIN; 238 239 list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) { 240 int i; 241 if (kip->ngarbage == 0) 242 continue; 243 kip->ngarbage = 0; /* we will collect all garbages */ 244 for (i = 0; i < INSNS_PER_PAGE; i++) { 245 if (kip->slot_used[i] == SLOT_DIRTY && 246 collect_one_slot(kip, i)) 247 break; 248 } 249 } 250 kprobe_garbage_slots = 0; 251 return 0; 252 } 253 254 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) 255 { 256 struct kprobe_insn_page *kip; 257 258 mutex_lock(&kprobe_insn_mutex); 259 list_for_each_entry(kip, &kprobe_insn_pages, list) { 260 if (kip->insns <= slot && 261 slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { 262 int i = (slot - kip->insns) / MAX_INSN_SIZE; 263 if (dirty) { 264 kip->slot_used[i] = SLOT_DIRTY; 265 kip->ngarbage++; 266 } else 267 collect_one_slot(kip, i); 268 break; 269 } 270 } 271 272 if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE) 273 collect_garbage_slots(); 274 275 mutex_unlock(&kprobe_insn_mutex); 276 } 277 #endif 278 279 /* We have preemption disabled.. so it is safe to use __ versions */ 280 static inline void set_kprobe_instance(struct kprobe *kp) 281 { 282 __get_cpu_var(kprobe_instance) = kp; 283 } 284 285 static inline void reset_kprobe_instance(void) 286 { 287 __get_cpu_var(kprobe_instance) = NULL; 288 } 289 290 /* 291 * This routine is called either: 292 * - under the kprobe_mutex - during kprobe_[un]register() 293 * OR 294 * - with preemption disabled - from arch/xxx/kernel/kprobes.c 295 */ 296 struct kprobe __kprobes *get_kprobe(void *addr) 297 { 298 struct hlist_head *head; 299 struct hlist_node *node; 300 struct kprobe *p; 301 302 head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; 303 hlist_for_each_entry_rcu(p, node, head, hlist) { 304 if (p->addr == addr) 305 return p; 306 } 307 return NULL; 308 } 309 310 /* Arm a kprobe with text_mutex */ 311 static void __kprobes arm_kprobe(struct kprobe *kp) 312 { 313 mutex_lock(&text_mutex); 314 arch_arm_kprobe(kp); 315 mutex_unlock(&text_mutex); 316 } 317 318 /* Disarm a kprobe with text_mutex */ 319 static void __kprobes disarm_kprobe(struct kprobe *kp) 320 { 321 mutex_lock(&text_mutex); 322 arch_disarm_kprobe(kp); 323 mutex_unlock(&text_mutex); 324 } 325 326 /* 327 * Aggregate handlers for multiple kprobes support - these handlers 328 * take care of invoking the individual kprobe handlers on p->list 329 */ 330 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) 331 { 332 struct kprobe *kp; 333 334 list_for_each_entry_rcu(kp, &p->list, list) { 335 if (kp->pre_handler && likely(!kprobe_disabled(kp))) { 336 set_kprobe_instance(kp); 337 if (kp->pre_handler(kp, regs)) 338 return 1; 339 } 340 reset_kprobe_instance(); 341 } 342 return 0; 343 } 344 345 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, 346 unsigned long flags) 347 { 348 struct kprobe *kp; 349 350 list_for_each_entry_rcu(kp, &p->list, list) { 351 if (kp->post_handler && likely(!kprobe_disabled(kp))) { 352 set_kprobe_instance(kp); 353 kp->post_handler(kp, regs, flags); 354 reset_kprobe_instance(); 355 } 356 } 357 } 358 359 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, 360 int trapnr) 361 { 362 struct kprobe *cur = __get_cpu_var(kprobe_instance); 363 364 /* 365 * if we faulted "during" the execution of a user specified 366 * probe handler, invoke just that probe's fault handler 367 */ 368 if (cur && cur->fault_handler) { 369 if (cur->fault_handler(cur, regs, trapnr)) 370 return 1; 371 } 372 return 0; 373 } 374 375 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) 376 { 377 struct kprobe *cur = __get_cpu_var(kprobe_instance); 378 int ret = 0; 379 380 if (cur && cur->break_handler) { 381 if (cur->break_handler(cur, regs)) 382 ret = 1; 383 } 384 reset_kprobe_instance(); 385 return ret; 386 } 387 388 /* Walks the list and increments nmissed count for multiprobe case */ 389 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) 390 { 391 struct kprobe *kp; 392 if (p->pre_handler != aggr_pre_handler) { 393 p->nmissed++; 394 } else { 395 list_for_each_entry_rcu(kp, &p->list, list) 396 kp->nmissed++; 397 } 398 return; 399 } 400 401 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, 402 struct hlist_head *head) 403 { 404 struct kretprobe *rp = ri->rp; 405 406 /* remove rp inst off the rprobe_inst_table */ 407 hlist_del(&ri->hlist); 408 INIT_HLIST_NODE(&ri->hlist); 409 if (likely(rp)) { 410 spin_lock(&rp->lock); 411 hlist_add_head(&ri->hlist, &rp->free_instances); 412 spin_unlock(&rp->lock); 413 } else 414 /* Unregistering */ 415 hlist_add_head(&ri->hlist, head); 416 } 417 418 void __kprobes kretprobe_hash_lock(struct task_struct *tsk, 419 struct hlist_head **head, unsigned long *flags) 420 { 421 unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); 422 spinlock_t *hlist_lock; 423 424 *head = &kretprobe_inst_table[hash]; 425 hlist_lock = kretprobe_table_lock_ptr(hash); 426 spin_lock_irqsave(hlist_lock, *flags); 427 } 428 429 static void __kprobes kretprobe_table_lock(unsigned long hash, 430 unsigned long *flags) 431 { 432 spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); 433 spin_lock_irqsave(hlist_lock, *flags); 434 } 435 436 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk, 437 unsigned long *flags) 438 { 439 unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); 440 spinlock_t *hlist_lock; 441 442 hlist_lock = kretprobe_table_lock_ptr(hash); 443 spin_unlock_irqrestore(hlist_lock, *flags); 444 } 445 446 void __kprobes kretprobe_table_unlock(unsigned long hash, unsigned long *flags) 447 { 448 spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); 449 spin_unlock_irqrestore(hlist_lock, *flags); 450 } 451 452 /* 453 * This function is called from finish_task_switch when task tk becomes dead, 454 * so that we can recycle any function-return probe instances associated 455 * with this task. These left over instances represent probed functions 456 * that have been called but will never return. 457 */ 458 void __kprobes kprobe_flush_task(struct task_struct *tk) 459 { 460 struct kretprobe_instance *ri; 461 struct hlist_head *head, empty_rp; 462 struct hlist_node *node, *tmp; 463 unsigned long hash, flags = 0; 464 465 if (unlikely(!kprobes_initialized)) 466 /* Early boot. kretprobe_table_locks not yet initialized. */ 467 return; 468 469 hash = hash_ptr(tk, KPROBE_HASH_BITS); 470 head = &kretprobe_inst_table[hash]; 471 kretprobe_table_lock(hash, &flags); 472 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { 473 if (ri->task == tk) 474 recycle_rp_inst(ri, &empty_rp); 475 } 476 kretprobe_table_unlock(hash, &flags); 477 INIT_HLIST_HEAD(&empty_rp); 478 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { 479 hlist_del(&ri->hlist); 480 kfree(ri); 481 } 482 } 483 484 static inline void free_rp_inst(struct kretprobe *rp) 485 { 486 struct kretprobe_instance *ri; 487 struct hlist_node *pos, *next; 488 489 hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) { 490 hlist_del(&ri->hlist); 491 kfree(ri); 492 } 493 } 494 495 static void __kprobes cleanup_rp_inst(struct kretprobe *rp) 496 { 497 unsigned long flags, hash; 498 struct kretprobe_instance *ri; 499 struct hlist_node *pos, *next; 500 struct hlist_head *head; 501 502 /* No race here */ 503 for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) { 504 kretprobe_table_lock(hash, &flags); 505 head = &kretprobe_inst_table[hash]; 506 hlist_for_each_entry_safe(ri, pos, next, head, hlist) { 507 if (ri->rp == rp) 508 ri->rp = NULL; 509 } 510 kretprobe_table_unlock(hash, &flags); 511 } 512 free_rp_inst(rp); 513 } 514 515 /* 516 * Keep all fields in the kprobe consistent 517 */ 518 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) 519 { 520 memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t)); 521 memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn)); 522 } 523 524 /* 525 * Add the new probe to ap->list. Fail if this is the 526 * second jprobe at the address - two jprobes can't coexist 527 */ 528 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p) 529 { 530 BUG_ON(kprobe_gone(ap) || kprobe_gone(p)); 531 if (p->break_handler) { 532 if (ap->break_handler) 533 return -EEXIST; 534 list_add_tail_rcu(&p->list, &ap->list); 535 ap->break_handler = aggr_break_handler; 536 } else 537 list_add_rcu(&p->list, &ap->list); 538 if (p->post_handler && !ap->post_handler) 539 ap->post_handler = aggr_post_handler; 540 541 if (kprobe_disabled(ap) && !kprobe_disabled(p)) { 542 ap->flags &= ~KPROBE_FLAG_DISABLED; 543 if (!kprobes_all_disarmed) 544 /* Arm the breakpoint again. */ 545 arm_kprobe(ap); 546 } 547 return 0; 548 } 549 550 /* 551 * Fill in the required fields of the "manager kprobe". Replace the 552 * earlier kprobe in the hlist with the manager kprobe 553 */ 554 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) 555 { 556 copy_kprobe(p, ap); 557 flush_insn_slot(ap); 558 ap->addr = p->addr; 559 ap->flags = p->flags; 560 ap->pre_handler = aggr_pre_handler; 561 ap->fault_handler = aggr_fault_handler; 562 /* We don't care the kprobe which has gone. */ 563 if (p->post_handler && !kprobe_gone(p)) 564 ap->post_handler = aggr_post_handler; 565 if (p->break_handler && !kprobe_gone(p)) 566 ap->break_handler = aggr_break_handler; 567 568 INIT_LIST_HEAD(&ap->list); 569 list_add_rcu(&p->list, &ap->list); 570 571 hlist_replace_rcu(&p->hlist, &ap->hlist); 572 } 573 574 /* 575 * This is the second or subsequent kprobe at the address - handle 576 * the intricacies 577 */ 578 static int __kprobes register_aggr_kprobe(struct kprobe *old_p, 579 struct kprobe *p) 580 { 581 int ret = 0; 582 struct kprobe *ap = old_p; 583 584 if (old_p->pre_handler != aggr_pre_handler) { 585 /* If old_p is not an aggr_probe, create new aggr_kprobe. */ 586 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL); 587 if (!ap) 588 return -ENOMEM; 589 add_aggr_kprobe(ap, old_p); 590 } 591 592 if (kprobe_gone(ap)) { 593 /* 594 * Attempting to insert new probe at the same location that 595 * had a probe in the module vaddr area which already 596 * freed. So, the instruction slot has already been 597 * released. We need a new slot for the new probe. 598 */ 599 ret = arch_prepare_kprobe(ap); 600 if (ret) 601 /* 602 * Even if fail to allocate new slot, don't need to 603 * free aggr_probe. It will be used next time, or 604 * freed by unregister_kprobe. 605 */ 606 return ret; 607 608 /* 609 * Clear gone flag to prevent allocating new slot again, and 610 * set disabled flag because it is not armed yet. 611 */ 612 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE) 613 | KPROBE_FLAG_DISABLED; 614 } 615 616 copy_kprobe(ap, p); 617 return add_new_kprobe(ap, p); 618 } 619 620 /* Try to disable aggr_kprobe, and return 1 if succeeded.*/ 621 static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p) 622 { 623 struct kprobe *kp; 624 625 list_for_each_entry_rcu(kp, &p->list, list) { 626 if (!kprobe_disabled(kp)) 627 /* 628 * There is an active probe on the list. 629 * We can't disable aggr_kprobe. 630 */ 631 return 0; 632 } 633 p->flags |= KPROBE_FLAG_DISABLED; 634 return 1; 635 } 636 637 static int __kprobes in_kprobes_functions(unsigned long addr) 638 { 639 struct kprobe_blackpoint *kb; 640 641 if (addr >= (unsigned long)__kprobes_text_start && 642 addr < (unsigned long)__kprobes_text_end) 643 return -EINVAL; 644 /* 645 * If there exists a kprobe_blacklist, verify and 646 * fail any probe registration in the prohibited area 647 */ 648 for (kb = kprobe_blacklist; kb->name != NULL; kb++) { 649 if (kb->start_addr) { 650 if (addr >= kb->start_addr && 651 addr < (kb->start_addr + kb->range)) 652 return -EINVAL; 653 } 654 } 655 return 0; 656 } 657 658 /* 659 * If we have a symbol_name argument, look it up and add the offset field 660 * to it. This way, we can specify a relative address to a symbol. 661 */ 662 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p) 663 { 664 kprobe_opcode_t *addr = p->addr; 665 if (p->symbol_name) { 666 if (addr) 667 return NULL; 668 kprobe_lookup_name(p->symbol_name, addr); 669 } 670 671 if (!addr) 672 return NULL; 673 return (kprobe_opcode_t *)(((char *)addr) + p->offset); 674 } 675 676 int __kprobes register_kprobe(struct kprobe *p) 677 { 678 int ret = 0; 679 struct kprobe *old_p; 680 struct module *probed_mod; 681 kprobe_opcode_t *addr; 682 683 addr = kprobe_addr(p); 684 if (!addr) 685 return -EINVAL; 686 p->addr = addr; 687 688 preempt_disable(); 689 if (!kernel_text_address((unsigned long) p->addr) || 690 in_kprobes_functions((unsigned long) p->addr)) { 691 preempt_enable(); 692 return -EINVAL; 693 } 694 695 /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ 696 p->flags &= KPROBE_FLAG_DISABLED; 697 698 /* 699 * Check if are we probing a module. 700 */ 701 probed_mod = __module_text_address((unsigned long) p->addr); 702 if (probed_mod) { 703 /* 704 * We must hold a refcount of the probed module while updating 705 * its code to prohibit unexpected unloading. 706 */ 707 if (unlikely(!try_module_get(probed_mod))) { 708 preempt_enable(); 709 return -EINVAL; 710 } 711 /* 712 * If the module freed .init.text, we couldn't insert 713 * kprobes in there. 714 */ 715 if (within_module_init((unsigned long)p->addr, probed_mod) && 716 probed_mod->state != MODULE_STATE_COMING) { 717 module_put(probed_mod); 718 preempt_enable(); 719 return -EINVAL; 720 } 721 } 722 preempt_enable(); 723 724 p->nmissed = 0; 725 INIT_LIST_HEAD(&p->list); 726 mutex_lock(&kprobe_mutex); 727 old_p = get_kprobe(p->addr); 728 if (old_p) { 729 ret = register_aggr_kprobe(old_p, p); 730 goto out; 731 } 732 733 mutex_lock(&text_mutex); 734 ret = arch_prepare_kprobe(p); 735 if (ret) 736 goto out_unlock_text; 737 738 INIT_HLIST_NODE(&p->hlist); 739 hlist_add_head_rcu(&p->hlist, 740 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); 741 742 if (!kprobes_all_disarmed && !kprobe_disabled(p)) 743 arch_arm_kprobe(p); 744 745 out_unlock_text: 746 mutex_unlock(&text_mutex); 747 out: 748 mutex_unlock(&kprobe_mutex); 749 750 if (probed_mod) 751 module_put(probed_mod); 752 753 return ret; 754 } 755 EXPORT_SYMBOL_GPL(register_kprobe); 756 757 /* Check passed kprobe is valid and return kprobe in kprobe_table. */ 758 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p) 759 { 760 struct kprobe *old_p, *list_p; 761 762 old_p = get_kprobe(p->addr); 763 if (unlikely(!old_p)) 764 return NULL; 765 766 if (p != old_p) { 767 list_for_each_entry_rcu(list_p, &old_p->list, list) 768 if (list_p == p) 769 /* kprobe p is a valid probe */ 770 goto valid; 771 return NULL; 772 } 773 valid: 774 return old_p; 775 } 776 777 /* 778 * Unregister a kprobe without a scheduler synchronization. 779 */ 780 static int __kprobes __unregister_kprobe_top(struct kprobe *p) 781 { 782 struct kprobe *old_p, *list_p; 783 784 old_p = __get_valid_kprobe(p); 785 if (old_p == NULL) 786 return -EINVAL; 787 788 if (old_p == p || 789 (old_p->pre_handler == aggr_pre_handler && 790 list_is_singular(&old_p->list))) { 791 /* 792 * Only probe on the hash list. Disarm only if kprobes are 793 * enabled and not gone - otherwise, the breakpoint would 794 * already have been removed. We save on flushing icache. 795 */ 796 if (!kprobes_all_disarmed && !kprobe_disabled(old_p)) 797 disarm_kprobe(p); 798 hlist_del_rcu(&old_p->hlist); 799 } else { 800 if (p->break_handler && !kprobe_gone(p)) 801 old_p->break_handler = NULL; 802 if (p->post_handler && !kprobe_gone(p)) { 803 list_for_each_entry_rcu(list_p, &old_p->list, list) { 804 if ((list_p != p) && (list_p->post_handler)) 805 goto noclean; 806 } 807 old_p->post_handler = NULL; 808 } 809 noclean: 810 list_del_rcu(&p->list); 811 if (!kprobe_disabled(old_p)) { 812 try_to_disable_aggr_kprobe(old_p); 813 if (!kprobes_all_disarmed && kprobe_disabled(old_p)) 814 disarm_kprobe(old_p); 815 } 816 } 817 return 0; 818 } 819 820 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p) 821 { 822 struct kprobe *old_p; 823 824 if (list_empty(&p->list)) 825 arch_remove_kprobe(p); 826 else if (list_is_singular(&p->list)) { 827 /* "p" is the last child of an aggr_kprobe */ 828 old_p = list_entry(p->list.next, struct kprobe, list); 829 list_del(&p->list); 830 arch_remove_kprobe(old_p); 831 kfree(old_p); 832 } 833 } 834 835 int __kprobes register_kprobes(struct kprobe **kps, int num) 836 { 837 int i, ret = 0; 838 839 if (num <= 0) 840 return -EINVAL; 841 for (i = 0; i < num; i++) { 842 ret = register_kprobe(kps[i]); 843 if (ret < 0) { 844 if (i > 0) 845 unregister_kprobes(kps, i); 846 break; 847 } 848 } 849 return ret; 850 } 851 EXPORT_SYMBOL_GPL(register_kprobes); 852 853 void __kprobes unregister_kprobe(struct kprobe *p) 854 { 855 unregister_kprobes(&p, 1); 856 } 857 EXPORT_SYMBOL_GPL(unregister_kprobe); 858 859 void __kprobes unregister_kprobes(struct kprobe **kps, int num) 860 { 861 int i; 862 863 if (num <= 0) 864 return; 865 mutex_lock(&kprobe_mutex); 866 for (i = 0; i < num; i++) 867 if (__unregister_kprobe_top(kps[i]) < 0) 868 kps[i]->addr = NULL; 869 mutex_unlock(&kprobe_mutex); 870 871 synchronize_sched(); 872 for (i = 0; i < num; i++) 873 if (kps[i]->addr) 874 __unregister_kprobe_bottom(kps[i]); 875 } 876 EXPORT_SYMBOL_GPL(unregister_kprobes); 877 878 static struct notifier_block kprobe_exceptions_nb = { 879 .notifier_call = kprobe_exceptions_notify, 880 .priority = 0x7fffffff /* we need to be notified first */ 881 }; 882 883 unsigned long __weak arch_deref_entry_point(void *entry) 884 { 885 return (unsigned long)entry; 886 } 887 888 int __kprobes register_jprobes(struct jprobe **jps, int num) 889 { 890 struct jprobe *jp; 891 int ret = 0, i; 892 893 if (num <= 0) 894 return -EINVAL; 895 for (i = 0; i < num; i++) { 896 unsigned long addr; 897 jp = jps[i]; 898 addr = arch_deref_entry_point(jp->entry); 899 900 if (!kernel_text_address(addr)) 901 ret = -EINVAL; 902 else { 903 /* Todo: Verify probepoint is a function entry point */ 904 jp->kp.pre_handler = setjmp_pre_handler; 905 jp->kp.break_handler = longjmp_break_handler; 906 ret = register_kprobe(&jp->kp); 907 } 908 if (ret < 0) { 909 if (i > 0) 910 unregister_jprobes(jps, i); 911 break; 912 } 913 } 914 return ret; 915 } 916 EXPORT_SYMBOL_GPL(register_jprobes); 917 918 int __kprobes register_jprobe(struct jprobe *jp) 919 { 920 return register_jprobes(&jp, 1); 921 } 922 EXPORT_SYMBOL_GPL(register_jprobe); 923 924 void __kprobes unregister_jprobe(struct jprobe *jp) 925 { 926 unregister_jprobes(&jp, 1); 927 } 928 EXPORT_SYMBOL_GPL(unregister_jprobe); 929 930 void __kprobes unregister_jprobes(struct jprobe **jps, int num) 931 { 932 int i; 933 934 if (num <= 0) 935 return; 936 mutex_lock(&kprobe_mutex); 937 for (i = 0; i < num; i++) 938 if (__unregister_kprobe_top(&jps[i]->kp) < 0) 939 jps[i]->kp.addr = NULL; 940 mutex_unlock(&kprobe_mutex); 941 942 synchronize_sched(); 943 for (i = 0; i < num; i++) { 944 if (jps[i]->kp.addr) 945 __unregister_kprobe_bottom(&jps[i]->kp); 946 } 947 } 948 EXPORT_SYMBOL_GPL(unregister_jprobes); 949 950 #ifdef CONFIG_KRETPROBES 951 /* 952 * This kprobe pre_handler is registered with every kretprobe. When probe 953 * hits it will set up the return probe. 954 */ 955 static int __kprobes pre_handler_kretprobe(struct kprobe *p, 956 struct pt_regs *regs) 957 { 958 struct kretprobe *rp = container_of(p, struct kretprobe, kp); 959 unsigned long hash, flags = 0; 960 struct kretprobe_instance *ri; 961 962 /*TODO: consider to only swap the RA after the last pre_handler fired */ 963 hash = hash_ptr(current, KPROBE_HASH_BITS); 964 spin_lock_irqsave(&rp->lock, flags); 965 if (!hlist_empty(&rp->free_instances)) { 966 ri = hlist_entry(rp->free_instances.first, 967 struct kretprobe_instance, hlist); 968 hlist_del(&ri->hlist); 969 spin_unlock_irqrestore(&rp->lock, flags); 970 971 ri->rp = rp; 972 ri->task = current; 973 974 if (rp->entry_handler && rp->entry_handler(ri, regs)) 975 return 0; 976 977 arch_prepare_kretprobe(ri, regs); 978 979 /* XXX(hch): why is there no hlist_move_head? */ 980 INIT_HLIST_NODE(&ri->hlist); 981 kretprobe_table_lock(hash, &flags); 982 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]); 983 kretprobe_table_unlock(hash, &flags); 984 } else { 985 rp->nmissed++; 986 spin_unlock_irqrestore(&rp->lock, flags); 987 } 988 return 0; 989 } 990 991 int __kprobes register_kretprobe(struct kretprobe *rp) 992 { 993 int ret = 0; 994 struct kretprobe_instance *inst; 995 int i; 996 void *addr; 997 998 if (kretprobe_blacklist_size) { 999 addr = kprobe_addr(&rp->kp); 1000 if (!addr) 1001 return -EINVAL; 1002 1003 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { 1004 if (kretprobe_blacklist[i].addr == addr) 1005 return -EINVAL; 1006 } 1007 } 1008 1009 rp->kp.pre_handler = pre_handler_kretprobe; 1010 rp->kp.post_handler = NULL; 1011 rp->kp.fault_handler = NULL; 1012 rp->kp.break_handler = NULL; 1013 1014 /* Pre-allocate memory for max kretprobe instances */ 1015 if (rp->maxactive <= 0) { 1016 #ifdef CONFIG_PREEMPT 1017 rp->maxactive = max(10, 2 * NR_CPUS); 1018 #else 1019 rp->maxactive = NR_CPUS; 1020 #endif 1021 } 1022 spin_lock_init(&rp->lock); 1023 INIT_HLIST_HEAD(&rp->free_instances); 1024 for (i = 0; i < rp->maxactive; i++) { 1025 inst = kmalloc(sizeof(struct kretprobe_instance) + 1026 rp->data_size, GFP_KERNEL); 1027 if (inst == NULL) { 1028 free_rp_inst(rp); 1029 return -ENOMEM; 1030 } 1031 INIT_HLIST_NODE(&inst->hlist); 1032 hlist_add_head(&inst->hlist, &rp->free_instances); 1033 } 1034 1035 rp->nmissed = 0; 1036 /* Establish function entry probe point */ 1037 ret = register_kprobe(&rp->kp); 1038 if (ret != 0) 1039 free_rp_inst(rp); 1040 return ret; 1041 } 1042 EXPORT_SYMBOL_GPL(register_kretprobe); 1043 1044 int __kprobes register_kretprobes(struct kretprobe **rps, int num) 1045 { 1046 int ret = 0, i; 1047 1048 if (num <= 0) 1049 return -EINVAL; 1050 for (i = 0; i < num; i++) { 1051 ret = register_kretprobe(rps[i]); 1052 if (ret < 0) { 1053 if (i > 0) 1054 unregister_kretprobes(rps, i); 1055 break; 1056 } 1057 } 1058 return ret; 1059 } 1060 EXPORT_SYMBOL_GPL(register_kretprobes); 1061 1062 void __kprobes unregister_kretprobe(struct kretprobe *rp) 1063 { 1064 unregister_kretprobes(&rp, 1); 1065 } 1066 EXPORT_SYMBOL_GPL(unregister_kretprobe); 1067 1068 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) 1069 { 1070 int i; 1071 1072 if (num <= 0) 1073 return; 1074 mutex_lock(&kprobe_mutex); 1075 for (i = 0; i < num; i++) 1076 if (__unregister_kprobe_top(&rps[i]->kp) < 0) 1077 rps[i]->kp.addr = NULL; 1078 mutex_unlock(&kprobe_mutex); 1079 1080 synchronize_sched(); 1081 for (i = 0; i < num; i++) { 1082 if (rps[i]->kp.addr) { 1083 __unregister_kprobe_bottom(&rps[i]->kp); 1084 cleanup_rp_inst(rps[i]); 1085 } 1086 } 1087 } 1088 EXPORT_SYMBOL_GPL(unregister_kretprobes); 1089 1090 #else /* CONFIG_KRETPROBES */ 1091 int __kprobes register_kretprobe(struct kretprobe *rp) 1092 { 1093 return -ENOSYS; 1094 } 1095 EXPORT_SYMBOL_GPL(register_kretprobe); 1096 1097 int __kprobes register_kretprobes(struct kretprobe **rps, int num) 1098 { 1099 return -ENOSYS; 1100 } 1101 EXPORT_SYMBOL_GPL(register_kretprobes); 1102 1103 void __kprobes unregister_kretprobe(struct kretprobe *rp) 1104 { 1105 } 1106 EXPORT_SYMBOL_GPL(unregister_kretprobe); 1107 1108 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) 1109 { 1110 } 1111 EXPORT_SYMBOL_GPL(unregister_kretprobes); 1112 1113 static int __kprobes pre_handler_kretprobe(struct kprobe *p, 1114 struct pt_regs *regs) 1115 { 1116 return 0; 1117 } 1118 1119 #endif /* CONFIG_KRETPROBES */ 1120 1121 /* Set the kprobe gone and remove its instruction buffer. */ 1122 static void __kprobes kill_kprobe(struct kprobe *p) 1123 { 1124 struct kprobe *kp; 1125 1126 p->flags |= KPROBE_FLAG_GONE; 1127 if (p->pre_handler == aggr_pre_handler) { 1128 /* 1129 * If this is an aggr_kprobe, we have to list all the 1130 * chained probes and mark them GONE. 1131 */ 1132 list_for_each_entry_rcu(kp, &p->list, list) 1133 kp->flags |= KPROBE_FLAG_GONE; 1134 p->post_handler = NULL; 1135 p->break_handler = NULL; 1136 } 1137 /* 1138 * Here, we can remove insn_slot safely, because no thread calls 1139 * the original probed function (which will be freed soon) any more. 1140 */ 1141 arch_remove_kprobe(p); 1142 } 1143 1144 /* Module notifier call back, checking kprobes on the module */ 1145 static int __kprobes kprobes_module_callback(struct notifier_block *nb, 1146 unsigned long val, void *data) 1147 { 1148 struct module *mod = data; 1149 struct hlist_head *head; 1150 struct hlist_node *node; 1151 struct kprobe *p; 1152 unsigned int i; 1153 int checkcore = (val == MODULE_STATE_GOING); 1154 1155 if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE) 1156 return NOTIFY_DONE; 1157 1158 /* 1159 * When MODULE_STATE_GOING was notified, both of module .text and 1160 * .init.text sections would be freed. When MODULE_STATE_LIVE was 1161 * notified, only .init.text section would be freed. We need to 1162 * disable kprobes which have been inserted in the sections. 1163 */ 1164 mutex_lock(&kprobe_mutex); 1165 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 1166 head = &kprobe_table[i]; 1167 hlist_for_each_entry_rcu(p, node, head, hlist) 1168 if (within_module_init((unsigned long)p->addr, mod) || 1169 (checkcore && 1170 within_module_core((unsigned long)p->addr, mod))) { 1171 /* 1172 * The vaddr this probe is installed will soon 1173 * be vfreed buy not synced to disk. Hence, 1174 * disarming the breakpoint isn't needed. 1175 */ 1176 kill_kprobe(p); 1177 } 1178 } 1179 mutex_unlock(&kprobe_mutex); 1180 return NOTIFY_DONE; 1181 } 1182 1183 static struct notifier_block kprobe_module_nb = { 1184 .notifier_call = kprobes_module_callback, 1185 .priority = 0 1186 }; 1187 1188 static int __init init_kprobes(void) 1189 { 1190 int i, err = 0; 1191 unsigned long offset = 0, size = 0; 1192 char *modname, namebuf[128]; 1193 const char *symbol_name; 1194 void *addr; 1195 struct kprobe_blackpoint *kb; 1196 1197 /* FIXME allocate the probe table, currently defined statically */ 1198 /* initialize all list heads */ 1199 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 1200 INIT_HLIST_HEAD(&kprobe_table[i]); 1201 INIT_HLIST_HEAD(&kretprobe_inst_table[i]); 1202 spin_lock_init(&(kretprobe_table_locks[i].lock)); 1203 } 1204 1205 /* 1206 * Lookup and populate the kprobe_blacklist. 1207 * 1208 * Unlike the kretprobe blacklist, we'll need to determine 1209 * the range of addresses that belong to the said functions, 1210 * since a kprobe need not necessarily be at the beginning 1211 * of a function. 1212 */ 1213 for (kb = kprobe_blacklist; kb->name != NULL; kb++) { 1214 kprobe_lookup_name(kb->name, addr); 1215 if (!addr) 1216 continue; 1217 1218 kb->start_addr = (unsigned long)addr; 1219 symbol_name = kallsyms_lookup(kb->start_addr, 1220 &size, &offset, &modname, namebuf); 1221 if (!symbol_name) 1222 kb->range = 0; 1223 else 1224 kb->range = size; 1225 } 1226 1227 if (kretprobe_blacklist_size) { 1228 /* lookup the function address from its name */ 1229 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { 1230 kprobe_lookup_name(kretprobe_blacklist[i].name, 1231 kretprobe_blacklist[i].addr); 1232 if (!kretprobe_blacklist[i].addr) 1233 printk("kretprobe: lookup failed: %s\n", 1234 kretprobe_blacklist[i].name); 1235 } 1236 } 1237 1238 /* By default, kprobes are armed */ 1239 kprobes_all_disarmed = false; 1240 1241 err = arch_init_kprobes(); 1242 if (!err) 1243 err = register_die_notifier(&kprobe_exceptions_nb); 1244 if (!err) 1245 err = register_module_notifier(&kprobe_module_nb); 1246 1247 kprobes_initialized = (err == 0); 1248 1249 if (!err) 1250 init_test_probes(); 1251 return err; 1252 } 1253 1254 #ifdef CONFIG_DEBUG_FS 1255 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, 1256 const char *sym, int offset,char *modname) 1257 { 1258 char *kprobe_type; 1259 1260 if (p->pre_handler == pre_handler_kretprobe) 1261 kprobe_type = "r"; 1262 else if (p->pre_handler == setjmp_pre_handler) 1263 kprobe_type = "j"; 1264 else 1265 kprobe_type = "k"; 1266 if (sym) 1267 seq_printf(pi, "%p %s %s+0x%x %s %s%s\n", 1268 p->addr, kprobe_type, sym, offset, 1269 (modname ? modname : " "), 1270 (kprobe_gone(p) ? "[GONE]" : ""), 1271 ((kprobe_disabled(p) && !kprobe_gone(p)) ? 1272 "[DISABLED]" : "")); 1273 else 1274 seq_printf(pi, "%p %s %p %s%s\n", 1275 p->addr, kprobe_type, p->addr, 1276 (kprobe_gone(p) ? "[GONE]" : ""), 1277 ((kprobe_disabled(p) && !kprobe_gone(p)) ? 1278 "[DISABLED]" : "")); 1279 } 1280 1281 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) 1282 { 1283 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL; 1284 } 1285 1286 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) 1287 { 1288 (*pos)++; 1289 if (*pos >= KPROBE_TABLE_SIZE) 1290 return NULL; 1291 return pos; 1292 } 1293 1294 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v) 1295 { 1296 /* Nothing to do */ 1297 } 1298 1299 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) 1300 { 1301 struct hlist_head *head; 1302 struct hlist_node *node; 1303 struct kprobe *p, *kp; 1304 const char *sym = NULL; 1305 unsigned int i = *(loff_t *) v; 1306 unsigned long offset = 0; 1307 char *modname, namebuf[128]; 1308 1309 head = &kprobe_table[i]; 1310 preempt_disable(); 1311 hlist_for_each_entry_rcu(p, node, head, hlist) { 1312 sym = kallsyms_lookup((unsigned long)p->addr, NULL, 1313 &offset, &modname, namebuf); 1314 if (p->pre_handler == aggr_pre_handler) { 1315 list_for_each_entry_rcu(kp, &p->list, list) 1316 report_probe(pi, kp, sym, offset, modname); 1317 } else 1318 report_probe(pi, p, sym, offset, modname); 1319 } 1320 preempt_enable(); 1321 return 0; 1322 } 1323 1324 static const struct seq_operations kprobes_seq_ops = { 1325 .start = kprobe_seq_start, 1326 .next = kprobe_seq_next, 1327 .stop = kprobe_seq_stop, 1328 .show = show_kprobe_addr 1329 }; 1330 1331 static int __kprobes kprobes_open(struct inode *inode, struct file *filp) 1332 { 1333 return seq_open(filp, &kprobes_seq_ops); 1334 } 1335 1336 static const struct file_operations debugfs_kprobes_operations = { 1337 .open = kprobes_open, 1338 .read = seq_read, 1339 .llseek = seq_lseek, 1340 .release = seq_release, 1341 }; 1342 1343 /* Disable one kprobe */ 1344 int __kprobes disable_kprobe(struct kprobe *kp) 1345 { 1346 int ret = 0; 1347 struct kprobe *p; 1348 1349 mutex_lock(&kprobe_mutex); 1350 1351 /* Check whether specified probe is valid. */ 1352 p = __get_valid_kprobe(kp); 1353 if (unlikely(p == NULL)) { 1354 ret = -EINVAL; 1355 goto out; 1356 } 1357 1358 /* If the probe is already disabled (or gone), just return */ 1359 if (kprobe_disabled(kp)) 1360 goto out; 1361 1362 kp->flags |= KPROBE_FLAG_DISABLED; 1363 if (p != kp) 1364 /* When kp != p, p is always enabled. */ 1365 try_to_disable_aggr_kprobe(p); 1366 1367 if (!kprobes_all_disarmed && kprobe_disabled(p)) 1368 disarm_kprobe(p); 1369 out: 1370 mutex_unlock(&kprobe_mutex); 1371 return ret; 1372 } 1373 EXPORT_SYMBOL_GPL(disable_kprobe); 1374 1375 /* Enable one kprobe */ 1376 int __kprobes enable_kprobe(struct kprobe *kp) 1377 { 1378 int ret = 0; 1379 struct kprobe *p; 1380 1381 mutex_lock(&kprobe_mutex); 1382 1383 /* Check whether specified probe is valid. */ 1384 p = __get_valid_kprobe(kp); 1385 if (unlikely(p == NULL)) { 1386 ret = -EINVAL; 1387 goto out; 1388 } 1389 1390 if (kprobe_gone(kp)) { 1391 /* This kprobe has gone, we couldn't enable it. */ 1392 ret = -EINVAL; 1393 goto out; 1394 } 1395 1396 if (!kprobes_all_disarmed && kprobe_disabled(p)) 1397 arm_kprobe(p); 1398 1399 p->flags &= ~KPROBE_FLAG_DISABLED; 1400 if (p != kp) 1401 kp->flags &= ~KPROBE_FLAG_DISABLED; 1402 out: 1403 mutex_unlock(&kprobe_mutex); 1404 return ret; 1405 } 1406 EXPORT_SYMBOL_GPL(enable_kprobe); 1407 1408 static void __kprobes arm_all_kprobes(void) 1409 { 1410 struct hlist_head *head; 1411 struct hlist_node *node; 1412 struct kprobe *p; 1413 unsigned int i; 1414 1415 mutex_lock(&kprobe_mutex); 1416 1417 /* If kprobes are armed, just return */ 1418 if (!kprobes_all_disarmed) 1419 goto already_enabled; 1420 1421 mutex_lock(&text_mutex); 1422 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 1423 head = &kprobe_table[i]; 1424 hlist_for_each_entry_rcu(p, node, head, hlist) 1425 if (!kprobe_disabled(p)) 1426 arch_arm_kprobe(p); 1427 } 1428 mutex_unlock(&text_mutex); 1429 1430 kprobes_all_disarmed = false; 1431 printk(KERN_INFO "Kprobes globally enabled\n"); 1432 1433 already_enabled: 1434 mutex_unlock(&kprobe_mutex); 1435 return; 1436 } 1437 1438 static void __kprobes disarm_all_kprobes(void) 1439 { 1440 struct hlist_head *head; 1441 struct hlist_node *node; 1442 struct kprobe *p; 1443 unsigned int i; 1444 1445 mutex_lock(&kprobe_mutex); 1446 1447 /* If kprobes are already disarmed, just return */ 1448 if (kprobes_all_disarmed) 1449 goto already_disabled; 1450 1451 kprobes_all_disarmed = true; 1452 printk(KERN_INFO "Kprobes globally disabled\n"); 1453 mutex_lock(&text_mutex); 1454 for (i = 0; i < KPROBE_TABLE_SIZE; i++) { 1455 head = &kprobe_table[i]; 1456 hlist_for_each_entry_rcu(p, node, head, hlist) { 1457 if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) 1458 arch_disarm_kprobe(p); 1459 } 1460 } 1461 1462 mutex_unlock(&text_mutex); 1463 mutex_unlock(&kprobe_mutex); 1464 /* Allow all currently running kprobes to complete */ 1465 synchronize_sched(); 1466 return; 1467 1468 already_disabled: 1469 mutex_unlock(&kprobe_mutex); 1470 return; 1471 } 1472 1473 /* 1474 * XXX: The debugfs bool file interface doesn't allow for callbacks 1475 * when the bool state is switched. We can reuse that facility when 1476 * available 1477 */ 1478 static ssize_t read_enabled_file_bool(struct file *file, 1479 char __user *user_buf, size_t count, loff_t *ppos) 1480 { 1481 char buf[3]; 1482 1483 if (!kprobes_all_disarmed) 1484 buf[0] = '1'; 1485 else 1486 buf[0] = '0'; 1487 buf[1] = '\n'; 1488 buf[2] = 0x00; 1489 return simple_read_from_buffer(user_buf, count, ppos, buf, 2); 1490 } 1491 1492 static ssize_t write_enabled_file_bool(struct file *file, 1493 const char __user *user_buf, size_t count, loff_t *ppos) 1494 { 1495 char buf[32]; 1496 int buf_size; 1497 1498 buf_size = min(count, (sizeof(buf)-1)); 1499 if (copy_from_user(buf, user_buf, buf_size)) 1500 return -EFAULT; 1501 1502 switch (buf[0]) { 1503 case 'y': 1504 case 'Y': 1505 case '1': 1506 arm_all_kprobes(); 1507 break; 1508 case 'n': 1509 case 'N': 1510 case '0': 1511 disarm_all_kprobes(); 1512 break; 1513 } 1514 1515 return count; 1516 } 1517 1518 static const struct file_operations fops_kp = { 1519 .read = read_enabled_file_bool, 1520 .write = write_enabled_file_bool, 1521 }; 1522 1523 static int __kprobes debugfs_kprobe_init(void) 1524 { 1525 struct dentry *dir, *file; 1526 unsigned int value = 1; 1527 1528 dir = debugfs_create_dir("kprobes", NULL); 1529 if (!dir) 1530 return -ENOMEM; 1531 1532 file = debugfs_create_file("list", 0444, dir, NULL, 1533 &debugfs_kprobes_operations); 1534 if (!file) { 1535 debugfs_remove(dir); 1536 return -ENOMEM; 1537 } 1538 1539 file = debugfs_create_file("enabled", 0600, dir, 1540 &value, &fops_kp); 1541 if (!file) { 1542 debugfs_remove(dir); 1543 return -ENOMEM; 1544 } 1545 1546 return 0; 1547 } 1548 1549 late_initcall(debugfs_kprobe_init); 1550 #endif /* CONFIG_DEBUG_FS */ 1551 1552 module_init(init_kprobes); 1553 1554 /* defined in arch/.../kernel/kprobes.c */ 1555 EXPORT_SYMBOL_GPL(jprobe_return); 1556