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