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/sections.h>
  53#include <asm/cacheflush.h>
  54#include <asm/errno.h>
  55#include <linux/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/* Blacklist -- list of struct kprobe_blacklist_entry */
  90static LIST_HEAD(kprobe_blacklist);
 
 
 
 
 
 
 
 
 
 
 
 
 
  91
  92#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
  93/*
  94 * kprobe->ainsn.insn points to the copy of the instruction to be
  95 * single-stepped. x86_64, POWER4 and above have no-exec support and
  96 * stepping on the instruction on a vmalloced/kmalloced/data page
  97 * is a recipe for disaster
  98 */
  99struct kprobe_insn_page {
 100	struct list_head list;
 101	kprobe_opcode_t *insns;		/* Page of instruction slots */
 102	struct kprobe_insn_cache *cache;
 103	int nused;
 104	int ngarbage;
 105	char slot_used[];
 106};
 107
 108#define KPROBE_INSN_PAGE_SIZE(slots)			\
 109	(offsetof(struct kprobe_insn_page, slot_used) +	\
 110	 (sizeof(char) * (slots)))
 111
 
 
 
 
 
 
 112static int slots_per_page(struct kprobe_insn_cache *c)
 113{
 114	return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
 115}
 116
 117enum kprobe_slot_state {
 118	SLOT_CLEAN = 0,
 119	SLOT_DIRTY = 1,
 120	SLOT_USED = 2,
 121};
 122
 123static void *alloc_insn_page(void)
 124{
 125	return module_alloc(PAGE_SIZE);
 126}
 127
 128static void free_insn_page(void *page)
 129{
 130	module_memfree(page);
 131}
 132
 133struct kprobe_insn_cache kprobe_insn_slots = {
 134	.mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
 135	.alloc = alloc_insn_page,
 136	.free = free_insn_page,
 137	.pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
 138	.insn_size = MAX_INSN_SIZE,
 139	.nr_garbage = 0,
 140};
 141static int collect_garbage_slots(struct kprobe_insn_cache *c);
 142
 143/**
 144 * __get_insn_slot() - Find a slot on an executable page for an instruction.
 145 * We allocate an executable page if there's no room on existing ones.
 146 */
 147kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
 148{
 149	struct kprobe_insn_page *kip;
 150	kprobe_opcode_t *slot = NULL;
 151
 152	mutex_lock(&c->mutex);
 153 retry:
 154	list_for_each_entry(kip, &c->pages, list) {
 155		if (kip->nused < slots_per_page(c)) {
 156			int i;
 157			for (i = 0; i < slots_per_page(c); i++) {
 158				if (kip->slot_used[i] == SLOT_CLEAN) {
 159					kip->slot_used[i] = SLOT_USED;
 160					kip->nused++;
 161					slot = kip->insns + (i * c->insn_size);
 162					goto out;
 163				}
 164			}
 165			/* kip->nused is broken. Fix it. */
 166			kip->nused = slots_per_page(c);
 167			WARN_ON(1);
 168		}
 169	}
 170
 171	/* If there are any garbage slots, collect it and try again. */
 172	if (c->nr_garbage && collect_garbage_slots(c) == 0)
 173		goto retry;
 174
 175	/* All out of space.  Need to allocate a new page. */
 176	kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
 177	if (!kip)
 178		goto out;
 179
 180	/*
 181	 * Use module_alloc so this page is within +/- 2GB of where the
 182	 * kernel image and loaded module images reside. This is required
 183	 * so x86_64 can correctly handle the %rip-relative fixups.
 184	 */
 185	kip->insns = c->alloc();
 186	if (!kip->insns) {
 187		kfree(kip);
 188		goto out;
 189	}
 190	INIT_LIST_HEAD(&kip->list);
 191	memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
 192	kip->slot_used[0] = SLOT_USED;
 193	kip->nused = 1;
 194	kip->ngarbage = 0;
 195	kip->cache = c;
 196	list_add(&kip->list, &c->pages);
 197	slot = kip->insns;
 198out:
 199	mutex_unlock(&c->mutex);
 200	return slot;
 
 
 
 
 
 
 
 
 
 201}
 202
 203/* Return 1 if all garbages are collected, otherwise 0. */
 204static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
 205{
 206	kip->slot_used[idx] = SLOT_CLEAN;
 207	kip->nused--;
 208	if (kip->nused == 0) {
 209		/*
 210		 * Page is no longer in use.  Free it unless
 211		 * it's the last one.  We keep the last one
 212		 * so as not to have to set it up again the
 213		 * next time somebody inserts a probe.
 214		 */
 215		if (!list_is_singular(&kip->list)) {
 216			list_del(&kip->list);
 217			kip->cache->free(kip->insns);
 218			kfree(kip);
 219		}
 220		return 1;
 221	}
 222	return 0;
 223}
 224
 225static int collect_garbage_slots(struct kprobe_insn_cache *c)
 226{
 227	struct kprobe_insn_page *kip, *next;
 228
 229	/* Ensure no-one is interrupted on the garbages */
 230	synchronize_sched();
 231
 232	list_for_each_entry_safe(kip, next, &c->pages, list) {
 233		int i;
 234		if (kip->ngarbage == 0)
 235			continue;
 236		kip->ngarbage = 0;	/* we will collect all garbages */
 237		for (i = 0; i < slots_per_page(c); i++) {
 238			if (kip->slot_used[i] == SLOT_DIRTY &&
 239			    collect_one_slot(kip, i))
 240				break;
 241		}
 242	}
 243	c->nr_garbage = 0;
 244	return 0;
 245}
 246
 247void __free_insn_slot(struct kprobe_insn_cache *c,
 248		      kprobe_opcode_t *slot, int dirty)
 249{
 250	struct kprobe_insn_page *kip;
 251
 252	mutex_lock(&c->mutex);
 253	list_for_each_entry(kip, &c->pages, list) {
 254		long idx = ((long)slot - (long)kip->insns) /
 255				(c->insn_size * sizeof(kprobe_opcode_t));
 256		if (idx >= 0 && idx < slots_per_page(c)) {
 257			WARN_ON(kip->slot_used[idx] != SLOT_USED);
 258			if (dirty) {
 259				kip->slot_used[idx] = SLOT_DIRTY;
 260				kip->ngarbage++;
 261				if (++c->nr_garbage > slots_per_page(c))
 262					collect_garbage_slots(c);
 263			} else
 264				collect_one_slot(kip, idx);
 265			goto out;
 266		}
 267	}
 268	/* Could not free this slot. */
 269	WARN_ON(1);
 270out:
 271	mutex_unlock(&c->mutex);
 272}
 273
 
 
 
 
 
 
 274#ifdef CONFIG_OPTPROBES
 275/* For optimized_kprobe buffer */
 276struct kprobe_insn_cache kprobe_optinsn_slots = {
 277	.mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
 278	.alloc = alloc_insn_page,
 279	.free = free_insn_page,
 280	.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
 281	/* .insn_size is initialized later */
 282	.nr_garbage = 0,
 283};
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 284#endif
 285#endif
 286
 287/* We have preemption disabled.. so it is safe to use __ versions */
 288static inline void set_kprobe_instance(struct kprobe *kp)
 289{
 290	__this_cpu_write(kprobe_instance, kp);
 291}
 292
 293static inline void reset_kprobe_instance(void)
 294{
 295	__this_cpu_write(kprobe_instance, NULL);
 296}
 297
 298/*
 299 * This routine is called either:
 300 * 	- under the kprobe_mutex - during kprobe_[un]register()
 301 * 				OR
 302 * 	- with preemption disabled - from arch/xxx/kernel/kprobes.c
 303 */
 304struct kprobe *get_kprobe(void *addr)
 305{
 306	struct hlist_head *head;
 
 307	struct kprobe *p;
 308
 309	head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
 310	hlist_for_each_entry_rcu(p, head, hlist) {
 311		if (p->addr == addr)
 312			return p;
 313	}
 314
 315	return NULL;
 316}
 317NOKPROBE_SYMBOL(get_kprobe);
 318
 319static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
 320
 321/* Return true if the kprobe is an aggregator */
 322static inline int kprobe_aggrprobe(struct kprobe *p)
 323{
 324	return p->pre_handler == aggr_pre_handler;
 325}
 326
 327/* Return true(!0) if the kprobe is unused */
 328static inline int kprobe_unused(struct kprobe *p)
 329{
 330	return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
 331	       list_empty(&p->list);
 332}
 333
 334/*
 335 * Keep all fields in the kprobe consistent
 336 */
 337static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
 338{
 339	memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
 340	memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
 341}
 342
 343#ifdef CONFIG_OPTPROBES
 344/* NOTE: change this value only with kprobe_mutex held */
 345static bool kprobes_allow_optimization;
 346
 347/*
 348 * Call all pre_handler on the list, but ignores its return value.
 349 * This must be called from arch-dep optimized caller.
 350 */
 351void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
 352{
 353	struct kprobe *kp;
 354
 355	list_for_each_entry_rcu(kp, &p->list, list) {
 356		if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 357			set_kprobe_instance(kp);
 358			kp->pre_handler(kp, regs);
 359		}
 360		reset_kprobe_instance();
 361	}
 362}
 363NOKPROBE_SYMBOL(opt_pre_handler);
 364
 365/* Free optimized instructions and optimized_kprobe */
 366static void free_aggr_kprobe(struct kprobe *p)
 367{
 368	struct optimized_kprobe *op;
 369
 370	op = container_of(p, struct optimized_kprobe, kp);
 371	arch_remove_optimized_kprobe(op);
 372	arch_remove_kprobe(p);
 373	kfree(op);
 374}
 375
 376/* Return true(!0) if the kprobe is ready for optimization. */
 377static inline int kprobe_optready(struct kprobe *p)
 378{
 379	struct optimized_kprobe *op;
 380
 381	if (kprobe_aggrprobe(p)) {
 382		op = container_of(p, struct optimized_kprobe, kp);
 383		return arch_prepared_optinsn(&op->optinsn);
 384	}
 385
 386	return 0;
 387}
 388
 389/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
 390static inline int kprobe_disarmed(struct kprobe *p)
 391{
 392	struct optimized_kprobe *op;
 393
 394	/* If kprobe is not aggr/opt probe, just return kprobe is disabled */
 395	if (!kprobe_aggrprobe(p))
 396		return kprobe_disabled(p);
 397
 398	op = container_of(p, struct optimized_kprobe, kp);
 399
 400	return kprobe_disabled(p) && list_empty(&op->list);
 401}
 402
 403/* Return true(!0) if the probe is queued on (un)optimizing lists */
 404static int kprobe_queued(struct kprobe *p)
 405{
 406	struct optimized_kprobe *op;
 407
 408	if (kprobe_aggrprobe(p)) {
 409		op = container_of(p, struct optimized_kprobe, kp);
 410		if (!list_empty(&op->list))
 411			return 1;
 412	}
 413	return 0;
 414}
 415
 416/*
 417 * Return an optimized kprobe whose optimizing code replaces
 418 * instructions including addr (exclude breakpoint).
 419 */
 420static struct kprobe *get_optimized_kprobe(unsigned long addr)
 421{
 422	int i;
 423	struct kprobe *p = NULL;
 424	struct optimized_kprobe *op;
 425
 426	/* Don't check i == 0, since that is a breakpoint case. */
 427	for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
 428		p = get_kprobe((void *)(addr - i));
 429
 430	if (p && kprobe_optready(p)) {
 431		op = container_of(p, struct optimized_kprobe, kp);
 432		if (arch_within_optimized_kprobe(op, addr))
 433			return p;
 434	}
 435
 436	return NULL;
 437}
 438
 439/* Optimization staging list, protected by kprobe_mutex */
 440static LIST_HEAD(optimizing_list);
 441static LIST_HEAD(unoptimizing_list);
 442static LIST_HEAD(freeing_list);
 443
 444static void kprobe_optimizer(struct work_struct *work);
 445static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
 
 446#define OPTIMIZE_DELAY 5
 447
 448/*
 449 * Optimize (replace a breakpoint with a jump) kprobes listed on
 450 * optimizing_list.
 451 */
 452static void do_optimize_kprobes(void)
 453{
 454	/* Optimization never be done when disarmed */
 455	if (kprobes_all_disarmed || !kprobes_allow_optimization ||
 456	    list_empty(&optimizing_list))
 457		return;
 458
 459	/*
 460	 * The optimization/unoptimization refers online_cpus via
 461	 * stop_machine() and cpu-hotplug modifies online_cpus.
 462	 * And same time, text_mutex will be held in cpu-hotplug and here.
 463	 * This combination can cause a deadlock (cpu-hotplug try to lock
 464	 * text_mutex but stop_machine can not be done because online_cpus
 465	 * has been changed)
 466	 * To avoid this deadlock, we need to call get_online_cpus()
 467	 * for preventing cpu-hotplug outside of text_mutex locking.
 468	 */
 469	get_online_cpus();
 470	mutex_lock(&text_mutex);
 471	arch_optimize_kprobes(&optimizing_list);
 472	mutex_unlock(&text_mutex);
 473	put_online_cpus();
 474}
 475
 476/*
 477 * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
 478 * if need) kprobes listed on unoptimizing_list.
 479 */
 480static void do_unoptimize_kprobes(void)
 481{
 482	struct optimized_kprobe *op, *tmp;
 483
 484	/* Unoptimization must be done anytime */
 485	if (list_empty(&unoptimizing_list))
 486		return;
 487
 488	/* Ditto to do_optimize_kprobes */
 489	get_online_cpus();
 490	mutex_lock(&text_mutex);
 491	arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
 492	/* Loop free_list for disarming */
 493	list_for_each_entry_safe(op, tmp, &freeing_list, list) {
 494		/* Disarm probes if marked disabled */
 495		if (kprobe_disabled(&op->kp))
 496			arch_disarm_kprobe(&op->kp);
 497		if (kprobe_unused(&op->kp)) {
 498			/*
 499			 * Remove unused probes from hash list. After waiting
 500			 * for synchronization, these probes are reclaimed.
 501			 * (reclaiming is done by do_free_cleaned_kprobes.)
 502			 */
 503			hlist_del_rcu(&op->kp.hlist);
 504		} else
 505			list_del_init(&op->list);
 506	}
 507	mutex_unlock(&text_mutex);
 508	put_online_cpus();
 509}
 510
 511/* Reclaim all kprobes on the free_list */
 512static void do_free_cleaned_kprobes(void)
 513{
 514	struct optimized_kprobe *op, *tmp;
 515
 516	list_for_each_entry_safe(op, tmp, &freeing_list, list) {
 517		BUG_ON(!kprobe_unused(&op->kp));
 518		list_del_init(&op->list);
 519		free_aggr_kprobe(&op->kp);
 520	}
 521}
 522
 523/* Start optimizer after OPTIMIZE_DELAY passed */
 524static void kick_kprobe_optimizer(void)
 525{
 526	schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
 
 527}
 528
 529/* Kprobe jump optimizer */
 530static void kprobe_optimizer(struct work_struct *work)
 531{
 532	mutex_lock(&kprobe_mutex);
 
 533	/* Lock modules while optimizing kprobes */
 534	mutex_lock(&module_mutex);
 
 535
 536	/*
 537	 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
 538	 * kprobes before waiting for quiesence period.
 539	 */
 540	do_unoptimize_kprobes();
 541
 542	/*
 543	 * Step 2: Wait for quiesence period to ensure all running interrupts
 544	 * are done. Because optprobe may modify multiple instructions
 545	 * there is a chance that Nth instruction is interrupted. In that
 546	 * case, running interrupt can return to 2nd-Nth byte of jump
 547	 * instruction. This wait is for avoiding it.
 548	 */
 549	synchronize_sched();
 550
 551	/* Step 3: Optimize kprobes after quiesence period */
 552	do_optimize_kprobes();
 553
 554	/* Step 4: Free cleaned kprobes after quiesence period */
 555	do_free_cleaned_kprobes();
 556
 557	mutex_unlock(&module_mutex);
 558	mutex_unlock(&kprobe_mutex);
 
 559
 560	/* Step 5: Kick optimizer again if needed */
 561	if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
 562		kick_kprobe_optimizer();
 
 
 
 563}
 564
 565/* Wait for completing optimization and unoptimization */
 566static void wait_for_kprobe_optimizer(void)
 567{
 568	mutex_lock(&kprobe_mutex);
 569
 570	while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
 571		mutex_unlock(&kprobe_mutex);
 572
 573		/* this will also make optimizing_work execute immmediately */
 574		flush_delayed_work(&optimizing_work);
 575		/* @optimizing_work might not have been queued yet, relax */
 576		cpu_relax();
 577
 578		mutex_lock(&kprobe_mutex);
 579	}
 580
 581	mutex_unlock(&kprobe_mutex);
 582}
 583
 584/* Optimize kprobe if p is ready to be optimized */
 585static void optimize_kprobe(struct kprobe *p)
 586{
 587	struct optimized_kprobe *op;
 588
 589	/* Check if the kprobe is disabled or not ready for optimization. */
 590	if (!kprobe_optready(p) || !kprobes_allow_optimization ||
 591	    (kprobe_disabled(p) || kprobes_all_disarmed))
 592		return;
 593
 594	/* Both of break_handler and post_handler are not supported. */
 595	if (p->break_handler || p->post_handler)
 596		return;
 597
 598	op = container_of(p, struct optimized_kprobe, kp);
 599
 600	/* Check there is no other kprobes at the optimized instructions */
 601	if (arch_check_optimized_kprobe(op) < 0)
 602		return;
 603
 604	/* Check if it is already optimized. */
 605	if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
 606		return;
 607	op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
 608
 609	if (!list_empty(&op->list))
 610		/* This is under unoptimizing. Just dequeue the probe */
 611		list_del_init(&op->list);
 612	else {
 613		list_add(&op->list, &optimizing_list);
 614		kick_kprobe_optimizer();
 615	}
 616}
 617
 618/* Short cut to direct unoptimizing */
 619static void force_unoptimize_kprobe(struct optimized_kprobe *op)
 620{
 621	get_online_cpus();
 622	arch_unoptimize_kprobe(op);
 623	put_online_cpus();
 624	if (kprobe_disabled(&op->kp))
 625		arch_disarm_kprobe(&op->kp);
 626}
 627
 628/* Unoptimize a kprobe if p is optimized */
 629static void unoptimize_kprobe(struct kprobe *p, bool force)
 630{
 631	struct optimized_kprobe *op;
 632
 633	if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
 634		return; /* This is not an optprobe nor optimized */
 635
 636	op = container_of(p, struct optimized_kprobe, kp);
 637	if (!kprobe_optimized(p)) {
 638		/* Unoptimized or unoptimizing case */
 639		if (force && !list_empty(&op->list)) {
 640			/*
 641			 * Only if this is unoptimizing kprobe and forced,
 642			 * forcibly unoptimize it. (No need to unoptimize
 643			 * unoptimized kprobe again :)
 644			 */
 645			list_del_init(&op->list);
 646			force_unoptimize_kprobe(op);
 647		}
 648		return;
 649	}
 650
 651	op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 652	if (!list_empty(&op->list)) {
 653		/* Dequeue from the optimization queue */
 654		list_del_init(&op->list);
 655		return;
 656	}
 657	/* Optimized kprobe case */
 658	if (force)
 659		/* Forcibly update the code: this is a special case */
 660		force_unoptimize_kprobe(op);
 661	else {
 662		list_add(&op->list, &unoptimizing_list);
 663		kick_kprobe_optimizer();
 664	}
 665}
 666
 667/* Cancel unoptimizing for reusing */
 668static void reuse_unused_kprobe(struct kprobe *ap)
 669{
 670	struct optimized_kprobe *op;
 671
 672	BUG_ON(!kprobe_unused(ap));
 673	/*
 674	 * Unused kprobe MUST be on the way of delayed unoptimizing (means
 675	 * there is still a relative jump) and disabled.
 676	 */
 677	op = container_of(ap, struct optimized_kprobe, kp);
 678	if (unlikely(list_empty(&op->list)))
 679		printk(KERN_WARNING "Warning: found a stray unused "
 680			"aggrprobe@%p\n", ap->addr);
 681	/* Enable the probe again */
 682	ap->flags &= ~KPROBE_FLAG_DISABLED;
 683	/* Optimize it again (remove from op->list) */
 684	BUG_ON(!kprobe_optready(ap));
 685	optimize_kprobe(ap);
 686}
 687
 688/* Remove optimized instructions */
 689static void kill_optimized_kprobe(struct kprobe *p)
 690{
 691	struct optimized_kprobe *op;
 692
 693	op = container_of(p, struct optimized_kprobe, kp);
 694	if (!list_empty(&op->list))
 695		/* Dequeue from the (un)optimization queue */
 696		list_del_init(&op->list);
 697	op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
 698
 699	if (kprobe_unused(p)) {
 700		/* Enqueue if it is unused */
 701		list_add(&op->list, &freeing_list);
 702		/*
 703		 * Remove unused probes from the hash list. After waiting
 704		 * for synchronization, this probe is reclaimed.
 705		 * (reclaiming is done by do_free_cleaned_kprobes().)
 706		 */
 707		hlist_del_rcu(&op->kp.hlist);
 708	}
 709
 
 710	/* Don't touch the code, because it is already freed. */
 711	arch_remove_optimized_kprobe(op);
 712}
 713
 714/* Try to prepare optimized instructions */
 715static void prepare_optimized_kprobe(struct kprobe *p)
 716{
 717	struct optimized_kprobe *op;
 718
 719	op = container_of(p, struct optimized_kprobe, kp);
 720	arch_prepare_optimized_kprobe(op, p);
 721}
 722
 723/* Allocate new optimized_kprobe and try to prepare optimized instructions */
 724static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 725{
 726	struct optimized_kprobe *op;
 727
 728	op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
 729	if (!op)
 730		return NULL;
 731
 732	INIT_LIST_HEAD(&op->list);
 733	op->kp.addr = p->addr;
 734	arch_prepare_optimized_kprobe(op, p);
 735
 736	return &op->kp;
 737}
 738
 739static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
 740
 741/*
 742 * Prepare an optimized_kprobe and optimize it
 743 * NOTE: p must be a normal registered kprobe
 744 */
 745static void try_to_optimize_kprobe(struct kprobe *p)
 746{
 747	struct kprobe *ap;
 748	struct optimized_kprobe *op;
 749
 750	/* Impossible to optimize ftrace-based kprobe */
 751	if (kprobe_ftrace(p))
 752		return;
 753
 754	/* For preparing optimization, jump_label_text_reserved() is called */
 755	jump_label_lock();
 756	mutex_lock(&text_mutex);
 757
 758	ap = alloc_aggr_kprobe(p);
 759	if (!ap)
 760		goto out;
 761
 762	op = container_of(ap, struct optimized_kprobe, kp);
 763	if (!arch_prepared_optinsn(&op->optinsn)) {
 764		/* If failed to setup optimizing, fallback to kprobe */
 765		arch_remove_optimized_kprobe(op);
 766		kfree(op);
 767		goto out;
 768	}
 769
 770	init_aggr_kprobe(ap, p);
 771	optimize_kprobe(ap);	/* This just kicks optimizer thread */
 772
 773out:
 774	mutex_unlock(&text_mutex);
 775	jump_label_unlock();
 776}
 777
 778#ifdef CONFIG_SYSCTL
 779static void optimize_all_kprobes(void)
 
 780{
 781	struct hlist_head *head;
 
 782	struct kprobe *p;
 783	unsigned int i;
 784
 785	mutex_lock(&kprobe_mutex);
 786	/* If optimization is already allowed, just return */
 787	if (kprobes_allow_optimization)
 788		goto out;
 789
 790	kprobes_allow_optimization = true;
 791	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 792		head = &kprobe_table[i];
 793		hlist_for_each_entry_rcu(p, head, hlist)
 794			if (!kprobe_disabled(p))
 795				optimize_kprobe(p);
 796	}
 797	printk(KERN_INFO "Kprobes globally optimized\n");
 798out:
 799	mutex_unlock(&kprobe_mutex);
 800}
 801
 802static void unoptimize_all_kprobes(void)
 
 803{
 804	struct hlist_head *head;
 
 805	struct kprobe *p;
 806	unsigned int i;
 807
 808	mutex_lock(&kprobe_mutex);
 809	/* If optimization is already prohibited, just return */
 810	if (!kprobes_allow_optimization) {
 811		mutex_unlock(&kprobe_mutex);
 812		return;
 813	}
 814
 815	kprobes_allow_optimization = false;
 816	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 817		head = &kprobe_table[i];
 818		hlist_for_each_entry_rcu(p, head, hlist) {
 819			if (!kprobe_disabled(p))
 820				unoptimize_kprobe(p, false);
 821		}
 822	}
 823	mutex_unlock(&kprobe_mutex);
 824
 825	/* Wait for unoptimizing completion */
 826	wait_for_kprobe_optimizer();
 827	printk(KERN_INFO "Kprobes globally unoptimized\n");
 828}
 829
 830static DEFINE_MUTEX(kprobe_sysctl_mutex);
 831int sysctl_kprobes_optimization;
 832int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
 833				      void __user *buffer, size_t *length,
 834				      loff_t *ppos)
 835{
 836	int ret;
 837
 838	mutex_lock(&kprobe_sysctl_mutex);
 839	sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
 840	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
 841
 842	if (sysctl_kprobes_optimization)
 843		optimize_all_kprobes();
 844	else
 845		unoptimize_all_kprobes();
 846	mutex_unlock(&kprobe_sysctl_mutex);
 847
 848	return ret;
 849}
 850#endif /* CONFIG_SYSCTL */
 851
 852/* Put a breakpoint for a probe. Must be called with text_mutex locked */
 853static void __arm_kprobe(struct kprobe *p)
 854{
 855	struct kprobe *_p;
 856
 857	/* Check collision with other optimized kprobes */
 858	_p = get_optimized_kprobe((unsigned long)p->addr);
 859	if (unlikely(_p))
 860		/* Fallback to unoptimized kprobe */
 861		unoptimize_kprobe(_p, true);
 862
 863	arch_arm_kprobe(p);
 864	optimize_kprobe(p);	/* Try to optimize (add kprobe to a list) */
 865}
 866
 867/* Remove the breakpoint of a probe. Must be called with text_mutex locked */
 868static void __disarm_kprobe(struct kprobe *p, bool reopt)
 869{
 870	struct kprobe *_p;
 871
 872	/* Try to unoptimize */
 873	unoptimize_kprobe(p, kprobes_all_disarmed);
 874
 875	if (!kprobe_queued(p)) {
 876		arch_disarm_kprobe(p);
 877		/* If another kprobe was blocked, optimize it. */
 878		_p = get_optimized_kprobe((unsigned long)p->addr);
 879		if (unlikely(_p) && reopt)
 880			optimize_kprobe(_p);
 881	}
 882	/* TODO: reoptimize others after unoptimized this probe */
 883}
 884
 885#else /* !CONFIG_OPTPROBES */
 886
 887#define optimize_kprobe(p)			do {} while (0)
 888#define unoptimize_kprobe(p, f)			do {} while (0)
 889#define kill_optimized_kprobe(p)		do {} while (0)
 890#define prepare_optimized_kprobe(p)		do {} while (0)
 891#define try_to_optimize_kprobe(p)		do {} while (0)
 892#define __arm_kprobe(p)				arch_arm_kprobe(p)
 893#define __disarm_kprobe(p, o)			arch_disarm_kprobe(p)
 894#define kprobe_disarmed(p)			kprobe_disabled(p)
 895#define wait_for_kprobe_optimizer()		do {} while (0)
 896
 897/* There should be no unused kprobes can be reused without optimization */
 898static void reuse_unused_kprobe(struct kprobe *ap)
 899{
 900	printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
 901	BUG_ON(kprobe_unused(ap));
 902}
 903
 904static void free_aggr_kprobe(struct kprobe *p)
 905{
 906	arch_remove_kprobe(p);
 907	kfree(p);
 908}
 909
 910static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 911{
 912	return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
 913}
 914#endif /* CONFIG_OPTPROBES */
 915
 916#ifdef CONFIG_KPROBES_ON_FTRACE
 917static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
 918	.func = kprobe_ftrace_handler,
 919	.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
 920};
 921static int kprobe_ftrace_enabled;
 922
 923/* Must ensure p->addr is really on ftrace */
 924static int prepare_kprobe(struct kprobe *p)
 925{
 926	if (!kprobe_ftrace(p))
 927		return arch_prepare_kprobe(p);
 928
 929	return arch_prepare_kprobe_ftrace(p);
 930}
 931
 932/* Caller must lock kprobe_mutex */
 933static void arm_kprobe_ftrace(struct kprobe *p)
 934{
 935	int ret;
 936
 937	ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 938				   (unsigned long)p->addr, 0, 0);
 939	WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 940	kprobe_ftrace_enabled++;
 941	if (kprobe_ftrace_enabled == 1) {
 942		ret = register_ftrace_function(&kprobe_ftrace_ops);
 943		WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 944	}
 945}
 946
 947/* Caller must lock kprobe_mutex */
 948static void disarm_kprobe_ftrace(struct kprobe *p)
 949{
 950	int ret;
 951
 952	kprobe_ftrace_enabled--;
 953	if (kprobe_ftrace_enabled == 0) {
 954		ret = unregister_ftrace_function(&kprobe_ftrace_ops);
 955		WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
 956	}
 957	ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
 958			   (unsigned long)p->addr, 1, 0);
 959	WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
 960}
 961#else	/* !CONFIG_KPROBES_ON_FTRACE */
 962#define prepare_kprobe(p)	arch_prepare_kprobe(p)
 963#define arm_kprobe_ftrace(p)	do {} while (0)
 964#define disarm_kprobe_ftrace(p)	do {} while (0)
 965#endif
 966
 967/* Arm a kprobe with text_mutex */
 968static void arm_kprobe(struct kprobe *kp)
 969{
 970	if (unlikely(kprobe_ftrace(kp))) {
 971		arm_kprobe_ftrace(kp);
 972		return;
 973	}
 974	/*
 975	 * Here, since __arm_kprobe() doesn't use stop_machine(),
 976	 * this doesn't cause deadlock on text_mutex. So, we don't
 977	 * need get_online_cpus().
 978	 */
 979	mutex_lock(&text_mutex);
 980	__arm_kprobe(kp);
 981	mutex_unlock(&text_mutex);
 982}
 983
 984/* Disarm a kprobe with text_mutex */
 985static void disarm_kprobe(struct kprobe *kp, bool reopt)
 986{
 987	if (unlikely(kprobe_ftrace(kp))) {
 988		disarm_kprobe_ftrace(kp);
 989		return;
 990	}
 991	/* Ditto */
 992	mutex_lock(&text_mutex);
 993	__disarm_kprobe(kp, reopt);
 994	mutex_unlock(&text_mutex);
 995}
 996
 997/*
 998 * Aggregate handlers for multiple kprobes support - these handlers
 999 * take care of invoking the individual kprobe handlers on p->list
1000 */
1001static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1002{
1003	struct kprobe *kp;
1004
1005	list_for_each_entry_rcu(kp, &p->list, list) {
1006		if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1007			set_kprobe_instance(kp);
1008			if (kp->pre_handler(kp, regs))
1009				return 1;
1010		}
1011		reset_kprobe_instance();
1012	}
1013	return 0;
1014}
1015NOKPROBE_SYMBOL(aggr_pre_handler);
1016
1017static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1018			      unsigned long flags)
1019{
1020	struct kprobe *kp;
1021
1022	list_for_each_entry_rcu(kp, &p->list, list) {
1023		if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1024			set_kprobe_instance(kp);
1025			kp->post_handler(kp, regs, flags);
1026			reset_kprobe_instance();
1027		}
1028	}
1029}
1030NOKPROBE_SYMBOL(aggr_post_handler);
1031
1032static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1033			      int trapnr)
1034{
1035	struct kprobe *cur = __this_cpu_read(kprobe_instance);
1036
1037	/*
1038	 * if we faulted "during" the execution of a user specified
1039	 * probe handler, invoke just that probe's fault handler
1040	 */
1041	if (cur && cur->fault_handler) {
1042		if (cur->fault_handler(cur, regs, trapnr))
1043			return 1;
1044	}
1045	return 0;
1046}
1047NOKPROBE_SYMBOL(aggr_fault_handler);
1048
1049static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
1050{
1051	struct kprobe *cur = __this_cpu_read(kprobe_instance);
1052	int ret = 0;
1053
1054	if (cur && cur->break_handler) {
1055		if (cur->break_handler(cur, regs))
1056			ret = 1;
1057	}
1058	reset_kprobe_instance();
1059	return ret;
1060}
1061NOKPROBE_SYMBOL(aggr_break_handler);
1062
1063/* Walks the list and increments nmissed count for multiprobe case */
1064void kprobes_inc_nmissed_count(struct kprobe *p)
1065{
1066	struct kprobe *kp;
1067	if (!kprobe_aggrprobe(p)) {
1068		p->nmissed++;
1069	} else {
1070		list_for_each_entry_rcu(kp, &p->list, list)
1071			kp->nmissed++;
1072	}
1073	return;
1074}
1075NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
1076
1077void recycle_rp_inst(struct kretprobe_instance *ri,
1078		     struct hlist_head *head)
1079{
1080	struct kretprobe *rp = ri->rp;
1081
1082	/* remove rp inst off the rprobe_inst_table */
1083	hlist_del(&ri->hlist);
1084	INIT_HLIST_NODE(&ri->hlist);
1085	if (likely(rp)) {
1086		raw_spin_lock(&rp->lock);
1087		hlist_add_head(&ri->hlist, &rp->free_instances);
1088		raw_spin_unlock(&rp->lock);
1089	} else
1090		/* Unregistering */
1091		hlist_add_head(&ri->hlist, head);
1092}
1093NOKPROBE_SYMBOL(recycle_rp_inst);
1094
1095void kretprobe_hash_lock(struct task_struct *tsk,
1096			 struct hlist_head **head, unsigned long *flags)
1097__acquires(hlist_lock)
1098{
1099	unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1100	raw_spinlock_t *hlist_lock;
1101
1102	*head = &kretprobe_inst_table[hash];
1103	hlist_lock = kretprobe_table_lock_ptr(hash);
1104	raw_spin_lock_irqsave(hlist_lock, *flags);
1105}
1106NOKPROBE_SYMBOL(kretprobe_hash_lock);
1107
1108static void kretprobe_table_lock(unsigned long hash,
1109				 unsigned long *flags)
1110__acquires(hlist_lock)
1111{
1112	raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1113	raw_spin_lock_irqsave(hlist_lock, *flags);
1114}
1115NOKPROBE_SYMBOL(kretprobe_table_lock);
1116
1117void kretprobe_hash_unlock(struct task_struct *tsk,
1118			   unsigned long *flags)
1119__releases(hlist_lock)
1120{
1121	unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1122	raw_spinlock_t *hlist_lock;
1123
1124	hlist_lock = kretprobe_table_lock_ptr(hash);
1125	raw_spin_unlock_irqrestore(hlist_lock, *flags);
1126}
1127NOKPROBE_SYMBOL(kretprobe_hash_unlock);
1128
1129static void kretprobe_table_unlock(unsigned long hash,
1130				   unsigned long *flags)
1131__releases(hlist_lock)
1132{
1133	raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1134	raw_spin_unlock_irqrestore(hlist_lock, *flags);
1135}
1136NOKPROBE_SYMBOL(kretprobe_table_unlock);
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 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}
1169NOKPROBE_SYMBOL(kprobe_flush_task);
1170
1171static inline void free_rp_inst(struct kretprobe *rp)
1172{
1173	struct kretprobe_instance *ri;
1174	struct hlist_node *next;
1175
1176	hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1177		hlist_del(&ri->hlist);
1178		kfree(ri);
1179	}
1180}
1181
1182static void cleanup_rp_inst(struct kretprobe *rp)
1183{
1184	unsigned long flags, hash;
1185	struct kretprobe_instance *ri;
1186	struct hlist_node *next;
1187	struct hlist_head *head;
1188
1189	/* No race here */
1190	for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1191		kretprobe_table_lock(hash, &flags);
1192		head = &kretprobe_inst_table[hash];
1193		hlist_for_each_entry_safe(ri, next, head, hlist) {
1194			if (ri->rp == rp)
1195				ri->rp = NULL;
1196		}
1197		kretprobe_table_unlock(hash, &flags);
1198	}
1199	free_rp_inst(rp);
1200}
1201NOKPROBE_SYMBOL(cleanup_rp_inst);
1202
1203/*
1204* Add the new probe to ap->list. Fail if this is the
1205* second jprobe at the address - two jprobes can't coexist
1206*/
1207static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1208{
1209	BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1210
1211	if (p->break_handler || p->post_handler)
1212		unoptimize_kprobe(ap, true);	/* Fall back to normal kprobe */
1213
1214	if (p->break_handler) {
1215		if (ap->break_handler)
1216			return -EEXIST;
1217		list_add_tail_rcu(&p->list, &ap->list);
1218		ap->break_handler = aggr_break_handler;
1219	} else
1220		list_add_rcu(&p->list, &ap->list);
1221	if (p->post_handler && !ap->post_handler)
1222		ap->post_handler = aggr_post_handler;
1223
 
 
 
 
 
 
1224	return 0;
1225}
1226
1227/*
1228 * Fill in the required fields of the "manager kprobe". Replace the
1229 * earlier kprobe in the hlist with the manager kprobe
1230 */
1231static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1232{
1233	/* Copy p's insn slot to ap */
1234	copy_kprobe(p, ap);
1235	flush_insn_slot(ap);
1236	ap->addr = p->addr;
1237	ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1238	ap->pre_handler = aggr_pre_handler;
1239	ap->fault_handler = aggr_fault_handler;
1240	/* We don't care the kprobe which has gone. */
1241	if (p->post_handler && !kprobe_gone(p))
1242		ap->post_handler = aggr_post_handler;
1243	if (p->break_handler && !kprobe_gone(p))
1244		ap->break_handler = aggr_break_handler;
1245
1246	INIT_LIST_HEAD(&ap->list);
1247	INIT_HLIST_NODE(&ap->hlist);
1248
1249	list_add_rcu(&p->list, &ap->list);
1250	hlist_replace_rcu(&p->hlist, &ap->hlist);
1251}
1252
1253/*
1254 * This is the second or subsequent kprobe at the address - handle
1255 * the intricacies
1256 */
1257static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
 
1258{
1259	int ret = 0;
1260	struct kprobe *ap = orig_p;
1261
1262	/* For preparing optimization, jump_label_text_reserved() is called */
1263	jump_label_lock();
1264	/*
1265	 * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1266	 * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1267	 */
1268	get_online_cpus();
1269	mutex_lock(&text_mutex);
1270
1271	if (!kprobe_aggrprobe(orig_p)) {
1272		/* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1273		ap = alloc_aggr_kprobe(orig_p);
1274		if (!ap) {
1275			ret = -ENOMEM;
1276			goto out;
1277		}
1278		init_aggr_kprobe(ap, orig_p);
1279	} else if (kprobe_unused(ap))
1280		/* This probe is going to die. Rescue it */
1281		reuse_unused_kprobe(ap);
1282
1283	if (kprobe_gone(ap)) {
1284		/*
1285		 * Attempting to insert new probe at the same location that
1286		 * had a probe in the module vaddr area which already
1287		 * freed. So, the instruction slot has already been
1288		 * released. We need a new slot for the new probe.
1289		 */
1290		ret = arch_prepare_kprobe(ap);
1291		if (ret)
1292			/*
1293			 * Even if fail to allocate new slot, don't need to
1294			 * free aggr_probe. It will be used next time, or
1295			 * freed by unregister_kprobe.
1296			 */
1297			goto out;
1298
1299		/* Prepare optimized instructions if possible. */
1300		prepare_optimized_kprobe(ap);
1301
1302		/*
1303		 * Clear gone flag to prevent allocating new slot again, and
1304		 * set disabled flag because it is not armed yet.
1305		 */
1306		ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1307			    | KPROBE_FLAG_DISABLED;
1308	}
1309
1310	/* Copy ap's insn slot to p */
1311	copy_kprobe(ap, p);
1312	ret = add_new_kprobe(ap, p);
1313
1314out:
1315	mutex_unlock(&text_mutex);
1316	put_online_cpus();
1317	jump_label_unlock();
1318
1319	if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1320		ap->flags &= ~KPROBE_FLAG_DISABLED;
1321		if (!kprobes_all_disarmed)
1322			/* Arm the breakpoint again. */
1323			arm_kprobe(ap);
1324	}
1325	return ret;
1326}
1327
1328bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1329{
1330	/* The __kprobes marked functions and entry code must not be probed */
1331	return addr >= (unsigned long)__kprobes_text_start &&
1332	       addr < (unsigned long)__kprobes_text_end;
1333}
1334
1335bool within_kprobe_blacklist(unsigned long addr)
1336{
1337	struct kprobe_blacklist_entry *ent;
1338
1339	if (arch_within_kprobe_blacklist(addr))
1340		return true;
 
1341	/*
1342	 * If there exists a kprobe_blacklist, verify and
1343	 * fail any probe registration in the prohibited area
1344	 */
1345	list_for_each_entry(ent, &kprobe_blacklist, list) {
1346		if (addr >= ent->start_addr && addr < ent->end_addr)
1347			return true;
 
 
 
1348	}
1349
1350	return false;
1351}
1352
1353/*
1354 * If we have a symbol_name argument, look it up and add the offset field
1355 * to it. This way, we can specify a relative address to a symbol.
1356 * This returns encoded errors if it fails to look up symbol or invalid
1357 * combination of parameters.
1358 */
1359static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1360{
1361	kprobe_opcode_t *addr = p->addr;
1362
1363	if ((p->symbol_name && p->addr) ||
1364	    (!p->symbol_name && !p->addr))
1365		goto invalid;
1366
1367	if (p->symbol_name) {
1368		kprobe_lookup_name(p->symbol_name, addr);
1369		if (!addr)
1370			return ERR_PTR(-ENOENT);
1371	}
1372
1373	addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1374	if (addr)
1375		return addr;
1376
1377invalid:
1378	return ERR_PTR(-EINVAL);
1379}
1380
1381/* Check passed kprobe is valid and return kprobe in kprobe_table. */
1382static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1383{
1384	struct kprobe *ap, *list_p;
1385
1386	ap = get_kprobe(p->addr);
1387	if (unlikely(!ap))
1388		return NULL;
1389
1390	if (p != ap) {
1391		list_for_each_entry_rcu(list_p, &ap->list, list)
1392			if (list_p == p)
1393			/* kprobe p is a valid probe */
1394				goto valid;
1395		return NULL;
1396	}
1397valid:
1398	return ap;
1399}
1400
1401/* Return error if the kprobe is being re-registered */
1402static inline int check_kprobe_rereg(struct kprobe *p)
1403{
1404	int ret = 0;
1405
1406	mutex_lock(&kprobe_mutex);
1407	if (__get_valid_kprobe(p))
1408		ret = -EINVAL;
1409	mutex_unlock(&kprobe_mutex);
1410
1411	return ret;
1412}
1413
1414int __weak arch_check_ftrace_location(struct kprobe *p)
1415{
1416	unsigned long ftrace_addr;
1417
1418	ftrace_addr = ftrace_location((unsigned long)p->addr);
1419	if (ftrace_addr) {
1420#ifdef CONFIG_KPROBES_ON_FTRACE
1421		/* Given address is not on the instruction boundary */
1422		if ((unsigned long)p->addr != ftrace_addr)
1423			return -EILSEQ;
1424		p->flags |= KPROBE_FLAG_FTRACE;
1425#else	/* !CONFIG_KPROBES_ON_FTRACE */
1426		return -EINVAL;
1427#endif
1428	}
1429	return 0;
1430}
1431
1432static int check_kprobe_address_safe(struct kprobe *p,
1433				     struct module **probed_mod)
1434{
1435	int ret;
1436
1437	ret = arch_check_ftrace_location(p);
1438	if (ret)
1439		return ret;
 
1440	jump_label_lock();
1441	preempt_disable();
1442
1443	/* Ensure it is not in reserved area nor out of text */
1444	if (!kernel_text_address((unsigned long) p->addr) ||
1445	    within_kprobe_blacklist((unsigned long) p->addr) ||
1446	    jump_label_text_reserved(p->addr, p->addr)) {
1447		ret = -EINVAL;
1448		goto out;
1449	}
 
 
1450
1451	/* Check if are we probing a module */
1452	*probed_mod = __module_text_address((unsigned long) p->addr);
1453	if (*probed_mod) {
 
 
 
 
1454		/*
1455		 * We must hold a refcount of the probed module while updating
1456		 * its code to prohibit unexpected unloading.
1457		 */
1458		if (unlikely(!try_module_get(*probed_mod))) {
1459			ret = -ENOENT;
1460			goto out;
1461		}
1462
1463		/*
1464		 * If the module freed .init.text, we couldn't insert
1465		 * kprobes in there.
1466		 */
1467		if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1468		    (*probed_mod)->state != MODULE_STATE_COMING) {
1469			module_put(*probed_mod);
1470			*probed_mod = NULL;
1471			ret = -ENOENT;
1472		}
 
1473	}
1474out:
1475	preempt_enable();
1476	jump_label_unlock();
1477
1478	return ret;
1479}
1480
1481int register_kprobe(struct kprobe *p)
1482{
1483	int ret;
1484	struct kprobe *old_p;
1485	struct module *probed_mod;
1486	kprobe_opcode_t *addr;
1487
1488	/* Adjust probe address from symbol */
1489	addr = kprobe_addr(p);
1490	if (IS_ERR(addr))
1491		return PTR_ERR(addr);
1492	p->addr = addr;
1493
1494	ret = check_kprobe_rereg(p);
1495	if (ret)
1496		return ret;
1497
1498	/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1499	p->flags &= KPROBE_FLAG_DISABLED;
1500	p->nmissed = 0;
1501	INIT_LIST_HEAD(&p->list);
 
1502
1503	ret = check_kprobe_address_safe(p, &probed_mod);
1504	if (ret)
1505		return ret;
1506
1507	mutex_lock(&kprobe_mutex);
 
1508
1509	old_p = get_kprobe(p->addr);
1510	if (old_p) {
1511		/* Since this may unoptimize old_p, locking text_mutex. */
1512		ret = register_aggr_kprobe(old_p, p);
1513		goto out;
1514	}
1515
1516	mutex_lock(&text_mutex);	/* Avoiding text modification */
1517	ret = prepare_kprobe(p);
1518	mutex_unlock(&text_mutex);
1519	if (ret)
1520		goto out;
1521
1522	INIT_HLIST_NODE(&p->hlist);
1523	hlist_add_head_rcu(&p->hlist,
1524		       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1525
1526	if (!kprobes_all_disarmed && !kprobe_disabled(p))
1527		arm_kprobe(p);
1528
1529	/* Try to optimize kprobe */
1530	try_to_optimize_kprobe(p);
1531
1532out:
 
 
 
1533	mutex_unlock(&kprobe_mutex);
1534
1535	if (probed_mod)
1536		module_put(probed_mod);
1537
1538	return ret;
 
 
 
 
 
1539}
1540EXPORT_SYMBOL_GPL(register_kprobe);
1541
1542/* Check if all probes on the aggrprobe are disabled */
1543static int aggr_kprobe_disabled(struct kprobe *ap)
1544{
1545	struct kprobe *kp;
1546
1547	list_for_each_entry_rcu(kp, &ap->list, list)
1548		if (!kprobe_disabled(kp))
1549			/*
1550			 * There is an active probe on the list.
1551			 * We can't disable this ap.
1552			 */
1553			return 0;
1554
1555	return 1;
1556}
1557
1558/* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1559static struct kprobe *__disable_kprobe(struct kprobe *p)
1560{
1561	struct kprobe *orig_p;
1562
1563	/* Get an original kprobe for return */
1564	orig_p = __get_valid_kprobe(p);
1565	if (unlikely(orig_p == NULL))
1566		return NULL;
1567
1568	if (!kprobe_disabled(p)) {
1569		/* Disable probe if it is a child probe */
1570		if (p != orig_p)
1571			p->flags |= KPROBE_FLAG_DISABLED;
1572
1573		/* Try to disarm and disable this/parent probe */
1574		if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1575			/*
1576			 * If kprobes_all_disarmed is set, orig_p
1577			 * should have already been disarmed, so
1578			 * skip unneed disarming process.
1579			 */
1580			if (!kprobes_all_disarmed)
1581				disarm_kprobe(orig_p, true);
1582			orig_p->flags |= KPROBE_FLAG_DISABLED;
1583		}
1584	}
1585
1586	return orig_p;
1587}
1588
1589/*
1590 * Unregister a kprobe without a scheduler synchronization.
1591 */
1592static int __unregister_kprobe_top(struct kprobe *p)
1593{
1594	struct kprobe *ap, *list_p;
1595
1596	/* Disable kprobe. This will disarm it if needed. */
1597	ap = __disable_kprobe(p);
1598	if (ap == NULL)
1599		return -EINVAL;
1600
1601	if (ap == p)
1602		/*
1603		 * This probe is an independent(and non-optimized) kprobe
1604		 * (not an aggrprobe). Remove from the hash list.
1605		 */
1606		goto disarmed;
1607
1608	/* Following process expects this probe is an aggrprobe */
1609	WARN_ON(!kprobe_aggrprobe(ap));
1610
1611	if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1612		/*
1613		 * !disarmed could be happen if the probe is under delayed
1614		 * unoptimizing.
1615		 */
1616		goto disarmed;
1617	else {
1618		/* If disabling probe has special handlers, update aggrprobe */
1619		if (p->break_handler && !kprobe_gone(p))
1620			ap->break_handler = NULL;
1621		if (p->post_handler && !kprobe_gone(p)) {
1622			list_for_each_entry_rcu(list_p, &ap->list, list) {
1623				if ((list_p != p) && (list_p->post_handler))
1624					goto noclean;
1625			}
1626			ap->post_handler = NULL;
1627		}
1628noclean:
1629		/*
1630		 * Remove from the aggrprobe: this path will do nothing in
1631		 * __unregister_kprobe_bottom().
1632		 */
1633		list_del_rcu(&p->list);
1634		if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1635			/*
1636			 * Try to optimize this probe again, because post
1637			 * handler may have been changed.
1638			 */
1639			optimize_kprobe(ap);
1640	}
1641	return 0;
1642
1643disarmed:
1644	BUG_ON(!kprobe_disarmed(ap));
1645	hlist_del_rcu(&ap->hlist);
1646	return 0;
1647}
1648
1649static void __unregister_kprobe_bottom(struct kprobe *p)
1650{
1651	struct kprobe *ap;
1652
1653	if (list_empty(&p->list))
1654		/* This is an independent kprobe */
1655		arch_remove_kprobe(p);
1656	else if (list_is_singular(&p->list)) {
1657		/* This is the last child of an aggrprobe */
1658		ap = list_entry(p->list.next, struct kprobe, list);
1659		list_del(&p->list);
1660		free_aggr_kprobe(ap);
1661	}
1662	/* Otherwise, do nothing. */
1663}
1664
1665int register_kprobes(struct kprobe **kps, int num)
1666{
1667	int i, ret = 0;
1668
1669	if (num <= 0)
1670		return -EINVAL;
1671	for (i = 0; i < num; i++) {
1672		ret = register_kprobe(kps[i]);
1673		if (ret < 0) {
1674			if (i > 0)
1675				unregister_kprobes(kps, i);
1676			break;
1677		}
1678	}
1679	return ret;
1680}
1681EXPORT_SYMBOL_GPL(register_kprobes);
1682
1683void unregister_kprobe(struct kprobe *p)
1684{
1685	unregister_kprobes(&p, 1);
1686}
1687EXPORT_SYMBOL_GPL(unregister_kprobe);
1688
1689void unregister_kprobes(struct kprobe **kps, int num)
1690{
1691	int i;
1692
1693	if (num <= 0)
1694		return;
1695	mutex_lock(&kprobe_mutex);
1696	for (i = 0; i < num; i++)
1697		if (__unregister_kprobe_top(kps[i]) < 0)
1698			kps[i]->addr = NULL;
1699	mutex_unlock(&kprobe_mutex);
1700
1701	synchronize_sched();
1702	for (i = 0; i < num; i++)
1703		if (kps[i]->addr)
1704			__unregister_kprobe_bottom(kps[i]);
1705}
1706EXPORT_SYMBOL_GPL(unregister_kprobes);
1707
1708static struct notifier_block kprobe_exceptions_nb = {
1709	.notifier_call = kprobe_exceptions_notify,
1710	.priority = 0x7fffffff /* we need to be notified first */
1711};
1712
1713unsigned long __weak arch_deref_entry_point(void *entry)
1714{
1715	return (unsigned long)entry;
1716}
1717
1718int register_jprobes(struct jprobe **jps, int num)
1719{
1720	struct jprobe *jp;
1721	int ret = 0, i;
1722
1723	if (num <= 0)
1724		return -EINVAL;
1725	for (i = 0; i < num; i++) {
1726		unsigned long addr, offset;
1727		jp = jps[i];
1728		addr = arch_deref_entry_point(jp->entry);
1729
1730		/* Verify probepoint is a function entry point */
1731		if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1732		    offset == 0) {
1733			jp->kp.pre_handler = setjmp_pre_handler;
1734			jp->kp.break_handler = longjmp_break_handler;
1735			ret = register_kprobe(&jp->kp);
1736		} else
1737			ret = -EINVAL;
1738
1739		if (ret < 0) {
1740			if (i > 0)
1741				unregister_jprobes(jps, i);
1742			break;
1743		}
1744	}
1745	return ret;
1746}
1747EXPORT_SYMBOL_GPL(register_jprobes);
1748
1749int register_jprobe(struct jprobe *jp)
1750{
1751	return register_jprobes(&jp, 1);
1752}
1753EXPORT_SYMBOL_GPL(register_jprobe);
1754
1755void unregister_jprobe(struct jprobe *jp)
1756{
1757	unregister_jprobes(&jp, 1);
1758}
1759EXPORT_SYMBOL_GPL(unregister_jprobe);
1760
1761void unregister_jprobes(struct jprobe **jps, int num)
1762{
1763	int i;
1764
1765	if (num <= 0)
1766		return;
1767	mutex_lock(&kprobe_mutex);
1768	for (i = 0; i < num; i++)
1769		if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1770			jps[i]->kp.addr = NULL;
1771	mutex_unlock(&kprobe_mutex);
1772
1773	synchronize_sched();
1774	for (i = 0; i < num; i++) {
1775		if (jps[i]->kp.addr)
1776			__unregister_kprobe_bottom(&jps[i]->kp);
1777	}
1778}
1779EXPORT_SYMBOL_GPL(unregister_jprobes);
1780
1781#ifdef CONFIG_KRETPROBES
1782/*
1783 * This kprobe pre_handler is registered with every kretprobe. When probe
1784 * hits it will set up the return probe.
1785 */
1786static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
 
1787{
1788	struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1789	unsigned long hash, flags = 0;
1790	struct kretprobe_instance *ri;
1791
1792	/*
1793	 * To avoid deadlocks, prohibit return probing in NMI contexts,
1794	 * just skip the probe and increase the (inexact) 'nmissed'
1795	 * statistical counter, so that the user is informed that
1796	 * something happened:
1797	 */
1798	if (unlikely(in_nmi())) {
1799		rp->nmissed++;
1800		return 0;
1801	}
1802
1803	/* TODO: consider to only swap the RA after the last pre_handler fired */
1804	hash = hash_ptr(current, KPROBE_HASH_BITS);
1805	raw_spin_lock_irqsave(&rp->lock, flags);
1806	if (!hlist_empty(&rp->free_instances)) {
1807		ri = hlist_entry(rp->free_instances.first,
1808				struct kretprobe_instance, hlist);
1809		hlist_del(&ri->hlist);
1810		raw_spin_unlock_irqrestore(&rp->lock, flags);
1811
1812		ri->rp = rp;
1813		ri->task = current;
1814
1815		if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1816			raw_spin_lock_irqsave(&rp->lock, flags);
1817			hlist_add_head(&ri->hlist, &rp->free_instances);
1818			raw_spin_unlock_irqrestore(&rp->lock, flags);
1819			return 0;
1820		}
1821
1822		arch_prepare_kretprobe(ri, regs);
1823
1824		/* XXX(hch): why is there no hlist_move_head? */
1825		INIT_HLIST_NODE(&ri->hlist);
1826		kretprobe_table_lock(hash, &flags);
1827		hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1828		kretprobe_table_unlock(hash, &flags);
1829	} else {
1830		rp->nmissed++;
1831		raw_spin_unlock_irqrestore(&rp->lock, flags);
1832	}
1833	return 0;
1834}
1835NOKPROBE_SYMBOL(pre_handler_kretprobe);
1836
1837int register_kretprobe(struct kretprobe *rp)
1838{
1839	int ret = 0;
1840	struct kretprobe_instance *inst;
1841	int i;
1842	void *addr;
1843
1844	if (kretprobe_blacklist_size) {
1845		addr = kprobe_addr(&rp->kp);
1846		if (IS_ERR(addr))
1847			return PTR_ERR(addr);
1848
1849		for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1850			if (kretprobe_blacklist[i].addr == addr)
1851				return -EINVAL;
1852		}
1853	}
1854
1855	rp->kp.pre_handler = pre_handler_kretprobe;
1856	rp->kp.post_handler = NULL;
1857	rp->kp.fault_handler = NULL;
1858	rp->kp.break_handler = NULL;
1859
1860	/* Pre-allocate memory for max kretprobe instances */
1861	if (rp->maxactive <= 0) {
1862#ifdef CONFIG_PREEMPT
1863		rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1864#else
1865		rp->maxactive = num_possible_cpus();
1866#endif
1867	}
1868	raw_spin_lock_init(&rp->lock);
1869	INIT_HLIST_HEAD(&rp->free_instances);
1870	for (i = 0; i < rp->maxactive; i++) {
1871		inst = kmalloc(sizeof(struct kretprobe_instance) +
1872			       rp->data_size, GFP_KERNEL);
1873		if (inst == NULL) {
1874			free_rp_inst(rp);
1875			return -ENOMEM;
1876		}
1877		INIT_HLIST_NODE(&inst->hlist);
1878		hlist_add_head(&inst->hlist, &rp->free_instances);
1879	}
1880
1881	rp->nmissed = 0;
1882	/* Establish function entry probe point */
1883	ret = register_kprobe(&rp->kp);
1884	if (ret != 0)
1885		free_rp_inst(rp);
1886	return ret;
1887}
1888EXPORT_SYMBOL_GPL(register_kretprobe);
1889
1890int register_kretprobes(struct kretprobe **rps, int num)
1891{
1892	int ret = 0, i;
1893
1894	if (num <= 0)
1895		return -EINVAL;
1896	for (i = 0; i < num; i++) {
1897		ret = register_kretprobe(rps[i]);
1898		if (ret < 0) {
1899			if (i > 0)
1900				unregister_kretprobes(rps, i);
1901			break;
1902		}
1903	}
1904	return ret;
1905}
1906EXPORT_SYMBOL_GPL(register_kretprobes);
1907
1908void unregister_kretprobe(struct kretprobe *rp)
1909{
1910	unregister_kretprobes(&rp, 1);
1911}
1912EXPORT_SYMBOL_GPL(unregister_kretprobe);
1913
1914void unregister_kretprobes(struct kretprobe **rps, int num)
1915{
1916	int i;
1917
1918	if (num <= 0)
1919		return;
1920	mutex_lock(&kprobe_mutex);
1921	for (i = 0; i < num; i++)
1922		if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1923			rps[i]->kp.addr = NULL;
1924	mutex_unlock(&kprobe_mutex);
1925
1926	synchronize_sched();
1927	for (i = 0; i < num; i++) {
1928		if (rps[i]->kp.addr) {
1929			__unregister_kprobe_bottom(&rps[i]->kp);
1930			cleanup_rp_inst(rps[i]);
1931		}
1932	}
1933}
1934EXPORT_SYMBOL_GPL(unregister_kretprobes);
1935
1936#else /* CONFIG_KRETPROBES */
1937int register_kretprobe(struct kretprobe *rp)
1938{
1939	return -ENOSYS;
1940}
1941EXPORT_SYMBOL_GPL(register_kretprobe);
1942
1943int register_kretprobes(struct kretprobe **rps, int num)
1944{
1945	return -ENOSYS;
1946}
1947EXPORT_SYMBOL_GPL(register_kretprobes);
1948
1949void unregister_kretprobe(struct kretprobe *rp)
1950{
1951}
1952EXPORT_SYMBOL_GPL(unregister_kretprobe);
1953
1954void unregister_kretprobes(struct kretprobe **rps, int num)
1955{
1956}
1957EXPORT_SYMBOL_GPL(unregister_kretprobes);
1958
1959static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
 
1960{
1961	return 0;
1962}
1963NOKPROBE_SYMBOL(pre_handler_kretprobe);
1964
1965#endif /* CONFIG_KRETPROBES */
1966
1967/* Set the kprobe gone and remove its instruction buffer. */
1968static void kill_kprobe(struct kprobe *p)
1969{
1970	struct kprobe *kp;
1971
1972	p->flags |= KPROBE_FLAG_GONE;
1973	if (kprobe_aggrprobe(p)) {
1974		/*
1975		 * If this is an aggr_kprobe, we have to list all the
1976		 * chained probes and mark them GONE.
1977		 */
1978		list_for_each_entry_rcu(kp, &p->list, list)
1979			kp->flags |= KPROBE_FLAG_GONE;
1980		p->post_handler = NULL;
1981		p->break_handler = NULL;
1982		kill_optimized_kprobe(p);
1983	}
1984	/*
1985	 * Here, we can remove insn_slot safely, because no thread calls
1986	 * the original probed function (which will be freed soon) any more.
1987	 */
1988	arch_remove_kprobe(p);
1989}
1990
1991/* Disable one kprobe */
1992int disable_kprobe(struct kprobe *kp)
1993{
1994	int ret = 0;
1995
1996	mutex_lock(&kprobe_mutex);
1997
1998	/* Disable this kprobe */
1999	if (__disable_kprobe(kp) == NULL)
2000		ret = -EINVAL;
2001
2002	mutex_unlock(&kprobe_mutex);
2003	return ret;
2004}
2005EXPORT_SYMBOL_GPL(disable_kprobe);
2006
2007/* Enable one kprobe */
2008int enable_kprobe(struct kprobe *kp)
2009{
2010	int ret = 0;
2011	struct kprobe *p;
2012
2013	mutex_lock(&kprobe_mutex);
2014
2015	/* Check whether specified probe is valid. */
2016	p = __get_valid_kprobe(kp);
2017	if (unlikely(p == NULL)) {
2018		ret = -EINVAL;
2019		goto out;
2020	}
2021
2022	if (kprobe_gone(kp)) {
2023		/* This kprobe has gone, we couldn't enable it. */
2024		ret = -EINVAL;
2025		goto out;
2026	}
2027
2028	if (p != kp)
2029		kp->flags &= ~KPROBE_FLAG_DISABLED;
2030
2031	if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2032		p->flags &= ~KPROBE_FLAG_DISABLED;
2033		arm_kprobe(p);
2034	}
2035out:
2036	mutex_unlock(&kprobe_mutex);
2037	return ret;
2038}
2039EXPORT_SYMBOL_GPL(enable_kprobe);
2040
2041void dump_kprobe(struct kprobe *kp)
2042{
2043	printk(KERN_WARNING "Dumping kprobe:\n");
2044	printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2045	       kp->symbol_name, kp->addr, kp->offset);
2046}
2047NOKPROBE_SYMBOL(dump_kprobe);
2048
2049/*
2050 * Lookup and populate the kprobe_blacklist.
2051 *
2052 * Unlike the kretprobe blacklist, we'll need to determine
2053 * the range of addresses that belong to the said functions,
2054 * since a kprobe need not necessarily be at the beginning
2055 * of a function.
2056 */
2057static int __init populate_kprobe_blacklist(unsigned long *start,
2058					     unsigned long *end)
2059{
2060	unsigned long *iter;
2061	struct kprobe_blacklist_entry *ent;
2062	unsigned long entry, offset = 0, size = 0;
2063
2064	for (iter = start; iter < end; iter++) {
2065		entry = arch_deref_entry_point((void *)*iter);
2066
2067		if (!kernel_text_address(entry) ||
2068		    !kallsyms_lookup_size_offset(entry, &size, &offset)) {
2069			pr_err("Failed to find blacklist at %p\n",
2070				(void *)entry);
2071			continue;
2072		}
2073
2074		ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2075		if (!ent)
2076			return -ENOMEM;
2077		ent->start_addr = entry;
2078		ent->end_addr = entry + size;
2079		INIT_LIST_HEAD(&ent->list);
2080		list_add_tail(&ent->list, &kprobe_blacklist);
2081	}
2082	return 0;
2083}
2084
2085/* Module notifier call back, checking kprobes on the module */
2086static int kprobes_module_callback(struct notifier_block *nb,
2087				   unsigned long val, void *data)
2088{
2089	struct module *mod = data;
2090	struct hlist_head *head;
 
2091	struct kprobe *p;
2092	unsigned int i;
2093	int checkcore = (val == MODULE_STATE_GOING);
2094
2095	if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2096		return NOTIFY_DONE;
2097
2098	/*
2099	 * When MODULE_STATE_GOING was notified, both of module .text and
2100	 * .init.text sections would be freed. When MODULE_STATE_LIVE was
2101	 * notified, only .init.text section would be freed. We need to
2102	 * disable kprobes which have been inserted in the sections.
2103	 */
2104	mutex_lock(&kprobe_mutex);
2105	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2106		head = &kprobe_table[i];
2107		hlist_for_each_entry_rcu(p, head, hlist)
2108			if (within_module_init((unsigned long)p->addr, mod) ||
2109			    (checkcore &&
2110			     within_module_core((unsigned long)p->addr, mod))) {
2111				/*
2112				 * The vaddr this probe is installed will soon
2113				 * be vfreed buy not synced to disk. Hence,
2114				 * disarming the breakpoint isn't needed.
2115				 */
2116				kill_kprobe(p);
2117			}
2118	}
2119	mutex_unlock(&kprobe_mutex);
2120	return NOTIFY_DONE;
2121}
2122
2123static struct notifier_block kprobe_module_nb = {
2124	.notifier_call = kprobes_module_callback,
2125	.priority = 0
2126};
2127
2128/* Markers of _kprobe_blacklist section */
2129extern unsigned long __start_kprobe_blacklist[];
2130extern unsigned long __stop_kprobe_blacklist[];
2131
2132static int __init init_kprobes(void)
2133{
2134	int i, err = 0;
 
 
 
 
 
2135
2136	/* FIXME allocate the probe table, currently defined statically */
2137	/* initialize all list heads */
2138	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2139		INIT_HLIST_HEAD(&kprobe_table[i]);
2140		INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2141		raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2142	}
2143
2144	err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2145					__stop_kprobe_blacklist);
2146	if (err) {
2147		pr_err("kprobes: failed to populate blacklist: %d\n", err);
2148		pr_err("Please take care of using kprobes.\n");
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2149	}
2150
2151	if (kretprobe_blacklist_size) {
2152		/* lookup the function address from its name */
2153		for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2154			kprobe_lookup_name(kretprobe_blacklist[i].name,
2155					   kretprobe_blacklist[i].addr);
2156			if (!kretprobe_blacklist[i].addr)
2157				printk("kretprobe: lookup failed: %s\n",
2158				       kretprobe_blacklist[i].name);
2159		}
2160	}
2161
2162#if defined(CONFIG_OPTPROBES)
2163#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2164	/* Init kprobe_optinsn_slots */
2165	kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2166#endif
2167	/* By default, kprobes can be optimized */
2168	kprobes_allow_optimization = true;
2169#endif
2170
2171	/* By default, kprobes are armed */
2172	kprobes_all_disarmed = false;
2173
2174	err = arch_init_kprobes();
2175	if (!err)
2176		err = register_die_notifier(&kprobe_exceptions_nb);
2177	if (!err)
2178		err = register_module_notifier(&kprobe_module_nb);
2179
2180	kprobes_initialized = (err == 0);
2181
2182	if (!err)
2183		init_test_probes();
2184	return err;
2185}
2186
2187#ifdef CONFIG_DEBUG_FS
2188static void report_probe(struct seq_file *pi, struct kprobe *p,
2189		const char *sym, int offset, char *modname, struct kprobe *pp)
2190{
2191	char *kprobe_type;
2192
2193	if (p->pre_handler == pre_handler_kretprobe)
2194		kprobe_type = "r";
2195	else if (p->pre_handler == setjmp_pre_handler)
2196		kprobe_type = "j";
2197	else
2198		kprobe_type = "k";
2199
2200	if (sym)
2201		seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2202			p->addr, kprobe_type, sym, offset,
2203			(modname ? modname : " "));
2204	else
2205		seq_printf(pi, "%p  %s  %p ",
2206			p->addr, kprobe_type, p->addr);
2207
2208	if (!pp)
2209		pp = p;
2210	seq_printf(pi, "%s%s%s%s\n",
2211		(kprobe_gone(p) ? "[GONE]" : ""),
2212		((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2213		(kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2214		(kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2215}
2216
2217static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2218{
2219	return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2220}
2221
2222static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2223{
2224	(*pos)++;
2225	if (*pos >= KPROBE_TABLE_SIZE)
2226		return NULL;
2227	return pos;
2228}
2229
2230static void kprobe_seq_stop(struct seq_file *f, void *v)
2231{
2232	/* Nothing to do */
2233}
2234
2235static int show_kprobe_addr(struct seq_file *pi, void *v)
2236{
2237	struct hlist_head *head;
 
2238	struct kprobe *p, *kp;
2239	const char *sym = NULL;
2240	unsigned int i = *(loff_t *) v;
2241	unsigned long offset = 0;
2242	char *modname, namebuf[KSYM_NAME_LEN];
2243
2244	head = &kprobe_table[i];
2245	preempt_disable();
2246	hlist_for_each_entry_rcu(p, head, hlist) {
2247		sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2248					&offset, &modname, namebuf);
2249		if (kprobe_aggrprobe(p)) {
2250			list_for_each_entry_rcu(kp, &p->list, list)
2251				report_probe(pi, kp, sym, offset, modname, p);
2252		} else
2253			report_probe(pi, p, sym, offset, modname, NULL);
2254	}
2255	preempt_enable();
2256	return 0;
2257}
2258
2259static const struct seq_operations kprobes_seq_ops = {
2260	.start = kprobe_seq_start,
2261	.next  = kprobe_seq_next,
2262	.stop  = kprobe_seq_stop,
2263	.show  = show_kprobe_addr
2264};
2265
2266static int kprobes_open(struct inode *inode, struct file *filp)
2267{
2268	return seq_open(filp, &kprobes_seq_ops);
2269}
2270
2271static const struct file_operations debugfs_kprobes_operations = {
2272	.open           = kprobes_open,
2273	.read           = seq_read,
2274	.llseek         = seq_lseek,
2275	.release        = seq_release,
2276};
2277
2278/* kprobes/blacklist -- shows which functions can not be probed */
2279static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
2280{
2281	return seq_list_start(&kprobe_blacklist, *pos);
2282}
2283
2284static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
2285{
2286	return seq_list_next(v, &kprobe_blacklist, pos);
2287}
2288
2289static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
2290{
2291	struct kprobe_blacklist_entry *ent =
2292		list_entry(v, struct kprobe_blacklist_entry, list);
2293
2294	seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
2295		   (void *)ent->end_addr, (void *)ent->start_addr);
2296	return 0;
2297}
2298
2299static const struct seq_operations kprobe_blacklist_seq_ops = {
2300	.start = kprobe_blacklist_seq_start,
2301	.next  = kprobe_blacklist_seq_next,
2302	.stop  = kprobe_seq_stop,	/* Reuse void function */
2303	.show  = kprobe_blacklist_seq_show,
2304};
2305
2306static int kprobe_blacklist_open(struct inode *inode, struct file *filp)
2307{
2308	return seq_open(filp, &kprobe_blacklist_seq_ops);
2309}
2310
2311static const struct file_operations debugfs_kprobe_blacklist_ops = {
2312	.open           = kprobe_blacklist_open,
2313	.read           = seq_read,
2314	.llseek         = seq_lseek,
2315	.release        = seq_release,
2316};
2317
2318static void arm_all_kprobes(void)
2319{
2320	struct hlist_head *head;
 
2321	struct kprobe *p;
2322	unsigned int i;
2323
2324	mutex_lock(&kprobe_mutex);
2325
2326	/* If kprobes are armed, just return */
2327	if (!kprobes_all_disarmed)
2328		goto already_enabled;
2329
2330	/*
2331	 * optimize_kprobe() called by arm_kprobe() checks
2332	 * kprobes_all_disarmed, so set kprobes_all_disarmed before
2333	 * arm_kprobe.
2334	 */
2335	kprobes_all_disarmed = false;
2336	/* Arming kprobes doesn't optimize kprobe itself */
 
2337	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2338		head = &kprobe_table[i];
2339		hlist_for_each_entry_rcu(p, head, hlist)
2340			if (!kprobe_disabled(p))
2341				arm_kprobe(p);
2342	}
 
2343
 
2344	printk(KERN_INFO "Kprobes globally enabled\n");
2345
2346already_enabled:
2347	mutex_unlock(&kprobe_mutex);
2348	return;
2349}
2350
2351static void disarm_all_kprobes(void)
2352{
2353	struct hlist_head *head;
 
2354	struct kprobe *p;
2355	unsigned int i;
2356
2357	mutex_lock(&kprobe_mutex);
2358
2359	/* If kprobes are already disarmed, just return */
2360	if (kprobes_all_disarmed) {
2361		mutex_unlock(&kprobe_mutex);
2362		return;
2363	}
2364
2365	kprobes_all_disarmed = true;
2366	printk(KERN_INFO "Kprobes globally disabled\n");
2367
 
2368	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2369		head = &kprobe_table[i];
2370		hlist_for_each_entry_rcu(p, head, hlist) {
2371			if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2372				disarm_kprobe(p, false);
2373		}
2374	}
 
2375	mutex_unlock(&kprobe_mutex);
2376
2377	/* Wait for disarming all kprobes by optimizer */
2378	wait_for_kprobe_optimizer();
2379}
2380
2381/*
2382 * XXX: The debugfs bool file interface doesn't allow for callbacks
2383 * when the bool state is switched. We can reuse that facility when
2384 * available
2385 */
2386static ssize_t read_enabled_file_bool(struct file *file,
2387	       char __user *user_buf, size_t count, loff_t *ppos)
2388{
2389	char buf[3];
2390
2391	if (!kprobes_all_disarmed)
2392		buf[0] = '1';
2393	else
2394		buf[0] = '0';
2395	buf[1] = '\n';
2396	buf[2] = 0x00;
2397	return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2398}
2399
2400static ssize_t write_enabled_file_bool(struct file *file,
2401	       const char __user *user_buf, size_t count, loff_t *ppos)
2402{
2403	char buf[32];
2404	size_t buf_size;
2405
2406	buf_size = min(count, (sizeof(buf)-1));
2407	if (copy_from_user(buf, user_buf, buf_size))
2408		return -EFAULT;
2409
2410	buf[buf_size] = '\0';
2411	switch (buf[0]) {
2412	case 'y':
2413	case 'Y':
2414	case '1':
2415		arm_all_kprobes();
2416		break;
2417	case 'n':
2418	case 'N':
2419	case '0':
2420		disarm_all_kprobes();
2421		break;
2422	default:
2423		return -EINVAL;
2424	}
2425
2426	return count;
2427}
2428
2429static const struct file_operations fops_kp = {
2430	.read =         read_enabled_file_bool,
2431	.write =        write_enabled_file_bool,
2432	.llseek =	default_llseek,
2433};
2434
2435static int __init debugfs_kprobe_init(void)
2436{
2437	struct dentry *dir, *file;
2438	unsigned int value = 1;
2439
2440	dir = debugfs_create_dir("kprobes", NULL);
2441	if (!dir)
2442		return -ENOMEM;
2443
2444	file = debugfs_create_file("list", 0444, dir, NULL,
2445				&debugfs_kprobes_operations);
2446	if (!file)
2447		goto error;
 
 
2448
2449	file = debugfs_create_file("enabled", 0600, dir,
2450					&value, &fops_kp);
2451	if (!file)
2452		goto error;
2453
2454	file = debugfs_create_file("blacklist", 0444, dir, NULL,
2455				&debugfs_kprobe_blacklist_ops);
2456	if (!file)
2457		goto error;
2458
2459	return 0;
2460
2461error:
2462	debugfs_remove(dir);
2463	return -ENOMEM;
2464}
2465
2466late_initcall(debugfs_kprobe_init);
2467#endif /* CONFIG_DEBUG_FS */
2468
2469module_init(init_kprobes);
2470
2471/* defined in arch/.../kernel/kprobes.c */
2472EXPORT_SYMBOL_GPL(jprobe_return);