1/*
   2 * User-space Probes (UProbes)
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License as published by
   6 * the Free Software Foundation; either version 2 of the License, or
   7 * (at your option) any later version.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17 *
  18 * Copyright (C) IBM Corporation, 2008-2012
  19 * Authors:
  20 *	Srikar Dronamraju
  21 *	Jim Keniston
  22 * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra
  23 */
  24
  25#include <linux/kernel.h>
  26#include <linux/highmem.h>
  27#include <linux/pagemap.h>	/* read_mapping_page */
  28#include <linux/slab.h>
  29#include <linux/sched.h>
 
 
  30#include <linux/export.h>
  31#include <linux/rmap.h>		/* anon_vma_prepare */
  32#include <linux/mmu_notifier.h>	/* set_pte_at_notify */
  33#include <linux/swap.h>		/* try_to_free_swap */
  34#include <linux/ptrace.h>	/* user_enable_single_step */
  35#include <linux/kdebug.h>	/* notifier mechanism */
  36#include "../../mm/internal.h"	/* munlock_vma_page */
  37#include <linux/percpu-rwsem.h>
  38#include <linux/task_work.h>
  39#include <linux/shmem_fs.h>
 
  40
  41#include <linux/uprobes.h>
  42
  43#define UINSNS_PER_PAGE			(PAGE_SIZE/UPROBE_XOL_SLOT_BYTES)
  44#define MAX_UPROBE_XOL_SLOTS		UINSNS_PER_PAGE
  45
  46static struct rb_root uprobes_tree = RB_ROOT;
  47/*
  48 * allows us to skip the uprobe_mmap if there are no uprobe events active
  49 * at this time.  Probably a fine grained per inode count is better?
  50 */
  51#define no_uprobe_events()	RB_EMPTY_ROOT(&uprobes_tree)
  52
  53static DEFINE_SPINLOCK(uprobes_treelock);	/* serialize rbtree access */
  54
  55#define UPROBES_HASH_SZ	13
  56/* serialize uprobe->pending_list */
  57static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];
  58#define uprobes_mmap_hash(v)	(&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ])
  59
  60static struct percpu_rw_semaphore dup_mmap_sem;
  61
  62/* Have a copy of original instruction */
  63#define UPROBE_COPY_INSN	0
  64
  65struct uprobe {
  66	struct rb_node		rb_node;	/* node in the rb tree */
  67	atomic_t		ref;
  68	struct rw_semaphore	register_rwsem;
  69	struct rw_semaphore	consumer_rwsem;
  70	struct list_head	pending_list;
  71	struct uprobe_consumer	*consumers;
  72	struct inode		*inode;		/* Also hold a ref to inode */
  73	loff_t			offset;
 
  74	unsigned long		flags;
  75
  76	/*
  77	 * The generic code assumes that it has two members of unknown type
  78	 * owned by the arch-specific code:
  79	 *
  80	 * 	insn -	copy_insn() saves the original instruction here for
  81	 *		arch_uprobe_analyze_insn().
  82	 *
  83	 *	ixol -	potentially modified instruction to execute out of
  84	 *		line, copied to xol_area by xol_get_insn_slot().
  85	 */
  86	struct arch_uprobe	arch;
  87};
  88
 
 
 
 
 
 
 
 
 
  89/*
  90 * Execute out of line area: anonymous executable mapping installed
  91 * by the probed task to execute the copy of the original instruction
  92 * mangled by set_swbp().
  93 *
  94 * On a breakpoint hit, thread contests for a slot.  It frees the
  95 * slot after singlestep. Currently a fixed number of slots are
  96 * allocated.
  97 */
  98struct xol_area {
  99	wait_queue_head_t 		wq;		/* if all slots are busy */
 100	atomic_t 			slot_count;	/* number of in-use slots */
 101	unsigned long 			*bitmap;	/* 0 = free slot */
 102
 103	struct vm_special_mapping	xol_mapping;
 104	struct page 			*pages[2];
 105	/*
 106	 * We keep the vma's vm_start rather than a pointer to the vma
 107	 * itself.  The probed process or a naughty kernel module could make
 108	 * the vma go away, and we must handle that reasonably gracefully.
 109	 */
 110	unsigned long 			vaddr;		/* Page(s) of instruction slots */
 111};
 112
 113/*
 114 * valid_vma: Verify if the specified vma is an executable vma
 115 * Relax restrictions while unregistering: vm_flags might have
 116 * changed after breakpoint was inserted.
 117 *	- is_register: indicates if we are in register context.
 118 *	- Return 1 if the specified virtual address is in an
 119 *	  executable vma.
 120 */
 121static bool valid_vma(struct vm_area_struct *vma, bool is_register)
 122{
 123	vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE;
 124
 125	if (is_register)
 126		flags |= VM_WRITE;
 127
 128	return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC;
 129}
 130
 131static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
 132{
 133	return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 134}
 135
 136static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr)
 137{
 138	return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start);
 139}
 140
 141/**
 142 * __replace_page - replace page in vma by new page.
 143 * based on replace_page in mm/ksm.c
 144 *
 145 * @vma:      vma that holds the pte pointing to page
 146 * @addr:     address the old @page is mapped at
 147 * @page:     the cowed page we are replacing by kpage
 148 * @kpage:    the modified page we replace page by
 
 
 149 *
 150 * Returns 0 on success, -EFAULT on failure.
 151 */
 152static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 153				struct page *old_page, struct page *new_page)
 154{
 155	struct mm_struct *mm = vma->vm_mm;
 156	spinlock_t *ptl;
 157	pte_t *ptep;
 
 
 
 158	int err;
 159	/* For mmu_notifiers */
 160	const unsigned long mmun_start = addr;
 161	const unsigned long mmun_end   = addr + PAGE_SIZE;
 162	struct mem_cgroup *memcg;
 163
 164	err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg,
 165			false);
 166	if (err)
 167		return err;
 
 168
 169	/* For try_to_free_swap() and munlock_vma_page() below */
 170	lock_page(old_page);
 171
 172	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 173	err = -EAGAIN;
 174	ptep = page_check_address(old_page, mm, addr, &ptl, 0);
 175	if (!ptep) {
 176		mem_cgroup_cancel_charge(new_page, memcg, false);
 177		goto unlock;
 178	}
 179
 180	get_page(new_page);
 181	page_add_new_anon_rmap(new_page, vma, addr, false);
 182	mem_cgroup_commit_charge(new_page, memcg, false, false);
 183	lru_cache_add_active_or_unevictable(new_page, vma);
 
 
 
 184
 185	if (!PageAnon(old_page)) {
 186		dec_mm_counter(mm, mm_counter_file(old_page));
 187		inc_mm_counter(mm, MM_ANONPAGES);
 188	}
 189
 190	flush_cache_page(vma, addr, pte_pfn(*ptep));
 191	ptep_clear_flush_notify(vma, addr, ptep);
 192	set_pte_at_notify(mm, addr, ptep, mk_pte(new_page, vma->vm_page_prot));
 
 
 193
 194	page_remove_rmap(old_page, false);
 195	if (!page_mapped(old_page))
 196		try_to_free_swap(old_page);
 197	pte_unmap_unlock(ptep, ptl);
 198
 199	if (vma->vm_flags & VM_LOCKED)
 200		munlock_vma_page(old_page);
 201	put_page(old_page);
 202
 203	err = 0;
 204 unlock:
 205	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
 206	unlock_page(old_page);
 207	return err;
 208}
 209
 210/**
 211 * is_swbp_insn - check if instruction is breakpoint instruction.
 212 * @insn: instruction to be checked.
 213 * Default implementation of is_swbp_insn
 214 * Returns true if @insn is a breakpoint instruction.
 215 */
 216bool __weak is_swbp_insn(uprobe_opcode_t *insn)
 217{
 218	return *insn == UPROBE_SWBP_INSN;
 219}
 220
 221/**
 222 * is_trap_insn - check if instruction is breakpoint instruction.
 223 * @insn: instruction to be checked.
 224 * Default implementation of is_trap_insn
 225 * Returns true if @insn is a breakpoint instruction.
 226 *
 227 * This function is needed for the case where an architecture has multiple
 228 * trap instructions (like powerpc).
 229 */
 230bool __weak is_trap_insn(uprobe_opcode_t *insn)
 231{
 232	return is_swbp_insn(insn);
 233}
 234
 235static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
 236{
 237	void *kaddr = kmap_atomic(page);
 238	memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
 239	kunmap_atomic(kaddr);
 240}
 241
 242static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len)
 243{
 244	void *kaddr = kmap_atomic(page);
 245	memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
 246	kunmap_atomic(kaddr);
 247}
 248
 249static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
 250{
 251	uprobe_opcode_t old_opcode;
 252	bool is_swbp;
 253
 254	/*
 255	 * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here.
 256	 * We do not check if it is any other 'trap variant' which could
 257	 * be conditional trap instruction such as the one powerpc supports.
 258	 *
 259	 * The logic is that we do not care if the underlying instruction
 260	 * is a trap variant; uprobes always wins over any other (gdb)
 261	 * breakpoint.
 262	 */
 263	copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
 264	is_swbp = is_swbp_insn(&old_opcode);
 265
 266	if (is_swbp_insn(new_opcode)) {
 267		if (is_swbp)		/* register: already installed? */
 268			return 0;
 269	} else {
 270		if (!is_swbp)		/* unregister: was it changed by us? */
 271			return 0;
 272	}
 273
 274	return 1;
 275}
 276
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 277/*
 278 * NOTE:
 279 * Expect the breakpoint instruction to be the smallest size instruction for
 280 * the architecture. If an arch has variable length instruction and the
 281 * breakpoint instruction is not of the smallest length instruction
 282 * supported by that architecture then we need to modify is_trap_at_addr and
 283 * uprobe_write_opcode accordingly. This would never be a problem for archs
 284 * that have fixed length instructions.
 285 *
 286 * uprobe_write_opcode - write the opcode at a given virtual address.
 287 * @mm: the probed process address space.
 288 * @vaddr: the virtual address to store the opcode.
 289 * @opcode: opcode to be written at @vaddr.
 290 *
 291 * Called with mm->mmap_sem held for write.
 292 * Return 0 (success) or a negative errno.
 293 */
 294int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
 295			uprobe_opcode_t opcode)
 296{
 
 297	struct page *old_page, *new_page;
 298	struct vm_area_struct *vma;
 299	int ret;
 
 
 
 
 
 300
 301retry:
 
 
 302	/* Read the page with vaddr into memory */
 303	ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page,
 304			&vma, NULL);
 305	if (ret <= 0)
 306		return ret;
 307
 308	ret = verify_opcode(old_page, vaddr, &opcode);
 309	if (ret <= 0)
 310		goto put_old;
 311
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 312	ret = anon_vma_prepare(vma);
 313	if (ret)
 314		goto put_old;
 315
 316	ret = -ENOMEM;
 317	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
 318	if (!new_page)
 319		goto put_old;
 320
 321	__SetPageUptodate(new_page);
 322	copy_highpage(new_page, old_page);
 323	copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
 324
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 325	ret = __replace_page(vma, vaddr, old_page, new_page);
 326	put_page(new_page);
 
 327put_old:
 328	put_page(old_page);
 329
 330	if (unlikely(ret == -EAGAIN))
 331		goto retry;
 
 
 
 
 
 
 
 
 
 332	return ret;
 333}
 334
 335/**
 336 * set_swbp - store breakpoint at a given address.
 337 * @auprobe: arch specific probepoint information.
 338 * @mm: the probed process address space.
 339 * @vaddr: the virtual address to insert the opcode.
 340 *
 341 * For mm @mm, store the breakpoint instruction at @vaddr.
 342 * Return 0 (success) or a negative errno.
 343 */
 344int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
 345{
 346	return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
 347}
 348
 349/**
 350 * set_orig_insn - Restore the original instruction.
 351 * @mm: the probed process address space.
 352 * @auprobe: arch specific probepoint information.
 353 * @vaddr: the virtual address to insert the opcode.
 354 *
 355 * For mm @mm, restore the original opcode (opcode) at @vaddr.
 356 * Return 0 (success) or a negative errno.
 357 */
 358int __weak
 359set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
 360{
 361	return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn);
 
 362}
 363
 364static struct uprobe *get_uprobe(struct uprobe *uprobe)
 365{
 366	atomic_inc(&uprobe->ref);
 367	return uprobe;
 368}
 369
 370static void put_uprobe(struct uprobe *uprobe)
 371{
 372	if (atomic_dec_and_test(&uprobe->ref))
 
 
 
 
 
 
 
 
 373		kfree(uprobe);
 
 374}
 375
 376static int match_uprobe(struct uprobe *l, struct uprobe *r)
 377{
 378	if (l->inode < r->inode)
 379		return -1;
 380
 381	if (l->inode > r->inode)
 382		return 1;
 383
 384	if (l->offset < r->offset)
 385		return -1;
 386
 387	if (l->offset > r->offset)
 388		return 1;
 389
 390	return 0;
 391}
 392
 393static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset)
 394{
 395	struct uprobe u = { .inode = inode, .offset = offset };
 396	struct rb_node *n = uprobes_tree.rb_node;
 397	struct uprobe *uprobe;
 398	int match;
 399
 400	while (n) {
 401		uprobe = rb_entry(n, struct uprobe, rb_node);
 402		match = match_uprobe(&u, uprobe);
 403		if (!match)
 404			return get_uprobe(uprobe);
 405
 406		if (match < 0)
 407			n = n->rb_left;
 408		else
 409			n = n->rb_right;
 410	}
 411	return NULL;
 412}
 413
 414/*
 415 * Find a uprobe corresponding to a given inode:offset
 416 * Acquires uprobes_treelock
 417 */
 418static struct uprobe *find_uprobe(struct inode *inode, loff_t offset)
 419{
 420	struct uprobe *uprobe;
 421
 422	spin_lock(&uprobes_treelock);
 423	uprobe = __find_uprobe(inode, offset);
 424	spin_unlock(&uprobes_treelock);
 425
 426	return uprobe;
 427}
 428
 429static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
 430{
 431	struct rb_node **p = &uprobes_tree.rb_node;
 432	struct rb_node *parent = NULL;
 433	struct uprobe *u;
 434	int match;
 435
 436	while (*p) {
 437		parent = *p;
 438		u = rb_entry(parent, struct uprobe, rb_node);
 439		match = match_uprobe(uprobe, u);
 440		if (!match)
 441			return get_uprobe(u);
 442
 443		if (match < 0)
 444			p = &parent->rb_left;
 445		else
 446			p = &parent->rb_right;
 447
 448	}
 449
 450	u = NULL;
 451	rb_link_node(&uprobe->rb_node, parent, p);
 452	rb_insert_color(&uprobe->rb_node, &uprobes_tree);
 453	/* get access + creation ref */
 454	atomic_set(&uprobe->ref, 2);
 455
 456	return u;
 457}
 458
 459/*
 460 * Acquire uprobes_treelock.
 461 * Matching uprobe already exists in rbtree;
 462 *	increment (access refcount) and return the matching uprobe.
 463 *
 464 * No matching uprobe; insert the uprobe in rb_tree;
 465 *	get a double refcount (access + creation) and return NULL.
 466 */
 467static struct uprobe *insert_uprobe(struct uprobe *uprobe)
 468{
 469	struct uprobe *u;
 470
 471	spin_lock(&uprobes_treelock);
 472	u = __insert_uprobe(uprobe);
 473	spin_unlock(&uprobes_treelock);
 474
 475	return u;
 476}
 477
 478static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
 
 
 
 
 
 
 
 
 
 
 
 479{
 480	struct uprobe *uprobe, *cur_uprobe;
 481
 482	uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL);
 483	if (!uprobe)
 484		return NULL;
 485
 486	uprobe->inode = igrab(inode);
 487	uprobe->offset = offset;
 
 488	init_rwsem(&uprobe->register_rwsem);
 489	init_rwsem(&uprobe->consumer_rwsem);
 490
 491	/* add to uprobes_tree, sorted on inode:offset */
 492	cur_uprobe = insert_uprobe(uprobe);
 493	/* a uprobe exists for this inode:offset combination */
 494	if (cur_uprobe) {
 
 
 
 
 
 
 495		kfree(uprobe);
 496		uprobe = cur_uprobe;
 497		iput(inode);
 498	}
 499
 500	return uprobe;
 501}
 502
 503static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
 504{
 505	down_write(&uprobe->consumer_rwsem);
 506	uc->next = uprobe->consumers;
 507	uprobe->consumers = uc;
 508	up_write(&uprobe->consumer_rwsem);
 509}
 510
 511/*
 512 * For uprobe @uprobe, delete the consumer @uc.
 513 * Return true if the @uc is deleted successfully
 514 * or return false.
 515 */
 516static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc)
 517{
 518	struct uprobe_consumer **con;
 519	bool ret = false;
 520
 521	down_write(&uprobe->consumer_rwsem);
 522	for (con = &uprobe->consumers; *con; con = &(*con)->next) {
 523		if (*con == uc) {
 524			*con = uc->next;
 525			ret = true;
 526			break;
 527		}
 528	}
 529	up_write(&uprobe->consumer_rwsem);
 530
 531	return ret;
 532}
 533
 534static int __copy_insn(struct address_space *mapping, struct file *filp,
 535			void *insn, int nbytes, loff_t offset)
 536{
 537	struct page *page;
 538	/*
 539	 * Ensure that the page that has the original instruction is populated
 540	 * and in page-cache. If ->readpage == NULL it must be shmem_mapping(),
 541	 * see uprobe_register().
 542	 */
 543	if (mapping->a_ops->readpage)
 544		page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp);
 545	else
 546		page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT);
 547	if (IS_ERR(page))
 548		return PTR_ERR(page);
 549
 550	copy_from_page(page, offset, insn, nbytes);
 551	put_page(page);
 552
 553	return 0;
 554}
 555
 556static int copy_insn(struct uprobe *uprobe, struct file *filp)
 557{
 558	struct address_space *mapping = uprobe->inode->i_mapping;
 559	loff_t offs = uprobe->offset;
 560	void *insn = &uprobe->arch.insn;
 561	int size = sizeof(uprobe->arch.insn);
 562	int len, err = -EIO;
 563
 564	/* Copy only available bytes, -EIO if nothing was read */
 565	do {
 566		if (offs >= i_size_read(uprobe->inode))
 567			break;
 568
 569		len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK));
 570		err = __copy_insn(mapping, filp, insn, len, offs);
 571		if (err)
 572			break;
 573
 574		insn += len;
 575		offs += len;
 576		size -= len;
 577	} while (size);
 578
 579	return err;
 580}
 581
 582static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
 583				struct mm_struct *mm, unsigned long vaddr)
 584{
 585	int ret = 0;
 586
 587	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
 588		return ret;
 589
 590	/* TODO: move this into _register, until then we abuse this sem. */
 591	down_write(&uprobe->consumer_rwsem);
 592	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
 593		goto out;
 594
 595	ret = copy_insn(uprobe, file);
 596	if (ret)
 597		goto out;
 598
 599	ret = -ENOTSUPP;
 600	if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn))
 601		goto out;
 602
 603	ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr);
 604	if (ret)
 605		goto out;
 606
 607	/* uprobe_write_opcode() assumes we don't cross page boundary */
 608	BUG_ON((uprobe->offset & ~PAGE_MASK) +
 609			UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
 610
 611	smp_wmb(); /* pairs with rmb() in find_active_uprobe() */
 612	set_bit(UPROBE_COPY_INSN, &uprobe->flags);
 613
 614 out:
 615	up_write(&uprobe->consumer_rwsem);
 616
 617	return ret;
 618}
 619
 620static inline bool consumer_filter(struct uprobe_consumer *uc,
 621				   enum uprobe_filter_ctx ctx, struct mm_struct *mm)
 622{
 623	return !uc->filter || uc->filter(uc, ctx, mm);
 624}
 625
 626static bool filter_chain(struct uprobe *uprobe,
 627			 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
 628{
 629	struct uprobe_consumer *uc;
 630	bool ret = false;
 631
 632	down_read(&uprobe->consumer_rwsem);
 633	for (uc = uprobe->consumers; uc; uc = uc->next) {
 634		ret = consumer_filter(uc, ctx, mm);
 635		if (ret)
 636			break;
 637	}
 638	up_read(&uprobe->consumer_rwsem);
 639
 640	return ret;
 641}
 642
 643static int
 644install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
 645			struct vm_area_struct *vma, unsigned long vaddr)
 646{
 647	bool first_uprobe;
 648	int ret;
 649
 650	ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr);
 651	if (ret)
 652		return ret;
 653
 654	/*
 655	 * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(),
 656	 * the task can hit this breakpoint right after __replace_page().
 657	 */
 658	first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags);
 659	if (first_uprobe)
 660		set_bit(MMF_HAS_UPROBES, &mm->flags);
 661
 662	ret = set_swbp(&uprobe->arch, mm, vaddr);
 663	if (!ret)
 664		clear_bit(MMF_RECALC_UPROBES, &mm->flags);
 665	else if (first_uprobe)
 666		clear_bit(MMF_HAS_UPROBES, &mm->flags);
 667
 668	return ret;
 669}
 670
 671static int
 672remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
 673{
 674	set_bit(MMF_RECALC_UPROBES, &mm->flags);
 675	return set_orig_insn(&uprobe->arch, mm, vaddr);
 676}
 677
 678static inline bool uprobe_is_active(struct uprobe *uprobe)
 679{
 680	return !RB_EMPTY_NODE(&uprobe->rb_node);
 681}
 682/*
 683 * There could be threads that have already hit the breakpoint. They
 684 * will recheck the current insn and restart if find_uprobe() fails.
 685 * See find_active_uprobe().
 686 */
 687static void delete_uprobe(struct uprobe *uprobe)
 688{
 689	if (WARN_ON(!uprobe_is_active(uprobe)))
 690		return;
 691
 692	spin_lock(&uprobes_treelock);
 693	rb_erase(&uprobe->rb_node, &uprobes_tree);
 694	spin_unlock(&uprobes_treelock);
 695	RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */
 696	iput(uprobe->inode);
 697	put_uprobe(uprobe);
 698}
 699
 700struct map_info {
 701	struct map_info *next;
 702	struct mm_struct *mm;
 703	unsigned long vaddr;
 704};
 705
 706static inline struct map_info *free_map_info(struct map_info *info)
 707{
 708	struct map_info *next = info->next;
 709	kfree(info);
 710	return next;
 711}
 712
 713static struct map_info *
 714build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
 715{
 716	unsigned long pgoff = offset >> PAGE_SHIFT;
 717	struct vm_area_struct *vma;
 718	struct map_info *curr = NULL;
 719	struct map_info *prev = NULL;
 720	struct map_info *info;
 721	int more = 0;
 722
 723 again:
 724	i_mmap_lock_read(mapping);
 725	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
 726		if (!valid_vma(vma, is_register))
 727			continue;
 728
 729		if (!prev && !more) {
 730			/*
 731			 * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through
 732			 * reclaim. This is optimistic, no harm done if it fails.
 733			 */
 734			prev = kmalloc(sizeof(struct map_info),
 735					GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN);
 736			if (prev)
 737				prev->next = NULL;
 738		}
 739		if (!prev) {
 740			more++;
 741			continue;
 742		}
 743
 744		if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
 745			continue;
 746
 747		info = prev;
 748		prev = prev->next;
 749		info->next = curr;
 750		curr = info;
 751
 752		info->mm = vma->vm_mm;
 753		info->vaddr = offset_to_vaddr(vma, offset);
 754	}
 755	i_mmap_unlock_read(mapping);
 756
 757	if (!more)
 758		goto out;
 759
 760	prev = curr;
 761	while (curr) {
 762		mmput(curr->mm);
 763		curr = curr->next;
 764	}
 765
 766	do {
 767		info = kmalloc(sizeof(struct map_info), GFP_KERNEL);
 768		if (!info) {
 769			curr = ERR_PTR(-ENOMEM);
 770			goto out;
 771		}
 772		info->next = prev;
 773		prev = info;
 774	} while (--more);
 775
 776	goto again;
 777 out:
 778	while (prev)
 779		prev = free_map_info(prev);
 780	return curr;
 781}
 782
 783static int
 784register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new)
 785{
 786	bool is_register = !!new;
 787	struct map_info *info;
 788	int err = 0;
 789
 790	percpu_down_write(&dup_mmap_sem);
 791	info = build_map_info(uprobe->inode->i_mapping,
 792					uprobe->offset, is_register);
 793	if (IS_ERR(info)) {
 794		err = PTR_ERR(info);
 795		goto out;
 796	}
 797
 798	while (info) {
 799		struct mm_struct *mm = info->mm;
 800		struct vm_area_struct *vma;
 801
 802		if (err && is_register)
 803			goto free;
 804
 805		down_write(&mm->mmap_sem);
 806		vma = find_vma(mm, info->vaddr);
 807		if (!vma || !valid_vma(vma, is_register) ||
 808		    file_inode(vma->vm_file) != uprobe->inode)
 809			goto unlock;
 810
 811		if (vma->vm_start > info->vaddr ||
 812		    vaddr_to_offset(vma, info->vaddr) != uprobe->offset)
 813			goto unlock;
 814
 815		if (is_register) {
 816			/* consult only the "caller", new consumer. */
 817			if (consumer_filter(new,
 818					UPROBE_FILTER_REGISTER, mm))
 819				err = install_breakpoint(uprobe, mm, vma, info->vaddr);
 820		} else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) {
 821			if (!filter_chain(uprobe,
 822					UPROBE_FILTER_UNREGISTER, mm))
 823				err |= remove_breakpoint(uprobe, mm, info->vaddr);
 824		}
 825
 826 unlock:
 827		up_write(&mm->mmap_sem);
 828 free:
 829		mmput(mm);
 830		info = free_map_info(info);
 831	}
 832 out:
 833	percpu_up_write(&dup_mmap_sem);
 834	return err;
 835}
 836
 837static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
 838{
 839	consumer_add(uprobe, uc);
 840	return register_for_each_vma(uprobe, uc);
 841}
 842
 843static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
 844{
 845	int err;
 846
 847	if (WARN_ON(!consumer_del(uprobe, uc)))
 848		return;
 849
 850	err = register_for_each_vma(uprobe, NULL);
 851	/* TODO : cant unregister? schedule a worker thread */
 852	if (!uprobe->consumers && !err)
 853		delete_uprobe(uprobe);
 854}
 855
 856/*
 857 * uprobe_register - register a probe
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 858 * @inode: the file in which the probe has to be placed.
 859 * @offset: offset from the start of the file.
 860 * @uc: information on howto handle the probe..
 861 *
 862 * Apart from the access refcount, uprobe_register() takes a creation
 863 * refcount (thro alloc_uprobe) if and only if this @uprobe is getting
 864 * inserted into the rbtree (i.e first consumer for a @inode:@offset
 865 * tuple).  Creation refcount stops uprobe_unregister from freeing the
 866 * @uprobe even before the register operation is complete. Creation
 867 * refcount is released when the last @uc for the @uprobe
 868 * unregisters.
 
 869 *
 870 * Return errno if it cannot successully install probes
 871 * else return 0 (success)
 872 */
 873int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
 
 874{
 875	struct uprobe *uprobe;
 876	int ret;
 877
 878	/* Uprobe must have at least one set consumer */
 879	if (!uc->handler && !uc->ret_handler)
 880		return -EINVAL;
 881
 882	/* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */
 883	if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping))
 884		return -EIO;
 885	/* Racy, just to catch the obvious mistakes */
 886	if (offset > i_size_read(inode))
 887		return -EINVAL;
 888
 
 
 
 
 
 
 
 
 
 889 retry:
 890	uprobe = alloc_uprobe(inode, offset);
 891	if (!uprobe)
 892		return -ENOMEM;
 
 
 
 893	/*
 894	 * We can race with uprobe_unregister()->delete_uprobe().
 895	 * Check uprobe_is_active() and retry if it is false.
 896	 */
 897	down_write(&uprobe->register_rwsem);
 898	ret = -EAGAIN;
 899	if (likely(uprobe_is_active(uprobe))) {
 900		ret = __uprobe_register(uprobe, uc);
 
 901		if (ret)
 902			__uprobe_unregister(uprobe, uc);
 903	}
 904	up_write(&uprobe->register_rwsem);
 905	put_uprobe(uprobe);
 906
 907	if (unlikely(ret == -EAGAIN))
 908		goto retry;
 909	return ret;
 910}
 
 
 
 
 
 
 911EXPORT_SYMBOL_GPL(uprobe_register);
 912
 
 
 
 
 
 
 
 913/*
 914 * uprobe_apply - unregister a already registered probe.
 915 * @inode: the file in which the probe has to be removed.
 916 * @offset: offset from the start of the file.
 917 * @uc: consumer which wants to add more or remove some breakpoints
 918 * @add: add or remove the breakpoints
 919 */
 920int uprobe_apply(struct inode *inode, loff_t offset,
 921			struct uprobe_consumer *uc, bool add)
 922{
 923	struct uprobe *uprobe;
 924	struct uprobe_consumer *con;
 925	int ret = -ENOENT;
 926
 927	uprobe = find_uprobe(inode, offset);
 928	if (WARN_ON(!uprobe))
 929		return ret;
 930
 931	down_write(&uprobe->register_rwsem);
 932	for (con = uprobe->consumers; con && con != uc ; con = con->next)
 933		;
 934	if (con)
 935		ret = register_for_each_vma(uprobe, add ? uc : NULL);
 936	up_write(&uprobe->register_rwsem);
 937	put_uprobe(uprobe);
 938
 939	return ret;
 940}
 941
 942/*
 943 * uprobe_unregister - unregister a already registered probe.
 944 * @inode: the file in which the probe has to be removed.
 945 * @offset: offset from the start of the file.
 946 * @uc: identify which probe if multiple probes are colocated.
 947 */
 948void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
 949{
 950	struct uprobe *uprobe;
 951
 952	uprobe = find_uprobe(inode, offset);
 953	if (WARN_ON(!uprobe))
 954		return;
 955
 956	down_write(&uprobe->register_rwsem);
 957	__uprobe_unregister(uprobe, uc);
 958	up_write(&uprobe->register_rwsem);
 959	put_uprobe(uprobe);
 960}
 961EXPORT_SYMBOL_GPL(uprobe_unregister);
 962
 963static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
 964{
 965	struct vm_area_struct *vma;
 966	int err = 0;
 967
 968	down_read(&mm->mmap_sem);
 969	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 970		unsigned long vaddr;
 971		loff_t offset;
 972
 973		if (!valid_vma(vma, false) ||
 974		    file_inode(vma->vm_file) != uprobe->inode)
 975			continue;
 976
 977		offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
 978		if (uprobe->offset <  offset ||
 979		    uprobe->offset >= offset + vma->vm_end - vma->vm_start)
 980			continue;
 981
 982		vaddr = offset_to_vaddr(vma, uprobe->offset);
 983		err |= remove_breakpoint(uprobe, mm, vaddr);
 984	}
 985	up_read(&mm->mmap_sem);
 986
 987	return err;
 988}
 989
 990static struct rb_node *
 991find_node_in_range(struct inode *inode, loff_t min, loff_t max)
 992{
 993	struct rb_node *n = uprobes_tree.rb_node;
 994
 995	while (n) {
 996		struct uprobe *u = rb_entry(n, struct uprobe, rb_node);
 997
 998		if (inode < u->inode) {
 999			n = n->rb_left;
1000		} else if (inode > u->inode) {
1001			n = n->rb_right;
1002		} else {
1003			if (max < u->offset)
1004				n = n->rb_left;
1005			else if (min > u->offset)
1006				n = n->rb_right;
1007			else
1008				break;
1009		}
1010	}
1011
1012	return n;
1013}
1014
1015/*
1016 * For a given range in vma, build a list of probes that need to be inserted.
1017 */
1018static void build_probe_list(struct inode *inode,
1019				struct vm_area_struct *vma,
1020				unsigned long start, unsigned long end,
1021				struct list_head *head)
1022{
1023	loff_t min, max;
1024	struct rb_node *n, *t;
1025	struct uprobe *u;
1026
1027	INIT_LIST_HEAD(head);
1028	min = vaddr_to_offset(vma, start);
1029	max = min + (end - start) - 1;
1030
1031	spin_lock(&uprobes_treelock);
1032	n = find_node_in_range(inode, min, max);
1033	if (n) {
1034		for (t = n; t; t = rb_prev(t)) {
1035			u = rb_entry(t, struct uprobe, rb_node);
1036			if (u->inode != inode || u->offset < min)
1037				break;
1038			list_add(&u->pending_list, head);
1039			get_uprobe(u);
1040		}
1041		for (t = n; (t = rb_next(t)); ) {
1042			u = rb_entry(t, struct uprobe, rb_node);
1043			if (u->inode != inode || u->offset > max)
1044				break;
1045			list_add(&u->pending_list, head);
1046			get_uprobe(u);
1047		}
1048	}
1049	spin_unlock(&uprobes_treelock);
1050}
1051
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1052/*
1053 * Called from mmap_region/vma_adjust with mm->mmap_sem acquired.
1054 *
1055 * Currently we ignore all errors and always return 0, the callers
1056 * can't handle the failure anyway.
1057 */
1058int uprobe_mmap(struct vm_area_struct *vma)
1059{
1060	struct list_head tmp_list;
1061	struct uprobe *uprobe, *u;
1062	struct inode *inode;
1063
1064	if (no_uprobe_events() || !valid_vma(vma, true))
 
 
 
 
 
 
 
 
1065		return 0;
1066
1067	inode = file_inode(vma->vm_file);
1068	if (!inode)
1069		return 0;
1070
1071	mutex_lock(uprobes_mmap_hash(inode));
1072	build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);
1073	/*
1074	 * We can race with uprobe_unregister(), this uprobe can be already
1075	 * removed. But in this case filter_chain() must return false, all
1076	 * consumers have gone away.
1077	 */
1078	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
1079		if (!fatal_signal_pending(current) &&
1080		    filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) {
1081			unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
1082			install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
1083		}
1084		put_uprobe(uprobe);
1085	}
1086	mutex_unlock(uprobes_mmap_hash(inode));
1087
1088	return 0;
1089}
1090
1091static bool
1092vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end)
1093{
1094	loff_t min, max;
1095	struct inode *inode;
1096	struct rb_node *n;
1097
1098	inode = file_inode(vma->vm_file);
1099
1100	min = vaddr_to_offset(vma, start);
1101	max = min + (end - start) - 1;
1102
1103	spin_lock(&uprobes_treelock);
1104	n = find_node_in_range(inode, min, max);
1105	spin_unlock(&uprobes_treelock);
1106
1107	return !!n;
1108}
1109
1110/*
1111 * Called in context of a munmap of a vma.
1112 */
1113void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
1114{
1115	if (no_uprobe_events() || !valid_vma(vma, false))
1116		return;
1117
1118	if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
1119		return;
1120
1121	if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) ||
1122	     test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags))
1123		return;
1124
1125	if (vma_has_uprobes(vma, start, end))
1126		set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
1127}
1128
1129/* Slot allocation for XOL */
1130static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
1131{
1132	struct vm_area_struct *vma;
1133	int ret;
1134
1135	if (down_write_killable(&mm->mmap_sem))
1136		return -EINTR;
1137
1138	if (mm->uprobes_state.xol_area) {
1139		ret = -EALREADY;
1140		goto fail;
1141	}
1142
1143	if (!area->vaddr) {
1144		/* Try to map as high as possible, this is only a hint. */
1145		area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE,
1146						PAGE_SIZE, 0, 0);
1147		if (area->vaddr & ~PAGE_MASK) {
1148			ret = area->vaddr;
1149			goto fail;
1150		}
1151	}
1152
1153	vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE,
1154				VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO,
1155				&area->xol_mapping);
1156	if (IS_ERR(vma)) {
1157		ret = PTR_ERR(vma);
1158		goto fail;
1159	}
1160
1161	ret = 0;
1162	smp_wmb();	/* pairs with get_xol_area() */
1163	mm->uprobes_state.xol_area = area;
1164 fail:
1165	up_write(&mm->mmap_sem);
1166
1167	return ret;
1168}
1169
1170static struct xol_area *__create_xol_area(unsigned long vaddr)
1171{
1172	struct mm_struct *mm = current->mm;
1173	uprobe_opcode_t insn = UPROBE_SWBP_INSN;
1174	struct xol_area *area;
1175
1176	area = kmalloc(sizeof(*area), GFP_KERNEL);
1177	if (unlikely(!area))
1178		goto out;
1179
1180	area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL);
 
1181	if (!area->bitmap)
1182		goto free_area;
1183
1184	area->xol_mapping.name = "[uprobes]";
1185	area->xol_mapping.fault = NULL;
1186	area->xol_mapping.pages = area->pages;
1187	area->pages[0] = alloc_page(GFP_HIGHUSER);
1188	if (!area->pages[0])
1189		goto free_bitmap;
1190	area->pages[1] = NULL;
1191
1192	area->vaddr = vaddr;
1193	init_waitqueue_head(&area->wq);
1194	/* Reserve the 1st slot for get_trampoline_vaddr() */
1195	set_bit(0, area->bitmap);
1196	atomic_set(&area->slot_count, 1);
1197	arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE);
1198
1199	if (!xol_add_vma(mm, area))
1200		return area;
1201
1202	__free_page(area->pages[0]);
1203 free_bitmap:
1204	kfree(area->bitmap);
1205 free_area:
1206	kfree(area);
1207 out:
1208	return NULL;
1209}
1210
1211/*
1212 * get_xol_area - Allocate process's xol_area if necessary.
1213 * This area will be used for storing instructions for execution out of line.
1214 *
1215 * Returns the allocated area or NULL.
1216 */
1217static struct xol_area *get_xol_area(void)
1218{
1219	struct mm_struct *mm = current->mm;
1220	struct xol_area *area;
1221
1222	if (!mm->uprobes_state.xol_area)
1223		__create_xol_area(0);
1224
1225	area = mm->uprobes_state.xol_area;
1226	smp_read_barrier_depends();	/* pairs with wmb in xol_add_vma() */
1227	return area;
1228}
1229
1230/*
1231 * uprobe_clear_state - Free the area allocated for slots.
1232 */
1233void uprobe_clear_state(struct mm_struct *mm)
1234{
1235	struct xol_area *area = mm->uprobes_state.xol_area;
1236
 
 
 
 
1237	if (!area)
1238		return;
1239
1240	put_page(area->pages[0]);
1241	kfree(area->bitmap);
1242	kfree(area);
1243}
1244
1245void uprobe_start_dup_mmap(void)
1246{
1247	percpu_down_read(&dup_mmap_sem);
1248}
1249
1250void uprobe_end_dup_mmap(void)
1251{
1252	percpu_up_read(&dup_mmap_sem);
1253}
1254
1255void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
1256{
1257	newmm->uprobes_state.xol_area = NULL;
1258
1259	if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) {
1260		set_bit(MMF_HAS_UPROBES, &newmm->flags);
1261		/* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */
1262		set_bit(MMF_RECALC_UPROBES, &newmm->flags);
1263	}
1264}
1265
1266/*
1267 *  - search for a free slot.
1268 */
1269static unsigned long xol_take_insn_slot(struct xol_area *area)
1270{
1271	unsigned long slot_addr;
1272	int slot_nr;
1273
1274	do {
1275		slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE);
1276		if (slot_nr < UINSNS_PER_PAGE) {
1277			if (!test_and_set_bit(slot_nr, area->bitmap))
1278				break;
1279
1280			slot_nr = UINSNS_PER_PAGE;
1281			continue;
1282		}
1283		wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE));
1284	} while (slot_nr >= UINSNS_PER_PAGE);
1285
1286	slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES);
1287	atomic_inc(&area->slot_count);
1288
1289	return slot_addr;
1290}
1291
1292/*
1293 * xol_get_insn_slot - allocate a slot for xol.
1294 * Returns the allocated slot address or 0.
1295 */
1296static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
1297{
1298	struct xol_area *area;
1299	unsigned long xol_vaddr;
1300
1301	area = get_xol_area();
1302	if (!area)
1303		return 0;
1304
1305	xol_vaddr = xol_take_insn_slot(area);
1306	if (unlikely(!xol_vaddr))
1307		return 0;
1308
1309	arch_uprobe_copy_ixol(area->pages[0], xol_vaddr,
1310			      &uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
1311
1312	return xol_vaddr;
1313}
1314
1315/*
1316 * xol_free_insn_slot - If slot was earlier allocated by
1317 * @xol_get_insn_slot(), make the slot available for
1318 * subsequent requests.
1319 */
1320static void xol_free_insn_slot(struct task_struct *tsk)
1321{
1322	struct xol_area *area;
1323	unsigned long vma_end;
1324	unsigned long slot_addr;
1325
1326	if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask)
1327		return;
1328
1329	slot_addr = tsk->utask->xol_vaddr;
1330	if (unlikely(!slot_addr))
1331		return;
1332
1333	area = tsk->mm->uprobes_state.xol_area;
1334	vma_end = area->vaddr + PAGE_SIZE;
1335	if (area->vaddr <= slot_addr && slot_addr < vma_end) {
1336		unsigned long offset;
1337		int slot_nr;
1338
1339		offset = slot_addr - area->vaddr;
1340		slot_nr = offset / UPROBE_XOL_SLOT_BYTES;
1341		if (slot_nr >= UINSNS_PER_PAGE)
1342			return;
1343
1344		clear_bit(slot_nr, area->bitmap);
1345		atomic_dec(&area->slot_count);
1346		smp_mb__after_atomic(); /* pairs with prepare_to_wait() */
1347		if (waitqueue_active(&area->wq))
1348			wake_up(&area->wq);
1349
1350		tsk->utask->xol_vaddr = 0;
1351	}
1352}
1353
1354void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
1355				  void *src, unsigned long len)
1356{
1357	/* Initialize the slot */
1358	copy_to_page(page, vaddr, src, len);
1359
1360	/*
1361	 * We probably need flush_icache_user_range() but it needs vma.
1362	 * This should work on most of architectures by default. If
1363	 * architecture needs to do something different it can define
1364	 * its own version of the function.
1365	 */
1366	flush_dcache_page(page);
1367}
1368
1369/**
1370 * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
1371 * @regs: Reflects the saved state of the task after it has hit a breakpoint
1372 * instruction.
1373 * Return the address of the breakpoint instruction.
1374 */
1375unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs)
1376{
1377	return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE;
1378}
1379
1380unsigned long uprobe_get_trap_addr(struct pt_regs *regs)
1381{
1382	struct uprobe_task *utask = current->utask;
1383
1384	if (unlikely(utask && utask->active_uprobe))
1385		return utask->vaddr;
1386
1387	return instruction_pointer(regs);
1388}
1389
1390static struct return_instance *free_ret_instance(struct return_instance *ri)
1391{
1392	struct return_instance *next = ri->next;
1393	put_uprobe(ri->uprobe);
1394	kfree(ri);
1395	return next;
1396}
1397
1398/*
1399 * Called with no locks held.
1400 * Called in context of a exiting or a exec-ing thread.
1401 */
1402void uprobe_free_utask(struct task_struct *t)
1403{
1404	struct uprobe_task *utask = t->utask;
1405	struct return_instance *ri;
1406
1407	if (!utask)
1408		return;
1409
1410	if (utask->active_uprobe)
1411		put_uprobe(utask->active_uprobe);
1412
1413	ri = utask->return_instances;
1414	while (ri)
1415		ri = free_ret_instance(ri);
1416
1417	xol_free_insn_slot(t);
1418	kfree(utask);
1419	t->utask = NULL;
1420}
1421
1422/*
1423 * Allocate a uprobe_task object for the task if if necessary.
1424 * Called when the thread hits a breakpoint.
1425 *
1426 * Returns:
1427 * - pointer to new uprobe_task on success
1428 * - NULL otherwise
1429 */
1430static struct uprobe_task *get_utask(void)
1431{
1432	if (!current->utask)
1433		current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
1434	return current->utask;
1435}
1436
1437static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)
1438{
1439	struct uprobe_task *n_utask;
1440	struct return_instance **p, *o, *n;
1441
1442	n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
1443	if (!n_utask)
1444		return -ENOMEM;
1445	t->utask = n_utask;
1446
1447	p = &n_utask->return_instances;
1448	for (o = o_utask->return_instances; o; o = o->next) {
1449		n = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
1450		if (!n)
1451			return -ENOMEM;
1452
1453		*n = *o;
1454		get_uprobe(n->uprobe);
1455		n->next = NULL;
1456
1457		*p = n;
1458		p = &n->next;
1459		n_utask->depth++;
1460	}
1461
1462	return 0;
1463}
1464
1465static void uprobe_warn(struct task_struct *t, const char *msg)
1466{
1467	pr_warn("uprobe: %s:%d failed to %s\n",
1468			current->comm, current->pid, msg);
1469}
1470
1471static void dup_xol_work(struct callback_head *work)
1472{
1473	if (current->flags & PF_EXITING)
1474		return;
1475
1476	if (!__create_xol_area(current->utask->dup_xol_addr) &&
1477			!fatal_signal_pending(current))
1478		uprobe_warn(current, "dup xol area");
1479}
1480
1481/*
1482 * Called in context of a new clone/fork from copy_process.
1483 */
1484void uprobe_copy_process(struct task_struct *t, unsigned long flags)
1485{
1486	struct uprobe_task *utask = current->utask;
1487	struct mm_struct *mm = current->mm;
1488	struct xol_area *area;
1489
1490	t->utask = NULL;
1491
1492	if (!utask || !utask->return_instances)
1493		return;
1494
1495	if (mm == t->mm && !(flags & CLONE_VFORK))
1496		return;
1497
1498	if (dup_utask(t, utask))
1499		return uprobe_warn(t, "dup ret instances");
1500
1501	/* The task can fork() after dup_xol_work() fails */
1502	area = mm->uprobes_state.xol_area;
1503	if (!area)
1504		return uprobe_warn(t, "dup xol area");
1505
1506	if (mm == t->mm)
1507		return;
1508
1509	t->utask->dup_xol_addr = area->vaddr;
1510	init_task_work(&t->utask->dup_xol_work, dup_xol_work);
1511	task_work_add(t, &t->utask->dup_xol_work, true);
1512}
1513
1514/*
1515 * Current area->vaddr notion assume the trampoline address is always
1516 * equal area->vaddr.
1517 *
1518 * Returns -1 in case the xol_area is not allocated.
1519 */
1520static unsigned long get_trampoline_vaddr(void)
1521{
1522	struct xol_area *area;
1523	unsigned long trampoline_vaddr = -1;
1524
1525	area = current->mm->uprobes_state.xol_area;
1526	smp_read_barrier_depends();
1527	if (area)
1528		trampoline_vaddr = area->vaddr;
1529
1530	return trampoline_vaddr;
1531}
1532
1533static void cleanup_return_instances(struct uprobe_task *utask, bool chained,
1534					struct pt_regs *regs)
1535{
1536	struct return_instance *ri = utask->return_instances;
1537	enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL;
1538
1539	while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) {
1540		ri = free_ret_instance(ri);
1541		utask->depth--;
1542	}
1543	utask->return_instances = ri;
1544}
1545
1546static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
1547{
1548	struct return_instance *ri;
1549	struct uprobe_task *utask;
1550	unsigned long orig_ret_vaddr, trampoline_vaddr;
1551	bool chained;
1552
1553	if (!get_xol_area())
1554		return;
1555
1556	utask = get_utask();
1557	if (!utask)
1558		return;
1559
1560	if (utask->depth >= MAX_URETPROBE_DEPTH) {
1561		printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to"
1562				" nestedness limit pid/tgid=%d/%d\n",
1563				current->pid, current->tgid);
1564		return;
1565	}
1566
1567	ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
1568	if (!ri)
1569		return;
1570
1571	trampoline_vaddr = get_trampoline_vaddr();
1572	orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs);
1573	if (orig_ret_vaddr == -1)
1574		goto fail;
1575
1576	/* drop the entries invalidated by longjmp() */
1577	chained = (orig_ret_vaddr == trampoline_vaddr);
1578	cleanup_return_instances(utask, chained, regs);
1579
1580	/*
1581	 * We don't want to keep trampoline address in stack, rather keep the
1582	 * original return address of first caller thru all the consequent
1583	 * instances. This also makes breakpoint unwrapping easier.
1584	 */
1585	if (chained) {
1586		if (!utask->return_instances) {
1587			/*
1588			 * This situation is not possible. Likely we have an
1589			 * attack from user-space.
1590			 */
1591			uprobe_warn(current, "handle tail call");
1592			goto fail;
1593		}
1594		orig_ret_vaddr = utask->return_instances->orig_ret_vaddr;
1595	}
1596
1597	ri->uprobe = get_uprobe(uprobe);
1598	ri->func = instruction_pointer(regs);
1599	ri->stack = user_stack_pointer(regs);
1600	ri->orig_ret_vaddr = orig_ret_vaddr;
1601	ri->chained = chained;
1602
1603	utask->depth++;
1604	ri->next = utask->return_instances;
1605	utask->return_instances = ri;
1606
1607	return;
1608 fail:
1609	kfree(ri);
1610}
1611
1612/* Prepare to single-step probed instruction out of line. */
1613static int
1614pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
1615{
1616	struct uprobe_task *utask;
1617	unsigned long xol_vaddr;
1618	int err;
1619
1620	utask = get_utask();
1621	if (!utask)
1622		return -ENOMEM;
1623
1624	xol_vaddr = xol_get_insn_slot(uprobe);
1625	if (!xol_vaddr)
1626		return -ENOMEM;
1627
1628	utask->xol_vaddr = xol_vaddr;
1629	utask->vaddr = bp_vaddr;
1630
1631	err = arch_uprobe_pre_xol(&uprobe->arch, regs);
1632	if (unlikely(err)) {
1633		xol_free_insn_slot(current);
1634		return err;
1635	}
1636
1637	utask->active_uprobe = uprobe;
1638	utask->state = UTASK_SSTEP;
1639	return 0;
1640}
1641
1642/*
1643 * If we are singlestepping, then ensure this thread is not connected to
1644 * non-fatal signals until completion of singlestep.  When xol insn itself
1645 * triggers the signal,  restart the original insn even if the task is
1646 * already SIGKILL'ed (since coredump should report the correct ip).  This
1647 * is even more important if the task has a handler for SIGSEGV/etc, The
1648 * _same_ instruction should be repeated again after return from the signal
1649 * handler, and SSTEP can never finish in this case.
1650 */
1651bool uprobe_deny_signal(void)
1652{
1653	struct task_struct *t = current;
1654	struct uprobe_task *utask = t->utask;
1655
1656	if (likely(!utask || !utask->active_uprobe))
1657		return false;
1658
1659	WARN_ON_ONCE(utask->state != UTASK_SSTEP);
1660
1661	if (signal_pending(t)) {
1662		spin_lock_irq(&t->sighand->siglock);
1663		clear_tsk_thread_flag(t, TIF_SIGPENDING);
1664		spin_unlock_irq(&t->sighand->siglock);
1665
1666		if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) {
1667			utask->state = UTASK_SSTEP_TRAPPED;
1668			set_tsk_thread_flag(t, TIF_UPROBE);
1669		}
1670	}
1671
1672	return true;
1673}
1674
1675static void mmf_recalc_uprobes(struct mm_struct *mm)
1676{
1677	struct vm_area_struct *vma;
1678
1679	for (vma = mm->mmap; vma; vma = vma->vm_next) {
1680		if (!valid_vma(vma, false))
1681			continue;
1682		/*
1683		 * This is not strictly accurate, we can race with
1684		 * uprobe_unregister() and see the already removed
1685		 * uprobe if delete_uprobe() was not yet called.
1686		 * Or this uprobe can be filtered out.
1687		 */
1688		if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end))
1689			return;
1690	}
1691
1692	clear_bit(MMF_HAS_UPROBES, &mm->flags);
1693}
1694
1695static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
1696{
1697	struct page *page;
1698	uprobe_opcode_t opcode;
1699	int result;
1700
 
 
 
1701	pagefault_disable();
1702	result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr);
1703	pagefault_enable();
1704
1705	if (likely(result == 0))
1706		goto out;
1707
1708	/*
1709	 * The NULL 'tsk' here ensures that any faults that occur here
1710	 * will not be accounted to the task.  'mm' *is* current->mm,
1711	 * but we treat this as a 'remote' access since it is
1712	 * essentially a kernel access to the memory.
1713	 */
1714	result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page,
1715			NULL, NULL);
1716	if (result < 0)
1717		return result;
1718
1719	copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
1720	put_page(page);
1721 out:
1722	/* This needs to return true for any variant of the trap insn */
1723	return is_trap_insn(&opcode);
1724}
1725
1726static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
1727{
1728	struct mm_struct *mm = current->mm;
1729	struct uprobe *uprobe = NULL;
1730	struct vm_area_struct *vma;
1731
1732	down_read(&mm->mmap_sem);
1733	vma = find_vma(mm, bp_vaddr);
1734	if (vma && vma->vm_start <= bp_vaddr) {
1735		if (valid_vma(vma, false)) {
1736			struct inode *inode = file_inode(vma->vm_file);
1737			loff_t offset = vaddr_to_offset(vma, bp_vaddr);
1738
1739			uprobe = find_uprobe(inode, offset);
1740		}
1741
1742		if (!uprobe)
1743			*is_swbp = is_trap_at_addr(mm, bp_vaddr);
1744	} else {
1745		*is_swbp = -EFAULT;
1746	}
1747
1748	if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags))
1749		mmf_recalc_uprobes(mm);
1750	up_read(&mm->mmap_sem);
1751
1752	return uprobe;
1753}
1754
1755static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
1756{
1757	struct uprobe_consumer *uc;
1758	int remove = UPROBE_HANDLER_REMOVE;
1759	bool need_prep = false; /* prepare return uprobe, when needed */
1760
1761	down_read(&uprobe->register_rwsem);
1762	for (uc = uprobe->consumers; uc; uc = uc->next) {
1763		int rc = 0;
1764
1765		if (uc->handler) {
1766			rc = uc->handler(uc, regs);
1767			WARN(rc & ~UPROBE_HANDLER_MASK,
1768				"bad rc=0x%x from %pf()\n", rc, uc->handler);
1769		}
1770
1771		if (uc->ret_handler)
1772			need_prep = true;
1773
1774		remove &= rc;
1775	}
1776
1777	if (need_prep && !remove)
1778		prepare_uretprobe(uprobe, regs); /* put bp at return */
1779
1780	if (remove && uprobe->consumers) {
1781		WARN_ON(!uprobe_is_active(uprobe));
1782		unapply_uprobe(uprobe, current->mm);
1783	}
1784	up_read(&uprobe->register_rwsem);
1785}
1786
1787static void
1788handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs)
1789{
1790	struct uprobe *uprobe = ri->uprobe;
1791	struct uprobe_consumer *uc;
1792
1793	down_read(&uprobe->register_rwsem);
1794	for (uc = uprobe->consumers; uc; uc = uc->next) {
1795		if (uc->ret_handler)
1796			uc->ret_handler(uc, ri->func, regs);
1797	}
1798	up_read(&uprobe->register_rwsem);
1799}
1800
1801static struct return_instance *find_next_ret_chain(struct return_instance *ri)
1802{
1803	bool chained;
1804
1805	do {
1806		chained = ri->chained;
1807		ri = ri->next;	/* can't be NULL if chained */
1808	} while (chained);
1809
1810	return ri;
1811}
1812
1813static void handle_trampoline(struct pt_regs *regs)
1814{
1815	struct uprobe_task *utask;
1816	struct return_instance *ri, *next;
1817	bool valid;
1818
1819	utask = current->utask;
1820	if (!utask)
1821		goto sigill;
1822
1823	ri = utask->return_instances;
1824	if (!ri)
1825		goto sigill;
1826
1827	do {
1828		/*
1829		 * We should throw out the frames invalidated by longjmp().
1830		 * If this chain is valid, then the next one should be alive
1831		 * or NULL; the latter case means that nobody but ri->func
1832		 * could hit this trampoline on return. TODO: sigaltstack().
1833		 */
1834		next = find_next_ret_chain(ri);
1835		valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs);
1836
1837		instruction_pointer_set(regs, ri->orig_ret_vaddr);
1838		do {
1839			if (valid)
1840				handle_uretprobe_chain(ri, regs);
1841			ri = free_ret_instance(ri);
1842			utask->depth--;
1843		} while (ri != next);
1844	} while (!valid);
1845
1846	utask->return_instances = ri;
1847	return;
1848
1849 sigill:
1850	uprobe_warn(current, "handle uretprobe, sending SIGILL.");
1851	force_sig_info(SIGILL, SEND_SIG_FORCED, current);
1852
1853}
1854
1855bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs)
1856{
1857	return false;
1858}
1859
1860bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
1861					struct pt_regs *regs)
1862{
1863	return true;
1864}
1865
1866/*
1867 * Run handler and ask thread to singlestep.
1868 * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
1869 */
1870static void handle_swbp(struct pt_regs *regs)
1871{
1872	struct uprobe *uprobe;
1873	unsigned long bp_vaddr;
1874	int uninitialized_var(is_swbp);
1875
1876	bp_vaddr = uprobe_get_swbp_addr(regs);
1877	if (bp_vaddr == get_trampoline_vaddr())
1878		return handle_trampoline(regs);
1879
1880	uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
1881	if (!uprobe) {
1882		if (is_swbp > 0) {
1883			/* No matching uprobe; signal SIGTRAP. */
1884			send_sig(SIGTRAP, current, 0);
1885		} else {
1886			/*
1887			 * Either we raced with uprobe_unregister() or we can't
1888			 * access this memory. The latter is only possible if
1889			 * another thread plays with our ->mm. In both cases
1890			 * we can simply restart. If this vma was unmapped we
1891			 * can pretend this insn was not executed yet and get
1892			 * the (correct) SIGSEGV after restart.
1893			 */
1894			instruction_pointer_set(regs, bp_vaddr);
1895		}
1896		return;
1897	}
1898
1899	/* change it in advance for ->handler() and restart */
1900	instruction_pointer_set(regs, bp_vaddr);
1901
1902	/*
1903	 * TODO: move copy_insn/etc into _register and remove this hack.
1904	 * After we hit the bp, _unregister + _register can install the
1905	 * new and not-yet-analyzed uprobe at the same address, restart.
1906	 */
1907	smp_rmb(); /* pairs with wmb() in install_breakpoint() */
1908	if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
1909		goto out;
1910
 
 
 
 
 
 
 
 
 
1911	/* Tracing handlers use ->utask to communicate with fetch methods */
1912	if (!get_utask())
1913		goto out;
1914
1915	if (arch_uprobe_ignore(&uprobe->arch, regs))
1916		goto out;
1917
1918	handler_chain(uprobe, regs);
1919
1920	if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
1921		goto out;
1922
1923	if (!pre_ssout(uprobe, regs, bp_vaddr))
1924		return;
1925
1926	/* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */
1927out:
1928	put_uprobe(uprobe);
1929}
1930
1931/*
1932 * Perform required fix-ups and disable singlestep.
1933 * Allow pending signals to take effect.
1934 */
1935static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
1936{
1937	struct uprobe *uprobe;
1938	int err = 0;
1939
1940	uprobe = utask->active_uprobe;
1941	if (utask->state == UTASK_SSTEP_ACK)
1942		err = arch_uprobe_post_xol(&uprobe->arch, regs);
1943	else if (utask->state == UTASK_SSTEP_TRAPPED)
1944		arch_uprobe_abort_xol(&uprobe->arch, regs);
1945	else
1946		WARN_ON_ONCE(1);
1947
1948	put_uprobe(uprobe);
1949	utask->active_uprobe = NULL;
1950	utask->state = UTASK_RUNNING;
1951	xol_free_insn_slot(current);
1952
1953	spin_lock_irq(&current->sighand->siglock);
1954	recalc_sigpending(); /* see uprobe_deny_signal() */
1955	spin_unlock_irq(&current->sighand->siglock);
1956
1957	if (unlikely(err)) {
1958		uprobe_warn(current, "execute the probed insn, sending SIGILL.");
1959		force_sig_info(SIGILL, SEND_SIG_FORCED, current);
1960	}
1961}
1962
1963/*
1964 * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and
1965 * allows the thread to return from interrupt. After that handle_swbp()
1966 * sets utask->active_uprobe.
1967 *
1968 * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag
1969 * and allows the thread to return from interrupt.
1970 *
1971 * While returning to userspace, thread notices the TIF_UPROBE flag and calls
1972 * uprobe_notify_resume().
1973 */
1974void uprobe_notify_resume(struct pt_regs *regs)
1975{
1976	struct uprobe_task *utask;
1977
1978	clear_thread_flag(TIF_UPROBE);
1979
1980	utask = current->utask;
1981	if (utask && utask->active_uprobe)
1982		handle_singlestep(utask, regs);
1983	else
1984		handle_swbp(regs);
1985}
1986
1987/*
1988 * uprobe_pre_sstep_notifier gets called from interrupt context as part of
1989 * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit.
1990 */
1991int uprobe_pre_sstep_notifier(struct pt_regs *regs)
1992{
1993	if (!current->mm)
1994		return 0;
1995
1996	if (!test_bit(MMF_HAS_UPROBES, &current->mm->flags) &&
1997	    (!current->utask || !current->utask->return_instances))
1998		return 0;
1999
2000	set_thread_flag(TIF_UPROBE);
2001	return 1;
2002}
2003
2004/*
2005 * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier
2006 * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep.
2007 */
2008int uprobe_post_sstep_notifier(struct pt_regs *regs)
2009{
2010	struct uprobe_task *utask = current->utask;
2011
2012	if (!current->mm || !utask || !utask->active_uprobe)
2013		/* task is currently not uprobed */
2014		return 0;
2015
2016	utask->state = UTASK_SSTEP_ACK;
2017	set_thread_flag(TIF_UPROBE);
2018	return 1;
2019}
2020
2021static struct notifier_block uprobe_exception_nb = {
2022	.notifier_call		= arch_uprobe_exception_notify,
2023	.priority		= INT_MAX-1,	/* notified after kprobes, kgdb */
2024};
2025
2026static int __init init_uprobes(void)
2027{
2028	int i;
2029
2030	for (i = 0; i < UPROBES_HASH_SZ; i++)
2031		mutex_init(&uprobes_mmap_mutex[i]);
2032
2033	if (percpu_init_rwsem(&dup_mmap_sem))
2034		return -ENOMEM;
2035
2036	return register_die_notifier(&uprobe_exception_nb);
2037}
2038__initcall(init_uprobes);