mmap.c 71.3 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5
/*
 * mm/mmap.c
 *
 * Written by obz.
 *
Alan Cox's avatar
Alan Cox committed
6
 * Address space accounting code	<alan@lxorguk.ukuu.org.uk>
Linus Torvalds's avatar
Linus Torvalds committed
7 8 9
 */

#include <linux/slab.h>
Alexey Dobriyan's avatar
Alexey Dobriyan committed
10
#include <linux/backing-dev.h>
Linus Torvalds's avatar
Linus Torvalds committed
11 12 13 14 15 16
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
17
#include <linux/capability.h>
Linus Torvalds's avatar
Linus Torvalds committed
18 19 20 21 22 23 24
#include <linux/init.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/hugetlb.h>
#include <linux/profile.h>
25
#include <linux/export.h>
Linus Torvalds's avatar
Linus Torvalds committed
26 27 28
#include <linux/mount.h>
#include <linux/mempolicy.h>
#include <linux/rmap.h>
Andrea Arcangeli's avatar
Andrea Arcangeli committed
29
#include <linux/mmu_notifier.h>
30
#include <linux/perf_event.h>
Al Viro's avatar
Al Viro committed
31
#include <linux/audit.h>
Andrea Arcangeli's avatar
Andrea Arcangeli committed
32
#include <linux/khugepaged.h>
33
#include <linux/uprobes.h>
Linus Torvalds's avatar
Linus Torvalds committed
34 35 36 37

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/tlb.h>
38
#include <asm/mmu_context.h>
Linus Torvalds's avatar
Linus Torvalds committed
39

40 41
#include "internal.h"

42 43 44 45
#ifndef arch_mmap_check
#define arch_mmap_check(addr, len, flags)	(0)
#endif

46 47 48 49
#ifndef arch_rebalance_pgtables
#define arch_rebalance_pgtables(addr, len)		(addr)
#endif

50 51 52 53
static void unmap_region(struct mm_struct *mm,
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end);

Linus Torvalds's avatar
Linus Torvalds committed
54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73
/* description of effects of mapping type and prot in current implementation.
 * this is due to the limited x86 page protection hardware.  The expected
 * behavior is in parens:
 *
 * map_type	prot
 *		PROT_NONE	PROT_READ	PROT_WRITE	PROT_EXEC
 * MAP_SHARED	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
 *		w: (no) no	w: (no) no	w: (yes) yes	w: (no) no
 *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
 *		
 * MAP_PRIVATE	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
 *		w: (no) no	w: (no) no	w: (copy) copy	w: (no) no
 *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
 *
 */
pgprot_t protection_map[16] = {
	__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
	__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
};

74 75
pgprot_t vm_get_page_prot(unsigned long vm_flags)
{
76 77 78
	return __pgprot(pgprot_val(protection_map[vm_flags &
				(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
			pgprot_val(arch_vm_get_page_prot(vm_flags)));
79 80 81
}
EXPORT_SYMBOL(vm_get_page_prot);

82 83
int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
int sysctl_overcommit_ratio __read_mostly = 50;	/* default is 50% */
84
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
85 86 87 88 89
/*
 * Make sure vm_committed_as in one cacheline and not cacheline shared with
 * other variables. It can be updated by several CPUs frequently.
 */
struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
Linus Torvalds's avatar
Linus Torvalds committed
90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106

/*
 * Check that a process has enough memory to allocate a new virtual
 * mapping. 0 means there is enough memory for the allocation to
 * succeed and -ENOMEM implies there is not.
 *
 * We currently support three overcommit policies, which are set via the
 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
 *
 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 * Additional code 2002 Jul 20 by Robert Love.
 *
 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 *
 * Note this is a helper function intended to be used by LSMs which
 * wish to use this logic.
 */
107
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
Linus Torvalds's avatar
Linus Torvalds committed
108 109 110 111 112 113 114 115 116 117 118 119
{
	unsigned long free, allowed;

	vm_acct_memory(pages);

	/*
	 * Sometimes we want to use more memory than we have
	 */
	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
		return 0;

	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
120 121 122 123 124 125 126 127 128 129
		free = global_page_state(NR_FREE_PAGES);
		free += global_page_state(NR_FILE_PAGES);

		/*
		 * shmem pages shouldn't be counted as free in this
		 * case, they can't be purged, only swapped out, and
		 * that won't affect the overall amount of available
		 * memory in the system.
		 */
		free -= global_page_state(NR_SHMEM);
Linus Torvalds's avatar
Linus Torvalds committed
130 131 132 133 134 135 136 137 138

		free += nr_swap_pages;

		/*
		 * Any slabs which are created with the
		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
		 * which are reclaimable, under pressure.  The dentry
		 * cache and most inode caches should fall into this
		 */
139
		free += global_page_state(NR_SLAB_RECLAIMABLE);
Linus Torvalds's avatar
Linus Torvalds committed
140

141 142 143
		/*
		 * Leave reserved pages. The pages are not for anonymous pages.
		 */
144
		if (free <= totalreserve_pages)
145 146
			goto error;
		else
147
			free -= totalreserve_pages;
148 149 150 151

		/*
		 * Leave the last 3% for root
		 */
Linus Torvalds's avatar
Linus Torvalds committed
152
		if (!cap_sys_admin)
153
			free -= free / 32;
Linus Torvalds's avatar
Linus Torvalds committed
154 155 156

		if (free > pages)
			return 0;
157 158

		goto error;
Linus Torvalds's avatar
Linus Torvalds committed
159 160 161 162 163 164 165 166 167 168 169 170 171
	}

	allowed = (totalram_pages - hugetlb_total_pages())
	       	* sysctl_overcommit_ratio / 100;
	/*
	 * Leave the last 3% for root
	 */
	if (!cap_sys_admin)
		allowed -= allowed / 32;
	allowed += total_swap_pages;

	/* Don't let a single process grow too big:
	   leave 3% of the size of this process for other processes */
Alan Cox's avatar
Alan Cox committed
172 173
	if (mm)
		allowed -= mm->total_vm / 32;
Linus Torvalds's avatar
Linus Torvalds committed
174

175
	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
Linus Torvalds's avatar
Linus Torvalds committed
176
		return 0;
177
error:
Linus Torvalds's avatar
Linus Torvalds committed
178 179 180 181 182 183
	vm_unacct_memory(pages);

	return -ENOMEM;
}

/*
184
 * Requires inode->i_mapping->i_mmap_mutex
Linus Torvalds's avatar
Linus Torvalds committed
185 186 187 188 189
 */
static void __remove_shared_vm_struct(struct vm_area_struct *vma,
		struct file *file, struct address_space *mapping)
{
	if (vma->vm_flags & VM_DENYWRITE)
190
		atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds's avatar
Linus Torvalds committed
191 192 193 194 195
	if (vma->vm_flags & VM_SHARED)
		mapping->i_mmap_writable--;

	flush_dcache_mmap_lock(mapping);
	if (unlikely(vma->vm_flags & VM_NONLINEAR))
196
		list_del_init(&vma->shared.nonlinear);
Linus Torvalds's avatar
Linus Torvalds committed
197
	else
198
		vma_interval_tree_remove(vma, &mapping->i_mmap);
Linus Torvalds's avatar
Linus Torvalds committed
199 200 201 202
	flush_dcache_mmap_unlock(mapping);
}

/*
203
 * Unlink a file-based vm structure from its interval tree, to hide
204
 * vma from rmap and vmtruncate before freeing its page tables.
Linus Torvalds's avatar
Linus Torvalds committed
205
 */
206
void unlink_file_vma(struct vm_area_struct *vma)
Linus Torvalds's avatar
Linus Torvalds committed
207 208 209 210 211
{
	struct file *file = vma->vm_file;

	if (file) {
		struct address_space *mapping = file->f_mapping;
212
		mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
213
		__remove_shared_vm_struct(vma, file, mapping);
214
		mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
215
	}
216 217 218 219 220 221 222 223 224 225
}

/*
 * Close a vm structure and free it, returning the next.
 */
static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
{
	struct vm_area_struct *next = vma->vm_next;

	might_sleep();
Linus Torvalds's avatar
Linus Torvalds committed
226 227
	if (vma->vm_ops && vma->vm_ops->close)
		vma->vm_ops->close(vma);
228
	if (vma->vm_file)
229
		fput(vma->vm_file);
230
	mpol_put(vma_policy(vma));
Linus Torvalds's avatar
Linus Torvalds committed
231
	kmem_cache_free(vm_area_cachep, vma);
232
	return next;
Linus Torvalds's avatar
Linus Torvalds committed
233 234
}

235 236
static unsigned long do_brk(unsigned long addr, unsigned long len);

237
SYSCALL_DEFINE1(brk, unsigned long, brk)
Linus Torvalds's avatar
Linus Torvalds committed
238 239 240 241
{
	unsigned long rlim, retval;
	unsigned long newbrk, oldbrk;
	struct mm_struct *mm = current->mm;
242
	unsigned long min_brk;
Linus Torvalds's avatar
Linus Torvalds committed
243 244 245

	down_write(&mm->mmap_sem);

246
#ifdef CONFIG_COMPAT_BRK
247 248 249 250 251
	/*
	 * CONFIG_COMPAT_BRK can still be overridden by setting
	 * randomize_va_space to 2, which will still cause mm->start_brk
	 * to be arbitrarily shifted
	 */
252
	if (current->brk_randomized)
253 254 255
		min_brk = mm->start_brk;
	else
		min_brk = mm->end_data;
256 257 258 259
#else
	min_brk = mm->start_brk;
#endif
	if (brk < min_brk)
Linus Torvalds's avatar
Linus Torvalds committed
260
		goto out;
Ram Gupta's avatar
Ram Gupta committed
261 262 263 264 265 266 267

	/*
	 * Check against rlimit here. If this check is done later after the test
	 * of oldbrk with newbrk then it can escape the test and let the data
	 * segment grow beyond its set limit the in case where the limit is
	 * not page aligned -Ram Gupta
	 */
Jiri Slaby's avatar
Jiri Slaby committed
268
	rlim = rlimit(RLIMIT_DATA);
Jiri Kosina's avatar
Jiri Kosina committed
269 270
	if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
			(mm->end_data - mm->start_data) > rlim)
Ram Gupta's avatar
Ram Gupta committed
271 272
		goto out;

Linus Torvalds's avatar
Linus Torvalds committed
273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299
	newbrk = PAGE_ALIGN(brk);
	oldbrk = PAGE_ALIGN(mm->brk);
	if (oldbrk == newbrk)
		goto set_brk;

	/* Always allow shrinking brk. */
	if (brk <= mm->brk) {
		if (!do_munmap(mm, newbrk, oldbrk-newbrk))
			goto set_brk;
		goto out;
	}

	/* Check against existing mmap mappings. */
	if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
		goto out;

	/* Ok, looks good - let it rip. */
	if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
		goto out;
set_brk:
	mm->brk = brk;
out:
	retval = mm->brk;
	up_write(&mm->mmap_sem);
	return retval;
}

300
#ifdef CONFIG_DEBUG_VM_RB
Linus Torvalds's avatar
Linus Torvalds committed
301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317
static int browse_rb(struct rb_root *root)
{
	int i = 0, j;
	struct rb_node *nd, *pn = NULL;
	unsigned long prev = 0, pend = 0;

	for (nd = rb_first(root); nd; nd = rb_next(nd)) {
		struct vm_area_struct *vma;
		vma = rb_entry(nd, struct vm_area_struct, vm_rb);
		if (vma->vm_start < prev)
			printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
		if (vma->vm_start < pend)
			printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
		if (vma->vm_start > vma->vm_end)
			printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
		i++;
		pn = nd;
David Miller's avatar
David Miller committed
318 319
		prev = vma->vm_start;
		pend = vma->vm_end;
Linus Torvalds's avatar
Linus Torvalds committed
320 321 322 323 324 325 326 327 328 329 330 331 332 333
	}
	j = 0;
	for (nd = pn; nd; nd = rb_prev(nd)) {
		j++;
	}
	if (i != j)
		printk("backwards %d, forwards %d\n", j, i), i = 0;
	return i;
}

void validate_mm(struct mm_struct *mm)
{
	int bug = 0;
	int i = 0;
334 335 336 337 338 339
	struct vm_area_struct *vma = mm->mmap;
	while (vma) {
		struct anon_vma_chain *avc;
		list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
			anon_vma_interval_tree_verify(avc);
		vma = vma->vm_next;
Linus Torvalds's avatar
Linus Torvalds committed
340 341 342 343 344 345 346
		i++;
	}
	if (i != mm->map_count)
		printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
	i = browse_rb(&mm->mm_rb);
	if (i != mm->map_count)
		printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
347
	BUG_ON(bug);
Linus Torvalds's avatar
Linus Torvalds committed
348 349 350 351 352
}
#else
#define validate_mm(mm) do { } while (0)
#endif

353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384
/*
 * vma has some anon_vma assigned, and is already inserted on that
 * anon_vma's interval trees.
 *
 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
 * vma must be removed from the anon_vma's interval trees using
 * anon_vma_interval_tree_pre_update_vma().
 *
 * After the update, the vma will be reinserted using
 * anon_vma_interval_tree_post_update_vma().
 *
 * The entire update must be protected by exclusive mmap_sem and by
 * the root anon_vma's mutex.
 */
static inline void
anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
{
	struct anon_vma_chain *avc;

	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
		anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
}

static inline void
anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
{
	struct anon_vma_chain *avc;

	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
		anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
}

385 386 387
static int find_vma_links(struct mm_struct *mm, unsigned long addr,
		unsigned long end, struct vm_area_struct **pprev,
		struct rb_node ***rb_link, struct rb_node **rb_parent)
Linus Torvalds's avatar
Linus Torvalds committed
388
{
389
	struct rb_node **__rb_link, *__rb_parent, *rb_prev;
Linus Torvalds's avatar
Linus Torvalds committed
390 391 392 393 394 395 396 397 398 399 400

	__rb_link = &mm->mm_rb.rb_node;
	rb_prev = __rb_parent = NULL;

	while (*__rb_link) {
		struct vm_area_struct *vma_tmp;

		__rb_parent = *__rb_link;
		vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);

		if (vma_tmp->vm_end > addr) {
401 402 403
			/* Fail if an existing vma overlaps the area */
			if (vma_tmp->vm_start < end)
				return -ENOMEM;
Linus Torvalds's avatar
Linus Torvalds committed
404 405 406 407 408 409 410 411 412 413 414 415
			__rb_link = &__rb_parent->rb_left;
		} else {
			rb_prev = __rb_parent;
			__rb_link = &__rb_parent->rb_right;
		}
	}

	*pprev = NULL;
	if (rb_prev)
		*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
	*rb_link = __rb_link;
	*rb_parent = __rb_parent;
416
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
417 418 419 420 421 422 423 424 425
}

void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
		struct rb_node **rb_link, struct rb_node *rb_parent)
{
	rb_link_node(&vma->vm_rb, rb_parent, rb_link);
	rb_insert_color(&vma->vm_rb, &mm->mm_rb);
}

426
static void __vma_link_file(struct vm_area_struct *vma)
Linus Torvalds's avatar
Linus Torvalds committed
427
{
ZhenwenXu's avatar
ZhenwenXu committed
428
	struct file *file;
Linus Torvalds's avatar
Linus Torvalds committed
429 430 431 432 433 434

	file = vma->vm_file;
	if (file) {
		struct address_space *mapping = file->f_mapping;

		if (vma->vm_flags & VM_DENYWRITE)
435
			atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds's avatar
Linus Torvalds committed
436 437 438 439 440 441 442
		if (vma->vm_flags & VM_SHARED)
			mapping->i_mmap_writable++;

		flush_dcache_mmap_lock(mapping);
		if (unlikely(vma->vm_flags & VM_NONLINEAR))
			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
		else
443
			vma_interval_tree_insert(vma, &mapping->i_mmap);
Linus Torvalds's avatar
Linus Torvalds committed
444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465
		flush_dcache_mmap_unlock(mapping);
	}
}

static void
__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
	struct vm_area_struct *prev, struct rb_node **rb_link,
	struct rb_node *rb_parent)
{
	__vma_link_list(mm, vma, prev, rb_parent);
	__vma_link_rb(mm, vma, rb_link, rb_parent);
}

static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
			struct vm_area_struct *prev, struct rb_node **rb_link,
			struct rb_node *rb_parent)
{
	struct address_space *mapping = NULL;

	if (vma->vm_file)
		mapping = vma->vm_file->f_mapping;

466
	if (mapping)
467
		mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
468 469 470 471 472

	__vma_link(mm, vma, prev, rb_link, rb_parent);
	__vma_link_file(vma);

	if (mapping)
473
		mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
474 475 476 477 478 479

	mm->map_count++;
	validate_mm(mm);
}

/*
480
 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
481
 * mm's list and rbtree.  It has already been inserted into the interval tree.
Linus Torvalds's avatar
Linus Torvalds committed
482
 */
ZhenwenXu's avatar
ZhenwenXu committed
483
static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
Linus Torvalds's avatar
Linus Torvalds committed
484
{
485
	struct vm_area_struct *prev;
ZhenwenXu's avatar
ZhenwenXu committed
486
	struct rb_node **rb_link, *rb_parent;
Linus Torvalds's avatar
Linus Torvalds committed
487

488 489 490
	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
			   &prev, &rb_link, &rb_parent))
		BUG();
Linus Torvalds's avatar
Linus Torvalds committed
491 492 493 494 495 496 497 498
	__vma_link(mm, vma, prev, rb_link, rb_parent);
	mm->map_count++;
}

static inline void
__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
		struct vm_area_struct *prev)
{
499 500 501 502 503
	struct vm_area_struct *next = vma->vm_next;

	prev->vm_next = next;
	if (next)
		next->vm_prev = prev;
Linus Torvalds's avatar
Linus Torvalds committed
504 505 506 507 508 509 510 511 512 513 514 515
	rb_erase(&vma->vm_rb, &mm->mm_rb);
	if (mm->mmap_cache == vma)
		mm->mmap_cache = prev;
}

/*
 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 * is already present in an i_mmap tree without adjusting the tree.
 * The following helper function should be used when such adjustments
 * are necessary.  The "insert" vma (if any) is to be inserted
 * before we drop the necessary locks.
 */
516
int vma_adjust(struct vm_area_struct *vma, unsigned long start,
Linus Torvalds's avatar
Linus Torvalds committed
517 518 519 520 521 522
	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
{
	struct mm_struct *mm = vma->vm_mm;
	struct vm_area_struct *next = vma->vm_next;
	struct vm_area_struct *importer = NULL;
	struct address_space *mapping = NULL;
523
	struct rb_root *root = NULL;
524
	struct anon_vma *anon_vma = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
525 526 527 528 529
	struct file *file = vma->vm_file;
	long adjust_next = 0;
	int remove_next = 0;

	if (next && !insert) {
530 531
		struct vm_area_struct *exporter = NULL;

Linus Torvalds's avatar
Linus Torvalds committed
532 533 534 535 536 537 538
		if (end >= next->vm_end) {
			/*
			 * vma expands, overlapping all the next, and
			 * perhaps the one after too (mprotect case 6).
			 */
again:			remove_next = 1 + (end > next->vm_end);
			end = next->vm_end;
539
			exporter = next;
Linus Torvalds's avatar
Linus Torvalds committed
540 541 542 543 544 545 546
			importer = vma;
		} else if (end > next->vm_start) {
			/*
			 * vma expands, overlapping part of the next:
			 * mprotect case 5 shifting the boundary up.
			 */
			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
547
			exporter = next;
Linus Torvalds's avatar
Linus Torvalds committed
548 549 550 551 552 553 554 555
			importer = vma;
		} else if (end < vma->vm_end) {
			/*
			 * vma shrinks, and !insert tells it's not
			 * split_vma inserting another: so it must be
			 * mprotect case 4 shifting the boundary down.
			 */
			adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
556
			exporter = vma;
Linus Torvalds's avatar
Linus Torvalds committed
557 558 559
			importer = next;
		}

560 561 562 563 564
		/*
		 * Easily overlooked: when mprotect shifts the boundary,
		 * make sure the expanding vma has anon_vma set if the
		 * shrinking vma had, to cover any anon pages imported.
		 */
565 566
		if (exporter && exporter->anon_vma && !importer->anon_vma) {
			if (anon_vma_clone(importer, exporter))
567
				return -ENOMEM;
568
			importer->anon_vma = exporter->anon_vma;
569 570 571
		}
	}

Linus Torvalds's avatar
Linus Torvalds committed
572 573
	if (file) {
		mapping = file->f_mapping;
574
		if (!(vma->vm_flags & VM_NONLINEAR)) {
Linus Torvalds's avatar
Linus Torvalds committed
575
			root = &mapping->i_mmap;
576
			uprobe_munmap(vma, vma->vm_start, vma->vm_end);
577 578

			if (adjust_next)
579 580
				uprobe_munmap(next, next->vm_start,
							next->vm_end);
581 582
		}

583
		mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
584 585
		if (insert) {
			/*
586
			 * Put into interval tree now, so instantiated pages
Linus Torvalds's avatar
Linus Torvalds committed
587 588 589 590 591 592 593 594
			 * are visible to arm/parisc __flush_dcache_page
			 * throughout; but we cannot insert into address
			 * space until vma start or end is updated.
			 */
			__vma_link_file(insert);
		}
	}

595 596
	vma_adjust_trans_huge(vma, start, end, adjust_next);

597 598 599 600
	anon_vma = vma->anon_vma;
	if (!anon_vma && adjust_next)
		anon_vma = next->anon_vma;
	if (anon_vma) {
601 602
		VM_BUG_ON(adjust_next && next->anon_vma &&
			  anon_vma != next->anon_vma);
603
		anon_vma_lock(anon_vma);
604 605 606 607
		anon_vma_interval_tree_pre_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_pre_update_vma(next);
	}
608

Linus Torvalds's avatar
Linus Torvalds committed
609 610
	if (root) {
		flush_dcache_mmap_lock(mapping);
611
		vma_interval_tree_remove(vma, root);
Linus Torvalds's avatar
Linus Torvalds committed
612
		if (adjust_next)
613
			vma_interval_tree_remove(next, root);
Linus Torvalds's avatar
Linus Torvalds committed
614 615 616 617 618 619 620 621 622 623 624 625
	}

	vma->vm_start = start;
	vma->vm_end = end;
	vma->vm_pgoff = pgoff;
	if (adjust_next) {
		next->vm_start += adjust_next << PAGE_SHIFT;
		next->vm_pgoff += adjust_next;
	}

	if (root) {
		if (adjust_next)
626 627
			vma_interval_tree_insert(next, root);
		vma_interval_tree_insert(vma, root);
Linus Torvalds's avatar
Linus Torvalds committed
628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647
		flush_dcache_mmap_unlock(mapping);
	}

	if (remove_next) {
		/*
		 * vma_merge has merged next into vma, and needs
		 * us to remove next before dropping the locks.
		 */
		__vma_unlink(mm, next, vma);
		if (file)
			__remove_shared_vm_struct(next, file, mapping);
	} else if (insert) {
		/*
		 * split_vma has split insert from vma, and needs
		 * us to insert it before dropping the locks
		 * (it may either follow vma or precede it).
		 */
		__insert_vm_struct(mm, insert);
	}

648 649 650 651
	if (anon_vma) {
		anon_vma_interval_tree_post_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_post_update_vma(next);
652
		anon_vma_unlock(anon_vma);
653
	}
Linus Torvalds's avatar
Linus Torvalds committed
654
	if (mapping)
655
		mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
656

657
	if (root) {
658
		uprobe_mmap(vma);
659 660

		if (adjust_next)
661
			uprobe_mmap(next);
662 663
	}

Linus Torvalds's avatar
Linus Torvalds committed
664
	if (remove_next) {
Matt Helsley's avatar
Matt Helsley committed
665
		if (file) {
666
			uprobe_munmap(next, next->vm_start, next->vm_end);
Linus Torvalds's avatar
Linus Torvalds committed
667
			fput(file);
Matt Helsley's avatar
Matt Helsley committed
668
		}
669 670
		if (next->anon_vma)
			anon_vma_merge(vma, next);
Linus Torvalds's avatar
Linus Torvalds committed
671
		mm->map_count--;
672
		mpol_put(vma_policy(next));
Linus Torvalds's avatar
Linus Torvalds committed
673 674 675 676 677 678 679 680 681 682 683
		kmem_cache_free(vm_area_cachep, next);
		/*
		 * In mprotect's case 6 (see comments on vma_merge),
		 * we must remove another next too. It would clutter
		 * up the code too much to do both in one go.
		 */
		if (remove_next == 2) {
			next = vma->vm_next;
			goto again;
		}
	}
684
	if (insert && file)
685
		uprobe_mmap(insert);
Linus Torvalds's avatar
Linus Torvalds committed
686 687

	validate_mm(mm);
688 689

	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
690 691 692 693 694 695 696 697 698
}

/*
 * If the vma has a ->close operation then the driver probably needs to release
 * per-vma resources, so we don't attempt to merge those.
 */
static inline int is_mergeable_vma(struct vm_area_struct *vma,
			struct file *file, unsigned long vm_flags)
{
699
	if (vma->vm_flags ^ vm_flags)
Linus Torvalds's avatar
Linus Torvalds committed
700 701 702 703 704 705 706 707 708
		return 0;
	if (vma->vm_file != file)
		return 0;
	if (vma->vm_ops && vma->vm_ops->close)
		return 0;
	return 1;
}

static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
Shaohua Li's avatar
Shaohua Li committed
709 710
					struct anon_vma *anon_vma2,
					struct vm_area_struct *vma)
Linus Torvalds's avatar
Linus Torvalds committed
711
{
Shaohua Li's avatar
Shaohua Li committed
712 713 714 715 716 717 718 719
	/*
	 * The list_is_singular() test is to avoid merging VMA cloned from
	 * parents. This can improve scalability caused by anon_vma lock.
	 */
	if ((!anon_vma1 || !anon_vma2) && (!vma ||
		list_is_singular(&vma->anon_vma_chain)))
		return 1;
	return anon_vma1 == anon_vma2;
Linus Torvalds's avatar
Linus Torvalds committed
720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737
}

/*
 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 * in front of (at a lower virtual address and file offset than) the vma.
 *
 * We cannot merge two vmas if they have differently assigned (non-NULL)
 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 *
 * We don't check here for the merged mmap wrapping around the end of pagecache
 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 * wrap, nor mmaps which cover the final page at index -1UL.
 */
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
	if (is_mergeable_vma(vma, file, vm_flags) &&
Shaohua Li's avatar
Shaohua Li committed
738
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
Linus Torvalds's avatar
Linus Torvalds committed
739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756
		if (vma->vm_pgoff == vm_pgoff)
			return 1;
	}
	return 0;
}

/*
 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 * beyond (at a higher virtual address and file offset than) the vma.
 *
 * We cannot merge two vmas if they have differently assigned (non-NULL)
 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 */
static int
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
	if (is_mergeable_vma(vma, file, vm_flags) &&
Shaohua Li's avatar
Shaohua Li committed
757
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
Linus Torvalds's avatar
Linus Torvalds committed
758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802
		pgoff_t vm_pglen;
		vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
			return 1;
	}
	return 0;
}

/*
 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
 * whether that can be merged with its predecessor or its successor.
 * Or both (it neatly fills a hole).
 *
 * In most cases - when called for mmap, brk or mremap - [addr,end) is
 * certain not to be mapped by the time vma_merge is called; but when
 * called for mprotect, it is certain to be already mapped (either at
 * an offset within prev, or at the start of next), and the flags of
 * this area are about to be changed to vm_flags - and the no-change
 * case has already been eliminated.
 *
 * The following mprotect cases have to be considered, where AAAA is
 * the area passed down from mprotect_fixup, never extending beyond one
 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
 *
 *     AAAA             AAAA                AAAA          AAAA
 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
 *    cannot merge    might become    might become    might become
 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
 *    mremap move:                                    PPPPNNNNNNNN 8
 *        AAAA
 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
 *    might become    case 1 below    case 2 below    case 3 below
 *
 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
 */
struct vm_area_struct *vma_merge(struct mm_struct *mm,
			struct vm_area_struct *prev, unsigned long addr,
			unsigned long end, unsigned long vm_flags,
		     	struct anon_vma *anon_vma, struct file *file,
			pgoff_t pgoff, struct mempolicy *policy)
{
	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
	struct vm_area_struct *area, *next;
803
	int err;
Linus Torvalds's avatar
Linus Torvalds committed
804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834

	/*
	 * We later require that vma->vm_flags == vm_flags,
	 * so this tests vma->vm_flags & VM_SPECIAL, too.
	 */
	if (vm_flags & VM_SPECIAL)
		return NULL;

	if (prev)
		next = prev->vm_next;
	else
		next = mm->mmap;
	area = next;
	if (next && next->vm_end == end)		/* cases 6, 7, 8 */
		next = next->vm_next;

	/*
	 * Can it merge with the predecessor?
	 */
	if (prev && prev->vm_end == addr &&
  			mpol_equal(vma_policy(prev), policy) &&
			can_vma_merge_after(prev, vm_flags,
						anon_vma, file, pgoff)) {
		/*
		 * OK, it can.  Can we now merge in the successor as well?
		 */
		if (next && end == next->vm_start &&
				mpol_equal(policy, vma_policy(next)) &&
				can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen) &&
				is_mergeable_anon_vma(prev->anon_vma,
Shaohua Li's avatar
Shaohua Li committed
835
						      next->anon_vma, NULL)) {
Linus Torvalds's avatar
Linus Torvalds committed
836
							/* cases 1, 6 */
837
			err = vma_adjust(prev, prev->vm_start,
Linus Torvalds's avatar
Linus Torvalds committed
838 839
				next->vm_end, prev->vm_pgoff, NULL);
		} else					/* cases 2, 5, 7 */
840
			err = vma_adjust(prev, prev->vm_start,
Linus Torvalds's avatar
Linus Torvalds committed
841
				end, prev->vm_pgoff, NULL);
842 843
		if (err)
			return NULL;
Andrea Arcangeli's avatar
Andrea Arcangeli committed
844
		khugepaged_enter_vma_merge(prev);
Linus Torvalds's avatar
Linus Torvalds committed
845 846 847 848 849 850 851 852 853 854 855
		return prev;
	}

	/*
	 * Can this new request be merged in front of next?
	 */
	if (next && end == next->vm_start &&
 			mpol_equal(policy, vma_policy(next)) &&
			can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen)) {
		if (prev && addr < prev->vm_end)	/* case 4 */
856
			err = vma_adjust(prev, prev->vm_start,
Linus Torvalds's avatar
Linus Torvalds committed
857 858
				addr, prev->vm_pgoff, NULL);
		else					/* cases 3, 8 */
859
			err = vma_adjust(area, addr, next->vm_end,
Linus Torvalds's avatar
Linus Torvalds committed
860
				next->vm_pgoff - pglen, NULL);
861 862
		if (err)
			return NULL;
Andrea Arcangeli's avatar
Andrea Arcangeli committed
863
		khugepaged_enter_vma_merge(area);
Linus Torvalds's avatar
Linus Torvalds committed
864 865 866 867 868 869
		return area;
	}

	return NULL;
}

870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924
/*
 * Rough compatbility check to quickly see if it's even worth looking
 * at sharing an anon_vma.
 *
 * They need to have the same vm_file, and the flags can only differ
 * in things that mprotect may change.
 *
 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
 * we can merge the two vma's. For example, we refuse to merge a vma if
 * there is a vm_ops->close() function, because that indicates that the
 * driver is doing some kind of reference counting. But that doesn't
 * really matter for the anon_vma sharing case.
 */
static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
{
	return a->vm_end == b->vm_start &&
		mpol_equal(vma_policy(a), vma_policy(b)) &&
		a->vm_file == b->vm_file &&
		!((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
		b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
}

/*
 * Do some basic sanity checking to see if we can re-use the anon_vma
 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
 * the same as 'old', the other will be the new one that is trying
 * to share the anon_vma.
 *
 * NOTE! This runs with mm_sem held for reading, so it is possible that
 * the anon_vma of 'old' is concurrently in the process of being set up
 * by another page fault trying to merge _that_. But that's ok: if it
 * is being set up, that automatically means that it will be a singleton
 * acceptable for merging, so we can do all of this optimistically. But
 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
 *
 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
 * is to return an anon_vma that is "complex" due to having gone through
 * a fork).
 *
 * We also make sure that the two vma's are compatible (adjacent,
 * and with the same memory policies). That's all stable, even with just
 * a read lock on the mm_sem.
 */
static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
{
	if (anon_vma_compatible(a, b)) {
		struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);

		if (anon_vma && list_is_singular(&old->anon_vma_chain))
			return anon_vma;
	}
	return NULL;
}

Linus Torvalds's avatar
Linus Torvalds committed
925 926 927 928 929 930 931 932 933 934
/*
 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
 * neighbouring vmas for a suitable anon_vma, before it goes off
 * to allocate a new anon_vma.  It checks because a repetitive
 * sequence of mprotects and faults may otherwise lead to distinct
 * anon_vmas being allocated, preventing vma merge in subsequent
 * mprotect.
 */
struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
{
935
	struct anon_vma *anon_vma;
Linus Torvalds's avatar
Linus Torvalds committed
936 937 938 939 940 941
	struct vm_area_struct *near;

	near = vma->vm_next;
	if (!near)
		goto try_prev;

942 943 944
	anon_vma = reusable_anon_vma(near, vma, near);
	if (anon_vma)
		return anon_vma;
Linus Torvalds's avatar
Linus Torvalds committed
945
try_prev:
946
	near = vma->vm_prev;
Linus Torvalds's avatar
Linus Torvalds committed
947 948 949
	if (!near)
		goto none;

950 951 952
	anon_vma = reusable_anon_vma(near, near, vma);
	if (anon_vma)
		return anon_vma;
Linus Torvalds's avatar
Linus Torvalds committed
953 954 955 956 957 958 959 960 961 962 963 964 965
none:
	/*
	 * There's no absolute need to look only at touching neighbours:
	 * we could search further afield for "compatible" anon_vmas.
	 * But it would probably just be a waste of time searching,
	 * or lead to too many vmas hanging off the same anon_vma.
	 * We're trying to allow mprotect remerging later on,
	 * not trying to minimize memory used for anon_vmas.
	 */
	return NULL;
}

#ifdef CONFIG_PROC_FS
966
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
Linus Torvalds's avatar
Linus Torvalds committed
967 968 969 970 971
						struct file *file, long pages)
{
	const unsigned long stack_flags
		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);

972 973
	mm->total_vm += pages;

Linus Torvalds's avatar
Linus Torvalds committed
974 975 976 977 978 979 980 981 982
	if (file) {
		mm->shared_vm += pages;
		if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
			mm->exec_vm += pages;
	} else if (flags & stack_flags)
		mm->stack_vm += pages;
}
#endif /* CONFIG_PROC_FS */

Al Viro's avatar
Al Viro committed
983 984 985 986 987 988 989 990 991 992 993 994 995
/*
 * If a hint addr is less than mmap_min_addr change hint to be as
 * low as possible but still greater than mmap_min_addr
 */
static inline unsigned long round_hint_to_min(unsigned long hint)
{
	hint &= PAGE_MASK;
	if (((void *)hint != NULL) &&
	    (hint < mmap_min_addr))
		return PAGE_ALIGN(mmap_min_addr);
	return hint;
}

Linus Torvalds's avatar
Linus Torvalds committed
996
/*
997
 * The caller must hold down_write(&current->mm->mmap_sem).
Linus Torvalds's avatar
Linus Torvalds committed
998 999
 */

1000
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
Linus Torvalds's avatar
Linus Torvalds committed
1001 1002 1003 1004 1005
			unsigned long len, unsigned long prot,
			unsigned long flags, unsigned long pgoff)
{
	struct mm_struct * mm = current->mm;
	struct inode *inode;
1006
	vm_flags_t vm_flags;
Linus Torvalds's avatar
Linus Torvalds committed
1007 1008 1009 1010 1011 1012 1013 1014

	/*
	 * Does the application expect PROT_READ to imply PROT_EXEC?
	 *
	 * (the exception is when the underlying filesystem is noexec
	 *  mounted, in which case we dont add PROT_EXEC.)
	 */
	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1015
		if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
Linus Torvalds's avatar
Linus Torvalds committed
1016 1017 1018 1019 1020
			prot |= PROT_EXEC;

	if (!len)
		return -EINVAL;

1021 1022 1023
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

Linus Torvalds's avatar
Linus Torvalds committed
1024 1025
	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
1026
	if (!len)
Linus Torvalds's avatar
Linus Torvalds committed
1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050
		return -ENOMEM;

	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
               return -EOVERFLOW;

	/* Too many mappings? */
	if (mm->map_count > sysctl_max_map_count)
		return -ENOMEM;

	/* Obtain the address to map to. we verify (or select) it and ensure
	 * that it represents a valid section of the address space.
	 */
	addr = get_unmapped_area(file, addr, len, pgoff, flags);
	if (addr & ~PAGE_MASK)
		return addr;

	/* Do simple checking here so the lower-level routines won't have
	 * to. we assume access permissions have been handled by the open
	 * of the memory object, so we don't do any here.
	 */
	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;

Huang Shijie's avatar
Huang Shijie committed
1051
	if (flags & MAP_LOCKED)
Linus Torvalds's avatar
Linus Torvalds committed
1052 1053
		if (!can_do_mlock())
			return -EPERM;
1054

Linus Torvalds's avatar
Linus Torvalds committed
1055 1056 1057
	/* mlock MCL_FUTURE? */
	if (vm_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
1058 1059
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
Jiri Slaby's avatar
Jiri Slaby committed
1060
		lock_limit = rlimit(RLIMIT_MEMLOCK);
1061
		lock_limit >>= PAGE_SHIFT;
Linus Torvalds's avatar
Linus Torvalds committed
1062 1063 1064 1065
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			return -EAGAIN;
	}

1066
	inode = file ? file->f_path.dentry->d_inode : NULL;
Linus Torvalds's avatar
Linus Torvalds committed
1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094

	if (file) {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
			if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
				return -EACCES;

			/*
			 * Make sure we don't allow writing to an append-only
			 * file..
			 */
			if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
				return -EACCES;

			/*
			 * Make sure there are no mandatory locks on the file.
			 */
			if (locks_verify_locked(inode))
				return -EAGAIN;

			vm_flags |= VM_SHARED | VM_MAYSHARE;
			if (!(file->f_mode & FMODE_WRITE))
				vm_flags &= ~(VM_MAYWRITE | VM_SHARED);

			/* fall through */
		case MAP_PRIVATE:
			if (!(file->f_mode & FMODE_READ))
				return -EACCES;
1095
			if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
Linus Torvalds's avatar
Linus Torvalds committed
1096 1097 1098 1099 1100 1101 1102
				if (vm_flags & VM_EXEC)
					return -EPERM;
				vm_flags &= ~VM_MAYEXEC;
			}

			if (!file->f_op || !file->f_op->mmap)
				return -ENODEV;
Linus Torvalds's avatar
Linus Torvalds committed
1103 1104 1105 1106 1107 1108 1109 1110
			break;

		default:
			return -EINVAL;
		}
	} else {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
1111 1112 1113 1114
			/*
			 * Ignore pgoff.
			 */
			pgoff = 0;
Linus Torvalds's avatar
Linus Torvalds committed
1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127
			vm_flags |= VM_SHARED | VM_MAYSHARE;
			break;
		case MAP_PRIVATE:
			/*
			 * Set pgoff according to addr for anon_vma.
			 */
			pgoff = addr >> PAGE_SHIFT;
			break;
		default:
			return -EINVAL;
		}
	}

1128
	return mmap_region(file, addr, len, flags, vm_flags, pgoff);
Miklos Szeredi's avatar
Miklos Szeredi committed
1129
}
1130

1131 1132 1133 1134 1135 1136 1137 1138
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
		unsigned long, prot, unsigned long, flags,
		unsigned long, fd, unsigned long, pgoff)
{
	struct file *file = NULL;
	unsigned long retval = -EBADF;

	if (!(flags & MAP_ANONYMOUS)) {
Al Viro's avatar
Al Viro committed
1139
		audit_mmap_fd(fd, flags);
1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152
		if (unlikely(flags & MAP_HUGETLB))
			return -EINVAL;
		file = fget(fd);
		if (!file)
			goto out;
	} else if (flags & MAP_HUGETLB) {
		struct user_struct *user = NULL;
		/*
		 * VM_NORESERVE is used because the reservations will be
		 * taken when vm_ops->mmap() is called
		 * A dummy user value is used because we are not locking
		 * memory so no accounting is necessary
		 */
1153 1154 1155
		file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len,
						VM_NORESERVE, &user,
						HUGETLB_ANONHUGE_INODE);
1156 1157 1158 1159 1160 1161
		if (IS_ERR(file))
			return PTR_ERR(file);
	}

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

Al Viro's avatar
Al Viro committed
1162
	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1163 1164 1165 1166 1167 1168
	if (file)
		fput(file);
out:
	return retval;
}

Christoph Hellwig's avatar
Christoph Hellwig committed
1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192
#ifdef __ARCH_WANT_SYS_OLD_MMAP
struct mmap_arg_struct {
	unsigned long addr;
	unsigned long len;
	unsigned long prot;
	unsigned long flags;
	unsigned long fd;
	unsigned long offset;
};

SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
{
	struct mmap_arg_struct a;

	if (copy_from_user(&a, arg, sizeof(a)))
		return -EFAULT;
	if (a.offset & ~PAGE_MASK)
		return -EINVAL;

	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
			      a.offset >> PAGE_SHIFT);
}
#endif /* __ARCH_WANT_SYS_OLD_MMAP */

Alexey Dobriyan's avatar
Alexey Dobriyan committed
1193 1194 1195 1196 1197 1198 1199 1200
/*
 * Some shared mappigns will want the pages marked read-only
 * to track write events. If so, we'll downgrade vm_page_prot
 * to the private version (using protection_map[] without the
 * VM_SHARED bit).
 */
int vma_wants_writenotify(struct vm_area_struct *vma)
{
1201
	vm_flags_t vm_flags = vma->vm_flags;
Alexey Dobriyan's avatar
Alexey Dobriyan committed
1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212

	/* If it was private or non-writable, the write bit is already clear */
	if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
		return 0;

	/* The backer wishes to know when pages are first written to? */
	if (vma->vm_ops && vma->vm_ops->page_mkwrite)
		return 1;

	/* The open routine did something to the protections already? */
	if (pgprot_val(vma->vm_page_prot) !=
1213
	    pgprot_val(vm_get_page_prot(vm_flags)))
Alexey Dobriyan's avatar
Alexey Dobriyan committed
1214 1215 1216
		return 0;

	/* Specialty mapping? */
1217
	if (vm_flags & VM_PFNMAP)
Alexey Dobriyan's avatar
Alexey Dobriyan committed
1218 1219 1220 1221 1222 1223 1224
		return 0;

	/* Can the mapping track the dirty pages? */
	return vma->vm_file && vma->vm_file->f_mapping &&
		mapping_cap_account_dirty(vma->vm_file->f_mapping);
}

1225 1226
/*
 * We account for memory if it's a private writeable mapping,
1227
 * not hugepages and VM_NORESERVE wasn't set.
1228
 */
1229
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1230
{
1231 1232 1233 1234 1235 1236 1237
	/*
	 * hugetlb has its own accounting separate from the core VM
	 * VM_HUGETLB may not be set yet so we cannot check for that flag.
	 */
	if (file && is_file_hugepages(file))
		return 0;

1238 1239 1240
	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
}

Miklos Szeredi's avatar
Miklos Szeredi committed
1241 1242
unsigned long mmap_region(struct file *file, unsigned long addr,
			  unsigned long len, unsigned long flags,
1243
			  vm_flags_t vm_flags, unsigned long pgoff)
Miklos Szeredi's avatar
Miklos Szeredi committed
1244 1245 1246 1247 1248 1249 1250 1251 1252
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev;
	int correct_wcount = 0;
	int error;
	struct rb_node **rb_link, *rb_parent;
	unsigned long charged = 0;
	struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;

Linus Torvalds's avatar
Linus Torvalds committed
1253 1254 1255
	/* Clear old maps */
	error = -ENOMEM;
munmap_back:
1256
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
Linus Torvalds's avatar
Linus Torvalds committed
1257 1258 1259 1260 1261 1262
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

	/* Check against address space limit. */
akpm@osdl.org's avatar
akpm@osdl.org committed
1263
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
Linus Torvalds's avatar
Linus Torvalds committed
1264 1265
		return -ENOMEM;

1266 1267
	/*
	 * Set 'VM_NORESERVE' if we should not account for the
1268
	 * memory use of this mapping.
1269
	 */
1270