nommu.c 46.5 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8
/*
 *  linux/mm/nommu.c
 *
 *  Replacement code for mm functions to support CPU's that don't
 *  have any form of memory management unit (thus no virtual memory).
 *
 *  See Documentation/nommu-mmap.txt
 *
9
 *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
L
Linus Torvalds 已提交
10 11 12
 *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
 *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
 *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
13
 *  Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org>
L
Linus Torvalds 已提交
14 15
 */

16
#include <linux/module.h>
L
Linus Torvalds 已提交
17 18 19 20 21 22 23 24
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/file.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
25
#include <linux/tracehook.h>
L
Linus Torvalds 已提交
26 27 28 29 30 31 32 33 34 35
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/mount.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/syscalls.h>

#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
36
#include <asm/mmu_context.h>
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58
#include "internal.h"

static inline __attribute__((format(printf, 1, 2)))
void no_printk(const char *fmt, ...)
{
}

#if 0
#define kenter(FMT, ...) \
	printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) \
	printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) \
	printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
#else
#define kenter(FMT, ...) \
	no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) \
	no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) \
	no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
#endif
L
Linus Torvalds 已提交
59 60 61 62 63

void *high_memory;
struct page *mem_map;
unsigned long max_mapnr;
unsigned long num_physpages;
H
Hugh Dickins 已提交
64
unsigned long highest_memmap_pfn;
65
struct percpu_counter vm_committed_as;
L
Linus Torvalds 已提交
66 67 68
int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
int sysctl_overcommit_ratio = 50; /* default is 50% */
int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
69
int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
L
Linus Torvalds 已提交
70 71
int heap_stack_gap = 0;

72
atomic_long_t mmap_pages_allocated;
73

L
Linus Torvalds 已提交
74
EXPORT_SYMBOL(mem_map);
75
EXPORT_SYMBOL(num_physpages);
L
Linus Torvalds 已提交
76

77 78 79 80
/* list of mapped, potentially shareable regions */
static struct kmem_cache *vm_region_jar;
struct rb_root nommu_region_tree = RB_ROOT;
DECLARE_RWSEM(nommu_region_sem);
L
Linus Torvalds 已提交
81

82
const struct vm_operations_struct generic_file_vm_ops = {
L
Linus Torvalds 已提交
83 84 85 86 87 88 89 90 91 92 93 94
};

/*
 * Return the total memory allocated for this pointer, not
 * just what the caller asked for.
 *
 * Doesn't have to be accurate, i.e. may have races.
 */
unsigned int kobjsize(const void *objp)
{
	struct page *page;

95 96 97 98
	/*
	 * If the object we have should not have ksize performed on it,
	 * return size of 0
	 */
99
	if (!objp || !virt_addr_valid(objp))
100 101 102 103 104 105 106 107
		return 0;

	page = virt_to_head_page(objp);

	/*
	 * If the allocator sets PageSlab, we know the pointer came from
	 * kmalloc().
	 */
L
Linus Torvalds 已提交
108 109 110
	if (PageSlab(page))
		return ksize(objp);

111 112 113 114 115 116 117 118 119 120 121 122 123 124
	/*
	 * If it's not a compound page, see if we have a matching VMA
	 * region. This test is intentionally done in reverse order,
	 * so if there's no VMA, we still fall through and hand back
	 * PAGE_SIZE for 0-order pages.
	 */
	if (!PageCompound(page)) {
		struct vm_area_struct *vma;

		vma = find_vma(current->mm, (unsigned long)objp);
		if (vma)
			return vma->vm_end - vma->vm_start;
	}

125 126
	/*
	 * The ksize() function is only guaranteed to work for pointers
127
	 * returned by kmalloc(). So handle arbitrary pointers here.
128
	 */
129
	return PAGE_SIZE << compound_order(page);
L
Linus Torvalds 已提交
130 131
}

N
Nick Piggin 已提交
132
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
H
Hugh Dickins 已提交
133
		     unsigned long start, int nr_pages, unsigned int foll_flags,
134
		     struct page **pages, struct vm_area_struct **vmas)
L
Linus Torvalds 已提交
135
{
136
	struct vm_area_struct *vma;
137 138 139 140
	unsigned long vm_flags;
	int i;

	/* calculate required read or write permissions.
H
Hugh Dickins 已提交
141
	 * If FOLL_FORCE is set, we only require the "MAY" flags.
142
	 */
H
Hugh Dickins 已提交
143 144 145 146
	vm_flags  = (foll_flags & FOLL_WRITE) ?
			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= (foll_flags & FOLL_FORCE) ?
			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
147

148
	for (i = 0; i < nr_pages; i++) {
149
		vma = find_vma(mm, start);
150 151 152 153
		if (!vma)
			goto finish_or_fault;

		/* protect what we can, including chardevs */
H
Hugh Dickins 已提交
154 155
		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
		    !(vm_flags & vma->vm_flags))
156
			goto finish_or_fault;
157

L
Linus Torvalds 已提交
158 159 160 161 162 163
		if (pages) {
			pages[i] = virt_to_page(start);
			if (pages[i])
				page_cache_get(pages[i]);
		}
		if (vmas)
164
			vmas[i] = vma;
L
Linus Torvalds 已提交
165 166
		start += PAGE_SIZE;
	}
167 168 169 170 171

	return i;

finish_or_fault:
	return i ? : -EFAULT;
L
Linus Torvalds 已提交
172
}
N
Nick Piggin 已提交
173 174 175 176 177 178 179 180 181

/*
 * get a list of pages in an address range belonging to the specified process
 * and indicate the VMA that covers each page
 * - this is potentially dodgy as we may end incrementing the page count of a
 *   slab page or a secondary page from a compound page
 * - don't permit access to VMAs that don't support it, such as I/O mappings
 */
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
182
	unsigned long start, int nr_pages, int write, int force,
N
Nick Piggin 已提交
183 184 185 186 187
	struct page **pages, struct vm_area_struct **vmas)
{
	int flags = 0;

	if (write)
H
Hugh Dickins 已提交
188
		flags |= FOLL_WRITE;
N
Nick Piggin 已提交
189
	if (force)
H
Hugh Dickins 已提交
190
		flags |= FOLL_FORCE;
N
Nick Piggin 已提交
191

192
	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
N
Nick Piggin 已提交
193
}
194 195
EXPORT_SYMBOL(get_user_pages);

P
Paul Mundt 已提交
196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216
/**
 * follow_pfn - look up PFN at a user virtual address
 * @vma: memory mapping
 * @address: user virtual address
 * @pfn: location to store found PFN
 *
 * Only IO mappings and raw PFN mappings are allowed.
 *
 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 */
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
	unsigned long *pfn)
{
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		return -EINVAL;

	*pfn = address >> PAGE_SHIFT;
	return 0;
}
EXPORT_SYMBOL(follow_pfn);

L
Linus Torvalds 已提交
217 218 219
DEFINE_RWLOCK(vmlist_lock);
struct vm_struct *vmlist;

220
void vfree(const void *addr)
L
Linus Torvalds 已提交
221 222 223
{
	kfree(addr);
}
224
EXPORT_SYMBOL(vfree);
L
Linus Torvalds 已提交
225

A
Al Viro 已提交
226
void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
L
Linus Torvalds 已提交
227 228
{
	/*
229 230
	 *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
	 * returns only a logical address.
L
Linus Torvalds 已提交
231
	 */
232
	return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
L
Linus Torvalds 已提交
233
}
234
EXPORT_SYMBOL(__vmalloc);
L
Linus Torvalds 已提交
235

236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255
void *vmalloc_user(unsigned long size)
{
	void *ret;

	ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
			PAGE_KERNEL);
	if (ret) {
		struct vm_area_struct *vma;

		down_write(&current->mm->mmap_sem);
		vma = find_vma(current->mm, (unsigned long)ret);
		if (vma)
			vma->vm_flags |= VM_USERMAP;
		up_write(&current->mm->mmap_sem);
	}

	return ret;
}
EXPORT_SYMBOL(vmalloc_user);

256
struct page *vmalloc_to_page(const void *addr)
L
Linus Torvalds 已提交
257 258 259
{
	return virt_to_page(addr);
}
260
EXPORT_SYMBOL(vmalloc_to_page);
L
Linus Torvalds 已提交
261

262
unsigned long vmalloc_to_pfn(const void *addr)
L
Linus Torvalds 已提交
263 264 265
{
	return page_to_pfn(virt_to_page(addr));
}
266
EXPORT_SYMBOL(vmalloc_to_pfn);
L
Linus Torvalds 已提交
267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291

long vread(char *buf, char *addr, unsigned long count)
{
	memcpy(buf, addr, count);
	return count;
}

long vwrite(char *buf, char *addr, unsigned long count)
{
	/* Don't allow overflow */
	if ((unsigned long) addr + count < count)
		count = -(unsigned long) addr;

	memcpy(addr, buf, count);
	return(count);
}

/*
 *	vmalloc  -  allocate virtually continguos memory
 *
 *	@size:		allocation size
 *
 *	Allocate enough pages to cover @size from the page level
 *	allocator and map them into continguos kernel virtual space.
 *
292
 *	For tight control over page level allocator and protection flags
L
Linus Torvalds 已提交
293 294 295 296 297 298
 *	use __vmalloc() instead.
 */
void *vmalloc(unsigned long size)
{
       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
}
299 300 301 302 303 304 305
EXPORT_SYMBOL(vmalloc);

void *vmalloc_node(unsigned long size, int node)
{
	return vmalloc(size);
}
EXPORT_SYMBOL(vmalloc_node);
L
Linus Torvalds 已提交
306

P
Paul Mundt 已提交
307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327
#ifndef PAGE_KERNEL_EXEC
# define PAGE_KERNEL_EXEC PAGE_KERNEL
#endif

/**
 *	vmalloc_exec  -  allocate virtually contiguous, executable memory
 *	@size:		allocation size
 *
 *	Kernel-internal function to allocate enough pages to cover @size
 *	the page level allocator and map them into contiguous and
 *	executable kernel virtual space.
 *
 *	For tight control over page level allocator and protection flags
 *	use __vmalloc() instead.
 */

void *vmalloc_exec(unsigned long size)
{
	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
}

328 329
/**
 * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
L
Linus Torvalds 已提交
330 331 332 333 334 335 336 337 338
 *	@size:		allocation size
 *
 *	Allocate enough 32bit PA addressable pages to cover @size from the
 *	page level allocator and map them into continguos kernel virtual space.
 */
void *vmalloc_32(unsigned long size)
{
	return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
}
339 340 341 342 343 344 345 346
EXPORT_SYMBOL(vmalloc_32);

/**
 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 *	@size:		allocation size
 *
 * The resulting memory area is 32bit addressable and zeroed so it can be
 * mapped to userspace without leaking data.
347 348 349
 *
 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 * remap_vmalloc_range() are permissible.
350 351 352
 */
void *vmalloc_32_user(unsigned long size)
{
353 354 355 356 357
	/*
	 * We'll have to sort out the ZONE_DMA bits for 64-bit,
	 * but for now this can simply use vmalloc_user() directly.
	 */
	return vmalloc_user(size);
358 359
}
EXPORT_SYMBOL(vmalloc_32_user);
L
Linus Torvalds 已提交
360 361 362 363 364 365

void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
{
	BUG();
	return NULL;
}
366
EXPORT_SYMBOL(vmap);
L
Linus Torvalds 已提交
367

368
void vunmap(const void *addr)
L
Linus Torvalds 已提交
369 370 371
{
	BUG();
}
372
EXPORT_SYMBOL(vunmap);
L
Linus Torvalds 已提交
373

374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391
void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
{
	BUG();
	return NULL;
}
EXPORT_SYMBOL(vm_map_ram);

void vm_unmap_ram(const void *mem, unsigned int count)
{
	BUG();
}
EXPORT_SYMBOL(vm_unmap_ram);

void vm_unmap_aliases(void)
{
}
EXPORT_SYMBOL_GPL(vm_unmap_aliases);

392 393 394 395 396 397 398 399
/*
 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 * have one.
 */
void  __attribute__((weak)) vmalloc_sync_all(void)
{
}

400 401 402 403 404 405 406
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
		   struct page *page)
{
	return -EINVAL;
}
EXPORT_SYMBOL(vm_insert_page);

L
Linus Torvalds 已提交
407 408 409 410 411 412 413
/*
 *  sys_brk() for the most part doesn't need the global kernel
 *  lock, except when an application is doing something nasty
 *  like trying to un-brk an area that has already been mapped
 *  to a regular file.  in this case, the unmapping will need
 *  to invoke file system routines that need the global lock.
 */
414
SYSCALL_DEFINE1(brk, unsigned long, brk)
L
Linus Torvalds 已提交
415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434
{
	struct mm_struct *mm = current->mm;

	if (brk < mm->start_brk || brk > mm->context.end_brk)
		return mm->brk;

	if (mm->brk == brk)
		return mm->brk;

	/*
	 * Always allow shrinking brk
	 */
	if (brk <= mm->brk) {
		mm->brk = brk;
		return brk;
	}

	/*
	 * Ok, looks good - let it rip.
	 */
435
	flush_icache_range(mm->brk, brk);
L
Linus Torvalds 已提交
436 437 438
	return mm->brk = brk;
}

439 440 441 442
/*
 * initialise the VMA and region record slabs
 */
void __init mmap_init(void)
L
Linus Torvalds 已提交
443
{
444 445 446 447
	int ret;

	ret = percpu_counter_init(&vm_committed_as, 0);
	VM_BUG_ON(ret);
448
	vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
L
Linus Torvalds 已提交
449 450
}

451
/*
452 453
 * validate the region tree
 * - the caller must hold the region lock
454
 */
455 456
#ifdef CONFIG_DEBUG_NOMMU_REGIONS
static noinline void validate_nommu_regions(void)
457
{
458 459
	struct vm_region *region, *last;
	struct rb_node *p, *lastp;
460

461 462 463 464 465
	lastp = rb_first(&nommu_region_tree);
	if (!lastp)
		return;

	last = rb_entry(lastp, struct vm_region, vm_rb);
466 467
	BUG_ON(unlikely(last->vm_end <= last->vm_start));
	BUG_ON(unlikely(last->vm_top < last->vm_end));
468 469 470 471 472

	while ((p = rb_next(lastp))) {
		region = rb_entry(p, struct vm_region, vm_rb);
		last = rb_entry(lastp, struct vm_region, vm_rb);

473 474 475
		BUG_ON(unlikely(region->vm_end <= region->vm_start));
		BUG_ON(unlikely(region->vm_top < region->vm_end));
		BUG_ON(unlikely(region->vm_start < last->vm_top));
476

477 478
		lastp = p;
	}
479
}
480
#else
481 482 483
static void validate_nommu_regions(void)
{
}
484
#endif
485 486

/*
487
 * add a region into the global tree
488
 */
489
static void add_nommu_region(struct vm_region *region)
490
{
491 492
	struct vm_region *pregion;
	struct rb_node **p, *parent;
493

494 495 496 497 498 499 500 501 502 503 504 505 506 507 508
	validate_nommu_regions();

	parent = NULL;
	p = &nommu_region_tree.rb_node;
	while (*p) {
		parent = *p;
		pregion = rb_entry(parent, struct vm_region, vm_rb);
		if (region->vm_start < pregion->vm_start)
			p = &(*p)->rb_left;
		else if (region->vm_start > pregion->vm_start)
			p = &(*p)->rb_right;
		else if (pregion == region)
			return;
		else
			BUG();
509 510
	}

511 512
	rb_link_node(&region->vm_rb, parent, p);
	rb_insert_color(&region->vm_rb, &nommu_region_tree);
513

514
	validate_nommu_regions();
515 516
}

517
/*
518
 * delete a region from the global tree
519
 */
520
static void delete_nommu_region(struct vm_region *region)
521
{
522
	BUG_ON(!nommu_region_tree.rb_node);
523

524 525 526
	validate_nommu_regions();
	rb_erase(&region->vm_rb, &nommu_region_tree);
	validate_nommu_regions();
527 528
}

529
/*
530
 * free a contiguous series of pages
531
 */
532
static void free_page_series(unsigned long from, unsigned long to)
533
{
534 535 536 537
	for (; from < to; from += PAGE_SIZE) {
		struct page *page = virt_to_page(from);

		kdebug("- free %lx", from);
538
		atomic_long_dec(&mmap_pages_allocated);
539
		if (page_count(page) != 1)
540 541
			kdebug("free page %p: refcount not one: %d",
			       page, page_count(page));
542
		put_page(page);
543 544 545
	}
}

546
/*
547
 * release a reference to a region
548
 * - the caller must hold the region semaphore for writing, which this releases
549
 * - the region may not have been added to the tree yet, in which case vm_top
550
 *   will equal vm_start
551
 */
552 553
static void __put_nommu_region(struct vm_region *region)
	__releases(nommu_region_sem)
L
Linus Torvalds 已提交
554
{
555
	kenter("%p{%d}", region, region->vm_usage);
L
Linus Torvalds 已提交
556

557
	BUG_ON(!nommu_region_tree.rb_node);
L
Linus Torvalds 已提交
558

559
	if (--region->vm_usage == 0) {
560
		if (region->vm_top > region->vm_start)
561 562 563 564 565 566 567 568 569 570
			delete_nommu_region(region);
		up_write(&nommu_region_sem);

		if (region->vm_file)
			fput(region->vm_file);

		/* IO memory and memory shared directly out of the pagecache
		 * from ramfs/tmpfs mustn't be released here */
		if (region->vm_flags & VM_MAPPED_COPY) {
			kdebug("free series");
571
			free_page_series(region->vm_start, region->vm_top);
572 573 574 575
		}
		kmem_cache_free(vm_region_jar, region);
	} else {
		up_write(&nommu_region_sem);
L
Linus Torvalds 已提交
576
	}
577
}
L
Linus Torvalds 已提交
578

579 580 581 582 583 584 585
/*
 * release a reference to a region
 */
static void put_nommu_region(struct vm_region *region)
{
	down_write(&nommu_region_sem);
	__put_nommu_region(region);
L
Linus Torvalds 已提交
586 587
}

588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603
/*
 * update protection on a vma
 */
static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
{
#ifdef CONFIG_MPU
	struct mm_struct *mm = vma->vm_mm;
	long start = vma->vm_start & PAGE_MASK;
	while (start < vma->vm_end) {
		protect_page(mm, start, flags);
		start += PAGE_SIZE;
	}
	update_protections(mm);
#endif
}

604
/*
605 606 607 608
 * add a VMA into a process's mm_struct in the appropriate place in the list
 * and tree and add to the address space's page tree also if not an anonymous
 * page
 * - should be called with mm->mmap_sem held writelocked
609
 */
610
static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
611
{
612
	struct vm_area_struct *pvma, **pp;
L
Linus Torvalds 已提交
613
	struct address_space *mapping;
614 615 616 617 618 619 620 621
	struct rb_node **p, *parent;

	kenter(",%p", vma);

	BUG_ON(!vma->vm_region);

	mm->map_count++;
	vma->vm_mm = mm;
L
Linus Torvalds 已提交
622

623 624
	protect_vma(vma, vma->vm_flags);

L
Linus Torvalds 已提交
625 626 627 628 629 630 631 632 633
	/* add the VMA to the mapping */
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;

		flush_dcache_mmap_lock(mapping);
		vma_prio_tree_insert(vma, &mapping->i_mmap);
		flush_dcache_mmap_unlock(mapping);
	}

634 635 636
	/* add the VMA to the tree */
	parent = NULL;
	p = &mm->mm_rb.rb_node;
L
Linus Torvalds 已提交
637 638 639 640
	while (*p) {
		parent = *p;
		pvma = rb_entry(parent, struct vm_area_struct, vm_rb);

641 642 643
		/* sort by: start addr, end addr, VMA struct addr in that order
		 * (the latter is necessary as we may get identical VMAs) */
		if (vma->vm_start < pvma->vm_start)
L
Linus Torvalds 已提交
644
			p = &(*p)->rb_left;
645
		else if (vma->vm_start > pvma->vm_start)
L
Linus Torvalds 已提交
646
			p = &(*p)->rb_right;
647 648 649 650 651 652 653 654 655 656
		else if (vma->vm_end < pvma->vm_end)
			p = &(*p)->rb_left;
		else if (vma->vm_end > pvma->vm_end)
			p = &(*p)->rb_right;
		else if (vma < pvma)
			p = &(*p)->rb_left;
		else if (vma > pvma)
			p = &(*p)->rb_right;
		else
			BUG();
L
Linus Torvalds 已提交
657 658 659
	}

	rb_link_node(&vma->vm_rb, parent, p);
660 661 662 663 664 665 666 667 668 669 670 671 672 673
	rb_insert_color(&vma->vm_rb, &mm->mm_rb);

	/* add VMA to the VMA list also */
	for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
		if (pvma->vm_start > vma->vm_start)
			break;
		if (pvma->vm_start < vma->vm_start)
			continue;
		if (pvma->vm_end < vma->vm_end)
			break;
	}

	vma->vm_next = *pp;
	*pp = vma;
L
Linus Torvalds 已提交
674 675
}

676
/*
677
 * delete a VMA from its owning mm_struct and address space
678
 */
679
static void delete_vma_from_mm(struct vm_area_struct *vma)
L
Linus Torvalds 已提交
680
{
681
	struct vm_area_struct **pp;
L
Linus Torvalds 已提交
682
	struct address_space *mapping;
683 684 685 686
	struct mm_struct *mm = vma->vm_mm;

	kenter("%p", vma);

687 688
	protect_vma(vma, 0);

689 690 691
	mm->map_count--;
	if (mm->mmap_cache == vma)
		mm->mmap_cache = NULL;
L
Linus Torvalds 已提交
692 693 694 695 696 697 698 699 700 701

	/* remove the VMA from the mapping */
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;

		flush_dcache_mmap_lock(mapping);
		vma_prio_tree_remove(vma, &mapping->i_mmap);
		flush_dcache_mmap_unlock(mapping);
	}

702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810
	/* remove from the MM's tree and list */
	rb_erase(&vma->vm_rb, &mm->mm_rb);
	for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
		if (*pp == vma) {
			*pp = vma->vm_next;
			break;
		}
	}

	vma->vm_mm = NULL;
}

/*
 * destroy a VMA record
 */
static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
{
	kenter("%p", vma);
	if (vma->vm_ops && vma->vm_ops->close)
		vma->vm_ops->close(vma);
	if (vma->vm_file) {
		fput(vma->vm_file);
		if (vma->vm_flags & VM_EXECUTABLE)
			removed_exe_file_vma(mm);
	}
	put_nommu_region(vma->vm_region);
	kmem_cache_free(vm_area_cachep, vma);
}

/*
 * look up the first VMA in which addr resides, NULL if none
 * - should be called with mm->mmap_sem at least held readlocked
 */
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
	struct vm_area_struct *vma;
	struct rb_node *n = mm->mm_rb.rb_node;

	/* check the cache first */
	vma = mm->mmap_cache;
	if (vma && vma->vm_start <= addr && vma->vm_end > addr)
		return vma;

	/* trawl the tree (there may be multiple mappings in which addr
	 * resides) */
	for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
		vma = rb_entry(n, struct vm_area_struct, vm_rb);
		if (vma->vm_start > addr)
			return NULL;
		if (vma->vm_end > addr) {
			mm->mmap_cache = vma;
			return vma;
		}
	}

	return NULL;
}
EXPORT_SYMBOL(find_vma);

/*
 * find a VMA
 * - we don't extend stack VMAs under NOMMU conditions
 */
struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
{
	return find_vma(mm, addr);
}

/*
 * expand a stack to a given address
 * - not supported under NOMMU conditions
 */
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
	return -ENOMEM;
}

/*
 * look up the first VMA exactly that exactly matches addr
 * - should be called with mm->mmap_sem at least held readlocked
 */
static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
					     unsigned long addr,
					     unsigned long len)
{
	struct vm_area_struct *vma;
	struct rb_node *n = mm->mm_rb.rb_node;
	unsigned long end = addr + len;

	/* check the cache first */
	vma = mm->mmap_cache;
	if (vma && vma->vm_start == addr && vma->vm_end == end)
		return vma;

	/* trawl the tree (there may be multiple mappings in which addr
	 * resides) */
	for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
		vma = rb_entry(n, struct vm_area_struct, vm_rb);
		if (vma->vm_start < addr)
			continue;
		if (vma->vm_start > addr)
			return NULL;
		if (vma->vm_end == end) {
			mm->mmap_cache = vma;
			return vma;
		}
	}

	return NULL;
L
Linus Torvalds 已提交
811 812 813 814 815 816 817 818 819 820 821 822 823 824
}

/*
 * determine whether a mapping should be permitted and, if so, what sort of
 * mapping we're capable of supporting
 */
static int validate_mmap_request(struct file *file,
				 unsigned long addr,
				 unsigned long len,
				 unsigned long prot,
				 unsigned long flags,
				 unsigned long pgoff,
				 unsigned long *_capabilities)
{
825
	unsigned long capabilities, rlen;
L
Linus Torvalds 已提交
826 827 828 829
	unsigned long reqprot = prot;
	int ret;

	/* do the simple checks first */
830
	if (flags & MAP_FIXED) {
L
Linus Torvalds 已提交
831 832 833 834 835 836 837 838 839 840
		printk(KERN_DEBUG
		       "%d: Can't do fixed-address/overlay mmap of RAM\n",
		       current->pid);
		return -EINVAL;
	}

	if ((flags & MAP_TYPE) != MAP_PRIVATE &&
	    (flags & MAP_TYPE) != MAP_SHARED)
		return -EINVAL;

841
	if (!len)
L
Linus Torvalds 已提交
842 843
		return -EINVAL;

844
	/* Careful about overflows.. */
845 846
	rlen = PAGE_ALIGN(len);
	if (!rlen || rlen > TASK_SIZE)
847 848
		return -ENOMEM;

L
Linus Torvalds 已提交
849
	/* offset overflow? */
850
	if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
851
		return -EOVERFLOW;
L
Linus Torvalds 已提交
852 853 854 855 856 857 858 859 860 861 862 863 864 865 866

	if (file) {
		/* validate file mapping requests */
		struct address_space *mapping;

		/* files must support mmap */
		if (!file->f_op || !file->f_op->mmap)
			return -ENODEV;

		/* work out if what we've got could possibly be shared
		 * - we support chardevs that provide their own "memory"
		 * - we support files/blockdevs that are memory backed
		 */
		mapping = file->f_mapping;
		if (!mapping)
J
Josef Sipek 已提交
867
			mapping = file->f_path.dentry->d_inode->i_mapping;
L
Linus Torvalds 已提交
868 869 870 871 872 873 874 875

		capabilities = 0;
		if (mapping && mapping->backing_dev_info)
			capabilities = mapping->backing_dev_info->capabilities;

		if (!capabilities) {
			/* no explicit capabilities set, so assume some
			 * defaults */
J
Josef Sipek 已提交
876
			switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
L
Linus Torvalds 已提交
877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900
			case S_IFREG:
			case S_IFBLK:
				capabilities = BDI_CAP_MAP_COPY;
				break;

			case S_IFCHR:
				capabilities =
					BDI_CAP_MAP_DIRECT |
					BDI_CAP_READ_MAP |
					BDI_CAP_WRITE_MAP;
				break;

			default:
				return -EINVAL;
			}
		}

		/* eliminate any capabilities that we can't support on this
		 * device */
		if (!file->f_op->get_unmapped_area)
			capabilities &= ~BDI_CAP_MAP_DIRECT;
		if (!file->f_op->read)
			capabilities &= ~BDI_CAP_MAP_COPY;

901 902 903 904
		/* The file shall have been opened with read permission. */
		if (!(file->f_mode & FMODE_READ))
			return -EACCES;

L
Linus Torvalds 已提交
905 906 907 908 909 910
		if (flags & MAP_SHARED) {
			/* do checks for writing, appending and locking */
			if ((prot & PROT_WRITE) &&
			    !(file->f_mode & FMODE_WRITE))
				return -EACCES;

J
Josef Sipek 已提交
911
			if (IS_APPEND(file->f_path.dentry->d_inode) &&
L
Linus Torvalds 已提交
912 913 914
			    (file->f_mode & FMODE_WRITE))
				return -EACCES;

J
Josef Sipek 已提交
915
			if (locks_verify_locked(file->f_path.dentry->d_inode))
L
Linus Torvalds 已提交
916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945
				return -EAGAIN;

			if (!(capabilities & BDI_CAP_MAP_DIRECT))
				return -ENODEV;

			if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
			    ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
			    ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
			    ) {
				printk("MAP_SHARED not completely supported on !MMU\n");
				return -EINVAL;
			}

			/* we mustn't privatise shared mappings */
			capabilities &= ~BDI_CAP_MAP_COPY;
		}
		else {
			/* we're going to read the file into private memory we
			 * allocate */
			if (!(capabilities & BDI_CAP_MAP_COPY))
				return -ENODEV;

			/* we don't permit a private writable mapping to be
			 * shared with the backing device */
			if (prot & PROT_WRITE)
				capabilities &= ~BDI_CAP_MAP_DIRECT;
		}

		/* handle executable mappings and implied executable
		 * mappings */
J
Josef Sipek 已提交
946
		if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
L
Linus Torvalds 已提交
947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977
			if (prot & PROT_EXEC)
				return -EPERM;
		}
		else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
			/* handle implication of PROT_EXEC by PROT_READ */
			if (current->personality & READ_IMPLIES_EXEC) {
				if (capabilities & BDI_CAP_EXEC_MAP)
					prot |= PROT_EXEC;
			}
		}
		else if ((prot & PROT_READ) &&
			 (prot & PROT_EXEC) &&
			 !(capabilities & BDI_CAP_EXEC_MAP)
			 ) {
			/* backing file is not executable, try to copy */
			capabilities &= ~BDI_CAP_MAP_DIRECT;
		}
	}
	else {
		/* anonymous mappings are always memory backed and can be
		 * privately mapped
		 */
		capabilities = BDI_CAP_MAP_COPY;

		/* handle PROT_EXEC implication by PROT_READ */
		if ((prot & PROT_READ) &&
		    (current->personality & READ_IMPLIES_EXEC))
			prot |= PROT_EXEC;
	}

	/* allow the security API to have its say */
978
	ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
L
Linus Torvalds 已提交
979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020
	if (ret < 0)
		return ret;

	/* looks okay */
	*_capabilities = capabilities;
	return 0;
}

/*
 * we've determined that we can make the mapping, now translate what we
 * now know into VMA flags
 */
static unsigned long determine_vm_flags(struct file *file,
					unsigned long prot,
					unsigned long flags,
					unsigned long capabilities)
{
	unsigned long vm_flags;

	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
	vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
	/* vm_flags |= mm->def_flags; */

	if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
		/* attempt to share read-only copies of mapped file chunks */
		if (file && !(prot & PROT_WRITE))
			vm_flags |= VM_MAYSHARE;
	}
	else {
		/* overlay a shareable mapping on the backing device or inode
		 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
		 * romfs/cramfs */
		if (flags & MAP_SHARED)
			vm_flags |= VM_MAYSHARE | VM_SHARED;
		else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
			vm_flags |= VM_MAYSHARE;
	}

	/* refuse to let anyone share private mappings with this process if
	 * it's being traced - otherwise breakpoints set in it may interfere
	 * with another untraced process
	 */
1021
	if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
L
Linus Torvalds 已提交
1022 1023 1024 1025 1026 1027
		vm_flags &= ~VM_MAYSHARE;

	return vm_flags;
}

/*
1028 1029
 * set up a shared mapping on a file (the driver or filesystem provides and
 * pins the storage)
L
Linus Torvalds 已提交
1030
 */
1031
static int do_mmap_shared_file(struct vm_area_struct *vma)
L
Linus Torvalds 已提交
1032 1033 1034 1035
{
	int ret;

	ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1036 1037
	if (ret == 0) {
		vma->vm_region->vm_top = vma->vm_region->vm_end;
1038
		return 0;
1039
	}
L
Linus Torvalds 已提交
1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052
	if (ret != -ENOSYS)
		return ret;

	/* getting an ENOSYS error indicates that direct mmap isn't
	 * possible (as opposed to tried but failed) so we'll fall
	 * through to making a private copy of the data and mapping
	 * that if we can */
	return -ENODEV;
}

/*
 * set up a private mapping or an anonymous shared mapping
 */
1053 1054
static int do_mmap_private(struct vm_area_struct *vma,
			   struct vm_region *region,
1055 1056
			   unsigned long len,
			   unsigned long capabilities)
L
Linus Torvalds 已提交
1057
{
1058 1059
	struct page *pages;
	unsigned long total, point, n, rlen;
L
Linus Torvalds 已提交
1060
	void *base;
1061
	int ret, order;
L
Linus Torvalds 已提交
1062 1063 1064 1065 1066

	/* invoke the file's mapping function so that it can keep track of
	 * shared mappings on devices or memory
	 * - VM_MAYSHARE will be set if it may attempt to share
	 */
1067
	if (capabilities & BDI_CAP_MAP_DIRECT) {
L
Linus Torvalds 已提交
1068
		ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1069
		if (ret == 0) {
L
Linus Torvalds 已提交
1070
			/* shouldn't return success if we're not sharing */
1071 1072
			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
			vma->vm_region->vm_top = vma->vm_region->vm_end;
1073
			return 0;
L
Linus Torvalds 已提交
1074
		}
1075 1076
		if (ret != -ENOSYS)
			return ret;
L
Linus Torvalds 已提交
1077 1078 1079 1080 1081 1082

		/* getting an ENOSYS error indicates that direct mmap isn't
		 * possible (as opposed to tried but failed) so we'll try to
		 * make a private copy of the data and map that instead */
	}

1083 1084
	rlen = PAGE_ALIGN(len);

L
Linus Torvalds 已提交
1085 1086 1087 1088
	/* allocate some memory to hold the mapping
	 * - note that this may not return a page-aligned address if the object
	 *   we're allocating is smaller than a page
	 */
1089 1090 1091 1092 1093
	order = get_order(rlen);
	kdebug("alloc order %d for %lx", order, len);

	pages = alloc_pages(GFP_KERNEL, order);
	if (!pages)
L
Linus Torvalds 已提交
1094 1095
		goto enomem;

1096
	total = 1 << order;
1097
	atomic_long_add(total, &mmap_pages_allocated);
1098 1099

	point = rlen >> PAGE_SHIFT;
1100 1101 1102 1103 1104 1105 1106 1107

	/* we allocated a power-of-2 sized page set, so we may want to trim off
	 * the excess */
	if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
		while (total > point) {
			order = ilog2(total - point);
			n = 1 << order;
			kdebug("shave %lu/%lu @%lu", n, total - point, total);
1108
			atomic_long_sub(n, &mmap_pages_allocated);
1109 1110 1111 1112
			total -= n;
			set_page_refcounted(pages + total);
			__free_pages(pages + total, order);
		}
1113 1114 1115 1116
	}

	for (point = 1; point < total; point++)
		set_page_refcounted(&pages[point]);
L
Linus Torvalds 已提交
1117

1118 1119 1120 1121
	base = page_address(pages);
	region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
	region->vm_start = (unsigned long) base;
	region->vm_end   = region->vm_start + rlen;
1122
	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1123 1124 1125

	vma->vm_start = region->vm_start;
	vma->vm_end   = region->vm_start + len;
L
Linus Torvalds 已提交
1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136

	if (vma->vm_file) {
		/* read the contents of a file into the copy */
		mm_segment_t old_fs;
		loff_t fpos;

		fpos = vma->vm_pgoff;
		fpos <<= PAGE_SHIFT;

		old_fs = get_fs();
		set_fs(KERNEL_DS);
1137
		ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
L
Linus Torvalds 已提交
1138 1139 1140 1141 1142 1143
		set_fs(old_fs);

		if (ret < 0)
			goto error_free;

		/* clear the last little bit */
1144 1145
		if (ret < rlen)
			memset(base + ret, 0, rlen - ret);
L
Linus Torvalds 已提交
1146 1147 1148 1149 1150 1151

	}

	return 0;

error_free:
1152 1153 1154
	free_page_series(region->vm_start, region->vm_end);
	region->vm_start = vma->vm_start = 0;
	region->vm_end   = vma->vm_end = 0;
1155
	region->vm_top   = 0;
L
Linus Torvalds 已提交
1156 1157 1158
	return ret;

enomem:
1159 1160
	printk("Allocation of length %lu from process %d (%s) failed\n",
	       len, current->pid, current->comm);
L
Linus Torvalds 已提交
1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174
	show_free_areas();
	return -ENOMEM;
}

/*
 * handle mapping creation for uClinux
 */
unsigned long do_mmap_pgoff(struct file *file,
			    unsigned long addr,
			    unsigned long len,
			    unsigned long prot,
			    unsigned long flags,
			    unsigned long pgoff)
{
1175 1176
	struct vm_area_struct *vma;
	struct vm_region *region;
L
Linus Torvalds 已提交
1177
	struct rb_node *rb;
1178
	unsigned long capabilities, vm_flags, result;
L
Linus Torvalds 已提交
1179 1180
	int ret;

1181 1182
	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);

L
Linus Torvalds 已提交
1183 1184 1185 1186
	/* decide whether we should attempt the mapping, and if so what sort of
	 * mapping */
	ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
				    &capabilities);
1187 1188
	if (ret < 0) {
		kleave(" = %d [val]", ret);
L
Linus Torvalds 已提交
1189
		return ret;
1190
	}
L
Linus Torvalds 已提交
1191

1192 1193 1194
	/* we ignore the address hint */
	addr = 0;

L
Linus Torvalds 已提交
1195 1196 1197 1198
	/* we've determined that we can make the mapping, now translate what we
	 * now know into VMA flags */
	vm_flags = determine_vm_flags(file, prot, flags, capabilities);

1199 1200 1201 1202 1203 1204 1205 1206
	/* we're going to need to record the mapping */
	region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
	if (!region)
		goto error_getting_region;

	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (!vma)
		goto error_getting_vma;
L
Linus Torvalds 已提交
1207

1208
	region->vm_usage = 1;
1209 1210 1211 1212 1213 1214
	region->vm_flags = vm_flags;
	region->vm_pgoff = pgoff;

	INIT_LIST_HEAD(&vma->anon_vma_node);
	vma->vm_flags = vm_flags;
	vma->vm_pgoff = pgoff;
L
Linus Torvalds 已提交
1215

1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229
	if (file) {
		region->vm_file = file;
		get_file(file);
		vma->vm_file = file;
		get_file(file);
		if (vm_flags & VM_EXECUTABLE) {
			added_exe_file_vma(current->mm);
			vma->vm_mm = current->mm;
		}
	}

	down_write(&nommu_region_sem);

	/* if we want to share, we need to check for regions created by other
L
Linus Torvalds 已提交
1230
	 * mmap() calls that overlap with our proposed mapping
1231
	 * - we can only share with a superset match on most regular files
L
Linus Torvalds 已提交
1232 1233 1234 1235 1236 1237
	 * - shared mappings on character devices and memory backed files are
	 *   permitted to overlap inexactly as far as we are concerned for in
	 *   these cases, sharing is handled in the driver or filesystem rather
	 *   than here
	 */
	if (vm_flags & VM_MAYSHARE) {
1238 1239
		struct vm_region *pregion;
		unsigned long pglen, rpglen, pgend, rpgend, start;
L
Linus Torvalds 已提交
1240

1241 1242
		pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		pgend = pgoff + pglen;
1243

1244 1245
		for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
			pregion = rb_entry(rb, struct vm_region, vm_rb);
L
Linus Torvalds 已提交
1246

1247
			if (!(pregion->vm_flags & VM_MAYSHARE))
L
Linus Torvalds 已提交
1248 1249 1250
				continue;

			/* search for overlapping mappings on the same file */
1251 1252
			if (pregion->vm_file->f_path.dentry->d_inode !=
			    file->f_path.dentry->d_inode)
L
Linus Torvalds 已提交
1253 1254
				continue;

1255
			if (pregion->vm_pgoff >= pgend)
L
Linus Torvalds 已提交
1256 1257
				continue;

1258 1259 1260 1261
			rpglen = pregion->vm_end - pregion->vm_start;
			rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
			rpgend = pregion->vm_pgoff + rpglen;
			if (pgoff >= rpgend)
L
Linus Torvalds 已提交
1262 1263
				continue;

1264 1265 1266 1267 1268
			/* handle inexactly overlapping matches between
			 * mappings */
			if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
			    !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
				/* new mapping is not a subset of the region */
L
Linus Torvalds 已提交
1269 1270 1271 1272 1273
				if (!(capabilities & BDI_CAP_MAP_DIRECT))
					goto sharing_violation;
				continue;
			}

1274
			/* we've found a region we can share */
1275
			pregion->vm_usage++;
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291
			vma->vm_region = pregion;
			start = pregion->vm_start;
			start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
			vma->vm_start = start;
			vma->vm_end = start + len;

			if (pregion->vm_flags & VM_MAPPED_COPY) {
				kdebug("share copy");
				vma->vm_flags |= VM_MAPPED_COPY;
			} else {
				kdebug("share mmap");
				ret = do_mmap_shared_file(vma);
				if (ret < 0) {
					vma->vm_region = NULL;
					vma->vm_start = 0;
					vma->vm_end = 0;
1292
					pregion->vm_usage--;
1293 1294 1295 1296 1297 1298 1299 1300 1301
					pregion = NULL;
					goto error_just_free;
				}
			}
			fput(region->vm_file);
			kmem_cache_free(vm_region_jar, region);
			region = pregion;
			result = start;
			goto share;
L
Linus Torvalds 已提交
1302 1303 1304 1305 1306 1307
		}

		/* obtain the address at which to make a shared mapping
		 * - this is the hook for quasi-memory character devices to
		 *   tell us the location of a shared mapping
		 */
1308
		if (capabilities & BDI_CAP_MAP_DIRECT) {
L
Linus Torvalds 已提交
1309 1310 1311 1312 1313
			addr = file->f_op->get_unmapped_area(file, addr, len,
							     pgoff, flags);
			if (IS_ERR((void *) addr)) {
				ret = addr;
				if (ret != (unsigned long) -ENOSYS)
1314
					goto error_just_free;
L
Linus Torvalds 已提交
1315 1316 1317 1318 1319 1320

				/* the driver refused to tell us where to site
				 * the mapping so we'll have to attempt to copy
				 * it */
				ret = (unsigned long) -ENODEV;
				if (!(capabilities & BDI_CAP_MAP_COPY))
1321
					goto error_just_free;
L
Linus Torvalds 已提交
1322 1323

				capabilities &= ~BDI_CAP_MAP_DIRECT;
1324 1325 1326
			} else {
				vma->vm_start = region->vm_start = addr;
				vma->vm_end = region->vm_end = addr + len;
L
Linus Torvalds 已提交
1327 1328 1329 1330
			}
		}
	}

1331
	vma->vm_region = region;
L
Linus Torvalds 已提交
1332

1333 1334 1335
	/* set up the mapping
	 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
	 */
L
Linus Torvalds 已提交
1336
	if (file && vma->vm_flags & VM_SHARED)
1337
		ret = do_mmap_shared_file(vma);
L
Linus Torvalds 已提交
1338
	else
1339
		ret = do_mmap_private(vma, region, len, capabilities);
L
Linus Torvalds 已提交
1340
	if (ret < 0)
1341 1342
		goto error_just_free;
	add_nommu_region(region);
1343

1344 1345 1346 1347 1348
	/* clear anonymous mappings that don't ask for uninitialized data */
	if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
		memset((void *)region->vm_start, 0,
		       region->vm_end - region->vm_start);

L
Linus Torvalds 已提交
1349
	/* okay... we have a mapping; now we have to register it */
1350
	result = vma->vm_start;
L
Linus Torvalds 已提交
1351 1352 1353

	current->mm->total_vm += len >> PAGE_SHIFT;

1354 1355
share:
	add_vma_to_mm(current->mm, vma);
L
Linus Torvalds 已提交
1356

1357 1358 1359 1360 1361 1362
	/* we flush the region from the icache only when the first executable
	 * mapping of it is made  */
	if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
		flush_icache_range(region->vm_start, region->vm_end);
		region->vm_icache_flushed = true;
	}
L
Linus Torvalds 已提交
1363

1364
	up_write(&nommu_region_sem);
L
Linus Torvalds 已提交
1365

1366 1367
	kleave(" = %lx", result);
	return result;
L
Linus Torvalds 已提交
1368

1369 1370 1371
error_just_free:
	up_write(&nommu_region_sem);
error:
1372 1373
	if (region->vm_file)
		fput(region->vm_file);
1374
	kmem_cache_free(vm_region_jar, region);
1375 1376
	if (vma->vm_file)
		fput(vma->vm_file);
1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387
	if (vma->vm_flags & VM_EXECUTABLE)
		removed_exe_file_vma(vma->vm_mm);
	kmem_cache_free(vm_area_cachep, vma);
	kleave(" = %d", ret);
	return ret;

sharing_violation:
	up_write(&nommu_region_sem);
	printk(KERN_WARNING "Attempt to share mismatched mappings\n");
	ret = -EINVAL;
	goto error;
L
Linus Torvalds 已提交
1388

1389 1390 1391 1392
error_getting_vma:
	kmem_cache_free(vm_region_jar, region);
	printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
	       " from process %d failed\n",
L
Linus Torvalds 已提交
1393 1394 1395 1396
	       len, current->pid);
	show_free_areas();
	return -ENOMEM;

1397 1398 1399
error_getting_region:
	printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
	       " from process %d failed\n",
L
Linus Torvalds 已提交
1400 1401 1402 1403
	       len, current->pid);
	show_free_areas();
	return -ENOMEM;
}
1404
EXPORT_SYMBOL(do_mmap_pgoff);
L
Linus Torvalds 已提交
1405

H
Hugh Dickins 已提交
1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430
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)) {
		file = fget(fd);
		if (!file)
			goto out;
	}

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

	down_write(&current->mm->mmap_sem);
	retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
	up_write(&current->mm->mmap_sem);

	if (file)
		fput(file);
out:
	return retval;
}

L
Linus Torvalds 已提交
1431
/*
1432 1433
 * split a vma into two pieces at address 'addr', a new vma is allocated either
 * for the first part or the tail.
L
Linus Torvalds 已提交
1434
 */
1435 1436
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
	      unsigned long addr, int new_below)
L
Linus Torvalds 已提交
1437
{
1438 1439 1440
	struct vm_area_struct *new;
	struct vm_region *region;
	unsigned long npages;
L
Linus Torvalds 已提交
1441

1442
	kenter("");
L
Linus Torvalds 已提交
1443

1444 1445 1446
	/* we're only permitted to split anonymous regions that have a single
	 * owner */
	if (vma->vm_file ||
1447
	    vma->vm_region->vm_usage != 1)
1448
		return -ENOMEM;
L
Linus Torvalds 已提交
1449

1450 1451
	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;
L
Linus Torvalds 已提交
1452

1453 1454 1455
	region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
	if (!region)
		return -ENOMEM;
L
Linus Torvalds 已提交
1456

1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470
	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
	if (!new) {
		kmem_cache_free(vm_region_jar, region);
		return -ENOMEM;
	}

	/* most fields are the same, copy all, and then fixup */
	*new = *vma;
	*region = *vma->vm_region;
	new->vm_region = region;

	npages = (addr - vma->vm_start) >> PAGE_SHIFT;

	if (new_below) {
1471
		region->vm_top = region->vm_end = new->vm_end = addr;
1472 1473 1474
	} else {
		region->vm_start = new->vm_start = addr;
		region->vm_pgoff = new->vm_pgoff += npages;
L
Linus Torvalds 已提交
1475
	}
1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487

	if (new->vm_ops && new->vm_ops->open)
		new->vm_ops->open(new);

	delete_vma_from_mm(vma);
	down_write(&nommu_region_sem);
	delete_nommu_region(vma->vm_region);
	if (new_below) {
		vma->vm_region->vm_start = vma->vm_start = addr;
		vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
	} else {
		vma->vm_region->vm_end = vma->vm_end = addr;
1488
		vma->vm_region->vm_top = addr;
1489 1490 1491 1492 1493 1494 1495
	}
	add_nommu_region(vma->vm_region);
	add_nommu_region(new->vm_region);
	up_write(&nommu_region_sem);
	add_vma_to_mm(mm, vma);
	add_vma_to_mm(mm, new);
	return 0;
L
Linus Torvalds 已提交
1496 1497
}

1498
/*
1499 1500
 * shrink a VMA by removing the specified chunk from either the beginning or
 * the end
1501
 */
1502 1503 1504
static int shrink_vma(struct mm_struct *mm,
		      struct vm_area_struct *vma,
		      unsigned long from, unsigned long to)
L
Linus Torvalds 已提交
1505
{
1506
	struct vm_region *region;
L
Linus Torvalds 已提交
1507

1508
	kenter("");
L
Linus Torvalds 已提交
1509

1510 1511 1512 1513 1514 1515 1516 1517
	/* adjust the VMA's pointers, which may reposition it in the MM's tree
	 * and list */
	delete_vma_from_mm(vma);
	if (from > vma->vm_start)
		vma->vm_end = from;
	else
		vma->vm_start = to;
	add_vma_to_mm(mm, vma);
L
Linus Torvalds 已提交
1518

1519 1520
	/* cut the backing region down to size */
	region = vma->vm_region;
1521
	BUG_ON(region->vm_usage != 1);
1522 1523 1524

	down_write(&nommu_region_sem);
	delete_nommu_region(region);
1525 1526 1527 1528
	if (from > region->vm_start) {
		to = region->vm_top;
		region->vm_top = region->vm_end = from;
	} else {
1529
		region->vm_start = to;
1530
	}
1531 1532 1533 1534 1535 1536
	add_nommu_region(region);
	up_write(&nommu_region_sem);

	free_page_series(from, to);
	return 0;
}
L
Linus Torvalds 已提交
1537

1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548
/*
 * release a mapping
 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
 *   VMA, though it need not cover the whole VMA
 */
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
	struct vm_area_struct *vma;
	struct rb_node *rb;
	unsigned long end = start + len;
	int ret;
L
Linus Torvalds 已提交
1549

1550
	kenter(",%lx,%zx", start, len);
L
Linus Torvalds 已提交
1551

1552 1553
	if (len == 0)
		return -EINVAL;
1554

1555 1556 1557
	/* find the first potentially overlapping VMA */
	vma = find_vma(mm, start);
	if (!vma) {
1558 1559 1560 1561 1562 1563 1564 1565 1566
		static int limit = 0;
		if (limit < 5) {
			printk(KERN_WARNING
			       "munmap of memory not mmapped by process %d"
			       " (%s): 0x%lx-0x%lx\n",
			       current->pid, current->comm,
			       start, start + len - 1);
			limit++;
		}
1567 1568
		return -EINVAL;
	}
L
Linus Torvalds 已提交
1569

1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608
	/* we're allowed to split an anonymous VMA but not a file-backed one */
	if (vma->vm_file) {
		do {
			if (start > vma->vm_start) {
				kleave(" = -EINVAL [miss]");
				return -EINVAL;
			}
			if (end == vma->vm_end)
				goto erase_whole_vma;
			rb = rb_next(&vma->vm_rb);
			vma = rb_entry(rb, struct vm_area_struct, vm_rb);
		} while (rb);
		kleave(" = -EINVAL [split file]");
		return -EINVAL;
	} else {
		/* the chunk must be a subset of the VMA found */
		if (start == vma->vm_start && end == vma->vm_end)
			goto erase_whole_vma;
		if (start < vma->vm_start || end > vma->vm_end) {
			kleave(" = -EINVAL [superset]");
			return -EINVAL;
		}
		if (start & ~PAGE_MASK) {
			kleave(" = -EINVAL [unaligned start]");
			return -EINVAL;
		}
		if (end != vma->vm_end && end & ~PAGE_MASK) {
			kleave(" = -EINVAL [unaligned split]");
			return -EINVAL;
		}
		if (start != vma->vm_start && end != vma->vm_end) {
			ret = split_vma(mm, vma, start, 1);
			if (ret < 0) {
				kleave(" = %d [split]", ret);
				return ret;
			}
		}
		return shrink_vma(mm, vma, start, end);
	}
L
Linus Torvalds 已提交
1609

1610 1611 1612 1613
erase_whole_vma:
	delete_vma_from_mm(vma);
	delete_vma(mm, vma);
	kleave(" = 0");
L
Linus Torvalds 已提交
1614 1615
	return 0;
}
1616
EXPORT_SYMBOL(do_munmap);
L
Linus Torvalds 已提交
1617

1618
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629
{
	int ret;
	struct mm_struct *mm = current->mm;

	down_write(&mm->mmap_sem);
	ret = do_munmap(mm, addr, len);
	up_write(&mm->mmap_sem);
	return ret;
}

/*
1630
 * release all the mappings made in a process's VM space
1631
 */
1632
void exit_mmap(struct mm_struct *mm)
L
Linus Torvalds 已提交
1633
{
1634
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1635

1636 1637
	if (!mm)
		return;
L
Linus Torvalds 已提交
1638

1639
	kenter("");
L
Linus Torvalds 已提交
1640

1641
	mm->total_vm = 0;
L
Linus Torvalds 已提交
1642

1643 1644 1645 1646
	while ((vma = mm->mmap)) {
		mm->mmap = vma->vm_next;
		delete_vma_from_mm(vma);
		delete_vma(mm, vma);
L
Linus Torvalds 已提交
1647
	}
1648 1649

	kleave("");
L
Linus Torvalds 已提交
1650 1651 1652 1653 1654 1655 1656 1657
}

unsigned long do_brk(unsigned long addr, unsigned long len)
{
	return -ENOMEM;
}

/*
1658 1659
 * expand (or shrink) an existing mapping, potentially moving it at the same
 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
L
Linus Torvalds 已提交
1660
 *
1661
 * under NOMMU conditions, we only permit changing a mapping's size, and only
1662 1663
 * as long as it stays within the region allocated by do_mmap_private() and the
 * block is not shareable
L
Linus Torvalds 已提交
1664
 *
1665
 * MREMAP_FIXED is not supported under NOMMU conditions
L
Linus Torvalds 已提交
1666 1667 1668 1669 1670
 */
unsigned long do_mremap(unsigned long addr,
			unsigned long old_len, unsigned long new_len,
			unsigned long flags, unsigned long new_addr)
{
1671
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1672 1673

	/* insanity checks first */
1674
	if (old_len == 0 || new_len == 0)
L
Linus Torvalds 已提交
1675 1676
		return (unsigned long) -EINVAL;

1677 1678 1679
	if (addr & ~PAGE_MASK)
		return -EINVAL;

L
Linus Torvalds 已提交
1680 1681 1682
	if (flags & MREMAP_FIXED && new_addr != addr)
		return (unsigned long) -EINVAL;

1683
	vma = find_vma_exact(current->mm, addr, old_len);
1684 1685
	if (!vma)
		return (unsigned long) -EINVAL;
L
Linus Torvalds 已提交
1686

1687
	if (vma->vm_end != vma->vm_start + old_len)
L
Linus Torvalds 已提交
1688 1689
		return (unsigned long) -EFAULT;

1690
	if (vma->vm_flags & VM_MAYSHARE)
L
Linus Torvalds 已提交
1691 1692
		return (unsigned long) -EPERM;

1693
	if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
L
Linus Torvalds 已提交
1694 1695 1696
		return (unsigned long) -ENOMEM;

	/* all checks complete - do it */
1697 1698 1699
	vma->vm_end = vma->vm_start + new_len;
	return vma->vm_start;
}
1700
EXPORT_SYMBOL(do_mremap);
1701

1702 1703 1704
SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
		unsigned long, new_len, unsigned long, flags,
		unsigned long, new_addr)
1705 1706 1707 1708 1709 1710 1711
{
	unsigned long ret;

	down_write(&current->mm->mmap_sem);
	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
	up_write(&current->mm->mmap_sem);
	return ret;
L
Linus Torvalds 已提交
1712 1713
}

1714
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1715
			unsigned int foll_flags)
L
Linus Torvalds 已提交
1716 1717 1718 1719 1720 1721 1722
{
	return NULL;
}

int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
		unsigned long to, unsigned long size, pgprot_t prot)
{
1723 1724
	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
	return 0;
L
Linus Torvalds 已提交
1725
}
1726
EXPORT_SYMBOL(remap_pfn_range);
L
Linus Torvalds 已提交
1727

1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742
int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
			unsigned long pgoff)
{
	unsigned int size = vma->vm_end - vma->vm_start;

	if (!(vma->vm_flags & VM_USERMAP))
		return -EINVAL;

	vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
	vma->vm_end = vma->vm_start + size;

	return 0;
}
EXPORT_SYMBOL(remap_vmalloc_range);

L
Linus Torvalds 已提交
1743 1744 1745 1746 1747 1748 1749 1750 1751 1752
void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
{
}

unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
	unsigned long len, unsigned long pgoff, unsigned long flags)
{
	return -ENOMEM;
}

1753
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1754 1755 1756 1757 1758 1759 1760 1761
{
}

void unmap_mapping_range(struct address_space *mapping,
			 loff_t const holebegin, loff_t const holelen,
			 int even_cows)
{
}
1762
EXPORT_SYMBOL(unmap_mapping_range);
L
Linus Torvalds 已提交
1763

1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784
/*
 * ask for an unmapped area at which to create a mapping on a file
 */
unsigned long get_unmapped_area(struct file *file, unsigned long addr,
				unsigned long len, unsigned long pgoff,
				unsigned long flags)
{
	unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
				  unsigned long, unsigned long);

	get_area = current->mm->get_unmapped_area;
	if (file && file->f_op && file->f_op->get_unmapped_area)
		get_area = file->f_op->get_unmapped_area;

	if (!get_area)
		return -ENOSYS;

	return get_area(file, addr, len, pgoff, flags);
}
EXPORT_SYMBOL(get_unmapped_area);

L
Linus Torvalds 已提交
1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800
/*
 * 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.
 */
1801
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
L
Linus Torvalds 已提交
1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815
{
	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) {
		unsigned long n;

1816
		free = global_page_state(NR_FILE_PAGES);
L
Linus Torvalds 已提交
1817 1818 1819 1820 1821 1822 1823 1824
		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
		 */
1825
		free += global_page_state(NR_SLAB_RECLAIMABLE);
L
Linus Torvalds 已提交
1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840

		/*
		 * Leave the last 3% for root
		 */
		if (!cap_sys_admin)
			free -= free / 32;

		if (free > pages)
			return 0;

		/*
		 * nr_free_pages() is very expensive on large systems,
		 * only call if we're about to fail.
		 */
		n = nr_free_pages();
1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852

		/*
		 * Leave reserved pages. The pages are not for anonymous pages.
		 */
		if (n <= totalreserve_pages)
			goto error;
		else
			n -= totalreserve_pages;

		/*
		 * Leave the last 3% for root
		 */
L
Linus Torvalds 已提交
1853 1854 1855 1856 1857 1858
		if (!cap_sys_admin)
			n -= n / 32;
		free += n;

		if (free > pages)
			return 0;
1859 1860

		goto error;
L
Linus Torvalds 已提交
1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872
	}

	allowed = totalram_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 */
A
Alan Cox 已提交
1873 1874
	if (mm)
		allowed -= mm->total_vm / 32;
L
Linus Torvalds 已提交
1875

1876
	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
L
Linus Torvalds 已提交
1877
		return 0;
1878

1879
error:
L
Linus Torvalds 已提交
1880 1881 1882 1883 1884 1885 1886 1887 1888
	vm_unacct_memory(pages);

	return -ENOMEM;
}

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}
1889

N
Nick Piggin 已提交
1890
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1891 1892
{
	BUG();
N
Nick Piggin 已提交
1893
	return 0;
1894
}
1895
EXPORT_SYMBOL(filemap_fault);
1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915

/*
 * Access another process' address space.
 * - source/target buffer must be kernel space
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct vm_area_struct *vma;
	struct mm_struct *mm;

	if (addr + len < addr)
		return 0;

	mm = get_task_mm(tsk);
	if (!mm)
		return 0;

	down_read(&mm->mmap_sem);

	/* the access must start within one of the target process's mappings */
1916 1917
	vma = find_vma(mm, addr);
	if (vma) {
1918 1919 1920 1921 1922
		/* don't overrun this mapping */
		if (addr + len >= vma->vm_end)
			len = vma->vm_end - addr;

		/* only read or write mappings where it is permitted */
1923
		if (write && vma->vm_flags & VM_MAYWRITE)
1924 1925
			copy_to_user_page(vma, NULL, addr,
					 (void *) addr, buf, len);
1926
		else if (!write && vma->vm_flags & VM_MAYREAD)
1927 1928
			copy_from_user_page(vma, NULL, addr,
					    buf, (void *) addr, len);
1929 1930 1931 1932 1933 1934 1935 1936 1937 1938
		else
			len = 0;
	} else {
		len = 0;
	}

	up_read(&mm->mmap_sem);
	mmput(mm);
	return len;
}