memory.c 78.1 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

/*
 * demand-loading started 01.12.91 - seems it is high on the list of
 * things wanted, and it should be easy to implement. - Linus
 */

/*
 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
 * pages started 02.12.91, seems to work. - Linus.
 *
 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
 * would have taken more than the 6M I have free, but it worked well as
 * far as I could see.
 *
 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
 */

/*
 * Real VM (paging to/from disk) started 18.12.91. Much more work and
 * thought has to go into this. Oh, well..
 * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
 *		Found it. Everything seems to work now.
 * 20.12.91  -  Ok, making the swap-device changeable like the root.
 */

/*
 * 05.04.94  -  Multi-page memory management added for v1.1.
 * 		Idea by Alex Bligh (alex@cconcepts.co.uk)
 *
 * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
 *		(Gerhard.Wichert@pdb.siemens.de)
 *
 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
 */

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include <linux/module.h>
50
#include <linux/delayacct.h>
L
Linus Torvalds 已提交
51
#include <linux/init.h>
P
Peter Zijlstra 已提交
52
#include <linux/writeback.h>
53
#include <linux/memcontrol.h>
L
Linus Torvalds 已提交
54 55 56 57 58 59 60 61 62 63

#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>

#include <linux/swapops.h>
#include <linux/elf.h>

A
Andy Whitcroft 已提交
64
#ifndef CONFIG_NEED_MULTIPLE_NODES
L
Linus Torvalds 已提交
65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85
/* use the per-pgdat data instead for discontigmem - mbligh */
unsigned long max_mapnr;
struct page *mem_map;

EXPORT_SYMBOL(max_mapnr);
EXPORT_SYMBOL(mem_map);
#endif

unsigned long num_physpages;
/*
 * A number of key systems in x86 including ioremap() rely on the assumption
 * that high_memory defines the upper bound on direct map memory, then end
 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
 * and ZONE_HIGHMEM.
 */
void * high_memory;

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);

86 87 88 89 90 91 92 93 94 95 96 97
/*
 * Randomize the address space (stacks, mmaps, brk, etc.).
 *
 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
 *   as ancient (libc5 based) binaries can segfault. )
 */
int randomize_va_space __read_mostly =
#ifdef CONFIG_COMPAT_BRK
					1;
#else
					2;
#endif
98 99 100 101

static int __init disable_randmaps(char *s)
{
	randomize_va_space = 0;
102
	return 1;
103 104 105 106
}
__setup("norandmaps", disable_randmaps);


L
Linus Torvalds 已提交
107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134
/*
 * If a p?d_bad entry is found while walking page tables, report
 * the error, before resetting entry to p?d_none.  Usually (but
 * very seldom) called out from the p?d_none_or_clear_bad macros.
 */

void pgd_clear_bad(pgd_t *pgd)
{
	pgd_ERROR(*pgd);
	pgd_clear(pgd);
}

void pud_clear_bad(pud_t *pud)
{
	pud_ERROR(*pud);
	pud_clear(pud);
}

void pmd_clear_bad(pmd_t *pmd)
{
	pmd_ERROR(*pmd);
	pmd_clear(pmd);
}

/*
 * Note: this doesn't free the actual pages themselves. That
 * has been handled earlier when unmapping all the memory regions.
 */
135
static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
L
Linus Torvalds 已提交
136
{
137
	pgtable_t token = pmd_pgtable(*pmd);
138
	pmd_clear(pmd);
139
	pte_free_tlb(tlb, token);
140
	tlb->mm->nr_ptes--;
L
Linus Torvalds 已提交
141 142
}

143 144 145
static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
L
Linus Torvalds 已提交
146 147 148
{
	pmd_t *pmd;
	unsigned long next;
149
	unsigned long start;
L
Linus Torvalds 已提交
150

151
	start = addr;
L
Linus Torvalds 已提交
152 153 154 155 156
	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			continue;
157
		free_pte_range(tlb, pmd);
L
Linus Torvalds 已提交
158 159
	} while (pmd++, addr = next, addr != end);

160 161 162 163 164 165 166
	start &= PUD_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
L
Linus Torvalds 已提交
167
	}
168 169 170 171 172 173
	if (end - 1 > ceiling - 1)
		return;

	pmd = pmd_offset(pud, start);
	pud_clear(pud);
	pmd_free_tlb(tlb, pmd);
L
Linus Torvalds 已提交
174 175
}

176 177 178
static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
L
Linus Torvalds 已提交
179 180 181
{
	pud_t *pud;
	unsigned long next;
182
	unsigned long start;
L
Linus Torvalds 已提交
183

184
	start = addr;
L
Linus Torvalds 已提交
185 186 187 188 189
	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
190
		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
L
Linus Torvalds 已提交
191 192
	} while (pud++, addr = next, addr != end);

193 194 195 196 197 198 199
	start &= PGDIR_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
L
Linus Torvalds 已提交
200
	}
201 202 203 204 205 206
	if (end - 1 > ceiling - 1)
		return;

	pud = pud_offset(pgd, start);
	pgd_clear(pgd);
	pud_free_tlb(tlb, pud);
L
Linus Torvalds 已提交
207 208 209
}

/*
210 211
 * This function frees user-level page tables of a process.
 *
L
Linus Torvalds 已提交
212 213
 * Must be called with pagetable lock held.
 */
214
void free_pgd_range(struct mmu_gather **tlb,
215 216
			unsigned long addr, unsigned long end,
			unsigned long floor, unsigned long ceiling)
L
Linus Torvalds 已提交
217 218 219
{
	pgd_t *pgd;
	unsigned long next;
220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246
	unsigned long start;

	/*
	 * The next few lines have given us lots of grief...
	 *
	 * Why are we testing PMD* at this top level?  Because often
	 * there will be no work to do at all, and we'd prefer not to
	 * go all the way down to the bottom just to discover that.
	 *
	 * Why all these "- 1"s?  Because 0 represents both the bottom
	 * of the address space and the top of it (using -1 for the
	 * top wouldn't help much: the masks would do the wrong thing).
	 * The rule is that addr 0 and floor 0 refer to the bottom of
	 * the address space, but end 0 and ceiling 0 refer to the top
	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
	 * that end 0 case should be mythical).
	 *
	 * Wherever addr is brought up or ceiling brought down, we must
	 * be careful to reject "the opposite 0" before it confuses the
	 * subsequent tests.  But what about where end is brought down
	 * by PMD_SIZE below? no, end can't go down to 0 there.
	 *
	 * Whereas we round start (addr) and ceiling down, by different
	 * masks at different levels, in order to test whether a table
	 * now has no other vmas using it, so can be freed, we don't
	 * bother to round floor or end up - the tests don't need that.
	 */
L
Linus Torvalds 已提交
247

248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264
	addr &= PMD_MASK;
	if (addr < floor) {
		addr += PMD_SIZE;
		if (!addr)
			return;
	}
	if (ceiling) {
		ceiling &= PMD_MASK;
		if (!ceiling)
			return;
	}
	if (end - 1 > ceiling - 1)
		end -= PMD_SIZE;
	if (addr > end - 1)
		return;

	start = addr;
265
	pgd = pgd_offset((*tlb)->mm, addr);
L
Linus Torvalds 已提交
266 267 268 269
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
270
		free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
L
Linus Torvalds 已提交
271
	} while (pgd++, addr = next, addr != end);
272 273 274
}

void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
275
		unsigned long floor, unsigned long ceiling)
276 277 278 279 280
{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

281 282 283 284 285 286
		/*
		 * Hide vma from rmap and vmtruncate before freeing pgtables
		 */
		anon_vma_unlink(vma);
		unlink_file_vma(vma);

287
		if (is_vm_hugetlb_page(vma)) {
288
			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
289
				floor, next? next->vm_start: ceiling);
290 291 292 293 294
		} else {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
295
			       && !is_vm_hugetlb_page(next)) {
296 297
				vma = next;
				next = vma->vm_next;
298 299
				anon_vma_unlink(vma);
				unlink_file_vma(vma);
300 301 302 303
			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
304 305
		vma = next;
	}
L
Linus Torvalds 已提交
306 307
}

308
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
309
{
310
	pgtable_t new = pte_alloc_one(mm, address);
311 312 313
	if (!new)
		return -ENOMEM;

314 315 316 317 318 319 320 321 322 323 324 325 326 327 328
	/*
	 * Ensure all pte setup (eg. pte page lock and page clearing) are
	 * visible before the pte is made visible to other CPUs by being
	 * put into page tables.
	 *
	 * The other side of the story is the pointer chasing in the page
	 * table walking code (when walking the page table without locking;
	 * ie. most of the time). Fortunately, these data accesses consist
	 * of a chain of data-dependent loads, meaning most CPUs (alpha
	 * being the notable exception) will already guarantee loads are
	 * seen in-order. See the alpha page table accessors for the
	 * smp_read_barrier_depends() barriers in page table walking code.
	 */
	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */

H
Hugh Dickins 已提交
329
	spin_lock(&mm->page_table_lock);
330
	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
L
Linus Torvalds 已提交
331 332
		mm->nr_ptes++;
		pmd_populate(mm, pmd, new);
333
		new = NULL;
L
Linus Torvalds 已提交
334
	}
H
Hugh Dickins 已提交
335
	spin_unlock(&mm->page_table_lock);
336 337
	if (new)
		pte_free(mm, new);
338
	return 0;
L
Linus Torvalds 已提交
339 340
}

341
int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
342
{
343 344 345 346
	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
	if (!new)
		return -ENOMEM;

347 348
	smp_wmb(); /* See comment in __pte_alloc */

349
	spin_lock(&init_mm.page_table_lock);
350
	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
351
		pmd_populate_kernel(&init_mm, pmd, new);
352 353
		new = NULL;
	}
354
	spin_unlock(&init_mm.page_table_lock);
355 356
	if (new)
		pte_free_kernel(&init_mm, new);
357
	return 0;
L
Linus Torvalds 已提交
358 359
}

360 361 362 363 364 365 366 367
static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
{
	if (file_rss)
		add_mm_counter(mm, file_rss, file_rss);
	if (anon_rss)
		add_mm_counter(mm, anon_rss, anon_rss);
}

N
Nick Piggin 已提交
368
/*
369 370 371
 * This function is called to print an error when a bad pte
 * is found. For example, we might have a PFN-mapped pte in
 * a region that doesn't allow it.
N
Nick Piggin 已提交
372 373 374 375 376 377 378 379 380 381 382 383 384
 *
 * The calling function must still handle the error.
 */
void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
{
	printk(KERN_ERR "Bad pte = %08llx, process = %s, "
			"vm_flags = %lx, vaddr = %lx\n",
		(long long)pte_val(pte),
		(vma->vm_mm == current->mm ? current->comm : "???"),
		vma->vm_flags, vaddr);
	dump_stack();
}

385 386 387 388 389
static inline int is_cow_mapping(unsigned int flags)
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

H
Hugh Dickins 已提交
390
/*
N
Nick Piggin 已提交
391
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
392
 *
N
Nick Piggin 已提交
393 394 395
 * "Special" mappings do not wish to be associated with a "struct page" (either
 * it doesn't exist, or it exists but they don't want to touch it). In this
 * case, NULL is returned here. "Normal" mappings do have a struct page.
J
Jared Hulbert 已提交
396
 *
N
Nick Piggin 已提交
397 398 399 400 401 402 403 404
 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 * pte bit, in which case this function is trivial. Secondly, an architecture
 * may not have a spare pte bit, which requires a more complicated scheme,
 * described below.
 *
 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 * special mapping (even if there are underlying and valid "struct pages").
 * COWed pages of a VM_PFNMAP are always normal.
405
 *
J
Jared Hulbert 已提交
406 407
 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
N
Nick Piggin 已提交
408 409
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
410 411 412
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
413 414 415 416 417 418
 * And for normal mappings this is false.
 *
 * This restricts such mappings to be a linear translation from virtual address
 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 * as the vma is not a COW mapping; in that case, we know that all ptes are
 * special (because none can have been COWed).
J
Jared Hulbert 已提交
419 420
 *
 *
N
Nick Piggin 已提交
421
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
422 423 424 425 426 427 428 429 430
 *
 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 * page" backing, however the difference is that _all_ pages with a struct
 * page (that is, those where pfn_valid is true) are refcounted and considered
 * normal pages by the VM. The disadvantage is that pages are refcounted
 * (which can be slower and simply not an option for some PFNMAP users). The
 * advantage is that we don't have to follow the strict linearity rule of
 * PFNMAP mappings in order to support COWable mappings.
 *
H
Hugh Dickins 已提交
431
 */
N
Nick Piggin 已提交
432 433 434 435 436 437 438
#ifdef __HAVE_ARCH_PTE_SPECIAL
# define HAVE_PTE_SPECIAL 1
#else
# define HAVE_PTE_SPECIAL 0
#endif
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
				pte_t pte)
H
Hugh Dickins 已提交
439
{
N
Nick Piggin 已提交
440 441 442 443 444 445 446 447 448 449 450 451 452 453
	unsigned long pfn;

	if (HAVE_PTE_SPECIAL) {
		if (likely(!pte_special(pte))) {
			VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
			return pte_page(pte);
		}
		VM_BUG_ON(!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)));
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

	pfn = pte_pfn(pte);
454

J
Jared Hulbert 已提交
455 456 457 458 459 460
	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
N
Nick Piggin 已提交
461 462
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
463 464 465 466 467
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
468 469
	}

N
Nick Piggin 已提交
470
	VM_BUG_ON(!pfn_valid(pfn));
471 472

	/*
N
Nick Piggin 已提交
473
	 * NOTE! We still have PageReserved() pages in the page tables.
474
	 *
N
Nick Piggin 已提交
475
	 * eg. VDSO mappings can cause them to exist.
476
	 */
J
Jared Hulbert 已提交
477
out:
478
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
479 480
}

L
Linus Torvalds 已提交
481 482 483 484 485 486
/*
 * copy one vm_area from one task to the other. Assumes the page tables
 * already present in the new task to be cleared in the whole range
 * covered by this vma.
 */

H
Hugh Dickins 已提交
487
static inline void
L
Linus Torvalds 已提交
488
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
489
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
490
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
491
{
N
Nick Piggin 已提交
492
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
493 494 495 496 497 498
	pte_t pte = *src_pte;
	struct page *page;

	/* pte contains position in swap or file, so copy. */
	if (unlikely(!pte_present(pte))) {
		if (!pte_file(pte)) {
499 500 501
			swp_entry_t entry = pte_to_swp_entry(pte);

			swap_duplicate(entry);
L
Linus Torvalds 已提交
502 503 504
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
505 506 507
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
508 509
				spin_unlock(&mmlist_lock);
			}
510 511 512 513 514 515 516 517 518 519
			if (is_write_migration_entry(entry) &&
					is_cow_mapping(vm_flags)) {
				/*
				 * COW mappings require pages in both parent
				 * and child to be set to read.
				 */
				make_migration_entry_read(&entry);
				pte = swp_entry_to_pte(entry);
				set_pte_at(src_mm, addr, src_pte, pte);
			}
L
Linus Torvalds 已提交
520
		}
521
		goto out_set_pte;
L
Linus Torvalds 已提交
522 523 524 525 526 527
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
528
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
529
		ptep_set_wrprotect(src_mm, addr, src_pte);
530
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
531 532 533 534 535 536 537 538 539
	}

	/*
	 * If it's a shared mapping, mark it clean in
	 * the child
	 */
	if (vm_flags & VM_SHARED)
		pte = pte_mkclean(pte);
	pte = pte_mkold(pte);
540 541 542 543

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
N
Nick Piggin 已提交
544
		page_dup_rmap(page, vma, addr);
545 546
		rss[!!PageAnon(page)]++;
	}
547 548 549

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
L
Linus Torvalds 已提交
550 551 552 553 554 555 556
}

static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
557
	spinlock_t *src_ptl, *dst_ptl;
558
	int progress = 0;
H
Hugh Dickins 已提交
559
	int rss[2];
L
Linus Torvalds 已提交
560 561

again:
562
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
563
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
564 565 566
	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
567
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
568
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
569
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
570 571 572 573 574 575

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
576 577 578
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
579
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
580 581
				break;
		}
L
Linus Torvalds 已提交
582 583 584 585
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
586
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
587 588 589
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

590
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
591
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
592
	pte_unmap_nested(src_pte - 1);
593
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
594 595
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
L
Linus Torvalds 已提交
596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652
	if (addr != end)
		goto again;
	return 0;
}

static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pmd_t *src_pmd, *dst_pmd;
	unsigned long next;

	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
	if (!dst_pmd)
		return -ENOMEM;
	src_pmd = pmd_offset(src_pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(src_pmd))
			continue;
		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
	return 0;
}

static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pud_t *src_pud, *dst_pud;
	unsigned long next;

	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
	if (!dst_pud)
		return -ENOMEM;
	src_pud = pud_offset(src_pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(src_pud))
			continue;
		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pud++, src_pud++, addr = next, addr != end);
	return 0;
}

int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		struct vm_area_struct *vma)
{
	pgd_t *src_pgd, *dst_pgd;
	unsigned long next;
	unsigned long addr = vma->vm_start;
	unsigned long end = vma->vm_end;

653 654 655 656 657 658
	/*
	 * Don't copy ptes where a page fault will fill them correctly.
	 * Fork becomes much lighter when there are big shared or private
	 * readonly mappings. The tradeoff is that copy_page_range is more
	 * efficient than faulting.
	 */
659
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
660 661 662 663
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

	dst_pgd = pgd_offset(dst_mm, addr);
	src_pgd = pgd_offset(src_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(src_pgd))
			continue;
		if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
	return 0;
}

680
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
681
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
682
				unsigned long addr, unsigned long end,
683
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
684
{
N
Nick Piggin 已提交
685
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
686
	pte_t *pte;
687
	spinlock_t *ptl;
688 689
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
690

691
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
692
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
693 694
	do {
		pte_t ptent = *pte;
695 696
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
697
			continue;
698
		}
699 700 701

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
702
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
703
			struct page *page;
704

705
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
				/*
				 * Each page->index must be checked when
				 * invalidating or truncating nonlinear.
				 */
				if (details->nonlinear_vma &&
				    (page->index < details->first_index ||
				     page->index > details->last_index))
					continue;
			}
N
Nick Piggin 已提交
724
			ptent = ptep_get_and_clear_full(mm, addr, pte,
725
							tlb->fullmm);
L
Linus Torvalds 已提交
726 727 728 729 730 731
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (unlikely(details) && details->nonlinear_vma
			    && linear_page_index(details->nonlinear_vma,
						addr) != page->index)
N
Nick Piggin 已提交
732
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
733 734
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
735
				anon_rss--;
736 737 738 739
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
740
					SetPageReferenced(page);
H
Hugh Dickins 已提交
741
				file_rss--;
742
			}
N
Nick Piggin 已提交
743
			page_remove_rmap(page, vma);
L
Linus Torvalds 已提交
744 745 746 747 748 749 750 751 752 753 754
			tlb_remove_page(tlb, page);
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
		if (!pte_file(ptent))
			free_swap_and_cache(pte_to_swp_entry(ptent));
755
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
756
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
757

H
Hugh Dickins 已提交
758
	add_mm_rss(mm, file_rss, anon_rss);
759
	arch_leave_lazy_mmu_mode();
760
	pte_unmap_unlock(pte - 1, ptl);
761 762

	return addr;
L
Linus Torvalds 已提交
763 764
}

765
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
766
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
767
				unsigned long addr, unsigned long end,
768
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
769 770 771 772 773 774 775
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
776 777
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
778
			continue;
779 780 781 782 783 784
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
785 786
}

787
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
788
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
789
				unsigned long addr, unsigned long end,
790
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
791 792 793 794 795 796 797
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
798 799
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
800
			continue;
801 802 803 804 805 806
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
807 808
}

809 810
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
811
				unsigned long addr, unsigned long end,
812
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
813 814 815 816 817 818 819 820 821 822 823 824
{
	pgd_t *pgd;
	unsigned long next;

	if (details && !details->check_mapping && !details->nonlinear_vma)
		details = NULL;

	BUG_ON(addr >= end);
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
825 826
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
827
			continue;
828 829 830 831
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
L
Linus Torvalds 已提交
832
	tlb_end_vma(tlb, vma);
833 834

	return addr;
L
Linus Torvalds 已提交
835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852
}

#ifdef CONFIG_PREEMPT
# define ZAP_BLOCK_SIZE	(8 * PAGE_SIZE)
#else
/* No preempt: go for improved straight-line efficiency */
# define ZAP_BLOCK_SIZE	(1024 * PAGE_SIZE)
#endif

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
 * @tlbp: address of the caller's struct mmu_gather
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 * @details: details of nonlinear truncation or shared cache invalidation
 *
853
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
854
 *
855
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
856
 *
857 858
 * We aim to not hold locks for too long (for scheduling latency reasons).
 * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
L
Linus Torvalds 已提交
859 860 861 862 863 864 865 866 867 868 869
 * return the ending mmu_gather to the caller.
 *
 * Only addresses between `start' and `end' will be unmapped.
 *
 * The VMA list must be sorted in ascending virtual address order.
 *
 * unmap_vmas() assumes that the caller will flush the whole unmapped address
 * range after unmap_vmas() returns.  So the only responsibility here is to
 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 * drops the lock and schedules.
 */
870
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
871 872 873 874
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
875
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
876 877
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
878
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
879
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
880
	int fullmm = (*tlbp)->fullmm;
L
Linus Torvalds 已提交
881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900

	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
		unsigned long end;

		start = max(vma->vm_start, start_addr);
		if (start >= vma->vm_end)
			continue;
		end = min(vma->vm_end, end_addr);
		if (end <= vma->vm_start)
			continue;

		if (vma->vm_flags & VM_ACCOUNT)
			*nr_accounted += (end - start) >> PAGE_SHIFT;

		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

901
			if (unlikely(is_vm_hugetlb_page(vma))) {
L
Linus Torvalds 已提交
902
				unmap_hugepage_range(vma, start, end);
903 904 905 906 907 908 909 910 911 912
				zap_work -= (end - start) /
						(HPAGE_SIZE / PAGE_SIZE);
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

			if (zap_work > 0) {
				BUG_ON(start != end);
				break;
L
Linus Torvalds 已提交
913 914 915 916 917
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
918
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
919
				if (i_mmap_lock) {
920
					*tlbp = NULL;
L
Linus Torvalds 已提交
921 922 923 924 925
					goto out;
				}
				cond_resched();
			}

926
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
927
			tlb_start_valid = 0;
928
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
929 930 931
		}
	}
out:
932
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
933 934 935 936 937 938 939 940 941
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
 */
942
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
943 944 945 946 947 948 949 950 951
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
	struct mmu_gather *tlb;
	unsigned long end = address + size;
	unsigned long nr_accounted = 0;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
952
	update_hiwater_rss(mm);
953 954 955
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
956
	return end;
L
Linus Torvalds 已提交
957 958 959 960 961
}

/*
 * Do a quick page-table lookup for a single page.
 */
962
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
963
			unsigned int flags)
L
Linus Torvalds 已提交
964 965 966 967 968
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
969
	spinlock_t *ptl;
L
Linus Torvalds 已提交
970
	struct page *page;
971
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
972

973 974 975 976 977
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
Linus Torvalds 已提交
978

979
	page = NULL;
L
Linus Torvalds 已提交
980 981
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
982
		goto no_page_table;
L
Linus Torvalds 已提交
983 984 985

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
986
		goto no_page_table;
L
Linus Torvalds 已提交
987 988
	
	pmd = pmd_offset(pud, address);
989
	if (pmd_none(*pmd))
990 991 992 993 994
		goto no_page_table;

	if (pmd_huge(*pmd)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
995
		goto out;
996
	}
L
Linus Torvalds 已提交
997

998 999 1000
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1001
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1002 1003

	pte = *ptep;
1004
	if (!pte_present(pte))
1005
		goto no_page;
1006 1007
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
1008 1009
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
1010
		goto bad_page;
L
Linus Torvalds 已提交
1011

1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1022
out:
1023
	return page;
L
Linus Torvalds 已提交
1024

1025 1026 1027 1028 1029 1030 1031 1032 1033
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
	/* Fall through to ZERO_PAGE handling */
1034 1035 1036 1037 1038 1039
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
N
Nick Piggin 已提交
1040
		page = ZERO_PAGE(0);
1041 1042 1043 1044 1045
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1046 1047
}

1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067
/* Can we do the FOLL_ANON optimization? */
static inline int use_zero_page(struct vm_area_struct *vma)
{
	/*
	 * We don't want to optimize FOLL_ANON for make_pages_present()
	 * when it tries to page in a VM_LOCKED region. As to VM_SHARED,
	 * we want to get the page from the page tables to make sure
	 * that we serialize and update with any other user of that
	 * mapping.
	 */
	if (vma->vm_flags & (VM_LOCKED | VM_SHARED))
		return 0;
	/*
	 * And if we have a fault or a nopfn routine, it's not an
	 * anonymous region.
	 */
	return !vma->vm_ops ||
		(!vma->vm_ops->fault && !vma->vm_ops->nopfn);
}

L
Linus Torvalds 已提交
1068 1069 1070 1071 1072
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long start, int len, int write, int force,
		struct page **pages, struct vm_area_struct **vmas)
{
	int i;
1073
	unsigned int vm_flags;
L
Linus Torvalds 已提交
1074

1075 1076
	if (len <= 0)
		return 0;
L
Linus Torvalds 已提交
1077 1078 1079 1080
	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
1081 1082
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
1083 1084 1085
	i = 0;

	do {
1086 1087
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106

		vma = find_extend_vma(mm, start);
		if (!vma && in_gate_area(tsk, start)) {
			unsigned long pg = start & PAGE_MASK;
			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
			if (write) /* user gate pages are read-only */
				return i ? : -EFAULT;
			if (pg > TASK_SIZE)
				pgd = pgd_offset_k(pg);
			else
				pgd = pgd_offset_gate(mm, pg);
			BUG_ON(pgd_none(*pgd));
			pud = pud_offset(pgd, pg);
			BUG_ON(pud_none(*pud));
			pmd = pmd_offset(pud, pg);
1107 1108
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1109
			pte = pte_offset_map(pmd, pg);
1110 1111 1112 1113
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1114
			if (pages) {
1115
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1116 1117 1118
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1119 1120 1121 1122 1123 1124 1125 1126 1127 1128
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1129
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1130
				|| !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1131 1132 1133 1134
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1135
						&start, &len, i, write);
L
Linus Torvalds 已提交
1136 1137
			continue;
		}
1138 1139 1140 1141

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
1142
		if (!write && use_zero_page(vma))
1143 1144
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1145
		do {
1146
			struct page *page;
L
Linus Torvalds 已提交
1147

1148 1149 1150 1151 1152 1153 1154 1155
			/*
			 * If tsk is ooming, cut off its access to large memory
			 * allocations. It has a pending SIGKILL, but it can't
			 * be processed until returning to user space.
			 */
			if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
				return -ENOMEM;

1156 1157
			if (write)
				foll_flags |= FOLL_WRITE;
1158

1159
			cond_resched();
1160
			while (!(page = follow_page(vma, start, foll_flags))) {
1161
				int ret;
N
Nick Piggin 已提交
1162
				ret = handle_mm_fault(mm, vma, start,
1163
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
					else if (ret & VM_FAULT_SIGBUS)
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1176
				/*
N
Nick Piggin 已提交
1177 1178 1179 1180 1181
				 * The VM_FAULT_WRITE bit tells us that
				 * do_wp_page has broken COW when necessary,
				 * even if maybe_mkwrite decided not to set
				 * pte_write. We can thus safely do subsequent
				 * page lookups as if they were reads.
1182 1183
				 */
				if (ret & VM_FAULT_WRITE)
1184
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1185

1186
				cond_resched();
L
Linus Torvalds 已提交
1187
			}
1188 1189
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1190
			if (pages) {
1191
				pages[i] = page;
1192

1193
				flush_anon_page(vma, page, start);
1194
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1195 1196 1197 1198 1199 1200
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1201 1202
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1203 1204 1205 1206
	return i;
}
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1207 1208
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1209 1210 1211 1212
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1213
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1214 1215 1216 1217 1218 1219
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1220 1221 1222 1223 1224 1225 1226
/*
 * This is the old fallback for page remapping.
 *
 * For historical reasons, it only allows reserved pages. Only
 * old drivers should use this, and they needed to mark their
 * pages reserved for the old functions anyway.
 */
N
Nick Piggin 已提交
1227 1228
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1229
{
N
Nick Piggin 已提交
1230
	struct mm_struct *mm = vma->vm_mm;
1231
	int retval;
1232
	pte_t *pte;
1233 1234
	spinlock_t *ptl;

1235
	retval = mem_cgroup_charge(page, mm, GFP_KERNEL);
1236 1237
	if (retval)
		goto out;
1238 1239

	retval = -EINVAL;
1240
	if (PageAnon(page))
1241
		goto out_uncharge;
1242 1243
	retval = -ENOMEM;
	flush_dcache_page(page);
1244
	pte = get_locked_pte(mm, addr, &ptl);
1245
	if (!pte)
1246
		goto out_uncharge;
1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
	inc_mm_counter(mm, file_rss);
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1258 1259
	pte_unmap_unlock(pte, ptl);
	return retval;
1260 1261
out_unlock:
	pte_unmap_unlock(pte, ptl);
1262 1263
out_uncharge:
	mem_cgroup_uncharge_page(page);
1264 1265 1266 1267
out:
	return retval;
}

1268 1269 1270 1271 1272 1273
/**
 * vm_insert_page - insert single page into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @page: source kernel page
 *
1274 1275 1276 1277 1278 1279
 * This allows drivers to insert individual pages they've allocated
 * into a user vma.
 *
 * The page has to be a nice clean _individual_ kernel allocation.
 * If you allocate a compound page, you need to have marked it as
 * such (__GFP_COMP), or manually just split the page up yourself
N
Nick Piggin 已提交
1280
 * (see split_page()).
1281 1282 1283 1284 1285 1286 1287 1288 1289
 *
 * NOTE! Traditionally this was done with "remap_pfn_range()" which
 * took an arbitrary page protection parameter. This doesn't allow
 * that. Your vma protection will have to be set up correctly, which
 * means that if you want a shared writable mapping, you'd better
 * ask for a shared writable mapping!
 *
 * The page does not need to be reserved.
 */
N
Nick Piggin 已提交
1290 1291
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1292 1293 1294 1295 1296
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1297
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1298
	return insert_page(vma, addr, page, vma->vm_page_prot);
1299
}
1300
EXPORT_SYMBOL(vm_insert_page);
1301

N
Nick Piggin 已提交
1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn, pgprot_t prot)
{
	struct mm_struct *mm = vma->vm_mm;
	int retval;
	pte_t *pte, entry;
	spinlock_t *ptl;

	retval = -ENOMEM;
	pte = get_locked_pte(mm, addr, &ptl);
	if (!pte)
		goto out;
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	entry = pte_mkspecial(pfn_pte(pfn, prot));
	set_pte_at(mm, addr, pte, entry);
	update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */

	retval = 0;
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

N
Nick Piggin 已提交
1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342
/**
 * vm_insert_pfn - insert single pfn into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @pfn: source kernel pfn
 *
 * Similar to vm_inert_page, this allows drivers to insert individual pages
 * they've allocated into a user vma. Same comments apply.
 *
 * This function should only be called from a vm_ops->fault handler, and
 * in that case the handler should return NULL.
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1343
			unsigned long pfn)
N
Nick Piggin 已提交
1344
{
N
Nick Piggin 已提交
1345 1346 1347 1348 1349 1350
	/*
	 * Technically, architectures with pte_special can avoid all these
	 * restrictions (same for remap_pfn_range).  However we would like
	 * consistency in testing and feature parity among all, so we should
	 * try to keep these invariants in place for everybody.
	 */
J
Jared Hulbert 已提交
1351 1352 1353 1354 1355
	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
						(VM_PFNMAP|VM_MIXEDMAP));
	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
N
Nick Piggin 已提交
1356

N
Nick Piggin 已提交
1357 1358 1359 1360 1361
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1362

N
Nick Piggin 已提交
1363 1364 1365 1366
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn)
{
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1367

N
Nick Piggin 已提交
1368 1369
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1370

N
Nick Piggin 已提交
1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383
	/*
	 * If we don't have pte special, then we have to use the pfn_valid()
	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
	 * refcount the page if pfn_valid is true (hence insert_page rather
	 * than insert_pfn).
	 */
	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
		struct page *page;

		page = pfn_to_page(pfn);
		return insert_page(vma, addr, page, vma->vm_page_prot);
	}
	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
N
Nick Piggin 已提交
1384
}
N
Nick Piggin 已提交
1385
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1386

L
Linus Torvalds 已提交
1387 1388 1389 1390 1391 1392 1393 1394 1395 1396
/*
 * maps a range of physical memory into the requested pages. the old
 * mappings are removed. any references to nonexistent pages results
 * in null mappings (currently treated as "copy-on-access")
 */
static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pte_t *pte;
H
Hugh Dickins 已提交
1397
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1398

H
Hugh Dickins 已提交
1399
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1400 1401
	if (!pte)
		return -ENOMEM;
1402
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1403 1404
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1405
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1406 1407
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1408
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1409
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452
	return 0;
}

static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pmd_t *pmd;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		if (remap_pte_range(mm, pmd, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pmd++, addr = next, addr != end);
	return 0;
}

static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pud_t *pud;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		if (remap_pmd_range(mm, pud, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pud++, addr = next, addr != end);
	return 0;
}

1453 1454 1455 1456 1457 1458 1459 1460 1461 1462
/**
 * remap_pfn_range - remap kernel memory to userspace
 * @vma: user vma to map to
 * @addr: target user address to start at
 * @pfn: physical address of kernel memory
 * @size: size of map area
 * @prot: page protection flags for this mapping
 *
 *  Note: this is only safe if the mm semaphore is held when called.
 */
L
Linus Torvalds 已提交
1463 1464 1465 1466 1467
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
		    unsigned long pfn, unsigned long size, pgprot_t prot)
{
	pgd_t *pgd;
	unsigned long next;
1468
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1469 1470 1471 1472 1473 1474 1475 1476
	struct mm_struct *mm = vma->vm_mm;
	int err;

	/*
	 * Physically remapped pages are special. Tell the
	 * rest of the world about it:
	 *   VM_IO tells people not to look at these pages
	 *	(accesses can have side effects).
H
Hugh Dickins 已提交
1477 1478 1479 1480 1481
	 *   VM_RESERVED is specified all over the place, because
	 *	in 2.4 it kept swapout's vma scan off this vma; but
	 *	in 2.6 the LRU scan won't even find its pages, so this
	 *	flag means no more than count its pages in reserved_vm,
	 * 	and omit it from core dump, even when VM_IO turned off.
1482 1483 1484
	 *   VM_PFNMAP tells the core MM that the base pages are just
	 *	raw PFN mappings, and do not have a "struct page" associated
	 *	with them.
L
Linus Torvalds 已提交
1485 1486 1487 1488
	 *
	 * There's a horrible special case to handle copy-on-write
	 * behaviour that some programs depend on. We mark the "original"
	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
L
Linus Torvalds 已提交
1489
	 */
1490
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1491
		if (addr != vma->vm_start || end != vma->vm_end)
1492
			return -EINVAL;
L
Linus Torvalds 已提交
1493 1494 1495
		vma->vm_pgoff = pfn;
	}

1496
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512

	BUG_ON(addr >= end);
	pfn -= addr >> PAGE_SHIFT;
	pgd = pgd_offset(mm, addr);
	flush_cache_range(vma, addr, end);
	do {
		next = pgd_addr_end(addr, end);
		err = remap_pud_range(mm, pgd, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1513 1514 1515 1516 1517 1518
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pte_t *pte;
	int err;
1519
	pgtable_t token;
1520
	spinlock_t *uninitialized_var(ptl);
1521 1522 1523 1524 1525 1526 1527 1528 1529

	pte = (mm == &init_mm) ?
		pte_alloc_kernel(pmd, addr) :
		pte_alloc_map_lock(mm, pmd, addr, &ptl);
	if (!pte)
		return -ENOMEM;

	BUG_ON(pmd_huge(*pmd));

1530
	token = pmd_pgtable(*pmd);
1531 1532

	do {
1533
		err = fn(pte, token, addr, data);
1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 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
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

	if (mm != &init_mm)
		pte_unmap_unlock(pte-1, ptl);
	return err;
}

static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pmd_t *pmd;
	unsigned long next;
	int err;

	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);
	return err;
}

static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pud_t *pud;
	unsigned long next;
	int err;

	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
		if (err)
			break;
	} while (pud++, addr = next, addr != end);
	return err;
}

/*
 * Scan a region of virtual memory, filling in page tables as necessary
 * and calling a provided function on each leaf page table.
 */
int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
			unsigned long size, pte_fn_t fn, void *data)
{
	pgd_t *pgd;
	unsigned long next;
	unsigned long end = addr + size;
	int err;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1607 1608 1609 1610 1611 1612 1613 1614 1615
/*
 * handle_pte_fault chooses page fault handler according to an entry
 * which was read non-atomically.  Before making any commitment, on
 * those architectures or configurations (e.g. i386 with PAE) which
 * might give a mix of unmatched parts, do_swap_page and do_file_page
 * must check under lock before unmapping the pte and proceeding
 * (but do_wp_page is only called after already making such a check;
 * and do_anonymous_page and do_no_page can safely check later on).
 */
H
Hugh Dickins 已提交
1616
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1617 1618 1619 1620 1621
				pte_t *page_table, pte_t orig_pte)
{
	int same = 1;
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
	if (sizeof(pte_t) > sizeof(unsigned long)) {
H
Hugh Dickins 已提交
1622 1623
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1624
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1625
		spin_unlock(ptl);
1626 1627 1628 1629 1630 1631
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644
/*
 * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
 * servicing faults for write access.  In the normal case, do always want
 * pte_mkwrite.  But get_user_pages can cause write faults for mappings
 * that do not have writing enabled, when used by access_process_vm.
 */
static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
{
	if (likely(vma->vm_flags & VM_WRITE))
		pte = pte_mkwrite(pte);
	return pte;
}

1645
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1646 1647 1648 1649 1650 1651 1652 1653 1654
{
	/*
	 * If the source page was a PFN mapping, we don't have
	 * a "struct page" for it. We do a best-effort copy by
	 * just copying from the original user address. If that
	 * fails, we just zero-fill it. Live with it.
	 */
	if (unlikely(!src)) {
		void *kaddr = kmap_atomic(dst, KM_USER0);
L
Linus Torvalds 已提交
1655 1656 1657 1658 1659 1660 1661 1662 1663
		void __user *uaddr = (void __user *)(va & PAGE_MASK);

		/*
		 * This really shouldn't fail, because the page is there
		 * in the page tables. But it might just be unreadable,
		 * in which case we just give up and fill the result with
		 * zeroes.
		 */
		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1664 1665
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1666
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1667 1668
	} else
		copy_user_highpage(dst, src, va, vma);
1669 1670
}

L
Linus Torvalds 已提交
1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684
/*
 * This routine handles present pages, when users try to write
 * to a shared page. It is done by copying the page to a new address
 * and decrementing the shared-page counter for the old page.
 *
 * Note that this routine assumes that the protection checks have been
 * done by the caller (the low-level page fault routine in most cases).
 * Thus we can safely just mark it writable once we've done any necessary
 * COW.
 *
 * We also mark the page dirty at this point even though the page will
 * change only once the write actually happens. This avoids a few races,
 * and potentially makes it more efficient.
 *
1685 1686 1687
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), with pte both mapped and locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
1688
 */
1689 1690
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1691
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1692
{
1693
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1694
	pte_t entry;
N
Nick Piggin 已提交
1695
	int reuse = 0, ret = 0;
1696
	int page_mkwrite = 0;
1697
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1698

1699
	old_page = vm_normal_page(vma, address, orig_pte);
1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710
	if (!old_page) {
		/*
		 * VM_MIXEDMAP !pfn_valid() case
		 *
		 * We should not cow pages in a shared writeable mapping.
		 * Just mark the pages writable as we can't do any dirty
		 * accounting on raw pfn maps.
		 */
		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
				     (VM_WRITE|VM_SHARED))
			goto reuse;
1711
		goto gotten;
1712
	}
L
Linus Torvalds 已提交
1713

1714
	/*
P
Peter Zijlstra 已提交
1715 1716
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1717
	 */
P
Peter Zijlstra 已提交
1718 1719 1720 1721 1722 1723
	if (PageAnon(old_page)) {
		if (!TestSetPageLocked(old_page)) {
			reuse = can_share_swap_page(old_page);
			unlock_page(old_page);
		}
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1724
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1725 1726 1727 1728 1729
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
			/*
			 * Notify the address space that the page is about to
			 * become writable so that it can prohibit this or wait
			 * for the page to get into an appropriate state.
			 *
			 * We do this without the lock held, so that it can
			 * sleep if it needs to.
			 */
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);

			if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
				goto unwritable_page;

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
1753
			page_cache_release(old_page);
1754 1755
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1756 1757

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1758
		}
1759 1760
		dirty_page = old_page;
		get_page(dirty_page);
1761 1762 1763 1764
		reuse = 1;
	}

	if (reuse) {
1765
reuse:
1766 1767 1768
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1769
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1770
			update_mmu_cache(vma, address, entry);
1771 1772
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1773 1774 1775 1776 1777
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1778
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1779
gotten:
1780
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1781 1782

	if (unlikely(anon_vma_prepare(vma)))
1783
		goto oom;
N
Nick Piggin 已提交
1784 1785 1786 1787 1788
	VM_BUG_ON(old_page == ZERO_PAGE(0));
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
	if (!new_page)
		goto oom;
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
1789
	__SetPageUptodate(new_page);
1790

1791
	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
1792 1793
		goto oom_free_new;

L
Linus Torvalds 已提交
1794 1795 1796
	/*
	 * Re-check the pte - we dropped the lock
	 */
1797
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1798
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1799 1800 1801 1802 1803 1804
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1805
			inc_mm_counter(mm, anon_rss);
1806
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1807 1808
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1809 1810 1811 1812 1813 1814 1815 1816
		/*
		 * Clear the pte entry and flush it first, before updating the
		 * pte with the new entry. This will avoid a race condition
		 * seen in the presence of one thread doing SMC and another
		 * thread doing COW.
		 */
		ptep_clear_flush(vma, address, page_table);
		set_pte_at(mm, address, page_table, entry);
1817
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1818
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1819
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1820

N
Nick Piggin 已提交
1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846
		if (old_page) {
			/*
			 * Only after switching the pte to the new page may
			 * we remove the mapcount here. Otherwise another
			 * process may come and find the rmap count decremented
			 * before the pte is switched to the new page, and
			 * "reuse" the old page writing into it while our pte
			 * here still points into it and can be read by other
			 * threads.
			 *
			 * The critical issue is to order this
			 * page_remove_rmap with the ptp_clear_flush above.
			 * Those stores are ordered by (if nothing else,)
			 * the barrier present in the atomic_add_negative
			 * in page_remove_rmap.
			 *
			 * Then the TLB flush in ptep_clear_flush ensures that
			 * no process can access the old page before the
			 * decremented mapcount is visible. And the old page
			 * cannot be reused until after the decremented
			 * mapcount is visible. So transitively, TLBs to
			 * old page will be flushed before it can be reused.
			 */
			page_remove_rmap(old_page, vma);
		}

L
Linus Torvalds 已提交
1847 1848
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1849
		ret |= VM_FAULT_WRITE;
1850 1851 1852
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
1853 1854 1855 1856
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1857
unlock:
1858
	pte_unmap_unlock(page_table, ptl);
1859
	if (dirty_page) {
1860 1861 1862
		if (vma->vm_file)
			file_update_time(vma->vm_file);

1863 1864 1865 1866 1867 1868 1869 1870 1871
		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
		 * do_no_page is protected similarly.
		 */
		wait_on_page_locked(dirty_page);
1872
		set_page_dirty_balance(dirty_page, page_mkwrite);
1873 1874
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1875
	return ret;
1876
oom_free_new:
1877
	page_cache_release(new_page);
1878
oom:
H
Hugh Dickins 已提交
1879 1880
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1881
	return VM_FAULT_OOM;
1882 1883 1884 1885

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912
}

/*
 * Helper functions for unmap_mapping_range().
 *
 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
 *
 * We have to restart searching the prio_tree whenever we drop the lock,
 * since the iterator is only valid while the lock is held, and anyway
 * a later vma might be split and reinserted earlier while lock dropped.
 *
 * The list of nonlinear vmas could be handled more efficiently, using
 * a placeholder, but handle it in the same way until a need is shown.
 * It is important to search the prio_tree before nonlinear list: a vma
 * may become nonlinear and be shifted from prio_tree to nonlinear list
 * while the lock is dropped; but never shifted from list to prio_tree.
 *
 * In order to make forward progress despite restarting the search,
 * vm_truncate_count is used to mark a vma as now dealt with, so we can
 * quickly skip it next time around.  Since the prio_tree search only
 * shows us those vmas affected by unmapping the range in question, we
 * can't efficiently keep all vmas in step with mapping->truncate_count:
 * so instead reset them all whenever it wraps back to 0 (then go to 1).
 * mapping->truncate_count and vma->vm_truncate_count are protected by
 * i_mmap_lock.
 *
 * In order to make forward progress despite repeatedly restarting some
1913
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939
 * and restart from that address when we reach that vma again.  It might
 * have been split or merged, shrunk or extended, but never shifted: so
 * restart_addr remains valid so long as it remains in the vma's range.
 * unmap_mapping_range forces truncate_count to leap over page-aligned
 * values so we can save vma's restart_addr in its truncate_count field.
 */
#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))

static void reset_vma_truncate_counts(struct address_space *mapping)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;

	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
		vma->vm_truncate_count = 0;
	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
		vma->vm_truncate_count = 0;
}

static int unmap_mapping_range_vma(struct vm_area_struct *vma,
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
	unsigned long restart_addr;
	int need_break;

1940 1941
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
1942
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
1943 1944
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
1945 1946
	 */

L
Linus Torvalds 已提交
1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957
again:
	restart_addr = vma->vm_truncate_count;
	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
		start_addr = restart_addr;
		if (start_addr >= end_addr) {
			/* Top of vma has been split off since last time */
			vma->vm_truncate_count = details->truncate_count;
			return 0;
		}
	}

1958 1959
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
1960
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
1961

1962
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1963 1964 1965 1966 1967 1968
		/* We have now completed this vma: mark it so */
		vma->vm_truncate_count = details->truncate_count;
		if (!need_break)
			return 0;
	} else {
		/* Note restart_addr in vma's truncate_count field */
1969
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035
		if (!need_break)
			goto again;
	}

	spin_unlock(details->i_mmap_lock);
	cond_resched();
	spin_lock(details->i_mmap_lock);
	return -EINTR;
}

static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;
	pgoff_t vba, vea, zba, zea;

restart:
	vma_prio_tree_foreach(vma, &iter, root,
			details->first_index, details->last_index) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;

		vba = vma->vm_pgoff;
		vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
		/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
		zba = details->first_index;
		if (zba < vba)
			zba = vba;
		zea = details->last_index;
		if (zea > vea)
			zea = vea;

		if (unmap_mapping_range_vma(vma,
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
				details) < 0)
			goto restart;
	}
}

static inline void unmap_mapping_range_list(struct list_head *head,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;

	/*
	 * In nonlinear VMAs there is no correspondence between virtual address
	 * offset and file offset.  So we must perform an exhaustive search
	 * across *all* the pages in each nonlinear VMA, not just the pages
	 * whose virtual address lies outside the file truncation point.
	 */
restart:
	list_for_each_entry(vma, head, shared.vm_set.list) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;
		details->nonlinear_vma = vma;
		if (unmap_mapping_range_vma(vma, vma->vm_start,
					vma->vm_end, details) < 0)
			goto restart;
	}
}

/**
2036
 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
M
Martin Waitz 已提交
2037
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
 * boundary.  Note that this is different from vmtruncate(), which
 * must keep the partial page.  In contrast, we must get rid of
 * partial pages.
 * @holelen: size of prospective hole in bytes.  This will be rounded
 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
 * end of the file.
 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
 * but 0 when invalidating pagecache, don't throw away private data.
 */
void unmap_mapping_range(struct address_space *mapping,
		loff_t const holebegin, loff_t const holelen, int even_cows)
{
	struct zap_details details;
	pgoff_t hba = holebegin >> PAGE_SHIFT;
	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;

	/* Check for overflow. */
	if (sizeof(holelen) > sizeof(hlen)) {
		long long holeend =
			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
		if (holeend & ~(long long)ULONG_MAX)
			hlen = ULONG_MAX - hba + 1;
	}

	details.check_mapping = even_cows? NULL: mapping;
	details.nonlinear_vma = NULL;
	details.first_index = hba;
	details.last_index = hba + hlen - 1;
	if (details.last_index < details.first_index)
		details.last_index = ULONG_MAX;
	details.i_mmap_lock = &mapping->i_mmap_lock;

	spin_lock(&mapping->i_mmap_lock);

2074
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090
	mapping->truncate_count++;
	if (unlikely(is_restart_addr(mapping->truncate_count))) {
		if (mapping->truncate_count == 0)
			reset_vma_truncate_counts(mapping);
		mapping->truncate_count++;
	}
	details.truncate_count = mapping->truncate_count;

	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
	spin_unlock(&mapping->i_mmap_lock);
}
EXPORT_SYMBOL(unmap_mapping_range);

2091 2092 2093 2094
/**
 * vmtruncate - unmap mappings "freed" by truncate() syscall
 * @inode: inode of the file used
 * @offset: file offset to start truncating
L
Linus Torvalds 已提交
2095 2096 2097 2098 2099 2100 2101
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode * inode, loff_t offset)
{
C
Christoph Hellwig 已提交
2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112
	if (inode->i_size < offset) {
		unsigned long limit;

		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
		if (limit != RLIM_INFINITY && offset > limit)
			goto out_sig;
		if (offset > inode->i_sb->s_maxbytes)
			goto out_big;
		i_size_write(inode, offset);
	} else {
		struct address_space *mapping = inode->i_mapping;
L
Linus Torvalds 已提交
2113

C
Christoph Hellwig 已提交
2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135
		/*
		 * truncation of in-use swapfiles is disallowed - it would
		 * cause subsequent swapout to scribble on the now-freed
		 * blocks.
		 */
		if (IS_SWAPFILE(inode))
			return -ETXTBSY;
		i_size_write(inode, offset);

		/*
		 * unmap_mapping_range is called twice, first simply for
		 * efficiency so that truncate_inode_pages does fewer
		 * single-page unmaps.  However after this first call, and
		 * before truncate_inode_pages finishes, it is possible for
		 * private pages to be COWed, which remain after
		 * truncate_inode_pages finishes, hence the second
		 * unmap_mapping_range call must be made for correctness.
		 */
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
		truncate_inode_pages(mapping, offset);
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	}
2136

L
Linus Torvalds 已提交
2137 2138 2139
	if (inode->i_op && inode->i_op->truncate)
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2140

L
Linus Torvalds 已提交
2141 2142 2143 2144 2145 2146 2147
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159
int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
{
	struct address_space *mapping = inode->i_mapping;

	/*
	 * If the underlying filesystem is not going to provide
	 * a way to truncate a range of blocks (punch a hole) -
	 * we should return failure right now.
	 */
	if (!inode->i_op || !inode->i_op->truncate_range)
		return -ENOSYS;

2160
	mutex_lock(&inode->i_mutex);
2161 2162 2163
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2164
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2165 2166
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2167
	mutex_unlock(&inode->i_mutex);
2168 2169 2170 2171

	return 0;
}

L
Linus Torvalds 已提交
2172
/*
2173 2174 2175
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2176
 */
2177 2178 2179
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2180
{
2181
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2182
	struct page *page;
2183
	swp_entry_t entry;
L
Linus Torvalds 已提交
2184
	pte_t pte;
N
Nick Piggin 已提交
2185
	int ret = 0;
L
Linus Torvalds 已提交
2186

H
Hugh Dickins 已提交
2187
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2188
		goto out;
2189 2190

	entry = pte_to_swp_entry(orig_pte);
2191 2192 2193 2194
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2195
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2196 2197
	page = lookup_swap_cache(entry);
	if (!page) {
2198
		grab_swap_token(); /* Contend for token _before_ read-in */
2199 2200
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2201 2202
		if (!page) {
			/*
2203 2204
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2205
			 */
2206
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2207 2208
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2209
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2210
			goto unlock;
L
Linus Torvalds 已提交
2211 2212 2213 2214
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2215
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2216 2217
	}

2218
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2219 2220 2221 2222 2223
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
		ret = VM_FAULT_OOM;
		goto out;
	}

L
Linus Torvalds 已提交
2224 2225
	mark_page_accessed(page);
	lock_page(page);
2226
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2227 2228

	/*
2229
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2230
	 */
2231
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2232
	if (unlikely(!pte_same(*page_table, orig_pte)))
2233 2234 2235 2236 2237
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2238 2239 2240 2241
	}

	/* The page isn't present yet, go ahead with the fault. */

2242
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2243 2244 2245 2246 2247 2248 2249 2250 2251 2252
	pte = mk_pte(page, vma->vm_page_prot);
	if (write_access && can_share_swap_page(page)) {
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
		write_access = 0;
	}

	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
	page_add_anon_rmap(page, vma, address);

2253 2254 2255 2256 2257
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2258
	if (write_access) {
2259 2260 2261
		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
		if (ret & VM_FAULT_ERROR)
			ret &= VM_FAULT_ERROR;
L
Linus Torvalds 已提交
2262 2263 2264 2265 2266
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2267
unlock:
2268
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2269 2270
out:
	return ret;
2271
out_nomap:
2272
	mem_cgroup_uncharge_page(page);
2273
	pte_unmap_unlock(page_table, ptl);
2274 2275
	unlock_page(page);
	page_cache_release(page);
2276
	return ret;
L
Linus Torvalds 已提交
2277 2278 2279
}

/*
2280 2281 2282
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2283
 */
2284 2285 2286
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access)
L
Linus Torvalds 已提交
2287
{
2288 2289
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2290 2291
	pte_t entry;

N
Nick Piggin 已提交
2292 2293
	/* Allocate our own private page. */
	pte_unmap(page_table);
2294

N
Nick Piggin 已提交
2295 2296 2297 2298 2299
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
N
Nick Piggin 已提交
2300
	__SetPageUptodate(page);
2301

2302
	if (mem_cgroup_charge(page, mm, GFP_KERNEL))
2303 2304
		goto oom_free_page;

N
Nick Piggin 已提交
2305 2306
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2307

N
Nick Piggin 已提交
2308 2309 2310 2311 2312 2313
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!pte_none(*page_table))
		goto release;
	inc_mm_counter(mm, anon_rss);
	lru_cache_add_active(page);
	page_add_new_anon_rmap(page, vma, address);
2314
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2315 2316

	/* No need to invalidate - it was non-present before */
2317 2318
	update_mmu_cache(vma, address, entry);
unlock:
2319
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2320
	return 0;
2321
release:
2322
	mem_cgroup_uncharge_page(page);
2323 2324
	page_cache_release(page);
	goto unlock;
2325
oom_free_page:
2326
	page_cache_release(page);
2327
oom:
L
Linus Torvalds 已提交
2328 2329 2330 2331
	return VM_FAULT_OOM;
}

/*
2332
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2333
 * tries to share with existing pages, but makes a separate copy if
2334 2335
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2336 2337 2338 2339
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2340
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2341
 * but allow concurrent faults), and pte neither mapped nor locked.
2342
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2343
 */
2344
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2345
		unsigned long address, pmd_t *pmd,
2346
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2347
{
2348
	pte_t *page_table;
2349
	spinlock_t *ptl;
N
Nick Piggin 已提交
2350
	struct page *page;
L
Linus Torvalds 已提交
2351 2352
	pte_t entry;
	int anon = 0;
2353
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2354 2355
	struct vm_fault vmf;
	int ret;
2356
	int page_mkwrite = 0;
2357

N
Nick Piggin 已提交
2358 2359 2360 2361
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2362

N
Nick Piggin 已提交
2363 2364 2365
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2366

2367
	/*
N
Nick Piggin 已提交
2368
	 * For consistency in subsequent calls, make the faulted page always
2369 2370
	 * locked.
	 */
N
Nick Piggin 已提交
2371
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2372
		lock_page(vmf.page);
2373
	else
N
Nick Piggin 已提交
2374
		VM_BUG_ON(!PageLocked(vmf.page));
2375

L
Linus Torvalds 已提交
2376 2377 2378
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2379
	page = vmf.page;
2380
	if (flags & FAULT_FLAG_WRITE) {
2381
		if (!(vma->vm_flags & VM_SHARED)) {
2382
			anon = 1;
2383
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2384
				ret = VM_FAULT_OOM;
2385
				goto out;
2386
			}
N
Nick Piggin 已提交
2387 2388
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2389
			if (!page) {
N
Nick Piggin 已提交
2390
				ret = VM_FAULT_OOM;
2391
				goto out;
2392
			}
N
Nick Piggin 已提交
2393
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2394
			__SetPageUptodate(page);
2395
		} else {
2396 2397
			/*
			 * If the page will be shareable, see if the backing
2398
			 * address space wants to know that the page is about
2399 2400
			 * to become writable
			 */
2401 2402 2403
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2404 2405
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2406 2407 2408
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2409 2410 2411 2412 2413 2414 2415 2416
				/*
				 * XXX: this is not quite right (racy vs
				 * invalidate) to unlock and relock the page
				 * like this, however a better fix requires
				 * reworking page_mkwrite locking API, which
				 * is better done later.
				 */
				if (!page->mapping) {
N
Nick Piggin 已提交
2417
					ret = 0;
N
Nick Piggin 已提交
2418 2419 2420
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2421
				page_mkwrite = 1;
2422 2423
			}
		}
2424

L
Linus Torvalds 已提交
2425 2426
	}

2427
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2428 2429 2430 2431
		ret = VM_FAULT_OOM;
		goto out;
	}

2432
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
	 * Note that if write_access is true, we either now have
	 * an exclusive copy of the page, or this is a shared mapping,
	 * so we can make it writable and dirty to avoid having to
	 * handle that later.
	 */
	/* Only go through if we didn't race with anybody else... */
2445
	if (likely(pte_same(*page_table, orig_pte))) {
2446 2447
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2448
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2449 2450 2451
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2452 2453 2454
                        inc_mm_counter(mm, anon_rss);
                        lru_cache_add_active(page);
                        page_add_new_anon_rmap(page, vma, address);
2455
		} else {
2456
			inc_mm_counter(mm, file_rss);
2457
			page_add_file_rmap(page);
2458
			if (flags & FAULT_FLAG_WRITE) {
2459
				dirty_page = page;
2460 2461
				get_page(dirty_page);
			}
2462
		}
2463 2464 2465

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2466
	} else {
2467
		mem_cgroup_uncharge_page(page);
2468 2469 2470
		if (anon)
			page_cache_release(page);
		else
2471
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2472 2473
	}

2474
	pte_unmap_unlock(page_table, ptl);
2475 2476

out:
N
Nick Piggin 已提交
2477
	unlock_page(vmf.page);
2478
out_unlocked:
2479
	if (anon)
N
Nick Piggin 已提交
2480
		page_cache_release(vmf.page);
2481
	else if (dirty_page) {
2482 2483 2484
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2485
		set_page_dirty_balance(dirty_page, page_mkwrite);
2486 2487
		put_page(dirty_page);
	}
2488

N
Nick Piggin 已提交
2489
	return ret;
2490
}
2491

2492 2493 2494 2495 2496
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2497
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2498 2499
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2500 2501
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2502 2503
}

L
Linus Torvalds 已提交
2504

J
Jes Sorensen 已提交
2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529
/*
 * do_no_pfn() tries to create a new page mapping for a page without
 * a struct_page backing it
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
 *
 * It is expected that the ->nopfn handler always returns the same pfn
 * for a given virtual mapping.
 *
 * Mark this `noinline' to prevent it from bloating the main pagefault code.
 */
static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
		     unsigned long address, pte_t *page_table, pmd_t *pmd,
		     int write_access)
{
	spinlock_t *ptl;
	pte_t entry;
	unsigned long pfn;

	pte_unmap(page_table);
J
Jared Hulbert 已提交
2530 2531
	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
J
Jes Sorensen 已提交
2532 2533

	pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
J
Jared Hulbert 已提交
2534 2535 2536

	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));

2537
	if (unlikely(pfn == NOPFN_OOM))
J
Jes Sorensen 已提交
2538
		return VM_FAULT_OOM;
2539
	else if (unlikely(pfn == NOPFN_SIGBUS))
J
Jes Sorensen 已提交
2540
		return VM_FAULT_SIGBUS;
2541
	else if (unlikely(pfn == NOPFN_REFAULT))
N
Nick Piggin 已提交
2542
		return 0;
J
Jes Sorensen 已提交
2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553

	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);

	/* Only go through if we didn't race with anybody else... */
	if (pte_none(*page_table)) {
		entry = pfn_pte(pfn, vma->vm_page_prot);
		if (write_access)
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
	}
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2554
	return 0;
J
Jes Sorensen 已提交
2555 2556
}

L
Linus Torvalds 已提交
2557 2558 2559 2560
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2561 2562 2563 2564
 *
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2565
 */
N
Nick Piggin 已提交
2566
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2567 2568
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2569
{
N
Nick Piggin 已提交
2570 2571
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2572
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2573

H
Hugh Dickins 已提交
2574
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2575
		return 0;
L
Linus Torvalds 已提交
2576

N
Nick Piggin 已提交
2577 2578
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2579 2580 2581
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2582
		print_bad_pte(vma, orig_pte, address);
2583 2584 2585 2586
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2587
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598
}

/*
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 *
H
Hugh Dickins 已提交
2599 2600 2601
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2602 2603
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2604 2605
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2606 2607
{
	pte_t entry;
2608
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2609

2610
	entry = *pte;
L
Linus Torvalds 已提交
2611
	if (!pte_present(entry)) {
2612
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2613
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2614
				if (likely(vma->vm_ops->fault))
2615 2616
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2617 2618 2619 2620 2621 2622
				if (unlikely(vma->vm_ops->nopfn))
					return do_no_pfn(mm, vma, address, pte,
							 pmd, write_access);
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2623
		}
L
Linus Torvalds 已提交
2624
		if (pte_file(entry))
N
Nick Piggin 已提交
2625
			return do_nonlinear_fault(mm, vma, address,
2626 2627 2628
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2629 2630
	}

H
Hugh Dickins 已提交
2631
	ptl = pte_lockptr(mm, pmd);
2632 2633 2634
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2635 2636
	if (write_access) {
		if (!pte_write(entry))
2637 2638
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2639 2640 2641
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2642
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653
		update_mmu_cache(vma, address, entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2654 2655
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2656
	return 0;
L
Linus Torvalds 已提交
2657 2658 2659 2660 2661
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2662
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2663 2664 2665 2666 2667 2668 2669 2670 2671
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2672
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2673

2674 2675
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2676 2677 2678 2679

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2680
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2681 2682
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2683
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2684 2685
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2686
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2687

H
Hugh Dickins 已提交
2688
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2689 2690 2691 2692 2693
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2694
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2695
 */
2696
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2697
{
H
Hugh Dickins 已提交
2698 2699
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2700
		return -ENOMEM;
L
Linus Torvalds 已提交
2701

2702 2703
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2704
	spin_lock(&mm->page_table_lock);
2705
	if (pgd_present(*pgd))		/* Another has populated it */
2706
		pud_free(mm, new);
2707 2708
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2709
	spin_unlock(&mm->page_table_lock);
2710
	return 0;
L
Linus Torvalds 已提交
2711 2712 2713 2714 2715 2716
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2717
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2718
 */
2719
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2720
{
H
Hugh Dickins 已提交
2721 2722
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2723
		return -ENOMEM;
L
Linus Torvalds 已提交
2724

2725 2726
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2727
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2728
#ifndef __ARCH_HAS_4LEVEL_HACK
2729
	if (pud_present(*pud))		/* Another has populated it */
2730
		pmd_free(mm, new);
2731 2732
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2733
#else
2734
	if (pgd_present(*pud))		/* Another has populated it */
2735
		pmd_free(mm, new);
2736 2737
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2738
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2739
	spin_unlock(&mm->page_table_lock);
2740
	return 0;
2741
}
L
Linus Torvalds 已提交
2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752
#endif /* __PAGETABLE_PMD_FOLDED */

int make_pages_present(unsigned long addr, unsigned long end)
{
	int ret, len, write;
	struct vm_area_struct * vma;

	vma = find_vma(current->mm, addr);
	if (!vma)
		return -1;
	write = (vma->vm_flags & VM_WRITE) != 0;
2753 2754
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2755
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2756 2757 2758 2759 2760 2761 2762 2763 2764 2765
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
	if (ret < 0)
		return ret;
	return ret == len ? 0 : -1;
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2766
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2767 2768 2769 2770 2771 2772

static int __init gate_vma_init(void)
{
	gate_vma.vm_mm = NULL;
	gate_vma.vm_start = FIXADDR_USER_START;
	gate_vma.vm_end = FIXADDR_USER_END;
R
Roland McGrath 已提交
2773 2774
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2775 2776 2777 2778 2779 2780 2781
	/*
	 * Make sure the vDSO gets into every core dump.
	 * Dumping its contents makes post-mortem fully interpretable later
	 * without matching up the same kernel and hardware config to see
	 * what PC values meant.
	 */
	gate_vma.vm_flags |= VM_ALWAYSDUMP;
L
Linus Torvalds 已提交
2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805
	return 0;
}
__initcall(gate_vma_init);
#endif

struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
#ifdef AT_SYSINFO_EHDR
	return &gate_vma;
#else
	return NULL;
#endif
}

int in_gate_area_no_task(unsigned long addr)
{
#ifdef AT_SYSINFO_EHDR
	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
		return 1;
#endif
	return 0;
}

#endif	/* __HAVE_ARCH_GATE_AREA */
2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823

/*
 * Access another process' address space.
 * Source/target buffer must be kernel space,
 * Do not walk the page table directly, use get_user_pages
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	struct page *page;
	void *old_buf = buf;

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

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
2824
	/* ignore errors, just check how much was successfully transferred */
2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858
	while (len) {
		int bytes, ret, offset;
		void *maddr;

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
		if (ret <= 0)
			break;

		bytes = len;
		offset = addr & (PAGE_SIZE-1);
		if (bytes > PAGE_SIZE-offset)
			bytes = PAGE_SIZE-offset;

		maddr = kmap(page);
		if (write) {
			copy_to_user_page(vma, page, addr,
					  maddr + offset, buf, bytes);
			set_page_dirty_lock(page);
		} else {
			copy_from_user_page(vma, page, addr,
					    buf, maddr + offset, bytes);
		}
		kunmap(page);
		page_cache_release(page);
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
2859 2860 2861 2862 2863 2864 2865 2866 2867

/*
 * Print the name of a VMA.
 */
void print_vma_addr(char *prefix, unsigned long ip)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;

2868 2869 2870 2871 2872 2873 2874
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

2875 2876 2877 2878 2879 2880 2881 2882
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, ip);
	if (vma && vma->vm_file) {
		struct file *f = vma->vm_file;
		char *buf = (char *)__get_free_page(GFP_KERNEL);
		if (buf) {
			char *p, *s;

2883
			p = d_path(&f->f_path, buf, PAGE_SIZE);
2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896
			if (IS_ERR(p))
				p = "?";
			s = strrchr(p, '/');
			if (s)
				p = s+1;
			printk("%s%s[%lx+%lx]", prefix, p,
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
	up_read(&current->mm->mmap_sem);
}