memory.c 76.1 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>
L
Linus Torvalds 已提交
53 54 55 56 57 58 59 60 61 62

#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
63
#ifndef CONFIG_NEED_MULTIPLE_NODES
L
Linus Torvalds 已提交
64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84
/* 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);

85 86 87 88 89
int randomize_va_space __read_mostly = 1;

static int __init disable_randmaps(char *s)
{
	randomize_va_space = 0;
90
	return 1;
91 92 93 94
}
__setup("norandmaps", disable_randmaps);


L
Linus Torvalds 已提交
95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122
/*
 * 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.
 */
123
static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
L
Linus Torvalds 已提交
124
{
125 126
	struct page *page = pmd_page(*pmd);
	pmd_clear(pmd);
H
Hugh Dickins 已提交
127
	pte_lock_deinit(page);
128
	pte_free_tlb(tlb, page);
129
	dec_zone_page_state(page, NR_PAGETABLE);
130
	tlb->mm->nr_ptes--;
L
Linus Torvalds 已提交
131 132
}

133 134 135
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
136 137 138
{
	pmd_t *pmd;
	unsigned long next;
139
	unsigned long start;
L
Linus Torvalds 已提交
140

141
	start = addr;
L
Linus Torvalds 已提交
142 143 144 145 146
	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			continue;
147
		free_pte_range(tlb, pmd);
L
Linus Torvalds 已提交
148 149
	} while (pmd++, addr = next, addr != end);

150 151 152 153 154 155 156
	start &= PUD_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
L
Linus Torvalds 已提交
157
	}
158 159 160 161 162 163
	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
164 165
}

166 167 168
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
169 170 171
{
	pud_t *pud;
	unsigned long next;
172
	unsigned long start;
L
Linus Torvalds 已提交
173

174
	start = addr;
L
Linus Torvalds 已提交
175 176 177 178 179
	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
180
		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
L
Linus Torvalds 已提交
181 182
	} while (pud++, addr = next, addr != end);

183 184 185 186 187 188 189
	start &= PGDIR_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
L
Linus Torvalds 已提交
190
	}
191 192 193 194 195 196
	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
197 198 199
}

/*
200 201
 * This function frees user-level page tables of a process.
 *
L
Linus Torvalds 已提交
202 203
 * Must be called with pagetable lock held.
 */
204
void free_pgd_range(struct mmu_gather **tlb,
205 206
			unsigned long addr, unsigned long end,
			unsigned long floor, unsigned long ceiling)
L
Linus Torvalds 已提交
207 208 209
{
	pgd_t *pgd;
	unsigned long next;
210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236
	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
237

238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254
	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;
255
	pgd = pgd_offset((*tlb)->mm, addr);
L
Linus Torvalds 已提交
256 257 258 259
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
260
		free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
L
Linus Torvalds 已提交
261
	} while (pgd++, addr = next, addr != end);
262

263
	if (!(*tlb)->fullmm)
264
		flush_tlb_pgtables((*tlb)->mm, start, end);
265 266 267
}

void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
268
		unsigned long floor, unsigned long ceiling)
269 270 271 272 273
{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

274 275 276 277 278 279
		/*
		 * Hide vma from rmap and vmtruncate before freeing pgtables
		 */
		anon_vma_unlink(vma);
		unlink_file_vma(vma);

280
		if (is_vm_hugetlb_page(vma)) {
281
			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
282
				floor, next? next->vm_start: ceiling);
283 284 285 286 287
		} else {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
288
			       && !is_vm_hugetlb_page(next)) {
289 290
				vma = next;
				next = vma->vm_next;
291 292
				anon_vma_unlink(vma);
				unlink_file_vma(vma);
293 294 295 296
			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
297 298
		vma = next;
	}
L
Linus Torvalds 已提交
299 300
}

301
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
302
{
H
Hugh Dickins 已提交
303
	struct page *new = pte_alloc_one(mm, address);
304 305 306
	if (!new)
		return -ENOMEM;

H
Hugh Dickins 已提交
307
	pte_lock_init(new);
H
Hugh Dickins 已提交
308
	spin_lock(&mm->page_table_lock);
H
Hugh Dickins 已提交
309 310
	if (pmd_present(*pmd)) {	/* Another has populated it */
		pte_lock_deinit(new);
311
		pte_free(new);
H
Hugh Dickins 已提交
312
	} else {
L
Linus Torvalds 已提交
313
		mm->nr_ptes++;
314
		inc_zone_page_state(new, NR_PAGETABLE);
L
Linus Torvalds 已提交
315 316
		pmd_populate(mm, pmd, new);
	}
H
Hugh Dickins 已提交
317
	spin_unlock(&mm->page_table_lock);
318
	return 0;
L
Linus Torvalds 已提交
319 320
}

321
int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
322
{
323 324 325 326 327 328 329 330 331 332 333
	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
	if (!new)
		return -ENOMEM;

	spin_lock(&init_mm.page_table_lock);
	if (pmd_present(*pmd))		/* Another has populated it */
		pte_free_kernel(new);
	else
		pmd_populate_kernel(&init_mm, pmd, new);
	spin_unlock(&init_mm.page_table_lock);
	return 0;
L
Linus Torvalds 已提交
334 335
}

336 337 338 339 340 341 342 343
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
344
/*
345 346 347
 * 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
348 349 350 351 352 353 354 355 356 357 358 359 360
 *
 * 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();
}

361 362 363 364 365
static inline int is_cow_mapping(unsigned int flags)
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

H
Hugh Dickins 已提交
366
/*
367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384
 * This function gets the "struct page" associated with a pte.
 *
 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
 * will have each page table entry just pointing to a raw page frame
 * number, and as far as the VM layer is concerned, those do not have
 * pages associated with them - even if the PFN might point to memory
 * that otherwise is perfectly fine and has a "struct page".
 *
 * The way we recognize those mappings is through the rules set up
 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
 * and the vm_pgoff will point to the first PFN mapped: thus every
 * page that is a raw mapping will always honor the rule
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
 * and if that isn't true, the page has been COW'ed (in which case it
 * _does_ have a "struct page" associated with it even if it is in a
 * VM_PFNMAP range).
H
Hugh Dickins 已提交
385
 */
386
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
H
Hugh Dickins 已提交
387
{
388 389
	unsigned long pfn = pte_pfn(pte);

N
Nick Piggin 已提交
390
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
391 392 393
		unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
		if (pfn == vma->vm_pgoff + off)
			return NULL;
394
		if (!is_cow_mapping(vma->vm_flags))
L
Linus Torvalds 已提交
395
			return NULL;
396 397
	}

398 399 400 401 402 403
	/*
	 * Add some anal sanity checks for now. Eventually,
	 * we should just do "return pfn_to_page(pfn)", but
	 * in the meantime we check that we get a valid pfn,
	 * and that the resulting page looks ok.
	 */
404 405 406 407 408 409 410 411 412 413 414 415 416
	if (unlikely(!pfn_valid(pfn))) {
		print_bad_pte(vma, pte, addr);
		return NULL;
	}

	/*
	 * NOTE! We still have PageReserved() pages in the page 
	 * tables. 
	 *
	 * The PAGE_ZERO() pages and various VDSO mappings can
	 * cause them to exist.
	 */
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
417 418
}

L
Linus Torvalds 已提交
419 420 421 422 423 424
/*
 * 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
425
static inline void
L
Linus Torvalds 已提交
426
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
427
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
428
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
429
{
N
Nick Piggin 已提交
430
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
431 432 433 434 435 436
	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)) {
437 438 439
			swp_entry_t entry = pte_to_swp_entry(pte);

			swap_duplicate(entry);
L
Linus Torvalds 已提交
440 441 442
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
443 444 445
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
446 447
				spin_unlock(&mmlist_lock);
			}
448 449 450 451 452 453 454 455 456 457
			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
458
		}
459
		goto out_set_pte;
L
Linus Torvalds 已提交
460 461 462 463 464 465
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
466
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
467
		ptep_set_wrprotect(src_mm, addr, src_pte);
468
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
469 470 471 472 473 474 475 476 477
	}

	/*
	 * 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);
478 479 480 481

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
N
Nick Piggin 已提交
482
		page_dup_rmap(page, vma, addr);
483 484
		rss[!!PageAnon(page)]++;
	}
485 486 487

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
L
Linus Torvalds 已提交
488 489 490 491 492 493 494
}

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
495
	spinlock_t *src_ptl, *dst_ptl;
496
	int progress = 0;
H
Hugh Dickins 已提交
497
	int rss[2];
L
Linus Torvalds 已提交
498 499

again:
500
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
501
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
502 503 504
	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
505
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
506
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
507
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
508 509 510 511 512 513

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
514 515 516
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
H
Hugh Dickins 已提交
517 518
			    need_lockbreak(src_ptl) ||
			    need_lockbreak(dst_ptl))
519 520
				break;
		}
L
Linus Torvalds 已提交
521 522 523 524
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
525
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
526 527 528
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

529
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
530
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
531
	pte_unmap_nested(src_pte - 1);
532
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
533 534
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
L
Linus Torvalds 已提交
535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591
	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;

592 593 594 595 596 597
	/*
	 * 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.
	 */
598
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
599 600 601 602
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618
	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;
}

619
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
620
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
621
				unsigned long addr, unsigned long end,
622
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
623
{
N
Nick Piggin 已提交
624
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
625
	pte_t *pte;
626
	spinlock_t *ptl;
627 628
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
629

630
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
631
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
632 633
	do {
		pte_t ptent = *pte;
634 635
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
636
			continue;
637
		}
638 639 640

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
641
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
642
			struct page *page;
643

644
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662
			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
663
			ptent = ptep_get_and_clear_full(mm, addr, pte,
664
							tlb->fullmm);
L
Linus Torvalds 已提交
665 666 667 668 669 670
			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
671
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
672 673
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
674
				anon_rss--;
675 676 677 678
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
679
					SetPageReferenced(page);
H
Hugh Dickins 已提交
680
				file_rss--;
681
			}
N
Nick Piggin 已提交
682
			page_remove_rmap(page, vma);
L
Linus Torvalds 已提交
683 684 685 686 687 688 689 690 691 692 693
			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));
694
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
695
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
696

H
Hugh Dickins 已提交
697
	add_mm_rss(mm, file_rss, anon_rss);
698
	arch_leave_lazy_mmu_mode();
699
	pte_unmap_unlock(pte - 1, ptl);
700 701

	return addr;
L
Linus Torvalds 已提交
702 703
}

704
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
705
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
706
				unsigned long addr, unsigned long end,
707
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
708 709 710 711 712 713 714
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
715 716
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
717
			continue;
718 719 720 721 722 723
		}
		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
724 725
}

726
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
727
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
728
				unsigned long addr, unsigned long end,
729
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
730 731 732 733 734 735 736
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
737 738
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
739
			continue;
740 741 742 743 744 745
		}
		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
746 747
}

748 749
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
750
				unsigned long addr, unsigned long end,
751
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
752 753 754 755 756 757 758 759 760 761 762 763
{
	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);
764 765
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
766
			continue;
767 768 769 770
		}
		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
771
	tlb_end_vma(tlb, vma);
772 773

	return addr;
L
Linus Torvalds 已提交
774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791
}

#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
 *
792
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
793
 *
794
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
795
 *
796 797
 * 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
798 799 800 801 802 803 804 805 806 807 808
 * 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.
 */
809
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
810 811 812 813
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
814
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
815 816
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
817
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
818
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
819
	int fullmm = (*tlbp)->fullmm;
L
Linus Torvalds 已提交
820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839

	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;
			}

840
			if (unlikely(is_vm_hugetlb_page(vma))) {
L
Linus Torvalds 已提交
841
				unmap_hugepage_range(vma, start, end);
842 843 844 845 846 847 848 849 850 851
				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
852 853 854 855 856 857 858
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
				(i_mmap_lock && need_lockbreak(i_mmap_lock))) {
				if (i_mmap_lock) {
859
					*tlbp = NULL;
L
Linus Torvalds 已提交
860 861 862 863 864
					goto out;
				}
				cond_resched();
			}

865
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
866
			tlb_start_valid = 0;
867
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
868 869 870
		}
	}
out:
871
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
872 873 874 875 876 877 878 879 880
}

/**
 * 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
 */
881
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
882 883 884 885 886 887 888 889 890
		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);
891
	update_hiwater_rss(mm);
892 893 894
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
895
	return end;
L
Linus Torvalds 已提交
896 897 898 899 900
}

/*
 * Do a quick page-table lookup for a single page.
 */
901
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
902
			unsigned int flags)
L
Linus Torvalds 已提交
903 904 905 906 907
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
908
	spinlock_t *ptl;
L
Linus Torvalds 已提交
909
	struct page *page;
910
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
911

912 913 914 915 916
	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
917

918
	page = NULL;
L
Linus Torvalds 已提交
919 920
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
921
		goto no_page_table;
L
Linus Torvalds 已提交
922 923 924

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
925
		goto no_page_table;
L
Linus Torvalds 已提交
926 927 928
	
	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
929 930 931 932 933
		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
934
		goto out;
935
	}
L
Linus Torvalds 已提交
936

937
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
938 939 940 941
	if (!ptep)
		goto out;

	pte = *ptep;
942 943 944 945
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
946 947
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
948
		goto unlock;
L
Linus Torvalds 已提交
949

950 951 952 953 954 955 956 957 958 959
	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
960
out:
961
	return page;
L
Linus Torvalds 已提交
962

963 964 965 966 967 968 969 970 971 972 973 974
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) {
		page = ZERO_PAGE(address);
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
975 976 977 978 979 980 981
}

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;
982
	unsigned int vm_flags;
L
Linus Torvalds 已提交
983 984 985 986 987

	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
988 989
	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
990 991 992
	i = 0;

	do {
993 994
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013

		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);
1014 1015
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1016
			pte = pte_offset_map(pmd, pg);
1017 1018 1019 1020
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1021
			if (pages) {
1022
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1023 1024 1025
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1026 1027 1028 1029 1030 1031 1032 1033 1034 1035
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1036
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1037
				|| !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1038 1039 1040 1041 1042 1043 1044
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
						&start, &len, i);
			continue;
		}
1045 1046 1047 1048 1049

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
		if (!write && !(vma->vm_flags & VM_LOCKED) &&
1050 1051
		    (!vma->vm_ops || (!vma->vm_ops->nopage &&
					!vma->vm_ops->fault)))
1052 1053
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1054
		do {
1055
			struct page *page;
L
Linus Torvalds 已提交
1056

1057 1058 1059 1060 1061 1062 1063 1064
			/*
			 * 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;

1065 1066
			if (write)
				foll_flags |= FOLL_WRITE;
1067

1068
			cond_resched();
1069
			while (!(page = follow_page(vma, start, foll_flags))) {
1070 1071 1072
				int ret;
				ret = __handle_mm_fault(mm, vma, start,
						foll_flags & FOLL_WRITE);
1073 1074 1075 1076 1077 1078 1079
				/*
				 * 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.
				 */
				if (ret & VM_FAULT_WRITE)
1080
					foll_flags &= ~FOLL_WRITE;
1081 1082
				
				switch (ret & ~VM_FAULT_WRITE) {
L
Linus Torvalds 已提交
1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095
				case VM_FAULT_MINOR:
					tsk->min_flt++;
					break;
				case VM_FAULT_MAJOR:
					tsk->maj_flt++;
					break;
				case VM_FAULT_SIGBUS:
					return i ? i : -EFAULT;
				case VM_FAULT_OOM:
					return i ? i : -ENOMEM;
				default:
					BUG();
				}
1096
				cond_resched();
L
Linus Torvalds 已提交
1097 1098
			}
			if (pages) {
1099
				pages[i] = page;
1100

1101
				flush_anon_page(vma, page, start);
1102
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1103 1104 1105 1106 1107 1108
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1109 1110
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1111 1112 1113 1114 1115 1116 1117 1118
	return i;
}
EXPORT_SYMBOL(get_user_pages);

static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pte_t *pte;
H
Hugh Dickins 已提交
1119
	spinlock_t *ptl;
1120
	int err = 0;
L
Linus Torvalds 已提交
1121

H
Hugh Dickins 已提交
1122
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1123
	if (!pte)
1124
		return -EAGAIN;
1125
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1126
	do {
N
Nick Piggin 已提交
1127 1128
		struct page *page = ZERO_PAGE(addr);
		pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1129 1130 1131 1132 1133 1134

		if (unlikely(!pte_none(*pte))) {
			err = -EEXIST;
			pte++;
			break;
		}
N
Nick Piggin 已提交
1135 1136 1137
		page_cache_get(page);
		page_add_file_rmap(page);
		inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
1138 1139
		set_pte_at(mm, addr, pte, zero_pte);
	} while (pte++, addr += PAGE_SIZE, addr != end);
1140
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1141
	pte_unmap_unlock(pte - 1, ptl);
1142
	return err;
L
Linus Torvalds 已提交
1143 1144 1145 1146 1147 1148 1149
}

static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pmd_t *pmd;
	unsigned long next;
1150
	int err;
L
Linus Torvalds 已提交
1151 1152 1153

	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
1154
		return -EAGAIN;
L
Linus Torvalds 已提交
1155 1156
	do {
		next = pmd_addr_end(addr, end);
1157 1158 1159
		err = zeromap_pte_range(mm, pmd, addr, next, prot);
		if (err)
			break;
L
Linus Torvalds 已提交
1160
	} while (pmd++, addr = next, addr != end);
1161
	return err;
L
Linus Torvalds 已提交
1162 1163 1164 1165 1166 1167 1168
}

static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pud_t *pud;
	unsigned long next;
1169
	int err;
L
Linus Torvalds 已提交
1170 1171 1172

	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
1173
		return -EAGAIN;
L
Linus Torvalds 已提交
1174 1175
	do {
		next = pud_addr_end(addr, end);
1176 1177 1178
		err = zeromap_pmd_range(mm, pud, addr, next, prot);
		if (err)
			break;
L
Linus Torvalds 已提交
1179
	} while (pud++, addr = next, addr != end);
1180
	return err;
L
Linus Torvalds 已提交
1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203
}

int zeromap_page_range(struct vm_area_struct *vma,
			unsigned long addr, unsigned long size, pgprot_t prot)
{
	pgd_t *pgd;
	unsigned long next;
	unsigned long end = addr + size;
	struct mm_struct *mm = vma->vm_mm;
	int err;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	flush_cache_range(vma, addr, end);
	do {
		next = pgd_addr_end(addr, end);
		err = zeromap_pud_range(mm, pgd, addr, next, prot);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
	return err;
}

1204
pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1205 1206 1207 1208
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1209
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1210 1211 1212 1213 1214 1215
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1216 1217 1218 1219 1220 1221 1222 1223 1224 1225
/*
 * 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.
 */
static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
{
	int retval;
1226
	pte_t *pte;
1227 1228 1229
	spinlock_t *ptl;  

	retval = -EINVAL;
1230
	if (PageAnon(page))
1231 1232 1233
		goto out;
	retval = -ENOMEM;
	flush_dcache_page(page);
1234
	pte = get_locked_pte(mm, addr, &ptl);
1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253
	if (!pte)
		goto out;
	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;
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1254 1255 1256 1257 1258 1259
/**
 * 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
 *
1260 1261 1262 1263 1264 1265
 * 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
1266
 * (see split_page()).
1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281
 *
 * 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.
 */
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1282
	vma->vm_flags |= VM_INSERTPAGE;
1283 1284
	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
1285
EXPORT_SYMBOL(vm_insert_page);
1286

N
Nick Piggin 已提交
1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 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 1330 1331
/**
 * 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,
		unsigned long pfn)
{
	struct mm_struct *mm = vma->vm_mm;
	int retval;
	pte_t *pte, entry;
	spinlock_t *ptl;

	BUG_ON(!(vma->vm_flags & VM_PFNMAP));
	BUG_ON(is_cow_mapping(vma->vm_flags));

	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 = pfn_pte(pfn, vma->vm_page_prot);
	set_pte_at(mm, addr, pte, entry);
	update_mmu_cache(vma, addr, entry);

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

out:
	return retval;
}
EXPORT_SYMBOL(vm_insert_pfn);

L
Linus Torvalds 已提交
1332 1333 1334 1335 1336 1337 1338 1339 1340 1341
/*
 * 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
1342
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1343

H
Hugh Dickins 已提交
1344
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1345 1346
	if (!pte)
		return -ENOMEM;
1347
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1348 1349
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1350
		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
L
Linus Torvalds 已提交
1351 1352
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1353
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1354
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397
	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;
}

1398 1399 1400 1401 1402 1403 1404 1405 1406 1407
/**
 * 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
1408 1409 1410 1411 1412
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;
1413
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1414 1415 1416 1417 1418 1419 1420 1421
	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
1422 1423 1424 1425 1426
	 *   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.
1427 1428 1429
	 *   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
1430 1431 1432 1433
	 *
	 * 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
1434
	 */
1435
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1436
		if (addr != vma->vm_start || end != vma->vm_end)
1437
			return -EINVAL;
L
Linus Torvalds 已提交
1438 1439 1440
		vma->vm_pgoff = pfn;
	}

1441
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457

	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);

1458 1459 1460 1461 1462 1463 1464
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;
	struct page *pmd_page;
1465
	spinlock_t *uninitialized_var(ptl);
1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551

	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));

	pmd_page = pmd_page(*pmd);

	do {
		err = fn(pte, pmd_page, addr, data);
		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);

1552 1553 1554 1555 1556 1557 1558 1559 1560
/*
 * 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
1561
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1562 1563 1564 1565 1566
				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
1567 1568
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1569
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1570
		spin_unlock(ptl);
1571 1572 1573 1574 1575 1576
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589
/*
 * 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;
}

1590
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1591 1592 1593 1594 1595 1596 1597 1598 1599
{
	/*
	 * 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
1600 1601 1602 1603 1604 1605 1606 1607 1608
		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))
1609 1610
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1611
		flush_dcache_page(dst);
1612
		return;
1613

1614
	}
1615
	copy_user_highpage(dst, src, va, vma);
1616 1617
}

L
Linus Torvalds 已提交
1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631
/*
 * 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.
 *
1632 1633 1634
 * 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
1635
 */
1636 1637
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1638
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1639
{
1640
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1641
	pte_t entry;
1642 1643
	int reuse = 0, ret = VM_FAULT_MINOR;
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1644

1645 1646 1647
	old_page = vm_normal_page(vma, address, orig_pte);
	if (!old_page)
		goto gotten;
L
Linus Torvalds 已提交
1648

1649
	/*
P
Peter Zijlstra 已提交
1650 1651
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1652
	 */
P
Peter Zijlstra 已提交
1653 1654 1655 1656 1657 1658
	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)) ==
1659
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1660 1661 1662 1663 1664
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687
		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);
1688
			page_cache_release(old_page);
1689 1690
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
L
Linus Torvalds 已提交
1691
		}
1692 1693
		dirty_page = old_page;
		get_page(dirty_page);
1694 1695 1696 1697 1698 1699 1700
		reuse = 1;
	}

	if (reuse) {
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1701 1702 1703 1704
		if (ptep_set_access_flags(vma, address, page_table, entry,1)) {
			update_mmu_cache(vma, address, entry);
			lazy_mmu_prot_update(entry);
		}
1705 1706
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1707 1708 1709 1710 1711
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1712
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1713
gotten:
1714
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1715 1716

	if (unlikely(anon_vma_prepare(vma)))
1717
		goto oom;
1718
	if (old_page == ZERO_PAGE(address)) {
1719
		new_page = alloc_zeroed_user_highpage_movable(vma, address);
L
Linus Torvalds 已提交
1720
		if (!new_page)
1721
			goto oom;
L
Linus Torvalds 已提交
1722
	} else {
1723
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
1724
		if (!new_page)
1725
			goto oom;
1726
		cow_user_page(new_page, old_page, address, vma);
L
Linus Torvalds 已提交
1727
	}
1728

L
Linus Torvalds 已提交
1729 1730 1731
	/*
	 * Re-check the pte - we dropped the lock
	 */
1732
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1733
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1734
		if (old_page) {
N
Nick Piggin 已提交
1735
			page_remove_rmap(old_page, vma);
H
Hugh Dickins 已提交
1736 1737 1738 1739 1740
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1741
			inc_mm_counter(mm, anon_rss);
1742
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1743 1744
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1745
		lazy_mmu_prot_update(entry);
1746 1747 1748 1749 1750 1751 1752 1753
		/*
		 * 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);
1754
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1755
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1756
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1757 1758 1759

		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1760
		ret |= VM_FAULT_WRITE;
L
Linus Torvalds 已提交
1761
	}
H
Hugh Dickins 已提交
1762 1763 1764 1765
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1766
unlock:
1767
	pte_unmap_unlock(page_table, ptl);
1768
	if (dirty_page) {
P
Peter Zijlstra 已提交
1769
		set_page_dirty_balance(dirty_page);
1770 1771
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1772
	return ret;
1773
oom:
H
Hugh Dickins 已提交
1774 1775
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1776
	return VM_FAULT_OOM;
1777 1778 1779 1780

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807
}

/*
 * 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
1808
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834
 * 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;

1835 1836 1837 1838 1839 1840 1841
	/*
	 * files that support invalidating or truncating portions of the
	 * file from under mmaped areas must set the VM_CAN_INVALIDATE flag, and
	 * have their .nopage function return the page locked.
	 */
	BUG_ON(!(vma->vm_flags & VM_CAN_INVALIDATE));

L
Linus Torvalds 已提交
1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852
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;
		}
	}

1853 1854
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
L
Linus Torvalds 已提交
1855 1856 1857
	need_break = need_resched() ||
			need_lockbreak(details->i_mmap_lock);

1858
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1859 1860 1861 1862 1863 1864
		/* 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 */
1865
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 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 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931
		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;
	}
}

/**
1932
 * 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
1933
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969
 * @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);

1970
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986
	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);

1987 1988 1989 1990
/**
 * 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
1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
 *
 * 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)
{
	struct address_space *mapping = inode->i_mapping;
	unsigned long limit;

	if (inode->i_size < offset)
		goto do_expand;
	/*
	 * truncation of in-use swapfiles is disallowed - it would cause
	 * subsequent swapout to scribble on the now-freed blocks.
	 */
	if (IS_SWAPFILE(inode))
		goto out_busy;
	i_size_write(inode, offset);
2010 2011 2012 2013 2014 2015 2016 2017 2018

	/*
	 * 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.
	 */
L
Linus Torvalds 已提交
2019 2020
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	truncate_inode_pages(mapping, offset);
2021
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
L
Linus Torvalds 已提交
2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044
	goto out_truncate;

do_expand:
	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);

out_truncate:
	if (inode->i_op && inode->i_op->truncate)
		inode->i_op->truncate(inode);
	return 0;
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
out_busy:
	return -ETXTBSY;
}
EXPORT_SYMBOL(vmtruncate);

2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056
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;

2057
	mutex_lock(&inode->i_mutex);
2058 2059 2060
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2061
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2062 2063
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2064
	mutex_unlock(&inode->i_mutex);
2065 2066 2067 2068

	return 0;
}

2069 2070 2071 2072 2073 2074
/**
 * swapin_readahead - swap in pages in hope we need them soon
 * @entry: swap entry of this memory
 * @addr: address to start
 * @vma: user vma this addresses belong to
 *
L
Linus Torvalds 已提交
2075 2076 2077
 * Primitive swap readahead code. We simply read an aligned block of
 * (1 << page_cluster) entries in the swap area. This method is chosen
 * because it doesn't cost us any seek time.  We also make sure to queue
2078
 * the 'original' request together with the readahead ones...
L
Linus Torvalds 已提交
2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130
 *
 * This has been extended to use the NUMA policies from the mm triggering
 * the readahead.
 *
 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
 */
void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
{
#ifdef CONFIG_NUMA
	struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
#endif
	int i, num;
	struct page *new_page;
	unsigned long offset;

	/*
	 * Get the number of handles we should do readahead io to.
	 */
	num = valid_swaphandles(entry, &offset);
	for (i = 0; i < num; offset++, i++) {
		/* Ok, do the async read-ahead now */
		new_page = read_swap_cache_async(swp_entry(swp_type(entry),
							   offset), vma, addr);
		if (!new_page)
			break;
		page_cache_release(new_page);
#ifdef CONFIG_NUMA
		/*
		 * Find the next applicable VMA for the NUMA policy.
		 */
		addr += PAGE_SIZE;
		if (addr == 0)
			vma = NULL;
		if (vma) {
			if (addr >= vma->vm_end) {
				vma = next_vma;
				next_vma = vma ? vma->vm_next : NULL;
			}
			if (vma && addr < vma->vm_start)
				vma = NULL;
		} else {
			if (next_vma && addr >= next_vma->vm_start) {
				vma = next_vma;
				next_vma = vma->vm_next;
			}
		}
#endif
	}
	lru_add_drain();	/* Push any new pages onto the LRU now */
}

/*
2131 2132 2133
 * 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
2134
 */
2135 2136 2137
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
2138
{
2139
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2140
	struct page *page;
2141
	swp_entry_t entry;
L
Linus Torvalds 已提交
2142 2143 2144
	pte_t pte;
	int ret = VM_FAULT_MINOR;

H
Hugh Dickins 已提交
2145
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2146
		goto out;
2147 2148

	entry = pte_to_swp_entry(orig_pte);
2149 2150 2151 2152
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2153
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2154 2155
	page = lookup_swap_cache(entry);
	if (!page) {
2156
		grab_swap_token(); /* Contend for token _before_ read-in */
L
Linus Torvalds 已提交
2157 2158 2159 2160
 		swapin_readahead(entry, address, vma);
 		page = read_swap_cache_async(entry, vma, address);
		if (!page) {
			/*
2161 2162
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2163
			 */
2164
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2165 2166
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2167
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2168
			goto unlock;
L
Linus Torvalds 已提交
2169 2170 2171 2172
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2173
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2174 2175
	}

2176
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2177 2178 2179 2180
	mark_page_accessed(page);
	lock_page(page);

	/*
2181
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2182
	 */
2183
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2184
	if (unlikely(!pte_same(*page_table, orig_pte)))
2185 2186 2187 2188 2189
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2190 2191 2192 2193
	}

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

2194
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2195 2196 2197 2198 2199 2200 2201 2202 2203 2204
	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);

2205 2206 2207 2208 2209
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2210 2211
	if (write_access) {
		if (do_wp_page(mm, vma, address,
2212
				page_table, pmd, ptl, pte) == VM_FAULT_OOM)
L
Linus Torvalds 已提交
2213 2214 2215 2216 2217 2218
			ret = VM_FAULT_OOM;
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2219
unlock:
2220
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2221 2222
out:
	return ret;
2223
out_nomap:
2224
	pte_unmap_unlock(page_table, ptl);
2225 2226
	unlock_page(page);
	page_cache_release(page);
2227
	return ret;
L
Linus Torvalds 已提交
2228 2229 2230
}

/*
2231 2232 2233
 * 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
2234
 */
2235 2236 2237
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
2238
{
2239 2240
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2241 2242
	pte_t entry;

2243
	if (write_access) {
L
Linus Torvalds 已提交
2244 2245 2246 2247
		/* Allocate our own private page. */
		pte_unmap(page_table);

		if (unlikely(anon_vma_prepare(vma)))
2248
			goto oom;
2249
		page = alloc_zeroed_user_highpage_movable(vma, address);
L
Linus Torvalds 已提交
2250
		if (!page)
2251
			goto oom;
L
Linus Torvalds 已提交
2252

2253 2254
		entry = mk_pte(page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2255 2256 2257 2258 2259

		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
		if (!pte_none(*page_table))
			goto release;
		inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2260
		lru_cache_add_active(page);
N
Nick Piggin 已提交
2261
		page_add_new_anon_rmap(page, vma, address);
N
Nick Piggin 已提交
2262
	} else {
2263 2264 2265 2266 2267
		/* Map the ZERO_PAGE - vm_page_prot is readonly */
		page = ZERO_PAGE(address);
		page_cache_get(page);
		entry = mk_pte(page, vma->vm_page_prot);

H
Hugh Dickins 已提交
2268
		ptl = pte_lockptr(mm, pmd);
2269 2270 2271
		spin_lock(ptl);
		if (!pte_none(*page_table))
			goto release;
N
Nick Piggin 已提交
2272 2273
		inc_mm_counter(mm, file_rss);
		page_add_file_rmap(page);
L
Linus Torvalds 已提交
2274 2275
	}

2276
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2277 2278

	/* No need to invalidate - it was non-present before */
2279
	update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2280
	lazy_mmu_prot_update(entry);
2281
unlock:
2282
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2283
	return VM_FAULT_MINOR;
2284 2285 2286
release:
	page_cache_release(page);
	goto unlock;
2287
oom:
L
Linus Torvalds 已提交
2288 2289 2290 2291
	return VM_FAULT_OOM;
}

/*
2292
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2293
 * tries to share with existing pages, but makes a separate copy if
2294 2295
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2296 2297 2298 2299
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2300 2301 2302
 * 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
2303
 */
2304
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2305
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2306
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2307
{
2308
	spinlock_t *ptl;
2309
	struct page *page, *faulted_page;
L
Linus Torvalds 已提交
2310 2311
	pte_t entry;
	int anon = 0;
2312
	struct page *dirty_page = NULL;
2313 2314 2315 2316 2317
	struct fault_data fdata;

	fdata.address = address & PAGE_MASK;
	fdata.pgoff = pgoff;
	fdata.flags = flags;
L
Linus Torvalds 已提交
2318 2319

	pte_unmap(page_table);
2320 2321
	BUG_ON(vma->vm_flags & VM_PFNMAP);

2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338
	if (likely(vma->vm_ops->fault)) {
		fdata.type = -1;
		faulted_page = vma->vm_ops->fault(vma, &fdata);
		WARN_ON(fdata.type == -1);
		if (unlikely(!faulted_page))
			return fdata.type;
	} else {
		/* Legacy ->nopage path */
		fdata.type = VM_FAULT_MINOR;
		faulted_page = vma->vm_ops->nopage(vma, address & PAGE_MASK,
								&fdata.type);
		/* no page was available -- either SIGBUS or OOM */
		if (unlikely(faulted_page == NOPAGE_SIGBUS))
			return VM_FAULT_SIGBUS;
		else if (unlikely(faulted_page == NOPAGE_OOM))
			return VM_FAULT_OOM;
	}
L
Linus Torvalds 已提交
2339

2340
	/*
2341
	 * For consistency in subsequent calls, make the faulted_page always
2342 2343 2344
	 * locked.
	 */
	if (unlikely(!(vma->vm_flags & VM_CAN_INVALIDATE)))
2345 2346 2347
		lock_page(faulted_page);
	else
		BUG_ON(!PageLocked(faulted_page));
2348

L
Linus Torvalds 已提交
2349 2350 2351
	/*
	 * Should we do an early C-O-W break?
	 */
2352 2353
	page = faulted_page;
	if (flags & FAULT_FLAG_WRITE) {
2354
		if (!(vma->vm_flags & VM_SHARED)) {
2355
			anon = 1;
2356
			if (unlikely(anon_vma_prepare(vma))) {
2357 2358
				fdata.type = VM_FAULT_OOM;
				goto out;
2359 2360 2361
			}
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
			if (!page) {
2362 2363
				fdata.type = VM_FAULT_OOM;
				goto out;
2364
			}
2365
			copy_user_highpage(page, faulted_page, address, vma);
2366
		} else {
2367 2368
			/*
			 * If the page will be shareable, see if the backing
2369
			 * address space wants to know that the page is about
2370 2371
			 * to become writable
			 */
2372
			if (vma->vm_ops->page_mkwrite &&
2373
			    vma->vm_ops->page_mkwrite(vma, page) < 0) {
2374 2375 2376
				fdata.type = VM_FAULT_SIGBUS;
				anon = 1; /* no anon but release faulted_page */
				goto out;
2377 2378
			}
		}
2379

L
Linus Torvalds 已提交
2380 2381
	}

2382
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394

	/*
	 * 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... */
2395
	if (likely(pte_same(*page_table, orig_pte))) {
2396 2397
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2398
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2399 2400 2401
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2402 2403 2404
                        inc_mm_counter(mm, anon_rss);
                        lru_cache_add_active(page);
                        page_add_new_anon_rmap(page, vma, address);
2405
		} else {
2406
			inc_mm_counter(mm, file_rss);
2407
			page_add_file_rmap(page);
2408
			if (flags & FAULT_FLAG_WRITE) {
2409
				dirty_page = page;
2410 2411
				get_page(dirty_page);
			}
2412
		}
2413 2414 2415 2416

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(entry);
L
Linus Torvalds 已提交
2417
	} else {
2418 2419 2420
		if (anon)
			page_cache_release(page);
		else
2421
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2422 2423
	}

2424
	pte_unmap_unlock(page_table, ptl);
2425 2426

out:
2427
	unlock_page(faulted_page);
2428
	if (anon)
2429
		page_cache_release(faulted_page);
2430
	else if (dirty_page) {
P
Peter Zijlstra 已提交
2431
		set_page_dirty_balance(dirty_page);
2432 2433
		put_page(dirty_page);
	}
2434

2435 2436
	return fdata.type;
}
2437

2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456
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)
			- vma->vm_start) >> PAGE_CACHE_SHIFT) + vma->vm_pgoff;
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

	return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte);
}

static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pgoff_t pgoff, pte_t orig_pte)
{
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);

	return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2457 2458
}

J
Jes Sorensen 已提交
2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488
/*
 * 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;
	int ret = VM_FAULT_MINOR;

	pte_unmap(page_table);
	BUG_ON(!(vma->vm_flags & VM_PFNMAP));
	BUG_ON(is_cow_mapping(vma->vm_flags));

	pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
2489
	if (unlikely(pfn == NOPFN_OOM))
J
Jes Sorensen 已提交
2490
		return VM_FAULT_OOM;
2491
	else if (unlikely(pfn == NOPFN_SIGBUS))
J
Jes Sorensen 已提交
2492
		return VM_FAULT_SIGBUS;
2493 2494
	else if (unlikely(pfn == NOPFN_REFAULT))
		return VM_FAULT_MINOR;
J
Jes Sorensen 已提交
2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508

	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);
	return ret;
}

L
Linus Torvalds 已提交
2509 2510 2511 2512
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2513 2514 2515 2516
 *
 * 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
2517
 */
2518 2519 2520
static int do_file_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
2521
{
2522
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2523 2524
	int err;

H
Hugh Dickins 已提交
2525
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2526
		return VM_FAULT_MINOR;
L
Linus Torvalds 已提交
2527

2528 2529 2530 2531
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2532
		print_bad_pte(vma, orig_pte, address);
2533 2534 2535 2536
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2537 2538 2539 2540 2541 2542

	if (vma->vm_ops && vma->vm_ops->fault)
		return do_nonlinear_fault(mm, vma, address, page_table, pmd,
					write_access, pgoff, orig_pte);

	/* We can then assume vm->vm_ops && vma->vm_ops->populate */
2543 2544
	err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
					vma->vm_page_prot, pgoff, 0);
L
Linus Torvalds 已提交
2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560
	if (err == -ENOMEM)
		return VM_FAULT_OOM;
	if (err)
		return VM_FAULT_SIGBUS;
	return VM_FAULT_MAJOR;
}

/*
 * 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
2561 2562 2563
 * 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
2564 2565
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2566 2567
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2568 2569
{
	pte_t entry;
2570
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2571

2572
	entry = *pte;
L
Linus Torvalds 已提交
2573
	if (!pte_present(entry)) {
2574
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2575
			if (vma->vm_ops) {
2576 2577 2578
				if (vma->vm_ops->fault || vma->vm_ops->nopage)
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2579 2580 2581 2582 2583 2584
				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);
2585
		}
L
Linus Torvalds 已提交
2586
		if (pte_file(entry))
2587 2588 2589 2590
			return do_file_page(mm, vma, address,
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2591 2592
	}

H
Hugh Dickins 已提交
2593
	ptl = pte_lockptr(mm, pmd);
2594 2595 2596
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2597 2598
	if (write_access) {
		if (!pte_write(entry))
2599 2600
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2601 2602 2603
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2604
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(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);
	}
2617 2618
unlock:
	pte_unmap_unlock(pte, ptl);
L
Linus Torvalds 已提交
2619 2620 2621 2622 2623 2624
	return VM_FAULT_MINOR;
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
2625
int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2626 2627 2628 2629 2630 2631 2632 2633 2634
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2635
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2636

2637 2638
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2639 2640 2641 2642

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2643
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2644 2645
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2646
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2647 2648
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2649
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2650

H
Hugh Dickins 已提交
2651
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2652 2653
}

2654 2655
EXPORT_SYMBOL_GPL(__handle_mm_fault);

L
Linus Torvalds 已提交
2656 2657 2658
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2659
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2660
 */
2661
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2662
{
H
Hugh Dickins 已提交
2663 2664
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2665
		return -ENOMEM;
L
Linus Torvalds 已提交
2666

H
Hugh Dickins 已提交
2667
	spin_lock(&mm->page_table_lock);
2668
	if (pgd_present(*pgd))		/* Another has populated it */
L
Linus Torvalds 已提交
2669
		pud_free(new);
2670 2671
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2672
	spin_unlock(&mm->page_table_lock);
2673
	return 0;
L
Linus Torvalds 已提交
2674 2675 2676 2677 2678 2679
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2680
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2681
 */
2682
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2683
{
H
Hugh Dickins 已提交
2684 2685
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2686
		return -ENOMEM;
L
Linus Torvalds 已提交
2687

H
Hugh Dickins 已提交
2688
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2689
#ifndef __ARCH_HAS_4LEVEL_HACK
2690
	if (pud_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2691
		pmd_free(new);
2692 2693
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2694
#else
2695
	if (pgd_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2696
		pmd_free(new);
2697 2698
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2699
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2700
	spin_unlock(&mm->page_table_lock);
2701
	return 0;
2702
}
L
Linus Torvalds 已提交
2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713
#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;
2714 2715
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2716
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
	if (ret < 0)
		return ret;
	return ret == len ? 0 : -1;
}

/* 
 * Map a vmalloc()-space virtual address to the physical page.
 */
struct page * vmalloc_to_page(void * vmalloc_addr)
{
	unsigned long addr = (unsigned long) vmalloc_addr;
	struct page *page = NULL;
	pgd_t *pgd = pgd_offset_k(addr);
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
  
	if (!pgd_none(*pgd)) {
		pud = pud_offset(pgd, addr);
		if (!pud_none(*pud)) {
			pmd = pmd_offset(pud, addr);
			if (!pmd_none(*pmd)) {
				ptep = pte_offset_map(pmd, addr);
				pte = *ptep;
				if (pte_present(pte))
					page = pte_page(pte);
				pte_unmap(ptep);
			}
		}
	}
	return page;
}

EXPORT_SYMBOL(vmalloc_to_page);

/*
 * Map a vmalloc()-space virtual address to the physical page frame number.
 */
unsigned long vmalloc_to_pfn(void * vmalloc_addr)
{
	return page_to_pfn(vmalloc_to_page(vmalloc_addr));
}

EXPORT_SYMBOL(vmalloc_to_pfn);

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2767
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2768 2769 2770 2771 2772 2773

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
2774 2775
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2776 2777 2778 2779 2780 2781 2782
	/*
	 * 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
2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806
	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 */
2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 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 2859

/*
 * 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);
	/* ignore errors, just check how much was sucessfully transfered */
	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;
}