memory.c 71.8 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);
262 263 264
}

void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
265
		unsigned long floor, unsigned long ceiling)
266 267 268 269 270
{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

271 272 273 274 275 276
		/*
		 * Hide vma from rmap and vmtruncate before freeing pgtables
		 */
		anon_vma_unlink(vma);
		unlink_file_vma(vma);

277
		if (is_vm_hugetlb_page(vma)) {
278
			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
279
				floor, next? next->vm_start: ceiling);
280 281 282 283 284
		} else {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
285
			       && !is_vm_hugetlb_page(next)) {
286 287
				vma = next;
				next = vma->vm_next;
288 289
				anon_vma_unlink(vma);
				unlink_file_vma(vma);
290 291 292 293
			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
294 295
		vma = next;
	}
L
Linus Torvalds 已提交
296 297
}

298
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
299
{
H
Hugh Dickins 已提交
300
	struct page *new = pte_alloc_one(mm, address);
301 302 303
	if (!new)
		return -ENOMEM;

H
Hugh Dickins 已提交
304
	pte_lock_init(new);
H
Hugh Dickins 已提交
305
	spin_lock(&mm->page_table_lock);
H
Hugh Dickins 已提交
306 307
	if (pmd_present(*pmd)) {	/* Another has populated it */
		pte_lock_deinit(new);
308
		pte_free(new);
H
Hugh Dickins 已提交
309
	} else {
L
Linus Torvalds 已提交
310
		mm->nr_ptes++;
311
		inc_zone_page_state(new, NR_PAGETABLE);
L
Linus Torvalds 已提交
312 313
		pmd_populate(mm, pmd, new);
	}
H
Hugh Dickins 已提交
314
	spin_unlock(&mm->page_table_lock);
315
	return 0;
L
Linus Torvalds 已提交
316 317
}

318
int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
319
{
320 321 322 323 324 325 326 327 328 329 330
	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
331 332
}

333 334 335 336 337 338 339 340
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
341
/*
342 343 344
 * 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
345 346 347 348 349 350 351 352 353 354 355 356 357
 *
 * 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();
}

358 359 360 361 362
static inline int is_cow_mapping(unsigned int flags)
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

H
Hugh Dickins 已提交
363
/*
364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381
 * 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
382
 */
383
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
H
Hugh Dickins 已提交
384
{
385 386
	unsigned long pfn = pte_pfn(pte);

N
Nick Piggin 已提交
387
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
388 389 390
		unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
		if (pfn == vma->vm_pgoff + off)
			return NULL;
391
		if (!is_cow_mapping(vma->vm_flags))
L
Linus Torvalds 已提交
392
			return NULL;
393 394
	}

395
#ifdef CONFIG_DEBUG_VM
396 397 398 399 400 401
	/*
	 * 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.
	 */
402 403 404 405
	if (unlikely(!pfn_valid(pfn))) {
		print_bad_pte(vma, pte, addr);
		return NULL;
	}
406
#endif
407 408 409 410 411 412 413 414 415

	/*
	 * 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
416 417
}

L
Linus Torvalds 已提交
418 419 420 421 422 423
/*
 * 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
424
static inline void
L
Linus Torvalds 已提交
425
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
426
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
427
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
428
{
N
Nick Piggin 已提交
429
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
430 431 432 433 434 435
	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)) {
436 437 438
			swp_entry_t entry = pte_to_swp_entry(pte);

			swap_duplicate(entry);
L
Linus Torvalds 已提交
439 440 441
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
442 443 444
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
445 446
				spin_unlock(&mmlist_lock);
			}
447 448 449 450 451 452 453 454 455 456
			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
457
		}
458
		goto out_set_pte;
L
Linus Torvalds 已提交
459 460 461 462 463 464
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
465
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
466
		ptep_set_wrprotect(src_mm, addr, src_pte);
467
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
468 469 470 471 472 473 474 475 476
	}

	/*
	 * 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);
477 478 479 480

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
N
Nick Piggin 已提交
481
		page_dup_rmap(page, vma, addr);
482 483
		rss[!!PageAnon(page)]++;
	}
484 485 486

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
L
Linus Torvalds 已提交
487 488 489 490 491 492 493
}

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
494
	spinlock_t *src_ptl, *dst_ptl;
495
	int progress = 0;
H
Hugh Dickins 已提交
496
	int rss[2];
L
Linus Torvalds 已提交
497 498

again:
499
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
500
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
501 502 503
	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
504
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
505
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
506
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
507 508 509 510 511 512

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
513 514 515
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
516
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
517 518
				break;
		}
L
Linus Torvalds 已提交
519 520 521 522
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
523
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
524 525 526
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

527
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
528
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
529
	pte_unmap_nested(src_pte - 1);
530
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
531 532
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
L
Linus Torvalds 已提交
533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589
	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;

590 591 592 593 594 595
	/*
	 * 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.
	 */
596
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
597 598 599 600
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616
	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;
}

617
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
618
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
619
				unsigned long addr, unsigned long end,
620
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
621
{
N
Nick Piggin 已提交
622
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
623
	pte_t *pte;
624
	spinlock_t *ptl;
625 626
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
627

628
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
629
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
630 631
	do {
		pte_t ptent = *pte;
632 633
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
634
			continue;
635
		}
636 637 638

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
639
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
640
			struct page *page;
641

642
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660
			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
661
			ptent = ptep_get_and_clear_full(mm, addr, pte,
662
							tlb->fullmm);
L
Linus Torvalds 已提交
663 664 665 666 667 668
			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
669
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
670 671
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
672
				anon_rss--;
673 674 675 676
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
677
					SetPageReferenced(page);
H
Hugh Dickins 已提交
678
				file_rss--;
679
			}
N
Nick Piggin 已提交
680
			page_remove_rmap(page, vma);
L
Linus Torvalds 已提交
681 682 683 684 685 686 687 688 689 690 691
			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));
692
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
693
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
694

H
Hugh Dickins 已提交
695
	add_mm_rss(mm, file_rss, anon_rss);
696
	arch_leave_lazy_mmu_mode();
697
	pte_unmap_unlock(pte - 1, ptl);
698 699

	return addr;
L
Linus Torvalds 已提交
700 701
}

702
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
703
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
704
				unsigned long addr, unsigned long end,
705
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
706 707 708 709 710 711 712
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
713 714
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
715
			continue;
716 717 718 719 720 721
		}
		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
722 723
}

724
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
725
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
726
				unsigned long addr, unsigned long end,
727
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
728 729 730 731 732 733 734
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
735 736
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
737
			continue;
738 739 740 741 742 743
		}
		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
744 745
}

746 747
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
748
				unsigned long addr, unsigned long end,
749
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
750 751 752 753 754 755 756 757 758 759 760 761
{
	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);
762 763
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
764
			continue;
765 766 767 768
		}
		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
769
	tlb_end_vma(tlb, vma);
770 771

	return addr;
L
Linus Torvalds 已提交
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789
}

#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
 *
790
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
791
 *
792
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
793
 *
794 795
 * 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
796 797 798 799 800 801 802 803 804 805 806
 * 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.
 */
807
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
808 809 810 811
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
812
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
813 814
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
815
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
816
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
817
	int fullmm = (*tlbp)->fullmm;
L
Linus Torvalds 已提交
818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837

	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;
			}

838
			if (unlikely(is_vm_hugetlb_page(vma))) {
L
Linus Torvalds 已提交
839
				unmap_hugepage_range(vma, start, end);
840 841 842 843 844 845 846 847 848 849
				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
850 851 852 853 854
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
855
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
856
				if (i_mmap_lock) {
857
					*tlbp = NULL;
L
Linus Torvalds 已提交
858 859 860 861 862
					goto out;
				}
				cond_resched();
			}

863
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
864
			tlb_start_valid = 0;
865
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
866 867 868
		}
	}
out:
869
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
870 871 872 873 874 875 876 877 878
}

/**
 * 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
 */
879
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
880 881 882 883 884 885 886 887 888
		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);
889
	update_hiwater_rss(mm);
890 891 892
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
893
	return end;
L
Linus Torvalds 已提交
894 895 896 897 898
}

/*
 * Do a quick page-table lookup for a single page.
 */
899
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
900
			unsigned int flags)
L
Linus Torvalds 已提交
901 902 903 904 905
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
906
	spinlock_t *ptl;
L
Linus Torvalds 已提交
907
	struct page *page;
908
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
909

910 911 912 913 914
	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
915

916
	page = NULL;
L
Linus Torvalds 已提交
917 918
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
919
		goto no_page_table;
L
Linus Torvalds 已提交
920 921 922

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
923
		goto no_page_table;
L
Linus Torvalds 已提交
924 925 926
	
	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
927 928 929 930 931
		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
932
		goto out;
933
	}
L
Linus Torvalds 已提交
934

935
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
936 937 938 939
	if (!ptep)
		goto out;

	pte = *ptep;
940 941 942 943
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
944 945
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
946
		goto unlock;
L
Linus Torvalds 已提交
947

948 949 950 951 952 953 954 955 956 957
	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
958
out:
959
	return page;
L
Linus Torvalds 已提交
960

961 962 963 964 965 966
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
N
Nick Piggin 已提交
967
		page = ZERO_PAGE(0);
968 969 970 971 972
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
973 974 975 976 977 978 979
}

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;
980
	unsigned int vm_flags;
L
Linus Torvalds 已提交
981 982 983 984 985

	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
986 987
	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
988 989 990
	i = 0;

	do {
991 992
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011

		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);
1012 1013
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1014
			pte = pte_offset_map(pmd, pg);
1015 1016 1017 1018
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1019
			if (pages) {
1020
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1021 1022 1023
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1024 1025 1026 1027 1028 1029 1030 1031 1032 1033
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1034
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1035
				|| !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1036 1037 1038 1039
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1040
						&start, &len, i, write);
L
Linus Torvalds 已提交
1041 1042
			continue;
		}
1043 1044 1045 1046 1047

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
		if (!write && !(vma->vm_flags & VM_LOCKED) &&
1048 1049
		    (!vma->vm_ops || (!vma->vm_ops->nopage &&
					!vma->vm_ops->fault)))
1050 1051
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1052
		do {
1053
			struct page *page;
L
Linus Torvalds 已提交
1054

1055 1056 1057 1058 1059 1060 1061 1062
			/*
			 * 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;

1063 1064
			if (write)
				foll_flags |= FOLL_WRITE;
1065

1066
			cond_resched();
1067
			while (!(page = follow_page(vma, start, foll_flags))) {
1068
				int ret;
N
Nick Piggin 已提交
1069
				ret = handle_mm_fault(mm, vma, start,
1070
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
					else if (ret & VM_FAULT_SIGBUS)
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1083
				/*
N
Nick Piggin 已提交
1084 1085 1086 1087 1088
				 * 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.
1089 1090
				 */
				if (ret & VM_FAULT_WRITE)
1091
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1092

1093
				cond_resched();
L
Linus Torvalds 已提交
1094 1095
			}
			if (pages) {
1096
				pages[i] = page;
1097

1098
				flush_anon_page(vma, page, start);
1099
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1100 1101 1102 1103 1104 1105
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1106 1107
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1108 1109 1110 1111
	return i;
}
EXPORT_SYMBOL(get_user_pages);

1112
pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1113 1114 1115 1116
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1117
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1118 1119 1120 1121 1122 1123
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1124 1125 1126 1127 1128 1129 1130 1131 1132 1133
/*
 * 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;
1134
	pte_t *pte;
1135 1136 1137
	spinlock_t *ptl;  

	retval = -EINVAL;
1138
	if (PageAnon(page))
1139 1140 1141
		goto out;
	retval = -ENOMEM;
	flush_dcache_page(page);
1142
	pte = get_locked_pte(mm, addr, &ptl);
1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161
	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;
}

1162 1163 1164 1165 1166 1167
/**
 * 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
 *
1168 1169 1170 1171 1172 1173
 * 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
1174
 * (see split_page()).
1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189
 *
 * 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;
1190
	vma->vm_flags |= VM_INSERTPAGE;
1191 1192
	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
1193
EXPORT_SYMBOL(vm_insert_page);
1194

N
Nick Piggin 已提交
1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239
/**
 * 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
1240 1241 1242 1243 1244 1245 1246 1247 1248 1249
/*
 * 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
1250
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1251

H
Hugh Dickins 已提交
1252
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1253 1254
	if (!pte)
		return -ENOMEM;
1255
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1256 1257
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1258
		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
L
Linus Torvalds 已提交
1259 1260
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1261
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1262
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305
	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;
}

1306 1307 1308 1309 1310 1311 1312 1313 1314 1315
/**
 * 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
1316 1317 1318 1319 1320
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;
1321
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1322 1323 1324 1325 1326 1327 1328 1329
	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
1330 1331 1332 1333 1334
	 *   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.
1335 1336 1337
	 *   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
1338 1339 1340 1341
	 *
	 * 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
1342
	 */
1343
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1344
		if (addr != vma->vm_start || end != vma->vm_end)
1345
			return -EINVAL;
L
Linus Torvalds 已提交
1346 1347 1348
		vma->vm_pgoff = pfn;
	}

1349
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365

	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);

1366 1367 1368 1369 1370 1371 1372
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;
1373
	spinlock_t *uninitialized_var(ptl);
1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459

	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);

1460 1461 1462 1463 1464 1465 1466 1467 1468
/*
 * 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
1469
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1470 1471 1472 1473 1474
				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
1475 1476
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1477
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1478
		spin_unlock(ptl);
1479 1480 1481 1482 1483 1484
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497
/*
 * 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;
}

1498
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1499 1500 1501 1502 1503 1504 1505 1506 1507
{
	/*
	 * 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
1508 1509 1510 1511 1512 1513 1514 1515 1516
		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))
1517 1518
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1519
		flush_dcache_page(dst);
1520
		return;
1521

1522
	}
1523
	copy_user_highpage(dst, src, va, vma);
1524 1525
}

L
Linus Torvalds 已提交
1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539
/*
 * 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.
 *
1540 1541 1542
 * 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
1543
 */
1544 1545
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1546
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1547
{
1548
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1549
	pte_t entry;
N
Nick Piggin 已提交
1550
	int reuse = 0, ret = 0;
1551
	int page_mkwrite = 0;
1552
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1553

1554 1555 1556
	old_page = vm_normal_page(vma, address, orig_pte);
	if (!old_page)
		goto gotten;
L
Linus Torvalds 已提交
1557

1558
	/*
P
Peter Zijlstra 已提交
1559 1560
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1561
	 */
P
Peter Zijlstra 已提交
1562 1563 1564 1565 1566 1567
	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)) ==
1568
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1569 1570 1571 1572 1573
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596
		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);
1597
			page_cache_release(old_page);
1598 1599
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1600 1601

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1602
		}
1603 1604
		dirty_page = old_page;
		get_page(dirty_page);
1605 1606 1607 1608 1609 1610 1611
		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);
1612
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1613
			update_mmu_cache(vma, address, entry);
1614 1615
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1616 1617 1618 1619 1620
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1621
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1622
gotten:
1623
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1624 1625

	if (unlikely(anon_vma_prepare(vma)))
1626
		goto oom;
N
Nick Piggin 已提交
1627 1628 1629 1630 1631
	VM_BUG_ON(old_page == ZERO_PAGE(0));
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
	if (!new_page)
		goto oom;
	cow_user_page(new_page, old_page, address, vma);
1632

L
Linus Torvalds 已提交
1633 1634 1635
	/*
	 * Re-check the pte - we dropped the lock
	 */
1636
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1637
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1638
		if (old_page) {
N
Nick Piggin 已提交
1639
			page_remove_rmap(old_page, vma);
H
Hugh Dickins 已提交
1640 1641 1642 1643 1644
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1645
			inc_mm_counter(mm, anon_rss);
1646
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1647 1648
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1649 1650 1651 1652 1653 1654 1655 1656
		/*
		 * 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);
1657
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1658
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1659
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1660 1661 1662

		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1663
		ret |= VM_FAULT_WRITE;
L
Linus Torvalds 已提交
1664
	}
H
Hugh Dickins 已提交
1665 1666 1667 1668
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1669
unlock:
1670
	pte_unmap_unlock(page_table, ptl);
1671
	if (dirty_page) {
1672 1673 1674
		if (vma->vm_file)
			file_update_time(vma->vm_file);

1675 1676 1677 1678 1679 1680 1681 1682 1683
		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
		 * do_no_page is protected similarly.
		 */
		wait_on_page_locked(dirty_page);
1684
		set_page_dirty_balance(dirty_page, page_mkwrite);
1685 1686
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1687
	return ret;
1688
oom:
H
Hugh Dickins 已提交
1689 1690
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1691
	return VM_FAULT_OOM;
1692 1693 1694 1695

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722
}

/*
 * 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
1723
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749
 * 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;

1750 1751
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
1752
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
1753 1754
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
1755 1756
	 */

L
Linus Torvalds 已提交
1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767
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;
		}
	}

1768 1769
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
1770
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
1771

1772
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1773 1774 1775 1776 1777 1778
		/* 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 */
1779
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
1780 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 1808 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 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845
		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;
	}
}

/**
1846
 * 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
1847
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883
 * @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);

1884
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900
	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);

1901 1902 1903 1904
/**
 * 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
1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923
 *
 * 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);
1924 1925 1926 1927 1928 1929 1930 1931 1932

	/*
	 * 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
1933 1934
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	truncate_inode_pages(mapping, offset);
1935
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
L
Linus Torvalds 已提交
1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958
	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);

1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970
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;

1971
	mutex_lock(&inode->i_mutex);
1972 1973 1974
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
1975
	unmap_mapping_range(mapping, offset, (end - offset), 1);
1976 1977
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
1978
	mutex_unlock(&inode->i_mutex);
1979 1980 1981 1982

	return 0;
}

L
Linus Torvalds 已提交
1983
/*
1984 1985 1986
 * 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
1987
 */
1988 1989 1990
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
1991
{
1992
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1993
	struct page *page;
1994
	swp_entry_t entry;
L
Linus Torvalds 已提交
1995
	pte_t pte;
N
Nick Piggin 已提交
1996
	int ret = 0;
L
Linus Torvalds 已提交
1997

H
Hugh Dickins 已提交
1998
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1999
		goto out;
2000 2001

	entry = pte_to_swp_entry(orig_pte);
2002 2003 2004 2005
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2006
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2007 2008
	page = lookup_swap_cache(entry);
	if (!page) {
2009
		grab_swap_token(); /* Contend for token _before_ read-in */
2010 2011
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2012 2013
		if (!page) {
			/*
2014 2015
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2016
			 */
2017
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2018 2019
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2020
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2021
			goto unlock;
L
Linus Torvalds 已提交
2022 2023 2024 2025
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2026
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2027 2028 2029 2030
	}

	mark_page_accessed(page);
	lock_page(page);
2031
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2032 2033

	/*
2034
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2035
	 */
2036
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2037
	if (unlikely(!pte_same(*page_table, orig_pte)))
2038 2039 2040 2041 2042
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2043 2044 2045 2046
	}

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

2047
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2048 2049 2050 2051 2052 2053 2054 2055 2056 2057
	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);

2058 2059 2060 2061 2062
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2063
	if (write_access) {
N
Nick Piggin 已提交
2064
		/* XXX: We could OR the do_wp_page code with this one? */
L
Linus Torvalds 已提交
2065
		if (do_wp_page(mm, vma, address,
N
Nick Piggin 已提交
2066
				page_table, pmd, ptl, pte) & VM_FAULT_OOM)
L
Linus Torvalds 已提交
2067 2068 2069 2070 2071 2072
			ret = VM_FAULT_OOM;
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2073
unlock:
2074
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2075 2076
out:
	return ret;
2077
out_nomap:
2078
	pte_unmap_unlock(page_table, ptl);
2079 2080
	unlock_page(page);
	page_cache_release(page);
2081
	return ret;
L
Linus Torvalds 已提交
2082 2083 2084
}

/*
2085 2086 2087
 * 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
2088
 */
2089 2090 2091
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
2092
{
2093 2094
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2095 2096
	pte_t entry;

N
Nick Piggin 已提交
2097 2098
	/* Allocate our own private page. */
	pte_unmap(page_table);
2099

N
Nick Piggin 已提交
2100 2101 2102 2103 2104
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
2105

N
Nick Piggin 已提交
2106 2107
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2108

N
Nick Piggin 已提交
2109 2110 2111 2112 2113 2114
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!pte_none(*page_table))
		goto release;
	inc_mm_counter(mm, anon_rss);
	lru_cache_add_active(page);
	page_add_new_anon_rmap(page, vma, address);
2115
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2116 2117

	/* No need to invalidate - it was non-present before */
2118 2119
	update_mmu_cache(vma, address, entry);
unlock:
2120
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2121
	return 0;
2122 2123 2124
release:
	page_cache_release(page);
	goto unlock;
2125
oom:
L
Linus Torvalds 已提交
2126 2127 2128 2129
	return VM_FAULT_OOM;
}

/*
2130
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2131
 * tries to share with existing pages, but makes a separate copy if
2132 2133
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2134 2135 2136 2137
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2138
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2139
 * but allow concurrent faults), and pte neither mapped nor locked.
2140
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2141
 */
2142
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2143
		unsigned long address, pmd_t *pmd,
2144
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2145
{
2146
	pte_t *page_table;
2147
	spinlock_t *ptl;
N
Nick Piggin 已提交
2148
	struct page *page;
L
Linus Torvalds 已提交
2149 2150
	pte_t entry;
	int anon = 0;
2151
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2152 2153
	struct vm_fault vmf;
	int ret;
2154
	int page_mkwrite = 0;
2155

N
Nick Piggin 已提交
2156 2157 2158 2159
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2160

2161 2162
	BUG_ON(vma->vm_flags & VM_PFNMAP);

2163
	if (likely(vma->vm_ops->fault)) {
N
Nick Piggin 已提交
2164
		ret = vma->vm_ops->fault(vma, &vmf);
N
Nick Piggin 已提交
2165 2166
		if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
			return ret;
2167 2168
	} else {
		/* Legacy ->nopage path */
N
Nick Piggin 已提交
2169
		ret = 0;
N
Nick Piggin 已提交
2170
		vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2171
		/* no page was available -- either SIGBUS or OOM */
N
Nick Piggin 已提交
2172
		if (unlikely(vmf.page == NOPAGE_SIGBUS))
2173
			return VM_FAULT_SIGBUS;
N
Nick Piggin 已提交
2174
		else if (unlikely(vmf.page == NOPAGE_OOM))
2175 2176
			return VM_FAULT_OOM;
	}
L
Linus Torvalds 已提交
2177

2178
	/*
N
Nick Piggin 已提交
2179
	 * For consistency in subsequent calls, make the faulted page always
2180 2181
	 * locked.
	 */
N
Nick Piggin 已提交
2182
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2183
		lock_page(vmf.page);
2184
	else
N
Nick Piggin 已提交
2185
		VM_BUG_ON(!PageLocked(vmf.page));
2186

L
Linus Torvalds 已提交
2187 2188 2189
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2190
	page = vmf.page;
2191
	if (flags & FAULT_FLAG_WRITE) {
2192
		if (!(vma->vm_flags & VM_SHARED)) {
2193
			anon = 1;
2194
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2195
				ret = VM_FAULT_OOM;
2196
				goto out;
2197
			}
N
Nick Piggin 已提交
2198 2199
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2200
			if (!page) {
N
Nick Piggin 已提交
2201
				ret = VM_FAULT_OOM;
2202
				goto out;
2203
			}
N
Nick Piggin 已提交
2204
			copy_user_highpage(page, vmf.page, address, vma);
2205
		} else {
2206 2207
			/*
			 * If the page will be shareable, see if the backing
2208
			 * address space wants to know that the page is about
2209 2210
			 * to become writable
			 */
2211 2212 2213
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2214 2215
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2216 2217 2218
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2219 2220 2221 2222 2223 2224 2225 2226
				/*
				 * XXX: this is not quite right (racy vs
				 * invalidate) to unlock and relock the page
				 * like this, however a better fix requires
				 * reworking page_mkwrite locking API, which
				 * is better done later.
				 */
				if (!page->mapping) {
N
Nick Piggin 已提交
2227
					ret = 0;
N
Nick Piggin 已提交
2228 2229 2230
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2231
				page_mkwrite = 1;
2232 2233
			}
		}
2234

L
Linus Torvalds 已提交
2235 2236
	}

2237
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249

	/*
	 * 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... */
2250
	if (likely(pte_same(*page_table, orig_pte))) {
2251 2252
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2253
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2254 2255 2256
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2257 2258 2259
                        inc_mm_counter(mm, anon_rss);
                        lru_cache_add_active(page);
                        page_add_new_anon_rmap(page, vma, address);
2260
		} else {
2261
			inc_mm_counter(mm, file_rss);
2262
			page_add_file_rmap(page);
2263
			if (flags & FAULT_FLAG_WRITE) {
2264
				dirty_page = page;
2265 2266
				get_page(dirty_page);
			}
2267
		}
2268 2269 2270

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2271
	} else {
2272 2273 2274
		if (anon)
			page_cache_release(page);
		else
2275
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2276 2277
	}

2278
	pte_unmap_unlock(page_table, ptl);
2279 2280

out:
N
Nick Piggin 已提交
2281
	unlock_page(vmf.page);
2282
out_unlocked:
2283
	if (anon)
N
Nick Piggin 已提交
2284
		page_cache_release(vmf.page);
2285
	else if (dirty_page) {
2286 2287 2288
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2289
		set_page_dirty_balance(dirty_page, page_mkwrite);
2290 2291
		put_page(dirty_page);
	}
2292

N
Nick Piggin 已提交
2293
	return ret;
2294
}
2295

2296 2297 2298 2299 2300
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)
2301
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2302 2303
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2304 2305
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2306 2307
}

L
Linus Torvalds 已提交
2308

J
Jes Sorensen 已提交
2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337
/*
 * do_no_pfn() tries to create a new page mapping for a page without
 * a struct_page backing it
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
 *
 * It is expected that the ->nopfn handler always returns the same pfn
 * for a given virtual mapping.
 *
 * Mark this `noinline' to prevent it from bloating the main pagefault code.
 */
static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
		     unsigned long address, pte_t *page_table, pmd_t *pmd,
		     int write_access)
{
	spinlock_t *ptl;
	pte_t entry;
	unsigned long pfn;

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

	pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
2338
	if (unlikely(pfn == NOPFN_OOM))
J
Jes Sorensen 已提交
2339
		return VM_FAULT_OOM;
2340
	else if (unlikely(pfn == NOPFN_SIGBUS))
J
Jes Sorensen 已提交
2341
		return VM_FAULT_SIGBUS;
2342
	else if (unlikely(pfn == NOPFN_REFAULT))
N
Nick Piggin 已提交
2343
		return 0;
J
Jes Sorensen 已提交
2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354

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

	/* Only go through if we didn't race with anybody else... */
	if (pte_none(*page_table)) {
		entry = pfn_pte(pfn, vma->vm_page_prot);
		if (write_access)
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
	}
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2355
	return 0;
J
Jes Sorensen 已提交
2356 2357
}

L
Linus Torvalds 已提交
2358 2359 2360 2361
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2362 2363 2364 2365
 *
 * 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
2366
 */
N
Nick Piggin 已提交
2367
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2368 2369
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2370
{
N
Nick Piggin 已提交
2371 2372
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2373
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2374

H
Hugh Dickins 已提交
2375
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2376
		return 0;
L
Linus Torvalds 已提交
2377

N
Nick Piggin 已提交
2378 2379
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2380 2381 2382
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2383
		print_bad_pte(vma, orig_pte, address);
2384 2385 2386 2387
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2388
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399
}

/*
 * 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
2400 2401 2402
 * 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
2403 2404
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2405 2406
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2407 2408
{
	pte_t entry;
2409
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2410

2411
	entry = *pte;
L
Linus Torvalds 已提交
2412
	if (!pte_present(entry)) {
2413
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2414
			if (vma->vm_ops) {
2415 2416 2417
				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
2418 2419 2420 2421 2422 2423
				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);
2424
		}
L
Linus Torvalds 已提交
2425
		if (pte_file(entry))
N
Nick Piggin 已提交
2426
			return do_nonlinear_fault(mm, vma, address,
2427 2428 2429
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2430 2431
	}

H
Hugh Dickins 已提交
2432
	ptl = pte_lockptr(mm, pmd);
2433 2434 2435
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2436 2437
	if (write_access) {
		if (!pte_write(entry))
2438 2439
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2440 2441 2442
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2443
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454
		update_mmu_cache(vma, address, entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2455 2456
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2457
	return 0;
L
Linus Torvalds 已提交
2458 2459 2460 2461 2462
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2463
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2464 2465 2466 2467 2468 2469 2470 2471 2472
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2473
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2474

2475 2476
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2477 2478 2479 2480

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2481
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2482 2483
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2484
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2485 2486
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2487
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2488

H
Hugh Dickins 已提交
2489
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2490 2491 2492 2493 2494
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2495
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2496
 */
2497
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2498
{
H
Hugh Dickins 已提交
2499 2500
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2501
		return -ENOMEM;
L
Linus Torvalds 已提交
2502

H
Hugh Dickins 已提交
2503
	spin_lock(&mm->page_table_lock);
2504
	if (pgd_present(*pgd))		/* Another has populated it */
L
Linus Torvalds 已提交
2505
		pud_free(new);
2506 2507
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2508
	spin_unlock(&mm->page_table_lock);
2509
	return 0;
L
Linus Torvalds 已提交
2510 2511 2512 2513 2514 2515
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2516
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2517
 */
2518
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2519
{
H
Hugh Dickins 已提交
2520 2521
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2522
		return -ENOMEM;
L
Linus Torvalds 已提交
2523

H
Hugh Dickins 已提交
2524
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2525
#ifndef __ARCH_HAS_4LEVEL_HACK
2526
	if (pud_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2527
		pmd_free(new);
2528 2529
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2530
#else
2531
	if (pgd_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2532
		pmd_free(new);
2533 2534
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2535
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2536
	spin_unlock(&mm->page_table_lock);
2537
	return 0;
2538
}
L
Linus Torvalds 已提交
2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549
#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;
2550 2551
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2552
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2553 2554 2555 2556 2557 2558 2559 2560 2561 2562
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
	if (ret < 0)
		return ret;
	return ret == len ? 0 : -1;
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2563
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2564 2565 2566 2567 2568 2569

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
2570 2571
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2572 2573 2574 2575 2576 2577 2578
	/*
	 * 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
2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602
	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 */
2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620

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

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

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
2621
	/* ignore errors, just check how much was successfully transferred */
2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655
	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;
}
2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686

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

	down_read(&mm->mmap_sem);
	vma = find_vma(mm, ip);
	if (vma && vma->vm_file) {
		struct file *f = vma->vm_file;
		char *buf = (char *)__get_free_page(GFP_KERNEL);
		if (buf) {
			char *p, *s;

			p = d_path(f->f_dentry, f->f_vfsmnt, buf, PAGE_SIZE);
			if (IS_ERR(p))
				p = "?";
			s = strrchr(p, '/');
			if (s)
				p = s+1;
			printk("%s%s[%lx+%lx]", prefix, p,
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
	up_read(&current->mm->mmap_sem);
}