memory.c 71.3 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 85 86
/* 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;
unsigned long vmalloc_earlyreserve;

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);
EXPORT_SYMBOL(vmalloc_earlyreserve);

87 88 89 90 91
int randomize_va_space __read_mostly = 1;

static int __init disable_randmaps(char *s)
{
	randomize_va_space = 0;
92
	return 1;
93 94 95 96
}
__setup("norandmaps", disable_randmaps);


L
Linus Torvalds 已提交
97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124
/*
 * 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.
 */
125
static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
L
Linus Torvalds 已提交
126
{
127 128
	struct page *page = pmd_page(*pmd);
	pmd_clear(pmd);
H
Hugh Dickins 已提交
129
	pte_lock_deinit(page);
130
	pte_free_tlb(tlb, page);
131
	dec_zone_page_state(page, NR_PAGETABLE);
132
	tlb->mm->nr_ptes--;
L
Linus Torvalds 已提交
133 134
}

135 136 137
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
138 139 140
{
	pmd_t *pmd;
	unsigned long next;
141
	unsigned long start;
L
Linus Torvalds 已提交
142

143
	start = addr;
L
Linus Torvalds 已提交
144 145 146 147 148
	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			continue;
149
		free_pte_range(tlb, pmd);
L
Linus Torvalds 已提交
150 151
	} while (pmd++, addr = next, addr != end);

152 153 154 155 156 157 158
	start &= PUD_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
L
Linus Torvalds 已提交
159
	}
160 161 162 163 164 165
	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
166 167
}

168 169 170
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
171 172 173
{
	pud_t *pud;
	unsigned long next;
174
	unsigned long start;
L
Linus Torvalds 已提交
175

176
	start = addr;
L
Linus Torvalds 已提交
177 178 179 180 181
	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
182
		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
L
Linus Torvalds 已提交
183 184
	} while (pud++, addr = next, addr != end);

185 186 187 188 189 190 191
	start &= PGDIR_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
L
Linus Torvalds 已提交
192
	}
193 194 195 196 197 198
	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
199 200 201
}

/*
202 203
 * This function frees user-level page tables of a process.
 *
L
Linus Torvalds 已提交
204 205
 * Must be called with pagetable lock held.
 */
206
void free_pgd_range(struct mmu_gather **tlb,
207 208
			unsigned long addr, unsigned long end,
			unsigned long floor, unsigned long ceiling)
L
Linus Torvalds 已提交
209 210 211
{
	pgd_t *pgd;
	unsigned long next;
212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238
	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
239

240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256
	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;
257
	pgd = pgd_offset((*tlb)->mm, addr);
L
Linus Torvalds 已提交
258 259 260 261
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
262
		free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
L
Linus Torvalds 已提交
263
	} while (pgd++, addr = next, addr != end);
264

265
	if (!(*tlb)->fullmm)
266
		flush_tlb_pgtables((*tlb)->mm, start, end);
267 268 269
}

void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
270
		unsigned long floor, unsigned long ceiling)
271 272 273 274 275
{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

276 277 278 279 280 281
		/*
		 * Hide vma from rmap and vmtruncate before freeing pgtables
		 */
		anon_vma_unlink(vma);
		unlink_file_vma(vma);

282
		if (is_vm_hugetlb_page(vma)) {
283
			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
284
				floor, next? next->vm_start: ceiling);
285 286 287 288 289
		} else {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
290
			       && !is_vm_hugetlb_page(next)) {
291 292
				vma = next;
				next = vma->vm_next;
293 294
				anon_vma_unlink(vma);
				unlink_file_vma(vma);
295 296 297 298
			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
299 300
		vma = next;
	}
L
Linus Torvalds 已提交
301 302
}

303
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
304
{
H
Hugh Dickins 已提交
305
	struct page *new = pte_alloc_one(mm, address);
306 307 308
	if (!new)
		return -ENOMEM;

H
Hugh Dickins 已提交
309
	pte_lock_init(new);
H
Hugh Dickins 已提交
310
	spin_lock(&mm->page_table_lock);
H
Hugh Dickins 已提交
311 312
	if (pmd_present(*pmd)) {	/* Another has populated it */
		pte_lock_deinit(new);
313
		pte_free(new);
H
Hugh Dickins 已提交
314
	} else {
L
Linus Torvalds 已提交
315
		mm->nr_ptes++;
316
		inc_zone_page_state(new, NR_PAGETABLE);
L
Linus Torvalds 已提交
317 318
		pmd_populate(mm, pmd, new);
	}
H
Hugh Dickins 已提交
319
	spin_unlock(&mm->page_table_lock);
320
	return 0;
L
Linus Torvalds 已提交
321 322
}

323
int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
324
{
325 326 327 328 329 330 331 332 333 334 335
	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
336 337
}

338 339 340 341 342 343 344 345
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
346
/*
347 348 349
 * 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
350 351 352 353 354 355 356 357 358 359 360 361 362
 *
 * 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();
}

363 364 365 366 367
static inline int is_cow_mapping(unsigned int flags)
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

H
Hugh Dickins 已提交
368
/*
369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386
 * 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
387
 */
388
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
H
Hugh Dickins 已提交
389
{
390 391
	unsigned long pfn = pte_pfn(pte);

N
Nick Piggin 已提交
392
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
393 394 395
		unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
		if (pfn == vma->vm_pgoff + off)
			return NULL;
396
		if (!is_cow_mapping(vma->vm_flags))
L
Linus Torvalds 已提交
397
			return NULL;
398 399
	}

400 401 402 403 404 405
	/*
	 * 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.
	 */
406 407 408 409 410 411 412 413 414 415 416 417 418
	if (unlikely(!pfn_valid(pfn))) {
		print_bad_pte(vma, pte, addr);
		return NULL;
	}

	/*
	 * NOTE! We still have PageReserved() pages in the page 
	 * tables. 
	 *
	 * The PAGE_ZERO() pages and various VDSO mappings can
	 * cause them to exist.
	 */
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
419 420
}

L
Linus Torvalds 已提交
421 422 423 424 425 426
/*
 * 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
427
static inline void
L
Linus Torvalds 已提交
428
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
429
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
430
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
431
{
N
Nick Piggin 已提交
432
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
433 434 435 436 437 438
	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)) {
439 440 441
			swp_entry_t entry = pte_to_swp_entry(pte);

			swap_duplicate(entry);
L
Linus Torvalds 已提交
442 443 444
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
445 446 447
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
448 449
				spin_unlock(&mmlist_lock);
			}
450 451 452 453 454 455 456 457 458 459
			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
460
		}
461
		goto out_set_pte;
L
Linus Torvalds 已提交
462 463 464 465 466 467
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
468
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
469
		ptep_set_wrprotect(src_mm, addr, src_pte);
470
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
471 472 473 474 475 476 477 478 479
	}

	/*
	 * 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);
480 481 482 483 484 485 486

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
		page_dup_rmap(page);
		rss[!!PageAnon(page)]++;
	}
487 488 489

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
L
Linus Torvalds 已提交
490 491 492 493 494 495 496
}

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
497
	spinlock_t *src_ptl, *dst_ptl;
498
	int progress = 0;
H
Hugh Dickins 已提交
499
	int rss[2];
L
Linus Torvalds 已提交
500 501

again:
502
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
503
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
504 505 506
	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
507
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
508
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
509
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
510 511 512 513 514 515

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
516 517 518
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
H
Hugh Dickins 已提交
519 520
			    need_lockbreak(src_ptl) ||
			    need_lockbreak(dst_ptl))
521 522
				break;
		}
L
Linus Torvalds 已提交
523 524 525 526
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
527
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
528 529 530
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

531
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
532
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
533
	pte_unmap_nested(src_pte - 1);
534
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
535 536
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
L
Linus Torvalds 已提交
537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593
	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;

594 595 596 597 598 599
	/*
	 * 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.
	 */
600
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
601 602 603 604
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620
	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;
}

621
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
622
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
623
				unsigned long addr, unsigned long end,
624
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
625
{
N
Nick Piggin 已提交
626
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
627
	pte_t *pte;
628
	spinlock_t *ptl;
629 630
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
631

632
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
633
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
634 635
	do {
		pte_t ptent = *pte;
636 637
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
638
			continue;
639
		}
640 641 642

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
643
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
644
			struct page *page;
645

646
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664
			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
665
			ptent = ptep_get_and_clear_full(mm, addr, pte,
666
							tlb->fullmm);
L
Linus Torvalds 已提交
667 668 669 670 671 672
			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
673
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
674 675
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
676
				anon_rss--;
677 678 679 680 681
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
				if (pte_young(ptent))
					mark_page_accessed(page);
H
Hugh Dickins 已提交
682
				file_rss--;
683
			}
L
Linus Torvalds 已提交
684 685 686 687 688 689 690 691 692 693 694 695
			page_remove_rmap(page);
			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));
696
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
697
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
698

H
Hugh Dickins 已提交
699
	add_mm_rss(mm, file_rss, anon_rss);
700
	arch_leave_lazy_mmu_mode();
701
	pte_unmap_unlock(pte - 1, ptl);
702 703

	return addr;
L
Linus Torvalds 已提交
704 705
}

706
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
707
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
708
				unsigned long addr, unsigned long end,
709
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
710 711 712 713 714 715 716
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
717 718
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
719
			continue;
720 721 722 723 724 725
		}
		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
726 727
}

728
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
729
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
730
				unsigned long addr, unsigned long end,
731
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
732 733 734 735 736 737 738
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
739 740
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
741
			continue;
742 743 744 745 746 747
		}
		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
748 749
}

750 751
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
752
				unsigned long addr, unsigned long end,
753
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
754 755 756 757 758 759 760 761 762 763 764 765
{
	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);
766 767
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
768
			continue;
769 770 771 772
		}
		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
773
	tlb_end_vma(tlb, vma);
774 775

	return addr;
L
Linus Torvalds 已提交
776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793
}

#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
 *
794
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
795
 *
796
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
797
 *
798 799
 * 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
800 801 802 803 804 805 806 807 808 809 810
 * 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.
 */
811
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
812 813 814 815
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
816
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
817 818
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
819
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
820
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
821
	int fullmm = (*tlbp)->fullmm;
L
Linus Torvalds 已提交
822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841

	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;
			}

842
			if (unlikely(is_vm_hugetlb_page(vma))) {
L
Linus Torvalds 已提交
843
				unmap_hugepage_range(vma, start, end);
844 845 846 847 848 849 850 851 852 853
				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
854 855 856 857 858 859 860
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
				(i_mmap_lock && need_lockbreak(i_mmap_lock))) {
				if (i_mmap_lock) {
861
					*tlbp = NULL;
L
Linus Torvalds 已提交
862 863 864 865 866
					goto out;
				}
				cond_resched();
			}

867
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
868
			tlb_start_valid = 0;
869
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
870 871 872
		}
	}
out:
873
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
874 875 876 877 878 879 880 881 882
}

/**
 * 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
 */
883
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
884 885 886 887 888 889 890 891 892
		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);
893
	update_hiwater_rss(mm);
894 895 896
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
897
	return end;
L
Linus Torvalds 已提交
898 899 900 901 902
}

/*
 * Do a quick page-table lookup for a single page.
 */
903
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
904
			unsigned int flags)
L
Linus Torvalds 已提交
905 906 907 908 909
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
910
	spinlock_t *ptl;
L
Linus Torvalds 已提交
911
	struct page *page;
912
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
913

914 915 916 917 918
	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
919

920
	page = NULL;
L
Linus Torvalds 已提交
921 922
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
923
		goto no_page_table;
L
Linus Torvalds 已提交
924 925 926

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
927
		goto no_page_table;
L
Linus Torvalds 已提交
928 929 930
	
	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
931 932 933 934 935
		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
936
		goto out;
937
	}
L
Linus Torvalds 已提交
938

939
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
940 941 942 943
	if (!ptep)
		goto out;

	pte = *ptep;
944 945 946 947
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
948 949
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
950
		goto unlock;
L
Linus Torvalds 已提交
951

952 953 954 955 956 957 958 959 960 961
	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
962
out:
963
	return page;
L
Linus Torvalds 已提交
964

965 966 967 968 969 970 971 972 973 974 975 976
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
		page = ZERO_PAGE(address);
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
977 978 979 980 981 982 983
}

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;
984
	unsigned int vm_flags;
L
Linus Torvalds 已提交
985 986 987 988 989

	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
990 991
	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
992 993 994
	i = 0;

	do {
995 996
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015

		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);
1016 1017
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1018
			pte = pte_offset_map(pmd, pg);
1019 1020 1021 1022
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1023
			if (pages) {
1024
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1025 1026 1027
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

1038
		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1039
				|| !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1040 1041 1042 1043 1044 1045 1046
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
						&start, &len, i);
			continue;
		}
1047 1048 1049 1050 1051 1052 1053 1054

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

L
Linus Torvalds 已提交
1055
		do {
1056
			struct page *page;
L
Linus Torvalds 已提交
1057

1058 1059
			if (write)
				foll_flags |= FOLL_WRITE;
1060

1061
			cond_resched();
1062
			while (!(page = follow_page(vma, start, foll_flags))) {
1063 1064 1065
				int ret;
				ret = __handle_mm_fault(mm, vma, start,
						foll_flags & FOLL_WRITE);
1066 1067 1068 1069 1070 1071 1072
				/*
				 * The VM_FAULT_WRITE bit tells us that do_wp_page has
				 * broken COW when necessary, even if maybe_mkwrite
				 * decided not to set pte_write. We can thus safely do
				 * subsequent page lookups as if they were reads.
				 */
				if (ret & VM_FAULT_WRITE)
1073
					foll_flags &= ~FOLL_WRITE;
1074 1075
				
				switch (ret & ~VM_FAULT_WRITE) {
L
Linus Torvalds 已提交
1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088
				case VM_FAULT_MINOR:
					tsk->min_flt++;
					break;
				case VM_FAULT_MAJOR:
					tsk->maj_flt++;
					break;
				case VM_FAULT_SIGBUS:
					return i ? i : -EFAULT;
				case VM_FAULT_OOM:
					return i ? i : -ENOMEM;
				default:
					BUG();
				}
1089
				cond_resched();
L
Linus Torvalds 已提交
1090 1091
			}
			if (pages) {
1092
				pages[i] = page;
1093 1094

				flush_anon_page(page, start);
1095
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1096 1097 1098 1099 1100 1101
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1102 1103
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1104 1105 1106 1107 1108 1109 1110 1111
	return i;
}
EXPORT_SYMBOL(get_user_pages);

static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
			unsigned long addr, unsigned long end, pgprot_t prot)
{
	pte_t *pte;
H
Hugh Dickins 已提交
1112
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1113

H
Hugh Dickins 已提交
1114
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1115 1116
	if (!pte)
		return -ENOMEM;
1117
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1118
	do {
N
Nick Piggin 已提交
1119 1120 1121 1122 1123
		struct page *page = ZERO_PAGE(addr);
		pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
		page_cache_get(page);
		page_add_file_rmap(page);
		inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
1124 1125 1126
		BUG_ON(!pte_none(*pte));
		set_pte_at(mm, addr, pte, zero_pte);
	} while (pte++, addr += PAGE_SIZE, addr != end);
1127
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1128
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186
	return 0;
}

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

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

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

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

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

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

1187
pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1188 1189 1190 1191
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1192
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1193 1194 1195 1196 1197 1198
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1199 1200 1201 1202 1203 1204 1205 1206 1207 1208
/*
 * 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;
1209
	pte_t *pte;
1210 1211 1212
	spinlock_t *ptl;  

	retval = -EINVAL;
1213
	if (PageAnon(page))
1214 1215 1216
		goto out;
	retval = -ENOMEM;
	flush_dcache_page(page);
1217
	pte = get_locked_pte(mm, addr, &ptl);
1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236
	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;
}

1237 1238 1239 1240 1241 1242
/**
 * 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
 *
1243 1244 1245 1246 1247 1248
 * 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
1249
 * (see split_page()).
1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264
 *
 * 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;
1265
	vma->vm_flags |= VM_INSERTPAGE;
1266 1267
	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
1268
EXPORT_SYMBOL(vm_insert_page);
1269

L
Linus Torvalds 已提交
1270 1271 1272 1273 1274 1275 1276 1277 1278 1279
/*
 * 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
1280
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1281

H
Hugh Dickins 已提交
1282
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1283 1284
	if (!pte)
		return -ENOMEM;
1285
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1286 1287
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1288
		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
L
Linus Torvalds 已提交
1289 1290
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1291
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1292
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335
	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;
}

1336 1337 1338 1339 1340 1341 1342 1343 1344 1345
/**
 * 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
1346 1347 1348 1349 1350
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;
1351
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1352 1353 1354 1355 1356 1357 1358 1359
	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
1360 1361 1362 1363 1364
	 *   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.
1365 1366 1367
	 *   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
1368 1369 1370 1371
	 *
	 * 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
1372
	 */
1373
	if (is_cow_mapping(vma->vm_flags)) {
L
Linus Torvalds 已提交
1374
		if (addr != vma->vm_start || end != vma->vm_end)
1375
			return -EINVAL;
L
Linus Torvalds 已提交
1376 1377 1378
		vma->vm_pgoff = pfn;
	}

1379
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395

	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);

1396 1397 1398 1399 1400 1401 1402 1403 1404
/*
 * 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
1405
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1406 1407 1408 1409 1410
				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
1411 1412
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1413
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1414
		spin_unlock(ptl);
1415 1416 1417 1418 1419 1420
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433
/*
 * 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;
}

1434 1435 1436 1437 1438 1439 1440 1441 1442 1443
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
{
	/*
	 * 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
1444 1445 1446 1447 1448 1449 1450 1451 1452
		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))
1453 1454
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1455
		flush_dcache_page(dst);
1456 1457 1458 1459 1460 1461
		return;
		
	}
	copy_user_highpage(dst, src, va);
}

L
Linus Torvalds 已提交
1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475
/*
 * 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.
 *
1476 1477 1478
 * 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
1479
 */
1480 1481
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1482
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1483
{
1484
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1485
	pte_t entry;
1486 1487
	int reuse = 0, ret = VM_FAULT_MINOR;
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1488

1489 1490 1491
	old_page = vm_normal_page(vma, address, orig_pte);
	if (!old_page)
		goto gotten;
L
Linus Torvalds 已提交
1492

1493
	/*
P
Peter Zijlstra 已提交
1494 1495
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1496
	 */
P
Peter Zijlstra 已提交
1497 1498 1499 1500 1501 1502
	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)) ==
1503
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1504 1505 1506 1507 1508
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535
		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;

			page_cache_release(old_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);
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
L
Linus Torvalds 已提交
1536
		}
1537 1538
		dirty_page = old_page;
		get_page(dirty_page);
1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550
		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);
		ptep_set_access_flags(vma, address, page_table, entry, 1);
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(entry);
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1551 1552 1553 1554 1555
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1556
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1557
gotten:
1558
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1559 1560

	if (unlikely(anon_vma_prepare(vma)))
1561
		goto oom;
1562
	if (old_page == ZERO_PAGE(address)) {
L
Linus Torvalds 已提交
1563 1564
		new_page = alloc_zeroed_user_highpage(vma, address);
		if (!new_page)
1565
			goto oom;
L
Linus Torvalds 已提交
1566 1567 1568
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
		if (!new_page)
1569
			goto oom;
1570
		cow_user_page(new_page, old_page, address);
L
Linus Torvalds 已提交
1571
	}
1572

L
Linus Torvalds 已提交
1573 1574 1575
	/*
	 * Re-check the pte - we dropped the lock
	 */
1576
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1577
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1578 1579 1580 1581 1582 1583 1584
		if (old_page) {
			page_remove_rmap(old_page);
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1585
			inc_mm_counter(mm, anon_rss);
1586
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1587 1588
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1589
		lazy_mmu_prot_update(entry);
1590 1591 1592 1593 1594 1595 1596 1597
		/*
		 * 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);
1598
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
1599
		lru_cache_add_active(new_page);
N
Nick Piggin 已提交
1600
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1601 1602 1603

		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1604
		ret |= VM_FAULT_WRITE;
L
Linus Torvalds 已提交
1605
	}
H
Hugh Dickins 已提交
1606 1607 1608 1609
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1610
unlock:
1611
	pte_unmap_unlock(page_table, ptl);
1612
	if (dirty_page) {
P
Peter Zijlstra 已提交
1613
		set_page_dirty_balance(dirty_page);
1614 1615
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
1616
	return ret;
1617
oom:
H
Hugh Dickins 已提交
1618 1619
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
1620
	return VM_FAULT_OOM;
1621 1622 1623 1624

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651
}

/*
 * 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
1652
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689
 * 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;

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;
		}
	}

1690 1691
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
L
Linus Torvalds 已提交
1692 1693 1694
	need_break = need_resched() ||
			need_lockbreak(details->i_mmap_lock);

1695
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
1696 1697 1698 1699 1700 1701
		/* 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 */
1702
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 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 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771
		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;
	}
}

/**
 * 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
1772
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
1773 1774 1775 1776 1777 1778 1779 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
 * @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);

	/* serialize i_size write against truncate_count write */
	smp_wmb();
	/* Protect against page faults, and endless unmapping loops */
	mapping->truncate_count++;
	/*
	 * For archs where spin_lock has inclusive semantics like ia64
	 * this smp_mb() will prevent to read pagetable contents
	 * before the truncate_count increment is visible to
	 * other cpus.
	 */
	smp_mb();
	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);

1835 1836 1837 1838
/**
 * 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
1839 1840 1841 1842 1843 1844 1845 1846 1847 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
 *
 * 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);
	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	truncate_inode_pages(mapping, offset);
	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);

1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894
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;

1895
	mutex_lock(&inode->i_mutex);
1896 1897 1898 1899 1900
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
1901
	mutex_unlock(&inode->i_mutex);
1902 1903 1904 1905

	return 0;
}

1906 1907 1908 1909 1910 1911
/**
 * swapin_readahead - swap in pages in hope we need them soon
 * @entry: swap entry of this memory
 * @addr: address to start
 * @vma: user vma this addresses belong to
 *
L
Linus Torvalds 已提交
1912 1913 1914
 * Primitive swap readahead code. We simply read an aligned block of
 * (1 << page_cluster) entries in the swap area. This method is chosen
 * because it doesn't cost us any seek time.  We also make sure to queue
1915
 * the 'original' request together with the readahead ones...
L
Linus Torvalds 已提交
1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967
 *
 * This has been extended to use the NUMA policies from the mm triggering
 * the readahead.
 *
 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
 */
void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
{
#ifdef CONFIG_NUMA
	struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
#endif
	int i, num;
	struct page *new_page;
	unsigned long offset;

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

/*
1968 1969 1970
 * 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
1971
 */
1972 1973 1974
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
1975
{
1976
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1977
	struct page *page;
1978
	swp_entry_t entry;
L
Linus Torvalds 已提交
1979 1980 1981
	pte_t pte;
	int ret = VM_FAULT_MINOR;

H
Hugh Dickins 已提交
1982
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1983
		goto out;
1984 1985

	entry = pte_to_swp_entry(orig_pte);
1986 1987 1988 1989
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
1990
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
1991 1992
	page = lookup_swap_cache(entry);
	if (!page) {
1993
		grab_swap_token(); /* Contend for token _before_ read-in */
L
Linus Torvalds 已提交
1994 1995 1996 1997
 		swapin_readahead(entry, address, vma);
 		page = read_swap_cache_async(entry, vma, address);
		if (!page) {
			/*
1998 1999
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2000
			 */
2001
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2002 2003
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2004
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2005
			goto unlock;
L
Linus Torvalds 已提交
2006 2007 2008 2009
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2010
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2011 2012
	}

2013
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2014 2015 2016 2017
	mark_page_accessed(page);
	lock_page(page);

	/*
2018
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2019
	 */
2020
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2021
	if (unlikely(!pte_same(*page_table, orig_pte)))
2022 2023 2024 2025 2026
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2027 2028 2029 2030
	}

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

2031
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2032 2033 2034 2035 2036 2037 2038 2039 2040 2041
	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);

2042 2043 2044 2045 2046
	swap_free(entry);
	if (vm_swap_full())
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2047 2048
	if (write_access) {
		if (do_wp_page(mm, vma, address,
2049
				page_table, pmd, ptl, pte) == VM_FAULT_OOM)
L
Linus Torvalds 已提交
2050 2051 2052 2053 2054 2055 2056
			ret = VM_FAULT_OOM;
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
	lazy_mmu_prot_update(pte);
2057
unlock:
2058
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2059 2060
out:
	return ret;
2061
out_nomap:
2062
	pte_unmap_unlock(page_table, ptl);
2063 2064
	unlock_page(page);
	page_cache_release(page);
2065
	return ret;
L
Linus Torvalds 已提交
2066 2067 2068
}

/*
2069 2070 2071
 * 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
2072
 */
2073 2074 2075
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
2076
{
2077 2078
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2079 2080
	pte_t entry;

2081
	if (write_access) {
L
Linus Torvalds 已提交
2082 2083 2084 2085
		/* Allocate our own private page. */
		pte_unmap(page_table);

		if (unlikely(anon_vma_prepare(vma)))
2086 2087
			goto oom;
		page = alloc_zeroed_user_highpage(vma, address);
L
Linus Torvalds 已提交
2088
		if (!page)
2089
			goto oom;
L
Linus Torvalds 已提交
2090

2091 2092
		entry = mk_pte(page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2093 2094 2095 2096 2097

		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
		if (!pte_none(*page_table))
			goto release;
		inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2098
		lru_cache_add_active(page);
N
Nick Piggin 已提交
2099
		page_add_new_anon_rmap(page, vma, address);
N
Nick Piggin 已提交
2100
	} else {
2101 2102 2103 2104 2105
		/* Map the ZERO_PAGE - vm_page_prot is readonly */
		page = ZERO_PAGE(address);
		page_cache_get(page);
		entry = mk_pte(page, vma->vm_page_prot);

H
Hugh Dickins 已提交
2106
		ptl = pte_lockptr(mm, pmd);
2107 2108 2109
		spin_lock(ptl);
		if (!pte_none(*page_table))
			goto release;
N
Nick Piggin 已提交
2110 2111
		inc_mm_counter(mm, file_rss);
		page_add_file_rmap(page);
L
Linus Torvalds 已提交
2112 2113
	}

2114
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2115 2116

	/* No need to invalidate - it was non-present before */
2117
	update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2118
	lazy_mmu_prot_update(entry);
2119
unlock:
2120
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2121
	return VM_FAULT_MINOR;
2122 2123 2124
release:
	page_cache_release(page);
	goto unlock;
2125
oom:
L
Linus Torvalds 已提交
2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137
	return VM_FAULT_OOM;
}

/*
 * do_no_page() tries to create a new page mapping. It aggressively
 * tries to share with existing pages, but makes a separate copy if
 * the "write_access" parameter is true in order to avoid the next
 * page fault.
 *
 * 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 2139 2140
 * 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
2141
 */
2142 2143 2144
static int do_no_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
2145
{
2146
	spinlock_t *ptl;
2147
	struct page *new_page;
L
Linus Torvalds 已提交
2148 2149 2150 2151 2152
	struct address_space *mapping = NULL;
	pte_t entry;
	unsigned int sequence = 0;
	int ret = VM_FAULT_MINOR;
	int anon = 0;
2153
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2154 2155

	pte_unmap(page_table);
2156 2157
	BUG_ON(vma->vm_flags & VM_PFNMAP);

L
Linus Torvalds 已提交
2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;
		sequence = mapping->truncate_count;
		smp_rmb(); /* serializes i_size against truncate_count */
	}
retry:
	new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
	/*
	 * No smp_rmb is needed here as long as there's a full
	 * spin_lock/unlock sequence inside the ->nopage callback
	 * (for the pagecache lookup) that acts as an implicit
	 * smp_mb() and prevents the i_size read to happen
	 * after the next truncate_count read.
	 */

2173 2174
	/* no page was available -- either SIGBUS, OOM or REFAULT */
	if (unlikely(new_page == NOPAGE_SIGBUS))
L
Linus Torvalds 已提交
2175
		return VM_FAULT_SIGBUS;
2176
	else if (unlikely(new_page == NOPAGE_OOM))
L
Linus Torvalds 已提交
2177
		return VM_FAULT_OOM;
2178 2179
	else if (unlikely(new_page == NOPAGE_REFAULT))
		return VM_FAULT_MINOR;
L
Linus Torvalds 已提交
2180 2181 2182 2183

	/*
	 * Should we do an early C-O-W break?
	 */
2184 2185 2186
	if (write_access) {
		if (!(vma->vm_flags & VM_SHARED)) {
			struct page *page;
L
Linus Torvalds 已提交
2187

2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208
			if (unlikely(anon_vma_prepare(vma)))
				goto oom;
			page = alloc_page_vma(GFP_HIGHUSER, vma, address);
			if (!page)
				goto oom;
			copy_user_highpage(page, new_page, address);
			page_cache_release(new_page);
			new_page = page;
			anon = 1;

		} else {
			/* if the page will be shareable, see if the backing
			 * address space wants to know that the page is about
			 * to become writable */
			if (vma->vm_ops->page_mkwrite &&
			    vma->vm_ops->page_mkwrite(vma, new_page) < 0
			    ) {
				page_cache_release(new_page);
				return VM_FAULT_SIGBUS;
			}
		}
L
Linus Torvalds 已提交
2209 2210
	}

2211
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2212 2213 2214 2215 2216 2217
	/*
	 * For a file-backed vma, someone could have truncated or otherwise
	 * invalidated this page.  If unmap_mapping_range got called,
	 * retry getting the page.
	 */
	if (mapping && unlikely(sequence != mapping->truncate_count)) {
2218
		pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2219
		page_cache_release(new_page);
2220 2221 2222
		cond_resched();
		sequence = mapping->truncate_count;
		smp_rmb();
L
Linus Torvalds 已提交
2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243
		goto retry;
	}

	/*
	 * 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... */
	if (pte_none(*page_table)) {
		flush_icache_page(vma, new_page);
		entry = mk_pte(new_page, vma->vm_page_prot);
		if (write_access)
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
		if (anon) {
2244
			inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2245
			lru_cache_add_active(new_page);
N
Nick Piggin 已提交
2246
			page_add_new_anon_rmap(new_page, vma, address);
2247
		} else {
2248
			inc_mm_counter(mm, file_rss);
L
Linus Torvalds 已提交
2249
			page_add_file_rmap(new_page);
2250 2251 2252 2253
			if (write_access) {
				dirty_page = new_page;
				get_page(dirty_page);
			}
2254
		}
L
Linus Torvalds 已提交
2255 2256 2257
	} else {
		/* One of our sibling threads was faster, back out. */
		page_cache_release(new_page);
2258
		goto unlock;
L
Linus Torvalds 已提交
2259 2260 2261 2262 2263
	}

	/* no need to invalidate: a not-present page shouldn't be cached */
	update_mmu_cache(vma, address, entry);
	lazy_mmu_prot_update(entry);
2264
unlock:
2265
	pte_unmap_unlock(page_table, ptl);
2266
	if (dirty_page) {
P
Peter Zijlstra 已提交
2267
		set_page_dirty_balance(dirty_page);
2268 2269
		put_page(dirty_page);
	}
L
Linus Torvalds 已提交
2270 2271 2272
	return ret;
oom:
	page_cache_release(new_page);
2273
	return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2274 2275
}

J
Jes Sorensen 已提交
2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323
/*
 * do_no_pfn() tries to create a new page mapping for a page without
 * a struct_page backing it
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
 *
 * It is expected that the ->nopfn handler always returns the same pfn
 * for a given virtual mapping.
 *
 * Mark this `noinline' to prevent it from bloating the main pagefault code.
 */
static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
		     unsigned long address, pte_t *page_table, pmd_t *pmd,
		     int write_access)
{
	spinlock_t *ptl;
	pte_t entry;
	unsigned long pfn;
	int ret = VM_FAULT_MINOR;

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

	pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
	if (pfn == NOPFN_OOM)
		return VM_FAULT_OOM;
	if (pfn == NOPFN_SIGBUS)
		return VM_FAULT_SIGBUS;

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

	/* Only go through if we didn't race with anybody else... */
	if (pte_none(*page_table)) {
		entry = pfn_pte(pfn, vma->vm_page_prot);
		if (write_access)
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		set_pte_at(mm, address, page_table, entry);
	}
	pte_unmap_unlock(page_table, ptl);
	return ret;
}

L
Linus Torvalds 已提交
2324 2325 2326 2327
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2328 2329 2330 2331
 *
 * 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
2332
 */
2333 2334 2335
static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2336
{
2337
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2338 2339
	int err;

H
Hugh Dickins 已提交
2340
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2341
		return VM_FAULT_MINOR;
L
Linus Torvalds 已提交
2342

2343 2344 2345 2346
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2347
		print_bad_pte(vma, orig_pte, address);
2348 2349 2350 2351 2352 2353 2354
		return VM_FAULT_OOM;
	}
	/* We can then assume vm->vm_ops && vma->vm_ops->populate */

	pgoff = pte_to_pgoff(orig_pte);
	err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
					vma->vm_page_prot, pgoff, 0);
L
Linus Torvalds 已提交
2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370
	if (err == -ENOMEM)
		return VM_FAULT_OOM;
	if (err)
		return VM_FAULT_SIGBUS;
	return VM_FAULT_MAJOR;
}

/*
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 *
H
Hugh Dickins 已提交
2371 2372 2373
 * 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
2374 2375
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2376 2377
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2378 2379
{
	pte_t entry;
2380
	pte_t old_entry;
2381
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2382

2383
	old_entry = entry = *pte;
L
Linus Torvalds 已提交
2384
	if (!pte_present(entry)) {
2385
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396
			if (vma->vm_ops) {
				if (vma->vm_ops->nopage)
					return do_no_page(mm, vma, address,
							  pte, pmd,
							  write_access);
				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);
2397
		}
L
Linus Torvalds 已提交
2398
		if (pte_file(entry))
2399 2400 2401 2402
			return do_file_page(mm, vma, address,
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2403 2404
	}

H
Hugh Dickins 已提交
2405
	ptl = pte_lockptr(mm, pmd);
2406 2407 2408
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2409 2410
	if (write_access) {
		if (!pte_write(entry))
2411 2412
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2413 2414 2415
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429
	if (!pte_same(old_entry, entry)) {
		ptep_set_access_flags(vma, address, pte, entry, write_access);
		update_mmu_cache(vma, address, entry);
		lazy_mmu_prot_update(entry);
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2430 2431
unlock:
	pte_unmap_unlock(pte, ptl);
L
Linus Torvalds 已提交
2432 2433 2434 2435 2436 2437
	return VM_FAULT_MINOR;
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
2438
int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2439 2440 2441 2442 2443 2444 2445 2446 2447
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2448
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2449

2450 2451
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2452 2453 2454 2455

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2456
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2457 2458
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2459
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2460 2461
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2462
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2463

H
Hugh Dickins 已提交
2464
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2465 2466
}

2467 2468
EXPORT_SYMBOL_GPL(__handle_mm_fault);

L
Linus Torvalds 已提交
2469 2470 2471
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2472
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2473
 */
2474
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2475
{
H
Hugh Dickins 已提交
2476 2477
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2478
		return -ENOMEM;
L
Linus Torvalds 已提交
2479

H
Hugh Dickins 已提交
2480
	spin_lock(&mm->page_table_lock);
2481
	if (pgd_present(*pgd))		/* Another has populated it */
L
Linus Torvalds 已提交
2482
		pud_free(new);
2483 2484
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2485
	spin_unlock(&mm->page_table_lock);
2486
	return 0;
L
Linus Torvalds 已提交
2487
}
2488 2489 2490 2491 2492 2493
#else
/* Workaround for gcc 2.96 */
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
	return 0;
}
L
Linus Torvalds 已提交
2494 2495 2496 2497 2498
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2499
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2500
 */
2501
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2502
{
H
Hugh Dickins 已提交
2503 2504
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2505
		return -ENOMEM;
L
Linus Torvalds 已提交
2506

H
Hugh Dickins 已提交
2507
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2508
#ifndef __ARCH_HAS_4LEVEL_HACK
2509
	if (pud_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2510
		pmd_free(new);
2511 2512
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2513
#else
2514
	if (pgd_present(*pud))		/* Another has populated it */
L
Linus Torvalds 已提交
2515
		pmd_free(new);
2516 2517
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2518
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2519
	spin_unlock(&mm->page_table_lock);
2520
	return 0;
2521 2522 2523 2524 2525 2526
}
#else
/* Workaround for gcc 2.96 */
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
	return 0;
L
Linus Torvalds 已提交
2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538
}
#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;
2539 2540
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
L
Linus Torvalds 已提交
2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591
	len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
	if (ret < 0)
		return ret;
	return ret == len ? 0 : -1;
}

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

EXPORT_SYMBOL(vmalloc_to_page);

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

EXPORT_SYMBOL(vmalloc_to_pfn);

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2592
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2593 2594 2595 2596 2597 2598 2599

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;
	gate_vma.vm_page_prot = PAGE_READONLY;
H
Hugh Dickins 已提交
2600
	gate_vma.vm_flags = 0;
L
Linus Torvalds 已提交
2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624
	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 */
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 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677

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

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

	down_read(&mm->mmap_sem);
	/* ignore errors, just check how much was sucessfully transfered */
	while (len) {
		int bytes, ret, offset;
		void *maddr;

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

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

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

	return buf - old_buf;
}