linux/mm/memory.c
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   1/*
   2 *  linux/mm/memory.c
   3 *
   4 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   5 */
   6
   7/*
   8 * demand-loading started 01.12.91 - seems it is high on the list of
   9 * things wanted, and it should be easy to implement. - Linus
  10 */
  11
  12/*
  13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
  14 * pages started 02.12.91, seems to work. - Linus.
  15 *
  16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
  17 * would have taken more than the 6M I have free, but it worked well as
  18 * far as I could see.
  19 *
  20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
  21 */
  22
  23/*
  24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
  25 * thought has to go into this. Oh, well..
  26 * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
  27 *              Found it. Everything seems to work now.
  28 * 20.12.91  -  Ok, making the swap-device changeable like the root.
  29 */
  30
  31/*
  32 * 05.04.94  -  Multi-page memory management added for v1.1.
  33 *              Idea by Alex Bligh (alex@cconcepts.co.uk)
  34 *
  35 * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
  36 *              (Gerhard.Wichert@pdb.siemens.de)
  37 *
  38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
  39 */
  40
  41#include <linux/kernel_stat.h>
  42#include <linux/mm.h>
  43#include <linux/hugetlb.h>
  44#include <linux/mman.h>
  45#include <linux/swap.h>
  46#include <linux/highmem.h>
  47#include <linux/pagemap.h>
  48#include <linux/ksm.h>
  49#include <linux/rmap.h>
  50#include <linux/module.h>
  51#include <linux/delayacct.h>
  52#include <linux/init.h>
  53#include <linux/writeback.h>
  54#include <linux/memcontrol.h>
  55#include <linux/mmu_notifier.h>
  56#include <linux/kallsyms.h>
  57#include <linux/swapops.h>
  58#include <linux/elf.h>
  59#include <linux/gfp.h>
  60
  61#include <asm/io.h>
  62#include <asm/pgalloc.h>
  63#include <asm/uaccess.h>
  64#include <asm/tlb.h>
  65#include <asm/tlbflush.h>
  66#include <asm/pgtable.h>
  67
  68#include "internal.h"
  69
  70#ifndef CONFIG_NEED_MULTIPLE_NODES
  71/* use the per-pgdat data instead for discontigmem - mbligh */
  72unsigned long max_mapnr;
  73struct page *mem_map;
  74
  75EXPORT_SYMBOL(max_mapnr);
  76EXPORT_SYMBOL(mem_map);
  77#endif
  78
  79unsigned long num_physpages;
  80/*
  81 * A number of key systems in x86 including ioremap() rely on the assumption
  82 * that high_memory defines the upper bound on direct map memory, then end
  83 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
  84 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
  85 * and ZONE_HIGHMEM.
  86 */
  87void * high_memory;
  88
  89EXPORT_SYMBOL(num_physpages);
  90EXPORT_SYMBOL(high_memory);
  91
  92/*
  93 * Randomize the address space (stacks, mmaps, brk, etc.).
  94 *
  95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
  96 *   as ancient (libc5 based) binaries can segfault. )
  97 */
  98int randomize_va_space __read_mostly =
  99#ifdef CONFIG_COMPAT_BRK
 100                                        1;
 101#else
 102                                        2;
 103#endif
 104
 105static int __init disable_randmaps(char *s)
 106{
 107        randomize_va_space = 0;
 108        return 1;
 109}
 110__setup("norandmaps", disable_randmaps);
 111
 112unsigned long zero_pfn __read_mostly;
 113unsigned long highest_memmap_pfn __read_mostly;
 114
 115/*
 116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
 117 */
 118static int __init init_zero_pfn(void)
 119{
 120        zero_pfn = page_to_pfn(ZERO_PAGE(0));
 121        return 0;
 122}
 123core_initcall(init_zero_pfn);
 124
 125
 126#if defined(SPLIT_RSS_COUNTING)
 127
 128static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
 129{
 130        int i;
 131
 132        for (i = 0; i < NR_MM_COUNTERS; i++) {
 133                if (task->rss_stat.count[i]) {
 134                        add_mm_counter(mm, i, task->rss_stat.count[i]);
 135                        task->rss_stat.count[i] = 0;
 136                }
 137        }
 138        task->rss_stat.events = 0;
 139}
 140
 141static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
 142{
 143        struct task_struct *task = current;
 144
 145        if (likely(task->mm == mm))
 146                task->rss_stat.count[member] += val;
 147        else
 148                add_mm_counter(mm, member, val);
 149}
 150#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
 151#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
 152
 153/* sync counter once per 64 page faults */
 154#define TASK_RSS_EVENTS_THRESH  (64)
 155static void check_sync_rss_stat(struct task_struct *task)
 156{
 157        if (unlikely(task != current))
 158                return;
 159        if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
 160                __sync_task_rss_stat(task, task->mm);
 161}
 162
 163unsigned long get_mm_counter(struct mm_struct *mm, int member)
 164{
 165        long val = 0;
 166
 167        /*
 168         * Don't use task->mm here...for avoiding to use task_get_mm()..
 169         * The caller must guarantee task->mm is not invalid.
 170         */
 171        val = atomic_long_read(&mm->rss_stat.count[member]);
 172        /*
 173         * counter is updated in asynchronous manner and may go to minus.
 174         * But it's never be expected number for users.
 175         */
 176        if (val < 0)
 177                return 0;
 178        return (unsigned long)val;
 179}
 180
 181void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
 182{
 183        __sync_task_rss_stat(task, mm);
 184}
 185#else /* SPLIT_RSS_COUNTING */
 186
 187#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
 188#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
 189
 190static void check_sync_rss_stat(struct task_struct *task)
 191{
 192}
 193
 194#endif /* SPLIT_RSS_COUNTING */
 195
 196#ifdef HAVE_GENERIC_MMU_GATHER
 197
 198static int tlb_next_batch(struct mmu_gather *tlb)
 199{
 200        struct mmu_gather_batch *batch;
 201
 202        batch = tlb->active;
 203        if (batch->next) {
 204                tlb->active = batch->next;
 205                return 1;
 206        }
 207
 208        batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
 209        if (!batch)
 210                return 0;
 211
 212        batch->next = NULL;
 213        batch->nr   = 0;
 214        batch->max  = MAX_GATHER_BATCH;
 215
 216        tlb->active->next = batch;
 217        tlb->active = batch;
 218
 219        return 1;
 220}
 221
 222/* tlb_gather_mmu
 223 *      Called to initialize an (on-stack) mmu_gather structure for page-table
 224 *      tear-down from @mm. The @fullmm argument is used when @mm is without
 225 *      users and we're going to destroy the full address space (exit/execve).
 226 */
 227void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
 228{
 229        tlb->mm = mm;
 230
 231        tlb->fullmm     = fullmm;
 232        tlb->need_flush = 0;
 233        tlb->fast_mode  = (num_possible_cpus() == 1);
 234        tlb->local.next = NULL;
 235        tlb->local.nr   = 0;
 236        tlb->local.max  = ARRAY_SIZE(tlb->__pages);
 237        tlb->active     = &tlb->local;
 238
 239#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 240        tlb->batch = NULL;
 241#endif
 242}
 243
 244void tlb_flush_mmu(struct mmu_gather *tlb)
 245{
 246        struct mmu_gather_batch *batch;
 247
 248        if (!tlb->need_flush)
 249                return;
 250        tlb->need_flush = 0;
 251        tlb_flush(tlb);
 252#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 253        tlb_table_flush(tlb);
 254#endif
 255
 256        if (tlb_fast_mode(tlb))
 257                return;
 258
 259        for (batch = &tlb->local; batch; batch = batch->next) {
 260                free_pages_and_swap_cache(batch->pages, batch->nr);
 261                batch->nr = 0;
 262        }
 263        tlb->active = &tlb->local;
 264}
 265
 266/* tlb_finish_mmu
 267 *      Called at the end of the shootdown operation to free up any resources
 268 *      that were required.
 269 */
 270void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 271{
 272        struct mmu_gather_batch *batch, *next;
 273
 274        tlb_flush_mmu(tlb);
 275
 276        /* keep the page table cache within bounds */
 277        check_pgt_cache();
 278
 279        for (batch = tlb->local.next; batch; batch = next) {
 280                next = batch->next;
 281                free_pages((unsigned long)batch, 0);
 282        }
 283        tlb->local.next = NULL;
 284}
 285
 286/* __tlb_remove_page
 287 *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
 288 *      handling the additional races in SMP caused by other CPUs caching valid
 289 *      mappings in their TLBs. Returns the number of free page slots left.
 290 *      When out of page slots we must call tlb_flush_mmu().
 291 */
 292int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 293{
 294        struct mmu_gather_batch *batch;
 295
 296        tlb->need_flush = 1;
 297
 298        if (tlb_fast_mode(tlb)) {
 299                free_page_and_swap_cache(page);
 300                return 1; /* avoid calling tlb_flush_mmu() */
 301        }
 302
 303        batch = tlb->active;
 304        batch->pages[batch->nr++] = page;
 305        if (batch->nr == batch->max) {
 306                if (!tlb_next_batch(tlb))
 307                        return 0;
 308                batch = tlb->active;
 309        }
 310        VM_BUG_ON(batch->nr > batch->max);
 311
 312        return batch->max - batch->nr;
 313}
 314
 315#endif /* HAVE_GENERIC_MMU_GATHER */
 316
 317#ifdef CONFIG_HAVE_RCU_TABLE_FREE
 318
 319/*
 320 * See the comment near struct mmu_table_batch.
 321 */
 322
 323static void tlb_remove_table_smp_sync(void *arg)
 324{
 325        /* Simply deliver the interrupt */
 326}
 327
 328static void tlb_remove_table_one(void *table)
 329{
 330        /*
 331         * This isn't an RCU grace period and hence the page-tables cannot be
 332         * assumed to be actually RCU-freed.
 333         *
 334         * It is however sufficient for software page-table walkers that rely on
 335         * IRQ disabling. See the comment near struct mmu_table_batch.
 336         */
 337        smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
 338        __tlb_remove_table(table);
 339}
 340
 341static void tlb_remove_table_rcu(struct rcu_head *head)
 342{
 343        struct mmu_table_batch *batch;
 344        int i;
 345
 346        batch = container_of(head, struct mmu_table_batch, rcu);
 347
 348        for (i = 0; i < batch->nr; i++)
 349                __tlb_remove_table(batch->tables[i]);
 350
 351        free_page((unsigned long)batch);
 352}
 353
 354void tlb_table_flush(struct mmu_gather *tlb)
 355{
 356        struct mmu_table_batch **batch = &tlb->batch;
 357
 358        if (*batch) {
 359                call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
 360                *batch = NULL;
 361        }
 362}
 363
 364void tlb_remove_table(struct mmu_gather *tlb, void *table)
 365{
 366        struct mmu_table_batch **batch = &tlb->batch;
 367
 368        tlb->need_flush = 1;
 369
 370        /*
 371         * When there's less then two users of this mm there cannot be a
 372         * concurrent page-table walk.
 373         */
 374        if (atomic_read(&tlb->mm->mm_users) < 2) {
 375                __tlb_remove_table(table);
 376                return;
 377        }
 378
 379        if (*batch == NULL) {
 380                *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
 381                if (*batch == NULL) {
 382                        tlb_remove_table_one(table);
 383                        return;
 384                }
 385                (*batch)->nr = 0;
 386        }
 387        (*batch)->tables[(*batch)->nr++] = table;
 388        if ((*batch)->nr == MAX_TABLE_BATCH)
 389                tlb_table_flush(tlb);
 390}
 391
 392#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
 393
 394/*
 395 * If a p?d_bad entry is found while walking page tables, report
 396 * the error, before resetting entry to p?d_none.  Usually (but
 397 * very seldom) called out from the p?d_none_or_clear_bad macros.
 398 */
 399
 400void pgd_clear_bad(pgd_t *pgd)
 401{
 402        pgd_ERROR(*pgd);
 403        pgd_clear(pgd);
 404}
 405
 406void pud_clear_bad(pud_t *pud)
 407{
 408        pud_ERROR(*pud);
 409        pud_clear(pud);
 410}
 411
 412void pmd_clear_bad(pmd_t *pmd)
 413{
 414        pmd_ERROR(*pmd);
 415        pmd_clear(pmd);
 416}
 417
 418/*
 419 * Note: this doesn't free the actual pages themselves. That
 420 * has been handled earlier when unmapping all the memory regions.
 421 */
 422static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 423                           unsigned long addr)
 424{
 425        pgtable_t token = pmd_pgtable(*pmd);
 426        pmd_clear(pmd);
 427        pte_free_tlb(tlb, token, addr);
 428        tlb->mm->nr_ptes--;
 429}
 430
 431static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 432                                unsigned long addr, unsigned long end,
 433                                unsigned long floor, unsigned long ceiling)
 434{
 435        pmd_t *pmd;
 436        unsigned long next;
 437        unsigned long start;
 438
 439        start = addr;
 440        pmd = pmd_offset(pud, addr);
 441        do {
 442                next = pmd_addr_end(addr, end);
 443                if (pmd_none_or_clear_bad(pmd))
 444                        continue;
 445                free_pte_range(tlb, pmd, addr);
 446        } while (pmd++, addr = next, addr != end);
 447
 448        start &= PUD_MASK;
 449        if (start < floor)
 450                return;
 451        if (ceiling) {
 452                ceiling &= PUD_MASK;
 453                if (!ceiling)
 454                        return;
 455        }
 456        if (end - 1 > ceiling - 1)
 457                return;
 458
 459        pmd = pmd_offset(pud, start);
 460        pud_clear(pud);
 461        pmd_free_tlb(tlb, pmd, start);
 462}
 463
 464static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 465                                unsigned long addr, unsigned long end,
 466                                unsigned long floor, unsigned long ceiling)
 467{
 468        pud_t *pud;
 469        unsigned long next;
 470        unsigned long start;
 471
 472        start = addr;
 473        pud = pud_offset(pgd, addr);
 474        do {
 475                next = pud_addr_end(addr, end);
 476                if (pud_none_or_clear_bad(pud))
 477                        continue;
 478                free_pmd_range(tlb, pud, addr, next, floor, ceiling);
 479        } while (pud++, addr = next, addr != end);
 480
 481        start &= PGDIR_MASK;
 482        if (start < floor)
 483                return;
 484        if (ceiling) {
 485                ceiling &= PGDIR_MASK;
 486                if (!ceiling)
 487                        return;
 488        }
 489        if (end - 1 > ceiling - 1)
 490                return;
 491
 492        pud = pud_offset(pgd, start);
 493        pgd_clear(pgd);
 494        pud_free_tlb(tlb, pud, start);
 495}
 496
 497/*
 498 * This function frees user-level page tables of a process.
 499 *
 500 * Must be called with pagetable lock held.
 501 */
 502void free_pgd_range(struct mmu_gather *tlb,
 503                        unsigned long addr, unsigned long end,
 504                        unsigned long floor, unsigned long ceiling)
 505{
 506        pgd_t *pgd;
 507        unsigned long next;
 508
 509        /*
 510         * The next few lines have given us lots of grief...
 511         *
 512         * Why are we testing PMD* at this top level?  Because often
 513         * there will be no work to do at all, and we'd prefer not to
 514         * go all the way down to the bottom just to discover that.
 515         *
 516         * Why all these "- 1"s?  Because 0 represents both the bottom
 517         * of the address space and the top of it (using -1 for the
 518         * top wouldn't help much: the masks would do the wrong thing).
 519         * The rule is that addr 0 and floor 0 refer to the bottom of
 520         * the address space, but end 0 and ceiling 0 refer to the top
 521         * Comparisons need to use "end - 1" and "ceiling - 1" (though
 522         * that end 0 case should be mythical).
 523         *
 524         * Wherever addr is brought up or ceiling brought down, we must
 525         * be careful to reject "the opposite 0" before it confuses the
 526         * subsequent tests.  But what about where end is brought down
 527         * by PMD_SIZE below? no, end can't go down to 0 there.
 528         *
 529         * Whereas we round start (addr) and ceiling down, by different
 530         * masks at different levels, in order to test whether a table
 531         * now has no other vmas using it, so can be freed, we don't
 532         * bother to round floor or end up - the tests don't need that.
 533         */
 534
 535        addr &= PMD_MASK;
 536        if (addr < floor) {
 537                addr += PMD_SIZE;
 538                if (!addr)
 539                        return;
 540        }
 541        if (ceiling) {
 542                ceiling &= PMD_MASK;
 543                if (!ceiling)
 544                        return;
 545        }
 546        if (end - 1 > ceiling - 1)
 547                end -= PMD_SIZE;
 548        if (addr > end - 1)
 549                return;
 550
 551        pgd = pgd_offset(tlb->mm, addr);
 552        do {
 553                next = pgd_addr_end(addr, end);
 554                if (pgd_none_or_clear_bad(pgd))
 555                        continue;
 556                free_pud_range(tlb, pgd, addr, next, floor, ceiling);
 557        } while (pgd++, addr = next, addr != end);
 558}
 559
 560void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 561                unsigned long floor, unsigned long ceiling)
 562{
 563        while (vma) {
 564                struct vm_area_struct *next = vma->vm_next;
 565                unsigned long addr = vma->vm_start;
 566
 567                /*
 568                 * Hide vma from rmap and truncate_pagecache before freeing
 569                 * pgtables
 570                 */
 571                unlink_anon_vmas(vma);
 572                unlink_file_vma(vma);
 573
 574                if (is_vm_hugetlb_page(vma)) {
 575                        hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
 576                                floor, next? next->vm_start: ceiling);
 577                } else {
 578                        /*
 579                         * Optimization: gather nearby vmas into one call down
 580                         */
 581                        while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 582                               && !is_vm_hugetlb_page(next)) {
 583                                vma = next;
 584                                next = vma->vm_next;
 585                                unlink_anon_vmas(vma);
 586                                unlink_file_vma(vma);
 587                        }
 588                        free_pgd_range(tlb, addr, vma->vm_end,
 589                                floor, next? next->vm_start: ceiling);
 590                }
 591                vma = next;
 592        }
 593}
 594
 595int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 596                pmd_t *pmd, unsigned long address)
 597{
 598        pgtable_t new = pte_alloc_one(mm, address);
 599        int wait_split_huge_page;
 600        if (!new)
 601                return -ENOMEM;
 602
 603        /*
 604         * Ensure all pte setup (eg. pte page lock and page clearing) are
 605         * visible before the pte is made visible to other CPUs by being
 606         * put into page tables.
 607         *
 608         * The other side of the story is the pointer chasing in the page
 609         * table walking code (when walking the page table without locking;
 610         * ie. most of the time). Fortunately, these data accesses consist
 611         * of a chain of data-dependent loads, meaning most CPUs (alpha
 612         * being the notable exception) will already guarantee loads are
 613         * seen in-order. See the alpha page table accessors for the
 614         * smp_read_barrier_depends() barriers in page table walking code.
 615         */
 616        smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
 617
 618        spin_lock(&mm->page_table_lock);
 619        wait_split_huge_page = 0;
 620        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 621                mm->nr_ptes++;
 622                pmd_populate(mm, pmd, new);
 623                new = NULL;
 624        } else if (unlikely(pmd_trans_splitting(*pmd)))
 625                wait_split_huge_page = 1;
 626        spin_unlock(&mm->page_table_lock);
 627        if (new)
 628                pte_free(mm, new);
 629        if (wait_split_huge_page)
 630                wait_split_huge_page(vma->anon_vma, pmd);
 631        return 0;
 632}
 633
 634int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
 635{
 636        pte_t *new = pte_alloc_one_kernel(&init_mm, address);
 637        if (!new)
 638                return -ENOMEM;
 639
 640        smp_wmb(); /* See comment in __pte_alloc */
 641
 642        spin_lock(&init_mm.page_table_lock);
 643        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
 644                pmd_populate_kernel(&init_mm, pmd, new);
 645                new = NULL;
 646        } else
 647                VM_BUG_ON(pmd_trans_splitting(*pmd));
 648        spin_unlock(&init_mm.page_table_lock);
 649        if (new)
 650                pte_free_kernel(&init_mm, new);
 651        return 0;
 652}
 653
 654static inline void init_rss_vec(int *rss)
 655{
 656        memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
 657}
 658
 659static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
 660{
 661        int i;
 662
 663        if (current->mm == mm)
 664                sync_mm_rss(current, mm);
 665        for (i = 0; i < NR_MM_COUNTERS; i++)
 666                if (rss[i])
 667                        add_mm_counter(mm, i, rss[i]);
 668}
 669
 670/*
 671 * This function is called to print an error when a bad pte
 672 * is found. For example, we might have a PFN-mapped pte in
 673 * a region that doesn't allow it.
 674 *
 675 * The calling function must still handle the error.
 676 */
 677static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 678                          pte_t pte, struct page *page)
 679{
 680        pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
 681        pud_t *pud = pud_offset(pgd, addr);
 682        pmd_t *pmd = pmd_offset(pud, addr);
 683        struct address_space *mapping;
 684        pgoff_t index;
 685        static unsigned long resume;
 686        static unsigned long nr_shown;
 687        static unsigned long nr_unshown;
 688
 689        /*
 690         * Allow a burst of 60 reports, then keep quiet for that minute;
 691         * or allow a steady drip of one report per second.
 692         */
 693        if (nr_shown == 60) {
 694                if (time_before(jiffies, resume)) {
 695                        nr_unshown++;
 696                        return;
 697                }
 698                if (nr_unshown) {
 699                        printk(KERN_ALERT
 700                                "BUG: Bad page map: %lu messages suppressed\n",
 701                                nr_unshown);
 702                        nr_unshown = 0;
 703                }
 704                nr_shown = 0;
 705        }
 706        if (nr_shown++ == 0)
 707                resume = jiffies + 60 * HZ;
 708
 709        mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
 710        index = linear_page_index(vma, addr);
 711
 712        printk(KERN_ALERT
 713                "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
 714                current->comm,
 715                (long long)pte_val(pte), (long long)pmd_val(*pmd));
 716        if (page)
 717                dump_page(page);
 718        printk(KERN_ALERT
 719                "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
 720                (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
 721        /*
 722         * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
 723         */
 724        if (vma->vm_ops)
 725                print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
 726                                (unsigned long)vma->vm_ops->fault);
 727        if (vma->vm_file && vma->vm_file->f_op)
 728                print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
 729                                (unsigned long)vma->vm_file->f_op->mmap);
 730        dump_stack();
 731        add_taint(TAINT_BAD_PAGE);
 732}
 733
 734static inline int is_cow_mapping(vm_flags_t flags)
 735{
 736        return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 737}
 738
 739#ifndef is_zero_pfn
 740static inline int is_zero_pfn(unsigned long pfn)
 741{
 742        return pfn == zero_pfn;
 743}
 744#endif
 745
 746#ifndef my_zero_pfn
 747static inline unsigned long my_zero_pfn(unsigned long addr)
 748{
 749        return zero_pfn;
 750}
 751#endif
 752
 753/*
 754 * vm_normal_page -- This function gets the "struct page" associated with a pte.
 755 *
 756 * "Special" mappings do not wish to be associated with a "struct page" (either
 757 * it doesn't exist, or it exists but they don't want to touch it). In this
 758 * case, NULL is returned here. "Normal" mappings do have a struct page.
 759 *
 760 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 761 * pte bit, in which case this function is trivial. Secondly, an architecture
 762 * may not have a spare pte bit, which requires a more complicated scheme,
 763 * described below.
 764 *
 765 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 766 * special mapping (even if there are underlying and valid "struct pages").
 767 * COWed pages of a VM_PFNMAP are always normal.
 768 *
 769 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 770 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
 771 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 772 * mapping will always honor the rule
 773 *
 774 *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 775 *
 776 * And for normal mappings this is false.
 777 *
 778 * This restricts such mappings to be a linear translation from virtual address
 779 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 780 * as the vma is not a COW mapping; in that case, we know that all ptes are
 781 * special (because none can have been COWed).
 782 *
 783 *
 784 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
 785 *
 786 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 787 * page" backing, however the difference is that _all_ pages with a struct
 788 * page (that is, those where pfn_valid is true) are refcounted and considered
 789 * normal pages by the VM. The disadvantage is that pages are refcounted
 790 * (which can be slower and simply not an option for some PFNMAP users). The
 791 * advantage is that we don't have to follow the strict linearity rule of
 792 * PFNMAP mappings in order to support COWable mappings.
 793 *
 794 */
 795#ifdef __HAVE_ARCH_PTE_SPECIAL
 796# define HAVE_PTE_SPECIAL 1
 797#else
 798# define HAVE_PTE_SPECIAL 0
 799#endif
 800struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
 801                                pte_t pte)
 802{
 803        unsigned long pfn = pte_pfn(pte);
 804
 805        if (HAVE_PTE_SPECIAL) {
 806                if (likely(!pte_special(pte)))
 807                        goto check_pfn;
 808                if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
 809                        return NULL;
 810                if (!is_zero_pfn(pfn))
 811                        print_bad_pte(vma, addr, pte, NULL);
 812                return NULL;
 813        }
 814
 815        /* !HAVE_PTE_SPECIAL case follows: */
 816
 817        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
 818                if (vma->vm_flags & VM_MIXEDMAP) {
 819                        if (!pfn_valid(pfn))
 820                                return NULL;
 821                        goto out;
 822                } else {
 823                        unsigned long off;
 824                        off = (addr - vma->vm_start) >> PAGE_SHIFT;
 825                        if (pfn == vma->vm_pgoff + off)
 826                                return NULL;
 827                        if (!is_cow_mapping(vma->vm_flags))
 828                                return NULL;
 829                }
 830        }
 831
 832        if (is_zero_pfn(pfn))
 833                return NULL;
 834check_pfn:
 835        if (unlikely(pfn > highest_memmap_pfn)) {
 836                print_bad_pte(vma, addr, pte, NULL);
 837                return NULL;
 838        }
 839
 840        /*
 841         * NOTE! We still have PageReserved() pages in the page tables.
 842         * eg. VDSO mappings can cause them to exist.
 843         */
 844out:
 845        return pfn_to_page(pfn);
 846}
 847
 848/*
 849 * copy one vm_area from one task to the other. Assumes the page tables
 850 * already present in the new task to be cleared in the whole range
 851 * covered by this vma.
 852 */
 853
 854static inline unsigned long
 855copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 856                pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
 857                unsigned long addr, int *rss)
 858{
 859        unsigned long vm_flags = vma->vm_flags;
 860        pte_t pte = *src_pte;
 861        struct page *page;
 862
 863        /* pte contains position in swap or file, so copy. */
 864        if (unlikely(!pte_present(pte))) {
 865                if (!pte_file(pte)) {
 866                        swp_entry_t entry = pte_to_swp_entry(pte);
 867
 868                        if (swap_duplicate(entry) < 0)
 869                                return entry.val;
 870
 871                        /* make sure dst_mm is on swapoff's mmlist. */
 872                        if (unlikely(list_empty(&dst_mm->mmlist))) {
 873                                spin_lock(&mmlist_lock);
 874                                if (list_empty(&dst_mm->mmlist))
 875                                        list_add(&dst_mm->mmlist,
 876                                                 &src_mm->mmlist);
 877                                spin_unlock(&mmlist_lock);
 878                        }
 879                        if (likely(!non_swap_entry(entry)))
 880                                rss[MM_SWAPENTS]++;
 881                        else if (is_write_migration_entry(entry) &&
 882                                        is_cow_mapping(vm_flags)) {
 883                                /*
 884                                 * COW mappings require pages in both parent
 885                                 * and child to be set to read.
 886                                 */
 887                                make_migration_entry_read(&entry);
 888                                pte = swp_entry_to_pte(entry);
 889                                set_pte_at(src_mm, addr, src_pte, pte);
 890                        }
 891                }
 892                goto out_set_pte;
 893        }
 894
 895        /*
 896         * If it's a COW mapping, write protect it both
 897         * in the parent and the child
 898         */
 899        if (is_cow_mapping(vm_flags)) {
 900                ptep_set_wrprotect(src_mm, addr, src_pte);
 901                pte = pte_wrprotect(pte);
 902        }
 903
 904        /*
 905         * If it's a shared mapping, mark it clean in
 906         * the child
 907         */
 908        if (vm_flags & VM_SHARED)
 909                pte = pte_mkclean(pte);
 910        pte = pte_mkold(pte);
 911
 912        page = vm_normal_page(vma, addr, pte);
 913        if (page) {
 914                get_page(page);
 915                page_dup_rmap(page);
 916                if (PageAnon(page))
 917                        rss[MM_ANONPAGES]++;
 918                else
 919                        rss[MM_FILEPAGES]++;
 920        }
 921
 922out_set_pte:
 923        set_pte_at(dst_mm, addr, dst_pte, pte);
 924        return 0;
 925}
 926
 927int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 928                   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
 929                   unsigned long addr, unsigned long end)
 930{
 931        pte_t *orig_src_pte, *orig_dst_pte;
 932        pte_t *src_pte, *dst_pte;
 933        spinlock_t *src_ptl, *dst_ptl;
 934        int progress = 0;
 935        int rss[NR_MM_COUNTERS];
 936        swp_entry_t entry = (swp_entry_t){0};
 937
 938again:
 939        init_rss_vec(rss);
 940
 941        dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
 942        if (!dst_pte)
 943                return -ENOMEM;
 944        src_pte = pte_offset_map(src_pmd, addr);
 945        src_ptl = pte_lockptr(src_mm, src_pmd);
 946        spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 947        orig_src_pte = src_pte;
 948        orig_dst_pte = dst_pte;
 949        arch_enter_lazy_mmu_mode();
 950
 951        do {
 952                /*
 953                 * We are holding two locks at this point - either of them
 954                 * could generate latencies in another task on another CPU.
 955                 */
 956                if (progress >= 32) {
 957                        progress = 0;
 958                        if (need_resched() ||
 959                            spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
 960                                break;
 961                }
 962                if (pte_none(*src_pte)) {
 963                        progress++;
 964                        continue;
 965                }
 966                entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
 967                                                        vma, addr, rss);
 968                if (entry.val)
 969                        break;
 970                progress += 8;
 971        } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 972
 973        arch_leave_lazy_mmu_mode();
 974        spin_unlock(src_ptl);
 975        pte_unmap(orig_src_pte);
 976        add_mm_rss_vec(dst_mm, rss);
 977        pte_unmap_unlock(orig_dst_pte, dst_ptl);
 978        cond_resched();
 979
 980        if (entry.val) {
 981                if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
 982                        return -ENOMEM;
 983                progress = 0;
 984        }
 985        if (addr != end)
 986                goto again;
 987        return 0;
 988}
 989
 990static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 991                pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
 992                unsigned long addr, unsigned long end)
 993{
 994        pmd_t *src_pmd, *dst_pmd;
 995        unsigned long next;
 996
 997        dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
 998        if (!dst_pmd)
 999                return -ENOMEM;
1000        src_pmd = pmd_offset(src_pud, addr);
1001        do {
1002                next = pmd_addr_end(addr, end);
1003                if (pmd_trans_huge(*src_pmd)) {
1004                        int err;
1005                        VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1006                        err = copy_huge_pmd(dst_mm, src_mm,
1007                                            dst_pmd, src_pmd, addr, vma);
1008                        if (err == -ENOMEM)
1009                                return -ENOMEM;
1010                        if (!err)
1011                                continue;
1012                        /* fall through */
1013                }
1014                if (pmd_none_or_clear_bad(src_pmd))
1015                        continue;
1016                if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1017                                                vma, addr, next))
1018                        return -ENOMEM;
1019        } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1020        return 0;
1021}
1022
1023static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1024                pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1025                unsigned long addr, unsigned long end)
1026{
1027        pud_t *src_pud, *dst_pud;
1028        unsigned long next;
1029
1030        dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1031        if (!dst_pud)
1032                return -ENOMEM;
1033        src_pud = pud_offset(src_pgd, addr);
1034        do {
1035                next = pud_addr_end(addr, end);
1036                if (pud_none_or_clear_bad(src_pud))
1037                        continue;
1038                if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1039                                                vma, addr, next))
1040                        return -ENOMEM;
1041        } while (dst_pud++, src_pud++, addr = next, addr != end);
1042        return 0;
1043}
1044
1045int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046                struct vm_area_struct *vma)
1047{
1048        pgd_t *src_pgd, *dst_pgd;
1049        unsigned long next;
1050        unsigned long addr = vma->vm_start;
1051        unsigned long end = vma->vm_end;
1052        int ret;
1053
1054        /*
1055         * Don't copy ptes where a page fault will fill them correctly.
1056         * Fork becomes much lighter when there are big shared or private
1057         * readonly mappings. The tradeoff is that copy_page_range is more
1058         * efficient than faulting.
1059         */
1060        if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1061                if (!vma->anon_vma)
1062                        return 0;
1063        }
1064
1065        if (is_vm_hugetlb_page(vma))
1066                return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1067
1068        if (unlikely(is_pfn_mapping(vma))) {
1069                /*
1070                 * We do not free on error cases below as remove_vma
1071                 * gets called on error from higher level routine
1072                 */
1073                ret = track_pfn_vma_copy(vma);
1074                if (ret)
1075                        return ret;
1076        }
1077
1078        /*
1079         * We need to invalidate the secondary MMU mappings only when
1080         * there could be a permission downgrade on the ptes of the
1081         * parent mm. And a permission downgrade will only happen if
1082         * is_cow_mapping() returns true.
1083         */
1084        if (is_cow_mapping(vma->vm_flags))
1085                mmu_notifier_invalidate_range_start(src_mm, addr, end);
1086
1087        ret = 0;
1088        dst_pgd = pgd_offset(dst_mm, addr);
1089        src_pgd = pgd_offset(src_mm, addr);
1090        do {
1091                next = pgd_addr_end(addr, end);
1092                if (pgd_none_or_clear_bad(src_pgd))
1093                        continue;
1094                if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1095                                            vma, addr, next))) {
1096                        ret = -ENOMEM;
1097                        break;
1098                }
1099        } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1100
1101        if (is_cow_mapping(vma->vm_flags))
1102                mmu_notifier_invalidate_range_end(src_mm,
1103                                                  vma->vm_start, end);
1104        return ret;
1105}
1106
1107static unsigned long zap_pte_range(struct mmu_gather *tlb,
1108                                struct vm_area_struct *vma, pmd_t *pmd,
1109                                unsigned long addr, unsigned long end,
1110                                struct zap_details *details)
1111{
1112        struct mm_struct *mm = tlb->mm;
1113        int force_flush = 0;
1114        int rss[NR_MM_COUNTERS];
1115        spinlock_t *ptl;
1116        pte_t *start_pte;
1117        pte_t *pte;
1118
1119again:
1120        init_rss_vec(rss);
1121        start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1122        pte = start_pte;
1123        arch_enter_lazy_mmu_mode();
1124        do {
1125                pte_t ptent = *pte;
1126                if (pte_none(ptent)) {
1127                        continue;
1128                }
1129
1130                if (pte_present(ptent)) {
1131                        struct page *page;
1132
1133                        page = vm_normal_page(vma, addr, ptent);
1134                        if (unlikely(details) && page) {
1135                                /*
1136                                 * unmap_shared_mapping_pages() wants to
1137                                 * invalidate cache without truncating:
1138                                 * unmap shared but keep private pages.
1139                                 */
1140                                if (details->check_mapping &&
1141                                    details->check_mapping != page->mapping)
1142                                        continue;
1143                                /*
1144                                 * Each page->index must be checked when
1145                                 * invalidating or truncating nonlinear.
1146                                 */
1147                                if (details->nonlinear_vma &&
1148                                    (page->index < details->first_index ||
1149                                     page->index > details->last_index))
1150                                        continue;
1151                        }
1152                        ptent = ptep_get_and_clear_full(mm, addr, pte,
1153                                                        tlb->fullmm);
1154                        tlb_remove_tlb_entry(tlb, pte, addr);
1155                        if (unlikely(!page))
1156                                continue;
1157                        if (unlikely(details) && details->nonlinear_vma
1158                            && linear_page_index(details->nonlinear_vma,
1159                                                addr) != page->index)
1160                                set_pte_at(mm, addr, pte,
1161                                           pgoff_to_pte(page->index));
1162                        if (PageAnon(page))
1163                                rss[MM_ANONPAGES]--;
1164                        else {
1165                                if (pte_dirty(ptent))
1166                                        set_page_dirty(page);
1167                                if (pte_young(ptent) &&
1168                                    likely(!VM_SequentialReadHint(vma)))
1169                                        mark_page_accessed(page);
1170                                rss[MM_FILEPAGES]--;
1171                        }
1172                        page_remove_rmap(page);
1173                        if (unlikely(page_mapcount(page) < 0))
1174                                print_bad_pte(vma, addr, ptent, page);
1175                        force_flush = !__tlb_remove_page(tlb, page);
1176                        if (force_flush)
1177                                break;
1178                        continue;
1179                }
1180                /*
1181                 * If details->check_mapping, we leave swap entries;
1182                 * if details->nonlinear_vma, we leave file entries.
1183                 */
1184                if (unlikely(details))
1185                        continue;
1186                if (pte_file(ptent)) {
1187                        if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1188                                print_bad_pte(vma, addr, ptent, NULL);
1189                } else {
1190                        swp_entry_t entry = pte_to_swp_entry(ptent);
1191
1192                        if (!non_swap_entry(entry))
1193                                rss[MM_SWAPENTS]--;
1194                        if (unlikely(!free_swap_and_cache(entry)))
1195                                print_bad_pte(vma, addr, ptent, NULL);
1196                }
1197                pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198        } while (pte++, addr += PAGE_SIZE, addr != end);
1199
1200        add_mm_rss_vec(mm, rss);
1201        arch_leave_lazy_mmu_mode();
1202        pte_unmap_unlock(start_pte, ptl);
1203
1204        /*
1205         * mmu_gather ran out of room to batch pages, we break out of
1206         * the PTE lock to avoid doing the potential expensive TLB invalidate
1207         * and page-free while holding it.
1208         */
1209        if (force_flush) {
1210                force_flush = 0;
1211                tlb_flush_mmu(tlb);
1212                if (addr != end)
1213                        goto again;
1214        }
1215
1216        return addr;
1217}
1218
1219static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1220                                struct vm_area_struct *vma, pud_t *pud,
1221                                unsigned long addr, unsigned long end,
1222                                struct zap_details *details)
1223{
1224        pmd_t *pmd;
1225        unsigned long next;
1226
1227        pmd = pmd_offset(pud, addr);
1228        do {
1229                next = pmd_addr_end(addr, end);
1230                if (pmd_trans_huge(*pmd)) {
1231                        if (next-addr != HPAGE_PMD_SIZE) {
1232                                VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1233                                split_huge_page_pmd(vma->vm_mm, pmd);
1234                        } else if (zap_huge_pmd(tlb, vma, pmd))
1235                                continue;
1236                        /* fall through */
1237                }
1238                if (pmd_none_or_clear_bad(pmd))
1239                        continue;
1240                next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1241                cond_resched();
1242        } while (pmd++, addr = next, addr != end);
1243
1244        return addr;
1245}
1246
1247static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1248                                struct vm_area_struct *vma, pgd_t *pgd,
1249                                unsigned long addr, unsigned long end,
1250                                struct zap_details *details)
1251{
1252        pud_t *pud;
1253        unsigned long next;
1254
1255        pud = pud_offset(pgd, addr);
1256        do {
1257                next = pud_addr_end(addr, end);
1258                if (pud_none_or_clear_bad(pud))
1259                        continue;
1260                next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1261        } while (pud++, addr = next, addr != end);
1262
1263        return addr;
1264}
1265
1266static unsigned long unmap_page_range(struct mmu_gather *tlb,
1267                                struct vm_area_struct *vma,
1268                                unsigned long addr, unsigned long end,
1269                                struct zap_details *details)
1270{
1271        pgd_t *pgd;
1272        unsigned long next;
1273
1274        if (details && !details->check_mapping && !details->nonlinear_vma)
1275                details = NULL;
1276
1277        BUG_ON(addr >= end);
1278        mem_cgroup_uncharge_start();
1279        tlb_start_vma(tlb, vma);
1280        pgd = pgd_offset(vma->vm_mm, addr);
1281        do {
1282                next = pgd_addr_end(addr, end);
1283                if (pgd_none_or_clear_bad(pgd))
1284                        continue;
1285                next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1286        } while (pgd++, addr = next, addr != end);
1287        tlb_end_vma(tlb, vma);
1288        mem_cgroup_uncharge_end();
1289
1290        return addr;
1291}
1292
1293/**
1294 * unmap_vmas - unmap a range of memory covered by a list of vma's
1295 * @tlb: address of the caller's struct mmu_gather
1296 * @vma: the starting vma
1297 * @start_addr: virtual address at which to start unmapping
1298 * @end_addr: virtual address at which to end unmapping
1299 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1300 * @details: details of nonlinear truncation or shared cache invalidation
1301 *
1302 * Returns the end address of the unmapping (restart addr if interrupted).
1303 *
1304 * Unmap all pages in the vma list.
1305 *
1306 * Only addresses between `start' and `end' will be unmapped.
1307 *
1308 * The VMA list must be sorted in ascending virtual address order.
1309 *
1310 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1311 * range after unmap_vmas() returns.  So the only responsibility here is to
1312 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1313 * drops the lock and schedules.
1314 */
1315unsigned long unmap_vmas(struct mmu_gather *tlb,
1316                struct vm_area_struct *vma, unsigned long start_addr,
1317                unsigned long end_addr, unsigned long *nr_accounted,
1318                struct zap_details *details)
1319{
1320        unsigned long start = start_addr;
1321        struct mm_struct *mm = vma->vm_mm;
1322
1323        mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1324        for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1325                unsigned long end;
1326
1327                start = max(vma->vm_start, start_addr);
1328                if (start >= vma->vm_end)
1329                        continue;
1330                end = min(vma->vm_end, end_addr);
1331                if (end <= vma->vm_start)
1332                        continue;
1333
1334                if (vma->vm_flags & VM_ACCOUNT)
1335                        *nr_accounted += (end - start) >> PAGE_SHIFT;
1336
1337                if (unlikely(is_pfn_mapping(vma)))
1338                        untrack_pfn_vma(vma, 0, 0);
1339
1340                while (start != end) {
1341                        if (unlikely(is_vm_hugetlb_page(vma))) {
1342                                /*
1343                                 * It is undesirable to test vma->vm_file as it
1344                                 * should be non-null for valid hugetlb area.
1345                                 * However, vm_file will be NULL in the error
1346                                 * cleanup path of do_mmap_pgoff. When
1347                                 * hugetlbfs ->mmap method fails,
1348                                 * do_mmap_pgoff() nullifies vma->vm_file
1349                                 * before calling this function to clean up.
1350                                 * Since no pte has actually been setup, it is
1351                                 * safe to do nothing in this case.
1352                                 */
1353                                if (vma->vm_file)
1354                                        unmap_hugepage_range(vma, start, end, NULL);
1355
1356                                start = end;
1357                        } else
1358                                start = unmap_page_range(tlb, vma, start, end, details);
1359                }
1360        }
1361
1362        mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1363        return start;   /* which is now the end (or restart) address */
1364}
1365
1366/**
1367 * zap_page_range - remove user pages in a given range
1368 * @vma: vm_area_struct holding the applicable pages
1369 * @address: starting address of pages to zap
1370 * @size: number of bytes to zap
1371 * @details: details of nonlinear truncation or shared cache invalidation
1372 */
1373unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1374                unsigned long size, struct zap_details *details)
1375{
1376        struct mm_struct *mm = vma->vm_mm;
1377        struct mmu_gather tlb;
1378        unsigned long end = address + size;
1379        unsigned long nr_accounted = 0;
1380
1381        lru_add_drain();
1382        tlb_gather_mmu(&tlb, mm, 0);
1383        update_hiwater_rss(mm);
1384        end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1385        tlb_finish_mmu(&tlb, address, end);
1386        return end;
1387}
1388
1389/**
1390 * zap_vma_ptes - remove ptes mapping the vma
1391 * @vma: vm_area_struct holding ptes to be zapped
1392 * @address: starting address of pages to zap
1393 * @size: number of bytes to zap
1394 *
1395 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1396 *
1397 * The entire address range must be fully contained within the vma.
1398 *
1399 * Returns 0 if successful.
1400 */
1401int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1402                unsigned long size)
1403{
1404        if (address < vma->vm_start || address + size > vma->vm_end ||
1405                        !(vma->vm_flags & VM_PFNMAP))
1406                return -1;
1407        zap_page_range(vma, address, size, NULL);
1408        return 0;
1409}
1410EXPORT_SYMBOL_GPL(zap_vma_ptes);
1411
1412/**
1413 * follow_page - look up a page descriptor from a user-virtual address
1414 * @vma: vm_area_struct mapping @address
1415 * @address: virtual address to look up
1416 * @flags: flags modifying lookup behaviour
1417 *
1418 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1419 *
1420 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1421 * an error pointer if there is a mapping to something not represented
1422 * by a page descriptor (see also vm_normal_page()).
1423 */
1424struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1425                        unsigned int flags)
1426{
1427        pgd_t *pgd;
1428        pud_t *pud;
1429        pmd_t *pmd;
1430        pte_t *ptep, pte;
1431        spinlock_t *ptl;
1432        struct page *page;
1433        struct mm_struct *mm = vma->vm_mm;
1434
1435        page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1436        if (!IS_ERR(page)) {
1437                BUG_ON(flags & FOLL_GET);
1438                goto out;
1439        }
1440
1441        page = NULL;
1442        pgd = pgd_offset(mm, address);
1443        if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1444                goto no_page_table;
1445
1446        pud = pud_offset(pgd, address);
1447        if (pud_none(*pud))
1448                goto no_page_table;
1449        if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1450                BUG_ON(flags & FOLL_GET);
1451                page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1452                goto out;
1453        }
1454        if (unlikely(pud_bad(*pud)))
1455                goto no_page_table;
1456
1457        pmd = pmd_offset(pud, address);
1458        if (pmd_none(*pmd))
1459                goto no_page_table;
1460        if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1461                BUG_ON(flags & FOLL_GET);
1462                page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1463                goto out;
1464        }
1465        if (pmd_trans_huge(*pmd)) {
1466                if (flags & FOLL_SPLIT) {
1467                        split_huge_page_pmd(mm, pmd);
1468                        goto split_fallthrough;
1469                }
1470                spin_lock(&mm->page_table_lock);
1471                if (likely(pmd_trans_huge(*pmd))) {
1472                        if (unlikely(pmd_trans_splitting(*pmd))) {
1473                                spin_unlock(&mm->page_table_lock);
1474                                wait_split_huge_page(vma->anon_vma, pmd);
1475                        } else {
1476                                page = follow_trans_huge_pmd(mm, address,
1477                                                             pmd, flags);
1478                                spin_unlock(&mm->page_table_lock);
1479                                goto out;
1480                        }
1481                } else
1482                        spin_unlock(&mm->page_table_lock);
1483                /* fall through */
1484        }
1485split_fallthrough:
1486        if (unlikely(pmd_bad(*pmd)))
1487                goto no_page_table;
1488
1489        ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1490
1491        pte = *ptep;
1492        if (!pte_present(pte))
1493                goto no_page;
1494        if ((flags & FOLL_WRITE) && !pte_write(pte))
1495                goto unlock;
1496
1497        page = vm_normal_page(vma, address, pte);
1498        if (unlikely(!page)) {
1499                if ((flags & FOLL_DUMP) ||
1500                    !is_zero_pfn(pte_pfn(pte)))
1501                        goto bad_page;
1502                page = pte_page(pte);
1503        }
1504
1505        if (flags & FOLL_GET)
1506                get_page_foll(page);
1507        if (flags & FOLL_TOUCH) {
1508                if ((flags & FOLL_WRITE) &&
1509                    !pte_dirty(pte) && !PageDirty(page))
1510                        set_page_dirty(page);
1511                /*
1512                 * pte_mkyoung() would be more correct here, but atomic care
1513                 * is needed to avoid losing the dirty bit: it is easier to use
1514                 * mark_page_accessed().
1515                 */
1516                mark_page_accessed(page);
1517        }
1518        if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1519                /*
1520                 * The preliminary mapping check is mainly to avoid the
1521                 * pointless overhead of lock_page on the ZERO_PAGE
1522                 * which might bounce very badly if there is contention.
1523                 *
1524                 * If the page is already locked, we don't need to
1525                 * handle it now - vmscan will handle it later if and
1526                 * when it attempts to reclaim the page.
1527                 */
1528                if (page->mapping && trylock_page(page)) {
1529                        lru_add_drain();  /* push cached pages to LRU */
1530                        /*
1531                         * Because we lock page here and migration is
1532                         * blocked by the pte's page reference, we need
1533                         * only check for file-cache page truncation.
1534                         */
1535                        if (page->mapping)
1536                                mlock_vma_page(page);
1537                        unlock_page(page);
1538                }
1539        }
1540unlock:
1541        pte_unmap_unlock(ptep, ptl);
1542out:
1543        return page;
1544
1545bad_page:
1546        pte_unmap_unlock(ptep, ptl);
1547        return ERR_PTR(-EFAULT);
1548
1549no_page:
1550        pte_unmap_unlock(ptep, ptl);
1551        if (!pte_none(pte))
1552                return page;
1553
1554no_page_table:
1555        /*
1556         * When core dumping an enormous anonymous area that nobody
1557         * has touched so far, we don't want to allocate unnecessary pages or
1558         * page tables.  Return error instead of NULL to skip handle_mm_fault,
1559         * then get_dump_page() will return NULL to leave a hole in the dump.
1560         * But we can only make this optimization where a hole would surely
1561         * be zero-filled if handle_mm_fault() actually did handle it.
1562         */
1563        if ((flags & FOLL_DUMP) &&
1564            (!vma->vm_ops || !vma->vm_ops->fault))
1565                return ERR_PTR(-EFAULT);
1566        return page;
1567}
1568
1569static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1570{
1571        return stack_guard_page_start(vma, addr) ||
1572               stack_guard_page_end(vma, addr+PAGE_SIZE);
1573}
1574
1575/**
1576 * __get_user_pages() - pin user pages in memory
1577 * @tsk:        task_struct of target task
1578 * @mm:         mm_struct of target mm
1579 * @start:      starting user address
1580 * @nr_pages:   number of pages from start to pin
1581 * @gup_flags:  flags modifying pin behaviour
1582 * @pages:      array that receives pointers to the pages pinned.
1583 *              Should be at least nr_pages long. Or NULL, if caller
1584 *              only intends to ensure the pages are faulted in.
1585 * @vmas:       array of pointers to vmas corresponding to each page.
1586 *              Or NULL if the caller does not require them.
1587 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1588 *
1589 * Returns number of pages pinned. This may be fewer than the number
1590 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1591 * were pinned, returns -errno. Each page returned must be released
1592 * with a put_page() call when it is finished with. vmas will only
1593 * remain valid while mmap_sem is held.
1594 *
1595 * Must be called with mmap_sem held for read or write.
1596 *
1597 * __get_user_pages walks a process's page tables and takes a reference to
1598 * each struct page that each user address corresponds to at a given
1599 * instant. That is, it takes the page that would be accessed if a user
1600 * thread accesses the given user virtual address at that instant.
1601 *
1602 * This does not guarantee that the page exists in the user mappings when
1603 * __get_user_pages returns, and there may even be a completely different
1604 * page there in some cases (eg. if mmapped pagecache has been invalidated
1605 * and subsequently re faulted). However it does guarantee that the page
1606 * won't be freed completely. And mostly callers simply care that the page
1607 * contains data that was valid *at some point in time*. Typically, an IO
1608 * or similar operation cannot guarantee anything stronger anyway because
1609 * locks can't be held over the syscall boundary.
1610 *
1611 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1612 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1613 * appropriate) must be called after the page is finished with, and
1614 * before put_page is called.
1615 *
1616 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1617 * or mmap_sem contention, and if waiting is needed to pin all pages,
1618 * *@nonblocking will be set to 0.
1619 *
1620 * In most cases, get_user_pages or get_user_pages_fast should be used
1621 * instead of __get_user_pages. __get_user_pages should be used only if
1622 * you need some special @gup_flags.
1623 */
1624int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1625                     unsigned long start, int nr_pages, unsigned int gup_flags,
1626                     struct page **pages, struct vm_area_struct **vmas,
1627                     int *nonblocking)
1628{
1629        int i;
1630        unsigned long vm_flags;
1631
1632        if (nr_pages <= 0)
1633                return 0;
1634
1635        VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1636
1637        /* 
1638         * Require read or write permissions.
1639         * If FOLL_FORCE is set, we only require the "MAY" flags.
1640         */
1641        vm_flags  = (gup_flags & FOLL_WRITE) ?
1642                        (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1643        vm_flags &= (gup_flags & FOLL_FORCE) ?
1644                        (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1645        i = 0;
1646
1647        do {
1648                struct vm_area_struct *vma;
1649
1650                vma = find_extend_vma(mm, start);
1651                if (!vma && in_gate_area(mm, start)) {
1652                        unsigned long pg = start & PAGE_MASK;
1653                        pgd_t *pgd;
1654                        pud_t *pud;
1655                        pmd_t *pmd;
1656                        pte_t *pte;
1657
1658                        /* user gate pages are read-only */
1659                        if (gup_flags & FOLL_WRITE)
1660                                return i ? : -EFAULT;
1661                        if (pg > TASK_SIZE)
1662                                pgd = pgd_offset_k(pg);
1663                        else
1664                                pgd = pgd_offset_gate(mm, pg);
1665                        BUG_ON(pgd_none(*pgd));
1666                        pud = pud_offset(pgd, pg);
1667                        BUG_ON(pud_none(*pud));
1668                        pmd = pmd_offset(pud, pg);
1669                        if (pmd_none(*pmd))
1670                                return i ? : -EFAULT;
1671                        VM_BUG_ON(pmd_trans_huge(*pmd));
1672                        pte = pte_offset_map(pmd, pg);
1673                        if (pte_none(*pte)) {
1674                                pte_unmap(pte);
1675                                return i ? : -EFAULT;
1676                        }
1677                        vma = get_gate_vma(mm);
1678                        if (pages) {
1679                                struct page *page;
1680
1681                                page = vm_normal_page(vma, start, *pte);
1682                                if (!page) {
1683                                        if (!(gup_flags & FOLL_DUMP) &&
1684                                             is_zero_pfn(pte_pfn(*pte)))
1685                                                page = pte_page(*pte);
1686                                        else {
1687                                                pte_unmap(pte);
1688                                                return i ? : -EFAULT;
1689                                        }
1690                                }
1691                                pages[i] = page;
1692                                get_page(page);
1693                        }
1694                        pte_unmap(pte);
1695                        goto next_page;
1696                }
1697
1698                if (!vma ||
1699                    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1700                    !(vm_flags & vma->vm_flags))
1701                        return i ? : -EFAULT;
1702
1703                if (is_vm_hugetlb_page(vma)) {
1704                        i = follow_hugetlb_page(mm, vma, pages, vmas,
1705                                        &start, &nr_pages, i, gup_flags);
1706                        continue;
1707                }
1708
1709                do {
1710                        struct page *page;
1711                        unsigned int foll_flags = gup_flags;
1712
1713                        /*
1714                         * If we have a pending SIGKILL, don't keep faulting
1715                         * pages and potentially allocating memory.
1716                         */
1717                        if (unlikely(fatal_signal_pending(current)))
1718                                return i ? i : -ERESTARTSYS;
1719
1720                        cond_resched();
1721                        while (!(page = follow_page(vma, start, foll_flags))) {
1722                                int ret;
1723                                unsigned int fault_flags = 0;
1724
1725                                /* For mlock, just skip the stack guard page. */
1726                                if (foll_flags & FOLL_MLOCK) {
1727                                        if (stack_guard_page(vma, start))
1728                                                goto next_page;
1729                                }
1730                                if (foll_flags & FOLL_WRITE)
1731                                        fault_flags |= FAULT_FLAG_WRITE;
1732                                if (nonblocking)
1733                                        fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1734                                if (foll_flags & FOLL_NOWAIT)
1735                                        fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1736
1737                                ret = handle_mm_fault(mm, vma, start,
1738                                                        fault_flags);
1739
1740                                if (ret & VM_FAULT_ERROR) {
1741                                        if (ret & VM_FAULT_OOM)
1742                                                return i ? i : -ENOMEM;
1743                                        if (ret & (VM_FAULT_HWPOISON |
1744                                                   VM_FAULT_HWPOISON_LARGE)) {
1745                                                if (i)
1746                                                        return i;
1747                                                else if (gup_flags & FOLL_HWPOISON)
1748                                                        return -EHWPOISON;
1749                                                else
1750                                                        return -EFAULT;
1751                                        }
1752                                        if (ret & VM_FAULT_SIGBUS)
1753                                                return i ? i : -EFAULT;
1754                                        BUG();
1755                                }
1756
1757                                if (tsk) {
1758                                        if (ret & VM_FAULT_MAJOR)
1759                                                tsk->maj_flt++;
1760                                        else
1761                                                tsk->min_flt++;
1762                                }
1763
1764                                if (ret & VM_FAULT_RETRY) {
1765                                        if (nonblocking)
1766                                                *nonblocking = 0;
1767                                        return i;
1768                                }
1769
1770                                /*
1771                                 * The VM_FAULT_WRITE bit tells us that
1772                                 * do_wp_page has broken COW when necessary,
1773                                 * even if maybe_mkwrite decided not to set
1774                                 * pte_write. We can thus safely do subsequent
1775                                 * page lookups as if they were reads. But only
1776                                 * do so when looping for pte_write is futile:
1777                                 * in some cases userspace may also be wanting
1778                                 * to write to the gotten user page, which a
1779                                 * read fault here might prevent (a readonly
1780                                 * page might get reCOWed by userspace write).
1781                                 */
1782                                if ((ret & VM_FAULT_WRITE) &&
1783                                    !(vma->vm_flags & VM_WRITE))
1784                                        foll_flags &= ~FOLL_WRITE;
1785
1786                                cond_resched();
1787                        }
1788                        if (IS_ERR(page))
1789                                return i ? i : PTR_ERR(page);
1790                        if (pages) {
1791                                pages[i] = page;
1792
1793                                flush_anon_page(vma, page, start);
1794                                flush_dcache_page(page);
1795                        }
1796next_page:
1797                        if (vmas)
1798                                vmas[i] = vma;
1799                        i++;
1800                        start += PAGE_SIZE;
1801                        nr_pages--;
1802                } while (nr_pages && start < vma->vm_end);
1803        } while (nr_pages);
1804        return i;
1805}
1806EXPORT_SYMBOL(__get_user_pages);
1807
1808/*
1809 * fixup_user_fault() - manually resolve a user page fault
1810 * @tsk:        the task_struct to use for page fault accounting, or
1811 *              NULL if faults are not to be recorded.
1812 * @mm:         mm_struct of target mm
1813 * @address:    user address
1814 * @fault_flags:flags to pass down to handle_mm_fault()
1815 *
1816 * This is meant to be called in the specific scenario where for locking reasons
1817 * we try to access user memory in atomic context (within a pagefault_disable()
1818 * section), this returns -EFAULT, and we want to resolve the user fault before
1819 * trying again.
1820 *
1821 * Typically this is meant to be used by the futex code.
1822 *
1823 * The main difference with get_user_pages() is that this function will
1824 * unconditionally call handle_mm_fault() which will in turn perform all the
1825 * necessary SW fixup of the dirty and young bits in the PTE, while
1826 * handle_mm_fault() only guarantees to update these in the struct page.
1827 *
1828 * This is important for some architectures where those bits also gate the
1829 * access permission to the page because they are maintained in software.  On
1830 * such architectures, gup() will not be enough to make a subsequent access
1831 * succeed.
1832 *
1833 * This should be called with the mm_sem held for read.
1834 */
1835int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1836                     unsigned long address, unsigned int fault_flags)
1837{
1838        struct vm_area_struct *vma;
1839        int ret;
1840
1841        vma = find_extend_vma(mm, address);
1842        if (!vma || address < vma->vm_start)
1843                return -EFAULT;
1844
1845        ret = handle_mm_fault(mm, vma, address, fault_flags);
1846        if (ret & VM_FAULT_ERROR) {
1847                if (ret & VM_FAULT_OOM)
1848                        return -ENOMEM;
1849                if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1850                        return -EHWPOISON;
1851                if (ret & VM_FAULT_SIGBUS)
1852                        return -EFAULT;
1853                BUG();
1854        }
1855        if (tsk) {
1856                if (ret & VM_FAULT_MAJOR)
1857                        tsk->maj_flt++;
1858                else
1859                        tsk->min_flt++;
1860        }
1861        return 0;
1862}
1863
1864/*
1865 * get_user_pages() - pin user pages in memory
1866 * @tsk:        the task_struct to use for page fault accounting, or
1867 *              NULL if faults are not to be recorded.
1868 * @mm:         mm_struct of target mm
1869 * @start:      starting user address
1870 * @nr_pages:   number of pages from start to pin
1871 * @write:      whether pages will be written to by the caller
1872 * @force:      whether to force write access even if user mapping is
1873 *              readonly. This will result in the page being COWed even
1874 *              in MAP_SHARED mappings. You do not want this.
1875 * @pages:      array that receives pointers to the pages pinned.
1876 *              Should be at least nr_pages long. Or NULL, if caller
1877 *              only intends to ensure the pages are faulted in.
1878 * @vmas:       array of pointers to vmas corresponding to each page.
1879 *              Or NULL if the caller does not require them.
1880 *
1881 * Returns number of pages pinned. This may be fewer than the number
1882 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1883 * were pinned, returns -errno. Each page returned must be released
1884 * with a put_page() call when it is finished with. vmas will only
1885 * remain valid while mmap_sem is held.
1886 *
1887 * Must be called with mmap_sem held for read or write.
1888 *
1889 * get_user_pages walks a process's page tables and takes a reference to
1890 * each struct page that each user address corresponds to at a given
1891 * instant. That is, it takes the page that would be accessed if a user
1892 * thread accesses the given user virtual address at that instant.
1893 *
1894 * This does not guarantee that the page exists in the user mappings when
1895 * get_user_pages returns, and there may even be a completely different
1896 * page there in some cases (eg. if mmapped pagecache has been invalidated
1897 * and subsequently re faulted). However it does guarantee that the page
1898 * won't be freed completely. And mostly callers simply care that the page
1899 * contains data that was valid *at some point in time*. Typically, an IO
1900 * or similar operation cannot guarantee anything stronger anyway because
1901 * locks can't be held over the syscall boundary.
1902 *
1903 * If write=0, the page must not be written to. If the page is written to,
1904 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1905 * after the page is finished with, and before put_page is called.
1906 *
1907 * get_user_pages is typically used for fewer-copy IO operations, to get a
1908 * handle on the memory by some means other than accesses via the user virtual
1909 * addresses. The pages may be submitted for DMA to devices or accessed via
1910 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1911 * use the correct cache flushing APIs.
1912 *
1913 * See also get_user_pages_fast, for performance critical applications.
1914 */
1915int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1916                unsigned long start, int nr_pages, int write, int force,
1917                struct page **pages, struct vm_area_struct **vmas)
1918{
1919        int flags = FOLL_TOUCH;
1920
1921        if (pages)
1922                flags |= FOLL_GET;
1923        if (write)
1924                flags |= FOLL_WRITE;
1925        if (force)
1926                flags |= FOLL_FORCE;
1927
1928        return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1929                                NULL);
1930}
1931EXPORT_SYMBOL(get_user_pages);
1932
1933/**
1934 * get_dump_page() - pin user page in memory while writing it to core dump
1935 * @addr: user address
1936 *
1937 * Returns struct page pointer of user page pinned for dump,
1938 * to be freed afterwards by page_cache_release() or put_page().
1939 *
1940 * Returns NULL on any kind of failure - a hole must then be inserted into
1941 * the corefile, to preserve alignment with its headers; and also returns
1942 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1943 * allowing a hole to be left in the corefile to save diskspace.
1944 *
1945 * Called without mmap_sem, but after all other threads have been killed.
1946 */
1947#ifdef CONFIG_ELF_CORE
1948struct page *get_dump_page(unsigned long addr)
1949{
1950        struct vm_area_struct *vma;
1951        struct page *page;
1952
1953        if (__get_user_pages(current, current->mm, addr, 1,
1954                             FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1955                             NULL) < 1)
1956                return NULL;
1957        flush_cache_page(vma, addr, page_to_pfn(page));
1958        return page;
1959}
1960#endif /* CONFIG_ELF_CORE */
1961
1962pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1963                        spinlock_t **ptl)
1964{
1965        pgd_t * pgd = pgd_offset(mm, addr);
1966        pud_t * pud = pud_alloc(mm, pgd, addr);
1967        if (pud) {
1968                pmd_t * pmd = pmd_alloc(mm, pud, addr);
1969                if (pmd) {
1970                        VM_BUG_ON(pmd_trans_huge(*pmd));
1971                        return pte_alloc_map_lock(mm, pmd, addr, ptl);
1972                }
1973        }
1974        return NULL;
1975}
1976
1977/*
1978 * This is the old fallback for page remapping.
1979 *
1980 * For historical reasons, it only allows reserved pages. Only
1981 * old drivers should use this, and they needed to mark their
1982 * pages reserved for the old functions anyway.
1983 */
1984static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1985                        struct page *page, pgprot_t prot)
1986{
1987        struct mm_struct *mm = vma->vm_mm;
1988        int retval;
1989        pte_t *pte;
1990        spinlock_t *ptl;
1991
1992        retval = -EINVAL;
1993        if (PageAnon(page))
1994                goto out;
1995        retval = -ENOMEM;
1996        flush_dcache_page(page);
1997        pte = get_locked_pte(mm, addr, &ptl);
1998        if (!pte)
1999                goto out;
2000        retval = -EBUSY;
2001        if (!pte_none(*pte))
2002                goto out_unlock;
2003
2004        /* Ok, finally just insert the thing.. */
2005        get_page(page);
2006        inc_mm_counter_fast(mm, MM_FILEPAGES);
2007        page_add_file_rmap(page);
2008        set_pte_at(mm, addr, pte, mk_pte(page, prot));
2009
2010        retval = 0;
2011        pte_unmap_unlock(pte, ptl);
2012        return retval;
2013out_unlock:
2014        pte_unmap_unlock(pte, ptl);
2015out:
2016        return retval;
2017}
2018
2019/**
2020 * vm_insert_page - insert single page into user vma
2021 * @vma: user vma to map to
2022 * @addr: target user address of this page
2023 * @page: source kernel page
2024 *
2025 * This allows drivers to insert individual pages they've allocated
2026 * into a user vma.
2027 *
2028 * The page has to be a nice clean _individual_ kernel allocation.
2029 * If you allocate a compound page, you need to have marked it as
2030 * such (__GFP_COMP), or manually just split the page up yourself
2031 * (see split_page()).
2032 *
2033 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2034 * took an arbitrary page protection parameter. This doesn't allow
2035 * that. Your vma protection will have to be set up correctly, which
2036 * means that if you want a shared writable mapping, you'd better
2037 * ask for a shared writable mapping!
2038 *
2039 * The page does not need to be reserved.
2040 */
2041int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2042                        struct page *page)
2043{
2044        if (addr < vma->vm_start || addr >= vma->vm_end)
2045                return -EFAULT;
2046        if (!page_count(page))
2047                return -EINVAL;
2048        vma->vm_flags |= VM_INSERTPAGE;
2049        return insert_page(vma, addr, page, vma->vm_page_prot);
2050}
2051EXPORT_SYMBOL(vm_insert_page);
2052
2053static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2054                        unsigned long pfn, pgprot_t prot)
2055{
2056        struct mm_struct *mm = vma->vm_mm;
2057        int retval;
2058        pte_t *pte, entry;
2059        spinlock_t *ptl;
2060
2061        retval = -ENOMEM;
2062        pte = get_locked_pte(mm, addr, &ptl);
2063        if (!pte)
2064                goto out;
2065        retval = -EBUSY;
2066        if (!pte_none(*pte))
2067                goto out_unlock;
2068
2069        /* Ok, finally just insert the thing.. */
2070        entry = pte_mkspecial(pfn_pte(pfn, prot));
2071        set_pte_at(mm, addr, pte, entry);
2072        update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2073
2074        retval = 0;
2075out_unlock:
2076        pte_unmap_unlock(pte, ptl);
2077out:
2078        return retval;
2079}
2080
2081/**
2082 * vm_insert_pfn - insert single pfn into user vma
2083 * @vma: user vma to map to
2084 * @addr: target user address of this page
2085 * @pfn: source kernel pfn
2086 *
2087 * Similar to vm_inert_page, this allows drivers to insert individual pages
2088 * they've allocated into a user vma. Same comments apply.
2089 *
2090 * This function should only be called from a vm_ops->fault handler, and
2091 * in that case the handler should return NULL.
2092 *
2093 * vma cannot be a COW mapping.
2094 *
2095 * As this is called only for pages that do not currently exist, we
2096 * do not need to flush old virtual caches or the TLB.
2097 */
2098int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2099                        unsigned long pfn)
2100{
2101        int ret;
2102        pgprot_t pgprot = vma->vm_page_prot;
2103        /*
2104         * Technically, architectures with pte_special can avoid all these
2105         * restrictions (same for remap_pfn_range).  However we would like
2106         * consistency in testing and feature parity among all, so we should
2107         * try to keep these invariants in place for everybody.
2108         */
2109        BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2110        BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2111                                                (VM_PFNMAP|VM_MIXEDMAP));
2112        BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2113        BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2114
2115        if (addr < vma->vm_start || addr >= vma->vm_end)
2116                return -EFAULT;
2117        if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2118                return -EINVAL;
2119
2120        ret = insert_pfn(vma, addr, pfn, pgprot);
2121
2122        if (ret)
2123                untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2124
2125        return ret;
2126}
2127EXPORT_SYMBOL(vm_insert_pfn);
2128
2129int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2130                        unsigned long pfn)
2131{
2132        BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2133
2134        if (addr < vma->vm_start || addr >= vma->vm_end)
2135                return -EFAULT;
2136
2137        /*
2138         * If we don't have pte special, then we have to use the pfn_valid()
2139         * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2140         * refcount the page if pfn_valid is true (hence insert_page rather
2141         * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
2142         * without pte special, it would there be refcounted as a normal page.
2143         */
2144        if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2145                struct page *page;
2146
2147                page = pfn_to_page(pfn);
2148                return insert_page(vma, addr, page, vma->vm_page_prot);
2149        }
2150        return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2151}
2152EXPORT_SYMBOL(vm_insert_mixed);
2153
2154/*
2155 * maps a range of physical memory into the requested pages. the old
2156 * mappings are removed. any references to nonexistent pages results
2157 * in null mappings (currently treated as "copy-on-access")
2158 */
2159static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2160                        unsigned long addr, unsigned long end,
2161                        unsigned long pfn, pgprot_t prot)
2162{
2163        pte_t *pte;
2164        spinlock_t *ptl;
2165
2166        pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2167        if (!pte)
2168                return -ENOMEM;
2169        arch_enter_lazy_mmu_mode();
2170        do {
2171                BUG_ON(!pte_none(*pte));
2172                set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2173                pfn++;
2174        } while (pte++, addr += PAGE_SIZE, addr != end);
2175        arch_leave_lazy_mmu_mode();
2176        pte_unmap_unlock(pte - 1, ptl);
2177        return 0;
2178}
2179
2180static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2181                        unsigned long addr, unsigned long end,
2182                        unsigned long pfn, pgprot_t prot)
2183{
2184        pmd_t *pmd;
2185        unsigned long next;
2186
2187        pfn -= addr >> PAGE_SHIFT;
2188        pmd = pmd_alloc(mm, pud, addr);
2189        if (!pmd)
2190                return -ENOMEM;
2191        VM_BUG_ON(pmd_trans_huge(*pmd));
2192        do {
2193                next = pmd_addr_end(addr, end);
2194                if (remap_pte_range(mm, pmd, addr, next,
2195                                pfn + (addr >> PAGE_SHIFT), prot))
2196                        return -ENOMEM;
2197        } while (pmd++, addr = next, addr != end);
2198        return 0;
2199}
2200
2201static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2202                        unsigned long addr, unsigned long end,
2203                        unsigned long pfn, pgprot_t prot)
2204{
2205        pud_t *pud;
2206        unsigned long next;
2207
2208        pfn -= addr >> PAGE_SHIFT;
2209        pud = pud_alloc(mm, pgd, addr);
2210        if (!pud)
2211                return -ENOMEM;
2212        do {
2213                next = pud_addr_end(addr, end);
2214                if (remap_pmd_range(mm, pud, addr, next,
2215                                pfn + (addr >> PAGE_SHIFT), prot))
2216                        return -ENOMEM;
2217        } while (pud++, addr = next, addr != end);
2218        return 0;
2219}
2220
2221/**
2222 * remap_pfn_range - remap kernel memory to userspace
2223 * @vma: user vma to map to
2224 * @addr: target user address to start at
2225 * @pfn: physical address of kernel memory
2226 * @size: size of map area
2227 * @prot: page protection flags for this mapping
2228 *
2229 *  Note: this is only safe if the mm semaphore is held when called.
2230 */
2231int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2232                    unsigned long pfn, unsigned long size, pgprot_t prot)
2233{
2234        pgd_t *pgd;
2235        unsigned long next;
2236        unsigned long end = addr + PAGE_ALIGN(size);
2237        struct mm_struct *mm = vma->vm_mm;
2238        int err;
2239
2240        /*
2241         * Physically remapped pages are special. Tell the
2242         * rest of the world about it:
2243         *   VM_IO tells people not to look at these pages
2244         *      (accesses can have side effects).
2245         *   VM_RESERVED is specified all over the place, because
2246         *      in 2.4 it kept swapout's vma scan off this vma; but
2247         *      in 2.6 the LRU scan won't even find its pages, so this
2248         *      flag means no more than count its pages in reserved_vm,
2249         *      and omit it from core dump, even when VM_IO turned off.
2250         *   VM_PFNMAP tells the core MM that the base pages are just
2251         *      raw PFN mappings, and do not have a "struct page" associated
2252         *      with them.
2253         *
2254         * There's a horrible special case to handle copy-on-write
2255         * behaviour that some programs depend on. We mark the "original"
2256         * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2257         */
2258        if (addr == vma->vm_start && end == vma->vm_end) {
2259                vma->vm_pgoff = pfn;
2260                vma->vm_flags |= VM_PFN_AT_MMAP;
2261        } else if (is_cow_mapping(vma->vm_flags))
2262                return -EINVAL;
2263
2264        vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2265
2266        err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2267        if (err) {
2268                /*
2269                 * To indicate that track_pfn related cleanup is not
2270                 * needed from higher level routine calling unmap_vmas
2271                 */
2272                vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2273                vma->vm_flags &= ~VM_PFN_AT_MMAP;
2274                return -EINVAL;
2275        }
2276
2277        BUG_ON(addr >= end);
2278        pfn -= addr >> PAGE_SHIFT;
2279        pgd = pgd_offset(mm, addr);
2280        flush_cache_range(vma, addr, end);
2281        do {
2282                next = pgd_addr_end(addr, end);
2283                err = remap_pud_range(mm, pgd, addr, next,
2284                                pfn + (addr >> PAGE_SHIFT), prot);
2285                if (err)
2286                        break;
2287        } while (pgd++, addr = next, addr != end);
2288
2289        if (err)
2290                untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2291
2292        return err;
2293}
2294EXPORT_SYMBOL(remap_pfn_range);
2295
2296static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2297                                     unsigned long addr, unsigned long end,
2298                                     pte_fn_t fn, void *data)
2299{
2300        pte_t *pte;
2301        int err;
2302        pgtable_t token;
2303        spinlock_t *uninitialized_var(ptl);
2304
2305        pte = (mm == &init_mm) ?
2306                pte_alloc_kernel(pmd, addr) :
2307                pte_alloc_map_lock(mm, pmd, addr, &ptl);
2308        if (!pte)
2309                return -ENOMEM;
2310
2311        BUG_ON(pmd_huge(*pmd));
2312
2313        arch_enter_lazy_mmu_mode();
2314
2315        token = pmd_pgtable(*pmd);
2316
2317        do {
2318                err = fn(pte++, token, addr, data);
2319                if (err)
2320                        break;
2321        } while (addr += PAGE_SIZE, addr != end);
2322
2323        arch_leave_lazy_mmu_mode();
2324
2325        if (mm != &init_mm)
2326                pte_unmap_unlock(pte-1, ptl);
2327        return err;
2328}
2329
2330static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2331                                     unsigned long addr, unsigned long end,
2332                                     pte_fn_t fn, void *data)
2333{
2334        pmd_t *pmd;
2335        unsigned long next;
2336        int err;
2337
2338        BUG_ON(pud_huge(*pud));
2339
2340        pmd = pmd_alloc(mm, pud, addr);
2341        if (!pmd)
2342                return -ENOMEM;
2343        do {
2344                next = pmd_addr_end(addr, end);
2345                err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2346                if (err)
2347                        break;
2348        } while (pmd++, addr = next, addr != end);
2349        return err;
2350}
2351
2352static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2353                                     unsigned long addr, unsigned long end,
2354                                     pte_fn_t fn, void *data)
2355{
2356        pud_t *pud;
2357        unsigned long next;
2358        int err;
2359
2360        pud = pud_alloc(mm, pgd, addr);
2361        if (!pud)
2362                return -ENOMEM;
2363        do {
2364                next = pud_addr_end(addr, end);
2365                err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2366                if (err)
2367                        break;
2368        } while (pud++, addr = next, addr != end);
2369        return err;
2370}
2371
2372/*
2373 * Scan a region of virtual memory, filling in page tables as necessary
2374 * and calling a provided function on each leaf page table.
2375 */
2376int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2377                        unsigned long size, pte_fn_t fn, void *data)
2378{
2379        pgd_t *pgd;
2380        unsigned long next;
2381        unsigned long end = addr + size;
2382        int err;
2383
2384        BUG_ON(addr >= end);
2385        pgd = pgd_offset(mm, addr);
2386        do {
2387                next = pgd_addr_end(addr, end);
2388                err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2389                if (err)
2390                        break;
2391        } while (pgd++, addr = next, addr != end);
2392
2393        return err;
2394}
2395EXPORT_SYMBOL_GPL(apply_to_page_range);
2396
2397/*
2398 * handle_pte_fault chooses page fault handler according to an entry
2399 * which was read non-atomically.  Before making any commitment, on
2400 * those architectures or configurations (e.g. i386 with PAE) which
2401 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2402 * must check under lock before unmapping the pte and proceeding
2403 * (but do_wp_page is only called after already making such a check;
2404 * and do_anonymous_page can safely check later on).
2405 */
2406static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2407                                pte_t *page_table, pte_t orig_pte)
2408{
2409        int same = 1;
2410#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2411        if (sizeof(pte_t) > sizeof(unsigned long)) {
2412                spinlock_t *ptl = pte_lockptr(mm, pmd);
2413                spin_lock(ptl);
2414                same = pte_same(*page_table, orig_pte);
2415                spin_unlock(ptl);
2416        }
2417#endif
2418        pte_unmap(page_table);
2419        return same;
2420}
2421
2422static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2423{
2424        /*
2425         * If the source page was a PFN mapping, we don't have
2426         * a "struct page" for it. We do a best-effort copy by
2427         * just copying from the original user address. If that
2428         * fails, we just zero-fill it. Live with it.
2429         */
2430        if (unlikely(!src)) {
2431                void *kaddr = kmap_atomic(dst, KM_USER0);
2432                void __user *uaddr = (void __user *)(va & PAGE_MASK);
2433
2434                /*
2435                 * This really shouldn't fail, because the page is there
2436                 * in the page tables. But it might just be unreadable,
2437                 * in which case we just give up and fill the result with
2438                 * zeroes.
2439                 */
2440                if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2441                        clear_page(kaddr);
2442                kunmap_atomic(kaddr, KM_USER0);
2443                flush_dcache_page(dst);
2444        } else
2445                copy_user_highpage(dst, src, va, vma);
2446}
2447
2448/*
2449 * This routine handles present pages, when users try to write
2450 * to a shared page. It is done by copying the page to a new address
2451 * and decrementing the shared-page counter for the old page.
2452 *
2453 * Note that this routine assumes that the protection checks have been
2454 * done by the caller (the low-level page fault routine in most cases).
2455 * Thus we can safely just mark it writable once we've done any necessary
2456 * COW.
2457 *
2458 * We also mark the page dirty at this point even though the page will
2459 * change only once the write actually happens. This avoids a few races,
2460 * and potentially makes it more efficient.
2461 *
2462 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2463 * but allow concurrent faults), with pte both mapped and locked.
2464 * We return with mmap_sem still held, but pte unmapped and unlocked.
2465 */
2466static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2467                unsigned long address, pte_t *page_table, pmd_t *pmd,
2468                spinlock_t *ptl, pte_t orig_pte)
2469        __releases(ptl)
2470{
2471        struct page *old_page, *new_page;
2472        pte_t entry;
2473        int ret = 0;
2474        int page_mkwrite = 0;
2475        struct page *dirty_page = NULL;
2476
2477        old_page = vm_normal_page(vma, address, orig_pte);
2478        if (!old_page) {
2479                /*
2480                 * VM_MIXEDMAP !pfn_valid() case
2481                 *
2482                 * We should not cow pages in a shared writeable mapping.
2483                 * Just mark the pages writable as we can't do any dirty
2484                 * accounting on raw pfn maps.
2485                 */
2486                if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2487                                     (VM_WRITE|VM_SHARED))
2488                        goto reuse;
2489                goto gotten;
2490        }
2491
2492        /*
2493         * Take out anonymous pages first, anonymous shared vmas are
2494         * not dirty accountable.
2495         */
2496        if (PageAnon(old_page) && !PageKsm(old_page)) {
2497                if (!trylock_page(old_page)) {
2498                        page_cache_get(old_page);
2499                        pte_unmap_unlock(page_table, ptl);
2500                        lock_page(old_page);
2501                        page_table = pte_offset_map_lock(mm, pmd, address,
2502                                                         &ptl);
2503                        if (!pte_same(*page_table, orig_pte)) {
2504                                unlock_page(old_page);
2505                                goto unlock;
2506                        }
2507                        page_cache_release(old_page);
2508                }
2509                if (reuse_swap_page(old_page)) {
2510                        /*
2511                         * The page is all ours.  Move it to our anon_vma so
2512                         * the rmap code will not search our parent or siblings.
2513                         * Protected against the rmap code by the page lock.
2514                         */
2515                        page_move_anon_rmap(old_page, vma, address);
2516                        unlock_page(old_page);
2517                        goto reuse;
2518                }
2519                unlock_page(old_page);
2520        } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2521                                        (VM_WRITE|VM_SHARED))) {
2522                /*
2523                 * Only catch write-faults on shared writable pages,
2524                 * read-only shared pages can get COWed by
2525                 * get_user_pages(.write=1, .force=1).
2526                 */
2527                if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2528                        struct vm_fault vmf;
2529                        int tmp;
2530
2531                        vmf.virtual_address = (void __user *)(address &
2532                                                                PAGE_MASK);
2533                        vmf.pgoff = old_page->index;
2534                        vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2535                        vmf.page = old_page;
2536
2537                        /*
2538                         * Notify the address space that the page is about to
2539                         * become writable so that it can prohibit this or wait
2540                         * for the page to get into an appropriate state.
2541                         *
2542                         * We do this without the lock held, so that it can
2543                         * sleep if it needs to.
2544                         */
2545                        page_cache_get(old_page);
2546                        pte_unmap_unlock(page_table, ptl);
2547
2548                        tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2549                        if (unlikely(tmp &
2550                                        (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2551                                ret = tmp;
2552                                goto unwritable_page;
2553                        }
2554                        if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2555                                lock_page(old_page);
2556                                if (!old_page->mapping) {
2557                                        ret = 0; /* retry the fault */
2558                                        unlock_page(old_page);
2559                                        goto unwritable_page;
2560                                }
2561                        } else
2562                                VM_BUG_ON(!PageLocked(old_page));
2563
2564                        /*
2565                         * Since we dropped the lock we need to revalidate
2566                         * the PTE as someone else may have changed it.  If
2567                         * they did, we just return, as we can count on the
2568                         * MMU to tell us if they didn't also make it writable.
2569                         */
2570                        page_table = pte_offset_map_lock(mm, pmd, address,
2571                                                         &ptl);
2572                        if (!pte_same(*page_table, orig_pte)) {
2573                                unlock_page(old_page);
2574                                goto unlock;
2575                        }
2576
2577                        page_mkwrite = 1;
2578                }
2579                dirty_page = old_page;
2580                get_page(dirty_page);
2581
2582reuse:
2583                flush_cache_page(vma, address, pte_pfn(orig_pte));
2584                entry = pte_mkyoung(orig_pte);
2585                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2586                if (ptep_set_access_flags(vma, address, page_table, entry,1))
2587                        update_mmu_cache(vma, address, page_table);
2588                pte_unmap_unlock(page_table, ptl);
2589                ret |= VM_FAULT_WRITE;
2590
2591                if (!dirty_page)
2592                        return ret;
2593
2594                /*
2595                 * Yes, Virginia, this is actually required to prevent a race
2596                 * with clear_page_dirty_for_io() from clearing the page dirty
2597                 * bit after it clear all dirty ptes, but before a racing
2598                 * do_wp_page installs a dirty pte.
2599                 *
2600                 * __do_fault is protected similarly.
2601                 */
2602                if (!page_mkwrite) {
2603                        wait_on_page_locked(dirty_page);
2604                        set_page_dirty_balance(dirty_page, page_mkwrite);
2605                }
2606                put_page(dirty_page);
2607                if (page_mkwrite) {
2608                        struct address_space *mapping = dirty_page->mapping;
2609
2610                        set_page_dirty(dirty_page);
2611                        unlock_page(dirty_page);
2612                        page_cache_release(dirty_page);
2613                        if (mapping)    {
2614                                /*
2615                                 * Some device drivers do not set page.mapping
2616                                 * but still dirty their pages
2617                                 */
2618                                balance_dirty_pages_ratelimited(mapping);
2619                        }
2620                }
2621
2622                /* file_update_time outside page_lock */
2623                if (vma->vm_file)
2624                        file_update_time(vma->vm_file);
2625
2626                return ret;
2627        }
2628
2629        /*
2630         * Ok, we need to copy. Oh, well..
2631         */
2632        page_cache_get(old_page);
2633gotten:
2634        pte_unmap_unlock(page_table, ptl);
2635
2636        if (unlikely(anon_vma_prepare(vma)))
2637                goto oom;
2638
2639        if (is_zero_pfn(pte_pfn(orig_pte))) {
2640                new_page = alloc_zeroed_user_highpage_movable(vma, address);
2641                if (!new_page)
2642                        goto oom;
2643        } else {
2644                new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2645                if (!new_page)
2646                        goto oom;
2647                cow_user_page(new_page, old_page, address, vma);
2648        }
2649        __SetPageUptodate(new_page);
2650
2651        if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2652                goto oom_free_new;
2653
2654        /*
2655         * Re-check the pte - we dropped the lock
2656         */
2657        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2658        if (likely(pte_same(*page_table, orig_pte))) {
2659                if (old_page) {
2660                        if (!PageAnon(old_page)) {
2661                                dec_mm_counter_fast(mm, MM_FILEPAGES);
2662                                inc_mm_counter_fast(mm, MM_ANONPAGES);
2663                        }
2664                } else
2665                        inc_mm_counter_fast(mm, MM_ANONPAGES);
2666                flush_cache_page(vma, address, pte_pfn(orig_pte));
2667                entry = mk_pte(new_page, vma->vm_page_prot);
2668                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2669                /*
2670                 * Clear the pte entry and flush it first, before updating the
2671                 * pte with the new entry. This will avoid a race condition
2672                 * seen in the presence of one thread doing SMC and another
2673                 * thread doing COW.
2674                 */
2675                ptep_clear_flush(vma, address, page_table);
2676                page_add_new_anon_rmap(new_page, vma, address);
2677                /*
2678                 * We call the notify macro here because, when using secondary
2679                 * mmu page tables (such as kvm shadow page tables), we want the
2680                 * new page to be mapped directly into the secondary page table.
2681                 */
2682                set_pte_at_notify(mm, address, page_table, entry);
2683                update_mmu_cache(vma, address, page_table);
2684                if (old_page) {
2685                        /*
2686                         * Only after switching the pte to the new page may
2687                         * we remove the mapcount here. Otherwise another
2688                         * process may come and find the rmap count decremented
2689                         * before the pte is switched to the new page, and
2690                         * "reuse" the old page writing into it while our pte
2691                         * here still points into it and can be read by other
2692                         * threads.
2693                         *
2694                         * The critical issue is to order this
2695                         * page_remove_rmap with the ptp_clear_flush above.
2696                         * Those stores are ordered by (if nothing else,)
2697                         * the barrier present in the atomic_add_negative
2698                         * in page_remove_rmap.
2699                         *
2700                         * Then the TLB flush in ptep_clear_flush ensures that
2701                         * no process can access the old page before the
2702                         * decremented mapcount is visible. And the old page
2703                         * cannot be reused until after the decremented
2704                         * mapcount is visible. So transitively, TLBs to
2705                         * old page will be flushed before it can be reused.
2706                         */
2707                        page_remove_rmap(old_page);
2708                }
2709
2710                /* Free the old page.. */
2711                new_page = old_page;
2712                ret |= VM_FAULT_WRITE;
2713        } else
2714                mem_cgroup_uncharge_page(new_page);
2715
2716        if (new_page)
2717                page_cache_release(new_page);
2718unlock:
2719        pte_unmap_unlock(page_table, ptl);
2720        if (old_page) {
2721                /*
2722                 * Don't let another task, with possibly unlocked vma,
2723                 * keep the mlocked page.
2724                 */
2725                if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2726                        lock_page(old_page);    /* LRU manipulation */
2727                        munlock_vma_page(old_page);
2728                        unlock_page(old_page);
2729                }
2730                page_cache_release(old_page);
2731        }
2732        return ret;
2733oom_free_new:
2734        page_cache_release(new_page);
2735oom:
2736        if (old_page) {
2737                if (page_mkwrite) {
2738                        unlock_page(old_page);
2739                        page_cache_release(old_page);
2740                }
2741                page_cache_release(old_page);
2742        }
2743        return VM_FAULT_OOM;
2744
2745unwritable_page:
2746        page_cache_release(old_page);
2747        return ret;
2748}
2749
2750static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2751                unsigned long start_addr, unsigned long end_addr,
2752                struct zap_details *details)
2753{
2754        zap_page_range(vma, start_addr, end_addr - start_addr, details);
2755}
2756
2757static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2758                                            struct zap_details *details)
2759{
2760        struct vm_area_struct *vma;
2761        struct prio_tree_iter iter;
2762        pgoff_t vba, vea, zba, zea;
2763
2764        vma_prio_tree_foreach(vma, &iter, root,
2765                        details->first_index, details->last_index) {
2766
2767                vba = vma->vm_pgoff;
2768                vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2769                /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2770                zba = details->first_index;
2771                if (zba < vba)
2772                        zba = vba;
2773                zea = details->last_index;
2774                if (zea > vea)
2775                        zea = vea;
2776
2777                unmap_mapping_range_vma(vma,
2778                        ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2779                        ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2780                                details);
2781        }
2782}
2783
2784static inline void unmap_mapping_range_list(struct list_head *head,
2785                                            struct zap_details *details)
2786{
2787        struct vm_area_struct *vma;
2788
2789        /*
2790         * In nonlinear VMAs there is no correspondence between virtual address
2791         * offset and file offset.  So we must perform an exhaustive search
2792         * across *all* the pages in each nonlinear VMA, not just the pages
2793         * whose virtual address lies outside the file truncation point.
2794         */
2795        list_for_each_entry(vma, head, shared.vm_set.list) {
2796                details->nonlinear_vma = vma;
2797                unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2798        }
2799}
2800
2801/**
2802 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2803 * @mapping: the address space containing mmaps to be unmapped.
2804 * @holebegin: byte in first page to unmap, relative to the start of
2805 * the underlying file.  This will be rounded down to a PAGE_SIZE
2806 * boundary.  Note that this is different from truncate_pagecache(), which
2807 * must keep the partial page.  In contrast, we must get rid of
2808 * partial pages.
2809 * @holelen: size of prospective hole in bytes.  This will be rounded
2810 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2811 * end of the file.
2812 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2813 * but 0 when invalidating pagecache, don't throw away private data.
2814 */
2815void unmap_mapping_range(struct address_space *mapping,
2816                loff_t const holebegin, loff_t const holelen, int even_cows)
2817{
2818        struct zap_details details;
2819        pgoff_t hba = holebegin >> PAGE_SHIFT;
2820        pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2821
2822        /* Check for overflow. */
2823        if (sizeof(holelen) > sizeof(hlen)) {
2824                long long holeend =
2825                        (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2826                if (holeend & ~(long long)ULONG_MAX)
2827                        hlen = ULONG_MAX - hba + 1;
2828        }
2829
2830        details.check_mapping = even_cows? NULL: mapping;
2831        details.nonlinear_vma = NULL;
2832        details.first_index = hba;
2833        details.last_index = hba + hlen - 1;
2834        if (details.last_index < details.first_index)
2835                details.last_index = ULONG_MAX;
2836
2837
2838        mutex_lock(&mapping->i_mmap_mutex);
2839        if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2840                unmap_mapping_range_tree(&mapping->i_mmap, &details);
2841        if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2842                unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2843        mutex_unlock(&mapping->i_mmap_mutex);
2844}
2845EXPORT_SYMBOL(unmap_mapping_range);
2846
2847/*
2848 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2849 * but allow concurrent faults), and pte mapped but not yet locked.
2850 * We return with mmap_sem still held, but pte unmapped and unlocked.
2851 */
2852static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2853                unsigned long address, pte_t *page_table, pmd_t *pmd,
2854                unsigned int flags, pte_t orig_pte)
2855{
2856        spinlock_t *ptl;
2857        struct page *page, *swapcache = NULL;
2858        swp_entry_t entry;
2859        pte_t pte;
2860        int locked;
2861        struct mem_cgroup *ptr;
2862        int exclusive = 0;
2863        int ret = 0;
2864
2865        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2866                goto out;
2867
2868        entry = pte_to_swp_entry(orig_pte);
2869        if (unlikely(non_swap_entry(entry))) {
2870                if (is_migration_entry(entry)) {
2871                        migration_entry_wait(mm, pmd, address);
2872                } else if (is_hwpoison_entry(entry)) {
2873                        ret = VM_FAULT_HWPOISON;
2874                } else {
2875                        print_bad_pte(vma, address, orig_pte, NULL);
2876                        ret = VM_FAULT_SIGBUS;
2877                }
2878                goto out;
2879        }
2880        delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2881        page = lookup_swap_cache(entry);
2882        if (!page) {
2883                grab_swap_token(mm); /* Contend for token _before_ read-in */
2884                page = swapin_readahead(entry,
2885                                        GFP_HIGHUSER_MOVABLE, vma, address);
2886                if (!page) {
2887                        /*
2888                         * Back out if somebody else faulted in this pte
2889                         * while we released the pte lock.
2890                         */
2891                        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2892                        if (likely(pte_same(*page_table, orig_pte)))
2893                                ret = VM_FAULT_OOM;
2894                        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2895                        goto unlock;
2896                }
2897
2898                /* Had to read the page from swap area: Major fault */
2899                ret = VM_FAULT_MAJOR;
2900                count_vm_event(PGMAJFAULT);
2901                mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2902        } else if (PageHWPoison(page)) {
2903                /*
2904                 * hwpoisoned dirty swapcache pages are kept for killing
2905                 * owner processes (which may be unknown at hwpoison time)
2906                 */
2907                ret = VM_FAULT_HWPOISON;
2908                delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2909                goto out_release;
2910        }
2911
2912        locked = lock_page_or_retry(page, mm, flags);
2913        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2914        if (!locked) {
2915                ret |= VM_FAULT_RETRY;
2916                goto out_release;
2917        }
2918
2919        /*
2920         * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2921         * release the swapcache from under us.  The page pin, and pte_same
2922         * test below, are not enough to exclude that.  Even if it is still
2923         * swapcache, we need to check that the page's swap has not changed.
2924         */
2925        if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2926                goto out_page;
2927
2928        if (ksm_might_need_to_copy(page, vma, address)) {
2929                swapcache = page;
2930                page = ksm_does_need_to_copy(page, vma, address);
2931
2932                if (unlikely(!page)) {
2933                        ret = VM_FAULT_OOM;
2934                        page = swapcache;
2935                        swapcache = NULL;
2936                        goto out_page;
2937                }
2938        }
2939
2940        if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2941                ret = VM_FAULT_OOM;
2942                goto out_page;
2943        }
2944
2945        /*
2946         * Back out if somebody else already faulted in this pte.
2947         */
2948        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2949        if (unlikely(!pte_same(*page_table, orig_pte)))
2950                goto out_nomap;
2951
2952        if (unlikely(!PageUptodate(page))) {
2953                ret = VM_FAULT_SIGBUS;
2954                goto out_nomap;
2955        }
2956
2957        /*
2958         * The page isn't present yet, go ahead with the fault.
2959         *
2960         * Be careful about the sequence of operations here.
2961         * To get its accounting right, reuse_swap_page() must be called
2962         * while the page is counted on swap but not yet in mapcount i.e.
2963         * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2964         * must be called after the swap_free(), or it will never succeed.
2965         * Because delete_from_swap_page() may be called by reuse_swap_page(),
2966         * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2967         * in page->private. In this case, a record in swap_cgroup  is silently
2968         * discarded at swap_free().
2969         */
2970
2971        inc_mm_counter_fast(mm, MM_ANONPAGES);
2972        dec_mm_counter_fast(mm, MM_SWAPENTS);
2973        pte = mk_pte(page, vma->vm_page_prot);
2974        if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2975                pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2976                flags &= ~FAULT_FLAG_WRITE;
2977                ret |= VM_FAULT_WRITE;
2978                exclusive = 1;
2979        }
2980        flush_icache_page(vma, page);
2981        set_pte_at(mm, address, page_table, pte);
2982        do_page_add_anon_rmap(page, vma, address, exclusive);
2983        /* It's better to call commit-charge after rmap is established */
2984        mem_cgroup_commit_charge_swapin(page, ptr);
2985
2986        swap_free(entry);
2987        if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2988                try_to_free_swap(page);
2989        unlock_page(page);
2990        if (swapcache) {
2991                /*
2992                 * Hold the lock to avoid the swap entry to be reused
2993                 * until we take the PT lock for the pte_same() check
2994                 * (to avoid false positives from pte_same). For
2995                 * further safety release the lock after the swap_free
2996                 * so that the swap count won't change under a
2997                 * parallel locked swapcache.
2998                 */
2999                unlock_page(swapcache);
3000                page_cache_release(swapcache);
3001        }
3002
3003        if (flags & FAULT_FLAG_WRITE) {
3004                ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3005                if (ret & VM_FAULT_ERROR)
3006                        ret &= VM_FAULT_ERROR;
3007                goto out;
3008        }
3009
3010        /* No need to invalidate - it was non-present before */
3011        update_mmu_cache(vma, address, page_table);
3012unlock:
3013        pte_unmap_unlock(page_table, ptl);
3014out:
3015        return ret;
3016out_nomap:
3017        mem_cgroup_cancel_charge_swapin(ptr);
3018        pte_unmap_unlock(page_table, ptl);
3019out_page:
3020        unlock_page(page);
3021out_release:
3022        page_cache_release(page);
3023        if (swapcache) {
3024                unlock_page(swapcache);
3025                page_cache_release(swapcache);
3026        }
3027        return ret;
3028}
3029
3030/*
3031 * This is like a special single-page "expand_{down|up}wards()",
3032 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3033 * doesn't hit another vma.
3034 */
3035static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3036{
3037        address &= PAGE_MASK;
3038        if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3039                struct vm_area_struct *prev = vma->vm_prev;
3040
3041                /*
3042                 * Is there a mapping abutting this one below?
3043                 *
3044                 * That's only ok if it's the same stack mapping
3045                 * that has gotten split..
3046                 */
3047                if (prev && prev->vm_end == address)
3048                        return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3049
3050                expand_downwards(vma, address - PAGE_SIZE);
3051        }
3052        if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3053                struct vm_area_struct *next = vma->vm_next;
3054
3055                /* As VM_GROWSDOWN but s/below/above/ */
3056                if (next && next->vm_start == address + PAGE_SIZE)
3057                        return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3058
3059                expand_upwards(vma, address + PAGE_SIZE);
3060        }
3061        return 0;
3062}
3063
3064/*
3065 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3066 * but allow concurrent faults), and pte mapped but not yet locked.
3067 * We return with mmap_sem still held, but pte unmapped and unlocked.
3068 */
3069static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3070                unsigned long address, pte_t *page_table, pmd_t *pmd,
3071                unsigned int flags)
3072{
3073        struct page *page;
3074        spinlock_t *ptl;
3075        pte_t entry;
3076
3077        pte_unmap(page_table);
3078
3079        /* Check if we need to add a guard page to the stack */
3080        if (check_stack_guard_page(vma, address) < 0)
3081                return VM_FAULT_SIGBUS;
3082
3083        /* Use the zero-page for reads */
3084        if (!(flags & FAULT_FLAG_WRITE)) {
3085                entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3086                                                vma->vm_page_prot));
3087                page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3088                if (!pte_none(*page_table))
3089                        goto unlock;
3090                goto setpte;
3091        }
3092
3093        /* Allocate our own private page. */
3094        if (unlikely(anon_vma_prepare(vma)))
3095                goto oom;
3096        page = alloc_zeroed_user_highpage_movable(vma, address);
3097        if (!page)
3098                goto oom;
3099        __SetPageUptodate(page);
3100
3101        if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3102                goto oom_free_page;
3103
3104        entry = mk_pte(page, vma->vm_page_prot);
3105        if (vma->vm_flags & VM_WRITE)
3106                entry = pte_mkwrite(pte_mkdirty(entry));
3107
3108        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3109        if (!pte_none(*page_table))
3110                goto release;
3111
3112        inc_mm_counter_fast(mm, MM_ANONPAGES);
3113        page_add_new_anon_rmap(page, vma, address);
3114setpte:
3115        set_pte_at(mm, address, page_table, entry);
3116
3117        /* No need to invalidate - it was non-present before */
3118        update_mmu_cache(vma, address, page_table);
3119unlock:
3120        pte_unmap_unlock(page_table, ptl);
3121        return 0;
3122release:
3123        mem_cgroup_uncharge_page(page);
3124        page_cache_release(page);
3125        goto unlock;
3126oom_free_page:
3127        page_cache_release(page);
3128oom:
3129        return VM_FAULT_OOM;
3130}
3131
3132/*
3133 * __do_fault() tries to create a new page mapping. It aggressively
3134 * tries to share with existing pages, but makes a separate copy if
3135 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3136 * the next page fault.
3137 *
3138 * As this is called only for pages that do not currently exist, we
3139 * do not need to flush old virtual caches or the TLB.
3140 *
3141 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3142 * but allow concurrent faults), and pte neither mapped nor locked.
3143 * We return with mmap_sem still held, but pte unmapped and unlocked.
3144 */
3145static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3146                unsigned long address, pmd_t *pmd,
3147                pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3148{
3149        pte_t *page_table;
3150        spinlock_t *ptl;
3151        struct page *page;
3152        struct page *cow_page;
3153        pte_t entry;
3154        int anon = 0;
3155        struct page *dirty_page = NULL;
3156        struct vm_fault vmf;
3157        int ret;
3158        int page_mkwrite = 0;
3159
3160        /*
3161         * If we do COW later, allocate page befor taking lock_page()
3162         * on the file cache page. This will reduce lock holding time.
3163         */
3164        if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3165
3166                if (unlikely(anon_vma_prepare(vma)))
3167                        return VM_FAULT_OOM;
3168
3169                cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3170                if (!cow_page)
3171                        return VM_FAULT_OOM;
3172
3173                if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3174                        page_cache_release(cow_page);
3175                        return VM_FAULT_OOM;
3176                }
3177        } else
3178                cow_page = NULL;
3179
3180        vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3181        vmf.pgoff = pgoff;
3182        vmf.flags = flags;
3183        vmf.page = NULL;
3184
3185        ret = vma->vm_ops->fault(vma, &vmf);
3186        if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3187                            VM_FAULT_RETRY)))
3188                goto uncharge_out;
3189
3190        if (unlikely(PageHWPoison(vmf.page))) {
3191                if (ret & VM_FAULT_LOCKED)
3192                        unlock_page(vmf.page);
3193                ret = VM_FAULT_HWPOISON;
3194                goto uncharge_out;
3195        }
3196
3197        /*
3198         * For consistency in subsequent calls, make the faulted page always
3199         * locked.
3200         */
3201        if (unlikely(!(ret & VM_FAULT_LOCKED)))
3202                lock_page(vmf.page);
3203        else
3204                VM_BUG_ON(!PageLocked(vmf.page));
3205
3206        /*
3207         * Should we do an early C-O-W break?
3208         */
3209        page = vmf.page;
3210        if (flags & FAULT_FLAG_WRITE) {
3211                if (!(vma->vm_flags & VM_SHARED)) {
3212                        page = cow_page;
3213                        anon = 1;
3214                        copy_user_highpage(page, vmf.page, address, vma);
3215                        __SetPageUptodate(page);
3216                } else {
3217                        /*
3218                         * If the page will be shareable, see if the backing
3219                         * address space wants to know that the page is about
3220                         * to become writable
3221                         */
3222                        if (vma->vm_ops->page_mkwrite) {
3223                                int tmp;
3224
3225                                unlock_page(page);
3226                                vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3227                                tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3228                                if (unlikely(tmp &
3229                                          (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3230                                        ret = tmp;
3231                                        goto unwritable_page;
3232                                }
3233                                if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3234                                        lock_page(page);
3235                                        if (!page->mapping) {
3236                                                ret = 0; /* retry the fault */
3237                                                unlock_page(page);
3238                                                goto unwritable_page;
3239                                        }
3240                                } else
3241                                        VM_BUG_ON(!PageLocked(page));
3242                                page_mkwrite = 1;
3243                        }
3244                }
3245
3246        }
3247
3248        page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3249
3250        /*
3251         * This silly early PAGE_DIRTY setting removes a race
3252         * due to the bad i386 page protection. But it's valid
3253         * for other architectures too.
3254         *
3255         * Note that if FAULT_FLAG_WRITE is set, we either now have
3256         * an exclusive copy of the page, or this is a shared mapping,
3257         * so we can make it writable and dirty to avoid having to
3258         * handle that later.
3259         */
3260        /* Only go through if we didn't race with anybody else... */
3261        if (likely(pte_same(*page_table, orig_pte))) {
3262                flush_icache_page(vma, page);
3263                entry = mk_pte(page, vma->vm_page_prot);
3264                if (flags & FAULT_FLAG_WRITE)
3265                        entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3266                if (anon) {
3267                        inc_mm_counter_fast(mm, MM_ANONPAGES);
3268                        page_add_new_anon_rmap(page, vma, address);
3269                } else {
3270                        inc_mm_counter_fast(mm, MM_FILEPAGES);
3271                        page_add_file_rmap(page);
3272                        if (flags & FAULT_FLAG_WRITE) {
3273                                dirty_page = page;
3274                                get_page(dirty_page);
3275                        }
3276                }
3277                set_pte_at(mm, address, page_table, entry);
3278
3279                /* no need to invalidate: a not-present page won't be cached */
3280                update_mmu_cache(vma, address, page_table);
3281        } else {
3282                if (cow_page)
3283                        mem_cgroup_uncharge_page(cow_page);
3284                if (anon)
3285                        page_cache_release(page);
3286                else
3287                        anon = 1; /* no anon but release faulted_page */
3288        }
3289
3290        pte_unmap_unlock(page_table, ptl);
3291
3292        if (dirty_page) {
3293                struct address_space *mapping = page->mapping;
3294
3295                if (set_page_dirty(dirty_page))
3296                        page_mkwrite = 1;
3297                unlock_page(dirty_page);
3298                put_page(dirty_page);
3299                if (page_mkwrite && mapping) {
3300                        /*
3301                         * Some device drivers do not set page.mapping but still
3302                         * dirty their pages
3303                         */
3304                        balance_dirty_pages_ratelimited(mapping);
3305                }
3306
3307                /* file_update_time outside page_lock */
3308                if (vma->vm_file)
3309                        file_update_time(vma->vm_file);
3310        } else {
3311                unlock_page(vmf.page);
3312                if (anon)
3313                        page_cache_release(vmf.page);
3314        }
3315
3316        return ret;
3317
3318unwritable_page:
3319        page_cache_release(page);
3320        return ret;
3321uncharge_out:
3322        /* fs's fault handler get error */
3323        if (cow_page) {
3324                mem_cgroup_uncharge_page(cow_page);
3325                page_cache_release(cow_page);
3326        }
3327        return ret;
3328}
3329
3330static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3331                unsigned long address, pte_t *page_table, pmd_t *pmd,
3332                unsigned int flags, pte_t orig_pte)
3333{
3334        pgoff_t pgoff = (((address & PAGE_MASK)
3335                        - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3336
3337        pte_unmap(page_table);
3338        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3339}
3340
3341/*
3342 * Fault of a previously existing named mapping. Repopulate the pte
3343 * from the encoded file_pte if possible. This enables swappable
3344 * nonlinear vmas.
3345 *
3346 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3347 * but allow concurrent faults), and pte mapped but not yet locked.
3348 * We return with mmap_sem still held, but pte unmapped and unlocked.
3349 */
3350static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3351                unsigned long address, pte_t *page_table, pmd_t *pmd,
3352                unsigned int flags, pte_t orig_pte)
3353{
3354        pgoff_t pgoff;
3355
3356        flags |= FAULT_FLAG_NONLINEAR;
3357
3358        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3359                return 0;
3360
3361        if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3362                /*
3363                 * Page table corrupted: show pte and kill process.
3364                 */
3365                print_bad_pte(vma, address, orig_pte, NULL);
3366                return VM_FAULT_SIGBUS;
3367        }
3368
3369        pgoff = pte_to_pgoff(orig_pte);
3370        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3371}
3372
3373/*
3374 * These routines also need to handle stuff like marking pages dirty
3375 * and/or accessed for architectures that don't do it in hardware (most
3376 * RISC architectures).  The early dirtying is also good on the i386.
3377 *
3378 * There is also a hook called "update_mmu_cache()" that architectures
3379 * with external mmu caches can use to update those (ie the Sparc or
3380 * PowerPC hashed page tables that act as extended TLBs).
3381 *
3382 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3383 * but allow concurrent faults), and pte mapped but not yet locked.
3384 * We return with mmap_sem still held, but pte unmapped and unlocked.
3385 */
3386int handle_pte_fault(struct mm_struct *mm,
3387                     struct vm_area_struct *vma, unsigned long address,
3388                     pte_t *pte, pmd_t *pmd, unsigned int flags)
3389{
3390        pte_t entry;
3391        spinlock_t *ptl;
3392
3393        entry = *pte;
3394        if (!pte_present(entry)) {
3395                if (pte_none(entry)) {
3396                        if (vma->vm_ops) {
3397                                if (likely(vma->vm_ops->fault))
3398                                        return do_linear_fault(mm, vma, address,
3399                                                pte, pmd, flags, entry);
3400                        }
3401                        return do_anonymous_page(mm, vma, address,
3402                                                 pte, pmd, flags);
3403                }
3404                if (pte_file(entry))
3405                        return do_nonlinear_fault(mm, vma, address,
3406                                        pte, pmd, flags, entry);
3407                return do_swap_page(mm, vma, address,
3408                                        pte, pmd, flags, entry);
3409        }
3410
3411        ptl = pte_lockptr(mm, pmd);
3412        spin_lock(ptl);
3413        if (unlikely(!pte_same(*pte, entry)))
3414                goto unlock;
3415        if (flags & FAULT_FLAG_WRITE) {
3416                if (!pte_write(entry))
3417                        return do_wp_page(mm, vma, address,
3418                                        pte, pmd, ptl, entry);
3419                entry = pte_mkdirty(entry);
3420        }
3421        entry = pte_mkyoung(entry);
3422        if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3423                update_mmu_cache(vma, address, pte);
3424        } else {
3425                /*
3426                 * This is needed only for protection faults but the arch code
3427                 * is not yet telling us if this is a protection fault or not.
3428                 * This still avoids useless tlb flushes for .text page faults
3429                 * with threads.
3430                 */
3431                if (flags & FAULT_FLAG_WRITE)
3432                        flush_tlb_fix_spurious_fault(vma, address);
3433        }
3434unlock:
3435        pte_unmap_unlock(pte, ptl);
3436        return 0;
3437}
3438
3439/*
3440 * By the time we get here, we already hold the mm semaphore
3441 */
3442int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3443                unsigned long address, unsigned int flags)
3444{
3445        pgd_t *pgd;
3446        pud_t *pud;
3447        pmd_t *pmd;
3448        pte_t *pte;
3449
3450        __set_current_state(TASK_RUNNING);
3451
3452        count_vm_event(PGFAULT);
3453        mem_cgroup_count_vm_event(mm, PGFAULT);
3454
3455        /* do counter updates before entering really critical section. */
3456        check_sync_rss_stat(current);
3457
3458        if (unlikely(is_vm_hugetlb_page(vma)))
3459                return hugetlb_fault(mm, vma, address, flags);
3460
3461        pgd = pgd_offset(mm, address);
3462        pud = pud_alloc(mm, pgd, address);
3463        if (!pud)
3464                return VM_FAULT_OOM;
3465        pmd = pmd_alloc(mm, pud, address);
3466        if (!pmd)
3467                return VM_FAULT_OOM;
3468        if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3469                if (!vma->vm_ops)
3470                        return do_huge_pmd_anonymous_page(mm, vma, address,
3471                                                          pmd, flags);
3472        } else {
3473                pmd_t orig_pmd = *pmd;
3474                barrier();
3475                if (pmd_trans_huge(orig_pmd)) {
3476                        if (flags & FAULT_FLAG_WRITE &&
3477                            !pmd_write(orig_pmd) &&
3478                            !pmd_trans_splitting(orig_pmd))
3479                                return do_huge_pmd_wp_page(mm, vma, address,
3480                                                           pmd, orig_pmd);
3481                        return 0;
3482                }
3483        }
3484
3485        /*
3486         * Use __pte_alloc instead of pte_alloc_map, because we can't
3487         * run pte_offset_map on the pmd, if an huge pmd could
3488         * materialize from under us from a different thread.
3489         */
3490        if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
3491                return VM_FAULT_OOM;
3492        /* if an huge pmd materialized from under us just retry later */
3493        if (unlikely(pmd_trans_huge(*pmd)))
3494                return 0;
3495        /*
3496         * A regular pmd is established and it can't morph into a huge pmd
3497         * from under us anymore at this point because we hold the mmap_sem
3498         * read mode and khugepaged takes it in write mode. So now it's
3499         * safe to run pte_offset_map().
3500         */
3501        pte = pte_offset_map(pmd, address);
3502
3503        return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3504}
3505
3506#ifndef __PAGETABLE_PUD_FOLDED
3507/*
3508 * Allocate page upper directory.
3509 * We've already handled the fast-path in-line.
3510 */
3511int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3512{
3513        pud_t *new = pud_alloc_one(mm, address);
3514        if (!new)
3515                return -ENOMEM;
3516
3517        smp_wmb(); /* See comment in __pte_alloc */
3518
3519        spin_lock(&mm->page_table_lock);
3520        if (pgd_present(*pgd))          /* Another has populated it */
3521                pud_free(mm, new);
3522        else
3523                pgd_populate(mm, pgd, new);
3524        spin_unlock(&mm->page_table_lock);
3525        return 0;
3526}
3527#endif /* __PAGETABLE_PUD_FOLDED */
3528
3529#ifndef __PAGETABLE_PMD_FOLDED
3530/*
3531 * Allocate page middle directory.
3532 * We've already handled the fast-path in-line.
3533 */
3534int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3535{
3536        pmd_t *new = pmd_alloc_one(mm, address);
3537        if (!new)
3538                return -ENOMEM;
3539
3540        smp_wmb(); /* See comment in __pte_alloc */
3541
3542        spin_lock(&mm->page_table_lock);
3543#ifndef __ARCH_HAS_4LEVEL_HACK
3544        if (pud_present(*pud))          /* Another has populated it */
3545                pmd_free(mm, new);
3546        else
3547                pud_populate(mm, pud, new);
3548#else
3549        if (pgd_present(*pud))          /* Another has populated it */
3550                pmd_free(mm, new);
3551        else
3552                pgd_populate(mm, pud, new);
3553#endif /* __ARCH_HAS_4LEVEL_HACK */
3554        spin_unlock(&mm->page_table_lock);
3555        return 0;
3556}
3557#endif /* __PAGETABLE_PMD_FOLDED */
3558
3559int make_pages_present(unsigned long addr, unsigned long end)
3560{
3561        int ret, len, write;
3562        struct vm_area_struct * vma;
3563
3564        vma = find_vma(current->mm, addr);
3565        if (!vma)
3566                return -ENOMEM;
3567        /*
3568         * We want to touch writable mappings with a write fault in order
3569         * to break COW, except for shared mappings because these don't COW
3570         * and we would not want to dirty them for nothing.
3571         */
3572        write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3573        BUG_ON(addr >= end);
3574        BUG_ON(end > vma->vm_end);
3575        len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3576        ret = get_user_pages(current, current->mm, addr,
3577                        len, write, 0, NULL, NULL);
3578        if (ret < 0)
3579                return ret;
3580        return ret == len ? 0 : -EFAULT;
3581}
3582
3583#if !defined(__HAVE_ARCH_GATE_AREA)
3584
3585#if defined(AT_SYSINFO_EHDR)
3586static struct vm_area_struct gate_vma;
3587
3588static int __init gate_vma_init(void)
3589{
3590        gate_vma.vm_mm = NULL;
3591        gate_vma.vm_start = FIXADDR_USER_START;
3592        gate_vma.vm_end = FIXADDR_USER_END;
3593        gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3594        gate_vma.vm_page_prot = __P101;
3595        /*
3596         * Make sure the vDSO gets into every core dump.
3597         * Dumping its contents makes post-mortem fully interpretable later
3598         * without matching up the same kernel and hardware config to see
3599         * what PC values meant.
3600         */
3601        gate_vma.vm_flags |= VM_ALWAYSDUMP;
3602        return 0;
3603}
3604__initcall(gate_vma_init);
3605#endif
3606
3607struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3608{
3609#ifdef AT_SYSINFO_EHDR
3610        return &gate_vma;
3611#else
3612        return NULL;
3613#endif
3614}
3615
3616int in_gate_area_no_mm(unsigned long addr)
3617{
3618#ifdef AT_SYSINFO_EHDR
3619        if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3620                return 1;
3621#endif
3622        return 0;
3623}
3624
3625#endif  /* __HAVE_ARCH_GATE_AREA */
3626
3627static int __follow_pte(struct mm_struct *mm, unsigned long address,
3628                pte_t **ptepp, spinlock_t **ptlp)
3629{
3630        pgd_t *pgd;
3631        pud_t *pud;
3632        pmd_t *pmd;
3633        pte_t *ptep;
3634
3635        pgd = pgd_offset(mm, address);
3636        if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3637                goto out;
3638
3639        pud = pud_offset(pgd, address);
3640        if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3641                goto out;
3642
3643        pmd = pmd_offset(pud, address);
3644        VM_BUG_ON(pmd_trans_huge(*pmd));
3645        if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3646                goto out;
3647
3648        /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3649        if (pmd_huge(*pmd))
3650                goto out;
3651
3652        ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3653        if (!ptep)
3654                goto out;
3655        if (!pte_present(*ptep))
3656                goto unlock;
3657        *ptepp = ptep;
3658        return 0;
3659unlock:
3660        pte_unmap_unlock(ptep, *ptlp);
3661out:
3662        return -EINVAL;
3663}
3664
3665static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3666                             pte_t **ptepp, spinlock_t **ptlp)
3667{
3668        int res;
3669
3670        /* (void) is needed to make gcc happy */
3671        (void) __cond_lock(*ptlp,
3672                           !(res = __follow_pte(mm, address, ptepp, ptlp)));
3673        return res;
3674}
3675
3676/**
3677 * follow_pfn - look up PFN at a user virtual address
3678 * @vma: memory mapping
3679 * @address: user virtual address
3680 * @pfn: location to store found PFN
3681 *
3682 * Only IO mappings and raw PFN mappings are allowed.
3683 *
3684 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3685 */
3686int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3687        unsigned long *pfn)
3688{
3689        int ret = -EINVAL;
3690        spinlock_t *ptl;
3691        pte_t *ptep;
3692
3693        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3694                return ret;
3695
3696        ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3697        if (ret)
3698                return ret;
3699        *pfn = pte_pfn(*ptep);
3700        pte_unmap_unlock(ptep, ptl);
3701        return 0;
3702}
3703EXPORT_SYMBOL(follow_pfn);
3704
3705#ifdef CONFIG_HAVE_IOREMAP_PROT
3706int follow_phys(struct vm_area_struct *vma,
3707                unsigned long address, unsigned int flags,
3708                unsigned long *prot, resource_size_t *phys)
3709{
3710        int ret = -EINVAL;
3711        pte_t *ptep, pte;
3712        spinlock_t *ptl;
3713
3714        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3715                goto out;
3716
3717        if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3718                goto out;
3719        pte = *ptep;
3720
3721        if ((flags & FOLL_WRITE) && !pte_write(pte))
3722                goto unlock;
3723
3724        *prot = pgprot_val(pte_pgprot(pte));
3725        *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3726
3727        ret = 0;
3728unlock:
3729        pte_unmap_unlock(ptep, ptl);
3730out:
3731        return ret;
3732}
3733
3734int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3735                        void *buf, int len, int write)
3736{
3737        resource_size_t phys_addr;
3738        unsigned long prot = 0;
3739        void __iomem *maddr;
3740        int offset = addr & (PAGE_SIZE-1);
3741
3742        if (follow_phys(vma, addr, write, &prot, &phys_addr))
3743                return -EINVAL;
3744
3745        maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3746        if (write)
3747                memcpy_toio(maddr + offset, buf, len);
3748        else
3749                memcpy_fromio(buf, maddr + offset, len);
3750        iounmap(maddr);
3751
3752        return len;
3753}
3754#endif
3755
3756/*
3757 * Access another process' address space as given in mm.  If non-NULL, use the
3758 * given task for page fault accounting.
3759 */
3760static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3761                unsigned long addr, void *buf, int len, int write)
3762{
3763        struct vm_area_struct *vma;
3764        void *old_buf = buf;
3765
3766        down_read(&mm->mmap_sem);
3767        /* ignore errors, just check how much was successfully transferred */
3768        while (len) {
3769                int bytes, ret, offset;
3770                void *maddr;
3771                struct page *page = NULL;
3772
3773                ret = get_user_pages(tsk, mm, addr, 1,
3774                                write, 1, &page, &vma);
3775                if (ret <= 0) {
3776                        /*
3777                         * Check if this is a VM_IO | VM_PFNMAP VMA, which
3778                         * we can access using slightly different code.
3779                         */
3780#ifdef CONFIG_HAVE_IOREMAP_PROT
3781                        vma = find_vma(mm, addr);
3782                        if (!vma || vma->vm_start > addr)
3783                                break;
3784                        if (vma->vm_ops && vma->vm_ops->access)
3785                                ret = vma->vm_ops->access(vma, addr, buf,
3786                                                          len, write);
3787                        if (ret <= 0)
3788#endif
3789                                break;
3790                        bytes = ret;
3791                } else {
3792                        bytes = len;
3793                        offset = addr & (PAGE_SIZE-1);
3794                        if (bytes > PAGE_SIZE-offset)
3795                                bytes = PAGE_SIZE-offset;
3796
3797                        maddr = kmap(page);
3798                        if (write) {
3799                                copy_to_user_page(vma, page, addr,
3800                                                  maddr + offset, buf, bytes);
3801                                set_page_dirty_lock(page);
3802                        } else {
3803                                copy_from_user_page(vma, page, addr,
3804                                                    buf, maddr + offset, bytes);
3805                        }
3806                        kunmap(page);
3807                        page_cache_release(page);
3808                }
3809                len -= bytes;
3810                buf += bytes;
3811                addr += bytes;
3812        }
3813        up_read(&mm->mmap_sem);
3814
3815        return buf - old_buf;
3816}
3817
3818/**
3819 * access_remote_vm - access another process' address space
3820 * @mm:         the mm_struct of the target address space
3821 * @addr:       start address to access
3822 * @buf:        source or destination buffer
3823 * @len:        number of bytes to transfer
3824 * @write:      whether the access is a write
3825 *
3826 * The caller must hold a reference on @mm.
3827 */
3828int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3829                void *buf, int len, int write)
3830{
3831        return __access_remote_vm(NULL, mm, addr, buf, len, write);
3832}
3833
3834/*
3835 * Access another process' address space.
3836 * Source/target buffer must be kernel space,
3837 * Do not walk the page table directly, use get_user_pages
3838 */
3839int access_process_vm(struct task_struct *tsk, unsigned long addr,
3840                void *buf, int len, int write)
3841{
3842        struct mm_struct *mm;
3843        int ret;
3844
3845        mm = get_task_mm(tsk);
3846        if (!mm)
3847                return 0;
3848
3849        ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3850        mmput(mm);
3851
3852        return ret;
3853}
3854
3855/*
3856 * Print the name of a VMA.
3857 */
3858void print_vma_addr(char *prefix, unsigned long ip)
3859{
3860        struct mm_struct *mm = current->mm;
3861        struct vm_area_struct *vma;
3862
3863        /*
3864         * Do not print if we are in atomic
3865         * contexts (in exception stacks, etc.):
3866         */
3867        if (preempt_count())
3868                return;
3869
3870        down_read(&mm->mmap_sem);
3871        vma = find_vma(mm, ip);
3872        if (vma && vma->vm_file) {
3873                struct file *f = vma->vm_file;
3874                char *buf = (char *)__get_free_page(GFP_KERNEL);
3875                if (buf) {
3876                        char *p, *s;
3877
3878                        p = d_path(&f->f_path, buf, PAGE_SIZE);
3879                        if (IS_ERR(p))
3880                                p = "?";
3881                        s = strrchr(p, '/');
3882                        if (s)
3883                                p = s+1;
3884                        printk("%s%s[%lx+%lx]", prefix, p,
3885                                        vma->vm_start,
3886                                        vma->vm_end - vma->vm_start);
3887                        free_page((unsigned long)buf);
3888                }
3889        }
3890        up_read(&current->mm->mmap_sem);
3891}
3892
3893#ifdef CONFIG_PROVE_LOCKING
3894void might_fault(void)
3895{
3896        /*
3897         * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3898         * holding the mmap_sem, this is safe because kernel memory doesn't
3899         * get paged out, therefore we'll never actually fault, and the
3900         * below annotations will generate false positives.
3901         */
3902        if (segment_eq(get_fs(), KERNEL_DS))
3903                return;
3904
3905        might_sleep();
3906        /*
3907         * it would be nicer only to annotate paths which are not under
3908         * pagefault_disable, however that requires a larger audit and
3909         * providing helpers like get_user_atomic.
3910         */
3911        if (!in_atomic() && current->mm)
3912                might_lock_read(&current->mm->mmap_sem);
3913}
3914EXPORT_SYMBOL(might_fault);
3915#endif
3916
3917#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3918static void clear_gigantic_page(struct page *page,
3919                                unsigned long addr,
3920                                unsigned int pages_per_huge_page)
3921{
3922        int i;
3923        struct page *p = page;
3924
3925        might_sleep();
3926        for (i = 0; i < pages_per_huge_page;
3927             i++, p = mem_map_next(p, page, i)) {
3928                cond_resched();
3929                clear_user_highpage(p, addr + i * PAGE_SIZE);
3930        }
3931}
3932void clear_huge_page(struct page *page,
3933                     unsigned long addr, unsigned int pages_per_huge_page)
3934{
3935        int i;
3936
3937        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3938                clear_gigantic_page(page, addr, pages_per_huge_page);
3939                return;
3940        }
3941
3942        might_sleep();
3943        for (i = 0; i < pages_per_huge_page; i++) {
3944                cond_resched();
3945                clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3946        }
3947}
3948
3949static void copy_user_gigantic_page(struct page *dst, struct page *src,
3950                                    unsigned long addr,
3951                                    struct vm_area_struct *vma,
3952                                    unsigned int pages_per_huge_page)
3953{
3954        int i;
3955        struct page *dst_base = dst;
3956        struct page *src_base = src;
3957
3958        for (i = 0; i < pages_per_huge_page; ) {
3959                cond_resched();
3960                copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3961
3962                i++;
3963                dst = mem_map_next(dst, dst_base, i);
3964                src = mem_map_next(src, src_base, i);
3965        }
3966}
3967
3968void copy_user_huge_page(struct page *dst, struct page *src,
3969                         unsigned long addr, struct vm_area_struct *vma,
3970                         unsigned int pages_per_huge_page)
3971{
3972        int i;
3973
3974        if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3975                copy_user_gigantic_page(dst, src, addr, vma,
3976                                        pages_per_huge_page);
3977                return;
3978        }
3979
3980        might_sleep();
3981        for (i = 0; i < pages_per_huge_page; i++) {
3982                cond_resched();
3983                copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3984        }
3985}
3986#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
3987
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