linux/mm/mmap.c
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   1/*
   2 * mm/mmap.c
   3 *
   4 * Written by obz.
   5 *
   6 * Address space accounting code        <alan@redhat.com>
   7 */
   8
   9#include <linux/slab.h>
  10#include <linux/backing-dev.h>
  11#include <linux/mm.h>
  12#include <linux/shm.h>
  13#include <linux/mman.h>
  14#include <linux/pagemap.h>
  15#include <linux/swap.h>
  16#include <linux/syscalls.h>
  17#include <linux/capability.h>
  18#include <linux/init.h>
  19#include <linux/file.h>
  20#include <linux/fs.h>
  21#include <linux/personality.h>
  22#include <linux/security.h>
  23#include <linux/hugetlb.h>
  24#include <linux/profile.h>
  25#include <linux/module.h>
  26#include <linux/mount.h>
  27#include <linux/mempolicy.h>
  28#include <linux/rmap.h>
  29#include <linux/mmu_notifier.h>
  30
  31#include <asm/uaccess.h>
  32#include <asm/cacheflush.h>
  33#include <asm/tlb.h>
  34#include <asm/mmu_context.h>
  35
  36#include "internal.h"
  37
  38#ifndef arch_mmap_check
  39#define arch_mmap_check(addr, len, flags)       (0)
  40#endif
  41
  42#ifndef arch_rebalance_pgtables
  43#define arch_rebalance_pgtables(addr, len)              (addr)
  44#endif
  45
  46static void unmap_region(struct mm_struct *mm,
  47                struct vm_area_struct *vma, struct vm_area_struct *prev,
  48                unsigned long start, unsigned long end);
  49
  50/*
  51 * WARNING: the debugging will use recursive algorithms so never enable this
  52 * unless you know what you are doing.
  53 */
  54#undef DEBUG_MM_RB
  55
  56/* description of effects of mapping type and prot in current implementation.
  57 * this is due to the limited x86 page protection hardware.  The expected
  58 * behavior is in parens:
  59 *
  60 * map_type     prot
  61 *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
  62 * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  63 *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
  64 *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  65 *              
  66 * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  67 *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
  68 *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  69 *
  70 */
  71pgprot_t protection_map[16] = {
  72        __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
  73        __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
  74};
  75
  76pgprot_t vm_get_page_prot(unsigned long vm_flags)
  77{
  78        return __pgprot(pgprot_val(protection_map[vm_flags &
  79                                (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
  80                        pgprot_val(arch_vm_get_page_prot(vm_flags)));
  81}
  82EXPORT_SYMBOL(vm_get_page_prot);
  83
  84int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
  85int sysctl_overcommit_ratio = 50;       /* default is 50% */
  86int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
  87atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
  88
  89/*
  90 * Check that a process has enough memory to allocate a new virtual
  91 * mapping. 0 means there is enough memory for the allocation to
  92 * succeed and -ENOMEM implies there is not.
  93 *
  94 * We currently support three overcommit policies, which are set via the
  95 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
  96 *
  97 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
  98 * Additional code 2002 Jul 20 by Robert Love.
  99 *
 100 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 101 *
 102 * Note this is a helper function intended to be used by LSMs which
 103 * wish to use this logic.
 104 */
 105int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
 106{
 107        unsigned long free, allowed;
 108
 109        vm_acct_memory(pages);
 110
 111        /*
 112         * Sometimes we want to use more memory than we have
 113         */
 114        if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
 115                return 0;
 116
 117        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
 118                unsigned long n;
 119
 120                free = global_page_state(NR_FILE_PAGES);
 121                free += nr_swap_pages;
 122
 123                /*
 124                 * Any slabs which are created with the
 125                 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
 126                 * which are reclaimable, under pressure.  The dentry
 127                 * cache and most inode caches should fall into this
 128                 */
 129                free += global_page_state(NR_SLAB_RECLAIMABLE);
 130
 131                /*
 132                 * Leave the last 3% for root
 133                 */
 134                if (!cap_sys_admin)
 135                        free -= free / 32;
 136
 137                if (free > pages)
 138                        return 0;
 139
 140                /*
 141                 * nr_free_pages() is very expensive on large systems,
 142                 * only call if we're about to fail.
 143                 */
 144                n = nr_free_pages();
 145
 146                /*
 147                 * Leave reserved pages. The pages are not for anonymous pages.
 148                 */
 149                if (n <= totalreserve_pages)
 150                        goto error;
 151                else
 152                        n -= totalreserve_pages;
 153
 154                /*
 155                 * Leave the last 3% for root
 156                 */
 157                if (!cap_sys_admin)
 158                        n -= n / 32;
 159                free += n;
 160
 161                if (free > pages)
 162                        return 0;
 163
 164                goto error;
 165        }
 166
 167        allowed = (totalram_pages - hugetlb_total_pages())
 168                * sysctl_overcommit_ratio / 100;
 169        /*
 170         * Leave the last 3% for root
 171         */
 172        if (!cap_sys_admin)
 173                allowed -= allowed / 32;
 174        allowed += total_swap_pages;
 175
 176        /* Don't let a single process grow too big:
 177           leave 3% of the size of this process for other processes */
 178        if (mm)
 179                allowed -= mm->total_vm / 32;
 180
 181        /*
 182         * cast `allowed' as a signed long because vm_committed_space
 183         * sometimes has a negative value
 184         */
 185        if (atomic_long_read(&vm_committed_space) < (long)allowed)
 186                return 0;
 187error:
 188        vm_unacct_memory(pages);
 189
 190        return -ENOMEM;
 191}
 192
 193/*
 194 * Requires inode->i_mapping->i_mmap_lock
 195 */
 196static void __remove_shared_vm_struct(struct vm_area_struct *vma,
 197                struct file *file, struct address_space *mapping)
 198{
 199        if (vma->vm_flags & VM_DENYWRITE)
 200                atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
 201        if (vma->vm_flags & VM_SHARED)
 202                mapping->i_mmap_writable--;
 203
 204        flush_dcache_mmap_lock(mapping);
 205        if (unlikely(vma->vm_flags & VM_NONLINEAR))
 206                list_del_init(&vma->shared.vm_set.list);
 207        else
 208                vma_prio_tree_remove(vma, &mapping->i_mmap);
 209        flush_dcache_mmap_unlock(mapping);
 210}
 211
 212/*
 213 * Unlink a file-based vm structure from its prio_tree, to hide
 214 * vma from rmap and vmtruncate before freeing its page tables.
 215 */
 216void unlink_file_vma(struct vm_area_struct *vma)
 217{
 218        struct file *file = vma->vm_file;
 219
 220        if (file) {
 221                struct address_space *mapping = file->f_mapping;
 222                spin_lock(&mapping->i_mmap_lock);
 223                __remove_shared_vm_struct(vma, file, mapping);
 224                spin_unlock(&mapping->i_mmap_lock);
 225        }
 226}
 227
 228/*
 229 * Close a vm structure and free it, returning the next.
 230 */
 231static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 232{
 233        struct vm_area_struct *next = vma->vm_next;
 234
 235        might_sleep();
 236        if (vma->vm_ops && vma->vm_ops->close)
 237                vma->vm_ops->close(vma);
 238        if (vma->vm_file) {
 239                fput(vma->vm_file);
 240                if (vma->vm_flags & VM_EXECUTABLE)
 241                        removed_exe_file_vma(vma->vm_mm);
 242        }
 243        mpol_put(vma_policy(vma));
 244        kmem_cache_free(vm_area_cachep, vma);
 245        return next;
 246}
 247
 248asmlinkage unsigned long sys_brk(unsigned long brk)
 249{
 250        unsigned long rlim, retval;
 251        unsigned long newbrk, oldbrk;
 252        struct mm_struct *mm = current->mm;
 253        unsigned long min_brk;
 254
 255        down_write(&mm->mmap_sem);
 256
 257#ifdef CONFIG_COMPAT_BRK
 258        min_brk = mm->end_code;
 259#else
 260        min_brk = mm->start_brk;
 261#endif
 262        if (brk < min_brk)
 263                goto out;
 264
 265        /*
 266         * Check against rlimit here. If this check is done later after the test
 267         * of oldbrk with newbrk then it can escape the test and let the data
 268         * segment grow beyond its set limit the in case where the limit is
 269         * not page aligned -Ram Gupta
 270         */
 271        rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
 272        if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
 273                        (mm->end_data - mm->start_data) > rlim)
 274                goto out;
 275
 276        newbrk = PAGE_ALIGN(brk);
 277        oldbrk = PAGE_ALIGN(mm->brk);
 278        if (oldbrk == newbrk)
 279                goto set_brk;
 280
 281        /* Always allow shrinking brk. */
 282        if (brk <= mm->brk) {
 283                if (!do_munmap(mm, newbrk, oldbrk-newbrk))
 284                        goto set_brk;
 285                goto out;
 286        }
 287
 288        /* Check against existing mmap mappings. */
 289        if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
 290                goto out;
 291
 292        /* Ok, looks good - let it rip. */
 293        if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
 294                goto out;
 295set_brk:
 296        mm->brk = brk;
 297out:
 298        retval = mm->brk;
 299        up_write(&mm->mmap_sem);
 300        return retval;
 301}
 302
 303#ifdef DEBUG_MM_RB
 304static int browse_rb(struct rb_root *root)
 305{
 306        int i = 0, j;
 307        struct rb_node *nd, *pn = NULL;
 308        unsigned long prev = 0, pend = 0;
 309
 310        for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 311                struct vm_area_struct *vma;
 312                vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 313                if (vma->vm_start < prev)
 314                        printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
 315                if (vma->vm_start < pend)
 316                        printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
 317                if (vma->vm_start > vma->vm_end)
 318                        printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
 319                i++;
 320                pn = nd;
 321                prev = vma->vm_start;
 322                pend = vma->vm_end;
 323        }
 324        j = 0;
 325        for (nd = pn; nd; nd = rb_prev(nd)) {
 326                j++;
 327        }
 328        if (i != j)
 329                printk("backwards %d, forwards %d\n", j, i), i = 0;
 330        return i;
 331}
 332
 333void validate_mm(struct mm_struct *mm)
 334{
 335        int bug = 0;
 336        int i = 0;
 337        struct vm_area_struct *tmp = mm->mmap;
 338        while (tmp) {
 339                tmp = tmp->vm_next;
 340                i++;
 341        }
 342        if (i != mm->map_count)
 343                printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
 344        i = browse_rb(&mm->mm_rb);
 345        if (i != mm->map_count)
 346                printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
 347        BUG_ON(bug);
 348}
 349#else
 350#define validate_mm(mm) do { } while (0)
 351#endif
 352
 353static struct vm_area_struct *
 354find_vma_prepare(struct mm_struct *mm, unsigned long addr,
 355                struct vm_area_struct **pprev, struct rb_node ***rb_link,
 356                struct rb_node ** rb_parent)
 357{
 358        struct vm_area_struct * vma;
 359        struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
 360
 361        __rb_link = &mm->mm_rb.rb_node;
 362        rb_prev = __rb_parent = NULL;
 363        vma = NULL;
 364
 365        while (*__rb_link) {
 366                struct vm_area_struct *vma_tmp;
 367
 368                __rb_parent = *__rb_link;
 369                vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
 370
 371                if (vma_tmp->vm_end > addr) {
 372                        vma = vma_tmp;
 373                        if (vma_tmp->vm_start <= addr)
 374                                break;
 375                        __rb_link = &__rb_parent->rb_left;
 376                } else {
 377                        rb_prev = __rb_parent;
 378                        __rb_link = &__rb_parent->rb_right;
 379                }
 380        }
 381
 382        *pprev = NULL;
 383        if (rb_prev)
 384                *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 385        *rb_link = __rb_link;
 386        *rb_parent = __rb_parent;
 387        return vma;
 388}
 389
 390static inline void
 391__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
 392                struct vm_area_struct *prev, struct rb_node *rb_parent)
 393{
 394        if (prev) {
 395                vma->vm_next = prev->vm_next;
 396                prev->vm_next = vma;
 397        } else {
 398                mm->mmap = vma;
 399                if (rb_parent)
 400                        vma->vm_next = rb_entry(rb_parent,
 401                                        struct vm_area_struct, vm_rb);
 402                else
 403                        vma->vm_next = NULL;
 404        }
 405}
 406
 407void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 408                struct rb_node **rb_link, struct rb_node *rb_parent)
 409{
 410        rb_link_node(&vma->vm_rb, rb_parent, rb_link);
 411        rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 412}
 413
 414static void __vma_link_file(struct vm_area_struct *vma)
 415{
 416        struct file * file;
 417
 418        file = vma->vm_file;
 419        if (file) {
 420                struct address_space *mapping = file->f_mapping;
 421
 422                if (vma->vm_flags & VM_DENYWRITE)
 423                        atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
 424                if (vma->vm_flags & VM_SHARED)
 425                        mapping->i_mmap_writable++;
 426
 427                flush_dcache_mmap_lock(mapping);
 428                if (unlikely(vma->vm_flags & VM_NONLINEAR))
 429                        vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
 430                else
 431                        vma_prio_tree_insert(vma, &mapping->i_mmap);
 432                flush_dcache_mmap_unlock(mapping);
 433        }
 434}
 435
 436static void
 437__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 438        struct vm_area_struct *prev, struct rb_node **rb_link,
 439        struct rb_node *rb_parent)
 440{
 441        __vma_link_list(mm, vma, prev, rb_parent);
 442        __vma_link_rb(mm, vma, rb_link, rb_parent);
 443        __anon_vma_link(vma);
 444}
 445
 446static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 447                        struct vm_area_struct *prev, struct rb_node **rb_link,
 448                        struct rb_node *rb_parent)
 449{
 450        struct address_space *mapping = NULL;
 451
 452        if (vma->vm_file)
 453                mapping = vma->vm_file->f_mapping;
 454
 455        if (mapping) {
 456                spin_lock(&mapping->i_mmap_lock);
 457                vma->vm_truncate_count = mapping->truncate_count;
 458        }
 459        anon_vma_lock(vma);
 460
 461        __vma_link(mm, vma, prev, rb_link, rb_parent);
 462        __vma_link_file(vma);
 463
 464        anon_vma_unlock(vma);
 465        if (mapping)
 466                spin_unlock(&mapping->i_mmap_lock);
 467
 468        mm->map_count++;
 469        validate_mm(mm);
 470}
 471
 472/*
 473 * Helper for vma_adjust in the split_vma insert case:
 474 * insert vm structure into list and rbtree and anon_vma,
 475 * but it has already been inserted into prio_tree earlier.
 476 */
 477static void
 478__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
 479{
 480        struct vm_area_struct * __vma, * prev;
 481        struct rb_node ** rb_link, * rb_parent;
 482
 483        __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
 484        BUG_ON(__vma && __vma->vm_start < vma->vm_end);
 485        __vma_link(mm, vma, prev, rb_link, rb_parent);
 486        mm->map_count++;
 487}
 488
 489static inline void
 490__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
 491                struct vm_area_struct *prev)
 492{
 493        prev->vm_next = vma->vm_next;
 494        rb_erase(&vma->vm_rb, &mm->mm_rb);
 495        if (mm->mmap_cache == vma)
 496                mm->mmap_cache = prev;
 497}
 498
 499/*
 500 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 501 * is already present in an i_mmap tree without adjusting the tree.
 502 * The following helper function should be used when such adjustments
 503 * are necessary.  The "insert" vma (if any) is to be inserted
 504 * before we drop the necessary locks.
 505 */
 506void vma_adjust(struct vm_area_struct *vma, unsigned long start,
 507        unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
 508{
 509        struct mm_struct *mm = vma->vm_mm;
 510        struct vm_area_struct *next = vma->vm_next;
 511        struct vm_area_struct *importer = NULL;
 512        struct address_space *mapping = NULL;
 513        struct prio_tree_root *root = NULL;
 514        struct file *file = vma->vm_file;
 515        struct anon_vma *anon_vma = NULL;
 516        long adjust_next = 0;
 517        int remove_next = 0;
 518
 519        if (next && !insert) {
 520                if (end >= next->vm_end) {
 521                        /*
 522                         * vma expands, overlapping all the next, and
 523                         * perhaps the one after too (mprotect case 6).
 524                         */
 525again:                  remove_next = 1 + (end > next->vm_end);
 526                        end = next->vm_end;
 527                        anon_vma = next->anon_vma;
 528                        importer = vma;
 529                } else if (end > next->vm_start) {
 530                        /*
 531                         * vma expands, overlapping part of the next:
 532                         * mprotect case 5 shifting the boundary up.
 533                         */
 534                        adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
 535                        anon_vma = next->anon_vma;
 536                        importer = vma;
 537                } else if (end < vma->vm_end) {
 538                        /*
 539                         * vma shrinks, and !insert tells it's not
 540                         * split_vma inserting another: so it must be
 541                         * mprotect case 4 shifting the boundary down.
 542                         */
 543                        adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
 544                        anon_vma = next->anon_vma;
 545                        importer = next;
 546                }
 547        }
 548
 549        if (file) {
 550                mapping = file->f_mapping;
 551                if (!(vma->vm_flags & VM_NONLINEAR))
 552                        root = &mapping->i_mmap;
 553                spin_lock(&mapping->i_mmap_lock);
 554                if (importer &&
 555                    vma->vm_truncate_count != next->vm_truncate_count) {
 556                        /*
 557                         * unmap_mapping_range might be in progress:
 558                         * ensure that the expanding vma is rescanned.
 559                         */
 560                        importer->vm_truncate_count = 0;
 561                }
 562                if (insert) {
 563                        insert->vm_truncate_count = vma->vm_truncate_count;
 564                        /*
 565                         * Put into prio_tree now, so instantiated pages
 566                         * are visible to arm/parisc __flush_dcache_page
 567                         * throughout; but we cannot insert into address
 568                         * space until vma start or end is updated.
 569                         */
 570                        __vma_link_file(insert);
 571                }
 572        }
 573
 574        /*
 575         * When changing only vma->vm_end, we don't really need
 576         * anon_vma lock: but is that case worth optimizing out?
 577         */
 578        if (vma->anon_vma)
 579                anon_vma = vma->anon_vma;
 580        if (anon_vma) {
 581                spin_lock(&anon_vma->lock);
 582                /*
 583                 * Easily overlooked: when mprotect shifts the boundary,
 584                 * make sure the expanding vma has anon_vma set if the
 585                 * shrinking vma had, to cover any anon pages imported.
 586                 */
 587                if (importer && !importer->anon_vma) {
 588                        importer->anon_vma = anon_vma;
 589                        __anon_vma_link(importer);
 590                }
 591        }
 592
 593        if (root) {
 594                flush_dcache_mmap_lock(mapping);
 595                vma_prio_tree_remove(vma, root);
 596                if (adjust_next)
 597                        vma_prio_tree_remove(next, root);
 598        }
 599
 600        vma->vm_start = start;
 601        vma->vm_end = end;
 602        vma->vm_pgoff = pgoff;
 603        if (adjust_next) {
 604                next->vm_start += adjust_next << PAGE_SHIFT;
 605                next->vm_pgoff += adjust_next;
 606        }
 607
 608        if (root) {
 609                if (adjust_next)
 610                        vma_prio_tree_insert(next, root);
 611                vma_prio_tree_insert(vma, root);
 612                flush_dcache_mmap_unlock(mapping);
 613        }
 614
 615        if (remove_next) {
 616                /*
 617                 * vma_merge has merged next into vma, and needs
 618                 * us to remove next before dropping the locks.
 619                 */
 620                __vma_unlink(mm, next, vma);
 621                if (file)
 622                        __remove_shared_vm_struct(next, file, mapping);
 623                if (next->anon_vma)
 624                        __anon_vma_merge(vma, next);
 625        } else if (insert) {
 626                /*
 627                 * split_vma has split insert from vma, and needs
 628                 * us to insert it before dropping the locks
 629                 * (it may either follow vma or precede it).
 630                 */
 631                __insert_vm_struct(mm, insert);
 632        }
 633
 634        if (anon_vma)
 635                spin_unlock(&anon_vma->lock);
 636        if (mapping)
 637                spin_unlock(&mapping->i_mmap_lock);
 638
 639        if (remove_next) {
 640                if (file) {
 641                        fput(file);
 642                        if (next->vm_flags & VM_EXECUTABLE)
 643                                removed_exe_file_vma(mm);
 644                }
 645                mm->map_count--;
 646                mpol_put(vma_policy(next));
 647                kmem_cache_free(vm_area_cachep, next);
 648                /*
 649                 * In mprotect's case 6 (see comments on vma_merge),
 650                 * we must remove another next too. It would clutter
 651                 * up the code too much to do both in one go.
 652                 */
 653                if (remove_next == 2) {
 654                        next = vma->vm_next;
 655                        goto again;
 656                }
 657        }
 658
 659        validate_mm(mm);
 660}
 661
 662/*
 663 * If the vma has a ->close operation then the driver probably needs to release
 664 * per-vma resources, so we don't attempt to merge those.
 665 */
 666static inline int is_mergeable_vma(struct vm_area_struct *vma,
 667                        struct file *file, unsigned long vm_flags)
 668{
 669        if (vma->vm_flags != vm_flags)
 670                return 0;
 671        if (vma->vm_file != file)
 672                return 0;
 673        if (vma->vm_ops && vma->vm_ops->close)
 674                return 0;
 675        return 1;
 676}
 677
 678static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
 679                                        struct anon_vma *anon_vma2)
 680{
 681        return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
 682}
 683
 684/*
 685 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 686 * in front of (at a lower virtual address and file offset than) the vma.
 687 *
 688 * We cannot merge two vmas if they have differently assigned (non-NULL)
 689 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 690 *
 691 * We don't check here for the merged mmap wrapping around the end of pagecache
 692 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 693 * wrap, nor mmaps which cover the final page at index -1UL.
 694 */
 695static int
 696can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
 697        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 698{
 699        if (is_mergeable_vma(vma, file, vm_flags) &&
 700            is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
 701                if (vma->vm_pgoff == vm_pgoff)
 702                        return 1;
 703        }
 704        return 0;
 705}
 706
 707/*
 708 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 709 * beyond (at a higher virtual address and file offset than) the vma.
 710 *
 711 * We cannot merge two vmas if they have differently assigned (non-NULL)
 712 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 713 */
 714static int
 715can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 716        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 717{
 718        if (is_mergeable_vma(vma, file, vm_flags) &&
 719            is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
 720                pgoff_t vm_pglen;
 721                vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 722                if (vma->vm_pgoff + vm_pglen == vm_pgoff)
 723                        return 1;
 724        }
 725        return 0;
 726}
 727
 728/*
 729 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
 730 * whether that can be merged with its predecessor or its successor.
 731 * Or both (it neatly fills a hole).
 732 *
 733 * In most cases - when called for mmap, brk or mremap - [addr,end) is
 734 * certain not to be mapped by the time vma_merge is called; but when
 735 * called for mprotect, it is certain to be already mapped (either at
 736 * an offset within prev, or at the start of next), and the flags of
 737 * this area are about to be changed to vm_flags - and the no-change
 738 * case has already been eliminated.
 739 *
 740 * The following mprotect cases have to be considered, where AAAA is
 741 * the area passed down from mprotect_fixup, never extending beyond one
 742 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
 743 *
 744 *     AAAA             AAAA                AAAA          AAAA
 745 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
 746 *    cannot merge    might become    might become    might become
 747 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
 748 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
 749 *    mremap move:                                    PPPPNNNNNNNN 8
 750 *        AAAA
 751 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
 752 *    might become    case 1 below    case 2 below    case 3 below
 753 *
 754 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
 755 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
 756 */
 757struct vm_area_struct *vma_merge(struct mm_struct *mm,
 758                        struct vm_area_struct *prev, unsigned long addr,
 759                        unsigned long end, unsigned long vm_flags,
 760                        struct anon_vma *anon_vma, struct file *file,
 761                        pgoff_t pgoff, struct mempolicy *policy)
 762{
 763        pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
 764        struct vm_area_struct *area, *next;
 765
 766        /*
 767         * We later require that vma->vm_flags == vm_flags,
 768         * so this tests vma->vm_flags & VM_SPECIAL, too.
 769         */
 770        if (vm_flags & VM_SPECIAL)
 771                return NULL;
 772
 773        if (prev)
 774                next = prev->vm_next;
 775        else
 776                next = mm->mmap;
 777        area = next;
 778        if (next && next->vm_end == end)                /* cases 6, 7, 8 */
 779                next = next->vm_next;
 780
 781        /*
 782         * Can it merge with the predecessor?
 783         */
 784        if (prev && prev->vm_end == addr &&
 785                        mpol_equal(vma_policy(prev), policy) &&
 786                        can_vma_merge_after(prev, vm_flags,
 787                                                anon_vma, file, pgoff)) {
 788                /*
 789                 * OK, it can.  Can we now merge in the successor as well?
 790                 */
 791                if (next && end == next->vm_start &&
 792                                mpol_equal(policy, vma_policy(next)) &&
 793                                can_vma_merge_before(next, vm_flags,
 794                                        anon_vma, file, pgoff+pglen) &&
 795                                is_mergeable_anon_vma(prev->anon_vma,
 796                                                      next->anon_vma)) {
 797                                                        /* cases 1, 6 */
 798                        vma_adjust(prev, prev->vm_start,
 799                                next->vm_end, prev->vm_pgoff, NULL);
 800                } else                                  /* cases 2, 5, 7 */
 801                        vma_adjust(prev, prev->vm_start,
 802                                end, prev->vm_pgoff, NULL);
 803                return prev;
 804        }
 805
 806        /*
 807         * Can this new request be merged in front of next?
 808         */
 809        if (next && end == next->vm_start &&
 810                        mpol_equal(policy, vma_policy(next)) &&
 811                        can_vma_merge_before(next, vm_flags,
 812                                        anon_vma, file, pgoff+pglen)) {
 813                if (prev && addr < prev->vm_end)        /* case 4 */
 814                        vma_adjust(prev, prev->vm_start,
 815                                addr, prev->vm_pgoff, NULL);
 816                else                                    /* cases 3, 8 */
 817                        vma_adjust(area, addr, next->vm_end,
 818                                next->vm_pgoff - pglen, NULL);
 819                return area;
 820        }
 821
 822        return NULL;
 823}
 824
 825/*
 826 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
 827 * neighbouring vmas for a suitable anon_vma, before it goes off
 828 * to allocate a new anon_vma.  It checks because a repetitive
 829 * sequence of mprotects and faults may otherwise lead to distinct
 830 * anon_vmas being allocated, preventing vma merge in subsequent
 831 * mprotect.
 832 */
 833struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
 834{
 835        struct vm_area_struct *near;
 836        unsigned long vm_flags;
 837
 838        near = vma->vm_next;
 839        if (!near)
 840                goto try_prev;
 841
 842        /*
 843         * Since only mprotect tries to remerge vmas, match flags
 844         * which might be mprotected into each other later on.
 845         * Neither mlock nor madvise tries to remerge at present,
 846         * so leave their flags as obstructing a merge.
 847         */
 848        vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
 849        vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
 850
 851        if (near->anon_vma && vma->vm_end == near->vm_start &&
 852                        mpol_equal(vma_policy(vma), vma_policy(near)) &&
 853                        can_vma_merge_before(near, vm_flags,
 854                                NULL, vma->vm_file, vma->vm_pgoff +
 855                                ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
 856                return near->anon_vma;
 857try_prev:
 858        /*
 859         * It is potentially slow to have to call find_vma_prev here.
 860         * But it's only on the first write fault on the vma, not
 861         * every time, and we could devise a way to avoid it later
 862         * (e.g. stash info in next's anon_vma_node when assigning
 863         * an anon_vma, or when trying vma_merge).  Another time.
 864         */
 865        BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
 866        if (!near)
 867                goto none;
 868
 869        vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
 870        vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
 871
 872        if (near->anon_vma && near->vm_end == vma->vm_start &&
 873                        mpol_equal(vma_policy(near), vma_policy(vma)) &&
 874                        can_vma_merge_after(near, vm_flags,
 875                                NULL, vma->vm_file, vma->vm_pgoff))
 876                return near->anon_vma;
 877none:
 878        /*
 879         * There's no absolute need to look only at touching neighbours:
 880         * we could search further afield for "compatible" anon_vmas.
 881         * But it would probably just be a waste of time searching,
 882         * or lead to too many vmas hanging off the same anon_vma.
 883         * We're trying to allow mprotect remerging later on,
 884         * not trying to minimize memory used for anon_vmas.
 885         */
 886        return NULL;
 887}
 888
 889#ifdef CONFIG_PROC_FS
 890void vm_stat_account(struct mm_struct *mm, unsigned long flags,
 891                                                struct file *file, long pages)
 892{
 893        const unsigned long stack_flags
 894                = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
 895
 896        if (file) {
 897                mm->shared_vm += pages;
 898                if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
 899                        mm->exec_vm += pages;
 900        } else if (flags & stack_flags)
 901                mm->stack_vm += pages;
 902        if (flags & (VM_RESERVED|VM_IO))
 903                mm->reserved_vm += pages;
 904}
 905#endif /* CONFIG_PROC_FS */
 906
 907/*
 908 * The caller must hold down_write(current->mm->mmap_sem).
 909 */
 910
 911unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 912                        unsigned long len, unsigned long prot,
 913                        unsigned long flags, unsigned long pgoff)
 914{
 915        struct mm_struct * mm = current->mm;
 916        struct inode *inode;
 917        unsigned int vm_flags;
 918        int error;
 919        int accountable = 1;
 920        unsigned long reqprot = prot;
 921
 922        /*
 923         * Does the application expect PROT_READ to imply PROT_EXEC?
 924         *
 925         * (the exception is when the underlying filesystem is noexec
 926         *  mounted, in which case we dont add PROT_EXEC.)
 927         */
 928        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
 929                if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
 930                        prot |= PROT_EXEC;
 931
 932        if (!len)
 933                return -EINVAL;
 934
 935        if (!(flags & MAP_FIXED))
 936                addr = round_hint_to_min(addr);
 937
 938        error = arch_mmap_check(addr, len, flags);
 939        if (error)
 940                return error;
 941
 942        /* Careful about overflows.. */
 943        len = PAGE_ALIGN(len);
 944        if (!len || len > TASK_SIZE)
 945                return -ENOMEM;
 946
 947        /* offset overflow? */
 948        if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 949               return -EOVERFLOW;
 950
 951        /* Too many mappings? */
 952        if (mm->map_count > sysctl_max_map_count)
 953                return -ENOMEM;
 954
 955        /* Obtain the address to map to. we verify (or select) it and ensure
 956         * that it represents a valid section of the address space.
 957         */
 958        addr = get_unmapped_area(file, addr, len, pgoff, flags);
 959        if (addr & ~PAGE_MASK)
 960                return addr;
 961
 962        /* Do simple checking here so the lower-level routines won't have
 963         * to. we assume access permissions have been handled by the open
 964         * of the memory object, so we don't do any here.
 965         */
 966        vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
 967                        mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 968
 969        if (flags & MAP_LOCKED) {
 970                if (!can_do_mlock())
 971                        return -EPERM;
 972                vm_flags |= VM_LOCKED;
 973        }
 974
 975        /* mlock MCL_FUTURE? */
 976        if (vm_flags & VM_LOCKED) {
 977                unsigned long locked, lock_limit;
 978                locked = len >> PAGE_SHIFT;
 979                locked += mm->locked_vm;
 980                lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
 981                lock_limit >>= PAGE_SHIFT;
 982                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
 983                        return -EAGAIN;
 984        }
 985
 986        inode = file ? file->f_path.dentry->d_inode : NULL;
 987
 988        if (file) {
 989                switch (flags & MAP_TYPE) {
 990                case MAP_SHARED:
 991                        if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
 992                                return -EACCES;
 993
 994                        /*
 995                         * Make sure we don't allow writing to an append-only
 996                         * file..
 997                         */
 998                        if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
 999                                return -EACCES;
1000
1001                        /*
1002                         * Make sure there are no mandatory locks on the file.
1003                         */
1004                        if (locks_verify_locked(inode))
1005                                return -EAGAIN;
1006
1007                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1008                        if (!(file->f_mode & FMODE_WRITE))
1009                                vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1010
1011                        /* fall through */
1012                case MAP_PRIVATE:
1013                        if (!(file->f_mode & FMODE_READ))
1014                                return -EACCES;
1015                        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1016                                if (vm_flags & VM_EXEC)
1017                                        return -EPERM;
1018                                vm_flags &= ~VM_MAYEXEC;
1019                        }
1020                        if (is_file_hugepages(file))
1021                                accountable = 0;
1022
1023                        if (!file->f_op || !file->f_op->mmap)
1024                                return -ENODEV;
1025                        break;
1026
1027                default:
1028                        return -EINVAL;
1029                }
1030        } else {
1031                switch (flags & MAP_TYPE) {
1032                case MAP_SHARED:
1033                        /*
1034                         * Ignore pgoff.
1035                         */
1036                        pgoff = 0;
1037                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1038                        break;
1039                case MAP_PRIVATE:
1040                        /*
1041                         * Set pgoff according to addr for anon_vma.
1042                         */
1043                        pgoff = addr >> PAGE_SHIFT;
1044                        break;
1045                default:
1046                        return -EINVAL;
1047                }
1048        }
1049
1050        error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1051        if (error)
1052                return error;
1053
1054        return mmap_region(file, addr, len, flags, vm_flags, pgoff,
1055                           accountable);
1056}
1057EXPORT_SYMBOL(do_mmap_pgoff);
1058
1059/*
1060 * Some shared mappigns will want the pages marked read-only
1061 * to track write events. If so, we'll downgrade vm_page_prot
1062 * to the private version (using protection_map[] without the
1063 * VM_SHARED bit).
1064 */
1065int vma_wants_writenotify(struct vm_area_struct *vma)
1066{
1067        unsigned int vm_flags = vma->vm_flags;
1068
1069        /* If it was private or non-writable, the write bit is already clear */
1070        if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1071                return 0;
1072
1073        /* The backer wishes to know when pages are first written to? */
1074        if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1075                return 1;
1076
1077        /* The open routine did something to the protections already? */
1078        if (pgprot_val(vma->vm_page_prot) !=
1079            pgprot_val(vm_get_page_prot(vm_flags)))
1080                return 0;
1081
1082        /* Specialty mapping? */
1083        if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1084                return 0;
1085
1086        /* Can the mapping track the dirty pages? */
1087        return vma->vm_file && vma->vm_file->f_mapping &&
1088                mapping_cap_account_dirty(vma->vm_file->f_mapping);
1089}
1090
1091unsigned long mmap_region(struct file *file, unsigned long addr,
1092                          unsigned long len, unsigned long flags,
1093                          unsigned int vm_flags, unsigned long pgoff,
1094                          int accountable)
1095{
1096        struct mm_struct *mm = current->mm;
1097        struct vm_area_struct *vma, *prev;
1098        int correct_wcount = 0;
1099        int error;
1100        struct rb_node **rb_link, *rb_parent;
1101        unsigned long charged = 0;
1102        struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
1103
1104        /* Clear old maps */
1105        error = -ENOMEM;
1106munmap_back:
1107        vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1108        if (vma && vma->vm_start < addr + len) {
1109                if (do_munmap(mm, addr, len))
1110                        return -ENOMEM;
1111                goto munmap_back;
1112        }
1113
1114        /* Check against address space limit. */
1115        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1116                return -ENOMEM;
1117
1118        if (flags & MAP_NORESERVE)
1119                vm_flags |= VM_NORESERVE;
1120
1121        if (accountable && (!(flags & MAP_NORESERVE) ||
1122                            sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1123                if (vm_flags & VM_SHARED) {
1124                        /* Check memory availability in shmem_file_setup? */
1125                        vm_flags |= VM_ACCOUNT;
1126                } else if (vm_flags & VM_WRITE) {
1127                        /*
1128                         * Private writable mapping: check memory availability
1129                         */
1130                        charged = len >> PAGE_SHIFT;
1131                        if (security_vm_enough_memory(charged))
1132                                return -ENOMEM;
1133                        vm_flags |= VM_ACCOUNT;
1134                }
1135        }
1136
1137        /*
1138         * Can we just expand an old private anonymous mapping?
1139         * The VM_SHARED test is necessary because shmem_zero_setup
1140         * will create the file object for a shared anonymous map below.
1141         */
1142        if (!file && !(vm_flags & VM_SHARED)) {
1143                vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1144                                        NULL, NULL, pgoff, NULL);
1145                if (vma)
1146                        goto out;
1147        }
1148
1149        /*
1150         * Determine the object being mapped and call the appropriate
1151         * specific mapper. the address has already been validated, but
1152         * not unmapped, but the maps are removed from the list.
1153         */
1154        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1155        if (!vma) {
1156                error = -ENOMEM;
1157                goto unacct_error;
1158        }
1159
1160        vma->vm_mm = mm;
1161        vma->vm_start = addr;
1162        vma->vm_end = addr + len;
1163        vma->vm_flags = vm_flags;
1164        vma->vm_page_prot = vm_get_page_prot(vm_flags);
1165        vma->vm_pgoff = pgoff;
1166
1167        if (file) {
1168                error = -EINVAL;
1169                if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1170                        goto free_vma;
1171                if (vm_flags & VM_DENYWRITE) {
1172                        error = deny_write_access(file);
1173                        if (error)
1174                                goto free_vma;
1175                        correct_wcount = 1;
1176                }
1177                vma->vm_file = file;
1178                get_file(file);
1179                error = file->f_op->mmap(file, vma);
1180                if (error)
1181                        goto unmap_and_free_vma;
1182                if (vm_flags & VM_EXECUTABLE)
1183                        added_exe_file_vma(mm);
1184        } else if (vm_flags & VM_SHARED) {
1185                error = shmem_zero_setup(vma);
1186                if (error)
1187                        goto free_vma;
1188        }
1189
1190        /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1191         * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1192         * that memory reservation must be checked; but that reservation
1193         * belongs to shared memory object, not to vma: so now clear it.
1194         */
1195        if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1196                vma->vm_flags &= ~VM_ACCOUNT;
1197
1198        /* Can addr have changed??
1199         *
1200         * Answer: Yes, several device drivers can do it in their
1201         *         f_op->mmap method. -DaveM
1202         */
1203        addr = vma->vm_start;
1204        pgoff = vma->vm_pgoff;
1205        vm_flags = vma->vm_flags;
1206
1207        if (vma_wants_writenotify(vma))
1208                vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1209
1210        if (file && vma_merge(mm, prev, addr, vma->vm_end,
1211                        vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1212                mpol_put(vma_policy(vma));
1213                kmem_cache_free(vm_area_cachep, vma);
1214                fput(file);
1215                if (vm_flags & VM_EXECUTABLE)
1216                        removed_exe_file_vma(mm);
1217        } else {
1218                vma_link(mm, vma, prev, rb_link, rb_parent);
1219                file = vma->vm_file;
1220        }
1221
1222        /* Once vma denies write, undo our temporary denial count */
1223        if (correct_wcount)
1224                atomic_inc(&inode->i_writecount);
1225out:
1226        mm->total_vm += len >> PAGE_SHIFT;
1227        vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1228        if (vm_flags & VM_LOCKED) {
1229                /*
1230                 * makes pages present; downgrades, drops, reacquires mmap_sem
1231                 */
1232                long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
1233                if (nr_pages < 0)
1234                        return nr_pages;        /* vma gone! */
1235                mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
1236        } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1237                make_pages_present(addr, addr + len);
1238        return addr;
1239
1240unmap_and_free_vma:
1241        if (correct_wcount)
1242                atomic_inc(&inode->i_writecount);
1243        vma->vm_file = NULL;
1244        fput(file);
1245
1246        /* Undo any partial mapping done by a device driver. */
1247        unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1248        charged = 0;
1249free_vma:
1250        kmem_cache_free(vm_area_cachep, vma);
1251unacct_error:
1252        if (charged)
1253                vm_unacct_memory(charged);
1254        return error;
1255}
1256
1257/* Get an address range which is currently unmapped.
1258 * For shmat() with addr=0.
1259 *
1260 * Ugly calling convention alert:
1261 * Return value with the low bits set means error value,
1262 * ie
1263 *      if (ret & ~PAGE_MASK)
1264 *              error = ret;
1265 *
1266 * This function "knows" that -ENOMEM has the bits set.
1267 */
1268#ifndef HAVE_ARCH_UNMAPPED_AREA
1269unsigned long
1270arch_get_unmapped_area(struct file *filp, unsigned long addr,
1271                unsigned long len, unsigned long pgoff, unsigned long flags)
1272{
1273        struct mm_struct *mm = current->mm;
1274        struct vm_area_struct *vma;
1275        unsigned long start_addr;
1276
1277        if (len > TASK_SIZE)
1278                return -ENOMEM;
1279
1280        if (flags & MAP_FIXED)
1281                return addr;
1282
1283        if (addr) {
1284                addr = PAGE_ALIGN(addr);
1285                vma = find_vma(mm, addr);
1286                if (TASK_SIZE - len >= addr &&
1287                    (!vma || addr + len <= vma->vm_start))
1288                        return addr;
1289        }
1290        if (len > mm->cached_hole_size) {
1291                start_addr = addr = mm->free_area_cache;
1292        } else {
1293                start_addr = addr = TASK_UNMAPPED_BASE;
1294                mm->cached_hole_size = 0;
1295        }
1296
1297full_search:
1298        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1299                /* At this point:  (!vma || addr < vma->vm_end). */
1300                if (TASK_SIZE - len < addr) {
1301                        /*
1302                         * Start a new search - just in case we missed
1303                         * some holes.
1304                         */
1305                        if (start_addr != TASK_UNMAPPED_BASE) {
1306                                addr = TASK_UNMAPPED_BASE;
1307                                start_addr = addr;
1308                                mm->cached_hole_size = 0;
1309                                goto full_search;
1310                        }
1311                        return -ENOMEM;
1312                }
1313                if (!vma || addr + len <= vma->vm_start) {
1314                        /*
1315                         * Remember the place where we stopped the search:
1316                         */
1317                        mm->free_area_cache = addr + len;
1318                        return addr;
1319                }
1320                if (addr + mm->cached_hole_size < vma->vm_start)
1321                        mm->cached_hole_size = vma->vm_start - addr;
1322                addr = vma->vm_end;
1323        }
1324}
1325#endif  
1326
1327void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1328{
1329        /*
1330         * Is this a new hole at the lowest possible address?
1331         */
1332        if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1333                mm->free_area_cache = addr;
1334                mm->cached_hole_size = ~0UL;
1335        }
1336}
1337
1338/*
1339 * This mmap-allocator allocates new areas top-down from below the
1340 * stack's low limit (the base):
1341 */
1342#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1343unsigned long
1344arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1345                          const unsigned long len, const unsigned long pgoff,
1346                          const unsigned long flags)
1347{
1348        struct vm_area_struct *vma;
1349        struct mm_struct *mm = current->mm;
1350        unsigned long addr = addr0;
1351
1352        /* requested length too big for entire address space */
1353        if (len > TASK_SIZE)
1354                return -ENOMEM;
1355
1356        if (flags & MAP_FIXED)
1357                return addr;
1358
1359        /* requesting a specific address */
1360        if (addr) {
1361                addr = PAGE_ALIGN(addr);
1362                vma = find_vma(mm, addr);
1363                if (TASK_SIZE - len >= addr &&
1364                                (!vma || addr + len <= vma->vm_start))
1365                        return addr;
1366        }
1367
1368        /* check if free_area_cache is useful for us */
1369        if (len <= mm->cached_hole_size) {
1370                mm->cached_hole_size = 0;
1371                mm->free_area_cache = mm->mmap_base;
1372        }
1373
1374        /* either no address requested or can't fit in requested address hole */
1375        addr = mm->free_area_cache;
1376
1377        /* make sure it can fit in the remaining address space */
1378        if (addr > len) {
1379                vma = find_vma(mm, addr-len);
1380                if (!vma || addr <= vma->vm_start)
1381                        /* remember the address as a hint for next time */
1382                        return (mm->free_area_cache = addr-len);
1383        }
1384
1385        if (mm->mmap_base < len)
1386                goto bottomup;
1387
1388        addr = mm->mmap_base-len;
1389
1390        do {
1391                /*
1392                 * Lookup failure means no vma is above this address,
1393                 * else if new region fits below vma->vm_start,
1394                 * return with success:
1395                 */
1396                vma = find_vma(mm, addr);
1397                if (!vma || addr+len <= vma->vm_start)
1398                        /* remember the address as a hint for next time */
1399                        return (mm->free_area_cache = addr);
1400
1401                /* remember the largest hole we saw so far */
1402                if (addr + mm->cached_hole_size < vma->vm_start)
1403                        mm->cached_hole_size = vma->vm_start - addr;
1404
1405                /* try just below the current vma->vm_start */
1406                addr = vma->vm_start-len;
1407        } while (len < vma->vm_start);
1408
1409bottomup:
1410        /*
1411         * A failed mmap() very likely causes application failure,
1412         * so fall back to the bottom-up function here. This scenario
1413         * can happen with large stack limits and large mmap()
1414         * allocations.
1415         */
1416        mm->cached_hole_size = ~0UL;
1417        mm->free_area_cache = TASK_UNMAPPED_BASE;
1418        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1419        /*
1420         * Restore the topdown base:
1421         */
1422        mm->free_area_cache = mm->mmap_base;
1423        mm->cached_hole_size = ~0UL;
1424
1425        return addr;
1426}
1427#endif
1428
1429void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1430{
1431        /*
1432         * Is this a new hole at the highest possible address?
1433         */
1434        if (addr > mm->free_area_cache)
1435                mm->free_area_cache = addr;
1436
1437        /* dont allow allocations above current base */
1438        if (mm->free_area_cache > mm->mmap_base)
1439                mm->free_area_cache = mm->mmap_base;
1440}
1441
1442unsigned long
1443get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1444                unsigned long pgoff, unsigned long flags)
1445{
1446        unsigned long (*get_area)(struct file *, unsigned long,
1447                                  unsigned long, unsigned long, unsigned long);
1448
1449        get_area = current->mm->get_unmapped_area;
1450        if (file && file->f_op && file->f_op->get_unmapped_area)
1451                get_area = file->f_op->get_unmapped_area;
1452        addr = get_area(file, addr, len, pgoff, flags);
1453        if (IS_ERR_VALUE(addr))
1454                return addr;
1455
1456        if (addr > TASK_SIZE - len)
1457                return -ENOMEM;
1458        if (addr & ~PAGE_MASK)
1459                return -EINVAL;
1460
1461        return arch_rebalance_pgtables(addr, len);
1462}
1463
1464EXPORT_SYMBOL(get_unmapped_area);
1465
1466/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1467struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1468{
1469        struct vm_area_struct *vma = NULL;
1470
1471        if (mm) {
1472                /* Check the cache first. */
1473                /* (Cache hit rate is typically around 35%.) */
1474                vma = mm->mmap_cache;
1475                if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1476                        struct rb_node * rb_node;
1477
1478                        rb_node = mm->mm_rb.rb_node;
1479                        vma = NULL;
1480
1481                        while (rb_node) {
1482                                struct vm_area_struct * vma_tmp;
1483
1484                                vma_tmp = rb_entry(rb_node,
1485                                                struct vm_area_struct, vm_rb);
1486
1487                                if (vma_tmp->vm_end > addr) {
1488                                        vma = vma_tmp;
1489                                        if (vma_tmp->vm_start <= addr)
1490                                                break;
1491                                        rb_node = rb_node->rb_left;
1492                                } else
1493                                        rb_node = rb_node->rb_right;
1494                        }
1495                        if (vma)
1496                                mm->mmap_cache = vma;
1497                }
1498        }
1499        return vma;
1500}
1501
1502EXPORT_SYMBOL(find_vma);
1503
1504/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1505struct vm_area_struct *
1506find_vma_prev(struct mm_struct *mm, unsigned long addr,
1507                        struct vm_area_struct **pprev)
1508{
1509        struct vm_area_struct *vma = NULL, *prev = NULL;
1510        struct rb_node * rb_node;
1511        if (!mm)
1512                goto out;
1513
1514        /* Guard against addr being lower than the first VMA */
1515        vma = mm->mmap;
1516
1517        /* Go through the RB tree quickly. */
1518        rb_node = mm->mm_rb.rb_node;
1519
1520        while (rb_node) {
1521                struct vm_area_struct *vma_tmp;
1522                vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1523
1524                if (addr < vma_tmp->vm_end) {
1525                        rb_node = rb_node->rb_left;
1526                } else {
1527                        prev = vma_tmp;
1528                        if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1529                                break;
1530                        rb_node = rb_node->rb_right;
1531                }
1532        }
1533
1534out:
1535        *pprev = prev;
1536        return prev ? prev->vm_next : vma;
1537}
1538
1539/*
1540 * Verify that the stack growth is acceptable and
1541 * update accounting. This is shared with both the
1542 * grow-up and grow-down cases.
1543 */
1544static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1545{
1546        struct mm_struct *mm = vma->vm_mm;
1547        struct rlimit *rlim = current->signal->rlim;
1548        unsigned long new_start;
1549
1550        /* address space limit tests */
1551        if (!may_expand_vm(mm, grow))
1552                return -ENOMEM;
1553
1554        /* Stack limit test */
1555        if (size > rlim[RLIMIT_STACK].rlim_cur)
1556                return -ENOMEM;
1557
1558        /* mlock limit tests */
1559        if (vma->vm_flags & VM_LOCKED) {
1560                unsigned long locked;
1561                unsigned long limit;
1562                locked = mm->locked_vm + grow;
1563                limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1564                if (locked > limit && !capable(CAP_IPC_LOCK))
1565                        return -ENOMEM;
1566        }
1567
1568        /* Check to ensure the stack will not grow into a hugetlb-only region */
1569        new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1570                        vma->vm_end - size;
1571        if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1572                return -EFAULT;
1573
1574        /*
1575         * Overcommit..  This must be the final test, as it will
1576         * update security statistics.
1577         */
1578        if (security_vm_enough_memory(grow))
1579                return -ENOMEM;
1580
1581        /* Ok, everything looks good - let it rip */
1582        mm->total_vm += grow;
1583        if (vma->vm_flags & VM_LOCKED)
1584                mm->locked_vm += grow;
1585        vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1586        return 0;
1587}
1588
1589#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1590/*
1591 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1592 * vma is the last one with address > vma->vm_end.  Have to extend vma.
1593 */
1594#ifndef CONFIG_IA64
1595static
1596#endif
1597int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1598{
1599        int error;
1600
1601        if (!(vma->vm_flags & VM_GROWSUP))
1602                return -EFAULT;
1603
1604        /*
1605         * We must make sure the anon_vma is allocated
1606         * so that the anon_vma locking is not a noop.
1607         */
1608        if (unlikely(anon_vma_prepare(vma)))
1609                return -ENOMEM;
1610        anon_vma_lock(vma);
1611
1612        /*
1613         * vma->vm_start/vm_end cannot change under us because the caller
1614         * is required to hold the mmap_sem in read mode.  We need the
1615         * anon_vma lock to serialize against concurrent expand_stacks.
1616         * Also guard against wrapping around to address 0.
1617         */
1618        if (address < PAGE_ALIGN(address+4))
1619                address = PAGE_ALIGN(address+4);
1620        else {
1621                anon_vma_unlock(vma);
1622                return -ENOMEM;
1623        }
1624        error = 0;
1625
1626        /* Somebody else might have raced and expanded it already */
1627        if (address > vma->vm_end) {
1628                unsigned long size, grow;
1629
1630                size = address - vma->vm_start;
1631                grow = (address - vma->vm_end) >> PAGE_SHIFT;
1632
1633                error = acct_stack_growth(vma, size, grow);
1634                if (!error)
1635                        vma->vm_end = address;
1636        }
1637        anon_vma_unlock(vma);
1638        return error;
1639}
1640#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1641
1642/*
1643 * vma is the first one with address < vma->vm_start.  Have to extend vma.
1644 */
1645static int expand_downwards(struct vm_area_struct *vma,
1646                                   unsigned long address)
1647{
1648        int error;
1649
1650        /*
1651         * We must make sure the anon_vma is allocated
1652         * so that the anon_vma locking is not a noop.
1653         */
1654        if (unlikely(anon_vma_prepare(vma)))
1655                return -ENOMEM;
1656
1657        address &= PAGE_MASK;
1658        error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1659        if (error)
1660                return error;
1661
1662        anon_vma_lock(vma);
1663
1664        /*
1665         * vma->vm_start/vm_end cannot change under us because the caller
1666         * is required to hold the mmap_sem in read mode.  We need the
1667         * anon_vma lock to serialize against concurrent expand_stacks.
1668         */
1669
1670        /* Somebody else might have raced and expanded it already */
1671        if (address < vma->vm_start) {
1672                unsigned long size, grow;
1673
1674                size = vma->vm_end - address;
1675                grow = (vma->vm_start - address) >> PAGE_SHIFT;
1676
1677                error = acct_stack_growth(vma, size, grow);
1678                if (!error) {
1679                        vma->vm_start = address;
1680                        vma->vm_pgoff -= grow;
1681                }
1682        }
1683        anon_vma_unlock(vma);
1684        return error;
1685}
1686
1687int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1688{
1689        return expand_downwards(vma, address);
1690}
1691
1692#ifdef CONFIG_STACK_GROWSUP
1693int expand_stack(struct vm_area_struct *vma, unsigned long address)
1694{
1695        return expand_upwards(vma, address);
1696}
1697
1698struct vm_area_struct *
1699find_extend_vma(struct mm_struct *mm, unsigned long addr)
1700{
1701        struct vm_area_struct *vma, *prev;
1702
1703        addr &= PAGE_MASK;
1704        vma = find_vma_prev(mm, addr, &prev);
1705        if (vma && (vma->vm_start <= addr))
1706                return vma;
1707        if (!prev || expand_stack(prev, addr))
1708                return NULL;
1709        if (prev->vm_flags & VM_LOCKED) {
1710                if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
1711                        return NULL;    /* vma gone! */
1712        }
1713        return prev;
1714}
1715#else
1716int expand_stack(struct vm_area_struct *vma, unsigned long address)
1717{
1718        return expand_downwards(vma, address);
1719}
1720
1721struct vm_area_struct *
1722find_extend_vma(struct mm_struct * mm, unsigned long addr)
1723{
1724        struct vm_area_struct * vma;
1725        unsigned long start;
1726
1727        addr &= PAGE_MASK;
1728        vma = find_vma(mm,addr);
1729        if (!vma)
1730                return NULL;
1731        if (vma->vm_start <= addr)
1732                return vma;
1733        if (!(vma->vm_flags & VM_GROWSDOWN))
1734                return NULL;
1735        start = vma->vm_start;
1736        if (expand_stack(vma, addr))
1737                return NULL;
1738        if (vma->vm_flags & VM_LOCKED) {
1739                if (mlock_vma_pages_range(vma, addr, start) < 0)
1740                        return NULL;    /* vma gone! */
1741        }
1742        return vma;
1743}
1744#endif
1745
1746/*
1747 * Ok - we have the memory areas we should free on the vma list,
1748 * so release them, and do the vma updates.
1749 *
1750 * Called with the mm semaphore held.
1751 */
1752static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1753{
1754        /* Update high watermark before we lower total_vm */
1755        update_hiwater_vm(mm);
1756        do {
1757                long nrpages = vma_pages(vma);
1758
1759                mm->total_vm -= nrpages;
1760                vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1761                vma = remove_vma(vma);
1762        } while (vma);
1763        validate_mm(mm);
1764}
1765
1766/*
1767 * Get rid of page table information in the indicated region.
1768 *
1769 * Called with the mm semaphore held.
1770 */
1771static void unmap_region(struct mm_struct *mm,
1772                struct vm_area_struct *vma, struct vm_area_struct *prev,
1773                unsigned long start, unsigned long end)
1774{
1775        struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1776        struct mmu_gather *tlb;
1777        unsigned long nr_accounted = 0;
1778
1779        lru_add_drain();
1780        tlb = tlb_gather_mmu(mm, 0);
1781        update_hiwater_rss(mm);
1782        unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1783        vm_unacct_memory(nr_accounted);
1784        free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1785                                 next? next->vm_start: 0);
1786        tlb_finish_mmu(tlb, start, end);
1787}
1788
1789/*
1790 * Create a list of vma's touched by the unmap, removing them from the mm's
1791 * vma list as we go..
1792 */
1793static void
1794detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1795        struct vm_area_struct *prev, unsigned long end)
1796{
1797        struct vm_area_struct **insertion_point;
1798        struct vm_area_struct *tail_vma = NULL;
1799        unsigned long addr;
1800
1801        insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1802        do {
1803                rb_erase(&vma->vm_rb, &mm->mm_rb);
1804                mm->map_count--;
1805                tail_vma = vma;
1806                vma = vma->vm_next;
1807        } while (vma && vma->vm_start < end);
1808        *insertion_point = vma;
1809        tail_vma->vm_next = NULL;
1810        if (mm->unmap_area == arch_unmap_area)
1811                addr = prev ? prev->vm_end : mm->mmap_base;
1812        else
1813                addr = vma ?  vma->vm_start : mm->mmap_base;
1814        mm->unmap_area(mm, addr);
1815        mm->mmap_cache = NULL;          /* Kill the cache. */
1816}
1817
1818/*
1819 * Split a vma into two pieces at address 'addr', a new vma is allocated
1820 * either for the first part or the tail.
1821 */
1822int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1823              unsigned long addr, int new_below)
1824{
1825        struct mempolicy *pol;
1826        struct vm_area_struct *new;
1827
1828        if (is_vm_hugetlb_page(vma) && (addr &
1829                                        ~(huge_page_mask(hstate_vma(vma)))))
1830                return -EINVAL;
1831
1832        if (mm->map_count >= sysctl_max_map_count)
1833                return -ENOMEM;
1834
1835        new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1836        if (!new)
1837                return -ENOMEM;
1838
1839        /* most fields are the same, copy all, and then fixup */
1840        *new = *vma;
1841
1842        if (new_below)
1843                new->vm_end = addr;
1844        else {
1845                new->vm_start = addr;
1846                new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1847        }
1848
1849        pol = mpol_dup(vma_policy(vma));
1850        if (IS_ERR(pol)) {
1851                kmem_cache_free(vm_area_cachep, new);
1852                return PTR_ERR(pol);
1853        }
1854        vma_set_policy(new, pol);
1855
1856        if (new->vm_file) {
1857                get_file(new->vm_file);
1858                if (vma->vm_flags & VM_EXECUTABLE)
1859                        added_exe_file_vma(mm);
1860        }
1861
1862        if (new->vm_ops && new->vm_ops->open)
1863                new->vm_ops->open(new);
1864
1865        if (new_below)
1866                vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1867                        ((addr - new->vm_start) >> PAGE_SHIFT), new);
1868        else
1869                vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1870
1871        return 0;
1872}
1873
1874/* Munmap is split into 2 main parts -- this part which finds
1875 * what needs doing, and the areas themselves, which do the
1876 * work.  This now handles partial unmappings.
1877 * Jeremy Fitzhardinge <jeremy@goop.org>
1878 */
1879int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1880{
1881        unsigned long end;
1882        struct vm_area_struct *vma, *prev, *last;
1883
1884        if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1885                return -EINVAL;
1886
1887        if ((len = PAGE_ALIGN(len)) == 0)
1888                return -EINVAL;
1889
1890        /* Find the first overlapping VMA */
1891        vma = find_vma_prev(mm, start, &prev);
1892        if (!vma)
1893                return 0;
1894        /* we have  start < vma->vm_end  */
1895
1896        /* if it doesn't overlap, we have nothing.. */
1897        end = start + len;
1898        if (vma->vm_start >= end)
1899                return 0;
1900
1901        /*
1902         * If we need to split any vma, do it now to save pain later.
1903         *
1904         * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1905         * unmapped vm_area_struct will remain in use: so lower split_vma
1906         * places tmp vma above, and higher split_vma places tmp vma below.
1907         */
1908        if (start > vma->vm_start) {
1909                int error = split_vma(mm, vma, start, 0);
1910                if (error)
1911                        return error;
1912                prev = vma;
1913        }
1914
1915        /* Does it split the last one? */
1916        last = find_vma(mm, end);
1917        if (last && end > last->vm_start) {
1918                int error = split_vma(mm, last, end, 1);
1919                if (error)
1920                        return error;
1921        }
1922        vma = prev? prev->vm_next: mm->mmap;
1923
1924        /*
1925         * unlock any mlock()ed ranges before detaching vmas
1926         */
1927        if (mm->locked_vm) {
1928                struct vm_area_struct *tmp = vma;
1929                while (tmp && tmp->vm_start < end) {
1930                        if (tmp->vm_flags & VM_LOCKED) {
1931                                mm->locked_vm -= vma_pages(tmp);
1932                                munlock_vma_pages_all(tmp);
1933                        }
1934                        tmp = tmp->vm_next;
1935                }
1936        }
1937
1938        /*
1939         * Remove the vma's, and unmap the actual pages
1940         */
1941        detach_vmas_to_be_unmapped(mm, vma, prev, end);
1942        unmap_region(mm, vma, prev, start, end);
1943
1944        /* Fix up all other VM information */
1945        remove_vma_list(mm, vma);
1946
1947        return 0;
1948}
1949
1950EXPORT_SYMBOL(do_munmap);
1951
1952asmlinkage long sys_munmap(unsigned long addr, size_t len)
1953{
1954        int ret;
1955        struct mm_struct *mm = current->mm;
1956
1957        profile_munmap(addr);
1958
1959        down_write(&mm->mmap_sem);
1960        ret = do_munmap(mm, addr, len);
1961        up_write(&mm->mmap_sem);
1962        return ret;
1963}
1964
1965static inline void verify_mm_writelocked(struct mm_struct *mm)
1966{
1967#ifdef CONFIG_DEBUG_VM
1968        if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1969                WARN_ON(1);
1970                up_read(&mm->mmap_sem);
1971        }
1972#endif
1973}
1974
1975/*
1976 *  this is really a simplified "do_mmap".  it only handles
1977 *  anonymous maps.  eventually we may be able to do some
1978 *  brk-specific accounting here.
1979 */
1980unsigned long do_brk(unsigned long addr, unsigned long len)
1981{
1982        struct mm_struct * mm = current->mm;
1983        struct vm_area_struct * vma, * prev;
1984        unsigned long flags;
1985        struct rb_node ** rb_link, * rb_parent;
1986        pgoff_t pgoff = addr >> PAGE_SHIFT;
1987        int error;
1988
1989        len = PAGE_ALIGN(len);
1990        if (!len)
1991                return addr;
1992
1993        if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1994                return -EINVAL;
1995
1996        if (is_hugepage_only_range(mm, addr, len))
1997                return -EINVAL;
1998
1999        error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2000        if (error)
2001                return error;
2002
2003        flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2004
2005        error = arch_mmap_check(addr, len, flags);
2006        if (error)
2007                return error;
2008
2009        /*
2010         * mlock MCL_FUTURE?
2011         */
2012        if (mm->def_flags & VM_LOCKED) {
2013                unsigned long locked, lock_limit;
2014                locked = len >> PAGE_SHIFT;
2015                locked += mm->locked_vm;
2016                lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
2017                lock_limit >>= PAGE_SHIFT;
2018                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2019                        return -EAGAIN;
2020        }
2021
2022        /*
2023         * mm->mmap_sem is required to protect against another thread
2024         * changing the mappings in case we sleep.
2025         */
2026        verify_mm_writelocked(mm);
2027
2028        /*
2029         * Clear old maps.  this also does some error checking for us
2030         */
2031 munmap_back:
2032        vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2033        if (vma && vma->vm_start < addr + len) {
2034                if (do_munmap(mm, addr, len))
2035                        return -ENOMEM;
2036                goto munmap_back;
2037        }
2038
2039        /* Check against address space limits *after* clearing old maps... */
2040        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2041                return -ENOMEM;
2042
2043        if (mm->map_count > sysctl_max_map_count)
2044                return -ENOMEM;
2045
2046        if (security_vm_enough_memory(len >> PAGE_SHIFT))
2047                return -ENOMEM;
2048
2049        /* Can we just expand an old private anonymous mapping? */
2050        vma = vma_merge(mm, prev, addr, addr + len, flags,
2051                                        NULL, NULL, pgoff, NULL);
2052        if (vma)
2053                goto out;
2054
2055        /*
2056         * create a vma struct for an anonymous mapping
2057         */
2058        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2059        if (!vma) {
2060                vm_unacct_memory(len >> PAGE_SHIFT);
2061                return -ENOMEM;
2062        }
2063
2064        vma->vm_mm = mm;
2065        vma->vm_start = addr;
2066        vma->vm_end = addr + len;
2067        vma->vm_pgoff = pgoff;
2068        vma->vm_flags = flags;
2069        vma->vm_page_prot = vm_get_page_prot(flags);
2070        vma_link(mm, vma, prev, rb_link, rb_parent);
2071out:
2072        mm->total_vm += len >> PAGE_SHIFT;
2073        if (flags & VM_LOCKED) {
2074                if (!mlock_vma_pages_range(vma, addr, addr + len))
2075                        mm->locked_vm += (len >> PAGE_SHIFT);
2076        }
2077        return addr;
2078}
2079
2080EXPORT_SYMBOL(do_brk);
2081
2082/* Release all mmaps. */
2083void exit_mmap(struct mm_struct *mm)
2084{
2085        struct mmu_gather *tlb;
2086        struct vm_area_struct *vma;
2087        unsigned long nr_accounted = 0;
2088        unsigned long end;
2089
2090        /* mm's last user has gone, and its about to be pulled down */
2091        arch_exit_mmap(mm);
2092        mmu_notifier_release(mm);
2093
2094        if (mm->locked_vm) {
2095                vma = mm->mmap;
2096                while (vma) {
2097                        if (vma->vm_flags & VM_LOCKED)
2098                                munlock_vma_pages_all(vma);
2099                        vma = vma->vm_next;
2100                }
2101        }
2102        vma = mm->mmap;
2103        lru_add_drain();
2104        flush_cache_mm(mm);
2105        tlb = tlb_gather_mmu(mm, 1);
2106        /* Don't update_hiwater_rss(mm) here, do_exit already did */
2107        /* Use -1 here to ensure all VMAs in the mm are unmapped */
2108        end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2109        vm_unacct_memory(nr_accounted);
2110        free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2111        tlb_finish_mmu(tlb, 0, end);
2112
2113        /*
2114         * Walk the list again, actually closing and freeing it,
2115         * with preemption enabled, without holding any MM locks.
2116         */
2117        while (vma)
2118                vma = remove_vma(vma);
2119
2120        BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2121}
2122
2123/* Insert vm structure into process list sorted by address
2124 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2125 * then i_mmap_lock is taken here.
2126 */
2127int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2128{
2129        struct vm_area_struct * __vma, * prev;
2130        struct rb_node ** rb_link, * rb_parent;
2131
2132        /*
2133         * The vm_pgoff of a purely anonymous vma should be irrelevant
2134         * until its first write fault, when page's anon_vma and index
2135         * are set.  But now set the vm_pgoff it will almost certainly
2136         * end up with (unless mremap moves it elsewhere before that
2137         * first wfault), so /proc/pid/maps tells a consistent story.
2138         *
2139         * By setting it to reflect the virtual start address of the
2140         * vma, merges and splits can happen in a seamless way, just
2141         * using the existing file pgoff checks and manipulations.
2142         * Similarly in do_mmap_pgoff and in do_brk.
2143         */
2144        if (!vma->vm_file) {
2145                BUG_ON(vma->anon_vma);
2146                vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2147        }
2148        __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2149        if (__vma && __vma->vm_start < vma->vm_end)
2150                return -ENOMEM;
2151        if ((vma->vm_flags & VM_ACCOUNT) &&
2152             security_vm_enough_memory_mm(mm, vma_pages(vma)))
2153                return -ENOMEM;
2154        vma_link(mm, vma, prev, rb_link, rb_parent);
2155        return 0;
2156}
2157
2158/*
2159 * Copy the vma structure to a new location in the same mm,
2160 * prior to moving page table entries, to effect an mremap move.
2161 */
2162struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2163        unsigned long addr, unsigned long len, pgoff_t pgoff)
2164{
2165        struct vm_area_struct *vma = *vmap;
2166        unsigned long vma_start = vma->vm_start;
2167        struct mm_struct *mm = vma->vm_mm;
2168        struct vm_area_struct *new_vma, *prev;
2169        struct rb_node **rb_link, *rb_parent;
2170        struct mempolicy *pol;
2171
2172        /*
2173         * If anonymous vma has not yet been faulted, update new pgoff
2174         * to match new location, to increase its chance of merging.
2175         */
2176        if (!vma->vm_file && !vma->anon_vma)
2177                pgoff = addr >> PAGE_SHIFT;
2178
2179        find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2180        new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2181                        vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2182        if (new_vma) {
2183                /*
2184                 * Source vma may have been merged into new_vma
2185                 */
2186                if (vma_start >= new_vma->vm_start &&
2187                    vma_start < new_vma->vm_end)
2188                        *vmap = new_vma;
2189        } else {
2190                new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2191                if (new_vma) {
2192                        *new_vma = *vma;
2193                        pol = mpol_dup(vma_policy(vma));
2194                        if (IS_ERR(pol)) {
2195                                kmem_cache_free(vm_area_cachep, new_vma);
2196                                return NULL;
2197                        }
2198                        vma_set_policy(new_vma, pol);
2199                        new_vma->vm_start = addr;
2200                        new_vma->vm_end = addr + len;
2201                        new_vma->vm_pgoff = pgoff;
2202                        if (new_vma->vm_file) {
2203                                get_file(new_vma->vm_file);
2204                                if (vma->vm_flags & VM_EXECUTABLE)
2205                                        added_exe_file_vma(mm);
2206                        }
2207                        if (new_vma->vm_ops && new_vma->vm_ops->open)
2208                                new_vma->vm_ops->open(new_vma);
2209                        vma_link(mm, new_vma, prev, rb_link, rb_parent);
2210                }
2211        }
2212        return new_vma;
2213}
2214
2215/*
2216 * Return true if the calling process may expand its vm space by the passed
2217 * number of pages
2218 */
2219int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2220{
2221        unsigned long cur = mm->total_vm;       /* pages */
2222        unsigned long lim;
2223
2224        lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2225
2226        if (cur + npages > lim)
2227                return 0;
2228        return 1;
2229}
2230
2231
2232static int special_mapping_fault(struct vm_area_struct *vma,
2233                                struct vm_fault *vmf)
2234{
2235        pgoff_t pgoff;
2236        struct page **pages;
2237
2238        /*
2239         * special mappings have no vm_file, and in that case, the mm
2240         * uses vm_pgoff internally. So we have to subtract it from here.
2241         * We are allowed to do this because we are the mm; do not copy
2242         * this code into drivers!
2243         */
2244        pgoff = vmf->pgoff - vma->vm_pgoff;
2245
2246        for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2247                pgoff--;
2248
2249        if (*pages) {
2250                struct page *page = *pages;
2251                get_page(page);
2252                vmf->page = page;
2253                return 0;
2254        }
2255
2256        return VM_FAULT_SIGBUS;
2257}
2258
2259/*
2260 * Having a close hook prevents vma merging regardless of flags.
2261 */
2262static void special_mapping_close(struct vm_area_struct *vma)
2263{
2264}
2265
2266static struct vm_operations_struct special_mapping_vmops = {
2267        .close = special_mapping_close,
2268        .fault = special_mapping_fault,
2269};
2270
2271/*
2272 * Called with mm->mmap_sem held for writing.
2273 * Insert a new vma covering the given region, with the given flags.
2274 * Its pages are supplied by the given array of struct page *.
2275 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2276 * The region past the last page supplied will always produce SIGBUS.
2277 * The array pointer and the pages it points to are assumed to stay alive
2278 * for as long as this mapping might exist.
2279 */
2280int install_special_mapping(struct mm_struct *mm,
2281                            unsigned long addr, unsigned long len,
2282                            unsigned long vm_flags, struct page **pages)
2283{
2284        struct vm_area_struct *vma;
2285
2286        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2287        if (unlikely(vma == NULL))
2288                return -ENOMEM;
2289
2290        vma->vm_mm = mm;
2291        vma->vm_start = addr;
2292        vma->vm_end = addr + len;
2293
2294        vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2295        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2296
2297        vma->vm_ops = &special_mapping_vmops;
2298        vma->vm_private_data = pages;
2299
2300        if (unlikely(insert_vm_struct(mm, vma))) {
2301                kmem_cache_free(vm_area_cachep, vma);
2302                return -ENOMEM;
2303        }
2304
2305        mm->total_vm += len >> PAGE_SHIFT;
2306
2307        return 0;
2308}
2309
2310static DEFINE_MUTEX(mm_all_locks_mutex);
2311
2312static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2313{
2314        if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2315                /*
2316                 * The LSB of head.next can't change from under us
2317                 * because we hold the mm_all_locks_mutex.
2318                 */
2319                spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
2320                /*
2321                 * We can safely modify head.next after taking the
2322                 * anon_vma->lock. If some other vma in this mm shares
2323                 * the same anon_vma we won't take it again.
2324                 *
2325                 * No need of atomic instructions here, head.next
2326                 * can't change from under us thanks to the
2327                 * anon_vma->lock.
2328                 */
2329                if (__test_and_set_bit(0, (unsigned long *)
2330                                       &anon_vma->head.next))
2331                        BUG();
2332        }
2333}
2334
2335static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2336{
2337        if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2338                /*
2339                 * AS_MM_ALL_LOCKS can't change from under us because
2340                 * we hold the mm_all_locks_mutex.
2341                 *
2342                 * Operations on ->flags have to be atomic because
2343                 * even if AS_MM_ALL_LOCKS is stable thanks to the
2344                 * mm_all_locks_mutex, there may be other cpus
2345                 * changing other bitflags in parallel to us.
2346                 */
2347                if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2348                        BUG();
2349                spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2350        }
2351}
2352
2353/*
2354 * This operation locks against the VM for all pte/vma/mm related
2355 * operations that could ever happen on a certain mm. This includes
2356 * vmtruncate, try_to_unmap, and all page faults.
2357 *
2358 * The caller must take the mmap_sem in write mode before calling
2359 * mm_take_all_locks(). The caller isn't allowed to release the
2360 * mmap_sem until mm_drop_all_locks() returns.
2361 *
2362 * mmap_sem in write mode is required in order to block all operations
2363 * that could modify pagetables and free pages without need of
2364 * altering the vma layout (for example populate_range() with
2365 * nonlinear vmas). It's also needed in write mode to avoid new
2366 * anon_vmas to be associated with existing vmas.
2367 *
2368 * A single task can't take more than one mm_take_all_locks() in a row
2369 * or it would deadlock.
2370 *
2371 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2372 * mapping->flags avoid to take the same lock twice, if more than one
2373 * vma in this mm is backed by the same anon_vma or address_space.
2374 *
2375 * We can take all the locks in random order because the VM code
2376 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2377 * takes more than one of them in a row. Secondly we're protected
2378 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2379 *
2380 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2381 * that may have to take thousand of locks.
2382 *
2383 * mm_take_all_locks() can fail if it's interrupted by signals.
2384 */
2385int mm_take_all_locks(struct mm_struct *mm)
2386{
2387        struct vm_area_struct *vma;
2388        int ret = -EINTR;
2389
2390        BUG_ON(down_read_trylock(&mm->mmap_sem));
2391
2392        mutex_lock(&mm_all_locks_mutex);
2393
2394        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2395                if (signal_pending(current))
2396                        goto out_unlock;
2397                if (vma->vm_file && vma->vm_file->f_mapping)
2398                        vm_lock_mapping(mm, vma->vm_file->f_mapping);
2399        }
2400
2401        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2402                if (signal_pending(current))
2403                        goto out_unlock;
2404                if (vma->anon_vma)
2405                        vm_lock_anon_vma(mm, vma->anon_vma);
2406        }
2407
2408        ret = 0;
2409
2410out_unlock:
2411        if (ret)
2412                mm_drop_all_locks(mm);
2413
2414        return ret;
2415}
2416
2417static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2418{
2419        if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
2420                /*
2421                 * The LSB of head.next can't change to 0 from under
2422                 * us because we hold the mm_all_locks_mutex.
2423                 *
2424                 * We must however clear the bitflag before unlocking
2425                 * the vma so the users using the anon_vma->head will
2426                 * never see our bitflag.
2427                 *
2428                 * No need of atomic instructions here, head.next
2429                 * can't change from under us until we release the
2430                 * anon_vma->lock.
2431                 */
2432                if (!__test_and_clear_bit(0, (unsigned long *)
2433                                          &anon_vma->head.next))
2434                        BUG();
2435                spin_unlock(&anon_vma->lock);
2436        }
2437}
2438
2439static void vm_unlock_mapping(struct address_space *mapping)
2440{
2441        if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2442                /*
2443                 * AS_MM_ALL_LOCKS can't change to 0 from under us
2444                 * because we hold the mm_all_locks_mutex.
2445                 */
2446                spin_unlock(&mapping->i_mmap_lock);
2447                if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2448                                        &mapping->flags))
2449                        BUG();
2450        }
2451}
2452
2453/*
2454 * The mmap_sem cannot be released by the caller until
2455 * mm_drop_all_locks() returns.
2456 */
2457void mm_drop_all_locks(struct mm_struct *mm)
2458{
2459        struct vm_area_struct *vma;
2460
2461        BUG_ON(down_read_trylock(&mm->mmap_sem));
2462        BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2463
2464        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2465                if (vma->anon_vma)
2466                        vm_unlock_anon_vma(vma->anon_vma);
2467                if (vma->vm_file && vma->vm_file->f_mapping)
2468                        vm_unlock_mapping(vma->vm_file->f_mapping);
2469        }
2470
2471        mutex_unlock(&mm_all_locks_mutex);
2472}
2473
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