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@lxorguk.ukuu.org.uk>
   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/export.h>
  26#include <linux/mount.h>
  27#include <linux/mempolicy.h>
  28#include <linux/rmap.h>
  29#include <linux/mmu_notifier.h>
  30#include <linux/perf_event.h>
  31#include <linux/audit.h>
  32#include <linux/khugepaged.h>
  33#include <linux/uprobes.h>
  34#include <linux/rbtree_augmented.h>
  35#include <linux/sched/sysctl.h>
  36
  37#include <asm/uaccess.h>
  38#include <asm/cacheflush.h>
  39#include <asm/tlb.h>
  40#include <asm/mmu_context.h>
  41
  42#include "internal.h"
  43
  44#ifndef arch_mmap_check
  45#define arch_mmap_check(addr, len, flags)       (0)
  46#endif
  47
  48#ifndef arch_rebalance_pgtables
  49#define arch_rebalance_pgtables(addr, len)              (addr)
  50#endif
  51
  52static void unmap_region(struct mm_struct *mm,
  53                struct vm_area_struct *vma, struct vm_area_struct *prev,
  54                unsigned long start, unsigned long end);
  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 __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
  85int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
  86int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
  87/*
  88 * Make sure vm_committed_as in one cacheline and not cacheline shared with
  89 * other variables. It can be updated by several CPUs frequently.
  90 */
  91struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
  92
  93/*
  94 * The global memory commitment made in the system can be a metric
  95 * that can be used to drive ballooning decisions when Linux is hosted
  96 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
  97 * balancing memory across competing virtual machines that are hosted.
  98 * Several metrics drive this policy engine including the guest reported
  99 * memory commitment.
 100 */
 101unsigned long vm_memory_committed(void)
 102{
 103        return percpu_counter_read_positive(&vm_committed_as);
 104}
 105EXPORT_SYMBOL_GPL(vm_memory_committed);
 106
 107/*
 108 * Check that a process has enough memory to allocate a new virtual
 109 * mapping. 0 means there is enough memory for the allocation to
 110 * succeed and -ENOMEM implies there is not.
 111 *
 112 * We currently support three overcommit policies, which are set via the
 113 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
 114 *
 115 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 116 * Additional code 2002 Jul 20 by Robert Love.
 117 *
 118 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 119 *
 120 * Note this is a helper function intended to be used by LSMs which
 121 * wish to use this logic.
 122 */
 123int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
 124{
 125        unsigned long free, allowed;
 126
 127        vm_acct_memory(pages);
 128
 129        /*
 130         * Sometimes we want to use more memory than we have
 131         */
 132        if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
 133                return 0;
 134
 135        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
 136                free = global_page_state(NR_FREE_PAGES);
 137                free += global_page_state(NR_FILE_PAGES);
 138
 139                /*
 140                 * shmem pages shouldn't be counted as free in this
 141                 * case, they can't be purged, only swapped out, and
 142                 * that won't affect the overall amount of available
 143                 * memory in the system.
 144                 */
 145                free -= global_page_state(NR_SHMEM);
 146
 147                free += get_nr_swap_pages();
 148
 149                /*
 150                 * Any slabs which are created with the
 151                 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
 152                 * which are reclaimable, under pressure.  The dentry
 153                 * cache and most inode caches should fall into this
 154                 */
 155                free += global_page_state(NR_SLAB_RECLAIMABLE);
 156
 157                /*
 158                 * Leave reserved pages. The pages are not for anonymous pages.
 159                 */
 160                if (free <= totalreserve_pages)
 161                        goto error;
 162                else
 163                        free -= totalreserve_pages;
 164
 165                /*
 166                 * Leave the last 3% for root
 167                 */
 168                if (!cap_sys_admin)
 169                        free -= free / 32;
 170
 171                if (free > pages)
 172                        return 0;
 173
 174                goto error;
 175        }
 176
 177        allowed = (totalram_pages - hugetlb_total_pages())
 178                * sysctl_overcommit_ratio / 100;
 179        /*
 180         * Leave the last 3% for root
 181         */
 182        if (!cap_sys_admin)
 183                allowed -= allowed / 32;
 184        allowed += total_swap_pages;
 185
 186        /* Don't let a single process grow too big:
 187           leave 3% of the size of this process for other processes */
 188        if (mm)
 189                allowed -= mm->total_vm / 32;
 190
 191        if (percpu_counter_read_positive(&vm_committed_as) < allowed)
 192                return 0;
 193error:
 194        vm_unacct_memory(pages);
 195
 196        return -ENOMEM;
 197}
 198
 199/*
 200 * Requires inode->i_mapping->i_mmap_mutex
 201 */
 202static void __remove_shared_vm_struct(struct vm_area_struct *vma,
 203                struct file *file, struct address_space *mapping)
 204{
 205        if (vma->vm_flags & VM_DENYWRITE)
 206                atomic_inc(&file_inode(file)->i_writecount);
 207        if (vma->vm_flags & VM_SHARED)
 208                mapping->i_mmap_writable--;
 209
 210        flush_dcache_mmap_lock(mapping);
 211        if (unlikely(vma->vm_flags & VM_NONLINEAR))
 212                list_del_init(&vma->shared.nonlinear);
 213        else
 214                vma_interval_tree_remove(vma, &mapping->i_mmap);
 215        flush_dcache_mmap_unlock(mapping);
 216}
 217
 218/*
 219 * Unlink a file-based vm structure from its interval tree, to hide
 220 * vma from rmap and vmtruncate before freeing its page tables.
 221 */
 222void unlink_file_vma(struct vm_area_struct *vma)
 223{
 224        struct file *file = vma->vm_file;
 225
 226        if (file) {
 227                struct address_space *mapping = file->f_mapping;
 228                mutex_lock(&mapping->i_mmap_mutex);
 229                __remove_shared_vm_struct(vma, file, mapping);
 230                mutex_unlock(&mapping->i_mmap_mutex);
 231        }
 232}
 233
 234/*
 235 * Close a vm structure and free it, returning the next.
 236 */
 237static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 238{
 239        struct vm_area_struct *next = vma->vm_next;
 240
 241        might_sleep();
 242        if (vma->vm_ops && vma->vm_ops->close)
 243                vma->vm_ops->close(vma);
 244        if (vma->vm_file)
 245                fput(vma->vm_file);
 246        mpol_put(vma_policy(vma));
 247        kmem_cache_free(vm_area_cachep, vma);
 248        return next;
 249}
 250
 251static unsigned long do_brk(unsigned long addr, unsigned long len);
 252
 253SYSCALL_DEFINE1(brk, unsigned long, brk)
 254{
 255        unsigned long rlim, retval;
 256        unsigned long newbrk, oldbrk;
 257        struct mm_struct *mm = current->mm;
 258        unsigned long min_brk;
 259        bool populate;
 260
 261        down_write(&mm->mmap_sem);
 262
 263#ifdef CONFIG_COMPAT_BRK
 264        /*
 265         * CONFIG_COMPAT_BRK can still be overridden by setting
 266         * randomize_va_space to 2, which will still cause mm->start_brk
 267         * to be arbitrarily shifted
 268         */
 269        if (current->brk_randomized)
 270                min_brk = mm->start_brk;
 271        else
 272                min_brk = mm->end_data;
 273#else
 274        min_brk = mm->start_brk;
 275#endif
 276        if (brk < min_brk)
 277                goto out;
 278
 279        /*
 280         * Check against rlimit here. If this check is done later after the test
 281         * of oldbrk with newbrk then it can escape the test and let the data
 282         * segment grow beyond its set limit the in case where the limit is
 283         * not page aligned -Ram Gupta
 284         */
 285        rlim = rlimit(RLIMIT_DATA);
 286        if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
 287                        (mm->end_data - mm->start_data) > rlim)
 288                goto out;
 289
 290        newbrk = PAGE_ALIGN(brk);
 291        oldbrk = PAGE_ALIGN(mm->brk);
 292        if (oldbrk == newbrk)
 293                goto set_brk;
 294
 295        /* Always allow shrinking brk. */
 296        if (brk <= mm->brk) {
 297                if (!do_munmap(mm, newbrk, oldbrk-newbrk))
 298                        goto set_brk;
 299                goto out;
 300        }
 301
 302        /* Check against existing mmap mappings. */
 303        if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
 304                goto out;
 305
 306        /* Ok, looks good - let it rip. */
 307        if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
 308                goto out;
 309
 310set_brk:
 311        mm->brk = brk;
 312        populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
 313        up_write(&mm->mmap_sem);
 314        if (populate)
 315                mm_populate(oldbrk, newbrk - oldbrk);
 316        return brk;
 317
 318out:
 319        retval = mm->brk;
 320        up_write(&mm->mmap_sem);
 321        return retval;
 322}
 323
 324static long vma_compute_subtree_gap(struct vm_area_struct *vma)
 325{
 326        unsigned long max, subtree_gap;
 327        max = vma->vm_start;
 328        if (vma->vm_prev)
 329                max -= vma->vm_prev->vm_end;
 330        if (vma->vm_rb.rb_left) {
 331                subtree_gap = rb_entry(vma->vm_rb.rb_left,
 332                                struct vm_area_struct, vm_rb)->rb_subtree_gap;
 333                if (subtree_gap > max)
 334                        max = subtree_gap;
 335        }
 336        if (vma->vm_rb.rb_right) {
 337                subtree_gap = rb_entry(vma->vm_rb.rb_right,
 338                                struct vm_area_struct, vm_rb)->rb_subtree_gap;
 339                if (subtree_gap > max)
 340                        max = subtree_gap;
 341        }
 342        return max;
 343}
 344
 345#ifdef CONFIG_DEBUG_VM_RB
 346static int browse_rb(struct rb_root *root)
 347{
 348        int i = 0, j, bug = 0;
 349        struct rb_node *nd, *pn = NULL;
 350        unsigned long prev = 0, pend = 0;
 351
 352        for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 353                struct vm_area_struct *vma;
 354                vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 355                if (vma->vm_start < prev) {
 356                        printk("vm_start %lx prev %lx\n", vma->vm_start, prev);
 357                        bug = 1;
 358                }
 359                if (vma->vm_start < pend) {
 360                        printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
 361                        bug = 1;
 362                }
 363                if (vma->vm_start > vma->vm_end) {
 364                        printk("vm_end %lx < vm_start %lx\n",
 365                                vma->vm_end, vma->vm_start);
 366                        bug = 1;
 367                }
 368                if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
 369                        printk("free gap %lx, correct %lx\n",
 370                               vma->rb_subtree_gap,
 371                               vma_compute_subtree_gap(vma));
 372                        bug = 1;
 373                }
 374                i++;
 375                pn = nd;
 376                prev = vma->vm_start;
 377                pend = vma->vm_end;
 378        }
 379        j = 0;
 380        for (nd = pn; nd; nd = rb_prev(nd))
 381                j++;
 382        if (i != j) {
 383                printk("backwards %d, forwards %d\n", j, i);
 384                bug = 1;
 385        }
 386        return bug ? -1 : i;
 387}
 388
 389static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
 390{
 391        struct rb_node *nd;
 392
 393        for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 394                struct vm_area_struct *vma;
 395                vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 396                BUG_ON(vma != ignore &&
 397                       vma->rb_subtree_gap != vma_compute_subtree_gap(vma));
 398        }
 399}
 400
 401void validate_mm(struct mm_struct *mm)
 402{
 403        int bug = 0;
 404        int i = 0;
 405        unsigned long highest_address = 0;
 406        struct vm_area_struct *vma = mm->mmap;
 407        while (vma) {
 408                struct anon_vma_chain *avc;
 409                vma_lock_anon_vma(vma);
 410                list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 411                        anon_vma_interval_tree_verify(avc);
 412                vma_unlock_anon_vma(vma);
 413                highest_address = vma->vm_end;
 414                vma = vma->vm_next;
 415                i++;
 416        }
 417        if (i != mm->map_count) {
 418                printk("map_count %d vm_next %d\n", mm->map_count, i);
 419                bug = 1;
 420        }
 421        if (highest_address != mm->highest_vm_end) {
 422                printk("mm->highest_vm_end %lx, found %lx\n",
 423                       mm->highest_vm_end, highest_address);
 424                bug = 1;
 425        }
 426        i = browse_rb(&mm->mm_rb);
 427        if (i != mm->map_count) {
 428                printk("map_count %d rb %d\n", mm->map_count, i);
 429                bug = 1;
 430        }
 431        BUG_ON(bug);
 432}
 433#else
 434#define validate_mm_rb(root, ignore) do { } while (0)
 435#define validate_mm(mm) do { } while (0)
 436#endif
 437
 438RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
 439                     unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
 440
 441/*
 442 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
 443 * vma->vm_prev->vm_end values changed, without modifying the vma's position
 444 * in the rbtree.
 445 */
 446static void vma_gap_update(struct vm_area_struct *vma)
 447{
 448        /*
 449         * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
 450         * function that does exacltly what we want.
 451         */
 452        vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
 453}
 454
 455static inline void vma_rb_insert(struct vm_area_struct *vma,
 456                                 struct rb_root *root)
 457{
 458        /* All rb_subtree_gap values must be consistent prior to insertion */
 459        validate_mm_rb(root, NULL);
 460
 461        rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
 462}
 463
 464static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
 465{
 466        /*
 467         * All rb_subtree_gap values must be consistent prior to erase,
 468         * with the possible exception of the vma being erased.
 469         */
 470        validate_mm_rb(root, vma);
 471
 472        /*
 473         * Note rb_erase_augmented is a fairly large inline function,
 474         * so make sure we instantiate it only once with our desired
 475         * augmented rbtree callbacks.
 476         */
 477        rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
 478}
 479
 480/*
 481 * vma has some anon_vma assigned, and is already inserted on that
 482 * anon_vma's interval trees.
 483 *
 484 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
 485 * vma must be removed from the anon_vma's interval trees using
 486 * anon_vma_interval_tree_pre_update_vma().
 487 *
 488 * After the update, the vma will be reinserted using
 489 * anon_vma_interval_tree_post_update_vma().
 490 *
 491 * The entire update must be protected by exclusive mmap_sem and by
 492 * the root anon_vma's mutex.
 493 */
 494static inline void
 495anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
 496{
 497        struct anon_vma_chain *avc;
 498
 499        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 500                anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
 501}
 502
 503static inline void
 504anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
 505{
 506        struct anon_vma_chain *avc;
 507
 508        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 509                anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
 510}
 511
 512static int find_vma_links(struct mm_struct *mm, unsigned long addr,
 513                unsigned long end, struct vm_area_struct **pprev,
 514                struct rb_node ***rb_link, struct rb_node **rb_parent)
 515{
 516        struct rb_node **__rb_link, *__rb_parent, *rb_prev;
 517
 518        __rb_link = &mm->mm_rb.rb_node;
 519        rb_prev = __rb_parent = NULL;
 520
 521        while (*__rb_link) {
 522                struct vm_area_struct *vma_tmp;
 523
 524                __rb_parent = *__rb_link;
 525                vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
 526
 527                if (vma_tmp->vm_end > addr) {
 528                        /* Fail if an existing vma overlaps the area */
 529                        if (vma_tmp->vm_start < end)
 530                                return -ENOMEM;
 531                        __rb_link = &__rb_parent->rb_left;
 532                } else {
 533                        rb_prev = __rb_parent;
 534                        __rb_link = &__rb_parent->rb_right;
 535                }
 536        }
 537
 538        *pprev = NULL;
 539        if (rb_prev)
 540                *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 541        *rb_link = __rb_link;
 542        *rb_parent = __rb_parent;
 543        return 0;
 544}
 545
 546void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 547                struct rb_node **rb_link, struct rb_node *rb_parent)
 548{
 549        /* Update tracking information for the gap following the new vma. */
 550        if (vma->vm_next)
 551                vma_gap_update(vma->vm_next);
 552        else
 553                mm->highest_vm_end = vma->vm_end;
 554
 555        /*
 556         * vma->vm_prev wasn't known when we followed the rbtree to find the
 557         * correct insertion point for that vma. As a result, we could not
 558         * update the vma vm_rb parents rb_subtree_gap values on the way down.
 559         * So, we first insert the vma with a zero rb_subtree_gap value
 560         * (to be consistent with what we did on the way down), and then
 561         * immediately update the gap to the correct value. Finally we
 562         * rebalance the rbtree after all augmented values have been set.
 563         */
 564        rb_link_node(&vma->vm_rb, rb_parent, rb_link);
 565        vma->rb_subtree_gap = 0;
 566        vma_gap_update(vma);
 567        vma_rb_insert(vma, &mm->mm_rb);
 568}
 569
 570static void __vma_link_file(struct vm_area_struct *vma)
 571{
 572        struct file *file;
 573
 574        file = vma->vm_file;
 575        if (file) {
 576                struct address_space *mapping = file->f_mapping;
 577
 578                if (vma->vm_flags & VM_DENYWRITE)
 579                        atomic_dec(&file_inode(file)->i_writecount);
 580                if (vma->vm_flags & VM_SHARED)
 581                        mapping->i_mmap_writable++;
 582
 583                flush_dcache_mmap_lock(mapping);
 584                if (unlikely(vma->vm_flags & VM_NONLINEAR))
 585                        vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
 586                else
 587                        vma_interval_tree_insert(vma, &mapping->i_mmap);
 588                flush_dcache_mmap_unlock(mapping);
 589        }
 590}
 591
 592static void
 593__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 594        struct vm_area_struct *prev, struct rb_node **rb_link,
 595        struct rb_node *rb_parent)
 596{
 597        __vma_link_list(mm, vma, prev, rb_parent);
 598        __vma_link_rb(mm, vma, rb_link, rb_parent);
 599}
 600
 601static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 602                        struct vm_area_struct *prev, struct rb_node **rb_link,
 603                        struct rb_node *rb_parent)
 604{
 605        struct address_space *mapping = NULL;
 606
 607        if (vma->vm_file)
 608                mapping = vma->vm_file->f_mapping;
 609
 610        if (mapping)
 611                mutex_lock(&mapping->i_mmap_mutex);
 612
 613        __vma_link(mm, vma, prev, rb_link, rb_parent);
 614        __vma_link_file(vma);
 615
 616        if (mapping)
 617                mutex_unlock(&mapping->i_mmap_mutex);
 618
 619        mm->map_count++;
 620        validate_mm(mm);
 621}
 622
 623/*
 624 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
 625 * mm's list and rbtree.  It has already been inserted into the interval tree.
 626 */
 627static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 628{
 629        struct vm_area_struct *prev;
 630        struct rb_node **rb_link, *rb_parent;
 631
 632        if (find_vma_links(mm, vma->vm_start, vma->vm_end,
 633                           &prev, &rb_link, &rb_parent))
 634                BUG();
 635        __vma_link(mm, vma, prev, rb_link, rb_parent);
 636        mm->map_count++;
 637}
 638
 639static inline void
 640__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
 641                struct vm_area_struct *prev)
 642{
 643        struct vm_area_struct *next;
 644
 645        vma_rb_erase(vma, &mm->mm_rb);
 646        prev->vm_next = next = vma->vm_next;
 647        if (next)
 648                next->vm_prev = prev;
 649        if (mm->mmap_cache == vma)
 650                mm->mmap_cache = prev;
 651}
 652
 653/*
 654 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 655 * is already present in an i_mmap tree without adjusting the tree.
 656 * The following helper function should be used when such adjustments
 657 * are necessary.  The "insert" vma (if any) is to be inserted
 658 * before we drop the necessary locks.
 659 */
 660int vma_adjust(struct vm_area_struct *vma, unsigned long start,
 661        unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
 662{
 663        struct mm_struct *mm = vma->vm_mm;
 664        struct vm_area_struct *next = vma->vm_next;
 665        struct vm_area_struct *importer = NULL;
 666        struct address_space *mapping = NULL;
 667        struct rb_root *root = NULL;
 668        struct anon_vma *anon_vma = NULL;
 669        struct file *file = vma->vm_file;
 670        bool start_changed = false, end_changed = false;
 671        long adjust_next = 0;
 672        int remove_next = 0;
 673
 674        if (next && !insert) {
 675                struct vm_area_struct *exporter = NULL;
 676
 677                if (end >= next->vm_end) {
 678                        /*
 679                         * vma expands, overlapping all the next, and
 680                         * perhaps the one after too (mprotect case 6).
 681                         */
 682again:                  remove_next = 1 + (end > next->vm_end);
 683                        end = next->vm_end;
 684                        exporter = next;
 685                        importer = vma;
 686                } else if (end > next->vm_start) {
 687                        /*
 688                         * vma expands, overlapping part of the next:
 689                         * mprotect case 5 shifting the boundary up.
 690                         */
 691                        adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
 692                        exporter = next;
 693                        importer = vma;
 694                } else if (end < vma->vm_end) {
 695                        /*
 696                         * vma shrinks, and !insert tells it's not
 697                         * split_vma inserting another: so it must be
 698                         * mprotect case 4 shifting the boundary down.
 699                         */
 700                        adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
 701                        exporter = vma;
 702                        importer = next;
 703                }
 704
 705                /*
 706                 * Easily overlooked: when mprotect shifts the boundary,
 707                 * make sure the expanding vma has anon_vma set if the
 708                 * shrinking vma had, to cover any anon pages imported.
 709                 */
 710                if (exporter && exporter->anon_vma && !importer->anon_vma) {
 711                        if (anon_vma_clone(importer, exporter))
 712                                return -ENOMEM;
 713                        importer->anon_vma = exporter->anon_vma;
 714                }
 715        }
 716
 717        if (file) {
 718                mapping = file->f_mapping;
 719                if (!(vma->vm_flags & VM_NONLINEAR)) {
 720                        root = &mapping->i_mmap;
 721                        uprobe_munmap(vma, vma->vm_start, vma->vm_end);
 722
 723                        if (adjust_next)
 724                                uprobe_munmap(next, next->vm_start,
 725                                                        next->vm_end);
 726                }
 727
 728                mutex_lock(&mapping->i_mmap_mutex);
 729                if (insert) {
 730                        /*
 731                         * Put into interval tree now, so instantiated pages
 732                         * are visible to arm/parisc __flush_dcache_page
 733                         * throughout; but we cannot insert into address
 734                         * space until vma start or end is updated.
 735                         */
 736                        __vma_link_file(insert);
 737                }
 738        }
 739
 740        vma_adjust_trans_huge(vma, start, end, adjust_next);
 741
 742        anon_vma = vma->anon_vma;
 743        if (!anon_vma && adjust_next)
 744                anon_vma = next->anon_vma;
 745        if (anon_vma) {
 746                VM_BUG_ON(adjust_next && next->anon_vma &&
 747                          anon_vma != next->anon_vma);
 748                anon_vma_lock_write(anon_vma);
 749                anon_vma_interval_tree_pre_update_vma(vma);
 750                if (adjust_next)
 751                        anon_vma_interval_tree_pre_update_vma(next);
 752        }
 753
 754        if (root) {
 755                flush_dcache_mmap_lock(mapping);
 756                vma_interval_tree_remove(vma, root);
 757                if (adjust_next)
 758                        vma_interval_tree_remove(next, root);
 759        }
 760
 761        if (start != vma->vm_start) {
 762                vma->vm_start = start;
 763                start_changed = true;
 764        }
 765        if (end != vma->vm_end) {
 766                vma->vm_end = end;
 767                end_changed = true;
 768        }
 769        vma->vm_pgoff = pgoff;
 770        if (adjust_next) {
 771                next->vm_start += adjust_next << PAGE_SHIFT;
 772                next->vm_pgoff += adjust_next;
 773        }
 774
 775        if (root) {
 776                if (adjust_next)
 777                        vma_interval_tree_insert(next, root);
 778                vma_interval_tree_insert(vma, root);
 779                flush_dcache_mmap_unlock(mapping);
 780        }
 781
 782        if (remove_next) {
 783                /*
 784                 * vma_merge has merged next into vma, and needs
 785                 * us to remove next before dropping the locks.
 786                 */
 787                __vma_unlink(mm, next, vma);
 788                if (file)
 789                        __remove_shared_vm_struct(next, file, mapping);
 790        } else if (insert) {
 791                /*
 792                 * split_vma has split insert from vma, and needs
 793                 * us to insert it before dropping the locks
 794                 * (it may either follow vma or precede it).
 795                 */
 796                __insert_vm_struct(mm, insert);
 797        } else {
 798                if (start_changed)
 799                        vma_gap_update(vma);
 800                if (end_changed) {
 801                        if (!next)
 802                                mm->highest_vm_end = end;
 803                        else if (!adjust_next)
 804                                vma_gap_update(next);
 805                }
 806        }
 807
 808        if (anon_vma) {
 809                anon_vma_interval_tree_post_update_vma(vma);
 810                if (adjust_next)
 811                        anon_vma_interval_tree_post_update_vma(next);
 812                anon_vma_unlock_write(anon_vma);
 813        }
 814        if (mapping)
 815                mutex_unlock(&mapping->i_mmap_mutex);
 816
 817        if (root) {
 818                uprobe_mmap(vma);
 819
 820                if (adjust_next)
 821                        uprobe_mmap(next);
 822        }
 823
 824        if (remove_next) {
 825                if (file) {
 826                        uprobe_munmap(next, next->vm_start, next->vm_end);
 827                        fput(file);
 828                }
 829                if (next->anon_vma)
 830                        anon_vma_merge(vma, next);
 831                mm->map_count--;
 832                mpol_put(vma_policy(next));
 833                kmem_cache_free(vm_area_cachep, next);
 834                /*
 835                 * In mprotect's case 6 (see comments on vma_merge),
 836                 * we must remove another next too. It would clutter
 837                 * up the code too much to do both in one go.
 838                 */
 839                next = vma->vm_next;
 840                if (remove_next == 2)
 841                        goto again;
 842                else if (next)
 843                        vma_gap_update(next);
 844                else
 845                        mm->highest_vm_end = end;
 846        }
 847        if (insert && file)
 848                uprobe_mmap(insert);
 849
 850        validate_mm(mm);
 851
 852        return 0;
 853}
 854
 855/*
 856 * If the vma has a ->close operation then the driver probably needs to release
 857 * per-vma resources, so we don't attempt to merge those.
 858 */
 859static inline int is_mergeable_vma(struct vm_area_struct *vma,
 860                        struct file *file, unsigned long vm_flags)
 861{
 862        if (vma->vm_flags ^ vm_flags)
 863                return 0;
 864        if (vma->vm_file != file)
 865                return 0;
 866        if (vma->vm_ops && vma->vm_ops->close)
 867                return 0;
 868        return 1;
 869}
 870
 871static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
 872                                        struct anon_vma *anon_vma2,
 873                                        struct vm_area_struct *vma)
 874{
 875        /*
 876         * The list_is_singular() test is to avoid merging VMA cloned from
 877         * parents. This can improve scalability caused by anon_vma lock.
 878         */
 879        if ((!anon_vma1 || !anon_vma2) && (!vma ||
 880                list_is_singular(&vma->anon_vma_chain)))
 881                return 1;
 882        return anon_vma1 == anon_vma2;
 883}
 884
 885/*
 886 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 887 * in front of (at a lower virtual address and file offset than) the vma.
 888 *
 889 * We cannot merge two vmas if they have differently assigned (non-NULL)
 890 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 891 *
 892 * We don't check here for the merged mmap wrapping around the end of pagecache
 893 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 894 * wrap, nor mmaps which cover the final page at index -1UL.
 895 */
 896static int
 897can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
 898        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 899{
 900        if (is_mergeable_vma(vma, file, vm_flags) &&
 901            is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 902                if (vma->vm_pgoff == vm_pgoff)
 903                        return 1;
 904        }
 905        return 0;
 906}
 907
 908/*
 909 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 910 * beyond (at a higher virtual address and file offset than) the vma.
 911 *
 912 * We cannot merge two vmas if they have differently assigned (non-NULL)
 913 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 914 */
 915static int
 916can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 917        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 918{
 919        if (is_mergeable_vma(vma, file, vm_flags) &&
 920            is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 921                pgoff_t vm_pglen;
 922                vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 923                if (vma->vm_pgoff + vm_pglen == vm_pgoff)
 924                        return 1;
 925        }
 926        return 0;
 927}
 928
 929/*
 930 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
 931 * whether that can be merged with its predecessor or its successor.
 932 * Or both (it neatly fills a hole).
 933 *
 934 * In most cases - when called for mmap, brk or mremap - [addr,end) is
 935 * certain not to be mapped by the time vma_merge is called; but when
 936 * called for mprotect, it is certain to be already mapped (either at
 937 * an offset within prev, or at the start of next), and the flags of
 938 * this area are about to be changed to vm_flags - and the no-change
 939 * case has already been eliminated.
 940 *
 941 * The following mprotect cases have to be considered, where AAAA is
 942 * the area passed down from mprotect_fixup, never extending beyond one
 943 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
 944 *
 945 *     AAAA             AAAA                AAAA          AAAA
 946 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
 947 *    cannot merge    might become    might become    might become
 948 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
 949 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
 950 *    mremap move:                                    PPPPNNNNNNNN 8
 951 *        AAAA
 952 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
 953 *    might become    case 1 below    case 2 below    case 3 below
 954 *
 955 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
 956 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
 957 */
 958struct vm_area_struct *vma_merge(struct mm_struct *mm,
 959                        struct vm_area_struct *prev, unsigned long addr,
 960                        unsigned long end, unsigned long vm_flags,
 961                        struct anon_vma *anon_vma, struct file *file,
 962                        pgoff_t pgoff, struct mempolicy *policy)
 963{
 964        pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
 965        struct vm_area_struct *area, *next;
 966        int err;
 967
 968        /*
 969         * We later require that vma->vm_flags == vm_flags,
 970         * so this tests vma->vm_flags & VM_SPECIAL, too.
 971         */
 972        if (vm_flags & VM_SPECIAL)
 973                return NULL;
 974
 975        if (prev)
 976                next = prev->vm_next;
 977        else
 978                next = mm->mmap;
 979        area = next;
 980        if (next && next->vm_end == end)                /* cases 6, 7, 8 */
 981                next = next->vm_next;
 982
 983        /*
 984         * Can it merge with the predecessor?
 985         */
 986        if (prev && prev->vm_end == addr &&
 987                        mpol_equal(vma_policy(prev), policy) &&
 988                        can_vma_merge_after(prev, vm_flags,
 989                                                anon_vma, file, pgoff)) {
 990                /*
 991                 * OK, it can.  Can we now merge in the successor as well?
 992                 */
 993                if (next && end == next->vm_start &&
 994                                mpol_equal(policy, vma_policy(next)) &&
 995                                can_vma_merge_before(next, vm_flags,
 996                                        anon_vma, file, pgoff+pglen) &&
 997                                is_mergeable_anon_vma(prev->anon_vma,
 998                                                      next->anon_vma, NULL)) {
 999                                                        /* cases 1, 6 */
1000                        err = vma_adjust(prev, prev->vm_start,
1001                                next->vm_end, prev->vm_pgoff, NULL);
1002                } else                                  /* cases 2, 5, 7 */
1003                        err = vma_adjust(prev, prev->vm_start,
1004                                end, prev->vm_pgoff, NULL);
1005                if (err)
1006                        return NULL;
1007                khugepaged_enter_vma_merge(prev);
1008                return prev;
1009        }
1010
1011        /*
1012         * Can this new request be merged in front of next?
1013         */
1014        if (next && end == next->vm_start &&
1015                        mpol_equal(policy, vma_policy(next)) &&
1016                        can_vma_merge_before(next, vm_flags,
1017                                        anon_vma, file, pgoff+pglen)) {
1018                if (prev && addr < prev->vm_end)        /* case 4 */
1019                        err = vma_adjust(prev, prev->vm_start,
1020                                addr, prev->vm_pgoff, NULL);
1021                else                                    /* cases 3, 8 */
1022                        err = vma_adjust(area, addr, next->vm_end,
1023                                next->vm_pgoff - pglen, NULL);
1024                if (err)
1025                        return NULL;
1026                khugepaged_enter_vma_merge(area);
1027                return area;
1028        }
1029
1030        return NULL;
1031}
1032
1033/*
1034 * Rough compatbility check to quickly see if it's even worth looking
1035 * at sharing an anon_vma.
1036 *
1037 * They need to have the same vm_file, and the flags can only differ
1038 * in things that mprotect may change.
1039 *
1040 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1041 * we can merge the two vma's. For example, we refuse to merge a vma if
1042 * there is a vm_ops->close() function, because that indicates that the
1043 * driver is doing some kind of reference counting. But that doesn't
1044 * really matter for the anon_vma sharing case.
1045 */
1046static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1047{
1048        return a->vm_end == b->vm_start &&
1049                mpol_equal(vma_policy(a), vma_policy(b)) &&
1050                a->vm_file == b->vm_file &&
1051                !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
1052                b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1053}
1054
1055/*
1056 * Do some basic sanity checking to see if we can re-use the anon_vma
1057 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1058 * the same as 'old', the other will be the new one that is trying
1059 * to share the anon_vma.
1060 *
1061 * NOTE! This runs with mm_sem held for reading, so it is possible that
1062 * the anon_vma of 'old' is concurrently in the process of being set up
1063 * by another page fault trying to merge _that_. But that's ok: if it
1064 * is being set up, that automatically means that it will be a singleton
1065 * acceptable for merging, so we can do all of this optimistically. But
1066 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
1067 *
1068 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1069 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1070 * is to return an anon_vma that is "complex" due to having gone through
1071 * a fork).
1072 *
1073 * We also make sure that the two vma's are compatible (adjacent,
1074 * and with the same memory policies). That's all stable, even with just
1075 * a read lock on the mm_sem.
1076 */
1077static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1078{
1079        if (anon_vma_compatible(a, b)) {
1080                struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
1081
1082                if (anon_vma && list_is_singular(&old->anon_vma_chain))
1083                        return anon_vma;
1084        }
1085        return NULL;
1086}
1087
1088/*
1089 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1090 * neighbouring vmas for a suitable anon_vma, before it goes off
1091 * to allocate a new anon_vma.  It checks because a repetitive
1092 * sequence of mprotects and faults may otherwise lead to distinct
1093 * anon_vmas being allocated, preventing vma merge in subsequent
1094 * mprotect.
1095 */
1096struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1097{
1098        struct anon_vma *anon_vma;
1099        struct vm_area_struct *near;
1100
1101        near = vma->vm_next;
1102        if (!near)
1103                goto try_prev;
1104
1105        anon_vma = reusable_anon_vma(near, vma, near);
1106        if (anon_vma)
1107                return anon_vma;
1108try_prev:
1109        near = vma->vm_prev;
1110        if (!near)
1111                goto none;
1112
1113        anon_vma = reusable_anon_vma(near, near, vma);
1114        if (anon_vma)
1115                return anon_vma;
1116none:
1117        /*
1118         * There's no absolute need to look only at touching neighbours:
1119         * we could search further afield for "compatible" anon_vmas.
1120         * But it would probably just be a waste of time searching,
1121         * or lead to too many vmas hanging off the same anon_vma.
1122         * We're trying to allow mprotect remerging later on,
1123         * not trying to minimize memory used for anon_vmas.
1124         */
1125        return NULL;
1126}
1127
1128#ifdef CONFIG_PROC_FS
1129void vm_stat_account(struct mm_struct *mm, unsigned long flags,
1130                                                struct file *file, long pages)
1131{
1132        const unsigned long stack_flags
1133                = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
1134
1135        mm->total_vm += pages;
1136
1137        if (file) {
1138                mm->shared_vm += pages;
1139                if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
1140                        mm->exec_vm += pages;
1141        } else if (flags & stack_flags)
1142                mm->stack_vm += pages;
1143}
1144#endif /* CONFIG_PROC_FS */
1145
1146/*
1147 * If a hint addr is less than mmap_min_addr change hint to be as
1148 * low as possible but still greater than mmap_min_addr
1149 */
1150static inline unsigned long round_hint_to_min(unsigned long hint)
1151{
1152        hint &= PAGE_MASK;
1153        if (((void *)hint != NULL) &&
1154            (hint < mmap_min_addr))
1155                return PAGE_ALIGN(mmap_min_addr);
1156        return hint;
1157}
1158
1159/*
1160 * The caller must hold down_write(&current->mm->mmap_sem).
1161 */
1162
1163unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
1164                        unsigned long len, unsigned long prot,
1165                        unsigned long flags, unsigned long pgoff,
1166                        unsigned long *populate)
1167{
1168        struct mm_struct * mm = current->mm;
1169        struct inode *inode;
1170        vm_flags_t vm_flags;
1171
1172        *populate = 0;
1173
1174        /*
1175         * Does the application expect PROT_READ to imply PROT_EXEC?
1176         *
1177         * (the exception is when the underlying filesystem is noexec
1178         *  mounted, in which case we dont add PROT_EXEC.)
1179         */
1180        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1181                if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
1182                        prot |= PROT_EXEC;
1183
1184        if (!len)
1185                return -EINVAL;
1186
1187        if (!(flags & MAP_FIXED))
1188                addr = round_hint_to_min(addr);
1189
1190        /* Careful about overflows.. */
1191        len = PAGE_ALIGN(len);
1192        if (!len)
1193                return -ENOMEM;
1194
1195        /* offset overflow? */
1196        if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1197               return -EOVERFLOW;
1198
1199        /* Too many mappings? */
1200        if (mm->map_count > sysctl_max_map_count)
1201                return -ENOMEM;
1202
1203        /* Obtain the address to map to. we verify (or select) it and ensure
1204         * that it represents a valid section of the address space.
1205         */
1206        addr = get_unmapped_area(file, addr, len, pgoff, flags);
1207        if (addr & ~PAGE_MASK)
1208                return addr;
1209
1210        /* Do simple checking here so the lower-level routines won't have
1211         * to. we assume access permissions have been handled by the open
1212         * of the memory object, so we don't do any here.
1213         */
1214        vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1215                        mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1216
1217        if (flags & MAP_LOCKED)
1218                if (!can_do_mlock())
1219                        return -EPERM;
1220
1221        /* mlock MCL_FUTURE? */
1222        if (vm_flags & VM_LOCKED) {
1223                unsigned long locked, lock_limit;
1224                locked = len >> PAGE_SHIFT;
1225                locked += mm->locked_vm;
1226                lock_limit = rlimit(RLIMIT_MEMLOCK);
1227                lock_limit >>= PAGE_SHIFT;
1228                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1229                        return -EAGAIN;
1230        }
1231
1232        inode = file ? file_inode(file) : NULL;
1233
1234        if (file) {
1235                switch (flags & MAP_TYPE) {
1236                case MAP_SHARED:
1237                        if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1238                                return -EACCES;
1239
1240                        /*
1241                         * Make sure we don't allow writing to an append-only
1242                         * file..
1243                         */
1244                        if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1245                                return -EACCES;
1246
1247                        /*
1248                         * Make sure there are no mandatory locks on the file.
1249                         */
1250                        if (locks_verify_locked(inode))
1251                                return -EAGAIN;
1252
1253                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1254                        if (!(file->f_mode & FMODE_WRITE))
1255                                vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1256
1257                        /* fall through */
1258                case MAP_PRIVATE:
1259                        if (!(file->f_mode & FMODE_READ))
1260                                return -EACCES;
1261                        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1262                                if (vm_flags & VM_EXEC)
1263                                        return -EPERM;
1264                                vm_flags &= ~VM_MAYEXEC;
1265                        }
1266
1267                        if (!file->f_op || !file->f_op->mmap)
1268                                return -ENODEV;
1269                        break;
1270
1271                default:
1272                        return -EINVAL;
1273                }
1274        } else {
1275                switch (flags & MAP_TYPE) {
1276                case MAP_SHARED:
1277                        /*
1278                         * Ignore pgoff.
1279                         */
1280                        pgoff = 0;
1281                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1282                        break;
1283                case MAP_PRIVATE:
1284                        /*
1285                         * Set pgoff according to addr for anon_vma.
1286                         */
1287                        pgoff = addr >> PAGE_SHIFT;
1288                        break;
1289                default:
1290                        return -EINVAL;
1291                }
1292        }
1293
1294        /*
1295         * Set 'VM_NORESERVE' if we should not account for the
1296         * memory use of this mapping.
1297         */
1298        if (flags & MAP_NORESERVE) {
1299                /* We honor MAP_NORESERVE if allowed to overcommit */
1300                if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1301                        vm_flags |= VM_NORESERVE;
1302
1303                /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1304                if (file && is_file_hugepages(file))
1305                        vm_flags |= VM_NORESERVE;
1306        }
1307
1308        addr = mmap_region(file, addr, len, vm_flags, pgoff);
1309        if (!IS_ERR_VALUE(addr) &&
1310            ((vm_flags & VM_LOCKED) ||
1311             (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1312                *populate = len;
1313        return addr;
1314}
1315
1316SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1317                unsigned long, prot, unsigned long, flags,
1318                unsigned long, fd, unsigned long, pgoff)
1319{
1320        struct file *file = NULL;
1321        unsigned long retval = -EBADF;
1322
1323        if (!(flags & MAP_ANONYMOUS)) {
1324                audit_mmap_fd(fd, flags);
1325                if (unlikely(flags & MAP_HUGETLB))
1326                        return -EINVAL;
1327                file = fget(fd);
1328                if (!file)
1329                        goto out;
1330        } else if (flags & MAP_HUGETLB) {
1331                struct user_struct *user = NULL;
1332                /*
1333                 * VM_NORESERVE is used because the reservations will be
1334                 * taken when vm_ops->mmap() is called
1335                 * A dummy user value is used because we are not locking
1336                 * memory so no accounting is necessary
1337                 */
1338                file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len,
1339                                VM_NORESERVE,
1340                                &user, HUGETLB_ANONHUGE_INODE,
1341                                (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1342                if (IS_ERR(file))
1343                        return PTR_ERR(file);
1344        }
1345
1346        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1347
1348        retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1349        if (file)
1350                fput(file);
1351out:
1352        return retval;
1353}
1354
1355#ifdef __ARCH_WANT_SYS_OLD_MMAP
1356struct mmap_arg_struct {
1357        unsigned long addr;
1358        unsigned long len;
1359        unsigned long prot;
1360        unsigned long flags;
1361        unsigned long fd;
1362        unsigned long offset;
1363};
1364
1365SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1366{
1367        struct mmap_arg_struct a;
1368
1369        if (copy_from_user(&a, arg, sizeof(a)))
1370                return -EFAULT;
1371        if (a.offset & ~PAGE_MASK)
1372                return -EINVAL;
1373
1374        return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1375                              a.offset >> PAGE_SHIFT);
1376}
1377#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1378
1379/*
1380 * Some shared mappigns will want the pages marked read-only
1381 * to track write events. If so, we'll downgrade vm_page_prot
1382 * to the private version (using protection_map[] without the
1383 * VM_SHARED bit).
1384 */
1385int vma_wants_writenotify(struct vm_area_struct *vma)
1386{
1387        vm_flags_t vm_flags = vma->vm_flags;
1388
1389        /* If it was private or non-writable, the write bit is already clear */
1390        if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1391                return 0;
1392
1393        /* The backer wishes to know when pages are first written to? */
1394        if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1395                return 1;
1396
1397        /* The open routine did something to the protections already? */
1398        if (pgprot_val(vma->vm_page_prot) !=
1399            pgprot_val(vm_get_page_prot(vm_flags)))
1400                return 0;
1401
1402        /* Specialty mapping? */
1403        if (vm_flags & VM_PFNMAP)
1404                return 0;
1405
1406        /* Can the mapping track the dirty pages? */
1407        return vma->vm_file && vma->vm_file->f_mapping &&
1408                mapping_cap_account_dirty(vma->vm_file->f_mapping);
1409}
1410
1411/*
1412 * We account for memory if it's a private writeable mapping,
1413 * not hugepages and VM_NORESERVE wasn't set.
1414 */
1415static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1416{
1417        /*
1418         * hugetlb has its own accounting separate from the core VM
1419         * VM_HUGETLB may not be set yet so we cannot check for that flag.
1420         */
1421        if (file && is_file_hugepages(file))
1422                return 0;
1423
1424        return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1425}
1426
1427unsigned long mmap_region(struct file *file, unsigned long addr,
1428                unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1429{
1430        struct mm_struct *mm = current->mm;
1431        struct vm_area_struct *vma, *prev;
1432        int correct_wcount = 0;
1433        int error;
1434        struct rb_node **rb_link, *rb_parent;
1435        unsigned long charged = 0;
1436        struct inode *inode =  file ? file_inode(file) : NULL;
1437
1438        /* Clear old maps */
1439        error = -ENOMEM;
1440munmap_back:
1441        if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
1442                if (do_munmap(mm, addr, len))
1443                        return -ENOMEM;
1444                goto munmap_back;
1445        }
1446
1447        /* Check against address space limit. */
1448        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1449                return -ENOMEM;
1450
1451        /*
1452         * Private writable mapping: check memory availability
1453         */
1454        if (accountable_mapping(file, vm_flags)) {
1455                charged = len >> PAGE_SHIFT;
1456                if (security_vm_enough_memory_mm(mm, charged))
1457                        return -ENOMEM;
1458                vm_flags |= VM_ACCOUNT;
1459        }
1460
1461        /*
1462         * Can we just expand an old mapping?
1463         */
1464        vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1465        if (vma)
1466                goto out;
1467
1468        /*
1469         * Determine the object being mapped and call the appropriate
1470         * specific mapper. the address has already been validated, but
1471         * not unmapped, but the maps are removed from the list.
1472         */
1473        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1474        if (!vma) {
1475                error = -ENOMEM;
1476                goto unacct_error;
1477        }
1478
1479        vma->vm_mm = mm;
1480        vma->vm_start = addr;
1481        vma->vm_end = addr + len;
1482        vma->vm_flags = vm_flags;
1483        vma->vm_page_prot = vm_get_page_prot(vm_flags);
1484        vma->vm_pgoff = pgoff;
1485        INIT_LIST_HEAD(&vma->anon_vma_chain);
1486
1487        error = -EINVAL;        /* when rejecting VM_GROWSDOWN|VM_GROWSUP */
1488
1489        if (file) {
1490                if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1491                        goto free_vma;
1492                if (vm_flags & VM_DENYWRITE) {
1493                        error = deny_write_access(file);
1494                        if (error)
1495                                goto free_vma;
1496                        correct_wcount = 1;
1497                }
1498                vma->vm_file = get_file(file);
1499                error = file->f_op->mmap(file, vma);
1500                if (error)
1501                        goto unmap_and_free_vma;
1502
1503                /* Can addr have changed??
1504                 *
1505                 * Answer: Yes, several device drivers can do it in their
1506                 *         f_op->mmap method. -DaveM
1507                 * Bug: If addr is changed, prev, rb_link, rb_parent should
1508                 *      be updated for vma_link()
1509                 */
1510                WARN_ON_ONCE(addr != vma->vm_start);
1511
1512                addr = vma->vm_start;
1513                pgoff = vma->vm_pgoff;
1514                vm_flags = vma->vm_flags;
1515        } else if (vm_flags & VM_SHARED) {
1516                if (unlikely(vm_flags & (VM_GROWSDOWN|VM_GROWSUP)))
1517                        goto free_vma;
1518                error = shmem_zero_setup(vma);
1519                if (error)
1520                        goto free_vma;
1521        }
1522
1523        if (vma_wants_writenotify(vma)) {
1524                pgprot_t pprot = vma->vm_page_prot;
1525
1526                /* Can vma->vm_page_prot have changed??
1527                 *
1528                 * Answer: Yes, drivers may have changed it in their
1529                 *         f_op->mmap method.
1530                 *
1531                 * Ensures that vmas marked as uncached stay that way.
1532                 */
1533                vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1534                if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1535                        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1536        }
1537
1538        vma_link(mm, vma, prev, rb_link, rb_parent);
1539        file = vma->vm_file;
1540
1541        /* Once vma denies write, undo our temporary denial count */
1542        if (correct_wcount)
1543                atomic_inc(&inode->i_writecount);
1544out:
1545        perf_event_mmap(vma);
1546
1547        vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1548        if (vm_flags & VM_LOCKED) {
1549                if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1550                                        vma == get_gate_vma(current->mm)))
1551                        mm->locked_vm += (len >> PAGE_SHIFT);
1552                else
1553                        vma->vm_flags &= ~VM_LOCKED;
1554        }
1555
1556        if (file)
1557                uprobe_mmap(vma);
1558
1559        return addr;
1560
1561unmap_and_free_vma:
1562        if (correct_wcount)
1563                atomic_inc(&inode->i_writecount);
1564        vma->vm_file = NULL;
1565        fput(file);
1566
1567        /* Undo any partial mapping done by a device driver. */
1568        unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1569        charged = 0;
1570free_vma:
1571        kmem_cache_free(vm_area_cachep, vma);
1572unacct_error:
1573        if (charged)
1574                vm_unacct_memory(charged);
1575        return error;
1576}
1577
1578unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1579{
1580        /*
1581         * We implement the search by looking for an rbtree node that
1582         * immediately follows a suitable gap. That is,
1583         * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1584         * - gap_end   = vma->vm_start        >= info->low_limit  + length;
1585         * - gap_end - gap_start >= length
1586         */
1587
1588        struct mm_struct *mm = current->mm;
1589        struct vm_area_struct *vma;
1590        unsigned long length, low_limit, high_limit, gap_start, gap_end;
1591
1592        /* Adjust search length to account for worst case alignment overhead */
1593        length = info->length + info->align_mask;
1594        if (length < info->length)
1595                return -ENOMEM;
1596
1597        /* Adjust search limits by the desired length */
1598        if (info->high_limit < length)
1599                return -ENOMEM;
1600        high_limit = info->high_limit - length;
1601
1602        if (info->low_limit > high_limit)
1603                return -ENOMEM;
1604        low_limit = info->low_limit + length;
1605
1606        /* Check if rbtree root looks promising */
1607        if (RB_EMPTY_ROOT(&mm->mm_rb))
1608                goto check_highest;
1609        vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1610        if (vma->rb_subtree_gap < length)
1611                goto check_highest;
1612
1613        while (true) {
1614                /* Visit left subtree if it looks promising */
1615                gap_end = vma->vm_start;
1616                if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1617                        struct vm_area_struct *left =
1618                                rb_entry(vma->vm_rb.rb_left,
1619                                         struct vm_area_struct, vm_rb);
1620                        if (left->rb_subtree_gap >= length) {
1621                                vma = left;
1622                                continue;
1623                        }
1624                }
1625
1626                gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1627check_current:
1628                /* Check if current node has a suitable gap */
1629                if (gap_start > high_limit)
1630                        return -ENOMEM;
1631                if (gap_end >= low_limit && gap_end - gap_start >= length)
1632                        goto found;
1633
1634                /* Visit right subtree if it looks promising */
1635                if (vma->vm_rb.rb_right) {
1636                        struct vm_area_struct *right =
1637                                rb_entry(vma->vm_rb.rb_right,
1638                                         struct vm_area_struct, vm_rb);
1639                        if (right->rb_subtree_gap >= length) {
1640                                vma = right;
1641                                continue;
1642                        }
1643                }
1644
1645                /* Go back up the rbtree to find next candidate node */
1646                while (true) {
1647                        struct rb_node *prev = &vma->vm_rb;
1648                        if (!rb_parent(prev))
1649                                goto check_highest;
1650                        vma = rb_entry(rb_parent(prev),
1651                                       struct vm_area_struct, vm_rb);
1652                        if (prev == vma->vm_rb.rb_left) {
1653                                gap_start = vma->vm_prev->vm_end;
1654                                gap_end = vma->vm_start;
1655                                goto check_current;
1656                        }
1657                }
1658        }
1659
1660check_highest:
1661        /* Check highest gap, which does not precede any rbtree node */
1662        gap_start = mm->highest_vm_end;
1663        gap_end = ULONG_MAX;  /* Only for VM_BUG_ON below */
1664        if (gap_start > high_limit)
1665                return -ENOMEM;
1666
1667found:
1668        /* We found a suitable gap. Clip it with the original low_limit. */
1669        if (gap_start < info->low_limit)
1670                gap_start = info->low_limit;
1671
1672        /* Adjust gap address to the desired alignment */
1673        gap_start += (info->align_offset - gap_start) & info->align_mask;
1674
1675        VM_BUG_ON(gap_start + info->length > info->high_limit);
1676        VM_BUG_ON(gap_start + info->length > gap_end);
1677        return gap_start;
1678}
1679
1680unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1681{
1682        struct mm_struct *mm = current->mm;
1683        struct vm_area_struct *vma;
1684        unsigned long length, low_limit, high_limit, gap_start, gap_end;
1685
1686        /* Adjust search length to account for worst case alignment overhead */
1687        length = info->length + info->align_mask;
1688        if (length < info->length)
1689                return -ENOMEM;
1690
1691        /*
1692         * Adjust search limits by the desired length.
1693         * See implementation comment at top of unmapped_area().
1694         */
1695        gap_end = info->high_limit;
1696        if (gap_end < length)
1697                return -ENOMEM;
1698        high_limit = gap_end - length;
1699
1700        if (info->low_limit > high_limit)
1701                return -ENOMEM;
1702        low_limit = info->low_limit + length;
1703
1704        /* Check highest gap, which does not precede any rbtree node */
1705        gap_start = mm->highest_vm_end;
1706        if (gap_start <= high_limit)
1707                goto found_highest;
1708
1709        /* Check if rbtree root looks promising */
1710        if (RB_EMPTY_ROOT(&mm->mm_rb))
1711                return -ENOMEM;
1712        vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1713        if (vma->rb_subtree_gap < length)
1714                return -ENOMEM;
1715
1716        while (true) {
1717                /* Visit right subtree if it looks promising */
1718                gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1719                if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1720                        struct vm_area_struct *right =
1721                                rb_entry(vma->vm_rb.rb_right,
1722                                         struct vm_area_struct, vm_rb);
1723                        if (right->rb_subtree_gap >= length) {
1724                                vma = right;
1725                                continue;
1726                        }
1727                }
1728
1729check_current:
1730                /* Check if current node has a suitable gap */
1731                gap_end = vma->vm_start;
1732                if (gap_end < low_limit)
1733                        return -ENOMEM;
1734                if (gap_start <= high_limit && gap_end - gap_start >= length)
1735                        goto found;
1736
1737                /* Visit left subtree if it looks promising */
1738                if (vma->vm_rb.rb_left) {
1739                        struct vm_area_struct *left =
1740                                rb_entry(vma->vm_rb.rb_left,
1741                                         struct vm_area_struct, vm_rb);
1742                        if (left->rb_subtree_gap >= length) {
1743                                vma = left;
1744                                continue;
1745                        }
1746                }
1747
1748                /* Go back up the rbtree to find next candidate node */
1749                while (true) {
1750                        struct rb_node *prev = &vma->vm_rb;
1751                        if (!rb_parent(prev))
1752                                return -ENOMEM;
1753                        vma = rb_entry(rb_parent(prev),
1754                                       struct vm_area_struct, vm_rb);
1755                        if (prev == vma->vm_rb.rb_right) {
1756                                gap_start = vma->vm_prev ?
1757                                        vma->vm_prev->vm_end : 0;
1758                                goto check_current;
1759                        }
1760                }
1761        }
1762
1763found:
1764        /* We found a suitable gap. Clip it with the original high_limit. */
1765        if (gap_end > info->high_limit)
1766                gap_end = info->high_limit;
1767
1768found_highest:
1769        /* Compute highest gap address at the desired alignment */
1770        gap_end -= info->length;
1771        gap_end -= (gap_end - info->align_offset) & info->align_mask;
1772
1773        VM_BUG_ON(gap_end < info->low_limit);
1774        VM_BUG_ON(gap_end < gap_start);
1775        return gap_end;
1776}
1777
1778/* Get an address range which is currently unmapped.
1779 * For shmat() with addr=0.
1780 *
1781 * Ugly calling convention alert:
1782 * Return value with the low bits set means error value,
1783 * ie
1784 *      if (ret & ~PAGE_MASK)
1785 *              error = ret;
1786 *
1787 * This function "knows" that -ENOMEM has the bits set.
1788 */
1789#ifndef HAVE_ARCH_UNMAPPED_AREA
1790unsigned long
1791arch_get_unmapped_area(struct file *filp, unsigned long addr,
1792                unsigned long len, unsigned long pgoff, unsigned long flags)
1793{
1794        struct mm_struct *mm = current->mm;
1795        struct vm_area_struct *vma;
1796        struct vm_unmapped_area_info info;
1797
1798        if (len > TASK_SIZE)
1799                return -ENOMEM;
1800
1801        if (flags & MAP_FIXED)
1802                return addr;
1803
1804        if (addr) {
1805                addr = PAGE_ALIGN(addr);
1806                vma = find_vma(mm, addr);
1807                if (TASK_SIZE - len >= addr &&
1808                    (!vma || addr + len <= vma->vm_start))
1809                        return addr;
1810        }
1811
1812        info.flags = 0;
1813        info.length = len;
1814        info.low_limit = TASK_UNMAPPED_BASE;
1815        info.high_limit = TASK_SIZE;
1816        info.align_mask = 0;
1817        return vm_unmapped_area(&info);
1818}
1819#endif  
1820
1821void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1822{
1823        /*
1824         * Is this a new hole at the lowest possible address?
1825         */
1826        if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache)
1827                mm->free_area_cache = addr;
1828}
1829
1830/*
1831 * This mmap-allocator allocates new areas top-down from below the
1832 * stack's low limit (the base):
1833 */
1834#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1835unsigned long
1836arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1837                          const unsigned long len, const unsigned long pgoff,
1838                          const unsigned long flags)
1839{
1840        struct vm_area_struct *vma;
1841        struct mm_struct *mm = current->mm;
1842        unsigned long addr = addr0;
1843        struct vm_unmapped_area_info info;
1844
1845        /* requested length too big for entire address space */
1846        if (len > TASK_SIZE)
1847                return -ENOMEM;
1848
1849        if (flags & MAP_FIXED)
1850                return addr;
1851
1852        /* requesting a specific address */
1853        if (addr) {
1854                addr = PAGE_ALIGN(addr);
1855                vma = find_vma(mm, addr);
1856                if (TASK_SIZE - len >= addr &&
1857                                (!vma || addr + len <= vma->vm_start))
1858                        return addr;
1859        }
1860
1861        info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1862        info.length = len;
1863        info.low_limit = PAGE_SIZE;
1864        info.high_limit = mm->mmap_base;
1865        info.align_mask = 0;
1866        addr = vm_unmapped_area(&info);
1867
1868        /*
1869         * A failed mmap() very likely causes application failure,
1870         * so fall back to the bottom-up function here. This scenario
1871         * can happen with large stack limits and large mmap()
1872         * allocations.
1873         */
1874        if (addr & ~PAGE_MASK) {
1875                VM_BUG_ON(addr != -ENOMEM);
1876                info.flags = 0;
1877                info.low_limit = TASK_UNMAPPED_BASE;
1878                info.high_limit = TASK_SIZE;
1879                addr = vm_unmapped_area(&info);
1880        }
1881
1882        return addr;
1883}
1884#endif
1885
1886void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1887{
1888        /*
1889         * Is this a new hole at the highest possible address?
1890         */
1891        if (addr > mm->free_area_cache)
1892                mm->free_area_cache = addr;
1893
1894        /* dont allow allocations above current base */
1895        if (mm->free_area_cache > mm->mmap_base)
1896                mm->free_area_cache = mm->mmap_base;
1897}
1898
1899unsigned long
1900get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1901                unsigned long pgoff, unsigned long flags)
1902{
1903        unsigned long (*get_area)(struct file *, unsigned long,
1904                                  unsigned long, unsigned long, unsigned long);
1905
1906        unsigned long error = arch_mmap_check(addr, len, flags);
1907        if (error)
1908                return error;
1909
1910        /* Careful about overflows.. */
1911        if (len > TASK_SIZE)
1912                return -ENOMEM;
1913
1914        get_area = current->mm->get_unmapped_area;
1915        if (file && file->f_op && file->f_op->get_unmapped_area)
1916                get_area = file->f_op->get_unmapped_area;
1917        addr = get_area(file, addr, len, pgoff, flags);
1918        if (IS_ERR_VALUE(addr))
1919                return addr;
1920
1921        if (addr > TASK_SIZE - len)
1922                return -ENOMEM;
1923        if (addr & ~PAGE_MASK)
1924                return -EINVAL;
1925
1926        addr = arch_rebalance_pgtables(addr, len);
1927        error = security_mmap_addr(addr);
1928        return error ? error : addr;
1929}
1930
1931EXPORT_SYMBOL(get_unmapped_area);
1932
1933/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1934struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1935{
1936        struct vm_area_struct *vma = NULL;
1937
1938        if (WARN_ON_ONCE(!mm))          /* Remove this in linux-3.6 */
1939                return NULL;
1940
1941        /* Check the cache first. */
1942        /* (Cache hit rate is typically around 35%.) */
1943        vma = ACCESS_ONCE(mm->mmap_cache);
1944        if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1945                struct rb_node *rb_node;
1946
1947                rb_node = mm->mm_rb.rb_node;
1948                vma = NULL;
1949
1950                while (rb_node) {
1951                        struct vm_area_struct *vma_tmp;
1952
1953                        vma_tmp = rb_entry(rb_node,
1954                                           struct vm_area_struct, vm_rb);
1955
1956                        if (vma_tmp->vm_end > addr) {
1957                                vma = vma_tmp;
1958                                if (vma_tmp->vm_start <= addr)
1959                                        break;
1960                                rb_node = rb_node->rb_left;
1961                        } else
1962                                rb_node = rb_node->rb_right;
1963                }
1964                if (vma)
1965                        mm->mmap_cache = vma;
1966        }
1967        return vma;
1968}
1969
1970EXPORT_SYMBOL(find_vma);
1971
1972/*
1973 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
1974 */
1975struct vm_area_struct *
1976find_vma_prev(struct mm_struct *mm, unsigned long addr,
1977                        struct vm_area_struct **pprev)
1978{
1979        struct vm_area_struct *vma;
1980
1981        vma = find_vma(mm, addr);
1982        if (vma) {
1983                *pprev = vma->vm_prev;
1984        } else {
1985                struct rb_node *rb_node = mm->mm_rb.rb_node;
1986                *pprev = NULL;
1987                while (rb_node) {
1988                        *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1989                        rb_node = rb_node->rb_right;
1990                }
1991        }
1992        return vma;
1993}
1994
1995/*
1996 * Verify that the stack growth is acceptable and
1997 * update accounting. This is shared with both the
1998 * grow-up and grow-down cases.
1999 */
2000static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2001{
2002        struct mm_struct *mm = vma->vm_mm;
2003        struct rlimit *rlim = current->signal->rlim;
2004        unsigned long new_start;
2005
2006        /* address space limit tests */
2007        if (!may_expand_vm(mm, grow))
2008                return -ENOMEM;
2009
2010        /* Stack limit test */
2011        if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2012                return -ENOMEM;
2013
2014        /* mlock limit tests */
2015        if (vma->vm_flags & VM_LOCKED) {
2016                unsigned long locked;
2017                unsigned long limit;
2018                locked = mm->locked_vm + grow;
2019                limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2020                limit >>= PAGE_SHIFT;
2021                if (locked > limit && !capable(CAP_IPC_LOCK))
2022                        return -ENOMEM;
2023        }
2024
2025        /* Check to ensure the stack will not grow into a hugetlb-only region */
2026        new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2027                        vma->vm_end - size;
2028        if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2029                return -EFAULT;
2030
2031        /*
2032         * Overcommit..  This must be the final test, as it will
2033         * update security statistics.
2034         */
2035        if (security_vm_enough_memory_mm(mm, grow))
2036                return -ENOMEM;
2037
2038        /* Ok, everything looks good - let it rip */
2039        if (vma->vm_flags & VM_LOCKED)
2040                mm->locked_vm += grow;
2041        vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
2042        return 0;
2043}
2044
2045#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2046/*
2047 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2048 * vma is the last one with address > vma->vm_end.  Have to extend vma.
2049 */
2050int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2051{
2052        int error;
2053
2054        if (!(vma->vm_flags & VM_GROWSUP))
2055                return -EFAULT;
2056
2057        /*
2058         * We must make sure the anon_vma is allocated
2059         * so that the anon_vma locking is not a noop.
2060         */
2061        if (unlikely(anon_vma_prepare(vma)))
2062                return -ENOMEM;
2063        vma_lock_anon_vma(vma);
2064
2065        /*
2066         * vma->vm_start/vm_end cannot change under us because the caller
2067         * is required to hold the mmap_sem in read mode.  We need the
2068         * anon_vma lock to serialize against concurrent expand_stacks.
2069         * Also guard against wrapping around to address 0.
2070         */
2071        if (address < PAGE_ALIGN(address+4))
2072                address = PAGE_ALIGN(address+4);
2073        else {
2074                vma_unlock_anon_vma(vma);
2075                return -ENOMEM;
2076        }
2077        error = 0;
2078
2079        /* Somebody else might have raced and expanded it already */
2080        if (address > vma->vm_end) {
2081                unsigned long size, grow;
2082
2083                size = address - vma->vm_start;
2084                grow = (address - vma->vm_end) >> PAGE_SHIFT;
2085
2086                error = -ENOMEM;
2087                if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2088                        error = acct_stack_growth(vma, size, grow);
2089                        if (!error) {
2090                                /*
2091                                 * vma_gap_update() doesn't support concurrent
2092                                 * updates, but we only hold a shared mmap_sem
2093                                 * lock here, so we need to protect against
2094                                 * concurrent vma expansions.
2095                                 * vma_lock_anon_vma() doesn't help here, as
2096                                 * we don't guarantee that all growable vmas
2097                                 * in a mm share the same root anon vma.
2098                                 * So, we reuse mm->page_table_lock to guard
2099                                 * against concurrent vma expansions.
2100                                 */
2101                                spin_lock(&vma->vm_mm->page_table_lock);
2102                                anon_vma_interval_tree_pre_update_vma(vma);
2103                                vma->vm_end = address;
2104                                anon_vma_interval_tree_post_update_vma(vma);
2105                                if (vma->vm_next)
2106                                        vma_gap_update(vma->vm_next);
2107                                else
2108                                        vma->vm_mm->highest_vm_end = address;
2109                                spin_unlock(&vma->vm_mm->page_table_lock);
2110
2111                                perf_event_mmap(vma);
2112                        }
2113                }
2114        }
2115        vma_unlock_anon_vma(vma);
2116        khugepaged_enter_vma_merge(vma);
2117        validate_mm(vma->vm_mm);
2118        return error;
2119}
2120#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2121
2122/*
2123 * vma is the first one with address < vma->vm_start.  Have to extend vma.
2124 */
2125int expand_downwards(struct vm_area_struct *vma,
2126                                   unsigned long address)
2127{
2128        int error;
2129
2130        /*
2131         * We must make sure the anon_vma is allocated
2132         * so that the anon_vma locking is not a noop.
2133         */
2134        if (unlikely(anon_vma_prepare(vma)))
2135                return -ENOMEM;
2136
2137        address &= PAGE_MASK;
2138        error = security_mmap_addr(address);
2139        if (error)
2140                return error;
2141
2142        vma_lock_anon_vma(vma);
2143
2144        /*
2145         * vma->vm_start/vm_end cannot change under us because the caller
2146         * is required to hold the mmap_sem in read mode.  We need the
2147         * anon_vma lock to serialize against concurrent expand_stacks.
2148         */
2149
2150        /* Somebody else might have raced and expanded it already */
2151        if (address < vma->vm_start) {
2152                unsigned long size, grow;
2153
2154                size = vma->vm_end - address;
2155                grow = (vma->vm_start - address) >> PAGE_SHIFT;
2156
2157                error = -ENOMEM;
2158                if (grow <= vma->vm_pgoff) {
2159                        error = acct_stack_growth(vma, size, grow);
2160                        if (!error) {
2161                                /*
2162                                 * vma_gap_update() doesn't support concurrent
2163                                 * updates, but we only hold a shared mmap_sem
2164                                 * lock here, so we need to protect against
2165                                 * concurrent vma expansions.
2166                                 * vma_lock_anon_vma() doesn't help here, as
2167                                 * we don't guarantee that all growable vmas
2168                                 * in a mm share the same root anon vma.
2169                                 * So, we reuse mm->page_table_lock to guard
2170                                 * against concurrent vma expansions.
2171                                 */
2172                                spin_lock(&vma->vm_mm->page_table_lock);
2173                                anon_vma_interval_tree_pre_update_vma(vma);
2174                                vma->vm_start = address;
2175                                vma->vm_pgoff -= grow;
2176                                anon_vma_interval_tree_post_update_vma(vma);
2177                                vma_gap_update(vma);
2178                                spin_unlock(&vma->vm_mm->page_table_lock);
2179
2180                                perf_event_mmap(vma);
2181                        }
2182                }
2183        }
2184        vma_unlock_anon_vma(vma);
2185        khugepaged_enter_vma_merge(vma);
2186        validate_mm(vma->vm_mm);
2187        return error;
2188}
2189
2190/*
2191 * Note how expand_stack() refuses to expand the stack all the way to
2192 * abut the next virtual mapping, *unless* that mapping itself is also
2193 * a stack mapping. We want to leave room for a guard page, after all
2194 * (the guard page itself is not added here, that is done by the
2195 * actual page faulting logic)
2196 *
2197 * This matches the behavior of the guard page logic (see mm/memory.c:
2198 * check_stack_guard_page()), which only allows the guard page to be
2199 * removed under these circumstances.
2200 */
2201#ifdef CONFIG_STACK_GROWSUP
2202int expand_stack(struct vm_area_struct *vma, unsigned long address)
2203{
2204        struct vm_area_struct *next;
2205
2206        address &= PAGE_MASK;
2207        next = vma->vm_next;
2208        if (next && next->vm_start == address + PAGE_SIZE) {
2209                if (!(next->vm_flags & VM_GROWSUP))
2210                        return -ENOMEM;
2211        }
2212        return expand_upwards(vma, address);
2213}
2214
2215struct vm_area_struct *
2216find_extend_vma(struct mm_struct *mm, unsigned long addr)
2217{
2218        struct vm_area_struct *vma, *prev;
2219
2220        addr &= PAGE_MASK;
2221        vma = find_vma_prev(mm, addr, &prev);
2222        if (vma && (vma->vm_start <= addr))
2223                return vma;
2224        if (!prev || expand_stack(prev, addr))
2225                return NULL;
2226        if (prev->vm_flags & VM_LOCKED)
2227                __mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2228        return prev;
2229}
2230#else
2231int expand_stack(struct vm_area_struct *vma, unsigned long address)
2232{
2233        struct vm_area_struct *prev;
2234
2235        address &= PAGE_MASK;
2236        prev = vma->vm_prev;
2237        if (prev && prev->vm_end == address) {
2238                if (!(prev->vm_flags & VM_GROWSDOWN))
2239                        return -ENOMEM;
2240        }
2241        return expand_downwards(vma, address);
2242}
2243
2244struct vm_area_struct *
2245find_extend_vma(struct mm_struct * mm, unsigned long addr)
2246{
2247        struct vm_area_struct * vma;
2248        unsigned long start;
2249
2250        addr &= PAGE_MASK;
2251        vma = find_vma(mm,addr);
2252        if (!vma)
2253                return NULL;
2254        if (vma->vm_start <= addr)
2255                return vma;
2256        if (!(vma->vm_flags & VM_GROWSDOWN))
2257                return NULL;
2258        start = vma->vm_start;
2259        if (expand_stack(vma, addr))
2260                return NULL;
2261        if (vma->vm_flags & VM_LOCKED)
2262                __mlock_vma_pages_range(vma, addr, start, NULL);
2263        return vma;
2264}
2265#endif
2266
2267/*
2268 * Ok - we have the memory areas we should free on the vma list,
2269 * so release them, and do the vma updates.
2270 *
2271 * Called with the mm semaphore held.
2272 */
2273static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2274{
2275        unsigned long nr_accounted = 0;
2276
2277        /* Update high watermark before we lower total_vm */
2278        update_hiwater_vm(mm);
2279        do {
2280                long nrpages = vma_pages(vma);
2281
2282                if (vma->vm_flags & VM_ACCOUNT)
2283                        nr_accounted += nrpages;
2284                vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2285                vma = remove_vma(vma);
2286        } while (vma);
2287        vm_unacct_memory(nr_accounted);
2288        validate_mm(mm);
2289}
2290
2291/*
2292 * Get rid of page table information in the indicated region.
2293 *
2294 * Called with the mm semaphore held.
2295 */
2296static void unmap_region(struct mm_struct *mm,
2297                struct vm_area_struct *vma, struct vm_area_struct *prev,
2298                unsigned long start, unsigned long end)
2299{
2300        struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
2301        struct mmu_gather tlb;
2302
2303        lru_add_drain();
2304        tlb_gather_mmu(&tlb, mm, 0);
2305        update_hiwater_rss(mm);
2306        unmap_vmas(&tlb, vma, start, end);
2307        free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2308                                 next ? next->vm_start : 0);
2309        tlb_finish_mmu(&tlb, start, end);
2310}
2311
2312/*
2313 * Create a list of vma's touched by the unmap, removing them from the mm's
2314 * vma list as we go..
2315 */
2316static void
2317detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2318        struct vm_area_struct *prev, unsigned long end)
2319{
2320        struct vm_area_struct **insertion_point;
2321        struct vm_area_struct *tail_vma = NULL;
2322        unsigned long addr;
2323
2324        insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2325        vma->vm_prev = NULL;
2326        do {
2327                vma_rb_erase(vma, &mm->mm_rb);
2328                mm->map_count--;
2329                tail_vma = vma;
2330                vma = vma->vm_next;
2331        } while (vma && vma->vm_start < end);
2332        *insertion_point = vma;
2333        if (vma) {
2334                vma->vm_prev = prev;
2335                vma_gap_update(vma);
2336        } else
2337                mm->highest_vm_end = prev ? prev->vm_end : 0;
2338        tail_vma->vm_next = NULL;
2339        if (mm->unmap_area == arch_unmap_area)
2340                addr = prev ? prev->vm_end : mm->mmap_base;
2341        else
2342                addr = vma ?  vma->vm_start : mm->mmap_base;
2343        mm->unmap_area(mm, addr);
2344        mm->mmap_cache = NULL;          /* Kill the cache. */
2345}
2346
2347/*
2348 * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
2349 * munmap path where it doesn't make sense to fail.
2350 */
2351static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
2352              unsigned long addr, int new_below)
2353{
2354        struct mempolicy *pol;
2355        struct vm_area_struct *new;
2356        int err = -ENOMEM;
2357
2358        if (is_vm_hugetlb_page(vma) && (addr &
2359                                        ~(huge_page_mask(hstate_vma(vma)))))
2360                return -EINVAL;
2361
2362        new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2363        if (!new)
2364                goto out_err;
2365
2366        /* most fields are the same, copy all, and then fixup */
2367        *new = *vma;
2368
2369        INIT_LIST_HEAD(&new->anon_vma_chain);
2370
2371        if (new_below)
2372                new->vm_end = addr;
2373        else {
2374                new->vm_start = addr;
2375                new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2376        }
2377
2378        pol = mpol_dup(vma_policy(vma));
2379        if (IS_ERR(pol)) {
2380                err = PTR_ERR(pol);
2381                goto out_free_vma;
2382        }
2383        vma_set_policy(new, pol);
2384
2385        if (anon_vma_clone(new, vma))
2386                goto out_free_mpol;
2387
2388        if (new->vm_file)
2389                get_file(new->vm_file);
2390
2391        if (new->vm_ops && new->vm_ops->open)
2392                new->vm_ops->open(new);
2393
2394        if (new_below)
2395                err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2396                        ((addr - new->vm_start) >> PAGE_SHIFT), new);
2397        else
2398                err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2399
2400        /* Success. */
2401        if (!err)
2402                return 0;
2403
2404        /* Clean everything up if vma_adjust failed. */
2405        if (new->vm_ops && new->vm_ops->close)
2406                new->vm_ops->close(new);
2407        if (new->vm_file)
2408                fput(new->vm_file);
2409        unlink_anon_vmas(new);
2410 out_free_mpol:
2411        mpol_put(pol);
2412 out_free_vma:
2413        kmem_cache_free(vm_area_cachep, new);
2414 out_err:
2415        return err;
2416}
2417
2418/*
2419 * Split a vma into two pieces at address 'addr', a new vma is allocated
2420 * either for the first part or the tail.
2421 */
2422int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2423              unsigned long addr, int new_below)
2424{
2425        if (mm->map_count >= sysctl_max_map_count)
2426                return -ENOMEM;
2427
2428        return __split_vma(mm, vma, addr, new_below);
2429}
2430
2431/* Munmap is split into 2 main parts -- this part which finds
2432 * what needs doing, and the areas themselves, which do the
2433 * work.  This now handles partial unmappings.
2434 * Jeremy Fitzhardinge <jeremy@goop.org>
2435 */
2436int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2437{
2438        unsigned long end;
2439        struct vm_area_struct *vma, *prev, *last;
2440
2441        if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2442                return -EINVAL;
2443
2444        if ((len = PAGE_ALIGN(len)) == 0)
2445                return -EINVAL;
2446
2447        /* Find the first overlapping VMA */
2448        vma = find_vma(mm, start);
2449        if (!vma)
2450                return 0;
2451        prev = vma->vm_prev;
2452        /* we have  start < vma->vm_end  */
2453
2454        /* if it doesn't overlap, we have nothing.. */
2455        end = start + len;
2456        if (vma->vm_start >= end)
2457                return 0;
2458
2459        /*
2460         * If we need to split any vma, do it now to save pain later.
2461         *
2462         * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2463         * unmapped vm_area_struct will remain in use: so lower split_vma
2464         * places tmp vma above, and higher split_vma places tmp vma below.
2465         */
2466        if (start > vma->vm_start) {
2467                int error;
2468
2469                /*
2470                 * Make sure that map_count on return from munmap() will
2471                 * not exceed its limit; but let map_count go just above
2472                 * its limit temporarily, to help free resources as expected.
2473                 */
2474                if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2475                        return -ENOMEM;
2476
2477                error = __split_vma(mm, vma, start, 0);
2478                if (error)
2479                        return error;
2480                prev = vma;
2481        }
2482
2483        /* Does it split the last one? */
2484        last = find_vma(mm, end);
2485        if (last && end > last->vm_start) {
2486                int error = __split_vma(mm, last, end, 1);
2487                if (error)
2488                        return error;
2489        }
2490        vma = prev? prev->vm_next: mm->mmap;
2491
2492        /*
2493         * unlock any mlock()ed ranges before detaching vmas
2494         */
2495        if (mm->locked_vm) {
2496                struct vm_area_struct *tmp = vma;
2497                while (tmp && tmp->vm_start < end) {
2498                        if (tmp->vm_flags & VM_LOCKED) {
2499                                mm->locked_vm -= vma_pages(tmp);
2500                                munlock_vma_pages_all(tmp);
2501                        }
2502                        tmp = tmp->vm_next;
2503                }
2504        }
2505
2506        /*
2507         * Remove the vma's, and unmap the actual pages
2508         */
2509        detach_vmas_to_be_unmapped(mm, vma, prev, end);
2510        unmap_region(mm, vma, prev, start, end);
2511
2512        /* Fix up all other VM information */
2513        remove_vma_list(mm, vma);
2514
2515        return 0;
2516}
2517
2518int vm_munmap(unsigned long start, size_t len)
2519{
2520        int ret;
2521        struct mm_struct *mm = current->mm;
2522
2523        down_write(&mm->mmap_sem);
2524        ret = do_munmap(mm, start, len);
2525        up_write(&mm->mmap_sem);
2526        return ret;
2527}
2528EXPORT_SYMBOL(vm_munmap);
2529
2530SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2531{
2532        profile_munmap(addr);
2533        return vm_munmap(addr, len);
2534}
2535
2536static inline void verify_mm_writelocked(struct mm_struct *mm)
2537{
2538#ifdef CONFIG_DEBUG_VM
2539        if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2540                WARN_ON(1);
2541                up_read(&mm->mmap_sem);
2542        }
2543#endif
2544}
2545
2546/*
2547 *  this is really a simplified "do_mmap".  it only handles
2548 *  anonymous maps.  eventually we may be able to do some
2549 *  brk-specific accounting here.
2550 */
2551static unsigned long do_brk(unsigned long addr, unsigned long len)
2552{
2553        struct mm_struct * mm = current->mm;
2554        struct vm_area_struct * vma, * prev;
2555        unsigned long flags;
2556        struct rb_node ** rb_link, * rb_parent;
2557        pgoff_t pgoff = addr >> PAGE_SHIFT;
2558        int error;
2559
2560        len = PAGE_ALIGN(len);
2561        if (!len)
2562                return addr;
2563
2564        flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2565
2566        error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2567        if (error & ~PAGE_MASK)
2568                return error;
2569
2570        /*
2571         * mlock MCL_FUTURE?
2572         */
2573        if (mm->def_flags & VM_LOCKED) {
2574                unsigned long locked, lock_limit;
2575                locked = len >> PAGE_SHIFT;
2576                locked += mm->locked_vm;
2577                lock_limit = rlimit(RLIMIT_MEMLOCK);
2578                lock_limit >>= PAGE_SHIFT;
2579                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2580                        return -EAGAIN;
2581        }
2582
2583        /*
2584         * mm->mmap_sem is required to protect against another thread
2585         * changing the mappings in case we sleep.
2586         */
2587        verify_mm_writelocked(mm);
2588
2589        /*
2590         * Clear old maps.  this also does some error checking for us
2591         */
2592 munmap_back:
2593        if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
2594                if (do_munmap(mm, addr, len))
2595                        return -ENOMEM;
2596                goto munmap_back;
2597        }
2598
2599        /* Check against address space limits *after* clearing old maps... */
2600        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2601                return -ENOMEM;
2602
2603        if (mm->map_count > sysctl_max_map_count)
2604                return -ENOMEM;
2605
2606        if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2607                return -ENOMEM;
2608
2609        /* Can we just expand an old private anonymous mapping? */
2610        vma = vma_merge(mm, prev, addr, addr + len, flags,
2611                                        NULL, NULL, pgoff, NULL);
2612        if (vma)
2613                goto out;
2614
2615        /*
2616         * create a vma struct for an anonymous mapping
2617         */
2618        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2619        if (!vma) {
2620                vm_unacct_memory(len >> PAGE_SHIFT);
2621                return -ENOMEM;
2622        }
2623
2624        INIT_LIST_HEAD(&vma->anon_vma_chain);
2625        vma->vm_mm = mm;
2626        vma->vm_start = addr;
2627        vma->vm_end = addr + len;
2628        vma->vm_pgoff = pgoff;
2629        vma->vm_flags = flags;
2630        vma->vm_page_prot = vm_get_page_prot(flags);
2631        vma_link(mm, vma, prev, rb_link, rb_parent);
2632out:
2633        perf_event_mmap(vma);
2634        mm->total_vm += len >> PAGE_SHIFT;
2635        if (flags & VM_LOCKED)
2636                mm->locked_vm += (len >> PAGE_SHIFT);
2637        return addr;
2638}
2639
2640unsigned long vm_brk(unsigned long addr, unsigned long len)
2641{
2642        struct mm_struct *mm = current->mm;
2643        unsigned long ret;
2644        bool populate;
2645
2646        down_write(&mm->mmap_sem);
2647        ret = do_brk(addr, len);
2648        populate = ((mm->def_flags & VM_LOCKED) != 0);
2649        up_write(&mm->mmap_sem);
2650        if (populate)
2651                mm_populate(addr, len);
2652        return ret;
2653}
2654EXPORT_SYMBOL(vm_brk);
2655
2656/* Release all mmaps. */
2657void exit_mmap(struct mm_struct *mm)
2658{
2659        struct mmu_gather tlb;
2660        struct vm_area_struct *vma;
2661        unsigned long nr_accounted = 0;
2662
2663        /* mm's last user has gone, and its about to be pulled down */
2664        mmu_notifier_release(mm);
2665
2666        if (mm->locked_vm) {
2667                vma = mm->mmap;
2668                while (vma) {
2669                        if (vma->vm_flags & VM_LOCKED)
2670                                munlock_vma_pages_all(vma);
2671                        vma = vma->vm_next;
2672                }
2673        }
2674
2675        arch_exit_mmap(mm);
2676
2677        vma = mm->mmap;
2678        if (!vma)       /* Can happen if dup_mmap() received an OOM */
2679                return;
2680
2681        lru_add_drain();
2682        flush_cache_mm(mm);
2683        tlb_gather_mmu(&tlb, mm, 1);
2684        /* update_hiwater_rss(mm) here? but nobody should be looking */
2685        /* Use -1 here to ensure all VMAs in the mm are unmapped */
2686        unmap_vmas(&tlb, vma, 0, -1);
2687
2688        free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2689        tlb_finish_mmu(&tlb, 0, -1);
2690
2691        /*
2692         * Walk the list again, actually closing and freeing it,
2693         * with preemption enabled, without holding any MM locks.
2694         */
2695        while (vma) {
2696                if (vma->vm_flags & VM_ACCOUNT)
2697                        nr_accounted += vma_pages(vma);
2698                vma = remove_vma(vma);
2699        }
2700        vm_unacct_memory(nr_accounted);
2701
2702        WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2703}
2704
2705/* Insert vm structure into process list sorted by address
2706 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2707 * then i_mmap_mutex is taken here.
2708 */
2709int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2710{
2711        struct vm_area_struct *prev;
2712        struct rb_node **rb_link, *rb_parent;
2713
2714        /*
2715         * The vm_pgoff of a purely anonymous vma should be irrelevant
2716         * until its first write fault, when page's anon_vma and index
2717         * are set.  But now set the vm_pgoff it will almost certainly
2718         * end up with (unless mremap moves it elsewhere before that
2719         * first wfault), so /proc/pid/maps tells a consistent story.
2720         *
2721         * By setting it to reflect the virtual start address of the
2722         * vma, merges and splits can happen in a seamless way, just
2723         * using the existing file pgoff checks and manipulations.
2724         * Similarly in do_mmap_pgoff and in do_brk.
2725         */
2726        if (!vma->vm_file) {
2727                BUG_ON(vma->anon_vma);
2728                vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2729        }
2730        if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2731                           &prev, &rb_link, &rb_parent))
2732                return -ENOMEM;
2733        if ((vma->vm_flags & VM_ACCOUNT) &&
2734             security_vm_enough_memory_mm(mm, vma_pages(vma)))
2735                return -ENOMEM;
2736
2737        vma_link(mm, vma, prev, rb_link, rb_parent);
2738        return 0;
2739}
2740
2741/*
2742 * Copy the vma structure to a new location in the same mm,
2743 * prior to moving page table entries, to effect an mremap move.
2744 */
2745struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2746        unsigned long addr, unsigned long len, pgoff_t pgoff,
2747        bool *need_rmap_locks)
2748{
2749        struct vm_area_struct *vma = *vmap;
2750        unsigned long vma_start = vma->vm_start;
2751        struct mm_struct *mm = vma->vm_mm;
2752        struct vm_area_struct *new_vma, *prev;
2753        struct rb_node **rb_link, *rb_parent;
2754        struct mempolicy *pol;
2755        bool faulted_in_anon_vma = true;
2756
2757        /*
2758         * If anonymous vma has not yet been faulted, update new pgoff
2759         * to match new location, to increase its chance of merging.
2760         */
2761        if (unlikely(!vma->vm_file && !vma->anon_vma)) {
2762                pgoff = addr >> PAGE_SHIFT;
2763                faulted_in_anon_vma = false;
2764        }
2765
2766        if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2767                return NULL;    /* should never get here */
2768        new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2769                        vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2770        if (new_vma) {
2771                /*
2772                 * Source vma may have been merged into new_vma
2773                 */
2774                if (unlikely(vma_start >= new_vma->vm_start &&
2775                             vma_start < new_vma->vm_end)) {
2776                        /*
2777                         * The only way we can get a vma_merge with
2778                         * self during an mremap is if the vma hasn't
2779                         * been faulted in yet and we were allowed to
2780                         * reset the dst vma->vm_pgoff to the
2781                         * destination address of the mremap to allow
2782                         * the merge to happen. mremap must change the
2783                         * vm_pgoff linearity between src and dst vmas
2784                         * (in turn preventing a vma_merge) to be
2785                         * safe. It is only safe to keep the vm_pgoff
2786                         * linear if there are no pages mapped yet.
2787                         */
2788                        VM_BUG_ON(faulted_in_anon_vma);
2789                        *vmap = vma = new_vma;
2790                }
2791                *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2792        } else {
2793                new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2794                if (new_vma) {
2795                        *new_vma = *vma;
2796                        new_vma->vm_start = addr;
2797                        new_vma->vm_end = addr + len;
2798                        new_vma->vm_pgoff = pgoff;
2799                        pol = mpol_dup(vma_policy(vma));
2800                        if (IS_ERR(pol))
2801                                goto out_free_vma;
2802                        vma_set_policy(new_vma, pol);
2803                        INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2804                        if (anon_vma_clone(new_vma, vma))
2805                                goto out_free_mempol;
2806                        if (new_vma->vm_file)
2807                                get_file(new_vma->vm_file);
2808                        if (new_vma->vm_ops && new_vma->vm_ops->open)
2809                                new_vma->vm_ops->open(new_vma);
2810                        vma_link(mm, new_vma, prev, rb_link, rb_parent);
2811                        *need_rmap_locks = false;
2812                }
2813        }
2814        return new_vma;
2815
2816 out_free_mempol:
2817        mpol_put(pol);
2818 out_free_vma:
2819        kmem_cache_free(vm_area_cachep, new_vma);
2820        return NULL;
2821}
2822
2823/*
2824 * Return true if the calling process may expand its vm space by the passed
2825 * number of pages
2826 */
2827int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2828{
2829        unsigned long cur = mm->total_vm;       /* pages */
2830        unsigned long lim;
2831
2832        lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2833
2834        if (cur + npages > lim)
2835                return 0;
2836        return 1;
2837}
2838
2839
2840static int special_mapping_fault(struct vm_area_struct *vma,
2841                                struct vm_fault *vmf)
2842{
2843        pgoff_t pgoff;
2844        struct page **pages;
2845
2846        /*
2847         * special mappings have no vm_file, and in that case, the mm
2848         * uses vm_pgoff internally. So we have to subtract it from here.
2849         * We are allowed to do this because we are the mm; do not copy
2850         * this code into drivers!
2851         */
2852        pgoff = vmf->pgoff - vma->vm_pgoff;
2853
2854        for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2855                pgoff--;
2856
2857        if (*pages) {
2858                struct page *page = *pages;
2859                get_page(page);
2860                vmf->page = page;
2861                return 0;
2862        }
2863
2864        return VM_FAULT_SIGBUS;
2865}
2866
2867/*
2868 * Having a close hook prevents vma merging regardless of flags.
2869 */
2870static void special_mapping_close(struct vm_area_struct *vma)
2871{
2872}
2873
2874static const struct vm_operations_struct special_mapping_vmops = {
2875        .close = special_mapping_close,
2876        .fault = special_mapping_fault,
2877};
2878
2879/*
2880 * Called with mm->mmap_sem held for writing.
2881 * Insert a new vma covering the given region, with the given flags.
2882 * Its pages are supplied by the given array of struct page *.
2883 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2884 * The region past the last page supplied will always produce SIGBUS.
2885 * The array pointer and the pages it points to are assumed to stay alive
2886 * for as long as this mapping might exist.
2887 */
2888int install_special_mapping(struct mm_struct *mm,
2889                            unsigned long addr, unsigned long len,
2890                            unsigned long vm_flags, struct page **pages)
2891{
2892        int ret;
2893        struct vm_area_struct *vma;
2894
2895        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2896        if (unlikely(vma == NULL))
2897                return -ENOMEM;
2898
2899        INIT_LIST_HEAD(&vma->anon_vma_chain);
2900        vma->vm_mm = mm;
2901        vma->vm_start = addr;
2902        vma->vm_end = addr + len;
2903
2904        vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2905        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2906
2907        vma->vm_ops = &special_mapping_vmops;
2908        vma->vm_private_data = pages;
2909
2910        ret = insert_vm_struct(mm, vma);
2911        if (ret)
2912                goto out;
2913
2914        mm->total_vm += len >> PAGE_SHIFT;
2915
2916        perf_event_mmap(vma);
2917
2918        return 0;
2919
2920out:
2921        kmem_cache_free(vm_area_cachep, vma);
2922        return ret;
2923}
2924
2925static DEFINE_MUTEX(mm_all_locks_mutex);
2926
2927static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2928{
2929        if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
2930                /*
2931                 * The LSB of head.next can't change from under us
2932                 * because we hold the mm_all_locks_mutex.
2933                 */
2934                down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
2935                /*
2936                 * We can safely modify head.next after taking the
2937                 * anon_vma->root->rwsem. If some other vma in this mm shares
2938                 * the same anon_vma we won't take it again.
2939                 *
2940                 * No need of atomic instructions here, head.next
2941                 * can't change from under us thanks to the
2942                 * anon_vma->root->rwsem.
2943                 */
2944                if (__test_and_set_bit(0, (unsigned long *)
2945                                       &anon_vma->root->rb_root.rb_node))
2946                        BUG();
2947        }
2948}
2949
2950static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2951{
2952        if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2953                /*
2954                 * AS_MM_ALL_LOCKS can't change from under us because
2955                 * we hold the mm_all_locks_mutex.
2956                 *
2957                 * Operations on ->flags have to be atomic because
2958                 * even if AS_MM_ALL_LOCKS is stable thanks to the
2959                 * mm_all_locks_mutex, there may be other cpus
2960                 * changing other bitflags in parallel to us.
2961                 */
2962                if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2963                        BUG();
2964                mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
2965        }
2966}
2967
2968/*
2969 * This operation locks against the VM for all pte/vma/mm related
2970 * operations that could ever happen on a certain mm. This includes
2971 * vmtruncate, try_to_unmap, and all page faults.
2972 *
2973 * The caller must take the mmap_sem in write mode before calling
2974 * mm_take_all_locks(). The caller isn't allowed to release the
2975 * mmap_sem until mm_drop_all_locks() returns.
2976 *
2977 * mmap_sem in write mode is required in order to block all operations
2978 * that could modify pagetables and free pages without need of
2979 * altering the vma layout (for example populate_range() with
2980 * nonlinear vmas). It's also needed in write mode to avoid new
2981 * anon_vmas to be associated with existing vmas.
2982 *
2983 * A single task can't take more than one mm_take_all_locks() in a row
2984 * or it would deadlock.
2985 *
2986 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
2987 * mapping->flags avoid to take the same lock twice, if more than one
2988 * vma in this mm is backed by the same anon_vma or address_space.
2989 *
2990 * We can take all the locks in random order because the VM code
2991 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
2992 * takes more than one of them in a row. Secondly we're protected
2993 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2994 *
2995 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2996 * that may have to take thousand of locks.
2997 *
2998 * mm_take_all_locks() can fail if it's interrupted by signals.
2999 */
3000int mm_take_all_locks(struct mm_struct *mm)
3001{
3002        struct vm_area_struct *vma;
3003        struct anon_vma_chain *avc;
3004
3005        BUG_ON(down_read_trylock(&mm->mmap_sem));
3006
3007        mutex_lock(&mm_all_locks_mutex);
3008
3009        for (vma = mm->mmap; vma; vma = vma->vm_next) {
3010                if (signal_pending(current))
3011                        goto out_unlock;
3012                if (vma->vm_file && vma->vm_file->f_mapping)
3013                        vm_lock_mapping(mm, vma->vm_file->f_mapping);
3014        }
3015
3016        for (vma = mm->mmap; vma; vma = vma->vm_next) {
3017                if (signal_pending(current))
3018                        goto out_unlock;
3019                if (vma->anon_vma)
3020                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3021                                vm_lock_anon_vma(mm, avc->anon_vma);
3022        }
3023
3024        return 0;
3025
3026out_unlock:
3027        mm_drop_all_locks(mm);
3028        return -EINTR;
3029}
3030
3031static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3032{
3033        if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3034                /*
3035                 * The LSB of head.next can't change to 0 from under
3036                 * us because we hold the mm_all_locks_mutex.
3037                 *
3038                 * We must however clear the bitflag before unlocking
3039                 * the vma so the users using the anon_vma->rb_root will
3040                 * never see our bitflag.
3041                 *
3042                 * No need of atomic instructions here, head.next
3043                 * can't change from under us until we release the
3044                 * anon_vma->root->rwsem.
3045                 */
3046                if (!__test_and_clear_bit(0, (unsigned long *)
3047                                          &anon_vma->root->rb_root.rb_node))
3048                        BUG();
3049                anon_vma_unlock_write(anon_vma);
3050        }
3051}
3052
3053static void vm_unlock_mapping(struct address_space *mapping)
3054{
3055        if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3056                /*
3057                 * AS_MM_ALL_LOCKS can't change to 0 from under us
3058                 * because we hold the mm_all_locks_mutex.
3059                 */
3060                mutex_unlock(&mapping->i_mmap_mutex);
3061                if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3062                                        &mapping->flags))
3063                        BUG();
3064        }
3065}
3066
3067/*
3068 * The mmap_sem cannot be released by the caller until
3069 * mm_drop_all_locks() returns.
3070 */
3071void mm_drop_all_locks(struct mm_struct *mm)
3072{
3073        struct vm_area_struct *vma;
3074        struct anon_vma_chain *avc;
3075
3076        BUG_ON(down_read_trylock(&mm->mmap_sem));
3077        BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3078
3079        for (vma = mm->mmap; vma; vma = vma->vm_next) {
3080                if (vma->anon_vma)
3081                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3082                                vm_unlock_anon_vma(avc->anon_vma);
3083                if (vma->vm_file && vma->vm_file->f_mapping)
3084                        vm_unlock_mapping(vma->vm_file->f_mapping);
3085        }
3086
3087        mutex_unlock(&mm_all_locks_mutex);
3088}
3089
3090/*
3091 * initialise the VMA slab
3092 */
3093void __init mmap_init(void)
3094{
3095        int ret;
3096
3097        ret = percpu_counter_init(&vm_committed_as, 0);
3098        VM_BUG_ON(ret);
3099}
3100
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