mm/nommu.c

   1 /*
   2  *  linux/mm/nommu.c
   3  *
   4  *  Replacement code for mm functions to support CPU's that don't
   5  *  have any form of memory management unit (thus no virtual memory).
   6  *
   7  *  See Documentation/nommu-mmap.txt
   8  *
   9  *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
  10  *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
  11  *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
  12  *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
  13  *  Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org>
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/mm.h>
  18 #include <linux/mman.h>
  19 #include <linux/swap.h>
  20 #include <linux/file.h>
  21 #include <linux/highmem.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/slab.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/tracehook.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/backing-dev.h>
  28 #include <linux/mount.h>
  29 #include <linux/personality.h>
  30 #include <linux/security.h>
  31 #include <linux/syscalls.h>
  32
  33 #include <asm/uaccess.h>
  34 #include <asm/tlb.h>
  35 #include <asm/tlbflush.h>
  36 #include "internal.h"
  37
  38 static inline __attribute__((format(printf, 1, 2)))
  39 void no_printk(const char *fmt, ...)
  40 {
  41 }
  42
  43 #if 0
  44 #define kenter(FMT, ...) \
  45         printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  46 #define kleave(FMT, ...) \
  47         printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  48 #define kdebug(FMT, ...) \
  49         printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
  50 #else
  51 #define kenter(FMT, ...) \
  52         no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  53 #define kleave(FMT, ...) \
  54         no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  55 #define kdebug(FMT, ...) \
  56         no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
  57 #endif
  58
  59 #include "internal.h"
  60
  61 void *high_memory;
  62 struct page *mem_map;
  63 unsigned long max_mapnr;
  64 unsigned long num_physpages;
  65 struct percpu_counter vm_committed_as;
  66 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  67 int sysctl_overcommit_ratio = 50; /* default is 50% */
  68 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  69 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
  70 int heap_stack_gap = 0;
  71
  72 atomic_long_t mmap_pages_allocated;
  73
  74 EXPORT_SYMBOL(mem_map);
  75 EXPORT_SYMBOL(num_physpages);
  76
  77 /* list of mapped, potentially shareable regions */
  78 static struct kmem_cache *vm_region_jar;
  79 struct rb_root nommu_region_tree = RB_ROOT;
  80 DECLARE_RWSEM(nommu_region_sem);
  81
  82 struct vm_operations_struct generic_file_vm_ops = {
  83 };
  84
  85 /*
  86  * Handle all mappings that got truncated by a "truncate()"
  87  * system call.
  88  *
  89  * NOTE! We have to be ready to update the memory sharing
  90  * between the file and the memory map for a potential last
  91  * incomplete page.  Ugly, but necessary.
  92  */
  93 int vmtruncate(struct inode *inode, loff_t offset)
  94 {
  95         struct address_space *mapping = inode->i_mapping;
  96         unsigned long limit;
  97
  98         if (inode->i_size < offset)
  99                 goto do_expand;
 100         i_size_write(inode, offset);
 101
 102         truncate_inode_pages(mapping, offset);
 103         goto out_truncate;
 104
 105 do_expand:
 106         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
 107         if (limit != RLIM_INFINITY && offset > limit)
 108                 goto out_sig;
 109         if (offset > inode->i_sb->s_maxbytes)
 110                 goto out;
 111         i_size_write(inode, offset);
 112
 113 out_truncate:
 114         if (inode->i_op->truncate)
 115                 inode->i_op->truncate(inode);
 116         return 0;
 117 out_sig:
 118         send_sig(SIGXFSZ, current, 0);
 119 out:
 120         return -EFBIG;
 121 }
 122
 123 EXPORT_SYMBOL(vmtruncate);
 124
 125 /*
 126  * Return the total memory allocated for this pointer, not
 127  * just what the caller asked for.
 128  *
 129  * Doesn't have to be accurate, i.e. may have races.
 130  */
 131 unsigned int kobjsize(const void *objp)
 132 {
 133         struct page *page;
 134
 135         /*
 136          * If the object we have should not have ksize performed on it,
 137          * return size of 0
 138          */
 139         if (!objp || !virt_addr_valid(objp))
 140                 return 0;
 141
 142         page = virt_to_head_page(objp);
 143
 144         /*
 145          * If the allocator sets PageSlab, we know the pointer came from
 146          * kmalloc().
 147          */
 148         if (PageSlab(page))
 149                 return ksize(objp);
 150
 151         /*
 152          * If it's not a compound page, see if we have a matching VMA
 153          * region. This test is intentionally done in reverse order,
 154          * so if there's no VMA, we still fall through and hand back
 155          * PAGE_SIZE for 0-order pages.
 156          */
 157         if (!PageCompound(page)) {
 158                 struct vm_area_struct *vma;
 159
 160                 vma = find_vma(current->mm, (unsigned long)objp);
 161                 if (vma)
 162                         return vma->vm_end - vma->vm_start;
 163         }
 164
 165         /*
 166          * The ksize() function is only guaranteed to work for pointers
 167          * returned by kmalloc(). So handle arbitrary pointers here.
 168          */
 169         return PAGE_SIZE << compound_order(page);
 170 }
 171
 172 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 173                      unsigned long start, int nr_pages, int flags,
 174                      struct page **pages, struct vm_area_struct **vmas)
 175 {
 176         struct vm_area_struct *vma;
 177         unsigned long vm_flags;
 178         int i;
 179         int write = !!(flags & GUP_FLAGS_WRITE);
 180         int force = !!(flags & GUP_FLAGS_FORCE);
 181         int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
 182
 183         /* calculate required read or write permissions.
 184          * - if 'force' is set, we only require the "MAY" flags.
 185          */
 186         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 187         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 188
 189         for (i = 0; i < nr_pages; i++) {
 190                 vma = find_vma(mm, start);
 191                 if (!vma)
 192                         goto finish_or_fault;
 193
 194                 /* protect what we can, including chardevs */
 195                 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
 196                     (!ignore && !(vm_flags & vma->vm_flags)))
 197                         goto finish_or_fault;
 198
 199                 if (pages) {
 200                         pages[i] = virt_to_page(start);
 201                         if (pages[i])
 202                                 page_cache_get(pages[i]);
 203                 }
 204                 if (vmas)
 205                         vmas[i] = vma;
 206                 start += PAGE_SIZE;
 207         }
 208
 209         return i;
 210
 211 finish_or_fault:
 212         return i ? : -EFAULT;
 213 }
 214
 215
 216 /*
 217  * get a list of pages in an address range belonging to the specified process
 218  * and indicate the VMA that covers each page
 219  * - this is potentially dodgy as we may end incrementing the page count of a
 220  *   slab page or a secondary page from a compound page
 221  * - don't permit access to VMAs that don't support it, such as I/O mappings
 222  */
 223 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 224         unsigned long start, int nr_pages, int write, int force,
 225         struct page **pages, struct vm_area_struct **vmas)
 226 {
 227         int flags = 0;
 228
 229         if (write)
 230                 flags |= GUP_FLAGS_WRITE;
 231         if (force)
 232                 flags |= GUP_FLAGS_FORCE;
 233
 234         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
 235 }
 236 EXPORT_SYMBOL(get_user_pages);
 237
 238 /**
 239  * follow_pfn - look up PFN at a user virtual address
 240  * @vma: memory mapping
 241  * @address: user virtual address
 242  * @pfn: location to store found PFN
 243  *
 244  * Only IO mappings and raw PFN mappings are allowed.
 245  *
 246  * Returns zero and the pfn at @pfn on success, -ve otherwise.
 247  */
 248 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 249         unsigned long *pfn)
 250 {
 251         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 252                 return -EINVAL;
 253
 254         *pfn = address >> PAGE_SHIFT;
 255         return 0;
 256 }
 257 EXPORT_SYMBOL(follow_pfn);
 258
 259 DEFINE_RWLOCK(vmlist_lock);
 260 struct vm_struct *vmlist;
 261
 262 void vfree(const void *addr)
 263 {
 264         kfree(addr);
 265 }
 266 EXPORT_SYMBOL(vfree);
 267
 268 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 269 {
 270         /*
 271          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 272          * returns only a logical address.
 273          */
 274         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 275 }
 276 EXPORT_SYMBOL(__vmalloc);
 277
 278 void *vmalloc_user(unsigned long size)
 279 {
 280         void *ret;
 281
 282         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 283                         PAGE_KERNEL);
 284         if (ret) {
 285                 struct vm_area_struct *vma;
 286
 287                 down_write(&current->mm->mmap_sem);
 288                 vma = find_vma(current->mm, (unsigned long)ret);
 289                 if (vma)
 290                         vma->vm_flags |= VM_USERMAP;
 291                 up_write(&current->mm->mmap_sem);
 292         }
 293
 294         return ret;
 295 }
 296 EXPORT_SYMBOL(vmalloc_user);
 297
 298 struct page *vmalloc_to_page(const void *addr)
 299 {
 300         return virt_to_page(addr);
 301 }
 302 EXPORT_SYMBOL(vmalloc_to_page);
 303
 304 unsigned long vmalloc_to_pfn(const void *addr)
 305 {
 306         return page_to_pfn(virt_to_page(addr));
 307 }
 308 EXPORT_SYMBOL(vmalloc_to_pfn);
 309
 310 long vread(char *buf, char *addr, unsigned long count)
 311 {
 312         memcpy(buf, addr, count);
 313         return count;
 314 }
 315
 316 long vwrite(char *buf, char *addr, unsigned long count)
 317 {
 318         /* Don't allow overflow */
 319         if ((unsigned long) addr + count < count)
 320                 count = -(unsigned long) addr;
 321
 322         memcpy(addr, buf, count);
 323         return(count);
 324 }
 325
 326 /*
 327  *      vmalloc  -  allocate virtually continguos memory
 328  *
 329  *      @size:          allocation size
 330  *
 331  *      Allocate enough pages to cover @size from the page level
 332  *      allocator and map them into continguos kernel virtual space.
 333  *
 334  *      For tight control over page level allocator and protection flags
 335  *      use __vmalloc() instead.
 336  */
 337 void *vmalloc(unsigned long size)
 338 {
 339        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 340 }
 341 EXPORT_SYMBOL(vmalloc);
 342
 343 void *vmalloc_node(unsigned long size, int node)
 344 {
 345         return vmalloc(size);
 346 }
 347 EXPORT_SYMBOL(vmalloc_node);
 348
 349 #ifndef PAGE_KERNEL_EXEC
 350 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 351 #endif
 352
 353 /**
 354  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 355  *      @size:          allocation size
 356  *
 357  *      Kernel-internal function to allocate enough pages to cover @size
 358  *      the page level allocator and map them into contiguous and
 359  *      executable kernel virtual space.
 360  *
 361  *      For tight control over page level allocator and protection flags
 362  *      use __vmalloc() instead.
 363  */
 364
 365 void *vmalloc_exec(unsigned long size)
 366 {
 367         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 368 }
 369
 370 /**
 371  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 372  *      @size:          allocation size
 373  *
 374  *      Allocate enough 32bit PA addressable pages to cover @size from the
 375  *      page level allocator and map them into continguos kernel virtual space.
 376  */
 377 void *vmalloc_32(unsigned long size)
 378 {
 379         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 380 }
 381 EXPORT_SYMBOL(vmalloc_32);
 382
 383 /**
 384  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 385  *      @size:          allocation size
 386  *
 387  * The resulting memory area is 32bit addressable and zeroed so it can be
 388  * mapped to userspace without leaking data.
 389  *
 390  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 391  * remap_vmalloc_range() are permissible.
 392  */
 393 void *vmalloc_32_user(unsigned long size)
 394 {
 395         /*
 396          * We'll have to sort out the ZONE_DMA bits for 64-bit,
 397          * but for now this can simply use vmalloc_user() directly.
 398          */
 399         return vmalloc_user(size);
 400 }
 401 EXPORT_SYMBOL(vmalloc_32_user);
 402
 403 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 404 {
 405         BUG();
 406         return NULL;
 407 }
 408 EXPORT_SYMBOL(vmap);
 409
 410 void vunmap(const void *addr)
 411 {
 412         BUG();
 413 }
 414 EXPORT_SYMBOL(vunmap);
 415
 416 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
 417 {
 418         BUG();
 419         return NULL;
 420 }
 421 EXPORT_SYMBOL(vm_map_ram);
 422
 423 void vm_unmap_ram(const void *mem, unsigned int count)
 424 {
 425         BUG();
 426 }
 427 EXPORT_SYMBOL(vm_unmap_ram);
 428
 429 void vm_unmap_aliases(void)
 430 {
 431 }
 432 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 433
 434 /*
 435  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 436  * have one.
 437  */
 438 void  __attribute__((weak)) vmalloc_sync_all(void)
 439 {
 440 }
 441
 442 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 443                    struct page *page)
 444 {
 445         return -EINVAL;
 446 }
 447 EXPORT_SYMBOL(vm_insert_page);
 448
 449 /*
 450  *  sys_brk() for the most part doesn't need the global kernel
 451  *  lock, except when an application is doing something nasty
 452  *  like trying to un-brk an area that has already been mapped
 453  *  to a regular file.  in this case, the unmapping will need
 454  *  to invoke file system routines that need the global lock.
 455  */
 456 SYSCALL_DEFINE1(brk, unsigned long, brk)
 457 {
 458         struct mm_struct *mm = current->mm;
 459
 460         if (brk < mm->start_brk || brk > mm->context.end_brk)
 461                 return mm->brk;
 462
 463         if (mm->brk == brk)
 464                 return mm->brk;
 465
 466         /*
 467          * Always allow shrinking brk
 468          */
 469         if (brk <= mm->brk) {
 470                 mm->brk = brk;
 471                 return brk;
 472         }
 473
 474         /*
 475          * Ok, looks good - let it rip.
 476          */
 477         return mm->brk = brk;
 478 }
 479
 480 /*
 481  * initialise the VMA and region record slabs
 482  */
 483 void __init mmap_init(void)
 484 {
 485         int ret;
 486
 487         ret = percpu_counter_init(&vm_committed_as, 0);
 488         VM_BUG_ON(ret);
 489         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
 490 }
 491
 492 /*
 493  * validate the region tree
 494  * - the caller must hold the region lock
 495  */
 496 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
 497 static noinline void validate_nommu_regions(void)
 498 {
 499         struct vm_region *region, *last;
 500         struct rb_node *p, *lastp;
 501
 502         lastp = rb_first(&nommu_region_tree);
 503         if (!lastp)
 504                 return;
 505
 506         last = rb_entry(lastp, struct vm_region, vm_rb);
 507         BUG_ON(unlikely(last->vm_end <= last->vm_start));
 508         BUG_ON(unlikely(last->vm_top < last->vm_end));
 509
 510         while ((p = rb_next(lastp))) {
 511                 region = rb_entry(p, struct vm_region, vm_rb);
 512                 last = rb_entry(lastp, struct vm_region, vm_rb);
 513
 514                 BUG_ON(unlikely(region->vm_end <= region->vm_start));
 515                 BUG_ON(unlikely(region->vm_top < region->vm_end));
 516                 BUG_ON(unlikely(region->vm_start < last->vm_top));
 517
 518                 lastp = p;
 519         }
 520 }
 521 #else
 522 static void validate_nommu_regions(void)
 523 {
 524 }
 525 #endif
 526
 527 /*
 528  * add a region into the global tree
 529  */
 530 static void add_nommu_region(struct vm_region *region)
 531 {
 532         struct vm_region *pregion;
 533         struct rb_node **p, *parent;
 534
 535         validate_nommu_regions();
 536
 537         parent = NULL;
 538         p = &nommu_region_tree.rb_node;
 539         while (*p) {
 540                 parent = *p;
 541                 pregion = rb_entry(parent, struct vm_region, vm_rb);
 542                 if (region->vm_start < pregion->vm_start)
 543                         p = &(*p)->rb_left;
 544                 else if (region->vm_start > pregion->vm_start)
 545                         p = &(*p)->rb_right;
 546                 else if (pregion == region)
 547                         return;
 548                 else
 549                         BUG();
 550         }
 551
 552         rb_link_node(&region->vm_rb, parent, p);
 553         rb_insert_color(&region->vm_rb, &nommu_region_tree);
 554
 555         validate_nommu_regions();
 556 }
 557
 558 /*
 559  * delete a region from the global tree
 560  */
 561 static void delete_nommu_region(struct vm_region *region)
 562 {
 563         BUG_ON(!nommu_region_tree.rb_node);
 564
 565         validate_nommu_regions();
 566         rb_erase(&region->vm_rb, &nommu_region_tree);
 567         validate_nommu_regions();
 568 }
 569
 570 /*
 571  * free a contiguous series of pages
 572  */
 573 static void free_page_series(unsigned long from, unsigned long to)
 574 {
 575         for (; from < to; from += PAGE_SIZE) {
 576                 struct page *page = virt_to_page(from);
 577
 578                 kdebug("- free %lx", from);
 579                 atomic_long_dec(&mmap_pages_allocated);
 580                 if (page_count(page) != 1)
 581                         kdebug("free page %p: refcount not one: %d",
 582                                page, page_count(page));
 583                 put_page(page);
 584         }
 585 }
 586
 587 /*
 588  * release a reference to a region
 589  * - the caller must hold the region semaphore for writing, which this releases
 590  * - the region may not have been added to the tree yet, in which case vm_top
 591  *   will equal vm_start
 592  */
 593 static void __put_nommu_region(struct vm_region *region)
 594         __releases(nommu_region_sem)
 595 {
 596         kenter("%p{%d}", region, atomic_read(&region->vm_usage));
 597
 598         BUG_ON(!nommu_region_tree.rb_node);
 599
 600         if (atomic_dec_and_test(&region->vm_usage)) {
 601                 if (region->vm_top > region->vm_start)
 602                         delete_nommu_region(region);
 603                 up_write(&nommu_region_sem);
 604
 605                 if (region->vm_file)
 606                         fput(region->vm_file);
 607
 608                 /* IO memory and memory shared directly out of the pagecache
 609                  * from ramfs/tmpfs mustn't be released here */
 610                 if (region->vm_flags & VM_MAPPED_COPY) {
 611                         kdebug("free series");
 612                         free_page_series(region->vm_start, region->vm_top);
 613                 }
 614                 kmem_cache_free(vm_region_jar, region);
 615         } else {
 616                 up_write(&nommu_region_sem);
 617         }
 618 }
 619
 620 /*
 621  * release a reference to a region
 622  */
 623 static void put_nommu_region(struct vm_region *region)
 624 {
 625         down_write(&nommu_region_sem);
 626         __put_nommu_region(region);
 627 }
 628
 629 /*
 630  * add a VMA into a process's mm_struct in the appropriate place in the list
 631  * and tree and add to the address space's page tree also if not an anonymous
 632  * page
 633  * - should be called with mm->mmap_sem held writelocked
 634  */
 635 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 636 {
 637         struct vm_area_struct *pvma, **pp;
 638         struct address_space *mapping;
 639         struct rb_node **p, *parent;
 640
 641         kenter(",%p", vma);
 642
 643         BUG_ON(!vma->vm_region);
 644
 645         mm->map_count++;
 646         vma->vm_mm = mm;
 647
 648         /* add the VMA to the mapping */
 649         if (vma->vm_file) {
 650                 mapping = vma->vm_file->f_mapping;
 651
 652                 flush_dcache_mmap_lock(mapping);
 653                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 654                 flush_dcache_mmap_unlock(mapping);
 655         }
 656
 657         /* add the VMA to the tree */
 658         parent = NULL;
 659         p = &mm->mm_rb.rb_node;
 660         while (*p) {
 661                 parent = *p;
 662                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 663
 664                 /* sort by: start addr, end addr, VMA struct addr in that order
 665                  * (the latter is necessary as we may get identical VMAs) */
 666                 if (vma->vm_start < pvma->vm_start)
 667                         p = &(*p)->rb_left;
 668                 else if (vma->vm_start > pvma->vm_start)
 669                         p = &(*p)->rb_right;
 670                 else if (vma->vm_end < pvma->vm_end)
 671                         p = &(*p)->rb_left;
 672                 else if (vma->vm_end > pvma->vm_end)
 673                         p = &(*p)->rb_right;
 674                 else if (vma < pvma)
 675                         p = &(*p)->rb_left;
 676                 else if (vma > pvma)
 677                         p = &(*p)->rb_right;
 678                 else
 679                         BUG();
 680         }
 681
 682         rb_link_node(&vma->vm_rb, parent, p);
 683         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 684
 685         /* add VMA to the VMA list also */
 686         for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
 687                 if (pvma->vm_start > vma->vm_start)
 688                         break;
 689                 if (pvma->vm_start < vma->vm_start)
 690                         continue;
 691                 if (pvma->vm_end < vma->vm_end)
 692                         break;
 693         }
 694
 695         vma->vm_next = *pp;
 696         *pp = vma;
 697 }
 698
 699 /*
 700  * delete a VMA from its owning mm_struct and address space
 701  */
 702 static void delete_vma_from_mm(struct vm_area_struct *vma)
 703 {
 704         struct vm_area_struct **pp;
 705         struct address_space *mapping;
 706         struct mm_struct *mm = vma->vm_mm;
 707
 708         kenter("%p", vma);
 709
 710         mm->map_count--;
 711         if (mm->mmap_cache == vma)
 712                 mm->mmap_cache = NULL;
 713
 714         /* remove the VMA from the mapping */
 715         if (vma->vm_file) {
 716                 mapping = vma->vm_file->f_mapping;
 717
 718                 flush_dcache_mmap_lock(mapping);
 719                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 720                 flush_dcache_mmap_unlock(mapping);
 721         }
 722
 723         /* remove from the MM's tree and list */
 724         rb_erase(&vma->vm_rb, &mm->mm_rb);
 725         for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
 726                 if (*pp == vma) {
 727                         *pp = vma->vm_next;
 728                         break;
 729                 }
 730         }
 731
 732         vma->vm_mm = NULL;
 733 }
 734
 735 /*
 736  * destroy a VMA record
 737  */
 738 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 739 {
 740         kenter("%p", vma);
 741         if (vma->vm_ops && vma->vm_ops->close)
 742                 vma->vm_ops->close(vma);
 743         if (vma->vm_file) {
 744                 fput(vma->vm_file);
 745                 if (vma->vm_flags & VM_EXECUTABLE)
 746                         removed_exe_file_vma(mm);
 747         }
 748         put_nommu_region(vma->vm_region);
 749         kmem_cache_free(vm_area_cachep, vma);
 750 }
 751
 752 /*
 753  * look up the first VMA in which addr resides, NULL if none
 754  * - should be called with mm->mmap_sem at least held readlocked
 755  */
 756 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 757 {
 758         struct vm_area_struct *vma;
 759         struct rb_node *n = mm->mm_rb.rb_node;
 760
 761         /* check the cache first */
 762         vma = mm->mmap_cache;
 763         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
 764                 return vma;
 765
 766         /* trawl the tree (there may be multiple mappings in which addr
 767          * resides) */
 768         for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
 769                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 770                 if (vma->vm_start > addr)
 771                         return NULL;
 772                 if (vma->vm_end > addr) {
 773                         mm->mmap_cache = vma;
 774                         return vma;
 775                 }
 776         }
 777
 778         return NULL;
 779 }
 780 EXPORT_SYMBOL(find_vma);
 781
 782 /*
 783  * find a VMA
 784  * - we don't extend stack VMAs under NOMMU conditions
 785  */
 786 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 787 {
 788         return find_vma(mm, addr);
 789 }
 790
 791 /*
 792  * expand a stack to a given address
 793  * - not supported under NOMMU conditions
 794  */
 795 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 796 {
 797         return -ENOMEM;
 798 }
 799
 800 /*
 801  * look up the first VMA exactly that exactly matches addr
 802  * - should be called with mm->mmap_sem at least held readlocked
 803  */
 804 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 805                                              unsigned long addr,
 806                                              unsigned long len)
 807 {
 808         struct vm_area_struct *vma;
 809         struct rb_node *n = mm->mm_rb.rb_node;
 810         unsigned long end = addr + len;
 811
 812         /* check the cache first */
 813         vma = mm->mmap_cache;
 814         if (vma && vma->vm_start == addr && vma->vm_end == end)
 815                 return vma;
 816
 817         /* trawl the tree (there may be multiple mappings in which addr
 818          * resides) */
 819         for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
 820                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 821                 if (vma->vm_start < addr)
 822                         continue;
 823                 if (vma->vm_start > addr)
 824                         return NULL;
 825                 if (vma->vm_end == end) {
 826                         mm->mmap_cache = vma;
 827                         return vma;
 828                 }
 829         }
 830
 831         return NULL;
 832 }
 833
 834 /*
 835  * determine whether a mapping should be permitted and, if so, what sort of
 836  * mapping we're capable of supporting
 837  */
 838 static int validate_mmap_request(struct file *file,
 839                                  unsigned long addr,
 840                                  unsigned long len,
 841                                  unsigned long prot,
 842                                  unsigned long flags,
 843                                  unsigned long pgoff,
 844                                  unsigned long *_capabilities)
 845 {
 846         unsigned long capabilities, rlen;
 847         unsigned long reqprot = prot;
 848         int ret;
 849
 850         /* do the simple checks first */
 851         if (flags & MAP_FIXED || addr) {
 852                 printk(KERN_DEBUG
 853                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 854                        current->pid);
 855                 return -EINVAL;
 856         }
 857
 858         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 859             (flags & MAP_TYPE) != MAP_SHARED)
 860                 return -EINVAL;
 861
 862         if (!len)
 863                 return -EINVAL;
 864
 865         /* Careful about overflows.. */
 866         rlen = PAGE_ALIGN(len);
 867         if (!rlen || rlen > TASK_SIZE)
 868                 return -ENOMEM;
 869
 870         /* offset overflow? */
 871         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
 872                 return -EOVERFLOW;
 873
 874         if (file) {
 875                 /* validate file mapping requests */
 876                 struct address_space *mapping;
 877
 878                 /* files must support mmap */
 879                 if (!file->f_op || !file->f_op->mmap)
 880                         return -ENODEV;
 881
 882                 /* work out if what we've got could possibly be shared
 883                  * - we support chardevs that provide their own "memory"
 884                  * - we support files/blockdevs that are memory backed
 885                  */
 886                 mapping = file->f_mapping;
 887                 if (!mapping)
 888                         mapping = file->f_path.dentry->d_inode->i_mapping;
 889
 890                 capabilities = 0;
 891                 if (mapping && mapping->backing_dev_info)
 892                         capabilities = mapping->backing_dev_info->capabilities;
 893
 894                 if (!capabilities) {
 895                         /* no explicit capabilities set, so assume some
 896                          * defaults */
 897                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
 898                         case S_IFREG:
 899                         case S_IFBLK:
 900                                 capabilities = BDI_CAP_MAP_COPY;
 901                                 break;
 902
 903                         case S_IFCHR:
 904                                 capabilities =
 905                                         BDI_CAP_MAP_DIRECT |
 906                                         BDI_CAP_READ_MAP |
 907                                         BDI_CAP_WRITE_MAP;
 908                                 break;
 909
 910                         default:
 911                                 return -EINVAL;
 912                         }
 913                 }
 914
 915                 /* eliminate any capabilities that we can't support on this
 916                  * device */
 917                 if (!file->f_op->get_unmapped_area)
 918                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 919                 if (!file->f_op->read)
 920                         capabilities &= ~BDI_CAP_MAP_COPY;
 921
 922                 /* The file shall have been opened with read permission. */
 923                 if (!(file->f_mode & FMODE_READ))
 924                         return -EACCES;
 925
 926                 if (flags & MAP_SHARED) {
 927                         /* do checks for writing, appending and locking */
 928                         if ((prot & PROT_WRITE) &&
 929                             !(file->f_mode & FMODE_WRITE))
 930                                 return -EACCES;
 931
 932                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
 933                             (file->f_mode & FMODE_WRITE))
 934                                 return -EACCES;
 935
 936                         if (locks_verify_locked(file->f_path.dentry->d_inode))
 937                                 return -EAGAIN;
 938
 939                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 940                                 return -ENODEV;
 941
 942                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
 943                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
 944                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
 945                             ) {
 946                                 printk("MAP_SHARED not completely supported on !MMU\n");
 947                                 return -EINVAL;
 948                         }
 949
 950                         /* we mustn't privatise shared mappings */
 951                         capabilities &= ~BDI_CAP_MAP_COPY;
 952                 }
 953                 else {
 954                         /* we're going to read the file into private memory we
 955                          * allocate */
 956                         if (!(capabilities & BDI_CAP_MAP_COPY))
 957                                 return -ENODEV;
 958
 959                         /* we don't permit a private writable mapping to be
 960                          * shared with the backing device */
 961                         if (prot & PROT_WRITE)
 962                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 963                 }
 964
 965                 /* handle executable mappings and implied executable
 966                  * mappings */
 967                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
 968                         if (prot & PROT_EXEC)
 969                                 return -EPERM;
 970                 }
 971                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 972                         /* handle implication of PROT_EXEC by PROT_READ */
 973                         if (current->personality & READ_IMPLIES_EXEC) {
 974                                 if (capabilities & BDI_CAP_EXEC_MAP)
 975                                         prot |= PROT_EXEC;
 976                         }
 977                 }
 978                 else if ((prot & PROT_READ) &&
 979                          (prot & PROT_EXEC) &&
 980                          !(capabilities & BDI_CAP_EXEC_MAP)
 981                          ) {
 982                         /* backing file is not executable, try to copy */
 983                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 984                 }
 985         }
 986         else {
 987                 /* anonymous mappings are always memory backed and can be
 988                  * privately mapped
 989                  */
 990                 capabilities = BDI_CAP_MAP_COPY;
 991
 992                 /* handle PROT_EXEC implication by PROT_READ */
 993                 if ((prot & PROT_READ) &&
 994                     (current->personality & READ_IMPLIES_EXEC))
 995                         prot |= PROT_EXEC;
 996         }
 997
 998         /* allow the security API to have its say */
 999         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1000         if (ret < 0)
1001                 return ret;
1002
1003         /* looks okay */
1004         *_capabilities = capabilities;
1005         return 0;
1006 }
1007
1008 /*
1009  * we've determined that we can make the mapping, now translate what we
1010  * now know into VMA flags
1011  */
1012 static unsigned long determine_vm_flags(struct file *file,
1013                                         unsigned long prot,
1014                                         unsigned long flags,
1015                                         unsigned long capabilities)
1016 {
1017         unsigned long vm_flags;
1018
1019         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1020         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1021         /* vm_flags |= mm->def_flags; */
1022
1023         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1024                 /* attempt to share read-only copies of mapped file chunks */
1025                 if (file && !(prot & PROT_WRITE))
1026                         vm_flags |= VM_MAYSHARE;
1027         }
1028         else {
1029                 /* overlay a shareable mapping on the backing device or inode
1030                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1031                  * romfs/cramfs */
1032                 if (flags & MAP_SHARED)
1033                         vm_flags |= VM_MAYSHARE | VM_SHARED;
1034                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
1035                         vm_flags |= VM_MAYSHARE;
1036         }
1037
1038         /* refuse to let anyone share private mappings with this process if
1039          * it's being traced - otherwise breakpoints set in it may interfere
1040          * with another untraced process
1041          */
1042         if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
1043                 vm_flags &= ~VM_MAYSHARE;
1044
1045         return vm_flags;
1046 }
1047
1048 /*
1049  * set up a shared mapping on a file (the driver or filesystem provides and
1050  * pins the storage)
1051  */
1052 static int do_mmap_shared_file(struct vm_area_struct *vma)
1053 {
1054         int ret;
1055
1056         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1057         if (ret == 0) {
1058                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1059                 return ret;
1060         }
1061         if (ret != -ENOSYS)
1062                 return ret;
1063
1064         /* getting an ENOSYS error indicates that direct mmap isn't
1065          * possible (as opposed to tried but failed) so we'll fall
1066          * through to making a private copy of the data and mapping
1067          * that if we can */
1068         return -ENODEV;
1069 }
1070
1071 /*
1072  * set up a private mapping or an anonymous shared mapping
1073  */
1074 static int do_mmap_private(struct vm_area_struct *vma,
1075                            struct vm_region *region,
1076                            unsigned long len)
1077 {
1078         struct page *pages;
1079         unsigned long total, point, n, rlen;
1080         void *base;
1081         int ret, order;
1082
1083         /* invoke the file's mapping function so that it can keep track of
1084          * shared mappings on devices or memory
1085          * - VM_MAYSHARE will be set if it may attempt to share
1086          */
1087         if (vma->vm_file) {
1088                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1089                 if (ret == 0) {
1090                         /* shouldn't return success if we're not sharing */
1091                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1092                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1093                         return ret;
1094                 }
1095                 if (ret != -ENOSYS)
1096                         return ret;
1097
1098                 /* getting an ENOSYS error indicates that direct mmap isn't
1099                  * possible (as opposed to tried but failed) so we'll try to
1100                  * make a private copy of the data and map that instead */
1101         }
1102
1103         rlen = PAGE_ALIGN(len);
1104
1105         /* allocate some memory to hold the mapping
1106          * - note that this may not return a page-aligned address if the object
1107          *   we're allocating is smaller than a page
1108          */
1109         order = get_order(rlen);
1110         kdebug("alloc order %d for %lx", order, len);
1111
1112         pages = alloc_pages(GFP_KERNEL, order);
1113         if (!pages)
1114                 goto enomem;
1115
1116         total = 1 << order;
1117         atomic_long_add(total, &mmap_pages_allocated);
1118
1119         point = rlen >> PAGE_SHIFT;
1120
1121         /* we allocated a power-of-2 sized page set, so we may want to trim off
1122          * the excess */
1123         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1124                 while (total > point) {
1125                         order = ilog2(total - point);
1126                         n = 1 << order;
1127                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1128                         atomic_long_sub(n, &mmap_pages_allocated);
1129                         total -= n;
1130                         set_page_refcounted(pages + total);
1131                         __free_pages(pages + total, order);
1132                 }
1133         }
1134
1135         for (point = 1; point < total; point++)
1136                 set_page_refcounted(&pages[point]);
1137
1138         base = page_address(pages);
1139         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1140         region->vm_start = (unsigned long) base;
1141         region->vm_end   = region->vm_start + rlen;
1142         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1143
1144         vma->vm_start = region->vm_start;
1145         vma->vm_end   = region->vm_start + len;
1146
1147         if (vma->vm_file) {
1148                 /* read the contents of a file into the copy */
1149                 mm_segment_t old_fs;
1150                 loff_t fpos;
1151
1152                 fpos = vma->vm_pgoff;
1153                 fpos <<= PAGE_SHIFT;
1154
1155                 old_fs = get_fs();
1156                 set_fs(KERNEL_DS);
1157                 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
1158                 set_fs(old_fs);
1159
1160                 if (ret < 0)
1161                         goto error_free;
1162
1163                 /* clear the last little bit */
1164                 if (ret < rlen)
1165                         memset(base + ret, 0, rlen - ret);
1166
1167         } else {
1168                 /* if it's an anonymous mapping, then just clear it */
1169                 memset(base, 0, rlen);
1170         }
1171
1172         return 0;
1173
1174 error_free:
1175         free_page_series(region->vm_start, region->vm_end);
1176         region->vm_start = vma->vm_start = 0;
1177         region->vm_end   = vma->vm_end = 0;
1178         region->vm_top   = 0;
1179         return ret;
1180
1181 enomem:
1182         printk("Allocation of length %lu from process %d (%s) failed\n",
1183                len, current->pid, current->comm);
1184         show_free_areas();
1185         return -ENOMEM;
1186 }
1187
1188 /*
1189  * handle mapping creation for uClinux
1190  */
1191 unsigned long do_mmap_pgoff(struct file *file,
1192                             unsigned long addr,
1193                             unsigned long len,
1194                             unsigned long prot,
1195                             unsigned long flags,
1196                             unsigned long pgoff)
1197 {
1198         struct vm_area_struct *vma;
1199         struct vm_region *region;
1200         struct rb_node *rb;
1201         unsigned long capabilities, vm_flags, result;
1202         int ret;
1203
1204         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1205
1206         if (!(flags & MAP_FIXED))
1207                 addr = round_hint_to_min(addr);
1208
1209         /* decide whether we should attempt the mapping, and if so what sort of
1210          * mapping */
1211         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1212                                     &capabilities);
1213         if (ret < 0) {
1214                 kleave(" = %d [val]", ret);
1215                 return ret;
1216         }
1217
1218         /* we've determined that we can make the mapping, now translate what we
1219          * now know into VMA flags */
1220         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1221
1222         /* we're going to need to record the mapping */
1223         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1224         if (!region)
1225                 goto error_getting_region;
1226
1227         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1228         if (!vma)
1229                 goto error_getting_vma;
1230
1231         atomic_set(&region->vm_usage, 1);
1232         region->vm_flags = vm_flags;
1233         region->vm_pgoff = pgoff;
1234
1235         INIT_LIST_HEAD(&vma->anon_vma_node);
1236         vma->vm_flags = vm_flags;
1237         vma->vm_pgoff = pgoff;
1238
1239         if (file) {
1240                 region->vm_file = file;
1241                 get_file(file);
1242                 vma->vm_file = file;
1243                 get_file(file);
1244                 if (vm_flags & VM_EXECUTABLE) {
1245                         added_exe_file_vma(current->mm);
1246                         vma->vm_mm = current->mm;
1247                 }
1248         }
1249
1250         down_write(&nommu_region_sem);
1251
1252         /* if we want to share, we need to check for regions created by other
1253          * mmap() calls that overlap with our proposed mapping
1254          * - we can only share with a superset match on most regular files
1255          * - shared mappings on character devices and memory backed files are
1256          *   permitted to overlap inexactly as far as we are concerned for in
1257          *   these cases, sharing is handled in the driver or filesystem rather
1258          *   than here
1259          */
1260         if (vm_flags & VM_MAYSHARE) {
1261                 struct vm_region *pregion;
1262                 unsigned long pglen, rpglen, pgend, rpgend, start;
1263
1264                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1265                 pgend = pgoff + pglen;
1266
1267                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1268                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1269
1270                         if (!(pregion->vm_flags & VM_MAYSHARE))
1271                                 continue;
1272
1273                         /* search for overlapping mappings on the same file */
1274                         if (pregion->vm_file->f_path.dentry->d_inode !=
1275                             file->f_path.dentry->d_inode)
1276                                 continue;
1277
1278                         if (pregion->vm_pgoff >= pgend)
1279                                 continue;
1280
1281                         rpglen = pregion->vm_end - pregion->vm_start;
1282                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1283                         rpgend = pregion->vm_pgoff + rpglen;
1284                         if (pgoff >= rpgend)
1285                                 continue;
1286
1287                         /* handle inexactly overlapping matches between
1288                          * mappings */
1289                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1290                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1291                                 /* new mapping is not a subset of the region */
1292                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1293                                         goto sharing_violation;
1294                                 continue;
1295                         }
1296
1297                         /* we've found a region we can share */
1298                         atomic_inc(&pregion->vm_usage);
1299                         vma->vm_region = pregion;
1300                         start = pregion->vm_start;
1301                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1302                         vma->vm_start = start;
1303                         vma->vm_end = start + len;
1304
1305                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1306                                 kdebug("share copy");
1307                                 vma->vm_flags |= VM_MAPPED_COPY;
1308                         } else {
1309                                 kdebug("share mmap");
1310                                 ret = do_mmap_shared_file(vma);
1311                                 if (ret < 0) {
1312                                         vma->vm_region = NULL;
1313                                         vma->vm_start = 0;
1314                                         vma->vm_end = 0;
1315                                         atomic_dec(&pregion->vm_usage);
1316                                         pregion = NULL;
1317                                         goto error_just_free;
1318                                 }
1319                         }
1320                         fput(region->vm_file);
1321                         kmem_cache_free(vm_region_jar, region);
1322                         region = pregion;
1323                         result = start;
1324                         goto share;
1325                 }
1326
1327                 /* obtain the address at which to make a shared mapping
1328                  * - this is the hook for quasi-memory character devices to
1329                  *   tell us the location of a shared mapping
1330                  */
1331                 if (file && file->f_op->get_unmapped_area) {
1332                         addr = file->f_op->get_unmapped_area(file, addr, len,
1333                                                              pgoff, flags);
1334                         if (IS_ERR((void *) addr)) {
1335                                 ret = addr;
1336                                 if (ret != (unsigned long) -ENOSYS)
1337                                         goto error_just_free;
1338
1339                                 /* the driver refused to tell us where to site
1340                                  * the mapping so we'll have to attempt to copy
1341                                  * it */
1342                                 ret = (unsigned long) -ENODEV;
1343                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1344                                         goto error_just_free;
1345
1346                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1347                         } else {
1348                                 vma->vm_start = region->vm_start = addr;
1349                                 vma->vm_end = region->vm_end = addr + len;
1350                         }
1351                 }
1352         }
1353
1354         vma->vm_region = region;
1355         add_nommu_region(region);
1356
1357         /* set up the mapping */
1358         if (file && vma->vm_flags & VM_SHARED)
1359                 ret = do_mmap_shared_file(vma);
1360         else
1361                 ret = do_mmap_private(vma, region, len);
1362         if (ret < 0)
1363                 goto error_put_region;
1364
1365         /* okay... we have a mapping; now we have to register it */
1366         result = vma->vm_start;
1367
1368         current->mm->total_vm += len >> PAGE_SHIFT;
1369
1370 share:
1371         add_vma_to_mm(current->mm, vma);
1372
1373         up_write(&nommu_region_sem);
1374
1375         if (prot & PROT_EXEC)
1376                 flush_icache_range(result, result + len);
1377
1378         kleave(" = %lx", result);
1379         return result;
1380
1381 error_put_region:
1382         __put_nommu_region(region);
1383         if (vma) {
1384                 if (vma->vm_file) {
1385                         fput(vma->vm_file);
1386                         if (vma->vm_flags & VM_EXECUTABLE)
1387                                 removed_exe_file_vma(vma->vm_mm);
1388                 }
1389                 kmem_cache_free(vm_area_cachep, vma);
1390         }
1391         kleave(" = %d [pr]", ret);
1392         return ret;
1393
1394 error_just_free:
1395         up_write(&nommu_region_sem);
1396 error:
1397         fput(region->vm_file);
1398         kmem_cache_free(vm_region_jar, region);
1399         fput(vma->vm_file);
1400         if (vma->vm_flags & VM_EXECUTABLE)
1401                 removed_exe_file_vma(vma->vm_mm);
1402         kmem_cache_free(vm_area_cachep, vma);
1403         kleave(" = %d", ret);
1404         return ret;
1405
1406 sharing_violation:
1407         up_write(&nommu_region_sem);
1408         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1409         ret = -EINVAL;
1410         goto error;
1411
1412 error_getting_vma:
1413         kmem_cache_free(vm_region_jar, region);
1414         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1415                " from process %d failed\n",
1416                len, current->pid);
1417         show_free_areas();
1418         return -ENOMEM;
1419
1420 error_getting_region:
1421         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1422                " from process %d failed\n",
1423                len, current->pid);
1424         show_free_areas();
1425         return -ENOMEM;
1426 }
1427 EXPORT_SYMBOL(do_mmap_pgoff);
1428
1429 /*
1430  * split a vma into two pieces at address 'addr', a new vma is allocated either
1431  * for the first part or the tail.
1432  */
1433 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1434               unsigned long addr, int new_below)
1435 {
1436         struct vm_area_struct *new;
1437         struct vm_region *region;
1438         unsigned long npages;
1439
1440         kenter("");
1441
1442         /* we're only permitted to split anonymous regions that have a single
1443          * owner */
1444         if (vma->vm_file ||
1445             atomic_read(&vma->vm_region->vm_usage) != 1)
1446                 return -ENOMEM;
1447
1448         if (mm->map_count >= sysctl_max_map_count)
1449                 return -ENOMEM;
1450
1451         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1452         if (!region)
1453                 return -ENOMEM;
1454
1455         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1456         if (!new) {
1457                 kmem_cache_free(vm_region_jar, region);
1458                 return -ENOMEM;
1459         }
1460
1461         /* most fields are the same, copy all, and then fixup */
1462         *new = *vma;
1463         *region = *vma->vm_region;
1464         new->vm_region = region;
1465
1466         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1467
1468         if (new_below) {
1469                 region->vm_top = region->vm_end = new->vm_end = addr;
1470         } else {
1471                 region->vm_start = new->vm_start = addr;
1472                 region->vm_pgoff = new->vm_pgoff += npages;
1473         }
1474
1475         if (new->vm_ops && new->vm_ops->open)
1476                 new->vm_ops->open(new);
1477
1478         delete_vma_from_mm(vma);
1479         down_write(&nommu_region_sem);
1480         delete_nommu_region(vma->vm_region);
1481         if (new_below) {
1482                 vma->vm_region->vm_start = vma->vm_start = addr;
1483                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1484         } else {
1485                 vma->vm_region->vm_end = vma->vm_end = addr;
1486                 vma->vm_region->vm_top = addr;
1487         }
1488         add_nommu_region(vma->vm_region);
1489         add_nommu_region(new->vm_region);
1490         up_write(&nommu_region_sem);
1491         add_vma_to_mm(mm, vma);
1492         add_vma_to_mm(mm, new);
1493         return 0;
1494 }
1495
1496 /*
1497  * shrink a VMA by removing the specified chunk from either the beginning or
1498  * the end
1499  */
1500 static int shrink_vma(struct mm_struct *mm,
1501                       struct vm_area_struct *vma,
1502                       unsigned long from, unsigned long to)
1503 {
1504         struct vm_region *region;
1505
1506         kenter("");
1507
1508         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1509          * and list */
1510         delete_vma_from_mm(vma);
1511         if (from > vma->vm_start)
1512                 vma->vm_end = from;
1513         else
1514                 vma->vm_start = to;
1515         add_vma_to_mm(mm, vma);
1516
1517         /* cut the backing region down to size */
1518         region = vma->vm_region;
1519         BUG_ON(atomic_read(&region->vm_usage) != 1);
1520
1521         down_write(&nommu_region_sem);
1522         delete_nommu_region(region);
1523         if (from > region->vm_start) {
1524                 to = region->vm_top;
1525                 region->vm_top = region->vm_end = from;
1526         } else {
1527                 region->vm_start = to;
1528         }
1529         add_nommu_region(region);
1530         up_write(&nommu_region_sem);
1531
1532         free_page_series(from, to);
1533         return 0;
1534 }
1535
1536 /*
1537  * release a mapping
1538  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1539  *   VMA, though it need not cover the whole VMA
1540  */
1541 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1542 {
1543         struct vm_area_struct *vma;
1544         struct rb_node *rb;
1545         unsigned long end = start + len;
1546         int ret;
1547
1548         kenter(",%lx,%zx", start, len);
1549
1550         if (len == 0)
1551                 return -EINVAL;
1552
1553         /* find the first potentially overlapping VMA */
1554         vma = find_vma(mm, start);
1555         if (!vma) {
1556                 static int limit = 0;
1557                 if (limit < 5) {
1558                         printk(KERN_WARNING
1559                                "munmap of memory not mmapped by process %d"
1560                                " (%s): 0x%lx-0x%lx\n",
1561                                current->pid, current->comm,
1562                                start, start + len - 1);
1563                         limit++;
1564                 }
1565                 return -EINVAL;
1566         }
1567
1568         /* we're allowed to split an anonymous VMA but not a file-backed one */
1569         if (vma->vm_file) {
1570                 do {
1571                         if (start > vma->vm_start) {
1572                                 kleave(" = -EINVAL [miss]");
1573                                 return -EINVAL;
1574                         }
1575                         if (end == vma->vm_end)
1576                                 goto erase_whole_vma;
1577                         rb = rb_next(&vma->vm_rb);
1578                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
1579                 } while (rb);
1580                 kleave(" = -EINVAL [split file]");
1581                 return -EINVAL;
1582         } else {
1583                 /* the chunk must be a subset of the VMA found */
1584                 if (start == vma->vm_start && end == vma->vm_end)
1585                         goto erase_whole_vma;
1586                 if (start < vma->vm_start || end > vma->vm_end) {
1587                         kleave(" = -EINVAL [superset]");
1588                         return -EINVAL;
1589                 }
1590                 if (start & ~PAGE_MASK) {
1591                         kleave(" = -EINVAL [unaligned start]");
1592                         return -EINVAL;
1593                 }
1594                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1595                         kleave(" = -EINVAL [unaligned split]");
1596                         return -EINVAL;
1597                 }
1598                 if (start != vma->vm_start && end != vma->vm_end) {
1599                         ret = split_vma(mm, vma, start, 1);
1600                         if (ret < 0) {
1601                                 kleave(" = %d [split]", ret);
1602                                 return ret;
1603                         }
1604                 }
1605                 return shrink_vma(mm, vma, start, end);
1606         }
1607
1608 erase_whole_vma:
1609         delete_vma_from_mm(vma);
1610         delete_vma(mm, vma);
1611         kleave(" = 0");
1612         return 0;
1613 }
1614 EXPORT_SYMBOL(do_munmap);
1615
1616 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1617 {
1618         int ret;
1619         struct mm_struct *mm = current->mm;
1620
1621         down_write(&mm->mmap_sem);
1622         ret = do_munmap(mm, addr, len);
1623         up_write(&mm->mmap_sem);
1624         return ret;
1625 }
1626
1627 /*
1628  * release all the mappings made in a process's VM space
1629  */
1630 void exit_mmap(struct mm_struct *mm)
1631 {
1632         struct vm_area_struct *vma;
1633
1634         if (!mm)
1635                 return;
1636
1637         kenter("");
1638
1639         mm->total_vm = 0;
1640
1641         while ((vma = mm->mmap)) {
1642                 mm->mmap = vma->vm_next;
1643                 delete_vma_from_mm(vma);
1644                 delete_vma(mm, vma);
1645         }
1646
1647         kleave("");
1648 }
1649
1650 unsigned long do_brk(unsigned long addr, unsigned long len)
1651 {
1652         return -ENOMEM;
1653 }
1654
1655 /*
1656  * expand (or shrink) an existing mapping, potentially moving it at the same
1657  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1658  *
1659  * under NOMMU conditions, we only permit changing a mapping's size, and only
1660  * as long as it stays within the region allocated by do_mmap_private() and the
1661  * block is not shareable
1662  *
1663  * MREMAP_FIXED is not supported under NOMMU conditions
1664  */
1665 unsigned long do_mremap(unsigned long addr,
1666                         unsigned long old_len, unsigned long new_len,
1667                         unsigned long flags, unsigned long new_addr)
1668 {
1669         struct vm_area_struct *vma;
1670
1671         /* insanity checks first */
1672         if (old_len == 0 || new_len == 0)
1673                 return (unsigned long) -EINVAL;
1674
1675         if (addr & ~PAGE_MASK)
1676                 return -EINVAL;
1677
1678         if (flags & MREMAP_FIXED && new_addr != addr)
1679                 return (unsigned long) -EINVAL;
1680
1681         vma = find_vma_exact(current->mm, addr, old_len);
1682         if (!vma)
1683                 return (unsigned long) -EINVAL;
1684
1685         if (vma->vm_end != vma->vm_start + old_len)
1686                 return (unsigned long) -EFAULT;
1687
1688         if (vma->vm_flags & VM_MAYSHARE)
1689                 return (unsigned long) -EPERM;
1690
1691         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1692                 return (unsigned long) -ENOMEM;
1693
1694         /* all checks complete - do it */
1695         vma->vm_end = vma->vm_start + new_len;
1696         return vma->vm_start;
1697 }
1698 EXPORT_SYMBOL(do_mremap);
1699
1700 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1701                 unsigned long, new_len, unsigned long, flags,
1702                 unsigned long, new_addr)
1703 {
1704         unsigned long ret;
1705
1706         down_write(&current->mm->mmap_sem);
1707         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1708         up_write(&current->mm->mmap_sem);
1709         return ret;
1710 }
1711
1712 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1713                         unsigned int foll_flags)
1714 {
1715         return NULL;
1716 }
1717
1718 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1719                 unsigned long to, unsigned long size, pgprot_t prot)
1720 {
1721         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1722         return 0;
1723 }
1724 EXPORT_SYMBOL(remap_pfn_range);
1725
1726 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1727                         unsigned long pgoff)
1728 {
1729         unsigned int size = vma->vm_end - vma->vm_start;
1730
1731         if (!(vma->vm_flags & VM_USERMAP))
1732                 return -EINVAL;
1733
1734         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1735         vma->vm_end = vma->vm_start + size;
1736
1737         return 0;
1738 }
1739 EXPORT_SYMBOL(remap_vmalloc_range);
1740
1741 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1742 {
1743 }
1744
1745 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1746         unsigned long len, unsigned long pgoff, unsigned long flags)
1747 {
1748         return -ENOMEM;
1749 }
1750
1751 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1752 {
1753 }
1754
1755 void unmap_mapping_range(struct address_space *mapping,
1756                          loff_t const holebegin, loff_t const holelen,
1757                          int even_cows)
1758 {
1759 }
1760 EXPORT_SYMBOL(unmap_mapping_range);
1761
1762 /*
1763  * ask for an unmapped area at which to create a mapping on a file
1764  */
1765 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1766                                 unsigned long len, unsigned long pgoff,
1767                                 unsigned long flags)
1768 {
1769         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1770                                   unsigned long, unsigned long);
1771
1772         get_area = current->mm->get_unmapped_area;
1773         if (file && file->f_op && file->f_op->get_unmapped_area)
1774                 get_area = file->f_op->get_unmapped_area;
1775
1776         if (!get_area)
1777                 return -ENOSYS;
1778
1779         return get_area(file, addr, len, pgoff, flags);
1780 }
1781 EXPORT_SYMBOL(get_unmapped_area);
1782
1783 /*
1784  * Check that a process has enough memory to allocate a new virtual
1785  * mapping. 0 means there is enough memory for the allocation to
1786  * succeed and -ENOMEM implies there is not.
1787  *
1788  * We currently support three overcommit policies, which are set via the
1789  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1790  *
1791  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1792  * Additional code 2002 Jul 20 by Robert Love.
1793  *
1794  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1795  *
1796  * Note this is a helper function intended to be used by LSMs which
1797  * wish to use this logic.
1798  */
1799 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1800 {
1801         unsigned long free, allowed;
1802
1803         vm_acct_memory(pages);
1804
1805         /*
1806          * Sometimes we want to use more memory than we have
1807          */
1808         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1809                 return 0;
1810
1811         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1812                 unsigned long n;
1813
1814                 free = global_page_state(NR_FILE_PAGES);
1815                 free += nr_swap_pages;
1816
1817                 /*
1818                  * Any slabs which are created with the
1819                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1820                  * which are reclaimable, under pressure.  The dentry
1821                  * cache and most inode caches should fall into this
1822                  */
1823                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1824
1825                 /*
1826                  * Leave the last 3% for root
1827                  */
1828                 if (!cap_sys_admin)
1829                         free -= free / 32;
1830
1831                 if (free > pages)
1832                         return 0;
1833
1834                 /*
1835                  * nr_free_pages() is very expensive on large systems,
1836                  * only call if we're about to fail.
1837                  */
1838                 n = nr_free_pages();
1839
1840                 /*
1841                  * Leave reserved pages. The pages are not for anonymous pages.
1842                  */
1843                 if (n <= totalreserve_pages)
1844                         goto error;
1845                 else
1846                         n -= totalreserve_pages;
1847
1848                 /*
1849                  * Leave the last 3% for root
1850                  */
1851                 if (!cap_sys_admin)
1852                         n -= n / 32;
1853                 free += n;
1854
1855                 if (free > pages)
1856                         return 0;
1857
1858                 goto error;
1859         }
1860
1861         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1862         /*
1863          * Leave the last 3% for root
1864          */
1865         if (!cap_sys_admin)
1866                 allowed -= allowed / 32;
1867         allowed += total_swap_pages;
1868
1869         /* Don't let a single process grow too big:
1870            leave 3% of the size of this process for other processes */
1871         if (mm)
1872                 allowed -= mm->total_vm / 32;
1873
1874         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1875                 return 0;
1876
1877 error:
1878         vm_unacct_memory(pages);
1879
1880         return -ENOMEM;
1881 }
1882
1883 int in_gate_area_no_task(unsigned long addr)
1884 {
1885         return 0;
1886 }
1887
1888 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1889 {
1890         BUG();
1891         return 0;
1892 }
1893 EXPORT_SYMBOL(filemap_fault);
1894
1895 /*
1896  * Access another process' address space.
1897  * - source/target buffer must be kernel space
1898  */
1899 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1900 {
1901         struct vm_area_struct *vma;
1902         struct mm_struct *mm;
1903
1904         if (addr + len < addr)
1905                 return 0;
1906
1907         mm = get_task_mm(tsk);
1908         if (!mm)
1909                 return 0;
1910
1911         down_read(&mm->mmap_sem);
1912
1913         /* the access must start within one of the target process's mappings */
1914         vma = find_vma(mm, addr);
1915         if (vma) {
1916                 /* don't overrun this mapping */
1917                 if (addr + len >= vma->vm_end)
1918                         len = vma->vm_end - addr;
1919
1920                 /* only read or write mappings where it is permitted */
1921                 if (write && vma->vm_flags & VM_MAYWRITE)
1922                         len -= copy_to_user((void *) addr, buf, len);
1923                 else if (!write && vma->vm_flags & VM_MAYREAD)
1924                         len -= copy_from_user(buf, (void *) addr, len);
1925                 else
1926                         len = 0;
1927         } else {
1928                 len = 0;
1929         }
1930
1931         up_read(&mm->mmap_sem);
1932         mmput(mm);
1933         return len;
1934 }