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