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