mm/nommu.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/mm/nommu.c
   4  *
   5  *  Replacement code for mm functions to support CPU's that don't
   6  *  have any form of memory management unit (thus no virtual memory).
   7  *
   8  *  See Documentation/nommu-mmap.txt
   9  *
  10  *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
  11  *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
  12  *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
  13  *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
  14  *  Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/export.h>
  20 #include <linux/mm.h>
  21 #include <linux/sched/mm.h>
  22 #include <linux/vmacache.h>
  23 #include <linux/mman.h>
  24 #include <linux/swap.h>
  25 #include <linux/file.h>
  26 #include <linux/highmem.h>
  27 #include <linux/pagemap.h>
  28 #include <linux/slab.h>
  29 #include <linux/vmalloc.h>
  30 #include <linux/blkdev.h>
  31 #include <linux/backing-dev.h>
  32 #include <linux/compiler.h>
  33 #include <linux/mount.h>
  34 #include <linux/personality.h>
  35 #include <linux/security.h>
  36 #include <linux/syscalls.h>
  37 #include <linux/audit.h>
  38 #include <linux/printk.h>
  39
  40 #include <linux/uaccess.h>
  41 #include <asm/tlb.h>
  42 #include <asm/tlbflush.h>
  43 #include <asm/mmu_context.h>
  44 #include "internal.h"
  45
  46 void *high_memory;
  47 EXPORT_SYMBOL(high_memory);
  48 struct page *mem_map;
  49 unsigned long max_mapnr;
  50 EXPORT_SYMBOL(max_mapnr);
  51 unsigned long highest_memmap_pfn;
  52 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
  53 int heap_stack_gap = 0;
  54
  55 atomic_long_t mmap_pages_allocated;
  56
  57 EXPORT_SYMBOL(mem_map);
  58
  59 /* list of mapped, potentially shareable regions */
  60 static struct kmem_cache *vm_region_jar;
  61 struct rb_root nommu_region_tree = RB_ROOT;
  62 DECLARE_RWSEM(nommu_region_sem);
  63
  64 const struct vm_operations_struct generic_file_vm_ops = {
  65 };
  66
  67 /*
  68  * Return the total memory allocated for this pointer, not
  69  * just what the caller asked for.
  70  *
  71  * Doesn't have to be accurate, i.e. may have races.
  72  */
  73 unsigned int kobjsize(const void *objp)
  74 {
  75         struct page *page;
  76
  77         /*
  78          * If the object we have should not have ksize performed on it,
  79          * return size of 0
  80          */
  81         if (!objp || !virt_addr_valid(objp))
  82                 return 0;
  83
  84         page = virt_to_head_page(objp);
  85
  86         /*
  87          * If the allocator sets PageSlab, we know the pointer came from
  88          * kmalloc().
  89          */
  90         if (PageSlab(page))
  91                 return ksize(objp);
  92
  93         /*
  94          * If it's not a compound page, see if we have a matching VMA
  95          * region. This test is intentionally done in reverse order,
  96          * so if there's no VMA, we still fall through and hand back
  97          * PAGE_SIZE for 0-order pages.
  98          */
  99         if (!PageCompound(page)) {
 100                 struct vm_area_struct *vma;
 101
 102                 vma = find_vma(current->mm, (unsigned long)objp);
 103                 if (vma)
 104                         return vma->vm_end - vma->vm_start;
 105         }
 106
 107         /*
 108          * The ksize() function is only guaranteed to work for pointers
 109          * returned by kmalloc(). So handle arbitrary pointers here.
 110          */
 111         return PAGE_SIZE << compound_order(page);
 112 }
 113
 114 /**
 115  * follow_pfn - look up PFN at a user virtual address
 116  * @vma: memory mapping
 117  * @address: user virtual address
 118  * @pfn: location to store found PFN
 119  *
 120  * Only IO mappings and raw PFN mappings are allowed.
 121  *
 122  * Returns zero and the pfn at @pfn on success, -ve otherwise.
 123  */
 124 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 125         unsigned long *pfn)
 126 {
 127         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 128                 return -EINVAL;
 129
 130         *pfn = address >> PAGE_SHIFT;
 131         return 0;
 132 }
 133 EXPORT_SYMBOL(follow_pfn);
 134
 135 LIST_HEAD(vmap_area_list);
 136
 137 void vfree(const void *addr)
 138 {
 139         kfree(addr);
 140 }
 141 EXPORT_SYMBOL(vfree);
 142
 143 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 144 {
 145         /*
 146          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 147          * returns only a logical address.
 148          */
 149         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 150 }
 151 EXPORT_SYMBOL(__vmalloc);
 152
 153 void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags)
 154 {
 155         return __vmalloc(size, flags, PAGE_KERNEL);
 156 }
 157
 158 void *vmalloc_user(unsigned long size)
 159 {
 160         void *ret;
 161
 162         ret = __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
 163         if (ret) {
 164                 struct vm_area_struct *vma;
 165
 166                 down_write(&current->mm->mmap_sem);
 167                 vma = find_vma(current->mm, (unsigned long)ret);
 168                 if (vma)
 169                         vma->vm_flags |= VM_USERMAP;
 170                 up_write(&current->mm->mmap_sem);
 171         }
 172
 173         return ret;
 174 }
 175 EXPORT_SYMBOL(vmalloc_user);
 176
 177 struct page *vmalloc_to_page(const void *addr)
 178 {
 179         return virt_to_page(addr);
 180 }
 181 EXPORT_SYMBOL(vmalloc_to_page);
 182
 183 unsigned long vmalloc_to_pfn(const void *addr)
 184 {
 185         return page_to_pfn(virt_to_page(addr));
 186 }
 187 EXPORT_SYMBOL(vmalloc_to_pfn);
 188
 189 long vread(char *buf, char *addr, unsigned long count)
 190 {
 191         /* Don't allow overflow */
 192         if ((unsigned long) buf + count < count)
 193                 count = -(unsigned long) buf;
 194
 195         memcpy(buf, addr, count);
 196         return count;
 197 }
 198
 199 long vwrite(char *buf, char *addr, unsigned long count)
 200 {
 201         /* Don't allow overflow */
 202         if ((unsigned long) addr + count < count)
 203                 count = -(unsigned long) addr;
 204
 205         memcpy(addr, buf, count);
 206         return count;
 207 }
 208
 209 /*
 210  *      vmalloc  -  allocate virtually contiguous memory
 211  *
 212  *      @size:          allocation size
 213  *
 214  *      Allocate enough pages to cover @size from the page level
 215  *      allocator and map them into contiguous kernel virtual space.
 216  *
 217  *      For tight control over page level allocator and protection flags
 218  *      use __vmalloc() instead.
 219  */
 220 void *vmalloc(unsigned long size)
 221 {
 222        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 223 }
 224 EXPORT_SYMBOL(vmalloc);
 225
 226 /*
 227  *      vzalloc - allocate virtually contiguous memory with zero fill
 228  *
 229  *      @size:          allocation size
 230  *
 231  *      Allocate enough pages to cover @size from the page level
 232  *      allocator and map them into contiguous kernel virtual space.
 233  *      The memory allocated is set to zero.
 234  *
 235  *      For tight control over page level allocator and protection flags
 236  *      use __vmalloc() instead.
 237  */
 238 void *vzalloc(unsigned long size)
 239 {
 240         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 241                         PAGE_KERNEL);
 242 }
 243 EXPORT_SYMBOL(vzalloc);
 244
 245 /**
 246  * vmalloc_node - allocate memory on a specific node
 247  * @size:       allocation size
 248  * @node:       numa node
 249  *
 250  * Allocate enough pages to cover @size from the page level
 251  * allocator and map them into contiguous kernel virtual space.
 252  *
 253  * For tight control over page level allocator and protection flags
 254  * use __vmalloc() instead.
 255  */
 256 void *vmalloc_node(unsigned long size, int node)
 257 {
 258         return vmalloc(size);
 259 }
 260 EXPORT_SYMBOL(vmalloc_node);
 261
 262 /**
 263  * vzalloc_node - allocate memory on a specific node with zero fill
 264  * @size:       allocation size
 265  * @node:       numa node
 266  *
 267  * Allocate enough pages to cover @size from the page level
 268  * allocator and map them into contiguous kernel virtual space.
 269  * The memory allocated is set to zero.
 270  *
 271  * For tight control over page level allocator and protection flags
 272  * use __vmalloc() instead.
 273  */
 274 void *vzalloc_node(unsigned long size, int node)
 275 {
 276         return vzalloc(size);
 277 }
 278 EXPORT_SYMBOL(vzalloc_node);
 279
 280 /**
 281  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 282  *      @size:          allocation size
 283  *
 284  *      Kernel-internal function to allocate enough pages to cover @size
 285  *      the page level allocator and map them into contiguous and
 286  *      executable kernel virtual space.
 287  *
 288  *      For tight control over page level allocator and protection flags
 289  *      use __vmalloc() instead.
 290  */
 291
 292 void *vmalloc_exec(unsigned long size)
 293 {
 294         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 295 }
 296
 297 /**
 298  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 299  *      @size:          allocation size
 300  *
 301  *      Allocate enough 32bit PA addressable pages to cover @size from the
 302  *      page level allocator and map them into contiguous kernel virtual space.
 303  */
 304 void *vmalloc_32(unsigned long size)
 305 {
 306         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 307 }
 308 EXPORT_SYMBOL(vmalloc_32);
 309
 310 /**
 311  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 312  *      @size:          allocation size
 313  *
 314  * The resulting memory area is 32bit addressable and zeroed so it can be
 315  * mapped to userspace without leaking data.
 316  *
 317  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 318  * remap_vmalloc_range() are permissible.
 319  */
 320 void *vmalloc_32_user(unsigned long size)
 321 {
 322         /*
 323          * We'll have to sort out the ZONE_DMA bits for 64-bit,
 324          * but for now this can simply use vmalloc_user() directly.
 325          */
 326         return vmalloc_user(size);
 327 }
 328 EXPORT_SYMBOL(vmalloc_32_user);
 329
 330 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 331 {
 332         BUG();
 333         return NULL;
 334 }
 335 EXPORT_SYMBOL(vmap);
 336
 337 void vunmap(const void *addr)
 338 {
 339         BUG();
 340 }
 341 EXPORT_SYMBOL(vunmap);
 342
 343 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
 344 {
 345         BUG();
 346         return NULL;
 347 }
 348 EXPORT_SYMBOL(vm_map_ram);
 349
 350 void vm_unmap_ram(const void *mem, unsigned int count)
 351 {
 352         BUG();
 353 }
 354 EXPORT_SYMBOL(vm_unmap_ram);
 355
 356 void vm_unmap_aliases(void)
 357 {
 358 }
 359 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 360
 361 /*
 362  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 363  * have one.
 364  */
 365 void __weak vmalloc_sync_all(void)
 366 {
 367 }
 368
 369 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
 370 {
 371         BUG();
 372         return NULL;
 373 }
 374 EXPORT_SYMBOL_GPL(alloc_vm_area);
 375
 376 void free_vm_area(struct vm_struct *area)
 377 {
 378         BUG();
 379 }
 380 EXPORT_SYMBOL_GPL(free_vm_area);
 381
 382 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 383                    struct page *page)
 384 {
 385         return -EINVAL;
 386 }
 387 EXPORT_SYMBOL(vm_insert_page);
 388
 389 int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
 390                         unsigned long num)
 391 {
 392         return -EINVAL;
 393 }
 394 EXPORT_SYMBOL(vm_map_pages);
 395
 396 int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
 397                                 unsigned long num)
 398 {
 399         return -EINVAL;
 400 }
 401 EXPORT_SYMBOL(vm_map_pages_zero);
 402
 403 /*
 404  *  sys_brk() for the most part doesn't need the global kernel
 405  *  lock, except when an application is doing something nasty
 406  *  like trying to un-brk an area that has already been mapped
 407  *  to a regular file.  in this case, the unmapping will need
 408  *  to invoke file system routines that need the global lock.
 409  */
 410 SYSCALL_DEFINE1(brk, unsigned long, brk)
 411 {
 412         struct mm_struct *mm = current->mm;
 413
 414         if (brk < mm->start_brk || brk > mm->context.end_brk)
 415                 return mm->brk;
 416
 417         if (mm->brk == brk)
 418                 return mm->brk;
 419
 420         /*
 421          * Always allow shrinking brk
 422          */
 423         if (brk <= mm->brk) {
 424                 mm->brk = brk;
 425                 return brk;
 426         }
 427
 428         /*
 429          * Ok, looks good - let it rip.
 430          */
 431         flush_icache_range(mm->brk, brk);
 432         return mm->brk = brk;
 433 }
 434
 435 /*
 436  * initialise the percpu counter for VM and region record slabs
 437  */
 438 void __init mmap_init(void)
 439 {
 440         int ret;
 441
 442         ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
 443         VM_BUG_ON(ret);
 444         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
 445 }
 446
 447 /*
 448  * validate the region tree
 449  * - the caller must hold the region lock
 450  */
 451 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
 452 static noinline void validate_nommu_regions(void)
 453 {
 454         struct vm_region *region, *last;
 455         struct rb_node *p, *lastp;
 456
 457         lastp = rb_first(&nommu_region_tree);
 458         if (!lastp)
 459                 return;
 460
 461         last = rb_entry(lastp, struct vm_region, vm_rb);
 462         BUG_ON(last->vm_end <= last->vm_start);
 463         BUG_ON(last->vm_top < last->vm_end);
 464
 465         while ((p = rb_next(lastp))) {
 466                 region = rb_entry(p, struct vm_region, vm_rb);
 467                 last = rb_entry(lastp, struct vm_region, vm_rb);
 468
 469                 BUG_ON(region->vm_end <= region->vm_start);
 470                 BUG_ON(region->vm_top < region->vm_end);
 471                 BUG_ON(region->vm_start < last->vm_top);
 472
 473                 lastp = p;
 474         }
 475 }
 476 #else
 477 static void validate_nommu_regions(void)
 478 {
 479 }
 480 #endif
 481
 482 /*
 483  * add a region into the global tree
 484  */
 485 static void add_nommu_region(struct vm_region *region)
 486 {
 487         struct vm_region *pregion;
 488         struct rb_node **p, *parent;
 489
 490         validate_nommu_regions();
 491
 492         parent = NULL;
 493         p = &nommu_region_tree.rb_node;
 494         while (*p) {
 495                 parent = *p;
 496                 pregion = rb_entry(parent, struct vm_region, vm_rb);
 497                 if (region->vm_start < pregion->vm_start)
 498                         p = &(*p)->rb_left;
 499                 else if (region->vm_start > pregion->vm_start)
 500                         p = &(*p)->rb_right;
 501                 else if (pregion == region)
 502                         return;
 503                 else
 504                         BUG();
 505         }
 506
 507         rb_link_node(&region->vm_rb, parent, p);
 508         rb_insert_color(&region->vm_rb, &nommu_region_tree);
 509
 510         validate_nommu_regions();
 511 }
 512
 513 /*
 514  * delete a region from the global tree
 515  */
 516 static void delete_nommu_region(struct vm_region *region)
 517 {
 518         BUG_ON(!nommu_region_tree.rb_node);
 519
 520         validate_nommu_regions();
 521         rb_erase(&region->vm_rb, &nommu_region_tree);
 522         validate_nommu_regions();
 523 }
 524
 525 /*
 526  * free a contiguous series of pages
 527  */
 528 static void free_page_series(unsigned long from, unsigned long to)
 529 {
 530         for (; from < to; from += PAGE_SIZE) {
 531                 struct page *page = virt_to_page(from);
 532
 533                 atomic_long_dec(&mmap_pages_allocated);
 534                 put_page(page);
 535         }
 536 }
 537
 538 /*
 539  * release a reference to a region
 540  * - the caller must hold the region semaphore for writing, which this releases
 541  * - the region may not have been added to the tree yet, in which case vm_top
 542  *   will equal vm_start
 543  */
 544 static void __put_nommu_region(struct vm_region *region)
 545         __releases(nommu_region_sem)
 546 {
 547         BUG_ON(!nommu_region_tree.rb_node);
 548
 549         if (--region->vm_usage == 0) {
 550                 if (region->vm_top > region->vm_start)
 551                         delete_nommu_region(region);
 552                 up_write(&nommu_region_sem);
 553
 554                 if (region->vm_file)
 555                         fput(region->vm_file);
 556
 557                 /* IO memory and memory shared directly out of the pagecache
 558                  * from ramfs/tmpfs mustn't be released here */
 559                 if (region->vm_flags & VM_MAPPED_COPY)
 560                         free_page_series(region->vm_start, region->vm_top);
 561                 kmem_cache_free(vm_region_jar, region);
 562         } else {
 563                 up_write(&nommu_region_sem);
 564         }
 565 }
 566
 567 /*
 568  * release a reference to a region
 569  */
 570 static void put_nommu_region(struct vm_region *region)
 571 {
 572         down_write(&nommu_region_sem);
 573         __put_nommu_region(region);
 574 }
 575
 576 /*
 577  * add a VMA into a process's mm_struct in the appropriate place in the list
 578  * and tree and add to the address space's page tree also if not an anonymous
 579  * page
 580  * - should be called with mm->mmap_sem held writelocked
 581  */
 582 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 583 {
 584         struct vm_area_struct *pvma, *prev;
 585         struct address_space *mapping;
 586         struct rb_node **p, *parent, *rb_prev;
 587
 588         BUG_ON(!vma->vm_region);
 589
 590         mm->map_count++;
 591         vma->vm_mm = mm;
 592
 593         /* add the VMA to the mapping */
 594         if (vma->vm_file) {
 595                 mapping = vma->vm_file->f_mapping;
 596
 597                 i_mmap_lock_write(mapping);
 598                 flush_dcache_mmap_lock(mapping);
 599                 vma_interval_tree_insert(vma, &mapping->i_mmap);
 600                 flush_dcache_mmap_unlock(mapping);
 601                 i_mmap_unlock_write(mapping);
 602         }
 603
 604         /* add the VMA to the tree */
 605         parent = rb_prev = NULL;
 606         p = &mm->mm_rb.rb_node;
 607         while (*p) {
 608                 parent = *p;
 609                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 610
 611                 /* sort by: start addr, end addr, VMA struct addr in that order
 612                  * (the latter is necessary as we may get identical VMAs) */
 613                 if (vma->vm_start < pvma->vm_start)
 614                         p = &(*p)->rb_left;
 615                 else if (vma->vm_start > pvma->vm_start) {
 616                         rb_prev = parent;
 617                         p = &(*p)->rb_right;
 618                 } else if (vma->vm_end < pvma->vm_end)
 619                         p = &(*p)->rb_left;
 620                 else if (vma->vm_end > pvma->vm_end) {
 621                         rb_prev = parent;
 622                         p = &(*p)->rb_right;
 623                 } else if (vma < pvma)
 624                         p = &(*p)->rb_left;
 625                 else if (vma > pvma) {
 626                         rb_prev = parent;
 627                         p = &(*p)->rb_right;
 628                 } else
 629                         BUG();
 630         }
 631
 632         rb_link_node(&vma->vm_rb, parent, p);
 633         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 634
 635         /* add VMA to the VMA list also */
 636         prev = NULL;
 637         if (rb_prev)
 638                 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 639
 640         __vma_link_list(mm, vma, prev, parent);
 641 }
 642
 643 /*
 644  * delete a VMA from its owning mm_struct and address space
 645  */
 646 static void delete_vma_from_mm(struct vm_area_struct *vma)
 647 {
 648         int i;
 649         struct address_space *mapping;
 650         struct mm_struct *mm = vma->vm_mm;
 651         struct task_struct *curr = current;
 652
 653         mm->map_count--;
 654         for (i = 0; i < VMACACHE_SIZE; i++) {
 655                 /* if the vma is cached, invalidate the entire cache */
 656                 if (curr->vmacache.vmas[i] == vma) {
 657                         vmacache_invalidate(mm);
 658                         break;
 659                 }
 660         }
 661
 662         /* remove the VMA from the mapping */
 663         if (vma->vm_file) {
 664                 mapping = vma->vm_file->f_mapping;
 665
 666                 i_mmap_lock_write(mapping);
 667                 flush_dcache_mmap_lock(mapping);
 668                 vma_interval_tree_remove(vma, &mapping->i_mmap);
 669                 flush_dcache_mmap_unlock(mapping);
 670                 i_mmap_unlock_write(mapping);
 671         }
 672
 673         /* remove from the MM's tree and list */
 674         rb_erase(&vma->vm_rb, &mm->mm_rb);
 675
 676         if (vma->vm_prev)
 677                 vma->vm_prev->vm_next = vma->vm_next;
 678         else
 679                 mm->mmap = vma->vm_next;
 680
 681         if (vma->vm_next)
 682                 vma->vm_next->vm_prev = vma->vm_prev;
 683 }
 684
 685 /*
 686  * destroy a VMA record
 687  */
 688 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 689 {
 690         if (vma->vm_ops && vma->vm_ops->close)
 691                 vma->vm_ops->close(vma);
 692         if (vma->vm_file)
 693                 fput(vma->vm_file);
 694         put_nommu_region(vma->vm_region);
 695         vm_area_free(vma);
 696 }
 697
 698 /*
 699  * look up the first VMA in which addr resides, NULL if none
 700  * - should be called with mm->mmap_sem at least held readlocked
 701  */
 702 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 703 {
 704         struct vm_area_struct *vma;
 705
 706         /* check the cache first */
 707         vma = vmacache_find(mm, addr);
 708         if (likely(vma))
 709                 return vma;
 710
 711         /* trawl the list (there may be multiple mappings in which addr
 712          * resides) */
 713         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 714                 if (vma->vm_start > addr)
 715                         return NULL;
 716                 if (vma->vm_end > addr) {
 717                         vmacache_update(addr, vma);
 718                         return vma;
 719                 }
 720         }
 721
 722         return NULL;
 723 }
 724 EXPORT_SYMBOL(find_vma);
 725
 726 /*
 727  * find a VMA
 728  * - we don't extend stack VMAs under NOMMU conditions
 729  */
 730 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 731 {
 732         return find_vma(mm, addr);
 733 }
 734
 735 /*
 736  * expand a stack to a given address
 737  * - not supported under NOMMU conditions
 738  */
 739 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 740 {
 741         return -ENOMEM;
 742 }
 743
 744 /*
 745  * look up the first VMA exactly that exactly matches addr
 746  * - should be called with mm->mmap_sem at least held readlocked
 747  */
 748 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 749                                              unsigned long addr,
 750                                              unsigned long len)
 751 {
 752         struct vm_area_struct *vma;
 753         unsigned long end = addr + len;
 754
 755         /* check the cache first */
 756         vma = vmacache_find_exact(mm, addr, end);
 757         if (vma)
 758                 return vma;
 759
 760         /* trawl the list (there may be multiple mappings in which addr
 761          * resides) */
 762         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 763                 if (vma->vm_start < addr)
 764                         continue;
 765                 if (vma->vm_start > addr)
 766                         return NULL;
 767                 if (vma->vm_end == end) {
 768                         vmacache_update(addr, vma);
 769                         return vma;
 770                 }
 771         }
 772
 773         return NULL;
 774 }
 775
 776 /*
 777  * determine whether a mapping should be permitted and, if so, what sort of
 778  * mapping we're capable of supporting
 779  */
 780 static int validate_mmap_request(struct file *file,
 781                                  unsigned long addr,
 782                                  unsigned long len,
 783                                  unsigned long prot,
 784                                  unsigned long flags,
 785                                  unsigned long pgoff,
 786                                  unsigned long *_capabilities)
 787 {
 788         unsigned long capabilities, rlen;
 789         int ret;
 790
 791         /* do the simple checks first */
 792         if (flags & MAP_FIXED)
 793                 return -EINVAL;
 794
 795         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 796             (flags & MAP_TYPE) != MAP_SHARED)
 797                 return -EINVAL;
 798
 799         if (!len)
 800                 return -EINVAL;
 801
 802         /* Careful about overflows.. */
 803         rlen = PAGE_ALIGN(len);
 804         if (!rlen || rlen > TASK_SIZE)
 805                 return -ENOMEM;
 806
 807         /* offset overflow? */
 808         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
 809                 return -EOVERFLOW;
 810
 811         if (file) {
 812                 /* files must support mmap */
 813                 if (!file->f_op->mmap)
 814                         return -ENODEV;
 815
 816                 /* work out if what we've got could possibly be shared
 817                  * - we support chardevs that provide their own "memory"
 818                  * - we support files/blockdevs that are memory backed
 819                  */
 820                 if (file->f_op->mmap_capabilities) {
 821                         capabilities = file->f_op->mmap_capabilities(file);
 822                 } else {
 823                         /* no explicit capabilities set, so assume some
 824                          * defaults */
 825                         switch (file_inode(file)->i_mode & S_IFMT) {
 826                         case S_IFREG:
 827                         case S_IFBLK:
 828                                 capabilities = NOMMU_MAP_COPY;
 829                                 break;
 830
 831                         case S_IFCHR:
 832                                 capabilities =
 833                                         NOMMU_MAP_DIRECT |
 834                                         NOMMU_MAP_READ |
 835                                         NOMMU_MAP_WRITE;
 836                                 break;
 837
 838                         default:
 839                                 return -EINVAL;
 840                         }
 841                 }
 842
 843                 /* eliminate any capabilities that we can't support on this
 844                  * device */
 845                 if (!file->f_op->get_unmapped_area)
 846                         capabilities &= ~NOMMU_MAP_DIRECT;
 847                 if (!(file->f_mode & FMODE_CAN_READ))
 848                         capabilities &= ~NOMMU_MAP_COPY;
 849
 850                 /* The file shall have been opened with read permission. */
 851                 if (!(file->f_mode & FMODE_READ))
 852                         return -EACCES;
 853
 854                 if (flags & MAP_SHARED) {
 855                         /* do checks for writing, appending and locking */
 856                         if ((prot & PROT_WRITE) &&
 857                             !(file->f_mode & FMODE_WRITE))
 858                                 return -EACCES;
 859
 860                         if (IS_APPEND(file_inode(file)) &&
 861                             (file->f_mode & FMODE_WRITE))
 862                                 return -EACCES;
 863
 864                         if (locks_verify_locked(file))
 865                                 return -EAGAIN;
 866
 867                         if (!(capabilities & NOMMU_MAP_DIRECT))
 868                                 return -ENODEV;
 869
 870                         /* we mustn't privatise shared mappings */
 871                         capabilities &= ~NOMMU_MAP_COPY;
 872                 } else {
 873                         /* we're going to read the file into private memory we
 874                          * allocate */
 875                         if (!(capabilities & NOMMU_MAP_COPY))
 876                                 return -ENODEV;
 877
 878                         /* we don't permit a private writable mapping to be
 879                          * shared with the backing device */
 880                         if (prot & PROT_WRITE)
 881                                 capabilities &= ~NOMMU_MAP_DIRECT;
 882                 }
 883
 884                 if (capabilities & NOMMU_MAP_DIRECT) {
 885                         if (((prot & PROT_READ)  && !(capabilities & NOMMU_MAP_READ))  ||
 886                             ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) ||
 887                             ((prot & PROT_EXEC)  && !(capabilities & NOMMU_MAP_EXEC))
 888                             ) {
 889                                 capabilities &= ~NOMMU_MAP_DIRECT;
 890                                 if (flags & MAP_SHARED) {
 891                                         pr_warn("MAP_SHARED not completely supported on !MMU\n");
 892                                         return -EINVAL;
 893                                 }
 894                         }
 895                 }
 896
 897                 /* handle executable mappings and implied executable
 898                  * mappings */
 899                 if (path_noexec(&file->f_path)) {
 900                         if (prot & PROT_EXEC)
 901                                 return -EPERM;
 902                 } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 903                         /* handle implication of PROT_EXEC by PROT_READ */
 904                         if (current->personality & READ_IMPLIES_EXEC) {
 905                                 if (capabilities & NOMMU_MAP_EXEC)
 906                                         prot |= PROT_EXEC;
 907                         }
 908                 } else if ((prot & PROT_READ) &&
 909                          (prot & PROT_EXEC) &&
 910                          !(capabilities & NOMMU_MAP_EXEC)
 911                          ) {
 912                         /* backing file is not executable, try to copy */
 913                         capabilities &= ~NOMMU_MAP_DIRECT;
 914                 }
 915         } else {
 916                 /* anonymous mappings are always memory backed and can be
 917                  * privately mapped
 918                  */
 919                 capabilities = NOMMU_MAP_COPY;
 920
 921                 /* handle PROT_EXEC implication by PROT_READ */
 922                 if ((prot & PROT_READ) &&
 923                     (current->personality & READ_IMPLIES_EXEC))
 924                         prot |= PROT_EXEC;
 925         }
 926
 927         /* allow the security API to have its say */
 928         ret = security_mmap_addr(addr);
 929         if (ret < 0)
 930                 return ret;
 931
 932         /* looks okay */
 933         *_capabilities = capabilities;
 934         return 0;
 935 }
 936
 937 /*
 938  * we've determined that we can make the mapping, now translate what we
 939  * now know into VMA flags
 940  */
 941 static unsigned long determine_vm_flags(struct file *file,
 942                                         unsigned long prot,
 943                                         unsigned long flags,
 944                                         unsigned long capabilities)
 945 {
 946         unsigned long vm_flags;
 947
 948         vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
 949         /* vm_flags |= mm->def_flags; */
 950
 951         if (!(capabilities & NOMMU_MAP_DIRECT)) {
 952                 /* attempt to share read-only copies of mapped file chunks */
 953                 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 954                 if (file && !(prot & PROT_WRITE))
 955                         vm_flags |= VM_MAYSHARE;
 956         } else {
 957                 /* overlay a shareable mapping on the backing device or inode
 958                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 959                  * romfs/cramfs */
 960                 vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS);
 961                 if (flags & MAP_SHARED)
 962                         vm_flags |= VM_SHARED;
 963         }
 964
 965         /* refuse to let anyone share private mappings with this process if
 966          * it's being traced - otherwise breakpoints set in it may interfere
 967          * with another untraced process
 968          */
 969         if ((flags & MAP_PRIVATE) && current->ptrace)
 970                 vm_flags &= ~VM_MAYSHARE;
 971
 972         return vm_flags;
 973 }
 974
 975 /*
 976  * set up a shared mapping on a file (the driver or filesystem provides and
 977  * pins the storage)
 978  */
 979 static int do_mmap_shared_file(struct vm_area_struct *vma)
 980 {
 981         int ret;
 982
 983         ret = call_mmap(vma->vm_file, vma);
 984         if (ret == 0) {
 985                 vma->vm_region->vm_top = vma->vm_region->vm_end;
 986                 return 0;
 987         }
 988         if (ret != -ENOSYS)
 989                 return ret;
 990
 991         /* getting -ENOSYS indicates that direct mmap isn't possible (as
 992          * opposed to tried but failed) so we can only give a suitable error as
 993          * it's not possible to make a private copy if MAP_SHARED was given */
 994         return -ENODEV;
 995 }
 996
 997 /*
 998  * set up a private mapping or an anonymous shared mapping
 999  */
1000 static int do_mmap_private(struct vm_area_struct *vma,
1001                            struct vm_region *region,
1002                            unsigned long len,
1003                            unsigned long capabilities)
1004 {
1005         unsigned long total, point;
1006         void *base;
1007         int ret, order;
1008
1009         /* invoke the file's mapping function so that it can keep track of
1010          * shared mappings on devices or memory
1011          * - VM_MAYSHARE will be set if it may attempt to share
1012          */
1013         if (capabilities & NOMMU_MAP_DIRECT) {
1014                 ret = call_mmap(vma->vm_file, vma);
1015                 if (ret == 0) {
1016                         /* shouldn't return success if we're not sharing */
1017                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1018                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1019                         return 0;
1020                 }
1021                 if (ret != -ENOSYS)
1022                         return ret;
1023
1024                 /* getting an ENOSYS error indicates that direct mmap isn't
1025                  * possible (as opposed to tried but failed) so we'll try to
1026                  * make a private copy of the data and map that instead */
1027         }
1028
1029
1030         /* allocate some memory to hold the mapping
1031          * - note that this may not return a page-aligned address if the object
1032          *   we're allocating is smaller than a page
1033          */
1034         order = get_order(len);
1035         total = 1 << order;
1036         point = len >> PAGE_SHIFT;
1037
1038         /* we don't want to allocate a power-of-2 sized page set */
1039         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages)
1040                 total = point;
1041
1042         base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
1043         if (!base)
1044                 goto enomem;
1045
1046         atomic_long_add(total, &mmap_pages_allocated);
1047
1048         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1049         region->vm_start = (unsigned long) base;
1050         region->vm_end   = region->vm_start + len;
1051         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1052
1053         vma->vm_start = region->vm_start;
1054         vma->vm_end   = region->vm_start + len;
1055
1056         if (vma->vm_file) {
1057                 /* read the contents of a file into the copy */
1058                 loff_t fpos;
1059
1060                 fpos = vma->vm_pgoff;
1061                 fpos <<= PAGE_SHIFT;
1062
1063                 ret = kernel_read(vma->vm_file, base, len, &fpos);
1064                 if (ret < 0)
1065                         goto error_free;
1066
1067                 /* clear the last little bit */
1068                 if (ret < len)
1069                         memset(base + ret, 0, len - ret);
1070
1071         } else {
1072                 vma_set_anonymous(vma);
1073         }
1074
1075         return 0;
1076
1077 error_free:
1078         free_page_series(region->vm_start, region->vm_top);
1079         region->vm_start = vma->vm_start = 0;
1080         region->vm_end   = vma->vm_end = 0;
1081         region->vm_top   = 0;
1082         return ret;
1083
1084 enomem:
1085         pr_err("Allocation of length %lu from process %d (%s) failed\n",
1086                len, current->pid, current->comm);
1087         show_free_areas(0, NULL);
1088         return -ENOMEM;
1089 }
1090
1091 /*
1092  * handle mapping creation for uClinux
1093  */
1094 unsigned long do_mmap(struct file *file,
1095                         unsigned long addr,
1096                         unsigned long len,
1097                         unsigned long prot,
1098                         unsigned long flags,
1099                         vm_flags_t vm_flags,
1100                         unsigned long pgoff,
1101                         unsigned long *populate,
1102                         struct list_head *uf)
1103 {
1104         struct vm_area_struct *vma;
1105         struct vm_region *region;
1106         struct rb_node *rb;
1107         unsigned long capabilities, result;
1108         int ret;
1109
1110         *populate = 0;
1111
1112         /* decide whether we should attempt the mapping, and if so what sort of
1113          * mapping */
1114         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1115                                     &capabilities);
1116         if (ret < 0)
1117                 return ret;
1118
1119         /* we ignore the address hint */
1120         addr = 0;
1121         len = PAGE_ALIGN(len);
1122
1123         /* we've determined that we can make the mapping, now translate what we
1124          * now know into VMA flags */
1125         vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
1126
1127         /* we're going to need to record the mapping */
1128         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1129         if (!region)
1130                 goto error_getting_region;
1131
1132         vma = vm_area_alloc(current->mm);
1133         if (!vma)
1134                 goto error_getting_vma;
1135
1136         region->vm_usage = 1;
1137         region->vm_flags = vm_flags;
1138         region->vm_pgoff = pgoff;
1139
1140         vma->vm_flags = vm_flags;
1141         vma->vm_pgoff = pgoff;
1142
1143         if (file) {
1144                 region->vm_file = get_file(file);
1145                 vma->vm_file = get_file(file);
1146         }
1147
1148         down_write(&nommu_region_sem);
1149
1150         /* if we want to share, we need to check for regions created by other
1151          * mmap() calls that overlap with our proposed mapping
1152          * - we can only share with a superset match on most regular files
1153          * - shared mappings on character devices and memory backed files are
1154          *   permitted to overlap inexactly as far as we are concerned for in
1155          *   these cases, sharing is handled in the driver or filesystem rather
1156          *   than here
1157          */
1158         if (vm_flags & VM_MAYSHARE) {
1159                 struct vm_region *pregion;
1160                 unsigned long pglen, rpglen, pgend, rpgend, start;
1161
1162                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1163                 pgend = pgoff + pglen;
1164
1165                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1166                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1167
1168                         if (!(pregion->vm_flags & VM_MAYSHARE))
1169                                 continue;
1170
1171                         /* search for overlapping mappings on the same file */
1172                         if (file_inode(pregion->vm_file) !=
1173                             file_inode(file))
1174                                 continue;
1175
1176                         if (pregion->vm_pgoff >= pgend)
1177                                 continue;
1178
1179                         rpglen = pregion->vm_end - pregion->vm_start;
1180                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1181                         rpgend = pregion->vm_pgoff + rpglen;
1182                         if (pgoff >= rpgend)
1183                                 continue;
1184
1185                         /* handle inexactly overlapping matches between
1186                          * mappings */
1187                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1188                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1189                                 /* new mapping is not a subset of the region */
1190                                 if (!(capabilities & NOMMU_MAP_DIRECT))
1191                                         goto sharing_violation;
1192                                 continue;
1193                         }
1194
1195                         /* we've found a region we can share */
1196                         pregion->vm_usage++;
1197                         vma->vm_region = pregion;
1198                         start = pregion->vm_start;
1199                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1200                         vma->vm_start = start;
1201                         vma->vm_end = start + len;
1202
1203                         if (pregion->vm_flags & VM_MAPPED_COPY)
1204                                 vma->vm_flags |= VM_MAPPED_COPY;
1205                         else {
1206                                 ret = do_mmap_shared_file(vma);
1207                                 if (ret < 0) {
1208                                         vma->vm_region = NULL;
1209                                         vma->vm_start = 0;
1210                                         vma->vm_end = 0;
1211                                         pregion->vm_usage--;
1212                                         pregion = NULL;
1213                                         goto error_just_free;
1214                                 }
1215                         }
1216                         fput(region->vm_file);
1217                         kmem_cache_free(vm_region_jar, region);
1218                         region = pregion;
1219                         result = start;
1220                         goto share;
1221                 }
1222
1223                 /* obtain the address at which to make a shared mapping
1224                  * - this is the hook for quasi-memory character devices to
1225                  *   tell us the location of a shared mapping
1226                  */
1227                 if (capabilities & NOMMU_MAP_DIRECT) {
1228                         addr = file->f_op->get_unmapped_area(file, addr, len,
1229                                                              pgoff, flags);
1230                         if (IS_ERR_VALUE(addr)) {
1231                                 ret = addr;
1232                                 if (ret != -ENOSYS)
1233                                         goto error_just_free;
1234
1235                                 /* the driver refused to tell us where to site
1236                                  * the mapping so we'll have to attempt to copy
1237                                  * it */
1238                                 ret = -ENODEV;
1239                                 if (!(capabilities & NOMMU_MAP_COPY))
1240                                         goto error_just_free;
1241
1242                                 capabilities &= ~NOMMU_MAP_DIRECT;
1243                         } else {
1244                                 vma->vm_start = region->vm_start = addr;
1245                                 vma->vm_end = region->vm_end = addr + len;
1246                         }
1247                 }
1248         }
1249
1250         vma->vm_region = region;
1251
1252         /* set up the mapping
1253          * - the region is filled in if NOMMU_MAP_DIRECT is still set
1254          */
1255         if (file && vma->vm_flags & VM_SHARED)
1256                 ret = do_mmap_shared_file(vma);
1257         else
1258                 ret = do_mmap_private(vma, region, len, capabilities);
1259         if (ret < 0)
1260                 goto error_just_free;
1261         add_nommu_region(region);
1262
1263         /* clear anonymous mappings that don't ask for uninitialized data */
1264         if (!vma->vm_file &&
1265             (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) ||
1266              !(flags & MAP_UNINITIALIZED)))
1267                 memset((void *)region->vm_start, 0,
1268                        region->vm_end - region->vm_start);
1269
1270         /* okay... we have a mapping; now we have to register it */
1271         result = vma->vm_start;
1272
1273         current->mm->total_vm += len >> PAGE_SHIFT;
1274
1275 share:
1276         add_vma_to_mm(current->mm, vma);
1277
1278         /* we flush the region from the icache only when the first executable
1279          * mapping of it is made  */
1280         if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1281                 flush_icache_range(region->vm_start, region->vm_end);
1282                 region->vm_icache_flushed = true;
1283         }
1284
1285         up_write(&nommu_region_sem);
1286
1287         return result;
1288
1289 error_just_free:
1290         up_write(&nommu_region_sem);
1291 error:
1292         if (region->vm_file)
1293                 fput(region->vm_file);
1294         kmem_cache_free(vm_region_jar, region);
1295         if (vma->vm_file)
1296                 fput(vma->vm_file);
1297         vm_area_free(vma);
1298         return ret;
1299
1300 sharing_violation:
1301         up_write(&nommu_region_sem);
1302         pr_warn("Attempt to share mismatched mappings\n");
1303         ret = -EINVAL;
1304         goto error;
1305
1306 error_getting_vma:
1307         kmem_cache_free(vm_region_jar, region);
1308         pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1309                         len, current->pid);
1310         show_free_areas(0, NULL);
1311         return -ENOMEM;
1312
1313 error_getting_region:
1314         pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1315                         len, current->pid);
1316         show_free_areas(0, NULL);
1317         return -ENOMEM;
1318 }
1319
1320 unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1321                               unsigned long prot, unsigned long flags,
1322                               unsigned long fd, unsigned long pgoff)
1323 {
1324         struct file *file = NULL;
1325         unsigned long retval = -EBADF;
1326
1327         audit_mmap_fd(fd, flags);
1328         if (!(flags & MAP_ANONYMOUS)) {
1329                 file = fget(fd);
1330                 if (!file)
1331                         goto out;
1332         }
1333
1334         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1335
1336         retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1337
1338         if (file)
1339                 fput(file);
1340 out:
1341         return retval;
1342 }
1343
1344 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1345                 unsigned long, prot, unsigned long, flags,
1346                 unsigned long, fd, unsigned long, pgoff)
1347 {
1348         return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1349 }
1350
1351 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1352 struct mmap_arg_struct {
1353         unsigned long addr;
1354         unsigned long len;
1355         unsigned long prot;
1356         unsigned long flags;
1357         unsigned long fd;
1358         unsigned long offset;
1359 };
1360
1361 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1362 {
1363         struct mmap_arg_struct a;
1364
1365         if (copy_from_user(&a, arg, sizeof(a)))
1366                 return -EFAULT;
1367         if (offset_in_page(a.offset))
1368                 return -EINVAL;
1369
1370         return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1371                                a.offset >> PAGE_SHIFT);
1372 }
1373 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1374
1375 /*
1376  * split a vma into two pieces at address 'addr', a new vma is allocated either
1377  * for the first part or the tail.
1378  */
1379 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1380               unsigned long addr, int new_below)
1381 {
1382         struct vm_area_struct *new;
1383         struct vm_region *region;
1384         unsigned long npages;
1385
1386         /* we're only permitted to split anonymous regions (these should have
1387          * only a single usage on the region) */
1388         if (vma->vm_file)
1389                 return -ENOMEM;
1390
1391         if (mm->map_count >= sysctl_max_map_count)
1392                 return -ENOMEM;
1393
1394         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1395         if (!region)
1396                 return -ENOMEM;
1397
1398         new = vm_area_dup(vma);
1399         if (!new) {
1400                 kmem_cache_free(vm_region_jar, region);
1401                 return -ENOMEM;
1402         }
1403
1404         /* most fields are the same, copy all, and then fixup */
1405         *region = *vma->vm_region;
1406         new->vm_region = region;
1407
1408         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1409
1410         if (new_below) {
1411                 region->vm_top = region->vm_end = new->vm_end = addr;
1412         } else {
1413                 region->vm_start = new->vm_start = addr;
1414                 region->vm_pgoff = new->vm_pgoff += npages;
1415         }
1416
1417         if (new->vm_ops && new->vm_ops->open)
1418                 new->vm_ops->open(new);
1419
1420         delete_vma_from_mm(vma);
1421         down_write(&nommu_region_sem);
1422         delete_nommu_region(vma->vm_region);
1423         if (new_below) {
1424                 vma->vm_region->vm_start = vma->vm_start = addr;
1425                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1426         } else {
1427                 vma->vm_region->vm_end = vma->vm_end = addr;
1428                 vma->vm_region->vm_top = addr;
1429         }
1430         add_nommu_region(vma->vm_region);
1431         add_nommu_region(new->vm_region);
1432         up_write(&nommu_region_sem);
1433         add_vma_to_mm(mm, vma);
1434         add_vma_to_mm(mm, new);
1435         return 0;
1436 }
1437
1438 /*
1439  * shrink a VMA by removing the specified chunk from either the beginning or
1440  * the end
1441  */
1442 static int shrink_vma(struct mm_struct *mm,
1443                       struct vm_area_struct *vma,
1444                       unsigned long from, unsigned long to)
1445 {
1446         struct vm_region *region;
1447
1448         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1449          * and list */
1450         delete_vma_from_mm(vma);
1451         if (from > vma->vm_start)
1452                 vma->vm_end = from;
1453         else
1454                 vma->vm_start = to;
1455         add_vma_to_mm(mm, vma);
1456
1457         /* cut the backing region down to size */
1458         region = vma->vm_region;
1459         BUG_ON(region->vm_usage != 1);
1460
1461         down_write(&nommu_region_sem);
1462         delete_nommu_region(region);
1463         if (from > region->vm_start) {
1464                 to = region->vm_top;
1465                 region->vm_top = region->vm_end = from;
1466         } else {
1467                 region->vm_start = to;
1468         }
1469         add_nommu_region(region);
1470         up_write(&nommu_region_sem);
1471
1472         free_page_series(from, to);
1473         return 0;
1474 }
1475
1476 /*
1477  * release a mapping
1478  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1479  *   VMA, though it need not cover the whole VMA
1480  */
1481 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
1482 {
1483         struct vm_area_struct *vma;
1484         unsigned long end;
1485         int ret;
1486
1487         len = PAGE_ALIGN(len);
1488         if (len == 0)
1489                 return -EINVAL;
1490
1491         end = start + len;
1492
1493         /* find the first potentially overlapping VMA */
1494         vma = find_vma(mm, start);
1495         if (!vma) {
1496                 static int limit;
1497                 if (limit < 5) {
1498                         pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1499                                         current->pid, current->comm,
1500                                         start, start + len - 1);
1501                         limit++;
1502                 }
1503                 return -EINVAL;
1504         }
1505
1506         /* we're allowed to split an anonymous VMA but not a file-backed one */
1507         if (vma->vm_file) {
1508                 do {
1509                         if (start > vma->vm_start)
1510                                 return -EINVAL;
1511                         if (end == vma->vm_end)
1512                                 goto erase_whole_vma;
1513                         vma = vma->vm_next;
1514                 } while (vma);
1515                 return -EINVAL;
1516         } else {
1517                 /* the chunk must be a subset of the VMA found */
1518                 if (start == vma->vm_start && end == vma->vm_end)
1519                         goto erase_whole_vma;
1520                 if (start < vma->vm_start || end > vma->vm_end)
1521                         return -EINVAL;
1522                 if (offset_in_page(start))
1523                         return -EINVAL;
1524                 if (end != vma->vm_end && offset_in_page(end))
1525                         return -EINVAL;
1526                 if (start != vma->vm_start && end != vma->vm_end) {
1527                         ret = split_vma(mm, vma, start, 1);
1528                         if (ret < 0)
1529                                 return ret;
1530                 }
1531                 return shrink_vma(mm, vma, start, end);
1532         }
1533
1534 erase_whole_vma:
1535         delete_vma_from_mm(vma);
1536         delete_vma(mm, vma);
1537         return 0;
1538 }
1539 EXPORT_SYMBOL(do_munmap);
1540
1541 int vm_munmap(unsigned long addr, size_t len)
1542 {
1543         struct mm_struct *mm = current->mm;
1544         int ret;
1545
1546         down_write(&mm->mmap_sem);
1547         ret = do_munmap(mm, addr, len, NULL);
1548         up_write(&mm->mmap_sem);
1549         return ret;
1550 }
1551 EXPORT_SYMBOL(vm_munmap);
1552
1553 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1554 {
1555         return vm_munmap(addr, len);
1556 }
1557
1558 /*
1559  * release all the mappings made in a process's VM space
1560  */
1561 void exit_mmap(struct mm_struct *mm)
1562 {
1563         struct vm_area_struct *vma;
1564
1565         if (!mm)
1566                 return;
1567
1568         mm->total_vm = 0;
1569
1570         while ((vma = mm->mmap)) {
1571                 mm->mmap = vma->vm_next;
1572                 delete_vma_from_mm(vma);
1573                 delete_vma(mm, vma);
1574                 cond_resched();
1575         }
1576 }
1577
1578 int vm_brk(unsigned long addr, unsigned long len)
1579 {
1580         return -ENOMEM;
1581 }
1582
1583 /*
1584  * expand (or shrink) an existing mapping, potentially moving it at the same
1585  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1586  *
1587  * under NOMMU conditions, we only permit changing a mapping's size, and only
1588  * as long as it stays within the region allocated by do_mmap_private() and the
1589  * block is not shareable
1590  *
1591  * MREMAP_FIXED is not supported under NOMMU conditions
1592  */
1593 static unsigned long do_mremap(unsigned long addr,
1594                         unsigned long old_len, unsigned long new_len,
1595                         unsigned long flags, unsigned long new_addr)
1596 {
1597         struct vm_area_struct *vma;
1598
1599         /* insanity checks first */
1600         old_len = PAGE_ALIGN(old_len);
1601         new_len = PAGE_ALIGN(new_len);
1602         if (old_len == 0 || new_len == 0)
1603                 return (unsigned long) -EINVAL;
1604
1605         if (offset_in_page(addr))
1606                 return -EINVAL;
1607
1608         if (flags & MREMAP_FIXED && new_addr != addr)
1609                 return (unsigned long) -EINVAL;
1610
1611         vma = find_vma_exact(current->mm, addr, old_len);
1612         if (!vma)
1613                 return (unsigned long) -EINVAL;
1614
1615         if (vma->vm_end != vma->vm_start + old_len)
1616                 return (unsigned long) -EFAULT;
1617
1618         if (vma->vm_flags & VM_MAYSHARE)
1619                 return (unsigned long) -EPERM;
1620
1621         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1622                 return (unsigned long) -ENOMEM;
1623
1624         /* all checks complete - do it */
1625         vma->vm_end = vma->vm_start + new_len;
1626         return vma->vm_start;
1627 }
1628
1629 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1630                 unsigned long, new_len, unsigned long, flags,
1631                 unsigned long, new_addr)
1632 {
1633         unsigned long ret;
1634
1635         down_write(&current->mm->mmap_sem);
1636         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1637         up_write(&current->mm->mmap_sem);
1638         return ret;
1639 }
1640
1641 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1642                          unsigned int foll_flags)
1643 {
1644         return NULL;
1645 }
1646
1647 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1648                 unsigned long pfn, unsigned long size, pgprot_t prot)
1649 {
1650         if (addr != (pfn << PAGE_SHIFT))
1651                 return -EINVAL;
1652
1653         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1654         return 0;
1655 }
1656 EXPORT_SYMBOL(remap_pfn_range);
1657
1658 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1659 {
1660         unsigned long pfn = start >> PAGE_SHIFT;
1661         unsigned long vm_len = vma->vm_end - vma->vm_start;
1662
1663         pfn += vma->vm_pgoff;
1664         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1665 }
1666 EXPORT_SYMBOL(vm_iomap_memory);
1667
1668 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1669                         unsigned long pgoff)
1670 {
1671         unsigned int size = vma->vm_end - vma->vm_start;
1672
1673         if (!(vma->vm_flags & VM_USERMAP))
1674                 return -EINVAL;
1675
1676         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1677         vma->vm_end = vma->vm_start + size;
1678
1679         return 0;
1680 }
1681 EXPORT_SYMBOL(remap_vmalloc_range);
1682
1683 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1684         unsigned long len, unsigned long pgoff, unsigned long flags)
1685 {
1686         return -ENOMEM;
1687 }
1688
1689 vm_fault_t filemap_fault(struct vm_fault *vmf)
1690 {
1691         BUG();
1692         return 0;
1693 }
1694 EXPORT_SYMBOL(filemap_fault);
1695
1696 void filemap_map_pages(struct vm_fault *vmf,
1697                 pgoff_t start_pgoff, pgoff_t end_pgoff)
1698 {
1699         BUG();
1700 }
1701 EXPORT_SYMBOL(filemap_map_pages);
1702
1703 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1704                 unsigned long addr, void *buf, int len, unsigned int gup_flags)
1705 {
1706         struct vm_area_struct *vma;
1707         int write = gup_flags & FOLL_WRITE;
1708
1709         if (down_read_killable(&mm->mmap_sem))
1710                 return 0;
1711
1712         /* the access must start within one of the target process's mappings */
1713         vma = find_vma(mm, addr);
1714         if (vma) {
1715                 /* don't overrun this mapping */
1716                 if (addr + len >= vma->vm_end)
1717                         len = vma->vm_end - addr;
1718
1719                 /* only read or write mappings where it is permitted */
1720                 if (write && vma->vm_flags & VM_MAYWRITE)
1721                         copy_to_user_page(vma, NULL, addr,
1722                                          (void *) addr, buf, len);
1723                 else if (!write && vma->vm_flags & VM_MAYREAD)
1724                         copy_from_user_page(vma, NULL, addr,
1725                                             buf, (void *) addr, len);
1726                 else
1727                         len = 0;
1728         } else {
1729                 len = 0;
1730         }
1731
1732         up_read(&mm->mmap_sem);
1733
1734         return len;
1735 }
1736
1737 /**
1738  * access_remote_vm - access another process' address space
1739  * @mm:         the mm_struct of the target address space
1740  * @addr:       start address to access
1741  * @buf:        source or destination buffer
1742  * @len:        number of bytes to transfer
1743  * @gup_flags:  flags modifying lookup behaviour
1744  *
1745  * The caller must hold a reference on @mm.
1746  */
1747 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
1748                 void *buf, int len, unsigned int gup_flags)
1749 {
1750         return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
1751 }
1752
1753 /*
1754  * Access another process' address space.
1755  * - source/target buffer must be kernel space
1756  */
1757 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
1758                 unsigned int gup_flags)
1759 {
1760         struct mm_struct *mm;
1761
1762         if (addr + len < addr)
1763                 return 0;
1764
1765         mm = get_task_mm(tsk);
1766         if (!mm)
1767                 return 0;
1768
1769         len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
1770
1771         mmput(mm);
1772         return len;
1773 }
1774 EXPORT_SYMBOL_GPL(access_process_vm);
1775
1776 /**
1777  * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1778  * @inode: The inode to check
1779  * @size: The current filesize of the inode
1780  * @newsize: The proposed filesize of the inode
1781  *
1782  * Check the shared mappings on an inode on behalf of a shrinking truncate to
1783  * make sure that that any outstanding VMAs aren't broken and then shrink the
1784  * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
1785  * automatically grant mappings that are too large.
1786  */
1787 int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
1788                                 size_t newsize)
1789 {
1790         struct vm_area_struct *vma;
1791         struct vm_region *region;
1792         pgoff_t low, high;
1793         size_t r_size, r_top;
1794
1795         low = newsize >> PAGE_SHIFT;
1796         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1797
1798         down_write(&nommu_region_sem);
1799         i_mmap_lock_read(inode->i_mapping);
1800
1801         /* search for VMAs that fall within the dead zone */
1802         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
1803                 /* found one - only interested if it's shared out of the page
1804                  * cache */
1805                 if (vma->vm_flags & VM_SHARED) {
1806                         i_mmap_unlock_read(inode->i_mapping);
1807                         up_write(&nommu_region_sem);
1808                         return -ETXTBSY; /* not quite true, but near enough */
1809                 }
1810         }
1811
1812         /* reduce any regions that overlap the dead zone - if in existence,
1813          * these will be pointed to by VMAs that don't overlap the dead zone
1814          *
1815          * we don't check for any regions that start beyond the EOF as there
1816          * shouldn't be any
1817          */
1818         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
1819                 if (!(vma->vm_flags & VM_SHARED))
1820                         continue;
1821
1822                 region = vma->vm_region;
1823                 r_size = region->vm_top - region->vm_start;
1824                 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
1825
1826                 if (r_top > newsize) {
1827                         region->vm_top -= r_top - newsize;
1828                         if (region->vm_end > region->vm_top)
1829                                 region->vm_end = region->vm_top;
1830                 }
1831         }
1832
1833         i_mmap_unlock_read(inode->i_mapping);
1834         up_write(&nommu_region_sem);
1835         return 0;
1836 }
1837
1838 /*
1839  * Initialise sysctl_user_reserve_kbytes.
1840  *
1841  * This is intended to prevent a user from starting a single memory hogging
1842  * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1843  * mode.
1844  *
1845  * The default value is min(3% of free memory, 128MB)
1846  * 128MB is enough to recover with sshd/login, bash, and top/kill.
1847  */
1848 static int __meminit init_user_reserve(void)
1849 {
1850         unsigned long free_kbytes;
1851
1852         free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1853
1854         sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
1855         return 0;
1856 }
1857 subsys_initcall(init_user_reserve);
1858
1859 /*
1860  * Initialise sysctl_admin_reserve_kbytes.
1861  *
1862  * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1863  * to log in and kill a memory hogging process.
1864  *
1865  * Systems with more than 256MB will reserve 8MB, enough to recover
1866  * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1867  * only reserve 3% of free pages by default.
1868  */
1869 static int __meminit init_admin_reserve(void)
1870 {
1871         unsigned long free_kbytes;
1872
1873         free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
1874
1875         sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
1876         return 0;
1877 }
1878 subsys_initcall(init_admin_reserve);