mm/vmalloc.c

   1 /*
   2  *  linux/mm/vmalloc.c
   3  *
   4  *  Copyright (C) 1993  Linus Torvalds
   5  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   6  *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
   7  *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
   8  *  Numa awareness, Christoph Lameter, SGI, June 2005
   9  */
  10
  11 #include <linux/mm.h>
  12 #include <linux/module.h>
  13 #include <linux/highmem.h>
  14 #include <linux/slab.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/interrupt.h>
  17
  18 #include <linux/vmalloc.h>
  19
  20 #include <asm/uaccess.h>
  21 #include <asm/tlbflush.h>
  22
  23
  24 DEFINE_RWLOCK(vmlist_lock);
  25 struct vm_struct *vmlist;
  26
  27 static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
  28                             int node);
  29
  30 static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
  31 {
  32         pte_t *pte;
  33
  34         pte = pte_offset_kernel(pmd, addr);
  35         do {
  36                 pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
  37                 WARN_ON(!pte_none(ptent) && !pte_present(ptent));
  38         } while (pte++, addr += PAGE_SIZE, addr != end);
  39 }
  40
  41 static inline void vunmap_pmd_range(pud_t *pud, unsigned long addr,
  42                                                 unsigned long end)
  43 {
  44         pmd_t *pmd;
  45         unsigned long next;
  46
  47         pmd = pmd_offset(pud, addr);
  48         do {
  49                 next = pmd_addr_end(addr, end);
  50                 if (pmd_none_or_clear_bad(pmd))
  51                         continue;
  52                 vunmap_pte_range(pmd, addr, next);
  53         } while (pmd++, addr = next, addr != end);
  54 }
  55
  56 static inline void vunmap_pud_range(pgd_t *pgd, unsigned long addr,
  57                                                 unsigned long end)
  58 {
  59         pud_t *pud;
  60         unsigned long next;
  61
  62         pud = pud_offset(pgd, addr);
  63         do {
  64                 next = pud_addr_end(addr, end);
  65                 if (pud_none_or_clear_bad(pud))
  66                         continue;
  67                 vunmap_pmd_range(pud, addr, next);
  68         } while (pud++, addr = next, addr != end);
  69 }
  70
  71 void unmap_kernel_range(unsigned long addr, unsigned long size)
  72 {
  73         pgd_t *pgd;
  74         unsigned long next;
  75         unsigned long start = addr;
  76         unsigned long end = addr + size;
  77
  78         BUG_ON(addr >= end);
  79         pgd = pgd_offset_k(addr);
  80         flush_cache_vunmap(addr, end);
  81         do {
  82                 next = pgd_addr_end(addr, end);
  83                 if (pgd_none_or_clear_bad(pgd))
  84                         continue;
  85                 vunmap_pud_range(pgd, addr, next);
  86         } while (pgd++, addr = next, addr != end);
  87         flush_tlb_kernel_range(start, end);
  88 }
  89
  90 static void unmap_vm_area(struct vm_struct *area)
  91 {
  92         unmap_kernel_range((unsigned long)area->addr, area->size);
  93 }
  94
  95 static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
  96                         unsigned long end, pgprot_t prot, struct page ***pages)
  97 {
  98         pte_t *pte;
  99
 100         pte = pte_alloc_kernel(pmd, addr);
 101         if (!pte)
 102                 return -ENOMEM;
 103         do {
 104                 struct page *page = **pages;
 105                 WARN_ON(!pte_none(*pte));
 106                 if (!page)
 107                         return -ENOMEM;
 108                 set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
 109                 (*pages)++;
 110         } while (pte++, addr += PAGE_SIZE, addr != end);
 111         return 0;
 112 }
 113
 114 static inline int vmap_pmd_range(pud_t *pud, unsigned long addr,
 115                         unsigned long end, pgprot_t prot, struct page ***pages)
 116 {
 117         pmd_t *pmd;
 118         unsigned long next;
 119
 120         pmd = pmd_alloc(&init_mm, pud, addr);
 121         if (!pmd)
 122                 return -ENOMEM;
 123         do {
 124                 next = pmd_addr_end(addr, end);
 125                 if (vmap_pte_range(pmd, addr, next, prot, pages))
 126                         return -ENOMEM;
 127         } while (pmd++, addr = next, addr != end);
 128         return 0;
 129 }
 130
 131 static inline int vmap_pud_range(pgd_t *pgd, unsigned long addr,
 132                         unsigned long end, pgprot_t prot, struct page ***pages)
 133 {
 134         pud_t *pud;
 135         unsigned long next;
 136
 137         pud = pud_alloc(&init_mm, pgd, addr);
 138         if (!pud)
 139                 return -ENOMEM;
 140         do {
 141                 next = pud_addr_end(addr, end);
 142                 if (vmap_pmd_range(pud, addr, next, prot, pages))
 143                         return -ENOMEM;
 144         } while (pud++, addr = next, addr != end);
 145         return 0;
 146 }
 147
 148 int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
 149 {
 150         pgd_t *pgd;
 151         unsigned long next;
 152         unsigned long addr = (unsigned long) area->addr;
 153         unsigned long end = addr + area->size - PAGE_SIZE;
 154         int err;
 155
 156         BUG_ON(addr >= end);
 157         pgd = pgd_offset_k(addr);
 158         do {
 159                 next = pgd_addr_end(addr, end);
 160                 err = vmap_pud_range(pgd, addr, next, prot, pages);
 161                 if (err)
 162                         break;
 163         } while (pgd++, addr = next, addr != end);
 164         flush_cache_vmap((unsigned long) area->addr, end);
 165         return err;
 166 }
 167 EXPORT_SYMBOL_GPL(map_vm_area);
 168
 169 /*
 170  * Map a vmalloc()-space virtual address to the physical page.
 171  */
 172 struct page *vmalloc_to_page(const void *vmalloc_addr)
 173 {
 174         unsigned long addr = (unsigned long) vmalloc_addr;
 175         struct page *page = NULL;
 176         pgd_t *pgd = pgd_offset_k(addr);
 177         pud_t *pud;
 178         pmd_t *pmd;
 179         pte_t *ptep, pte;
 180
 181         if (!pgd_none(*pgd)) {
 182                 pud = pud_offset(pgd, addr);
 183                 if (!pud_none(*pud)) {
 184                         pmd = pmd_offset(pud, addr);
 185                         if (!pmd_none(*pmd)) {
 186                                 ptep = pte_offset_map(pmd, addr);
 187                                 pte = *ptep;
 188                                 if (pte_present(pte))
 189                                         page = pte_page(pte);
 190                                 pte_unmap(ptep);
 191                         }
 192                 }
 193         }
 194         return page;
 195 }
 196 EXPORT_SYMBOL(vmalloc_to_page);
 197
 198 /*
 199  * Map a vmalloc()-space virtual address to the physical page frame number.
 200  */
 201 unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
 202 {
 203         return page_to_pfn(vmalloc_to_page(vmalloc_addr));
 204 }
 205 EXPORT_SYMBOL(vmalloc_to_pfn);
 206
 207 static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long flags,
 208                                             unsigned long start, unsigned long end,
 209                                             int node, gfp_t gfp_mask)
 210 {
 211         struct vm_struct **p, *tmp, *area;
 212         unsigned long align = 1;
 213         unsigned long addr;
 214
 215         BUG_ON(in_interrupt());
 216         if (flags & VM_IOREMAP) {
 217                 int bit = fls(size);
 218
 219                 if (bit > IOREMAP_MAX_ORDER)
 220                         bit = IOREMAP_MAX_ORDER;
 221                 else if (bit < PAGE_SHIFT)
 222                         bit = PAGE_SHIFT;
 223
 224                 align = 1ul << bit;
 225         }
 226         addr = ALIGN(start, align);
 227         size = PAGE_ALIGN(size);
 228         if (unlikely(!size))
 229                 return NULL;
 230
 231         area = kmalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
 232
 233         if (unlikely(!area))
 234                 return NULL;
 235
 236         /*
 237          * We always allocate a guard page.
 238          */
 239         size += PAGE_SIZE;
 240
 241         write_lock(&vmlist_lock);
 242         for (p = &vmlist; (tmp = *p) != NULL ;p = &tmp->next) {
 243                 if ((unsigned long)tmp->addr < addr) {
 244                         if((unsigned long)tmp->addr + tmp->size >= addr)
 245                                 addr = ALIGN(tmp->size +
 246                                              (unsigned long)tmp->addr, align);
 247                         continue;
 248                 }
 249                 if ((size + addr) < addr)
 250                         goto out;
 251                 if (size + addr <= (unsigned long)tmp->addr)
 252                         goto found;
 253                 addr = ALIGN(tmp->size + (unsigned long)tmp->addr, align);
 254                 if (addr > end - size)
 255                         goto out;
 256         }
 257         if ((size + addr) < addr)
 258                 goto out;
 259         if (addr > end - size)
 260                 goto out;
 261
 262 found:
 263         area->next = *p;
 264         *p = area;
 265
 266         area->flags = flags;
 267         area->addr = (void *)addr;
 268         area->size = size;
 269         area->pages = NULL;
 270         area->nr_pages = 0;
 271         area->phys_addr = 0;
 272         write_unlock(&vmlist_lock);
 273
 274         return area;
 275
 276 out:
 277         write_unlock(&vmlist_lock);
 278         kfree(area);
 279         if (printk_ratelimit())
 280                 printk(KERN_WARNING "allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.\n");
 281         return NULL;
 282 }
 283
 284 struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
 285                                 unsigned long start, unsigned long end)
 286 {
 287         return __get_vm_area_node(size, flags, start, end, -1, GFP_KERNEL);
 288 }
 289 EXPORT_SYMBOL_GPL(__get_vm_area);
 290
 291 /**
 292  *      get_vm_area  -  reserve a contiguous kernel virtual area
 293  *      @size:          size of the area
 294  *      @flags:         %VM_IOREMAP for I/O mappings or VM_ALLOC
 295  *
 296  *      Search an area of @size in the kernel virtual mapping area,
 297  *      and reserved it for out purposes.  Returns the area descriptor
 298  *      on success or %NULL on failure.
 299  */
 300 struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
 301 {
 302         return __get_vm_area(size, flags, VMALLOC_START, VMALLOC_END);
 303 }
 304
 305 struct vm_struct *get_vm_area_node(unsigned long size, unsigned long flags,
 306                                    int node, gfp_t gfp_mask)
 307 {
 308         return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END, node,
 309                                   gfp_mask);
 310 }
 311
 312 /* Caller must hold vmlist_lock */
 313 static struct vm_struct *__find_vm_area(const void *addr)
 314 {
 315         struct vm_struct *tmp;
 316
 317         for (tmp = vmlist; tmp != NULL; tmp = tmp->next) {
 318                  if (tmp->addr == addr)
 319                         break;
 320         }
 321
 322         return tmp;
 323 }
 324
 325 /* Caller must hold vmlist_lock */
 326 static struct vm_struct *__remove_vm_area(const void *addr)
 327 {
 328         struct vm_struct **p, *tmp;
 329
 330         for (p = &vmlist ; (tmp = *p) != NULL ;p = &tmp->next) {
 331                  if (tmp->addr == addr)
 332                          goto found;
 333         }
 334         return NULL;
 335
 336 found:
 337         unmap_vm_area(tmp);
 338         *p = tmp->next;
 339
 340         /*
 341          * Remove the guard page.
 342          */
 343         tmp->size -= PAGE_SIZE;
 344         return tmp;
 345 }
 346
 347 /**
 348  *      remove_vm_area  -  find and remove a continuous kernel virtual area
 349  *      @addr:          base address
 350  *
 351  *      Search for the kernel VM area starting at @addr, and remove it.
 352  *      This function returns the found VM area, but using it is NOT safe
 353  *      on SMP machines, except for its size or flags.
 354  */
 355 struct vm_struct *remove_vm_area(const void *addr)
 356 {
 357         struct vm_struct *v;
 358         write_lock(&vmlist_lock);
 359         v = __remove_vm_area(addr);
 360         write_unlock(&vmlist_lock);
 361         return v;
 362 }
 363
 364 static void __vunmap(const void *addr, int deallocate_pages)
 365 {
 366         struct vm_struct *area;
 367
 368         if (!addr)
 369                 return;
 370
 371         if ((PAGE_SIZE-1) & (unsigned long)addr) {
 372                 printk(KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
 373                 WARN_ON(1);
 374                 return;
 375         }
 376
 377         area = remove_vm_area(addr);
 378         if (unlikely(!area)) {
 379                 printk(KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
 380                                 addr);
 381                 WARN_ON(1);
 382                 return;
 383         }
 384
 385         debug_check_no_locks_freed(addr, area->size);
 386
 387         if (deallocate_pages) {
 388                 int i;
 389
 390                 for (i = 0; i < area->nr_pages; i++) {
 391                         struct page *page = area->pages[i];
 392
 393                         BUG_ON(!page);
 394                         __free_page(page);
 395                 }
 396
 397                 if (area->flags & VM_VPAGES)
 398                         vfree(area->pages);
 399                 else
 400                         kfree(area->pages);
 401         }
 402
 403         kfree(area);
 404         return;
 405 }
 406
 407 /**
 408  *      vfree  -  release memory allocated by vmalloc()
 409  *      @addr:          memory base address
 410  *
 411  *      Free the virtually continuous memory area starting at @addr, as
 412  *      obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
 413  *      NULL, no operation is performed.
 414  *
 415  *      Must not be called in interrupt context.
 416  */
 417 void vfree(const void *addr)
 418 {
 419         BUG_ON(in_interrupt());
 420         __vunmap(addr, 1);
 421 }
 422 EXPORT_SYMBOL(vfree);
 423
 424 /**
 425  *      vunmap  -  release virtual mapping obtained by vmap()
 426  *      @addr:          memory base address
 427  *
 428  *      Free the virtually contiguous memory area starting at @addr,
 429  *      which was created from the page array passed to vmap().
 430  *
 431  *      Must not be called in interrupt context.
 432  */
 433 void vunmap(const void *addr)
 434 {
 435         BUG_ON(in_interrupt());
 436         __vunmap(addr, 0);
 437 }
 438 EXPORT_SYMBOL(vunmap);
 439
 440 /**
 441  *      vmap  -  map an array of pages into virtually contiguous space
 442  *      @pages:         array of page pointers
 443  *      @count:         number of pages to map
 444  *      @flags:         vm_area->flags
 445  *      @prot:          page protection for the mapping
 446  *
 447  *      Maps @count pages from @pages into contiguous kernel virtual
 448  *      space.
 449  */
 450 void *vmap(struct page **pages, unsigned int count,
 451                 unsigned long flags, pgprot_t prot)
 452 {
 453         struct vm_struct *area;
 454
 455         if (count > num_physpages)
 456                 return NULL;
 457
 458         area = get_vm_area((count << PAGE_SHIFT), flags);
 459         if (!area)
 460                 return NULL;
 461         if (map_vm_area(area, prot, &pages)) {
 462                 vunmap(area->addr);
 463                 return NULL;
 464         }
 465
 466         return area->addr;
 467 }
 468 EXPORT_SYMBOL(vmap);
 469
 470 static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 471                                  pgprot_t prot, int node)
 472 {
 473         struct page **pages;
 474         unsigned int nr_pages, array_size, i;
 475
 476         nr_pages = (area->size - PAGE_SIZE) >> PAGE_SHIFT;
 477         array_size = (nr_pages * sizeof(struct page *));
 478
 479         area->nr_pages = nr_pages;
 480         /* Please note that the recursion is strictly bounded. */
 481         if (array_size > PAGE_SIZE) {
 482                 pages = __vmalloc_node(array_size, gfp_mask | __GFP_ZERO,
 483                                         PAGE_KERNEL, node);
 484                 area->flags |= VM_VPAGES;
 485         } else {
 486                 pages = kmalloc_node(array_size,
 487                                 (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO,
 488                                 node);
 489         }
 490         area->pages = pages;
 491         if (!area->pages) {
 492                 remove_vm_area(area->addr);
 493                 kfree(area);
 494                 return NULL;
 495         }
 496
 497         for (i = 0; i < area->nr_pages; i++) {
 498                 struct page *page;
 499
 500                 if (node < 0)
 501                         page = alloc_page(gfp_mask);
 502                 else
 503                         page = alloc_pages_node(node, gfp_mask, 0);
 504
 505                 if (unlikely(!page)) {
 506                         /* Successfully allocated i pages, free them in __vunmap() */
 507                         area->nr_pages = i;
 508                         goto fail;
 509                 }
 510                 area->pages[i] = page;
 511         }
 512
 513         if (map_vm_area(area, prot, &pages))
 514                 goto fail;
 515         return area->addr;
 516
 517 fail:
 518         vfree(area->addr);
 519         return NULL;
 520 }
 521
 522 void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
 523 {
 524         return __vmalloc_area_node(area, gfp_mask, prot, -1);
 525 }
 526
 527 /**
 528  *      __vmalloc_node  -  allocate virtually contiguous memory
 529  *      @size:          allocation size
 530  *      @gfp_mask:      flags for the page level allocator
 531  *      @prot:          protection mask for the allocated pages
 532  *      @node:          node to use for allocation or -1
 533  *
 534  *      Allocate enough pages to cover @size from the page level
 535  *      allocator with @gfp_mask flags.  Map them into contiguous
 536  *      kernel virtual space, using a pagetable protection of @prot.
 537  */
 538 static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
 539                             int node)
 540 {
 541         struct vm_struct *area;
 542
 543         size = PAGE_ALIGN(size);
 544         if (!size || (size >> PAGE_SHIFT) > num_physpages)
 545                 return NULL;
 546
 547         area = get_vm_area_node(size, VM_ALLOC, node, gfp_mask);
 548         if (!area)
 549                 return NULL;
 550
 551         return __vmalloc_area_node(area, gfp_mask, prot, node);
 552 }
 553
 554 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 555 {
 556         return __vmalloc_node(size, gfp_mask, prot, -1);
 557 }
 558 EXPORT_SYMBOL(__vmalloc);
 559
 560 /**
 561  *      vmalloc  -  allocate virtually contiguous memory
 562  *      @size:          allocation size
 563  *      Allocate enough pages to cover @size from the page level
 564  *      allocator and map them into contiguous kernel virtual space.
 565  *
 566  *      For tight control over page level allocator and protection flags
 567  *      use __vmalloc() instead.
 568  */
 569 void *vmalloc(unsigned long size)
 570 {
 571         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 572 }
 573 EXPORT_SYMBOL(vmalloc);
 574
 575 /**
 576  * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
 577  * @size: allocation size
 578  *
 579  * The resulting memory area is zeroed so it can be mapped to userspace
 580  * without leaking data.
 581  */
 582 void *vmalloc_user(unsigned long size)
 583 {
 584         struct vm_struct *area;
 585         void *ret;
 586
 587         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
 588         if (ret) {
 589                 write_lock(&vmlist_lock);
 590                 area = __find_vm_area(ret);
 591                 area->flags |= VM_USERMAP;
 592                 write_unlock(&vmlist_lock);
 593         }
 594         return ret;
 595 }
 596 EXPORT_SYMBOL(vmalloc_user);
 597
 598 /**
 599  *      vmalloc_node  -  allocate memory on a specific node
 600  *      @size:          allocation size
 601  *      @node:          numa node
 602  *
 603  *      Allocate enough pages to cover @size from the page level
 604  *      allocator and map them into contiguous kernel virtual space.
 605  *
 606  *      For tight control over page level allocator and protection flags
 607  *      use __vmalloc() instead.
 608  */
 609 void *vmalloc_node(unsigned long size, int node)
 610 {
 611         return __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL, node);
 612 }
 613 EXPORT_SYMBOL(vmalloc_node);
 614
 615 #ifndef PAGE_KERNEL_EXEC
 616 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 617 #endif
 618
 619 /**
 620  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 621  *      @size:          allocation size
 622  *
 623  *      Kernel-internal function to allocate enough pages to cover @size
 624  *      the page level allocator and map them into contiguous and
 625  *      executable kernel virtual space.
 626  *
 627  *      For tight control over page level allocator and protection flags
 628  *      use __vmalloc() instead.
 629  */
 630
 631 void *vmalloc_exec(unsigned long size)
 632 {
 633         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 634 }
 635
 636 #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
 637 #define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
 638 #elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
 639 #define GFP_VMALLOC32 GFP_DMA | GFP_KERNEL
 640 #else
 641 #define GFP_VMALLOC32 GFP_KERNEL
 642 #endif
 643
 644 /**
 645  *      vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 646  *      @size:          allocation size
 647  *
 648  *      Allocate enough 32bit PA addressable pages to cover @size from the
 649  *      page level allocator and map them into contiguous kernel virtual space.
 650  */
 651 void *vmalloc_32(unsigned long size)
 652 {
 653         return __vmalloc(size, GFP_VMALLOC32, PAGE_KERNEL);
 654 }
 655 EXPORT_SYMBOL(vmalloc_32);
 656
 657 /**
 658  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 659  *      @size:          allocation size
 660  *
 661  * The resulting memory area is 32bit addressable and zeroed so it can be
 662  * mapped to userspace without leaking data.
 663  */
 664 void *vmalloc_32_user(unsigned long size)
 665 {
 666         struct vm_struct *area;
 667         void *ret;
 668
 669         ret = __vmalloc(size, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL);
 670         if (ret) {
 671                 write_lock(&vmlist_lock);
 672                 area = __find_vm_area(ret);
 673                 area->flags |= VM_USERMAP;
 674                 write_unlock(&vmlist_lock);
 675         }
 676         return ret;
 677 }
 678 EXPORT_SYMBOL(vmalloc_32_user);
 679
 680 long vread(char *buf, char *addr, unsigned long count)
 681 {
 682         struct vm_struct *tmp;
 683         char *vaddr, *buf_start = buf;
 684         unsigned long n;
 685
 686         /* Don't allow overflow */
 687         if ((unsigned long) addr + count < count)
 688                 count = -(unsigned long) addr;
 689
 690         read_lock(&vmlist_lock);
 691         for (tmp = vmlist; tmp; tmp = tmp->next) {
 692                 vaddr = (char *) tmp->addr;
 693                 if (addr >= vaddr + tmp->size - PAGE_SIZE)
 694                         continue;
 695                 while (addr < vaddr) {
 696                         if (count == 0)
 697                                 goto finished;
 698                         *buf = '\0';
 699                         buf++;
 700                         addr++;
 701                         count--;
 702                 }
 703                 n = vaddr + tmp->size - PAGE_SIZE - addr;
 704                 do {
 705                         if (count == 0)
 706                                 goto finished;
 707                         *buf = *addr;
 708                         buf++;
 709                         addr++;
 710                         count--;
 711                 } while (--n > 0);
 712         }
 713 finished:
 714         read_unlock(&vmlist_lock);
 715         return buf - buf_start;
 716 }
 717
 718 long vwrite(char *buf, char *addr, unsigned long count)
 719 {
 720         struct vm_struct *tmp;
 721         char *vaddr, *buf_start = buf;
 722         unsigned long n;
 723
 724         /* Don't allow overflow */
 725         if ((unsigned long) addr + count < count)
 726                 count = -(unsigned long) addr;
 727
 728         read_lock(&vmlist_lock);
 729         for (tmp = vmlist; tmp; tmp = tmp->next) {
 730                 vaddr = (char *) tmp->addr;
 731                 if (addr >= vaddr + tmp->size - PAGE_SIZE)
 732                         continue;
 733                 while (addr < vaddr) {
 734                         if (count == 0)
 735                                 goto finished;
 736                         buf++;
 737                         addr++;
 738                         count--;
 739                 }
 740                 n = vaddr + tmp->size - PAGE_SIZE - addr;
 741                 do {
 742                         if (count == 0)
 743                                 goto finished;
 744                         *addr = *buf;
 745                         buf++;
 746                         addr++;
 747                         count--;
 748                 } while (--n > 0);
 749         }
 750 finished:
 751         read_unlock(&vmlist_lock);
 752         return buf - buf_start;
 753 }
 754
 755 /**
 756  *      remap_vmalloc_range  -  map vmalloc pages to userspace
 757  *      @vma:           vma to cover (map full range of vma)
 758  *      @addr:          vmalloc memory
 759  *      @pgoff:         number of pages into addr before first page to map
 760  *      @returns:       0 for success, -Exxx on failure
 761  *
 762  *      This function checks that addr is a valid vmalloc'ed area, and
 763  *      that it is big enough to cover the vma. Will return failure if
 764  *      that criteria isn't met.
 765  *
 766  *      Similar to remap_pfn_range() (see mm/memory.c)
 767  */
 768 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
 769                                                 unsigned long pgoff)
 770 {
 771         struct vm_struct *area;
 772         unsigned long uaddr = vma->vm_start;
 773         unsigned long usize = vma->vm_end - vma->vm_start;
 774         int ret;
 775
 776         if ((PAGE_SIZE-1) & (unsigned long)addr)
 777                 return -EINVAL;
 778
 779         read_lock(&vmlist_lock);
 780         area = __find_vm_area(addr);
 781         if (!area)
 782                 goto out_einval_locked;
 783
 784         if (!(area->flags & VM_USERMAP))
 785                 goto out_einval_locked;
 786
 787         if (usize + (pgoff << PAGE_SHIFT) > area->size - PAGE_SIZE)
 788                 goto out_einval_locked;
 789         read_unlock(&vmlist_lock);
 790
 791         addr += pgoff << PAGE_SHIFT;
 792         do {
 793                 struct page *page = vmalloc_to_page(addr);
 794                 ret = vm_insert_page(vma, uaddr, page);
 795                 if (ret)
 796                         return ret;
 797
 798                 uaddr += PAGE_SIZE;
 799                 addr += PAGE_SIZE;
 800                 usize -= PAGE_SIZE;
 801         } while (usize > 0);
 802
 803         /* Prevent "things" like memory migration? VM_flags need a cleanup... */
 804         vma->vm_flags |= VM_RESERVED;
 805
 806         return ret;
 807
 808 out_einval_locked:
 809         read_unlock(&vmlist_lock);
 810         return -EINVAL;
 811 }
 812 EXPORT_SYMBOL(remap_vmalloc_range);
 813
 814 /*
 815  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 816  * have one.
 817  */
 818 void  __attribute__((weak)) vmalloc_sync_all(void)
 819 {
 820 }
 821
 822
 823 static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
 824 {
 825         /* apply_to_page_range() does all the hard work. */
 826         return 0;
 827 }
 828
 829 /**
 830  *      alloc_vm_area - allocate a range of kernel address space
 831  *      @size:          size of the area
 832  *      @returns:       NULL on failure, vm_struct on success
 833  *
 834  *      This function reserves a range of kernel address space, and
 835  *      allocates pagetables to map that range.  No actual mappings
 836  *      are created.  If the kernel address space is not shared
 837  *      between processes, it syncs the pagetable across all
 838  *      processes.
 839  */
 840 struct vm_struct *alloc_vm_area(size_t size)
 841 {
 842         struct vm_struct *area;
 843
 844         area = get_vm_area(size, VM_IOREMAP);
 845         if (area == NULL)
 846                 return NULL;
 847
 848         /*
 849          * This ensures that page tables are constructed for this region
 850          * of kernel virtual address space and mapped into init_mm.
 851          */
 852         if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
 853                                 area->size, f, NULL)) {
 854                 free_vm_area(area);
 855                 return NULL;
 856         }
 857
 858         /* Make sure the pagetables are constructed in process kernel
 859            mappings */
 860         vmalloc_sync_all();
 861
 862         return area;
 863 }
 864 EXPORT_SYMBOL_GPL(alloc_vm_area);
 865
 866 void free_vm_area(struct vm_struct *area)
 867 {
 868         struct vm_struct *ret;
 869         ret = remove_vm_area(area->addr);
 870         BUG_ON(ret != area);
 871         kfree(area);
 872 }
 873 EXPORT_SYMBOL_GPL(free_vm_area);