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_vm_area(struct vm_struct *area)
  72 {
  73         pgd_t *pgd;
  74         unsigned long next;
  75         unsigned long addr = (unsigned long) area->addr;
  76         unsigned long end = addr + area->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((unsigned long) area->addr, end);
  88 }
  89
  90 static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
  91                         unsigned long end, pgprot_t prot, struct page ***pages)
  92 {
  93         pte_t *pte;
  94
  95         pte = pte_alloc_kernel(pmd, addr);
  96         if (!pte)
  97                 return -ENOMEM;
  98         do {
  99                 struct page *page = **pages;
 100                 WARN_ON(!pte_none(*pte));
 101                 if (!page)
 102                         return -ENOMEM;
 103                 set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
 104                 (*pages)++;
 105         } while (pte++, addr += PAGE_SIZE, addr != end);
 106         return 0;
 107 }
 108
 109 static inline int vmap_pmd_range(pud_t *pud, unsigned long addr,
 110                         unsigned long end, pgprot_t prot, struct page ***pages)
 111 {
 112         pmd_t *pmd;
 113         unsigned long next;
 114
 115         pmd = pmd_alloc(&init_mm, pud, addr);
 116         if (!pmd)
 117                 return -ENOMEM;
 118         do {
 119                 next = pmd_addr_end(addr, end);
 120                 if (vmap_pte_range(pmd, addr, next, prot, pages))
 121                         return -ENOMEM;
 122         } while (pmd++, addr = next, addr != end);
 123         return 0;
 124 }
 125
 126 static inline int vmap_pud_range(pgd_t *pgd, unsigned long addr,
 127                         unsigned long end, pgprot_t prot, struct page ***pages)
 128 {
 129         pud_t *pud;
 130         unsigned long next;
 131
 132         pud = pud_alloc(&init_mm, pgd, addr);
 133         if (!pud)
 134                 return -ENOMEM;
 135         do {
 136                 next = pud_addr_end(addr, end);
 137                 if (vmap_pmd_range(pud, addr, next, prot, pages))
 138                         return -ENOMEM;
 139         } while (pud++, addr = next, addr != end);
 140         return 0;
 141 }
 142
 143 int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
 144 {
 145         pgd_t *pgd;
 146         unsigned long next;
 147         unsigned long addr = (unsigned long) area->addr;
 148         unsigned long end = addr + area->size - PAGE_SIZE;
 149         int err;
 150
 151         BUG_ON(addr >= end);
 152         pgd = pgd_offset_k(addr);
 153         do {
 154                 next = pgd_addr_end(addr, end);
 155                 err = vmap_pud_range(pgd, addr, next, prot, pages);
 156                 if (err)
 157                         break;
 158         } while (pgd++, addr = next, addr != end);
 159         flush_cache_vmap((unsigned long) area->addr, end);
 160         return err;
 161 }
 162
 163 static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long flags,
 164                                             unsigned long start, unsigned long end,
 165                                             int node, gfp_t gfp_mask)
 166 {
 167         struct vm_struct **p, *tmp, *area;
 168         unsigned long align = 1;
 169         unsigned long addr;
 170
 171         BUG_ON(in_interrupt());
 172         if (flags & VM_IOREMAP) {
 173                 int bit = fls(size);
 174
 175                 if (bit > IOREMAP_MAX_ORDER)
 176                         bit = IOREMAP_MAX_ORDER;
 177                 else if (bit < PAGE_SHIFT)
 178                         bit = PAGE_SHIFT;
 179
 180                 align = 1ul << bit;
 181         }
 182         addr = ALIGN(start, align);
 183         size = PAGE_ALIGN(size);
 184         if (unlikely(!size))
 185                 return NULL;
 186
 187         area = kmalloc_node(sizeof(*area), gfp_mask & GFP_LEVEL_MASK, node);
 188         if (unlikely(!area))
 189                 return NULL;
 190
 191         /*
 192          * We always allocate a guard page.
 193          */
 194         size += PAGE_SIZE;
 195
 196         write_lock(&vmlist_lock);
 197         for (p = &vmlist; (tmp = *p) != NULL ;p = &tmp->next) {
 198                 if ((unsigned long)tmp->addr < addr) {
 199                         if((unsigned long)tmp->addr + tmp->size >= addr)
 200                                 addr = ALIGN(tmp->size +
 201                                              (unsigned long)tmp->addr, align);
 202                         continue;
 203                 }
 204                 if ((size + addr) < addr)
 205                         goto out;
 206                 if (size + addr <= (unsigned long)tmp->addr)
 207                         goto found;
 208                 addr = ALIGN(tmp->size + (unsigned long)tmp->addr, align);
 209                 if (addr > end - size)
 210                         goto out;
 211         }
 212
 213 found:
 214         area->next = *p;
 215         *p = area;
 216
 217         area->flags = flags;
 218         area->addr = (void *)addr;
 219         area->size = size;
 220         area->pages = NULL;
 221         area->nr_pages = 0;
 222         area->phys_addr = 0;
 223         write_unlock(&vmlist_lock);
 224
 225         return area;
 226
 227 out:
 228         write_unlock(&vmlist_lock);
 229         kfree(area);
 230         if (printk_ratelimit())
 231                 printk(KERN_WARNING "allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.\n");
 232         return NULL;
 233 }
 234
 235 struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
 236                                 unsigned long start, unsigned long end)
 237 {
 238         return __get_vm_area_node(size, flags, start, end, -1, GFP_KERNEL);
 239 }
 240
 241 /**
 242  *      get_vm_area  -  reserve a contingous kernel virtual area
 243  *      @size:          size of the area
 244  *      @flags:         %VM_IOREMAP for I/O mappings or VM_ALLOC
 245  *
 246  *      Search an area of @size in the kernel virtual mapping area,
 247  *      and reserved it for out purposes.  Returns the area descriptor
 248  *      on success or %NULL on failure.
 249  */
 250 struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
 251 {
 252         return __get_vm_area(size, flags, VMALLOC_START, VMALLOC_END);
 253 }
 254
 255 struct vm_struct *get_vm_area_node(unsigned long size, unsigned long flags,
 256                                    int node, gfp_t gfp_mask)
 257 {
 258         return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END, node,
 259                                   gfp_mask);
 260 }
 261
 262 /* Caller must hold vmlist_lock */
 263 static struct vm_struct *__find_vm_area(void *addr)
 264 {
 265         struct vm_struct *tmp;
 266
 267         for (tmp = vmlist; tmp != NULL; tmp = tmp->next) {
 268                  if (tmp->addr == addr)
 269                         break;
 270         }
 271
 272         return tmp;
 273 }
 274
 275 /* Caller must hold vmlist_lock */
 276 static struct vm_struct *__remove_vm_area(void *addr)
 277 {
 278         struct vm_struct **p, *tmp;
 279
 280         for (p = &vmlist ; (tmp = *p) != NULL ;p = &tmp->next) {
 281                  if (tmp->addr == addr)
 282                          goto found;
 283         }
 284         return NULL;
 285
 286 found:
 287         unmap_vm_area(tmp);
 288         *p = tmp->next;
 289
 290         /*
 291          * Remove the guard page.
 292          */
 293         tmp->size -= PAGE_SIZE;
 294         return tmp;
 295 }
 296
 297 /**
 298  *      remove_vm_area  -  find and remove a contingous kernel virtual area
 299  *      @addr:          base address
 300  *
 301  *      Search for the kernel VM area starting at @addr, and remove it.
 302  *      This function returns the found VM area, but using it is NOT safe
 303  *      on SMP machines, except for its size or flags.
 304  */
 305 struct vm_struct *remove_vm_area(void *addr)
 306 {
 307         struct vm_struct *v;
 308         write_lock(&vmlist_lock);
 309         v = __remove_vm_area(addr);
 310         write_unlock(&vmlist_lock);
 311         return v;
 312 }
 313
 314 static void __vunmap(void *addr, int deallocate_pages)
 315 {
 316         struct vm_struct *area;
 317
 318         if (!addr)
 319                 return;
 320
 321         if ((PAGE_SIZE-1) & (unsigned long)addr) {
 322                 printk(KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
 323                 WARN_ON(1);
 324                 return;
 325         }
 326
 327         area = remove_vm_area(addr);
 328         if (unlikely(!area)) {
 329                 printk(KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
 330                                 addr);
 331                 WARN_ON(1);
 332                 return;
 333         }
 334
 335         debug_check_no_locks_freed(addr, area->size);
 336
 337         if (deallocate_pages) {
 338                 int i;
 339
 340                 for (i = 0; i < area->nr_pages; i++) {
 341                         BUG_ON(!area->pages[i]);
 342                         __free_page(area->pages[i]);
 343                 }
 344
 345                 if (area->flags & VM_VPAGES)
 346                         vfree(area->pages);
 347                 else
 348                         kfree(area->pages);
 349         }
 350
 351         kfree(area);
 352         return;
 353 }
 354
 355 /**
 356  *      vfree  -  release memory allocated by vmalloc()
 357  *      @addr:          memory base address
 358  *
 359  *      Free the virtually contiguous memory area starting at @addr, as
 360  *      obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
 361  *      NULL, no operation is performed.
 362  *
 363  *      Must not be called in interrupt context.
 364  */
 365 void vfree(void *addr)
 366 {
 367         BUG_ON(in_interrupt());
 368         __vunmap(addr, 1);
 369 }
 370 EXPORT_SYMBOL(vfree);
 371
 372 /**
 373  *      vunmap  -  release virtual mapping obtained by vmap()
 374  *      @addr:          memory base address
 375  *
 376  *      Free the virtually contiguous memory area starting at @addr,
 377  *      which was created from the page array passed to vmap().
 378  *
 379  *      Must not be called in interrupt context.
 380  */
 381 void vunmap(void *addr)
 382 {
 383         BUG_ON(in_interrupt());
 384         __vunmap(addr, 0);
 385 }
 386 EXPORT_SYMBOL(vunmap);
 387
 388 /**
 389  *      vmap  -  map an array of pages into virtually contiguous space
 390  *      @pages:         array of page pointers
 391  *      @count:         number of pages to map
 392  *      @flags:         vm_area->flags
 393  *      @prot:          page protection for the mapping
 394  *
 395  *      Maps @count pages from @pages into contiguous kernel virtual
 396  *      space.
 397  */
 398 void *vmap(struct page **pages, unsigned int count,
 399                 unsigned long flags, pgprot_t prot)
 400 {
 401         struct vm_struct *area;
 402
 403         if (count > num_physpages)
 404                 return NULL;
 405
 406         area = get_vm_area((count << PAGE_SHIFT), flags);
 407         if (!area)
 408                 return NULL;
 409         if (map_vm_area(area, prot, &pages)) {
 410                 vunmap(area->addr);
 411                 return NULL;
 412         }
 413
 414         return area->addr;
 415 }
 416 EXPORT_SYMBOL(vmap);
 417
 418 void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 419                                 pgprot_t prot, int node)
 420 {
 421         struct page **pages;
 422         unsigned int nr_pages, array_size, i;
 423
 424         nr_pages = (area->size - PAGE_SIZE) >> PAGE_SHIFT;
 425         array_size = (nr_pages * sizeof(struct page *));
 426
 427         area->nr_pages = nr_pages;
 428         /* Please note that the recursion is strictly bounded. */
 429         if (array_size > PAGE_SIZE) {
 430                 pages = __vmalloc_node(array_size, gfp_mask, PAGE_KERNEL, node);
 431                 area->flags |= VM_VPAGES;
 432         } else {
 433                 pages = kmalloc_node(array_size,
 434                                 (gfp_mask & GFP_LEVEL_MASK),
 435                                 node);
 436         }
 437         area->pages = pages;
 438         if (!area->pages) {
 439                 remove_vm_area(area->addr);
 440                 kfree(area);
 441                 return NULL;
 442         }
 443         memset(area->pages, 0, array_size);
 444
 445         for (i = 0; i < area->nr_pages; i++) {
 446                 if (node < 0)
 447                         area->pages[i] = alloc_page(gfp_mask);
 448                 else
 449                         area->pages[i] = alloc_pages_node(node, gfp_mask, 0);
 450                 if (unlikely(!area->pages[i])) {
 451                         /* Successfully allocated i pages, free them in __vunmap() */
 452                         area->nr_pages = i;
 453                         goto fail;
 454                 }
 455         }
 456
 457         if (map_vm_area(area, prot, &pages))
 458                 goto fail;
 459         return area->addr;
 460
 461 fail:
 462         vfree(area->addr);
 463         return NULL;
 464 }
 465
 466 void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
 467 {
 468         return __vmalloc_area_node(area, gfp_mask, prot, -1);
 469 }
 470
 471 /**
 472  *      __vmalloc_node  -  allocate virtually contiguous memory
 473  *      @size:          allocation size
 474  *      @gfp_mask:      flags for the page level allocator
 475  *      @prot:          protection mask for the allocated pages
 476  *      @node:          node to use for allocation or -1
 477  *
 478  *      Allocate enough pages to cover @size from the page level
 479  *      allocator with @gfp_mask flags.  Map them into contiguous
 480  *      kernel virtual space, using a pagetable protection of @prot.
 481  */
 482 static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
 483                             int node)
 484 {
 485         struct vm_struct *area;
 486
 487         size = PAGE_ALIGN(size);
 488         if (!size || (size >> PAGE_SHIFT) > num_physpages)
 489                 return NULL;
 490
 491         area = get_vm_area_node(size, VM_ALLOC, node, gfp_mask);
 492         if (!area)
 493                 return NULL;
 494
 495         return __vmalloc_area_node(area, gfp_mask, prot, node);
 496 }
 497
 498 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 499 {
 500         return __vmalloc_node(size, gfp_mask, prot, -1);
 501 }
 502 EXPORT_SYMBOL(__vmalloc);
 503
 504 /**
 505  *      vmalloc  -  allocate virtually contiguous memory
 506  *      @size:          allocation size
 507  *      Allocate enough pages to cover @size from the page level
 508  *      allocator and map them into contiguous kernel virtual space.
 509  *
 510  *      For tight control over page level allocator and protection flags
 511  *      use __vmalloc() instead.
 512  */
 513 void *vmalloc(unsigned long size)
 514 {
 515         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 516 }
 517 EXPORT_SYMBOL(vmalloc);
 518
 519 /**
 520  * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
 521  * @size: allocation size
 522  *
 523  * The resulting memory area is zeroed so it can be mapped to userspace
 524  * without leaking data.
 525  */
 526 void *vmalloc_user(unsigned long size)
 527 {
 528         struct vm_struct *area;
 529         void *ret;
 530
 531         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
 532         if (ret) {
 533                 write_lock(&vmlist_lock);
 534                 area = __find_vm_area(ret);
 535                 area->flags |= VM_USERMAP;
 536                 write_unlock(&vmlist_lock);
 537         }
 538         return ret;
 539 }
 540 EXPORT_SYMBOL(vmalloc_user);
 541
 542 /**
 543  *      vmalloc_node  -  allocate memory on a specific node
 544  *      @size:          allocation size
 545  *      @node:          numa node
 546  *
 547  *      Allocate enough pages to cover @size from the page level
 548  *      allocator and map them into contiguous kernel virtual space.
 549  *
 550  *      For tight control over page level allocator and protection flags
 551  *      use __vmalloc() instead.
 552  */
 553 void *vmalloc_node(unsigned long size, int node)
 554 {
 555         return __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL, node);
 556 }
 557 EXPORT_SYMBOL(vmalloc_node);
 558
 559 #ifndef PAGE_KERNEL_EXEC
 560 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 561 #endif
 562
 563 /**
 564  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 565  *      @size:          allocation size
 566  *
 567  *      Kernel-internal function to allocate enough pages to cover @size
 568  *      the page level allocator and map them into contiguous and
 569  *      executable kernel virtual space.
 570  *
 571  *      For tight control over page level allocator and protection flags
 572  *      use __vmalloc() instead.
 573  */
 574
 575 void *vmalloc_exec(unsigned long size)
 576 {
 577         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 578 }
 579
 580 #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
 581 #define GFP_VMALLOC32 GFP_DMA32
 582 #elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
 583 #define GFP_VMALLOC32 GFP_DMA
 584 #else
 585 #define GFP_VMALLOC32 GFP_KERNEL
 586 #endif
 587
 588 /**
 589  *      vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 590  *      @size:          allocation size
 591  *
 592  *      Allocate enough 32bit PA addressable pages to cover @size from the
 593  *      page level allocator and map them into contiguous kernel virtual space.
 594  */
 595 void *vmalloc_32(unsigned long size)
 596 {
 597         return __vmalloc(size, GFP_VMALLOC32, PAGE_KERNEL);
 598 }
 599 EXPORT_SYMBOL(vmalloc_32);
 600
 601 /**
 602  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 603  *      @size:          allocation size
 604  *
 605  * The resulting memory area is 32bit addressable and zeroed so it can be
 606  * mapped to userspace without leaking data.
 607  */
 608 void *vmalloc_32_user(unsigned long size)
 609 {
 610         struct vm_struct *area;
 611         void *ret;
 612
 613         ret = __vmalloc(size, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL);
 614         if (ret) {
 615                 write_lock(&vmlist_lock);
 616                 area = __find_vm_area(ret);
 617                 area->flags |= VM_USERMAP;
 618                 write_unlock(&vmlist_lock);
 619         }
 620         return ret;
 621 }
 622 EXPORT_SYMBOL(vmalloc_32_user);
 623
 624 long vread(char *buf, char *addr, unsigned long count)
 625 {
 626         struct vm_struct *tmp;
 627         char *vaddr, *buf_start = buf;
 628         unsigned long n;
 629
 630         /* Don't allow overflow */
 631         if ((unsigned long) addr + count < count)
 632                 count = -(unsigned long) addr;
 633
 634         read_lock(&vmlist_lock);
 635         for (tmp = vmlist; tmp; tmp = tmp->next) {
 636                 vaddr = (char *) tmp->addr;
 637                 if (addr >= vaddr + tmp->size - PAGE_SIZE)
 638                         continue;
 639                 while (addr < vaddr) {
 640                         if (count == 0)
 641                                 goto finished;
 642                         *buf = '\0';
 643                         buf++;
 644                         addr++;
 645                         count--;
 646                 }
 647                 n = vaddr + tmp->size - PAGE_SIZE - addr;
 648                 do {
 649                         if (count == 0)
 650                                 goto finished;
 651                         *buf = *addr;
 652                         buf++;
 653                         addr++;
 654                         count--;
 655                 } while (--n > 0);
 656         }
 657 finished:
 658         read_unlock(&vmlist_lock);
 659         return buf - buf_start;
 660 }
 661
 662 long vwrite(char *buf, char *addr, unsigned long count)
 663 {
 664         struct vm_struct *tmp;
 665         char *vaddr, *buf_start = buf;
 666         unsigned long n;
 667
 668         /* Don't allow overflow */
 669         if ((unsigned long) addr + count < count)
 670                 count = -(unsigned long) addr;
 671
 672         read_lock(&vmlist_lock);
 673         for (tmp = vmlist; tmp; tmp = tmp->next) {
 674                 vaddr = (char *) tmp->addr;
 675                 if (addr >= vaddr + tmp->size - PAGE_SIZE)
 676                         continue;
 677                 while (addr < vaddr) {
 678                         if (count == 0)
 679                                 goto finished;
 680                         buf++;
 681                         addr++;
 682                         count--;
 683                 }
 684                 n = vaddr + tmp->size - PAGE_SIZE - addr;
 685                 do {
 686                         if (count == 0)
 687                                 goto finished;
 688                         *addr = *buf;
 689                         buf++;
 690                         addr++;
 691                         count--;
 692                 } while (--n > 0);
 693         }
 694 finished:
 695         read_unlock(&vmlist_lock);
 696         return buf - buf_start;
 697 }
 698
 699 /**
 700  *      remap_vmalloc_range  -  map vmalloc pages to userspace
 701  *      @vma:           vma to cover (map full range of vma)
 702  *      @addr:          vmalloc memory
 703  *      @pgoff:         number of pages into addr before first page to map
 704  *      @returns:       0 for success, -Exxx on failure
 705  *
 706  *      This function checks that addr is a valid vmalloc'ed area, and
 707  *      that it is big enough to cover the vma. Will return failure if
 708  *      that criteria isn't met.
 709  *
 710  *      Similar to remap_pfn_range() (see mm/memory.c)
 711  */
 712 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
 713                                                 unsigned long pgoff)
 714 {
 715         struct vm_struct *area;
 716         unsigned long uaddr = vma->vm_start;
 717         unsigned long usize = vma->vm_end - vma->vm_start;
 718         int ret;
 719
 720         if ((PAGE_SIZE-1) & (unsigned long)addr)
 721                 return -EINVAL;
 722
 723         read_lock(&vmlist_lock);
 724         area = __find_vm_area(addr);
 725         if (!area)
 726                 goto out_einval_locked;
 727
 728         if (!(area->flags & VM_USERMAP))
 729                 goto out_einval_locked;
 730
 731         if (usize + (pgoff << PAGE_SHIFT) > area->size - PAGE_SIZE)
 732                 goto out_einval_locked;
 733         read_unlock(&vmlist_lock);
 734
 735         addr += pgoff << PAGE_SHIFT;
 736         do {
 737                 struct page *page = vmalloc_to_page(addr);
 738                 ret = vm_insert_page(vma, uaddr, page);
 739                 if (ret)
 740                         return ret;
 741
 742                 uaddr += PAGE_SIZE;
 743                 addr += PAGE_SIZE;
 744                 usize -= PAGE_SIZE;
 745         } while (usize > 0);
 746
 747         /* Prevent "things" like memory migration? VM_flags need a cleanup... */
 748         vma->vm_flags |= VM_RESERVED;
 749
 750         return ret;
 751
 752 out_einval_locked:
 753         read_unlock(&vmlist_lock);
 754         return -EINVAL;
 755 }
 756 EXPORT_SYMBOL(remap_vmalloc_range);
 757
 758 /*
 759  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 760  * have one.
 761  */
 762 void  __attribute__((weak)) vmalloc_sync_all(void)
 763 {
 764 }