linux/mm/vmalloc.c
Martin Schwidefsky 2f569afd9c CONFIG_HIGHPTE vs. sub-page page tables.
Background: I've implemented 1K/2K page tables for s390.  These sub-page
page tables are required to properly support the s390 virtualization
instruction with KVM.  The SIE instruction requires that the page tables
have 256 page table entries (pte) followed by 256 page status table entries
(pgste).  The pgstes are only required if the process is using the SIE
instruction.  The pgstes are updated by the hardware and by the hypervisor
for a number of reasons, one of them is dirty and reference bit tracking.
To avoid wasting memory the standard pte table allocation should return
1K/2K (31/64 bit) and 2K/4K if the process is using SIE.

Problem: Page size on s390 is 4K, page table size is 1K or 2K.  That means
the s390 version for pte_alloc_one cannot return a pointer to a struct
page.  Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one
cannot return a pointer to a pte either, since that would require more than
32 bit for the return value of pte_alloc_one (and the pte * would not be
accessible since its not kmapped).

Solution: The only solution I found to this dilemma is a new typedef: a
pgtable_t.  For s390 pgtable_t will be a (pte *) - to be introduced with a
later patch.  For everybody else it will be a (struct page *).  The
additional problem with the initialization of the ptl lock and the
NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and
a destructor pgtable_page_dtor.  The page table allocation and free
functions need to call these two whenever a page table page is allocated or
freed.  pmd_populate will get a pgtable_t instead of a struct page pointer.
 To get the pgtable_t back from a pmd entry that has been installed with
pmd_populate a new function pmd_pgtable is added.  It replaces the pmd_page
call in free_pte_range and apply_to_pte_range.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:42 -08:00

873 lines
20 KiB
C

/*
* linux/mm/vmalloc.c
*
* Copyright (C) 1993 Linus Torvalds
* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
* SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
* Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
* Numa awareness, Christoph Lameter, SGI, June 2005
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/vmalloc.h>
#include <asm/uaccess.h>
#include <asm/tlbflush.h>
DEFINE_RWLOCK(vmlist_lock);
struct vm_struct *vmlist;
static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
int node);
static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
{
pte_t *pte;
pte = pte_offset_kernel(pmd, addr);
do {
pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
WARN_ON(!pte_none(ptent) && !pte_present(ptent));
} while (pte++, addr += PAGE_SIZE, addr != end);
}
static inline void vunmap_pmd_range(pud_t *pud, unsigned long addr,
unsigned long end)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
vunmap_pte_range(pmd, addr, next);
} while (pmd++, addr = next, addr != end);
}
static inline void vunmap_pud_range(pgd_t *pgd, unsigned long addr,
unsigned long end)
{
pud_t *pud;
unsigned long next;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
vunmap_pmd_range(pud, addr, next);
} while (pud++, addr = next, addr != end);
}
void unmap_kernel_range(unsigned long addr, unsigned long size)
{
pgd_t *pgd;
unsigned long next;
unsigned long start = addr;
unsigned long end = addr + size;
BUG_ON(addr >= end);
pgd = pgd_offset_k(addr);
flush_cache_vunmap(addr, end);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
vunmap_pud_range(pgd, addr, next);
} while (pgd++, addr = next, addr != end);
flush_tlb_kernel_range(start, end);
}
static void unmap_vm_area(struct vm_struct *area)
{
unmap_kernel_range((unsigned long)area->addr, area->size);
}
static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, pgprot_t prot, struct page ***pages)
{
pte_t *pte;
pte = pte_alloc_kernel(pmd, addr);
if (!pte)
return -ENOMEM;
do {
struct page *page = **pages;
WARN_ON(!pte_none(*pte));
if (!page)
return -ENOMEM;
set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
(*pages)++;
} while (pte++, addr += PAGE_SIZE, addr != end);
return 0;
}
static inline int vmap_pmd_range(pud_t *pud, unsigned long addr,
unsigned long end, pgprot_t prot, struct page ***pages)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_alloc(&init_mm, pud, addr);
if (!pmd)
return -ENOMEM;
do {
next = pmd_addr_end(addr, end);
if (vmap_pte_range(pmd, addr, next, prot, pages))
return -ENOMEM;
} while (pmd++, addr = next, addr != end);
return 0;
}
static inline int vmap_pud_range(pgd_t *pgd, unsigned long addr,
unsigned long end, pgprot_t prot, struct page ***pages)
{
pud_t *pud;
unsigned long next;
pud = pud_alloc(&init_mm, pgd, addr);
if (!pud)
return -ENOMEM;
do {
next = pud_addr_end(addr, end);
if (vmap_pmd_range(pud, addr, next, prot, pages))
return -ENOMEM;
} while (pud++, addr = next, addr != end);
return 0;
}
int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
{
pgd_t *pgd;
unsigned long next;
unsigned long addr = (unsigned long) area->addr;
unsigned long end = addr + area->size - PAGE_SIZE;
int err;
BUG_ON(addr >= end);
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
err = vmap_pud_range(pgd, addr, next, prot, pages);
if (err)
break;
} while (pgd++, addr = next, addr != end);
flush_cache_vmap((unsigned long) area->addr, end);
return err;
}
EXPORT_SYMBOL_GPL(map_vm_area);
/*
* Map a vmalloc()-space virtual address to the physical page.
*/
struct page *vmalloc_to_page(const void *vmalloc_addr)
{
unsigned long addr = (unsigned long) vmalloc_addr;
struct page *page = NULL;
pgd_t *pgd = pgd_offset_k(addr);
pud_t *pud;
pmd_t *pmd;
pte_t *ptep, pte;
if (!pgd_none(*pgd)) {
pud = pud_offset(pgd, addr);
if (!pud_none(*pud)) {
pmd = pmd_offset(pud, addr);
if (!pmd_none(*pmd)) {
ptep = pte_offset_map(pmd, addr);
pte = *ptep;
if (pte_present(pte))
page = pte_page(pte);
pte_unmap(ptep);
}
}
}
return page;
}
EXPORT_SYMBOL(vmalloc_to_page);
/*
* Map a vmalloc()-space virtual address to the physical page frame number.
*/
unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
{
return page_to_pfn(vmalloc_to_page(vmalloc_addr));
}
EXPORT_SYMBOL(vmalloc_to_pfn);
static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long flags,
unsigned long start, unsigned long end,
int node, gfp_t gfp_mask)
{
struct vm_struct **p, *tmp, *area;
unsigned long align = 1;
unsigned long addr;
BUG_ON(in_interrupt());
if (flags & VM_IOREMAP) {
int bit = fls(size);
if (bit > IOREMAP_MAX_ORDER)
bit = IOREMAP_MAX_ORDER;
else if (bit < PAGE_SHIFT)
bit = PAGE_SHIFT;
align = 1ul << bit;
}
addr = ALIGN(start, align);
size = PAGE_ALIGN(size);
if (unlikely(!size))
return NULL;
area = kmalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
if (unlikely(!area))
return NULL;
/*
* We always allocate a guard page.
*/
size += PAGE_SIZE;
write_lock(&vmlist_lock);
for (p = &vmlist; (tmp = *p) != NULL ;p = &tmp->next) {
if ((unsigned long)tmp->addr < addr) {
if((unsigned long)tmp->addr + tmp->size >= addr)
addr = ALIGN(tmp->size +
(unsigned long)tmp->addr, align);
continue;
}
if ((size + addr) < addr)
goto out;
if (size + addr <= (unsigned long)tmp->addr)
goto found;
addr = ALIGN(tmp->size + (unsigned long)tmp->addr, align);
if (addr > end - size)
goto out;
}
if ((size + addr) < addr)
goto out;
if (addr > end - size)
goto out;
found:
area->next = *p;
*p = area;
area->flags = flags;
area->addr = (void *)addr;
area->size = size;
area->pages = NULL;
area->nr_pages = 0;
area->phys_addr = 0;
write_unlock(&vmlist_lock);
return area;
out:
write_unlock(&vmlist_lock);
kfree(area);
if (printk_ratelimit())
printk(KERN_WARNING "allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.\n");
return NULL;
}
struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
unsigned long start, unsigned long end)
{
return __get_vm_area_node(size, flags, start, end, -1, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(__get_vm_area);
/**
* get_vm_area - reserve a contiguous kernel virtual area
* @size: size of the area
* @flags: %VM_IOREMAP for I/O mappings or VM_ALLOC
*
* Search an area of @size in the kernel virtual mapping area,
* and reserved it for out purposes. Returns the area descriptor
* on success or %NULL on failure.
*/
struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
{
return __get_vm_area(size, flags, VMALLOC_START, VMALLOC_END);
}
struct vm_struct *get_vm_area_node(unsigned long size, unsigned long flags,
int node, gfp_t gfp_mask)
{
return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END, node,
gfp_mask);
}
/* Caller must hold vmlist_lock */
static struct vm_struct *__find_vm_area(const void *addr)
{
struct vm_struct *tmp;
for (tmp = vmlist; tmp != NULL; tmp = tmp->next) {
if (tmp->addr == addr)
break;
}
return tmp;
}
/* Caller must hold vmlist_lock */
static struct vm_struct *__remove_vm_area(const void *addr)
{
struct vm_struct **p, *tmp;
for (p = &vmlist ; (tmp = *p) != NULL ;p = &tmp->next) {
if (tmp->addr == addr)
goto found;
}
return NULL;
found:
unmap_vm_area(tmp);
*p = tmp->next;
/*
* Remove the guard page.
*/
tmp->size -= PAGE_SIZE;
return tmp;
}
/**
* remove_vm_area - find and remove a continuous kernel virtual area
* @addr: base address
*
* Search for the kernel VM area starting at @addr, and remove it.
* This function returns the found VM area, but using it is NOT safe
* on SMP machines, except for its size or flags.
*/
struct vm_struct *remove_vm_area(const void *addr)
{
struct vm_struct *v;
write_lock(&vmlist_lock);
v = __remove_vm_area(addr);
write_unlock(&vmlist_lock);
return v;
}
static void __vunmap(const void *addr, int deallocate_pages)
{
struct vm_struct *area;
if (!addr)
return;
if ((PAGE_SIZE-1) & (unsigned long)addr) {
printk(KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
WARN_ON(1);
return;
}
area = remove_vm_area(addr);
if (unlikely(!area)) {
printk(KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
addr);
WARN_ON(1);
return;
}
debug_check_no_locks_freed(addr, area->size);
if (deallocate_pages) {
int i;
for (i = 0; i < area->nr_pages; i++) {
struct page *page = area->pages[i];
BUG_ON(!page);
__free_page(page);
}
if (area->flags & VM_VPAGES)
vfree(area->pages);
else
kfree(area->pages);
}
kfree(area);
return;
}
/**
* vfree - release memory allocated by vmalloc()
* @addr: memory base address
*
* Free the virtually continuous memory area starting at @addr, as
* obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
* NULL, no operation is performed.
*
* Must not be called in interrupt context.
*/
void vfree(const void *addr)
{
BUG_ON(in_interrupt());
__vunmap(addr, 1);
}
EXPORT_SYMBOL(vfree);
/**
* vunmap - release virtual mapping obtained by vmap()
* @addr: memory base address
*
* Free the virtually contiguous memory area starting at @addr,
* which was created from the page array passed to vmap().
*
* Must not be called in interrupt context.
*/
void vunmap(const void *addr)
{
BUG_ON(in_interrupt());
__vunmap(addr, 0);
}
EXPORT_SYMBOL(vunmap);
/**
* vmap - map an array of pages into virtually contiguous space
* @pages: array of page pointers
* @count: number of pages to map
* @flags: vm_area->flags
* @prot: page protection for the mapping
*
* Maps @count pages from @pages into contiguous kernel virtual
* space.
*/
void *vmap(struct page **pages, unsigned int count,
unsigned long flags, pgprot_t prot)
{
struct vm_struct *area;
if (count > num_physpages)
return NULL;
area = get_vm_area((count << PAGE_SHIFT), flags);
if (!area)
return NULL;
if (map_vm_area(area, prot, &pages)) {
vunmap(area->addr);
return NULL;
}
return area->addr;
}
EXPORT_SYMBOL(vmap);
static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
pgprot_t prot, int node)
{
struct page **pages;
unsigned int nr_pages, array_size, i;
nr_pages = (area->size - PAGE_SIZE) >> PAGE_SHIFT;
array_size = (nr_pages * sizeof(struct page *));
area->nr_pages = nr_pages;
/* Please note that the recursion is strictly bounded. */
if (array_size > PAGE_SIZE) {
pages = __vmalloc_node(array_size, gfp_mask | __GFP_ZERO,
PAGE_KERNEL, node);
area->flags |= VM_VPAGES;
} else {
pages = kmalloc_node(array_size,
(gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO,
node);
}
area->pages = pages;
if (!area->pages) {
remove_vm_area(area->addr);
kfree(area);
return NULL;
}
for (i = 0; i < area->nr_pages; i++) {
struct page *page;
if (node < 0)
page = alloc_page(gfp_mask);
else
page = alloc_pages_node(node, gfp_mask, 0);
if (unlikely(!page)) {
/* Successfully allocated i pages, free them in __vunmap() */
area->nr_pages = i;
goto fail;
}
area->pages[i] = page;
}
if (map_vm_area(area, prot, &pages))
goto fail;
return area->addr;
fail:
vfree(area->addr);
return NULL;
}
void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
{
return __vmalloc_area_node(area, gfp_mask, prot, -1);
}
/**
* __vmalloc_node - allocate virtually contiguous memory
* @size: allocation size
* @gfp_mask: flags for the page level allocator
* @prot: protection mask for the allocated pages
* @node: node to use for allocation or -1
*
* Allocate enough pages to cover @size from the page level
* allocator with @gfp_mask flags. Map them into contiguous
* kernel virtual space, using a pagetable protection of @prot.
*/
static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
int node)
{
struct vm_struct *area;
size = PAGE_ALIGN(size);
if (!size || (size >> PAGE_SHIFT) > num_physpages)
return NULL;
area = get_vm_area_node(size, VM_ALLOC, node, gfp_mask);
if (!area)
return NULL;
return __vmalloc_area_node(area, gfp_mask, prot, node);
}
void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
{
return __vmalloc_node(size, gfp_mask, prot, -1);
}
EXPORT_SYMBOL(__vmalloc);
/**
* vmalloc - allocate virtually contiguous memory
* @size: allocation size
* Allocate enough pages to cover @size from the page level
* allocator and map them into contiguous kernel virtual space.
*
* For tight control over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vmalloc(unsigned long size)
{
return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
}
EXPORT_SYMBOL(vmalloc);
/**
* vmalloc_user - allocate zeroed virtually contiguous memory for userspace
* @size: allocation size
*
* The resulting memory area is zeroed so it can be mapped to userspace
* without leaking data.
*/
void *vmalloc_user(unsigned long size)
{
struct vm_struct *area;
void *ret;
ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
if (ret) {
write_lock(&vmlist_lock);
area = __find_vm_area(ret);
area->flags |= VM_USERMAP;
write_unlock(&vmlist_lock);
}
return ret;
}
EXPORT_SYMBOL(vmalloc_user);
/**
* vmalloc_node - allocate memory on a specific node
* @size: allocation size
* @node: numa node
*
* Allocate enough pages to cover @size from the page level
* allocator and map them into contiguous kernel virtual space.
*
* For tight control over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vmalloc_node(unsigned long size, int node)
{
return __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL, node);
}
EXPORT_SYMBOL(vmalloc_node);
#ifndef PAGE_KERNEL_EXEC
# define PAGE_KERNEL_EXEC PAGE_KERNEL
#endif
/**
* vmalloc_exec - allocate virtually contiguous, executable memory
* @size: allocation size
*
* Kernel-internal function to allocate enough pages to cover @size
* the page level allocator and map them into contiguous and
* executable kernel virtual space.
*
* For tight control over page level allocator and protection flags
* use __vmalloc() instead.
*/
void *vmalloc_exec(unsigned long size)
{
return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
}
#if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
#define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
#define GFP_VMALLOC32 GFP_DMA | GFP_KERNEL
#else
#define GFP_VMALLOC32 GFP_KERNEL
#endif
/**
* vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
* @size: allocation size
*
* Allocate enough 32bit PA addressable pages to cover @size from the
* page level allocator and map them into contiguous kernel virtual space.
*/
void *vmalloc_32(unsigned long size)
{
return __vmalloc(size, GFP_VMALLOC32, PAGE_KERNEL);
}
EXPORT_SYMBOL(vmalloc_32);
/**
* vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
* @size: allocation size
*
* The resulting memory area is 32bit addressable and zeroed so it can be
* mapped to userspace without leaking data.
*/
void *vmalloc_32_user(unsigned long size)
{
struct vm_struct *area;
void *ret;
ret = __vmalloc(size, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL);
if (ret) {
write_lock(&vmlist_lock);
area = __find_vm_area(ret);
area->flags |= VM_USERMAP;
write_unlock(&vmlist_lock);
}
return ret;
}
EXPORT_SYMBOL(vmalloc_32_user);
long vread(char *buf, char *addr, unsigned long count)
{
struct vm_struct *tmp;
char *vaddr, *buf_start = buf;
unsigned long n;
/* Don't allow overflow */
if ((unsigned long) addr + count < count)
count = -(unsigned long) addr;
read_lock(&vmlist_lock);
for (tmp = vmlist; tmp; tmp = tmp->next) {
vaddr = (char *) tmp->addr;
if (addr >= vaddr + tmp->size - PAGE_SIZE)
continue;
while (addr < vaddr) {
if (count == 0)
goto finished;
*buf = '\0';
buf++;
addr++;
count--;
}
n = vaddr + tmp->size - PAGE_SIZE - addr;
do {
if (count == 0)
goto finished;
*buf = *addr;
buf++;
addr++;
count--;
} while (--n > 0);
}
finished:
read_unlock(&vmlist_lock);
return buf - buf_start;
}
long vwrite(char *buf, char *addr, unsigned long count)
{
struct vm_struct *tmp;
char *vaddr, *buf_start = buf;
unsigned long n;
/* Don't allow overflow */
if ((unsigned long) addr + count < count)
count = -(unsigned long) addr;
read_lock(&vmlist_lock);
for (tmp = vmlist; tmp; tmp = tmp->next) {
vaddr = (char *) tmp->addr;
if (addr >= vaddr + tmp->size - PAGE_SIZE)
continue;
while (addr < vaddr) {
if (count == 0)
goto finished;
buf++;
addr++;
count--;
}
n = vaddr + tmp->size - PAGE_SIZE - addr;
do {
if (count == 0)
goto finished;
*addr = *buf;
buf++;
addr++;
count--;
} while (--n > 0);
}
finished:
read_unlock(&vmlist_lock);
return buf - buf_start;
}
/**
* remap_vmalloc_range - map vmalloc pages to userspace
* @vma: vma to cover (map full range of vma)
* @addr: vmalloc memory
* @pgoff: number of pages into addr before first page to map
* @returns: 0 for success, -Exxx on failure
*
* This function checks that addr is a valid vmalloc'ed area, and
* that it is big enough to cover the vma. Will return failure if
* that criteria isn't met.
*
* Similar to remap_pfn_range() (see mm/memory.c)
*/
int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
unsigned long pgoff)
{
struct vm_struct *area;
unsigned long uaddr = vma->vm_start;
unsigned long usize = vma->vm_end - vma->vm_start;
int ret;
if ((PAGE_SIZE-1) & (unsigned long)addr)
return -EINVAL;
read_lock(&vmlist_lock);
area = __find_vm_area(addr);
if (!area)
goto out_einval_locked;
if (!(area->flags & VM_USERMAP))
goto out_einval_locked;
if (usize + (pgoff << PAGE_SHIFT) > area->size - PAGE_SIZE)
goto out_einval_locked;
read_unlock(&vmlist_lock);
addr += pgoff << PAGE_SHIFT;
do {
struct page *page = vmalloc_to_page(addr);
ret = vm_insert_page(vma, uaddr, page);
if (ret)
return ret;
uaddr += PAGE_SIZE;
addr += PAGE_SIZE;
usize -= PAGE_SIZE;
} while (usize > 0);
/* Prevent "things" like memory migration? VM_flags need a cleanup... */
vma->vm_flags |= VM_RESERVED;
return ret;
out_einval_locked:
read_unlock(&vmlist_lock);
return -EINVAL;
}
EXPORT_SYMBOL(remap_vmalloc_range);
/*
* Implement a stub for vmalloc_sync_all() if the architecture chose not to
* have one.
*/
void __attribute__((weak)) vmalloc_sync_all(void)
{
}
static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
{
/* apply_to_page_range() does all the hard work. */
return 0;
}
/**
* alloc_vm_area - allocate a range of kernel address space
* @size: size of the area
* @returns: NULL on failure, vm_struct on success
*
* This function reserves a range of kernel address space, and
* allocates pagetables to map that range. No actual mappings
* are created. If the kernel address space is not shared
* between processes, it syncs the pagetable across all
* processes.
*/
struct vm_struct *alloc_vm_area(size_t size)
{
struct vm_struct *area;
area = get_vm_area(size, VM_IOREMAP);
if (area == NULL)
return NULL;
/*
* This ensures that page tables are constructed for this region
* of kernel virtual address space and mapped into init_mm.
*/
if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
area->size, f, NULL)) {
free_vm_area(area);
return NULL;
}
/* Make sure the pagetables are constructed in process kernel
mappings */
vmalloc_sync_all();
return area;
}
EXPORT_SYMBOL_GPL(alloc_vm_area);
void free_vm_area(struct vm_struct *area)
{
struct vm_struct *ret;
ret = remove_vm_area(area->addr);
BUG_ON(ret != area);
kfree(area);
}
EXPORT_SYMBOL_GPL(free_vm_area);