- 根目录:
- arch
- arm
- plat-omap
- iovmm.c
/*
* omap iommu: simple virtual address space management
*
* Copyright (C) 2008-2009 Nokia Corporation
*
* Written by Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/device.h>
#include <linux/scatterlist.h>
#include <asm/cacheflush.h>
#include <asm/mach/map.h>
#include <plat/iommu.h>
#include <plat/iovmm.h>
#include "iopgtable.h"
/*
* A device driver needs to create address mappings between:
*
* - iommu/device address
* - physical address
* - mpu virtual address
*
* There are 4 possible patterns for them:
*
* |iova/ mapping iommu_ page
* | da pa va (d)-(p)-(v) function type
* ---------------------------------------------------------------------------
* 1 | c c c 1 - 1 - 1 _kmap() / _kunmap() s
* 2 | c c,a c 1 - 1 - 1 _kmalloc()/ _kfree() s
* 3 | c d c 1 - n - 1 _vmap() / _vunmap() s
* 4 | c d,a c 1 - n - 1 _vmalloc()/ _vfree() n*
*
*
* 'iova': device iommu virtual address
* 'da': alias of 'iova'
* 'pa': physical address
* 'va': mpu virtual address
*
* 'c': contiguous memory area
* 'd': discontiguous memory area
* 'a': anonymous memory allocation
* '()': optional feature
*
* 'n': a normal page(4KB) size is used.
* 's': multiple iommu superpage(16MB, 1MB, 64KB, 4KB) size is used.
*
* '*': not yet, but feasible.
*/
static struct kmem_cache *iovm_area_cachep;
/* return total bytes of sg buffers */
static size_t sgtable_len(const struct sg_table *sgt)
{
unsigned int i, total = 0;
struct scatterlist *sg;
if (!sgt)
return 0;
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
size_t bytes;
bytes = sg_dma_len(sg);
if (!iopgsz_ok(bytes)) {
pr_err("%s: sg[%d] not iommu pagesize(%x)\n",
__func__, i, bytes);
return 0;
}
total += bytes;
}
return total;
}
#define sgtable_ok(x) (!!sgtable_len(x))
static unsigned max_alignment(u32 addr)
{
int i;
unsigned pagesize[] = { SZ_16M, SZ_1M, SZ_64K, SZ_4K, };
for (i = 0; i < ARRAY_SIZE(pagesize) && addr & (pagesize[i] - 1); i++)
;
return (i < ARRAY_SIZE(pagesize)) ? pagesize[i] : 0;
}
/*
* calculate the optimal number sg elements from total bytes based on
* iommu superpages
*/
static unsigned sgtable_nents(size_t bytes, u32 da, u32 pa)
{
unsigned nr_entries = 0, ent_sz;
if (!IS_ALIGNED(bytes, PAGE_SIZE)) {
pr_err("%s: wrong size %08x\n", __func__, bytes);
return 0;
}
while (bytes) {
ent_sz = max_alignment(da | pa);
ent_sz = min_t(unsigned, ent_sz, iopgsz_max(bytes));
nr_entries++;
da += ent_sz;
pa += ent_sz;
bytes -= ent_sz;
}
return nr_entries;
}
/* allocate and initialize sg_table header(a kind of 'superblock') */
static struct sg_table *sgtable_alloc(const size_t bytes, u32 flags,
u32 da, u32 pa)
{
unsigned int nr_entries;
int err;
struct sg_table *sgt;
if (!bytes)
return ERR_PTR(-EINVAL);
if (!IS_ALIGNED(bytes, PAGE_SIZE))
return ERR_PTR(-EINVAL);
if (flags & IOVMF_LINEAR) {
nr_entries = sgtable_nents(bytes, da, pa);
if (!nr_entries)
return ERR_PTR(-EINVAL);
} else
nr_entries = bytes / PAGE_SIZE;
sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
if (!sgt)
return ERR_PTR(-ENOMEM);
err = sg_alloc_table(sgt, nr_entries, GFP_KERNEL);
if (err) {
kfree(sgt);
return ERR_PTR(err);
}
pr_debug("%s: sgt:%p(%d entries)\n", __func__, sgt, nr_entries);
return sgt;
}
/* free sg_table header(a kind of superblock) */
static void sgtable_free(struct sg_table *sgt)
{
if (!sgt)
return;
sg_free_table(sgt);
kfree(sgt);
pr_debug("%s: sgt:%p\n", __func__, sgt);
}
/* map 'sglist' to a contiguous mpu virtual area and return 'va' */
static void *vmap_sg(const struct sg_table *sgt)
{
u32 va;
size_t total;
unsigned int i;
struct scatterlist *sg;
struct vm_struct *new;
const struct mem_type *mtype;
mtype = get_mem_type(MT_DEVICE);
if (!mtype)
return ERR_PTR(-EINVAL);
total = sgtable_len(sgt);
if (!total)
return ERR_PTR(-EINVAL);
new = __get_vm_area(total, VM_IOREMAP, VMALLOC_START, VMALLOC_END);
if (!new)
return ERR_PTR(-ENOMEM);
va = (u32)new->addr;
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
size_t bytes;
u32 pa;
int err;
pa = sg_phys(sg);
bytes = sg_dma_len(sg);
BUG_ON(bytes != PAGE_SIZE);
err = ioremap_page(va, pa, mtype);
if (err)
goto err_out;
va += bytes;
}
flush_cache_vmap((unsigned long)new->addr,
(unsigned long)(new->addr + total));
return new->addr;
err_out:
WARN_ON(1); /* FIXME: cleanup some mpu mappings */
vunmap(new->addr);
return ERR_PTR(-EAGAIN);
}
static inline void vunmap_sg(const void *va)
{
vunmap(va);
}
static struct iovm_struct *__find_iovm_area(struct iommu *obj, const u32 da)
{
struct iovm_struct *tmp;
list_for_each_entry(tmp, &obj->mmap, list) {
if ((da >= tmp->da_start) && (da < tmp->da_end)) {
size_t len;
len = tmp->da_end - tmp->da_start;
dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n",
__func__, tmp->da_start, da, tmp->da_end, len,
tmp->flags);
return tmp;
}
}
return NULL;
}
/**
* find_iovm_area - find iovma which includes @da
* @da: iommu device virtual address
*
* Find the existing iovma starting at @da
*/
struct iovm_struct *find_iovm_area(struct iommu *obj, u32 da)
{
struct iovm_struct *area;
mutex_lock(&obj->mmap_lock);
area = __find_iovm_area(obj, da);
mutex_unlock(&obj->mmap_lock);
return area;
}
EXPORT_SYMBOL_GPL(find_iovm_area);
/*
* This finds the hole(area) which fits the requested address and len
* in iovmas mmap, and returns the new allocated iovma.
*/
static struct iovm_struct *alloc_iovm_area(struct iommu *obj, u32 da,
size_t bytes, u32 flags)
{
struct iovm_struct *new, *tmp;
u32 start, prev_end, alignment;
if (!obj || !bytes)
return ERR_PTR(-EINVAL);
start = da;
alignment = PAGE_SIZE;
if (~flags & IOVMF_DA_FIXED) {
/* Don't map address 0 */
start = obj->da_start ? obj->da_start : alignment;
if (flags & IOVMF_LINEAR)
alignment = iopgsz_max(bytes);
start = roundup(start, alignment);
} else if (start < obj->da_start || start > obj->da_end ||
obj->da_end - start < bytes) {
return ERR_PTR(-EINVAL);
}
tmp = NULL;
if (list_empty(&obj->mmap))
goto found;
prev_end = 0;
list_for_each_entry(tmp, &obj->mmap, list) {
if (prev_end > start)
break;
if (tmp->da_start > start && (tmp->da_start - start) >= bytes)
goto found;
if (tmp->da_end >= start && ~flags & IOVMF_DA_FIXED)
start = roundup(tmp->da_end + 1, alignment);
prev_end = tmp->da_end;
}
if ((start >= prev_end) && (obj->da_end - start >= bytes))
goto found;
dev_dbg(obj->dev, "%s: no space to fit %08x(%x) flags: %08x\n",
__func__, da, bytes, flags);
return ERR_PTR(-EINVAL);
found:
new = kmem_cache_zalloc(iovm_area_cachep, GFP_KERNEL);
if (!new)
return ERR_PTR(-ENOMEM);
new->iommu = obj;
new->da_start = start;
new->da_end = start + bytes;
new->flags = flags;
/*
* keep ascending order of iovmas
*/
if (tmp)
list_add_tail(&new->list, &tmp->list);
else
list_add(&new->list, &obj->mmap);
dev_dbg(obj->dev, "%s: found %08x-%08x-%08x(%x) %08x\n",
__func__, new->da_start, start, new->da_end, bytes, flags);
return new;
}
static void free_iovm_area(struct iommu *obj, struct iovm_struct *area)
{
size_t bytes;
BUG_ON(!obj || !area);
bytes = area->da_end - area->da_start;
dev_dbg(obj->dev, "%s: %08x-%08x(%x) %08x\n",
__func__, area->da_start, area->da_end, bytes, area->flags);
list_del(&area->list);
kmem_cache_free(iovm_area_cachep, area);
}
/**
* da_to_va - convert (d) to (v)
* @obj: objective iommu
* @da: iommu device virtual address
* @va: mpu virtual address
*
* Returns mpu virtual addr which corresponds to a given device virtual addr
*/
void *da_to_va(struct iommu *obj, u32 da)
{
void *va = NULL;
struct iovm_struct *area;
mutex_lock(&obj->mmap_lock);
area = __find_iovm_area(obj, da);
if (!area) {
dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
goto out;
}
va = area->va;
out:
mutex_unlock(&obj->mmap_lock);
return va;
}
EXPORT_SYMBOL_GPL(da_to_va);
static void sgtable_fill_vmalloc(struct sg_table *sgt, void *_va)
{
unsigned int i;
struct scatterlist *sg;
void *va = _va;
void *va_end;
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
struct page *pg;
const size_t bytes = PAGE_SIZE;
/*
* iommu 'superpage' isn't supported with 'iommu_vmalloc()'
*/
pg = vmalloc_to_page(va);
BUG_ON(!pg);
sg_set_page(sg, pg, bytes, 0);
va += bytes;
}
va_end = _va + PAGE_SIZE * i;
}
static inline void sgtable_drain_vmalloc(struct sg_table *sgt)
{
/*
* Actually this is not necessary at all, just exists for
* consistency of the code readability.
*/
BUG_ON(!sgt);
}
static void sgtable_fill_kmalloc(struct sg_table *sgt, u32 pa, u32 da,
size_t len)
{
unsigned int i;
struct scatterlist *sg;
void *va;
va = phys_to_virt(pa);
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
unsigned bytes;
bytes = max_alignment(da | pa);
bytes = min_t(unsigned, bytes, iopgsz_max(len));
BUG_ON(!iopgsz_ok(bytes));
sg_set_buf(sg, phys_to_virt(pa), bytes);
/*
* 'pa' is cotinuous(linear).
*/
pa += bytes;
da += bytes;
len -= bytes;
}
BUG_ON(len);
}
static inline void sgtable_drain_kmalloc(struct sg_table *sgt)
{
/*
* Actually this is not necessary at all, just exists for
* consistency of the code readability
*/
BUG_ON(!sgt);
}
/* create 'da' <-> 'pa' mapping from 'sgt' */
static int map_iovm_area(struct iommu *obj, struct iovm_struct *new,
const struct sg_table *sgt, u32 flags)
{
int err;
unsigned int i, j;
struct scatterlist *sg;
u32 da = new->da_start;
if (!obj || !sgt)
return -EINVAL;
BUG_ON(!sgtable_ok(sgt));
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
u32 pa;
int pgsz;
size_t bytes;
struct iotlb_entry e;
pa = sg_phys(sg);
bytes = sg_dma_len(sg);
flags &= ~IOVMF_PGSZ_MASK;
pgsz = bytes_to_iopgsz(bytes);
if (pgsz < 0)
goto err_out;
flags |= pgsz;
pr_debug("%s: [%d] %08x %08x(%x)\n", __func__,
i, da, pa, bytes);
iotlb_init_entry(&e, da, pa, flags);
err = iopgtable_store_entry(obj, &e);
if (err)
goto err_out;
da += bytes;
}
return 0;
err_out:
da = new->da_start;
for_each_sg(sgt->sgl, sg, i, j) {
size_t bytes;
bytes = iopgtable_clear_entry(obj, da);
BUG_ON(!iopgsz_ok(bytes));
da += bytes;
}
return err;
}
/* release 'da' <-> 'pa' mapping */
static void unmap_iovm_area(struct iommu *obj, struct iovm_struct *area)
{
u32 start;
size_t total = area->da_end - area->da_start;
BUG_ON((!total) || !IS_ALIGNED(total, PAGE_SIZE));
start = area->da_start;
while (total > 0) {
size_t bytes;
bytes = iopgtable_clear_entry(obj, start);
if (bytes == 0)
bytes = PAGE_SIZE;
else
dev_dbg(obj->dev, "%s: unmap %08x(%x) %08x\n",
__func__, start, bytes, area->flags);
BUG_ON(!IS_ALIGNED(bytes, PAGE_SIZE));
total -= bytes;
start += bytes;
}
BUG_ON(total);
}
/* template function for all unmapping */
static struct sg_table *unmap_vm_area(struct iommu *obj, const u32 da,
void (*fn)(const void *), u32 flags)
{
struct sg_table *sgt = NULL;
struct iovm_struct *area;
if (!IS_ALIGNED(da, PAGE_SIZE)) {
dev_err(obj->dev, "%s: alignment err(%08x)\n", __func__, da);
return NULL;
}
mutex_lock(&obj->mmap_lock);
area = __find_iovm_area(obj, da);
if (!area) {
dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
goto out;
}
if ((area->flags & flags) != flags) {
dev_err(obj->dev, "%s: wrong flags(%08x)\n", __func__,
area->flags);
goto out;
}
sgt = (struct sg_table *)area->sgt;
unmap_iovm_area(obj, area);
fn(area->va);
dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n", __func__,
area->da_start, da, area->da_end,
area->da_end - area->da_start, area->flags);
free_iovm_area(obj, area);
out:
mutex_unlock(&obj->mmap_lock);
return sgt;
}
static u32 map_iommu_region(struct iommu *obj, u32 da,
const struct sg_table *sgt, void *va, size_t bytes, u32 flags)
{
int err = -ENOMEM;
struct iovm_struct *new;
mutex_lock(&obj->mmap_lock);
new = alloc_iovm_area(obj, da, bytes, flags);
if (IS_ERR(new)) {
err = PTR_ERR(new);
goto err_alloc_iovma;
}
new->va = va;
new->sgt = sgt;
if (map_iovm_area(obj, new, sgt, new->flags))
goto err_map;
mutex_unlock(&obj->mmap_lock);
dev_dbg(obj->dev, "%s: da:%08x(%x) flags:%08x va:%p\n",
__func__, new->da_start, bytes, new->flags, va);
return new->da_start;
err_map:
free_iovm_area(obj, new);
err_alloc_iovma:
mutex_unlock(&obj->mmap_lock);
return err;
}
static inline u32 __iommu_vmap(struct iommu *obj, u32 da,
const struct sg_table *sgt, void *va, size_t bytes, u32 flags)
{
return map_iommu_region(obj, da, sgt, va, bytes, flags);
}
/**
* iommu_vmap - (d)-(p)-(v) address mapper
* @obj: objective iommu
* @sgt: address of scatter gather table
* @flags: iovma and page property
*
* Creates 1-n-1 mapping with given @sgt and returns @da.
* All @sgt element must be io page size aligned.
*/
u32 iommu_vmap(struct iommu *obj, u32 da, const struct sg_table *sgt,
u32 flags)
{
size_t bytes;
void *va = NULL;
if (!obj || !obj->dev || !sgt)
return -EINVAL;
bytes = sgtable_len(sgt);
if (!bytes)
return -EINVAL;
bytes = PAGE_ALIGN(bytes);
if (flags & IOVMF_MMIO) {
va = vmap_sg(sgt);
if (IS_ERR(va))
return PTR_ERR(va);
}
flags &= IOVMF_HW_MASK;
flags |= IOVMF_DISCONT;
flags |= IOVMF_MMIO;
da = __iommu_vmap(obj, da, sgt, va, bytes, flags);
if (IS_ERR_VALUE(da))
vunmap_sg(va);
return da;
}
EXPORT_SYMBOL_GPL(iommu_vmap);
/**
* iommu_vunmap - release virtual mapping obtained by 'iommu_vmap()'
* @obj: objective iommu
* @da: iommu device virtual address
*
* Free the iommu virtually contiguous memory area starting at
* @da, which was returned by 'iommu_vmap()'.
*/
struct sg_table *iommu_vunmap(struct iommu *obj, u32 da)
{
struct sg_table *sgt;
/*
* 'sgt' is allocated before 'iommu_vmalloc()' is called.
* Just returns 'sgt' to the caller to free
*/
sgt = unmap_vm_area(obj, da, vunmap_sg, IOVMF_DISCONT | IOVMF_MMIO);
if (!sgt)
dev_dbg(obj->dev, "%s: No sgt\n", __func__);
return sgt;
}
EXPORT_SYMBOL_GPL(iommu_vunmap);
/**
* iommu_vmalloc - (d)-(p)-(v) address allocator and mapper
* @obj: objective iommu
* @da: contiguous iommu virtual memory
* @bytes: allocation size
* @flags: iovma and page property
*
* Allocate @bytes linearly and creates 1-n-1 mapping and returns
* @da again, which might be adjusted if 'IOVMF_DA_FIXED' is not set.
*/
u32 iommu_vmalloc(struct iommu *obj, u32 da, size_t bytes, u32 flags)
{
void *va;
struct sg_table *sgt;
if (!obj || !obj->dev || !bytes)
return -EINVAL;
bytes = PAGE_ALIGN(bytes);
va = vmalloc(bytes);
if (!va)
return -ENOMEM;
flags &= IOVMF_HW_MASK;
flags |= IOVMF_DISCONT;
flags |= IOVMF_ALLOC;
sgt = sgtable_alloc(bytes, flags, da, 0);
if (IS_ERR(sgt)) {
da = PTR_ERR(sgt);
goto err_sgt_alloc;
}
sgtable_fill_vmalloc(sgt, va);
da = __iommu_vmap(obj, da, sgt, va, bytes, flags);
if (IS_ERR_VALUE(da))
goto err_iommu_vmap;
return da;
err_iommu_vmap:
sgtable_drain_vmalloc(sgt);
sgtable_free(sgt);
err_sgt_alloc:
vfree(va);
return da;
}
EXPORT_SYMBOL_GPL(iommu_vmalloc);
/**
* iommu_vfree - release memory allocated by 'iommu_vmalloc()'
* @obj: objective iommu
* @da: iommu device virtual address
*
* Frees the iommu virtually continuous memory area starting at
* @da, as obtained from 'iommu_vmalloc()'.
*/
void iommu_vfree(struct iommu *obj, const u32 da)
{
struct sg_table *sgt;
sgt = unmap_vm_area(obj, da, vfree, IOVMF_DISCONT | IOVMF_ALLOC);
if (!sgt)
dev_dbg(obj->dev, "%s: No sgt\n", __func__);
sgtable_free(sgt);
}
EXPORT_SYMBOL_GPL(iommu_vfree);
static u32 __iommu_kmap(struct iommu *obj, u32 da, u32 pa, void *va,
size_t bytes, u32 flags)
{
struct sg_table *sgt;
sgt = sgtable_alloc(bytes, flags, da, pa);
if (IS_ERR(sgt))
return PTR_ERR(sgt);
sgtable_fill_kmalloc(sgt, pa, da, bytes);
da = map_iommu_region(obj, da, sgt, va, bytes, flags);
if (IS_ERR_VALUE(da)) {
sgtable_drain_kmalloc(sgt);
sgtable_free(sgt);
}
return da;
}
/**
* iommu_kmap - (d)-(p)-(v) address mapper
* @obj: objective iommu
* @da: contiguous iommu virtual memory
* @pa: contiguous physical memory
* @flags: iovma and page property
*
* Creates 1-1-1 mapping and returns @da again, which can be
* adjusted if 'IOVMF_DA_FIXED' is not set.
*/
u32 iommu_kmap(struct iommu *obj, u32 da, u32 pa, size_t bytes,
u32 flags)
{
void *va;
if (!obj || !obj->dev || !bytes)
return -EINVAL;
bytes = PAGE_ALIGN(bytes);
va = ioremap(pa, bytes);
if (!va)
return -ENOMEM;
flags &= IOVMF_HW_MASK;
flags |= IOVMF_LINEAR;
flags |= IOVMF_MMIO;
da = __iommu_kmap(obj, da, pa, va, bytes, flags);
if (IS_ERR_VALUE(da))
iounmap(va);
return da;
}
EXPORT_SYMBOL_GPL(iommu_kmap);
/**
* iommu_kunmap - release virtual mapping obtained by 'iommu_kmap()'
* @obj: objective iommu
* @da: iommu device virtual address
*
* Frees the iommu virtually contiguous memory area starting at
* @da, which was passed to and was returned by'iommu_kmap()'.
*/
void iommu_kunmap(struct iommu *obj, u32 da)
{
struct sg_table *sgt;
typedef void (*func_t)(const void *);
sgt = unmap_vm_area(obj, da, (func_t)iounmap,
IOVMF_LINEAR | IOVMF_MMIO);
if (!sgt)
dev_dbg(obj->dev, "%s: No sgt\n", __func__);
sgtable_free(sgt);
}
EXPORT_SYMBOL_GPL(iommu_kunmap);
/**
* iommu_kmalloc - (d)-(p)-(v) address allocator and mapper
* @obj: objective iommu
* @da: contiguous iommu virtual memory
* @bytes: bytes for allocation
* @flags: iovma and page property
*
* Allocate @bytes linearly and creates 1-1-1 mapping and returns
* @da again, which might be adjusted if 'IOVMF_DA_FIXED' is not set.
*/
u32 iommu_kmalloc(struct iommu *obj, u32 da, size_t bytes, u32 flags)
{
void *va;
u32 pa;
if (!obj || !obj->dev || !bytes)
return -EINVAL;
bytes = PAGE_ALIGN(bytes);
va = kmalloc(bytes, GFP_KERNEL | GFP_DMA);
if (!va)
return -ENOMEM;
pa = virt_to_phys(va);
flags &= IOVMF_HW_MASK;
flags |= IOVMF_LINEAR;
flags |= IOVMF_ALLOC;
da = __iommu_kmap(obj, da, pa, va, bytes, flags);
if (IS_ERR_VALUE(da))
kfree(va);
return da;
}
EXPORT_SYMBOL_GPL(iommu_kmalloc);
/**
* iommu_kfree - release virtual mapping obtained by 'iommu_kmalloc()'
* @obj: objective iommu
* @da: iommu device virtual address
*
* Frees the iommu virtually contiguous memory area starting at
* @da, which was passed to and was returned by'iommu_kmalloc()'.
*/
void iommu_kfree(struct iommu *obj, u32 da)
{
struct sg_table *sgt;
sgt = unmap_vm_area(obj, da, kfree, IOVMF_LINEAR | IOVMF_ALLOC);
if (!sgt)
dev_dbg(obj->dev, "%s: No sgt\n", __func__);
sgtable_free(sgt);
}
EXPORT_SYMBOL_GPL(iommu_kfree);
static int __init iovmm_init(void)
{
const unsigned long flags = SLAB_HWCACHE_ALIGN;
struct kmem_cache *p;
p = kmem_cache_create("iovm_area_cache", sizeof(struct iovm_struct), 0,
flags, NULL);
if (!p)
return -ENOMEM;
iovm_area_cachep = p;
return 0;
}
module_init(iovmm_init);
static void __exit iovmm_exit(void)
{
kmem_cache_destroy(iovm_area_cachep);
}
module_exit(iovmm_exit);
MODULE_DESCRIPTION("omap iommu: simple virtual address space management");
MODULE_AUTHOR("Hiroshi DOYU <Hiroshi.DOYU@nokia.com>");
MODULE_LICENSE("GPL v2");