mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 10:49:33 +00:00
![Wu, Bryan](/assets/img/avatar_default.png)
num_physpages is not exported out in mm/nommu.c, so the ip_conntrack module link will fail. Signed-off-by: Bryan Wu <bryan.wu@analog.com> Acked-By: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1377 lines
32 KiB
C
1377 lines
32 KiB
C
/*
|
|
* linux/mm/nommu.c
|
|
*
|
|
* Replacement code for mm functions to support CPU's that don't
|
|
* have any form of memory management unit (thus no virtual memory).
|
|
*
|
|
* See Documentation/nommu-mmap.txt
|
|
*
|
|
* Copyright (c) 2004-2005 David Howells <dhowells@redhat.com>
|
|
* Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
|
|
* Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
|
|
* Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/file.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/vmalloc.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/backing-dev.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/personality.h>
|
|
#include <linux/security.h>
|
|
#include <linux/syscalls.h>
|
|
|
|
#include <asm/uaccess.h>
|
|
#include <asm/tlb.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
void *high_memory;
|
|
struct page *mem_map;
|
|
unsigned long max_mapnr;
|
|
unsigned long num_physpages;
|
|
unsigned long askedalloc, realalloc;
|
|
atomic_t vm_committed_space = ATOMIC_INIT(0);
|
|
int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
|
|
int sysctl_overcommit_ratio = 50; /* default is 50% */
|
|
int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
|
|
int heap_stack_gap = 0;
|
|
|
|
EXPORT_SYMBOL(mem_map);
|
|
EXPORT_SYMBOL(__vm_enough_memory);
|
|
EXPORT_SYMBOL(num_physpages);
|
|
|
|
/* list of shareable VMAs */
|
|
struct rb_root nommu_vma_tree = RB_ROOT;
|
|
DECLARE_RWSEM(nommu_vma_sem);
|
|
|
|
struct vm_operations_struct generic_file_vm_ops = {
|
|
};
|
|
|
|
EXPORT_SYMBOL(vfree);
|
|
EXPORT_SYMBOL(vmalloc_to_page);
|
|
EXPORT_SYMBOL(vmalloc_32);
|
|
EXPORT_SYMBOL(vmap);
|
|
EXPORT_SYMBOL(vunmap);
|
|
|
|
/*
|
|
* Handle all mappings that got truncated by a "truncate()"
|
|
* system call.
|
|
*
|
|
* NOTE! We have to be ready to update the memory sharing
|
|
* between the file and the memory map for a potential last
|
|
* incomplete page. Ugly, but necessary.
|
|
*/
|
|
int vmtruncate(struct inode *inode, loff_t offset)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
unsigned long limit;
|
|
|
|
if (inode->i_size < offset)
|
|
goto do_expand;
|
|
i_size_write(inode, offset);
|
|
|
|
truncate_inode_pages(mapping, offset);
|
|
goto out_truncate;
|
|
|
|
do_expand:
|
|
limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
|
|
if (limit != RLIM_INFINITY && offset > limit)
|
|
goto out_sig;
|
|
if (offset > inode->i_sb->s_maxbytes)
|
|
goto out;
|
|
i_size_write(inode, offset);
|
|
|
|
out_truncate:
|
|
if (inode->i_op && inode->i_op->truncate)
|
|
inode->i_op->truncate(inode);
|
|
return 0;
|
|
out_sig:
|
|
send_sig(SIGXFSZ, current, 0);
|
|
out:
|
|
return -EFBIG;
|
|
}
|
|
|
|
EXPORT_SYMBOL(vmtruncate);
|
|
|
|
/*
|
|
* Return the total memory allocated for this pointer, not
|
|
* just what the caller asked for.
|
|
*
|
|
* Doesn't have to be accurate, i.e. may have races.
|
|
*/
|
|
unsigned int kobjsize(const void *objp)
|
|
{
|
|
struct page *page;
|
|
|
|
if (!objp || !((page = virt_to_page(objp))))
|
|
return 0;
|
|
|
|
if (PageSlab(page))
|
|
return ksize(objp);
|
|
|
|
BUG_ON(page->index < 0);
|
|
BUG_ON(page->index >= MAX_ORDER);
|
|
|
|
return (PAGE_SIZE << page->index);
|
|
}
|
|
|
|
/*
|
|
* get a list of pages in an address range belonging to the specified process
|
|
* and indicate the VMA that covers each page
|
|
* - this is potentially dodgy as we may end incrementing the page count of a
|
|
* slab page or a secondary page from a compound page
|
|
* - don't permit access to VMAs that don't support it, such as I/O mappings
|
|
*/
|
|
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
|
|
unsigned long start, int len, int write, int force,
|
|
struct page **pages, struct vm_area_struct **vmas)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
unsigned long vm_flags;
|
|
int i;
|
|
|
|
/* calculate required read or write permissions.
|
|
* - if 'force' is set, we only require the "MAY" flags.
|
|
*/
|
|
vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
|
|
vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
|
|
|
|
for (i = 0; i < len; i++) {
|
|
vma = find_vma(mm, start);
|
|
if (!vma)
|
|
goto finish_or_fault;
|
|
|
|
/* protect what we can, including chardevs */
|
|
if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
|
|
!(vm_flags & vma->vm_flags))
|
|
goto finish_or_fault;
|
|
|
|
if (pages) {
|
|
pages[i] = virt_to_page(start);
|
|
if (pages[i])
|
|
page_cache_get(pages[i]);
|
|
}
|
|
if (vmas)
|
|
vmas[i] = vma;
|
|
start += PAGE_SIZE;
|
|
}
|
|
|
|
return i;
|
|
|
|
finish_or_fault:
|
|
return i ? : -EFAULT;
|
|
}
|
|
|
|
EXPORT_SYMBOL(get_user_pages);
|
|
|
|
DEFINE_RWLOCK(vmlist_lock);
|
|
struct vm_struct *vmlist;
|
|
|
|
void vfree(void *addr)
|
|
{
|
|
kfree(addr);
|
|
}
|
|
|
|
void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
|
|
{
|
|
/*
|
|
* kmalloc doesn't like __GFP_HIGHMEM for some reason
|
|
*/
|
|
return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
|
|
}
|
|
|
|
struct page * vmalloc_to_page(void *addr)
|
|
{
|
|
return virt_to_page(addr);
|
|
}
|
|
|
|
unsigned long vmalloc_to_pfn(void *addr)
|
|
{
|
|
return page_to_pfn(virt_to_page(addr));
|
|
}
|
|
|
|
|
|
long vread(char *buf, char *addr, unsigned long count)
|
|
{
|
|
memcpy(buf, addr, count);
|
|
return count;
|
|
}
|
|
|
|
long vwrite(char *buf, char *addr, unsigned long count)
|
|
{
|
|
/* Don't allow overflow */
|
|
if ((unsigned long) addr + count < count)
|
|
count = -(unsigned long) addr;
|
|
|
|
memcpy(addr, buf, count);
|
|
return(count);
|
|
}
|
|
|
|
/*
|
|
* vmalloc - allocate virtually continguos memory
|
|
*
|
|
* @size: allocation size
|
|
*
|
|
* Allocate enough pages to cover @size from the page level
|
|
* allocator and map them into continguos 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);
|
|
|
|
void *vmalloc_node(unsigned long size, int node)
|
|
{
|
|
return vmalloc(size);
|
|
}
|
|
EXPORT_SYMBOL(vmalloc_node);
|
|
|
|
/*
|
|
* vmalloc_32 - allocate virtually continguos memory (32bit addressable)
|
|
*
|
|
* @size: allocation size
|
|
*
|
|
* Allocate enough 32bit PA addressable pages to cover @size from the
|
|
* page level allocator and map them into continguos kernel virtual space.
|
|
*/
|
|
void *vmalloc_32(unsigned long size)
|
|
{
|
|
return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
|
|
}
|
|
|
|
void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
|
|
{
|
|
BUG();
|
|
return NULL;
|
|
}
|
|
|
|
void vunmap(void *addr)
|
|
{
|
|
BUG();
|
|
}
|
|
|
|
/*
|
|
* sys_brk() for the most part doesn't need the global kernel
|
|
* lock, except when an application is doing something nasty
|
|
* like trying to un-brk an area that has already been mapped
|
|
* to a regular file. in this case, the unmapping will need
|
|
* to invoke file system routines that need the global lock.
|
|
*/
|
|
asmlinkage unsigned long sys_brk(unsigned long brk)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
if (brk < mm->start_brk || brk > mm->context.end_brk)
|
|
return mm->brk;
|
|
|
|
if (mm->brk == brk)
|
|
return mm->brk;
|
|
|
|
/*
|
|
* Always allow shrinking brk
|
|
*/
|
|
if (brk <= mm->brk) {
|
|
mm->brk = brk;
|
|
return brk;
|
|
}
|
|
|
|
/*
|
|
* Ok, looks good - let it rip.
|
|
*/
|
|
return mm->brk = brk;
|
|
}
|
|
|
|
#ifdef DEBUG
|
|
static void show_process_blocks(void)
|
|
{
|
|
struct vm_list_struct *vml;
|
|
|
|
printk("Process blocks %d:", current->pid);
|
|
|
|
for (vml = ¤t->mm->context.vmlist; vml; vml = vml->next) {
|
|
printk(" %p: %p", vml, vml->vma);
|
|
if (vml->vma)
|
|
printk(" (%d @%lx #%d)",
|
|
kobjsize((void *) vml->vma->vm_start),
|
|
vml->vma->vm_start,
|
|
atomic_read(&vml->vma->vm_usage));
|
|
printk(vml->next ? " ->" : ".\n");
|
|
}
|
|
}
|
|
#endif /* DEBUG */
|
|
|
|
/*
|
|
* add a VMA into a process's mm_struct in the appropriate place in the list
|
|
* - should be called with mm->mmap_sem held writelocked
|
|
*/
|
|
static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
|
|
{
|
|
struct vm_list_struct **ppv;
|
|
|
|
for (ppv = ¤t->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
|
|
if ((*ppv)->vma->vm_start > vml->vma->vm_start)
|
|
break;
|
|
|
|
vml->next = *ppv;
|
|
*ppv = vml;
|
|
}
|
|
|
|
/*
|
|
* look up the first VMA in which addr resides, NULL if none
|
|
* - should be called with mm->mmap_sem at least held readlocked
|
|
*/
|
|
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_list_struct *loop, *vml;
|
|
|
|
/* search the vm_start ordered list */
|
|
vml = NULL;
|
|
for (loop = mm->context.vmlist; loop; loop = loop->next) {
|
|
if (loop->vma->vm_start > addr)
|
|
break;
|
|
vml = loop;
|
|
}
|
|
|
|
if (vml && vml->vma->vm_end > addr)
|
|
return vml->vma;
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(find_vma);
|
|
|
|
/*
|
|
* find a VMA
|
|
* - we don't extend stack VMAs under NOMMU conditions
|
|
*/
|
|
struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
return find_vma(mm, addr);
|
|
}
|
|
|
|
/*
|
|
* look up the first VMA exactly that exactly matches addr
|
|
* - should be called with mm->mmap_sem at least held readlocked
|
|
*/
|
|
static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
|
|
unsigned long addr)
|
|
{
|
|
struct vm_list_struct *vml;
|
|
|
|
/* search the vm_start ordered list */
|
|
for (vml = mm->context.vmlist; vml; vml = vml->next) {
|
|
if (vml->vma->vm_start == addr)
|
|
return vml->vma;
|
|
if (vml->vma->vm_start > addr)
|
|
break;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find a VMA in the global tree
|
|
*/
|
|
static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct rb_node *n = nommu_vma_tree.rb_node;
|
|
|
|
while (n) {
|
|
vma = rb_entry(n, struct vm_area_struct, vm_rb);
|
|
|
|
if (start < vma->vm_start)
|
|
n = n->rb_left;
|
|
else if (start > vma->vm_start)
|
|
n = n->rb_right;
|
|
else
|
|
return vma;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* add a VMA in the global tree
|
|
*/
|
|
static void add_nommu_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct vm_area_struct *pvma;
|
|
struct address_space *mapping;
|
|
struct rb_node **p = &nommu_vma_tree.rb_node;
|
|
struct rb_node *parent = NULL;
|
|
|
|
/* add the VMA to the mapping */
|
|
if (vma->vm_file) {
|
|
mapping = vma->vm_file->f_mapping;
|
|
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma_prio_tree_insert(vma, &mapping->i_mmap);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
}
|
|
|
|
/* add the VMA to the master list */
|
|
while (*p) {
|
|
parent = *p;
|
|
pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
|
|
|
|
if (vma->vm_start < pvma->vm_start) {
|
|
p = &(*p)->rb_left;
|
|
}
|
|
else if (vma->vm_start > pvma->vm_start) {
|
|
p = &(*p)->rb_right;
|
|
}
|
|
else {
|
|
/* mappings are at the same address - this can only
|
|
* happen for shared-mem chardevs and shared file
|
|
* mappings backed by ramfs/tmpfs */
|
|
BUG_ON(!(pvma->vm_flags & VM_SHARED));
|
|
|
|
if (vma < pvma)
|
|
p = &(*p)->rb_left;
|
|
else if (vma > pvma)
|
|
p = &(*p)->rb_right;
|
|
else
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
rb_link_node(&vma->vm_rb, parent, p);
|
|
rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
|
|
}
|
|
|
|
/*
|
|
* delete a VMA from the global list
|
|
*/
|
|
static void delete_nommu_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct address_space *mapping;
|
|
|
|
/* remove the VMA from the mapping */
|
|
if (vma->vm_file) {
|
|
mapping = vma->vm_file->f_mapping;
|
|
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma_prio_tree_remove(vma, &mapping->i_mmap);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
}
|
|
|
|
/* remove from the master list */
|
|
rb_erase(&vma->vm_rb, &nommu_vma_tree);
|
|
}
|
|
|
|
/*
|
|
* determine whether a mapping should be permitted and, if so, what sort of
|
|
* mapping we're capable of supporting
|
|
*/
|
|
static int validate_mmap_request(struct file *file,
|
|
unsigned long addr,
|
|
unsigned long len,
|
|
unsigned long prot,
|
|
unsigned long flags,
|
|
unsigned long pgoff,
|
|
unsigned long *_capabilities)
|
|
{
|
|
unsigned long capabilities;
|
|
unsigned long reqprot = prot;
|
|
int ret;
|
|
|
|
/* do the simple checks first */
|
|
if (flags & MAP_FIXED || addr) {
|
|
printk(KERN_DEBUG
|
|
"%d: Can't do fixed-address/overlay mmap of RAM\n",
|
|
current->pid);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if ((flags & MAP_TYPE) != MAP_PRIVATE &&
|
|
(flags & MAP_TYPE) != MAP_SHARED)
|
|
return -EINVAL;
|
|
|
|
if (!len)
|
|
return -EINVAL;
|
|
|
|
/* Careful about overflows.. */
|
|
len = PAGE_ALIGN(len);
|
|
if (!len || len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
/* offset overflow? */
|
|
if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
|
|
return -EOVERFLOW;
|
|
|
|
if (file) {
|
|
/* validate file mapping requests */
|
|
struct address_space *mapping;
|
|
|
|
/* files must support mmap */
|
|
if (!file->f_op || !file->f_op->mmap)
|
|
return -ENODEV;
|
|
|
|
/* work out if what we've got could possibly be shared
|
|
* - we support chardevs that provide their own "memory"
|
|
* - we support files/blockdevs that are memory backed
|
|
*/
|
|
mapping = file->f_mapping;
|
|
if (!mapping)
|
|
mapping = file->f_path.dentry->d_inode->i_mapping;
|
|
|
|
capabilities = 0;
|
|
if (mapping && mapping->backing_dev_info)
|
|
capabilities = mapping->backing_dev_info->capabilities;
|
|
|
|
if (!capabilities) {
|
|
/* no explicit capabilities set, so assume some
|
|
* defaults */
|
|
switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
|
|
case S_IFREG:
|
|
case S_IFBLK:
|
|
capabilities = BDI_CAP_MAP_COPY;
|
|
break;
|
|
|
|
case S_IFCHR:
|
|
capabilities =
|
|
BDI_CAP_MAP_DIRECT |
|
|
BDI_CAP_READ_MAP |
|
|
BDI_CAP_WRITE_MAP;
|
|
break;
|
|
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* eliminate any capabilities that we can't support on this
|
|
* device */
|
|
if (!file->f_op->get_unmapped_area)
|
|
capabilities &= ~BDI_CAP_MAP_DIRECT;
|
|
if (!file->f_op->read)
|
|
capabilities &= ~BDI_CAP_MAP_COPY;
|
|
|
|
if (flags & MAP_SHARED) {
|
|
/* do checks for writing, appending and locking */
|
|
if ((prot & PROT_WRITE) &&
|
|
!(file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
if (IS_APPEND(file->f_path.dentry->d_inode) &&
|
|
(file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
if (locks_verify_locked(file->f_path.dentry->d_inode))
|
|
return -EAGAIN;
|
|
|
|
if (!(capabilities & BDI_CAP_MAP_DIRECT))
|
|
return -ENODEV;
|
|
|
|
if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
|
|
((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
|
|
((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
|
|
) {
|
|
printk("MAP_SHARED not completely supported on !MMU\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* we mustn't privatise shared mappings */
|
|
capabilities &= ~BDI_CAP_MAP_COPY;
|
|
}
|
|
else {
|
|
/* we're going to read the file into private memory we
|
|
* allocate */
|
|
if (!(capabilities & BDI_CAP_MAP_COPY))
|
|
return -ENODEV;
|
|
|
|
/* we don't permit a private writable mapping to be
|
|
* shared with the backing device */
|
|
if (prot & PROT_WRITE)
|
|
capabilities &= ~BDI_CAP_MAP_DIRECT;
|
|
}
|
|
|
|
/* handle executable mappings and implied executable
|
|
* mappings */
|
|
if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
|
|
if (prot & PROT_EXEC)
|
|
return -EPERM;
|
|
}
|
|
else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
|
|
/* handle implication of PROT_EXEC by PROT_READ */
|
|
if (current->personality & READ_IMPLIES_EXEC) {
|
|
if (capabilities & BDI_CAP_EXEC_MAP)
|
|
prot |= PROT_EXEC;
|
|
}
|
|
}
|
|
else if ((prot & PROT_READ) &&
|
|
(prot & PROT_EXEC) &&
|
|
!(capabilities & BDI_CAP_EXEC_MAP)
|
|
) {
|
|
/* backing file is not executable, try to copy */
|
|
capabilities &= ~BDI_CAP_MAP_DIRECT;
|
|
}
|
|
}
|
|
else {
|
|
/* anonymous mappings are always memory backed and can be
|
|
* privately mapped
|
|
*/
|
|
capabilities = BDI_CAP_MAP_COPY;
|
|
|
|
/* handle PROT_EXEC implication by PROT_READ */
|
|
if ((prot & PROT_READ) &&
|
|
(current->personality & READ_IMPLIES_EXEC))
|
|
prot |= PROT_EXEC;
|
|
}
|
|
|
|
/* allow the security API to have its say */
|
|
ret = security_file_mmap(file, reqprot, prot, flags);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
/* looks okay */
|
|
*_capabilities = capabilities;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* we've determined that we can make the mapping, now translate what we
|
|
* now know into VMA flags
|
|
*/
|
|
static unsigned long determine_vm_flags(struct file *file,
|
|
unsigned long prot,
|
|
unsigned long flags,
|
|
unsigned long capabilities)
|
|
{
|
|
unsigned long vm_flags;
|
|
|
|
vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
|
|
vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
|
|
/* vm_flags |= mm->def_flags; */
|
|
|
|
if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
|
|
/* attempt to share read-only copies of mapped file chunks */
|
|
if (file && !(prot & PROT_WRITE))
|
|
vm_flags |= VM_MAYSHARE;
|
|
}
|
|
else {
|
|
/* overlay a shareable mapping on the backing device or inode
|
|
* if possible - used for chardevs, ramfs/tmpfs/shmfs and
|
|
* romfs/cramfs */
|
|
if (flags & MAP_SHARED)
|
|
vm_flags |= VM_MAYSHARE | VM_SHARED;
|
|
else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
|
|
vm_flags |= VM_MAYSHARE;
|
|
}
|
|
|
|
/* refuse to let anyone share private mappings with this process if
|
|
* it's being traced - otherwise breakpoints set in it may interfere
|
|
* with another untraced process
|
|
*/
|
|
if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
|
|
vm_flags &= ~VM_MAYSHARE;
|
|
|
|
return vm_flags;
|
|
}
|
|
|
|
/*
|
|
* set up a shared mapping on a file
|
|
*/
|
|
static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
|
|
{
|
|
int ret;
|
|
|
|
ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
|
|
if (ret != -ENOSYS)
|
|
return ret;
|
|
|
|
/* getting an ENOSYS error indicates that direct mmap isn't
|
|
* possible (as opposed to tried but failed) so we'll fall
|
|
* through to making a private copy of the data and mapping
|
|
* that if we can */
|
|
return -ENODEV;
|
|
}
|
|
|
|
/*
|
|
* set up a private mapping or an anonymous shared mapping
|
|
*/
|
|
static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
|
|
{
|
|
void *base;
|
|
int ret;
|
|
|
|
/* invoke the file's mapping function so that it can keep track of
|
|
* shared mappings on devices or memory
|
|
* - VM_MAYSHARE will be set if it may attempt to share
|
|
*/
|
|
if (vma->vm_file) {
|
|
ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
|
|
if (ret != -ENOSYS) {
|
|
/* shouldn't return success if we're not sharing */
|
|
BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
|
|
return ret; /* success or a real error */
|
|
}
|
|
|
|
/* getting an ENOSYS error indicates that direct mmap isn't
|
|
* possible (as opposed to tried but failed) so we'll try to
|
|
* make a private copy of the data and map that instead */
|
|
}
|
|
|
|
/* allocate some memory to hold the mapping
|
|
* - note that this may not return a page-aligned address if the object
|
|
* we're allocating is smaller than a page
|
|
*/
|
|
base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
|
|
if (!base)
|
|
goto enomem;
|
|
|
|
vma->vm_start = (unsigned long) base;
|
|
vma->vm_end = vma->vm_start + len;
|
|
vma->vm_flags |= VM_MAPPED_COPY;
|
|
|
|
#ifdef WARN_ON_SLACK
|
|
if (len + WARN_ON_SLACK <= kobjsize(result))
|
|
printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
|
|
len, current->pid, kobjsize(result) - len);
|
|
#endif
|
|
|
|
if (vma->vm_file) {
|
|
/* read the contents of a file into the copy */
|
|
mm_segment_t old_fs;
|
|
loff_t fpos;
|
|
|
|
fpos = vma->vm_pgoff;
|
|
fpos <<= PAGE_SHIFT;
|
|
|
|
old_fs = get_fs();
|
|
set_fs(KERNEL_DS);
|
|
ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
|
|
set_fs(old_fs);
|
|
|
|
if (ret < 0)
|
|
goto error_free;
|
|
|
|
/* clear the last little bit */
|
|
if (ret < len)
|
|
memset(base + ret, 0, len - ret);
|
|
|
|
} else {
|
|
/* if it's an anonymous mapping, then just clear it */
|
|
memset(base, 0, len);
|
|
}
|
|
|
|
return 0;
|
|
|
|
error_free:
|
|
kfree(base);
|
|
vma->vm_start = 0;
|
|
return ret;
|
|
|
|
enomem:
|
|
printk("Allocation of length %lu from process %d failed\n",
|
|
len, current->pid);
|
|
show_free_areas();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* handle mapping creation for uClinux
|
|
*/
|
|
unsigned long do_mmap_pgoff(struct file *file,
|
|
unsigned long addr,
|
|
unsigned long len,
|
|
unsigned long prot,
|
|
unsigned long flags,
|
|
unsigned long pgoff)
|
|
{
|
|
struct vm_list_struct *vml = NULL;
|
|
struct vm_area_struct *vma = NULL;
|
|
struct rb_node *rb;
|
|
unsigned long capabilities, vm_flags;
|
|
void *result;
|
|
int ret;
|
|
|
|
/* decide whether we should attempt the mapping, and if so what sort of
|
|
* mapping */
|
|
ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
|
|
&capabilities);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
/* we've determined that we can make the mapping, now translate what we
|
|
* now know into VMA flags */
|
|
vm_flags = determine_vm_flags(file, prot, flags, capabilities);
|
|
|
|
/* we're going to need to record the mapping if it works */
|
|
vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
|
|
if (!vml)
|
|
goto error_getting_vml;
|
|
|
|
down_write(&nommu_vma_sem);
|
|
|
|
/* if we want to share, we need to check for VMAs created by other
|
|
* mmap() calls that overlap with our proposed mapping
|
|
* - we can only share with an exact match on most regular files
|
|
* - shared mappings on character devices and memory backed files are
|
|
* permitted to overlap inexactly as far as we are concerned for in
|
|
* these cases, sharing is handled in the driver or filesystem rather
|
|
* than here
|
|
*/
|
|
if (vm_flags & VM_MAYSHARE) {
|
|
unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
unsigned long vmpglen;
|
|
|
|
/* suppress VMA sharing for shared regions */
|
|
if (vm_flags & VM_SHARED &&
|
|
capabilities & BDI_CAP_MAP_DIRECT)
|
|
goto dont_share_VMAs;
|
|
|
|
for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
|
|
vma = rb_entry(rb, struct vm_area_struct, vm_rb);
|
|
|
|
if (!(vma->vm_flags & VM_MAYSHARE))
|
|
continue;
|
|
|
|
/* search for overlapping mappings on the same file */
|
|
if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
|
|
continue;
|
|
|
|
if (vma->vm_pgoff >= pgoff + pglen)
|
|
continue;
|
|
|
|
vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
|
|
vmpglen >>= PAGE_SHIFT;
|
|
if (pgoff >= vma->vm_pgoff + vmpglen)
|
|
continue;
|
|
|
|
/* handle inexactly overlapping matches between mappings */
|
|
if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
|
|
if (!(capabilities & BDI_CAP_MAP_DIRECT))
|
|
goto sharing_violation;
|
|
continue;
|
|
}
|
|
|
|
/* we've found a VMA we can share */
|
|
atomic_inc(&vma->vm_usage);
|
|
|
|
vml->vma = vma;
|
|
result = (void *) vma->vm_start;
|
|
goto shared;
|
|
}
|
|
|
|
dont_share_VMAs:
|
|
vma = NULL;
|
|
|
|
/* obtain the address at which to make a shared mapping
|
|
* - this is the hook for quasi-memory character devices to
|
|
* tell us the location of a shared mapping
|
|
*/
|
|
if (file && file->f_op->get_unmapped_area) {
|
|
addr = file->f_op->get_unmapped_area(file, addr, len,
|
|
pgoff, flags);
|
|
if (IS_ERR((void *) addr)) {
|
|
ret = addr;
|
|
if (ret != (unsigned long) -ENOSYS)
|
|
goto error;
|
|
|
|
/* the driver refused to tell us where to site
|
|
* the mapping so we'll have to attempt to copy
|
|
* it */
|
|
ret = (unsigned long) -ENODEV;
|
|
if (!(capabilities & BDI_CAP_MAP_COPY))
|
|
goto error;
|
|
|
|
capabilities &= ~BDI_CAP_MAP_DIRECT;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* we're going to need a VMA struct as well */
|
|
vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
|
|
if (!vma)
|
|
goto error_getting_vma;
|
|
|
|
INIT_LIST_HEAD(&vma->anon_vma_node);
|
|
atomic_set(&vma->vm_usage, 1);
|
|
if (file)
|
|
get_file(file);
|
|
vma->vm_file = file;
|
|
vma->vm_flags = vm_flags;
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
vma->vm_pgoff = pgoff;
|
|
|
|
vml->vma = vma;
|
|
|
|
/* set up the mapping */
|
|
if (file && vma->vm_flags & VM_SHARED)
|
|
ret = do_mmap_shared_file(vma, len);
|
|
else
|
|
ret = do_mmap_private(vma, len);
|
|
if (ret < 0)
|
|
goto error;
|
|
|
|
/* okay... we have a mapping; now we have to register it */
|
|
result = (void *) vma->vm_start;
|
|
|
|
if (vma->vm_flags & VM_MAPPED_COPY) {
|
|
realalloc += kobjsize(result);
|
|
askedalloc += len;
|
|
}
|
|
|
|
realalloc += kobjsize(vma);
|
|
askedalloc += sizeof(*vma);
|
|
|
|
current->mm->total_vm += len >> PAGE_SHIFT;
|
|
|
|
add_nommu_vma(vma);
|
|
|
|
shared:
|
|
realalloc += kobjsize(vml);
|
|
askedalloc += sizeof(*vml);
|
|
|
|
add_vma_to_mm(current->mm, vml);
|
|
|
|
up_write(&nommu_vma_sem);
|
|
|
|
if (prot & PROT_EXEC)
|
|
flush_icache_range((unsigned long) result,
|
|
(unsigned long) result + len);
|
|
|
|
#ifdef DEBUG
|
|
printk("do_mmap:\n");
|
|
show_process_blocks();
|
|
#endif
|
|
|
|
return (unsigned long) result;
|
|
|
|
error:
|
|
up_write(&nommu_vma_sem);
|
|
kfree(vml);
|
|
if (vma) {
|
|
if (vma->vm_file)
|
|
fput(vma->vm_file);
|
|
kfree(vma);
|
|
}
|
|
return ret;
|
|
|
|
sharing_violation:
|
|
up_write(&nommu_vma_sem);
|
|
printk("Attempt to share mismatched mappings\n");
|
|
kfree(vml);
|
|
return -EINVAL;
|
|
|
|
error_getting_vma:
|
|
up_write(&nommu_vma_sem);
|
|
kfree(vml);
|
|
printk("Allocation of vma for %lu byte allocation from process %d failed\n",
|
|
len, current->pid);
|
|
show_free_areas();
|
|
return -ENOMEM;
|
|
|
|
error_getting_vml:
|
|
printk("Allocation of vml for %lu byte allocation from process %d failed\n",
|
|
len, current->pid);
|
|
show_free_areas();
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* handle mapping disposal for uClinux
|
|
*/
|
|
static void put_vma(struct vm_area_struct *vma)
|
|
{
|
|
if (vma) {
|
|
down_write(&nommu_vma_sem);
|
|
|
|
if (atomic_dec_and_test(&vma->vm_usage)) {
|
|
delete_nommu_vma(vma);
|
|
|
|
if (vma->vm_ops && vma->vm_ops->close)
|
|
vma->vm_ops->close(vma);
|
|
|
|
/* IO memory and memory shared directly out of the pagecache from
|
|
* ramfs/tmpfs mustn't be released here */
|
|
if (vma->vm_flags & VM_MAPPED_COPY) {
|
|
realalloc -= kobjsize((void *) vma->vm_start);
|
|
askedalloc -= vma->vm_end - vma->vm_start;
|
|
kfree((void *) vma->vm_start);
|
|
}
|
|
|
|
realalloc -= kobjsize(vma);
|
|
askedalloc -= sizeof(*vma);
|
|
|
|
if (vma->vm_file)
|
|
fput(vma->vm_file);
|
|
kfree(vma);
|
|
}
|
|
|
|
up_write(&nommu_vma_sem);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* release a mapping
|
|
* - under NOMMU conditions the parameters must match exactly to the mapping to
|
|
* be removed
|
|
*/
|
|
int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
|
|
{
|
|
struct vm_list_struct *vml, **parent;
|
|
unsigned long end = addr + len;
|
|
|
|
#ifdef DEBUG
|
|
printk("do_munmap:\n");
|
|
#endif
|
|
|
|
for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
|
|
if ((*parent)->vma->vm_start > addr)
|
|
break;
|
|
if ((*parent)->vma->vm_start == addr &&
|
|
((len == 0) || ((*parent)->vma->vm_end == end)))
|
|
goto found;
|
|
}
|
|
|
|
printk("munmap of non-mmaped memory by process %d (%s): %p\n",
|
|
current->pid, current->comm, (void *) addr);
|
|
return -EINVAL;
|
|
|
|
found:
|
|
vml = *parent;
|
|
|
|
put_vma(vml->vma);
|
|
|
|
*parent = vml->next;
|
|
realalloc -= kobjsize(vml);
|
|
askedalloc -= sizeof(*vml);
|
|
kfree(vml);
|
|
|
|
update_hiwater_vm(mm);
|
|
mm->total_vm -= len >> PAGE_SHIFT;
|
|
|
|
#ifdef DEBUG
|
|
show_process_blocks();
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
asmlinkage long sys_munmap(unsigned long addr, size_t len)
|
|
{
|
|
int ret;
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
down_write(&mm->mmap_sem);
|
|
ret = do_munmap(mm, addr, len);
|
|
up_write(&mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Release all mappings
|
|
*/
|
|
void exit_mmap(struct mm_struct * mm)
|
|
{
|
|
struct vm_list_struct *tmp;
|
|
|
|
if (mm) {
|
|
#ifdef DEBUG
|
|
printk("Exit_mmap:\n");
|
|
#endif
|
|
|
|
mm->total_vm = 0;
|
|
|
|
while ((tmp = mm->context.vmlist)) {
|
|
mm->context.vmlist = tmp->next;
|
|
put_vma(tmp->vma);
|
|
|
|
realalloc -= kobjsize(tmp);
|
|
askedalloc -= sizeof(*tmp);
|
|
kfree(tmp);
|
|
}
|
|
|
|
#ifdef DEBUG
|
|
show_process_blocks();
|
|
#endif
|
|
}
|
|
}
|
|
|
|
unsigned long do_brk(unsigned long addr, unsigned long len)
|
|
{
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* expand (or shrink) an existing mapping, potentially moving it at the same
|
|
* time (controlled by the MREMAP_MAYMOVE flag and available VM space)
|
|
*
|
|
* under NOMMU conditions, we only permit changing a mapping's size, and only
|
|
* as long as it stays within the hole allocated by the kmalloc() call in
|
|
* do_mmap_pgoff() and the block is not shareable
|
|
*
|
|
* MREMAP_FIXED is not supported under NOMMU conditions
|
|
*/
|
|
unsigned long do_mremap(unsigned long addr,
|
|
unsigned long old_len, unsigned long new_len,
|
|
unsigned long flags, unsigned long new_addr)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
|
|
/* insanity checks first */
|
|
if (new_len == 0)
|
|
return (unsigned long) -EINVAL;
|
|
|
|
if (flags & MREMAP_FIXED && new_addr != addr)
|
|
return (unsigned long) -EINVAL;
|
|
|
|
vma = find_vma_exact(current->mm, addr);
|
|
if (!vma)
|
|
return (unsigned long) -EINVAL;
|
|
|
|
if (vma->vm_end != vma->vm_start + old_len)
|
|
return (unsigned long) -EFAULT;
|
|
|
|
if (vma->vm_flags & VM_MAYSHARE)
|
|
return (unsigned long) -EPERM;
|
|
|
|
if (new_len > kobjsize((void *) addr))
|
|
return (unsigned long) -ENOMEM;
|
|
|
|
/* all checks complete - do it */
|
|
vma->vm_end = vma->vm_start + new_len;
|
|
|
|
askedalloc -= old_len;
|
|
askedalloc += new_len;
|
|
|
|
return vma->vm_start;
|
|
}
|
|
|
|
asmlinkage unsigned long sys_mremap(unsigned long addr,
|
|
unsigned long old_len, unsigned long new_len,
|
|
unsigned long flags, unsigned long new_addr)
|
|
{
|
|
unsigned long ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
ret = do_mremap(addr, old_len, new_len, flags, new_addr);
|
|
up_write(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
|
|
unsigned int foll_flags)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
|
|
unsigned long to, unsigned long size, pgprot_t prot)
|
|
{
|
|
vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(remap_pfn_range);
|
|
|
|
void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
|
|
{
|
|
}
|
|
|
|
unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff, unsigned long flags)
|
|
{
|
|
return -ENOMEM;
|
|
}
|
|
|
|
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
}
|
|
|
|
void unmap_mapping_range(struct address_space *mapping,
|
|
loff_t const holebegin, loff_t const holelen,
|
|
int even_cows)
|
|
{
|
|
}
|
|
EXPORT_SYMBOL(unmap_mapping_range);
|
|
|
|
/*
|
|
* ask for an unmapped area at which to create a mapping on a file
|
|
*/
|
|
unsigned long get_unmapped_area(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
|
|
unsigned long, unsigned long);
|
|
|
|
get_area = current->mm->get_unmapped_area;
|
|
if (file && file->f_op && file->f_op->get_unmapped_area)
|
|
get_area = file->f_op->get_unmapped_area;
|
|
|
|
if (!get_area)
|
|
return -ENOSYS;
|
|
|
|
return get_area(file, addr, len, pgoff, flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL(get_unmapped_area);
|
|
|
|
/*
|
|
* Check that a process has enough memory to allocate a new virtual
|
|
* mapping. 0 means there is enough memory for the allocation to
|
|
* succeed and -ENOMEM implies there is not.
|
|
*
|
|
* We currently support three overcommit policies, which are set via the
|
|
* vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
|
|
*
|
|
* Strict overcommit modes added 2002 Feb 26 by Alan Cox.
|
|
* Additional code 2002 Jul 20 by Robert Love.
|
|
*
|
|
* cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
|
|
*
|
|
* Note this is a helper function intended to be used by LSMs which
|
|
* wish to use this logic.
|
|
*/
|
|
int __vm_enough_memory(long pages, int cap_sys_admin)
|
|
{
|
|
unsigned long free, allowed;
|
|
|
|
vm_acct_memory(pages);
|
|
|
|
/*
|
|
* Sometimes we want to use more memory than we have
|
|
*/
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
|
|
return 0;
|
|
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
|
|
unsigned long n;
|
|
|
|
free = global_page_state(NR_FILE_PAGES);
|
|
free += nr_swap_pages;
|
|
|
|
/*
|
|
* Any slabs which are created with the
|
|
* SLAB_RECLAIM_ACCOUNT flag claim to have contents
|
|
* which are reclaimable, under pressure. The dentry
|
|
* cache and most inode caches should fall into this
|
|
*/
|
|
free += global_page_state(NR_SLAB_RECLAIMABLE);
|
|
|
|
/*
|
|
* Leave the last 3% for root
|
|
*/
|
|
if (!cap_sys_admin)
|
|
free -= free / 32;
|
|
|
|
if (free > pages)
|
|
return 0;
|
|
|
|
/*
|
|
* nr_free_pages() is very expensive on large systems,
|
|
* only call if we're about to fail.
|
|
*/
|
|
n = nr_free_pages();
|
|
|
|
/*
|
|
* Leave reserved pages. The pages are not for anonymous pages.
|
|
*/
|
|
if (n <= totalreserve_pages)
|
|
goto error;
|
|
else
|
|
n -= totalreserve_pages;
|
|
|
|
/*
|
|
* Leave the last 3% for root
|
|
*/
|
|
if (!cap_sys_admin)
|
|
n -= n / 32;
|
|
free += n;
|
|
|
|
if (free > pages)
|
|
return 0;
|
|
|
|
goto error;
|
|
}
|
|
|
|
allowed = totalram_pages * sysctl_overcommit_ratio / 100;
|
|
/*
|
|
* Leave the last 3% for root
|
|
*/
|
|
if (!cap_sys_admin)
|
|
allowed -= allowed / 32;
|
|
allowed += total_swap_pages;
|
|
|
|
/* Don't let a single process grow too big:
|
|
leave 3% of the size of this process for other processes */
|
|
allowed -= current->mm->total_vm / 32;
|
|
|
|
/*
|
|
* cast `allowed' as a signed long because vm_committed_space
|
|
* sometimes has a negative value
|
|
*/
|
|
if (atomic_read(&vm_committed_space) < (long)allowed)
|
|
return 0;
|
|
error:
|
|
vm_unacct_memory(pages);
|
|
|
|
return -ENOMEM;
|
|
}
|
|
|
|
int in_gate_area_no_task(unsigned long addr)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
struct page *filemap_nopage(struct vm_area_struct *area,
|
|
unsigned long address, int *type)
|
|
{
|
|
BUG();
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Access another process' address space.
|
|
* - source/target buffer must be kernel space
|
|
*/
|
|
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct mm_struct *mm;
|
|
|
|
if (addr + len < addr)
|
|
return 0;
|
|
|
|
mm = get_task_mm(tsk);
|
|
if (!mm)
|
|
return 0;
|
|
|
|
down_read(&mm->mmap_sem);
|
|
|
|
/* the access must start within one of the target process's mappings */
|
|
vma = find_vma(mm, addr);
|
|
if (vma) {
|
|
/* don't overrun this mapping */
|
|
if (addr + len >= vma->vm_end)
|
|
len = vma->vm_end - addr;
|
|
|
|
/* only read or write mappings where it is permitted */
|
|
if (write && vma->vm_flags & VM_MAYWRITE)
|
|
len -= copy_to_user((void *) addr, buf, len);
|
|
else if (!write && vma->vm_flags & VM_MAYREAD)
|
|
len -= copy_from_user(buf, (void *) addr, len);
|
|
else
|
|
len = 0;
|
|
} else {
|
|
len = 0;
|
|
}
|
|
|
|
up_read(&mm->mmap_sem);
|
|
mmput(mm);
|
|
return len;
|
|
}
|