Linux-2.6.33.2/mm/nommu.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) 2004-2008 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>
* Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org>
*/
#include <linux/module.h>
#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/tracehook.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>
#include <asm/mmu_context.h>
#include "internal.h"
static inline __attribute__((format(printf, 1, 2)))
void no_printk(const char *fmt, ...)
{
}
#if 0
#define kenter(FMT, ...) \
printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) \
printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) \
printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
#else
#define kenter(FMT, ...) \
no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) \
no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) \
no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
#endif
void *high_memory;
struct page *mem_map;
unsigned long max_mapnr;
unsigned long num_physpages;
unsigned long highest_memmap_pfn;
struct percpu_counter vm_committed_as;
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 sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
int heap_stack_gap = 0;
atomic_long_t mmap_pages_allocated;
EXPORT_SYMBOL(mem_map);
EXPORT_SYMBOL(num_physpages);
/* list of mapped, potentially shareable regions */
static struct kmem_cache *vm_region_jar;
struct rb_root nommu_region_tree = RB_ROOT;
DECLARE_RWSEM(nommu_region_sem);
const struct vm_operations_struct generic_file_vm_ops = {
};
/*
* 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 the object we have should not have ksize performed on it,
* return size of 0
*/
if (!objp || !virt_addr_valid(objp))
return 0;
page = virt_to_head_page(objp);
/*
* If the allocator sets PageSlab, we know the pointer came from
* kmalloc().
*/
if (PageSlab(page))
return ksize(objp);
/*
* If it's not a compound page, see if we have a matching VMA
* region. This test is intentionally done in reverse order,
* so if there's no VMA, we still fall through and hand back
* PAGE_SIZE for 0-order pages.
*/
if (!PageCompound(page)) {
struct vm_area_struct *vma;
vma = find_vma(current->mm, (unsigned long)objp);
if (vma)
return vma->vm_end - vma->vm_start;
}
/*
* The ksize() function is only guaranteed to work for pointers
* returned by kmalloc(). So handle arbitrary pointers here.
*/
return PAGE_SIZE << compound_order(page);
}
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int nr_pages, unsigned int foll_flags,
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 FOLL_FORCE is set, we only require the "MAY" flags.
*/
vm_flags = (foll_flags & FOLL_WRITE) ?
(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
vm_flags &= (foll_flags & FOLL_FORCE) ?
(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
for (i = 0; i < nr_pages; 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;
}
/*
* 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 nr_pages, int write, int force,
struct page **pages, struct vm_area_struct **vmas)
{
int flags = 0;
if (write)
flags |= FOLL_WRITE;
if (force)
flags |= FOLL_FORCE;
return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
}
EXPORT_SYMBOL(get_user_pages);
/**
* follow_pfn - look up PFN at a user virtual address
* @vma: memory mapping
* @address: user virtual address
* @pfn: location to store found PFN
*
* Only IO mappings and raw PFN mappings are allowed.
*
* Returns zero and the pfn at @pfn on success, -ve otherwise.
*/
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
unsigned long *pfn)
{
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
return -EINVAL;
*pfn = address >> PAGE_SHIFT;
return 0;
}
EXPORT_SYMBOL(follow_pfn);
DEFINE_RWLOCK(vmlist_lock);
struct vm_struct *vmlist;
void vfree(const void *addr)
{
kfree(addr);
}
EXPORT_SYMBOL(vfree);
void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
{
/*
* You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
* returns only a logical address.
*/
return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
}
EXPORT_SYMBOL(__vmalloc);
void *vmalloc_user(unsigned long size)
{
void *ret;
ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
PAGE_KERNEL);
if (ret) {
struct vm_area_struct *vma;
down_write(¤t->mm->mmap_sem);
vma = find_vma(current->mm, (unsigned long)ret);
if (vma)
vma->vm_flags |= VM_USERMAP;
up_write(¤t->mm->mmap_sem);
}
return ret;
}
EXPORT_SYMBOL(vmalloc_user);
struct page *vmalloc_to_page(const void *addr)
{
return virt_to_page(addr);
}
EXPORT_SYMBOL(vmalloc_to_page);
unsigned long vmalloc_to_pfn(const void *addr)
{
return page_to_pfn(virt_to_page(addr));
}
EXPORT_SYMBOL(vmalloc_to_pfn);
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);
#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);
}
/**
* 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 continguos kernel virtual space.
*/
void *vmalloc_32(unsigned long size)
{
return __vmalloc(size, GFP_KERNEL, 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.
*
* VM_USERMAP is set on the corresponding VMA so that subsequent calls to
* remap_vmalloc_range() are permissible.
*/
void *vmalloc_32_user(unsigned long size)
{
/*
* We'll have to sort out the ZONE_DMA bits for 64-bit,
* but for now this can simply use vmalloc_user() directly.
*/
return vmalloc_user(size);
}
EXPORT_SYMBOL(vmalloc_32_user);
void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
{
BUG();
return NULL;
}
EXPORT_SYMBOL(vmap);
void vunmap(const void *addr)
{
BUG();
}
EXPORT_SYMBOL(vunmap);
void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
{
BUG();
return NULL;
}
EXPORT_SYMBOL(vm_map_ram);
void vm_unmap_ram(const void *mem, unsigned int count)
{
BUG();
}
EXPORT_SYMBOL(vm_unmap_ram);
void vm_unmap_aliases(void)
{
}
EXPORT_SYMBOL_GPL(vm_unmap_aliases);
/*
* Implement a stub for vmalloc_sync_all() if the architecture chose not to
* have one.
*/
void __attribute__((weak)) vmalloc_sync_all(void)
{
}
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
struct page *page)
{
return -EINVAL;
}
EXPORT_SYMBOL(vm_insert_page);
/*
* 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.
*/
SYSCALL_DEFINE1(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.
*/
flush_icache_range(mm->brk, brk);
return mm->brk = brk;
}
/*
* initialise the VMA and region record slabs
*/
void __init mmap_init(void)
{
int ret;
ret = percpu_counter_init(&vm_committed_as, 0);
VM_BUG_ON(ret);
vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
}
/*
* validate the region tree
* - the caller must hold the region lock
*/
#ifdef CONFIG_DEBUG_NOMMU_REGIONS
static noinline void validate_nommu_regions(void)
{
struct vm_region *region, *last;
struct rb_node *p, *lastp;
lastp = rb_first(&nommu_region_tree);
if (!lastp)
return;
last = rb_entry(lastp, struct vm_region, vm_rb);
BUG_ON(unlikely(last->vm_end <= last->vm_start));
BUG_ON(unlikely(last->vm_top < last->vm_end));
while ((p = rb_next(lastp))) {
region = rb_entry(p, struct vm_region, vm_rb);
last = rb_entry(lastp, struct vm_region, vm_rb);
BUG_ON(unlikely(region->vm_end <= region->vm_start));
BUG_ON(unlikely(region->vm_top < region->vm_end));
BUG_ON(unlikely(region->vm_start < last->vm_top));
lastp = p;
}
}
#else
static void validate_nommu_regions(void)
{
}
#endif
/*
* add a region into the global tree
*/
static void add_nommu_region(struct vm_region *region)
{
struct vm_region *pregion;
struct rb_node **p, *parent;
validate_nommu_regions();
parent = NULL;
p = &nommu_region_tree.rb_node;
while (*p) {
parent = *p;
pregion = rb_entry(parent, struct vm_region, vm_rb);
if (region->vm_start < pregion->vm_start)
p = &(*p)->rb_left;
else if (region->vm_start > pregion->vm_start)
p = &(*p)->rb_right;
else if (pregion == region)
return;
else
BUG();
}
rb_link_node(®ion->vm_rb, parent, p);
rb_insert_color(®ion->vm_rb, &nommu_region_tree);
validate_nommu_regions();
}
/*
* delete a region from the global tree
*/
static void delete_nommu_region(struct vm_region *region)
{
BUG_ON(!nommu_region_tree.rb_node);
validate_nommu_regions();
rb_erase(®ion->vm_rb, &nommu_region_tree);
validate_nommu_regions();
}
/*
* free a contiguous series of pages
*/
static void free_page_series(unsigned long from, unsigned long to)
{
for (; from < to; from += PAGE_SIZE) {
struct page *page = virt_to_page(from);
kdebug("- free %lx", from);
atomic_long_dec(&mmap_pages_allocated);
if (page_count(page) != 1)
kdebug("free page %p: refcount not one: %d",
page, page_count(page));
put_page(page);
}
}
/*
* release a reference to a region
* - the caller must hold the region semaphore for writing, which this releases
* - the region may not have been added to the tree yet, in which case vm_top
* will equal vm_start
*/
static void __put_nommu_region(struct vm_region *region)
__releases(nommu_region_sem)
{
kenter("%p{%d}", region, region->vm_usage);
BUG_ON(!nommu_region_tree.rb_node);
if (--region->vm_usage == 0) {
if (region->vm_top > region->vm_start)
delete_nommu_region(region);
up_write(&nommu_region_sem);
if (region->vm_file)
fput(region->vm_file);
/* IO memory and memory shared directly out of the pagecache
* from ramfs/tmpfs mustn't be released here */
if (region->vm_flags & VM_MAPPED_COPY) {
kdebug("free series");
free_page_series(region->vm_start, region->vm_top);
}
kmem_cache_free(vm_region_jar, region);
} else {
up_write(&nommu_region_sem);
}
}
/*
* release a reference to a region
*/
static void put_nommu_region(struct vm_region *region)
{
down_write(&nommu_region_sem);
__put_nommu_region(region);
}
/*
* update protection on a vma
*/
static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
{
#ifdef CONFIG_MPU
struct mm_struct *mm = vma->vm_mm;
long start = vma->vm_start & PAGE_MASK;
while (start < vma->vm_end) {
protect_page(mm, start, flags);
start += PAGE_SIZE;
}
update_protections(mm);
#endif
}
/*
* add a VMA into a process's mm_struct in the appropriate place in the list
* and tree and add to the address space's page tree also if not an anonymous
* page
* - should be called with mm->mmap_sem held writelocked
*/
static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
{
struct vm_area_struct *pvma, **pp;
struct address_space *mapping;
struct rb_node **p, *parent;
kenter(",%p", vma);
BUG_ON(!vma->vm_region);
mm->map_count++;
vma->vm_mm = mm;
protect_vma(vma, vma->vm_flags);
/* 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 tree */
parent = NULL;
p = &mm->mm_rb.rb_node;
while (*p) {
parent = *p;
pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
/* sort by: start addr, end addr, VMA struct addr in that order
* (the latter is necessary as we may get identical VMAs) */
if (vma->vm_start < pvma->vm_start)
p = &(*p)->rb_left;
else if (vma->vm_start > pvma->vm_start)
p = &(*p)->rb_right;
else if (vma->vm_end < pvma->vm_end)
p = &(*p)->rb_left;
else if (vma->vm_end > pvma->vm_end)
p = &(*p)->rb_right;
else 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, &mm->mm_rb);
/* add VMA to the VMA list also */
for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
if (pvma->vm_start > vma->vm_start)
break;
if (pvma->vm_start < vma->vm_start)
continue;
if (pvma->vm_end < vma->vm_end)
break;
}
vma->vm_next = *pp;
*pp = vma;
}
/*
* delete a VMA from its owning mm_struct and address space
*/
static void delete_vma_from_mm(struct vm_area_struct *vma)
{
struct vm_area_struct **pp;
struct address_space *mapping;
struct mm_struct *mm = vma->vm_mm;
kenter("%p", vma);
protect_vma(vma, 0);
mm->map_count--;
if (mm->mmap_cache == vma)
mm->mmap_cache = NULL;
/* 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 MM's tree and list */
rb_erase(&vma->vm_rb, &mm->mm_rb);
for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
if (*pp == vma) {
*pp = vma->vm_next;
break;
}
}
vma->vm_mm = NULL;
}
/*
* destroy a VMA record
*/
static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
{
kenter("%p", vma);
if (vma->vm_ops && vma->vm_ops->close)
vma->vm_ops->close(vma);
if (vma->vm_file) {
fput(vma->vm_file);
if (vma->vm_flags & VM_EXECUTABLE)
removed_exe_file_vma(mm);
}
put_nommu_region(vma->vm_region);
kmem_cache_free(vm_area_cachep, vma);
}
/*
* 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_area_struct *vma;
struct rb_node *n = mm->mm_rb.rb_node;
/* check the cache first */
vma = mm->mmap_cache;
if (vma && vma->vm_start <= addr && vma->vm_end > addr)
return vma;
/* trawl the tree (there may be multiple mappings in which addr
* resides) */
for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
vma = rb_entry(n, struct vm_area_struct, vm_rb);
if (vma->vm_start > addr)
return NULL;
if (vma->vm_end > addr) {
mm->mmap_cache = vma;
return 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);
}
/*
* expand a stack to a given address
* - not supported under NOMMU conditions
*/
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
return -ENOMEM;
}
/*
* look up the first VMA exactly that exactly matches addr
* - should be called with mm->mmap_sem at least held readlocked
*/
static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
unsigned long addr,
unsigned long len)
{
struct vm_area_struct *vma;
struct rb_node *n = mm->mm_rb.rb_node;
unsigned long end = addr + len;
/* check the cache first */
vma = mm->mmap_cache;
if (vma && vma->vm_start == addr && vma->vm_end == end)
return vma;
/* trawl the tree (there may be multiple mappings in which addr
* resides) */
for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
vma = rb_entry(n, struct vm_area_struct, vm_rb);
if (vma->vm_start < addr)
continue;
if (vma->vm_start > addr)
return NULL;
if (vma->vm_end == end) {
mm->mmap_cache = vma;
return vma;
}
}
return NULL;
}
/*
* 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, rlen;
unsigned long reqprot = prot;
int ret;
/* do the simple checks first */
if (flags & MAP_FIXED) {
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.. */
rlen = PAGE_ALIGN(len);
if (!rlen || rlen > TASK_SIZE)
return -ENOMEM;
/* offset overflow? */
if ((pgoff + (rlen >> 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;
/* The file shall have been opened with read permission. */
if (!(file->f_mode & FMODE_READ))
return -EACCES;
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, addr, 0);
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) && tracehook_expect_breakpoints(current))
vm_flags &= ~VM_MAYSHARE;
return vm_flags;
}
/*
* set up a shared mapping on a file (the driver or filesystem provides and
* pins the storage)
*/
static int do_mmap_shared_file(struct vm_area_struct *vma)
{
int ret;
ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
if (ret == 0) {
vma->vm_region->vm_top = vma->vm_region->vm_end;
return 0;
}
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,
struct vm_region *region,
unsigned long len,
unsigned long capabilities)
{
struct page *pages;
unsigned long total, point, n, rlen;
void *base;
int ret, order;
/* 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 (capabilities & BDI_CAP_MAP_DIRECT) {
ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
if (ret == 0) {
/* shouldn't return success if we're not sharing */
BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
vma->vm_region->vm_top = vma->vm_region->vm_end;
return 0;
}
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 try to
* make a private copy of the data and map that instead */
}
rlen = PAGE_ALIGN(len);
/* 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
*/
order = get_order(rlen);
kdebug("alloc order %d for %lx", order, len);
pages = alloc_pages(GFP_KERNEL, order);
if (!pages)
goto enomem;
total = 1 << order;
atomic_long_add(total, &mmap_pages_allocated);
point = rlen >> PAGE_SHIFT;
/* we allocated a power-of-2 sized page set, so we may want to trim off
* the excess */
if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
while (total > point) {
order = ilog2(total - point);
n = 1 << order;
kdebug("shave %lu/%lu @%lu", n, total - point, total);
atomic_long_sub(n, &mmap_pages_allocated);
total -= n;
set_page_refcounted(pages + total);
__free_pages(pages + total, order);
}
}
for (point = 1; point < total; point++)
set_page_refcounted(&pages[point]);
base = page_address(pages);
region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
region->vm_start = (unsigned long) base;
region->vm_end = region->vm_start + rlen;
region->vm_top = region->vm_start + (total << PAGE_SHIFT);
vma->vm_start = region->vm_start;
vma->vm_end = region->vm_start + len;
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, rlen, &fpos);
set_fs(old_fs);
if (ret < 0)
goto error_free;
/* clear the last little bit */
if (ret < rlen)
memset(base + ret, 0, rlen - ret);
}
return 0;
error_free:
free_page_series(region->vm_start, region->vm_end);
region->vm_start = vma->vm_start = 0;
region->vm_end = vma->vm_end = 0;
region->vm_top = 0;
return ret;
enomem:
printk("Allocation of length %lu from process %d (%s) failed\n",
len, current->pid, current->comm);
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_area_struct *vma;
struct vm_region *region;
struct rb_node *rb;
unsigned long capabilities, vm_flags, result;
int ret;
kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
/* 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) {
kleave(" = %d [val]", ret);
return ret;
}
/* we ignore the address hint */
addr = 0;
/* 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 */
region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
if (!region)
goto error_getting_region;
vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
if (!vma)
goto error_getting_vma;
region->vm_usage = 1;
region->vm_flags = vm_flags;
region->vm_pgoff = pgoff;
INIT_LIST_HEAD(&vma->anon_vma_node);
vma->vm_flags = vm_flags;
vma->vm_pgoff = pgoff;
if (file) {
region->vm_file = file;
get_file(file);
vma->vm_file = file;
get_file(file);
if (vm_flags & VM_EXECUTABLE) {
added_exe_file_vma(current->mm);
vma->vm_mm = current->mm;
}
}
down_write(&nommu_region_sem);
/* if we want to share, we need to check for regions created by other
* mmap() calls that overlap with our proposed mapping
* - we can only share with a superset 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) {
struct vm_region *pregion;
unsigned long pglen, rpglen, pgend, rpgend, start;
pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
pgend = pgoff + pglen;
for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
pregion = rb_entry(rb, struct vm_region, vm_rb);
if (!(pregion->vm_flags & VM_MAYSHARE))
continue;
/* search for overlapping mappings on the same file */
if (pregion->vm_file->f_path.dentry->d_inode !=
file->f_path.dentry->d_inode)
continue;
if (pregion->vm_pgoff >= pgend)
continue;
rpglen = pregion->vm_end - pregion->vm_start;
rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
rpgend = pregion->vm_pgoff + rpglen;
if (pgoff >= rpgend)
continue;
/* handle inexactly overlapping matches between
* mappings */
if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
!(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
/* new mapping is not a subset of the region */
if (!(capabilities & BDI_CAP_MAP_DIRECT))
goto sharing_violation;
continue;
}
/* we've found a region we can share */
pregion->vm_usage++;
vma->vm_region = pregion;
start = pregion->vm_start;
start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
vma->vm_start = start;
vma->vm_end = start + len;
if (pregion->vm_flags & VM_MAPPED_COPY) {
kdebug("share copy");
vma->vm_flags |= VM_MAPPED_COPY;
} else {
kdebug("share mmap");
ret = do_mmap_shared_file(vma);
if (ret < 0) {
vma->vm_region = NULL;
vma->vm_start = 0;
vma->vm_end = 0;
pregion->vm_usage--;
pregion = NULL;
goto error_just_free;
}
}
fput(region->vm_file);
kmem_cache_free(vm_region_jar, region);
region = pregion;
result = start;
goto share;
}
/* 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 (capabilities & BDI_CAP_MAP_DIRECT) {
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_just_free;
/* 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_just_free;
capabilities &= ~BDI_CAP_MAP_DIRECT;
} else {
vma->vm_start = region->vm_start = addr;
vma->vm_end = region->vm_end = addr + len;
}
}
}
vma->vm_region = region;
/* set up the mapping
* - the region is filled in if BDI_CAP_MAP_DIRECT is still set
*/
if (file && vma->vm_flags & VM_SHARED)
ret = do_mmap_shared_file(vma);
else
ret = do_mmap_private(vma, region, len, capabilities);
if (ret < 0)
goto error_just_free;
add_nommu_region(region);
/* clear anonymous mappings that don't ask for uninitialized data */
if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
memset((void *)region->vm_start, 0,
region->vm_end - region->vm_start);
/* okay... we have a mapping; now we have to register it */
result = vma->vm_start;
current->mm->total_vm += len >> PAGE_SHIFT;
share:
add_vma_to_mm(current->mm, vma);
/* we flush the region from the icache only when the first executable
* mapping of it is made */
if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
flush_icache_range(region->vm_start, region->vm_end);
region->vm_icache_flushed = true;
}
up_write(&nommu_region_sem);
kleave(" = %lx", result);
return result;
error_just_free:
up_write(&nommu_region_sem);
error:
if (region->vm_file)
fput(region->vm_file);
kmem_cache_free(vm_region_jar, region);
if (vma->vm_file)
fput(vma->vm_file);
if (vma->vm_flags & VM_EXECUTABLE)
removed_exe_file_vma(vma->vm_mm);
kmem_cache_free(vm_area_cachep, vma);
kleave(" = %d", ret);
return ret;
sharing_violation:
up_write(&nommu_region_sem);
printk(KERN_WARNING "Attempt to share mismatched mappings\n");
ret = -EINVAL;
goto error;
error_getting_vma:
kmem_cache_free(vm_region_jar, region);
printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
" from process %d failed\n",
len, current->pid);
show_free_areas();
return -ENOMEM;
error_getting_region:
printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
" from process %d failed\n",
len, current->pid);
show_free_areas();
return -ENOMEM;
}
EXPORT_SYMBOL(do_mmap_pgoff);
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
unsigned long, prot, unsigned long, flags,
unsigned long, fd, unsigned long, pgoff)
{
struct file *file = NULL;
unsigned long retval = -EBADF;
if (!(flags & MAP_ANONYMOUS)) {
file = fget(fd);
if (!file)
goto out;
}
flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
down_write(¤t->mm->mmap_sem);
retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
up_write(¤t->mm->mmap_sem);
if (file)
fput(file);
out:
return retval;
}
/*
* split a vma into two pieces at address 'addr', a new vma is allocated either
* for the first part or the tail.
*/
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, int new_below)
{
struct vm_area_struct *new;
struct vm_region *region;
unsigned long npages;
kenter("");
/* we're only permitted to split anonymous regions (these should have
* only a single usage on the region) */
if (vma->vm_file)
return -ENOMEM;
if (mm->map_count >= sysctl_max_map_count)
return -ENOMEM;
region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
if (!region)
return -ENOMEM;
new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!new) {
kmem_cache_free(vm_region_jar, region);
return -ENOMEM;
}
/* most fields are the same, copy all, and then fixup */
*new = *vma;
*region = *vma->vm_region;
new->vm_region = region;
npages = (addr - vma->vm_start) >> PAGE_SHIFT;
if (new_below) {
region->vm_top = region->vm_end = new->vm_end = addr;
} else {
region->vm_start = new->vm_start = addr;
region->vm_pgoff = new->vm_pgoff += npages;
}
if (new->vm_ops && new->vm_ops->open)
new->vm_ops->open(new);
delete_vma_from_mm(vma);
down_write(&nommu_region_sem);
delete_nommu_region(vma->vm_region);
if (new_below) {
vma->vm_region->vm_start = vma->vm_start = addr;
vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
} else {
vma->vm_region->vm_end = vma->vm_end = addr;
vma->vm_region->vm_top = addr;
}
add_nommu_region(vma->vm_region);
add_nommu_region(new->vm_region);
up_write(&nommu_region_sem);
add_vma_to_mm(mm, vma);
add_vma_to_mm(mm, new);
return 0;
}
/*
* shrink a VMA by removing the specified chunk from either the beginning or
* the end
*/
static int shrink_vma(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long from, unsigned long to)
{
struct vm_region *region;
kenter("");
/* adjust the VMA's pointers, which may reposition it in the MM's tree
* and list */
delete_vma_from_mm(vma);
if (from > vma->vm_start)
vma->vm_end = from;
else
vma->vm_start = to;
add_vma_to_mm(mm, vma);
/* cut the backing region down to size */
region = vma->vm_region;
BUG_ON(region->vm_usage != 1);
down_write(&nommu_region_sem);
delete_nommu_region(region);
if (from > region->vm_start) {
to = region->vm_top;
region->vm_top = region->vm_end = from;
} else {
region->vm_start = to;
}
add_nommu_region(region);
up_write(&nommu_region_sem);
free_page_series(from, to);
return 0;
}
/*
* release a mapping
* - under NOMMU conditions the chunk to be unmapped must be backed by a single
* VMA, though it need not cover the whole VMA
*/
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
struct vm_area_struct *vma;
struct rb_node *rb;
unsigned long end = start + len;
int ret;
kenter(",%lx,%zx", start, len);
if (len == 0)
return -EINVAL;
/* find the first potentially overlapping VMA */
vma = find_vma(mm, start);
if (!vma) {
static int limit = 0;
if (limit < 5) {
printk(KERN_WARNING
"munmap of memory not mmapped by process %d"
" (%s): 0x%lx-0x%lx\n",
current->pid, current->comm,
start, start + len - 1);
limit++;
}
return -EINVAL;
}
/* we're allowed to split an anonymous VMA but not a file-backed one */
if (vma->vm_file) {
do {
if (start > vma->vm_start) {
kleave(" = -EINVAL [miss]");
return -EINVAL;
}
if (end == vma->vm_end)
goto erase_whole_vma;
rb = rb_next(&vma->vm_rb);
vma = rb_entry(rb, struct vm_area_struct, vm_rb);
} while (rb);
kleave(" = -EINVAL [split file]");
return -EINVAL;
} else {
/* the chunk must be a subset of the VMA found */
if (start == vma->vm_start && end == vma->vm_end)
goto erase_whole_vma;
if (start < vma->vm_start || end > vma->vm_end) {
kleave(" = -EINVAL [superset]");
return -EINVAL;
}
if (start & ~PAGE_MASK) {
kleave(" = -EINVAL [unaligned start]");
return -EINVAL;
}
if (end != vma->vm_end && end & ~PAGE_MASK) {
kleave(" = -EINVAL [unaligned split]");
return -EINVAL;
}
if (start != vma->vm_start && end != vma->vm_end) {
ret = split_vma(mm, vma, start, 1);
if (ret < 0) {
kleave(" = %d [split]", ret);
return ret;
}
}
return shrink_vma(mm, vma, start, end);
}
erase_whole_vma:
delete_vma_from_mm(vma);
delete_vma(mm, vma);
kleave(" = 0");
return 0;
}
EXPORT_SYMBOL(do_munmap);
SYSCALL_DEFINE2(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 the mappings made in a process's VM space
*/
void exit_mmap(struct mm_struct *mm)
{
struct vm_area_struct *vma;
if (!mm)
return;
kenter("");
mm->total_vm = 0;
while ((vma = mm->mmap)) {
mm->mmap = vma->vm_next;
delete_vma_from_mm(vma);
delete_vma(mm, vma);
}
kleave("");
}
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 region allocated by do_mmap_private() 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 (old_len == 0 || new_len == 0)
return (unsigned long) -EINVAL;
if (addr & ~PAGE_MASK)
return -EINVAL;
if (flags & MREMAP_FIXED && new_addr != addr)
return (unsigned long) -EINVAL;
vma = find_vma_exact(current->mm, addr, old_len);
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 > vma->vm_region->vm_end - vma->vm_region->vm_start)
return (unsigned long) -ENOMEM;
/* all checks complete - do it */
vma->vm_end = vma->vm_start + new_len;
return vma->vm_start;
}
EXPORT_SYMBOL(do_mremap);
SYSCALL_DEFINE5(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);
int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
unsigned long pgoff)
{
unsigned int size = vma->vm_end - vma->vm_start;
if (!(vma->vm_flags & VM_USERMAP))
return -EINVAL;
vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
vma->vm_end = vma->vm_start + size;
return 0;
}
EXPORT_SYMBOL(remap_vmalloc_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);
/*
* 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(struct mm_struct *mm, 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 */
if (mm)
allowed -= mm->total_vm / 32;
if (percpu_counter_read_positive(&vm_committed_as) < allowed)
return 0;
error:
vm_unacct_memory(pages);
return -ENOMEM;
}
int in_gate_area_no_task(unsigned long addr)
{
return 0;
}
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
BUG();
return 0;
}
EXPORT_SYMBOL(filemap_fault);
/*
* 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)
copy_to_user_page(vma, NULL, addr,
(void *) addr, buf, len);
else if (!write && vma->vm_flags & VM_MAYREAD)
copy_from_user_page(vma, NULL, addr,
buf, (void *) addr, len);
else
len = 0;
} else {
len = 0;
}
up_read(&mm->mmap_sem);
mmput(mm);
return len;
}
/**
* nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
* @inode: The inode to check
* @size: The current filesize of the inode
* @newsize: The proposed filesize of the inode
*
* Check the shared mappings on an inode on behalf of a shrinking truncate to
* make sure that that any outstanding VMAs aren't broken and then shrink the
* vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
* automatically grant mappings that are too large.
*/
int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
size_t newsize)
{
struct vm_area_struct *vma;
struct prio_tree_iter iter;
struct vm_region *region;
pgoff_t low, high;
size_t r_size, r_top;
low = newsize >> PAGE_SHIFT;
high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
down_write(&nommu_region_sem);
/* search for VMAs that fall within the dead zone */
vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
low, high) {
/* found one - only interested if it's shared out of the page
* cache */
if (vma->vm_flags & VM_SHARED) {
up_write(&nommu_region_sem);
return -ETXTBSY; /* not quite true, but near enough */
}
}
/* reduce any regions that overlap the dead zone - if in existence,
* these will be pointed to by VMAs that don't overlap the dead zone
*
* we don't check for any regions that start beyond the EOF as there
* shouldn't be any
*/
vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
0, ULONG_MAX) {
if (!(vma->vm_flags & VM_SHARED))
continue;
region = vma->vm_region;
r_size = region->vm_top - region->vm_start;
r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
if (r_top > newsize) {
region->vm_top -= r_top - newsize;
if (region->vm_end > region->vm_top)
region->vm_end = region->vm_top;
}
}
up_write(&nommu_region_sem);
return 0;
}