/*
* mm/mmap.c
*
* Written by obz.
*
* Address space accounting code <alan@redhat.com>
*/
#include <linux/slab.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/hugetlb.h>
#include <linux/profile.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
/*
* WARNING: the debugging will use recursive algorithms so never enable this
* unless you know what you are doing.
*/
#undef DEBUG_MM_RB
/* description of effects of mapping type and prot in current implementation.
* this is due to the limited x86 page protection hardware. The expected
* behavior is in parens:
*
* map_type prot
* PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
* MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
* w: (no) no w: (no) no w: (yes) yes w: (no) no
* x: (no) no x: (no) yes x: (no) yes x: (yes) yes
*
* MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
* w: (no) no w: (no) no w: (copy) copy w: (no) no
* x: (no) no x: (no) yes x: (no) yes x: (yes) yes
*
*/
pgprot_t protection_map[16] = {
__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
};
int sysctl_overcommit_memory = 0; /* default is heuristic overcommit */
int sysctl_overcommit_ratio = 50; /* default is 50% */
atomic_t vm_committed_space = ATOMIC_INIT(0);
EXPORT_SYMBOL(sysctl_overcommit_memory);
EXPORT_SYMBOL(sysctl_overcommit_ratio);
EXPORT_SYMBOL(vm_committed_space);
/*
* Requires inode->i_mapping->i_shared_sem
*/
static inline void
__remove_shared_vm_struct(struct vm_area_struct *vma, struct inode *inode)
{
if (inode) {
if (vma->vm_flags & VM_DENYWRITE)
atomic_inc(&inode->i_writecount);
list_del_init(&vma->shared);
}
}
/*
* Remove one vm structure from the inode's i_mapping address space.
*/
static void remove_shared_vm_struct(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
if (file) {
struct address_space *mapping = file->f_mapping;
down(&mapping->i_shared_sem);
__remove_shared_vm_struct(vma, file->f_dentry->d_inode);
up(&mapping->i_shared_sem);
}
}
/*
* 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)
{
unsigned long rlim, retval;
unsigned long newbrk, oldbrk;
struct mm_struct *mm = current->mm;
down_write(&mm->mmap_sem);
if (brk < mm->end_code)
goto out;
newbrk = PAGE_ALIGN(brk);
oldbrk = PAGE_ALIGN(mm->brk);
if (oldbrk == newbrk)
goto set_brk;
/* Always allow shrinking brk. */
if (brk <= mm->brk) {
if (!do_munmap(mm, newbrk, oldbrk-newbrk))
goto set_brk;
goto out;
}
/* Check against rlimit.. */
rlim = current->rlim[RLIMIT_DATA].rlim_cur;
if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
goto out;
/* Check against existing mmap mappings. */
if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
goto out;
/* Ok, looks good - let it rip. */
if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
goto out;
set_brk:
mm->brk = brk;
out:
retval = mm->brk;
up_write(&mm->mmap_sem);
return retval;
}
#ifdef DEBUG_MM_RB
static int browse_rb(struct rb_node * rb_node) {
int i = 0;
if (rb_node) {
i++;
i += browse_rb(rb_node->rb_left);
i += browse_rb(rb_node->rb_right);
}
return i;
}
static void validate_mm(struct mm_struct * mm) {
int bug = 0;
int i = 0;
struct vm_area_struct * tmp = mm->mmap;
while (tmp) {
tmp = tmp->vm_next;
i++;
}
if (i != mm->map_count)
printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
i = browse_rb(mm->mm_rb.rb_node);
if (i != mm->map_count)
printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
if (bug)
BUG();
}
#else
#define validate_mm(mm) do { } while (0)
#endif
static struct vm_area_struct *
find_vma_prepare(struct mm_struct *mm, unsigned long addr,
struct vm_area_struct **pprev, struct rb_node ***rb_link,
struct rb_node ** rb_parent)
{
struct vm_area_struct * vma;
struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
__rb_link = &mm->mm_rb.rb_node;
rb_prev = __rb_parent = NULL;
vma = NULL;
while (*__rb_link) {
struct vm_area_struct *vma_tmp;
__rb_parent = *__rb_link;
vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
if (vma_tmp->vm_end > addr) {
vma = vma_tmp;
if (vma_tmp->vm_start <= addr)
return vma;
__rb_link = &__rb_parent->rb_left;
} else {
rb_prev = __rb_parent;
__rb_link = &__rb_parent->rb_right;
}
}
*pprev = NULL;
if (rb_prev)
*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
*rb_link = __rb_link;
*rb_parent = __rb_parent;
return vma;
}
static inline void
__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *prev, struct rb_node *rb_parent)
{
if (prev) {
vma->vm_next = prev->vm_next;
prev->vm_next = vma;
} else {
mm->mmap = vma;
if (rb_parent)
vma->vm_next = rb_entry(rb_parent,
struct vm_area_struct, vm_rb);
else
vma->vm_next = NULL;
}
}
void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
struct rb_node **rb_link, struct rb_node *rb_parent)
{
rb_link_node(&vma->vm_rb, rb_parent, rb_link);
rb_insert_color(&vma->vm_rb, &mm->mm_rb);
}
static inline void __vma_link_file(struct vm_area_struct *vma)
{
struct file * file;
file = vma->vm_file;
if (file) {
struct address_space *mapping = file->f_mapping;
if (vma->vm_flags & VM_DENYWRITE)
atomic_dec(&file->f_dentry->d_inode->i_writecount);
if (vma->vm_flags & VM_SHARED)
list_add_tail(&vma->shared, &mapping->i_mmap_shared);
else
list_add_tail(&vma->shared, &mapping->i_mmap);
}
}
static void
__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *prev, struct rb_node **rb_link,
struct rb_node *rb_parent)
{
__vma_link_list(mm, vma, prev, rb_parent);
__vma_link_rb(mm, vma, rb_link, rb_parent);
__vma_link_file(vma);
}
static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *prev, struct rb_node **rb_link,
struct rb_node *rb_parent)
{
struct address_space *mapping = NULL;
if (vma->vm_file)
mapping = vma->vm_file->f_mapping;
if (mapping)
down(&mapping->i_shared_sem);
spin_lock(&mm->page_table_lock);
__vma_link(mm, vma, prev, rb_link, rb_parent);
spin_unlock(&mm->page_table_lock);
if (mapping)
up(&mapping->i_shared_sem);
mark_mm_hugetlb(mm, vma);
mm->map_count++;
validate_mm(mm);
}
/*
* Insert vm structure into process list sorted by address and into the inode's
* i_mmap ring. The caller should hold mm->page_table_lock and
* ->f_mappping->i_shared_sem if vm_file is non-NULL.
*/
static void
__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
{
struct vm_area_struct * __vma, * prev;
struct rb_node ** rb_link, * rb_parent;
__vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
if (__vma && __vma->vm_start < vma->vm_end)
BUG();
__vma_link(mm, vma, prev, rb_link, rb_parent);
mark_mm_hugetlb(mm, vma);
mm->map_count++;
validate_mm(mm);
}
/*
* If the vma has a ->close operation then the driver probably needs to release
* per-vma resources, so we don't attempt to merge those.
*/
#define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED)
static inline int is_mergeable_vma(struct vm_area_struct *vma,
struct file *file, unsigned long vm_flags)
{
if (vma->vm_ops && vma->vm_ops->close)
return 0;
if (vma->vm_file != file)
return 0;
if (vma->vm_flags != vm_flags)
return 0;
if (vma->vm_private_data)
return 0;
return 1;
}
/*
* Return true if we can merge this (vm_flags,file,vm_pgoff,size)
* in front of (at a lower virtual address and file offset than) the vma.
*
* We don't check here for the merged mmap wrapping around the end of pagecache
* indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
* wrap, nor mmaps which cover the final page at index -1UL.
*/
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
struct file *file, unsigned long vm_pgoff, unsigned long size)
{
if (is_mergeable_vma(vma, file, vm_flags)) {
if (!file)
return 1; /* anon mapping */
if (vma->vm_pgoff == vm_pgoff + size)
return 1;
}
return 0;
}
/*
* Return true if we can merge this (vm_flags,file,vm_pgoff)
* beyond (at a higher virtual address and file offset than) the vma.
*/
static int
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
struct file *file, unsigned long vm_pgoff)
{
if (is_mergeable_vma(vma, file, vm_flags)) {
unsigned long vma_size;
if (!file)
return 1; /* anon mapping */
vma_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
if (vma->vm_pgoff + vma_size == vm_pgoff)
return 1;
}
return 0;
}
/*
* Given a new mapping request (addr,end,vm_flags,file,pgoff), figure out
* whether that can be merged with its predecessor or its successor. Or
* both (it neatly fills a hole).
*/
static int vma_merge(struct mm_struct *mm, struct vm_area_struct *prev,
struct rb_node *rb_parent, unsigned long addr,
unsigned long end, unsigned long vm_flags,
struct file *file, unsigned long pgoff)
{
spinlock_t *lock = &mm->page_table_lock;
struct inode *inode = file ? file->f_dentry->d_inode : NULL;
struct semaphore *i_shared_sem;
/*
* We later require that vma->vm_flags == vm_flags, so this tests
* vma->vm_flags & VM_SPECIAL, too.
*/
if (vm_flags & VM_SPECIAL)
return 0;
i_shared_sem = file ? &file->f_mapping->i_shared_sem : NULL;
if (!prev) {
prev = rb_entry(rb_parent, struct vm_area_struct, vm_rb);
goto merge_next;
}
/*
* Can it merge with the predecessor?
*/
if (prev->vm_end == addr &&
is_mergeable_vma(prev, file, vm_flags) &&
can_vma_merge_after(prev, vm_flags, file, pgoff)) {
struct vm_area_struct *next;
int need_up = 0;
if (unlikely(file && prev->vm_next &&
prev->vm_next->vm_file == file)) {
down(i_shared_sem);
need_up = 1;
}
spin_lock(lock);
prev->vm_end = end;
/*
* OK, it did. Can we now merge in the successor as well?
*/
next = prev->vm_next;
if (next && prev->vm_end == next->vm_start &&
can_vma_merge_before(next, vm_flags, file,
pgoff, (end - addr) >> PAGE_SHIFT)) {
prev->vm_end = next->vm_end;
__vma_unlink(mm, next, prev);
__remove_shared_vm_struct(next, inode);
spin_unlock(lock);
if (need_up)
up(i_shared_sem);
if (file)
fput(file);
mm->map_count--;
kmem_cache_free(vm_area_cachep, next);
return 1;
}
spin_unlock(lock);
if (need_up)
up(i_shared_sem);
return 1;
}
/*
* Can this new request be merged in front of prev->vm_next?
*/
prev = prev->vm_next;
if (prev) {
merge_next:
if (!can_vma_merge_before(prev, vm_flags, file,
pgoff, (end - addr) >> PAGE_SHIFT))
return 0;
if (end == prev->vm_start) {
if (file)
down(i_shared_sem);
spin_lock(lock);
prev->vm_start = addr;
prev->vm_pgoff -= (end - addr) >> PAGE_SHIFT;
spin_unlock(lock);
if (file)
up(i_shared_sem);
return 1;
}
}
return 0;
}
/*
* The caller must hold down_write(current->mm->mmap_sem).
*/
unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
unsigned long len, unsigned long prot,
unsigned long flags, unsigned long pgoff)
{
struct mm_struct * mm = current->mm;
struct vm_area_struct * vma, * prev;
struct inode *inode;
unsigned int vm_flags;
int correct_wcount = 0;
int error;
struct rb_node ** rb_link, * rb_parent;
unsigned long charged = 0;
if (file) {
if (!file->f_op || !file->f_op->mmap)
return -ENODEV;
if ((prot & PROT_EXEC) && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
return -EPERM;
}
if (!len)
return addr;
/* Careful about overflows.. */
len = PAGE_ALIGN(len);
if (!len || len > TASK_SIZE)
return -EINVAL;
/* offset overflow? */
if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
return -EINVAL;
/* Too many mappings? */
if (mm->map_count > MAX_MAP_COUNT)
return -ENOMEM;
/* Obtain the address to map to. we verify (or select) it and ensure
* that it represents a valid section of the address space.
*/
addr = get_unmapped_area(file, addr, len, pgoff, flags);
if (addr & ~PAGE_MASK)
return addr;
/* Do simple checking here so the lower-level routines won't have
* to. we assume access permissions have been handled by the open
* of the memory object, so we don't do any here.
*/
vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
if (flags & MAP_LOCKED) {
if (!capable(CAP_IPC_LOCK))
return -EPERM;
vm_flags |= VM_LOCKED;
}
/* mlock MCL_FUTURE? */
if (vm_flags & VM_LOCKED) {
unsigned long locked = mm->locked_vm << PAGE_SHIFT;
locked += len;
if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur)
return -EAGAIN;
}
inode = file ? file->f_dentry->d_inode : NULL;
if (file) {
switch (flags & MAP_TYPE) {
case MAP_SHARED:
if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
return -EACCES;
/*
* Make sure we don't allow writing to an append-only
* file..
*/
if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
return -EACCES;
/*
* Make sure there are no mandatory locks on the file.
*/
if (locks_verify_locked(inode))
return -EAGAIN;
vm_flags |= VM_SHARED | VM_MAYSHARE;
if (!(file->f_mode & FMODE_WRITE))
vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
/* fall through */
case MAP_PRIVATE:
if (!(file->f_mode & FMODE_READ))
return -EACCES;
break;
default:
return -EINVAL;
}
} else {
vm_flags |= VM_SHARED | VM_MAYSHARE;
switch (flags & MAP_TYPE) {
default:
return -EINVAL;
case MAP_PRIVATE:
vm_flags &= ~(VM_SHARED | VM_MAYSHARE);
/* fall through */
case MAP_SHARED:
break;
}
}
error = security_file_mmap(file, prot, flags);
if (error)
return error;
/* Clear old maps */
error = -ENOMEM;
munmap_back:
vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
if (vma && vma->vm_start < addr + len) {
if (do_munmap(mm, addr, len))
return -ENOMEM;
goto munmap_back;
}
/* Check against address space limit. */
if ((mm->total_vm << PAGE_SHIFT) + len
> current->rlim[RLIMIT_AS].rlim_cur)
return -ENOMEM;
if (!(flags & MAP_NORESERVE) || sysctl_overcommit_memory > 1) {
if (vm_flags & VM_SHARED) {
/* Check memory availability in shmem_file_setup? */
vm_flags |= VM_ACCOUNT;
} else if (vm_flags & VM_WRITE) {
/*
* Private writable mapping: check memory availability
*/
charged = len >> PAGE_SHIFT;
if (security_vm_enough_memory(charged))
return -ENOMEM;
vm_flags |= VM_ACCOUNT;
}
}
/* Can we just expand an old anonymous mapping? */
if (!file && !(vm_flags & VM_SHARED) && rb_parent)
if (vma_merge(mm, prev, rb_parent, addr, addr + len,
vm_flags, NULL, 0))
goto out;
/*
* Determine the object being mapped and call the appropriate
* specific mapper. the address has already been validated, but
* not unmapped, but the maps are removed from the list.
*/
vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
error = -ENOMEM;
if (!vma)
goto unacct_error;
vma->vm_mm = mm;
vma->vm_start = addr;
vma->vm_end = addr + len;
vma->vm_flags = vm_flags;
vma->vm_page_prot = protection_map[vm_flags & 0x0f];
vma->vm_ops = NULL;
vma->vm_pgoff = pgoff;
vma->vm_file = NULL;
vma->vm_private_data = NULL;
vma->vm_next = NULL;
INIT_LIST_HEAD(&vma->shared);
if (file) {
error = -EINVAL;
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
goto free_vma;
if (vm_flags & VM_DENYWRITE) {
error = deny_write_access(file);
if (error)
goto free_vma;
correct_wcount = 1;
}
vma->vm_file = file;
get_file(file);
error = file->f_op->mmap(file, vma);
if (error)
goto unmap_and_free_vma;
} else if (vm_flags & VM_SHARED) {
error = shmem_zero_setup(vma);
if (error)
goto free_vma;
}
/* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
* shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
* that memory reservation must be checked; but that reservation
* belongs to shared memory object, not to vma: so now clear it.
*/
if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
vma->vm_flags &= ~VM_ACCOUNT;
/* Can addr have changed??
*
* Answer: Yes, several device drivers can do it in their
* f_op->mmap method. -DaveM
*/
addr = vma->vm_start;
if (!file || !rb_parent || !vma_merge(mm, prev, rb_parent, addr,
addr + len, vma->vm_flags, file, pgoff)) {
vma_link(mm, vma, prev, rb_link, rb_parent);
if (correct_wcount)
atomic_inc(&inode->i_writecount);
} else {
if (file) {
if (correct_wcount)
atomic_inc(&inode->i_writecount);
fput(file);
}
kmem_cache_free(vm_area_cachep, vma);
}
out:
mm->total_vm += len >> PAGE_SHIFT;
if (vm_flags & VM_LOCKED) {
mm->locked_vm += len >> PAGE_SHIFT;
make_pages_present(addr, addr + len);
}
if (flags & MAP_POPULATE) {
up_write(&mm->mmap_sem);
sys_remap_file_pages(addr, len, prot,
pgoff, flags & MAP_NONBLOCK);
down_write(&mm->mmap_sem);
}
return addr;
unmap_and_free_vma:
if (correct_wcount)
atomic_inc(&inode->i_writecount);
vma->vm_file = NULL;
fput(file);
/* Undo any partial mapping done by a device driver. */
zap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start);
free_vma:
kmem_cache_free(vm_area_cachep, vma);
unacct_error:
if (charged)
vm_unacct_memory(charged);
return error;
}
EXPORT_SYMBOL(do_mmap_pgoff);
/* Get an address range which is currently unmapped.
* For shmat() with addr=0.
*
* Ugly calling convention alert:
* Return value with the low bits set means error value,
* ie
* if (ret & ~PAGE_MASK)
* error = ret;
*
* This function "knows" that -ENOMEM has the bits set.
*/
#ifndef HAVE_ARCH_UNMAPPED_AREA
static inline unsigned long
arch_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long start_addr;
if (len > TASK_SIZE)
return -ENOMEM;
if (addr) {
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
(!vma || addr + len <= vma->vm_start))
return addr;
}
start_addr = addr = mm->free_area_cache;
full_search:
for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
/* At this point: (!vma || addr < vma->vm_end). */
if (TASK_SIZE - len < addr) {
/*
* Start a new search - just in case we missed
* some holes.
*/
if (start_addr != TASK_UNMAPPED_BASE) {
start_addr = addr = TASK_UNMAPPED_BASE;
goto full_search;
}
return -ENOMEM;
}
if (!vma || addr + len <= vma->vm_start) {
/*
* Remember the place where we stopped the search:
*/
mm->free_area_cache = addr + len;
return addr;
}
addr = vma->vm_end;
}
}
#else
extern unsigned long
arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
unsigned long, unsigned long);
#endif
unsigned long
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
unsigned long pgoff, unsigned long flags)
{
if (flags & MAP_FIXED) {
unsigned long ret;
if (addr > TASK_SIZE - len)
return -ENOMEM;
if (addr & ~PAGE_MASK)
return -EINVAL;
if (file && is_file_hugepages(file)) {
/*
* Make sure that addr and length are properly aligned.
*/
ret = is_aligned_hugepage_range(addr, len);
} else {
/*
* Ensure that a normal request is not falling in a
* reserved hugepage range. For some archs like IA-64,
* there is a separate region for hugepages.
*/
ret = is_hugepage_only_range(addr, len);
}
if (ret)
return -EINVAL;
return addr;
}
if (file && file->f_op && file->f_op->get_unmapped_area)
return file->f_op->get_unmapped_area(file, addr, len,
pgoff, flags);
return arch_get_unmapped_area(file, addr, len, pgoff, flags);
}
EXPORT_SYMBOL(get_unmapped_area);
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
{
struct vm_area_struct *vma = NULL;
if (mm) {
/* Check the cache first. */
/* (Cache hit rate is typically around 35%.) */
vma = mm->mmap_cache;
if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
struct rb_node * rb_node;
rb_node = mm->mm_rb.rb_node;
vma = NULL;
while (rb_node) {
struct vm_area_struct * vma_tmp;
vma_tmp = rb_entry(rb_node,
struct vm_area_struct, vm_rb);
if (vma_tmp->vm_end > addr) {
vma = vma_tmp;
if (vma_tmp->vm_start <= addr)
break;
rb_node = rb_node->rb_left;
} else
rb_node = rb_node->rb_right;
}
if (vma)
mm->mmap_cache = vma;
}
}
return vma;
}
EXPORT_SYMBOL(find_vma);
/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
struct vm_area_struct *
find_vma_prev(struct mm_struct *mm, unsigned long addr,
struct vm_area_struct **pprev)
{
struct vm_area_struct *vma = NULL, *prev = NULL;
struct rb_node * rb_node;
if (!mm)
goto out;
/* Guard against addr being lower than the first VMA */
vma = mm->mmap;
/* Go through the RB tree quickly. */
rb_node = mm->mm_rb.rb_node;
while (rb_node) {
struct vm_area_struct *vma_tmp;
vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
if (addr < vma_tmp->vm_end) {
rb_node = rb_node->rb_left;
} else {
prev = vma_tmp;
if (!prev->vm_next || (addr < prev->vm_next->vm_end))
break;
rb_node = rb_node->rb_right;
}
}
out:
*pprev = prev;
return prev ? prev->vm_next : vma;
}
#ifdef CONFIG_STACK_GROWSUP
/*
* vma is the first one with address > vma->vm_end. Have to extend vma.
*/
int expand_stack(struct vm_area_struct * vma, unsigned long address)
{
unsigned long grow;
if (!(vma->vm_flags & VM_GROWSUP))
return -EFAULT;
/*
* vma->vm_start/vm_end cannot change under us because the caller
* is required to hold the mmap_sem in read mode. We need to get
* the spinlock only before relocating the vma range ourself.
*/
address += 4 + PAGE_SIZE - 1;
address &= PAGE_MASK;
spin_lock(&vma->vm_mm->page_table_lock);
grow = (address - vma->vm_end) >> PAGE_SHIFT;
/* Overcommit.. */
if (security_vm_enough_memory(grow)) {
spin_unlock(&vma->vm_mm->page_table_lock);
return -ENOMEM;
}
if (address - vma->vm_start > current->rlim[RLIMIT_STACK].rlim_cur ||
((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) >
current->rlim[RLIMIT_AS].rlim_cur) {
spin_unlock(&vma->vm_mm->page_table_lock);
vm_unacct_memory(grow);
return -ENOMEM;
}
vma->vm_end = address;
vma->vm_mm->total_vm += grow;
if (vma->vm_flags & VM_LOCKED)
vma->vm_mm->locked_vm += grow;
spin_unlock(&vma->vm_mm->page_table_lock);
return 0;
}
struct vm_area_struct *
find_extend_vma(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma, *prev;
addr &= PAGE_MASK;
vma = find_vma_prev(mm, addr, &prev);
if (vma && (vma->vm_start <= addr))
return vma;
if (!prev || expand_stack(prev, addr))
return NULL;
if (prev->vm_flags & VM_LOCKED) {
make_pages_present(addr, prev->vm_end);
}
return prev;
}
#else
/*
* vma is the first one with address < vma->vm_start. Have to extend vma.
*/
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
unsigned long grow;
/*
* vma->vm_start/vm_end cannot change under us because the caller
* is required to hold the mmap_sem in read mode. We need to get
* the spinlock only before relocating the vma range ourself.
*/
address &= PAGE_MASK;
spin_lock(&vma->vm_mm->page_table_lock);
grow = (vma->vm_start - address) >> PAGE_SHIFT;
/* Overcommit.. */
if (security_vm_enough_memory(grow)) {
spin_unlock(&vma->vm_mm->page_table_lock);
return -ENOMEM;
}
if (vma->vm_end - address > current->rlim[RLIMIT_STACK].rlim_cur ||
((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) >
current->rlim[RLIMIT_AS].rlim_cur) {
spin_unlock(&vma->vm_mm->page_table_lock);
vm_unacct_memory(grow);
return -ENOMEM;
}
vma->vm_start = address;
vma->vm_pgoff -= grow;
vma->vm_mm->total_vm += grow;
if (vma->vm_flags & VM_LOCKED)
vma->vm_mm->locked_vm += grow;
spin_unlock(&vma->vm_mm->page_table_lock);
return 0;
}
struct vm_area_struct *
find_extend_vma(struct mm_struct * mm, unsigned long addr)
{
struct vm_area_struct * vma;
unsigned long start;
addr &= PAGE_MASK;
vma = find_vma(mm,addr);
if (!vma)
return NULL;
if (vma->vm_start <= addr)
return vma;
if (!(vma->vm_flags & VM_GROWSDOWN))
return NULL;
start = vma->vm_start;
if (expand_stack(vma, addr))
return NULL;
if (vma->vm_flags & VM_LOCKED) {
make_pages_present(addr, start);
}
return vma;
}
#endif
/*
* Try to free as many page directory entries as we can,
* without having to work very hard at actually scanning
* the page tables themselves.
*
* Right now we try to free page tables if we have a nice
* PGDIR-aligned area that got free'd up. We could be more
* granular if we want to, but this is fast and simple,
* and covers the bad cases.
*
* "prev", if it exists, points to a vma before the one
* we just free'd - but there's no telling how much before.
*/
static void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *prev,
unsigned long start, unsigned long end)
{
unsigned long first = start & PGDIR_MASK;
unsigned long last = end + PGDIR_SIZE - 1;
unsigned long start_index, end_index;
struct mm_struct *mm = tlb->mm;
if (!prev) {
prev = mm->mmap;
if (!prev)
goto no_mmaps;
if (prev->vm_end > start) {
if (last > prev->vm_start)
last = prev->vm_start;
goto no_mmaps;
}
}
for (;;) {
struct vm_area_struct *next = prev->vm_next;
if (next) {
if (next->vm_start < start) {
prev = next;
continue;
}
if (last > next->vm_start)
last = next->vm_start;
}
if (prev->vm_end > first)
first = prev->vm_end + PGDIR_SIZE - 1;
break;
}
no_mmaps:
if (last < first) /* for arches with discontiguous pgd indices */
return;
/*
* If the PGD bits are not consecutive in the virtual address, the
* old method of shifting the VA >> by PGDIR_SHIFT doesn't work.
*/
start_index = pgd_index(first);
if (start_index < FIRST_USER_PGD_NR)
start_index = FIRST_USER_PGD_NR;
end_index = pgd_index(last);
if (end_index > start_index) {
clear_page_tables(tlb, start_index, end_index - start_index);
flush_tlb_pgtables(mm, first & PGDIR_MASK, last & PGDIR_MASK);
}
}
/* Normal function to fix up a mapping
* This function is the default for when an area has no specific
* function. This may be used as part of a more specific routine.
*
* By the time this function is called, the area struct has been
* removed from the process mapping list.
*/
static void unmap_vma(struct mm_struct *mm, struct vm_area_struct *area)
{
size_t len = area->vm_end - area->vm_start;
area->vm_mm->total_vm -= len >> PAGE_SHIFT;
if (area->vm_flags & VM_LOCKED)
area->vm_mm->locked_vm -= len >> PAGE_SHIFT;
/*
* Is this a new hole at the lowest possible address?
*/
if (area->vm_start >= TASK_UNMAPPED_BASE &&
area->vm_start < area->vm_mm->free_area_cache)
area->vm_mm->free_area_cache = area->vm_start;
remove_shared_vm_struct(area);
if (area->vm_ops && area->vm_ops->close)
area->vm_ops->close(area);
if (area->vm_file)
fput(area->vm_file);
kmem_cache_free(vm_area_cachep, area);
}
/*
* Update the VMA and inode share lists.
*
* Ok - we have the memory areas we should free on the 'free' list,
* so release them, and do the vma updates.
*/
static void unmap_vma_list(struct mm_struct *mm,
struct vm_area_struct *mpnt)
{
do {
struct vm_area_struct *next = mpnt->vm_next;
unmap_vma(mm, mpnt);
mpnt = next;
} while (mpnt != NULL);
validate_mm(mm);
}
/*
* Get rid of page table information in the indicated region.
*
* Called with the page table lock held.
*/
static void unmap_region(struct mm_struct *mm,
struct vm_area_struct *vma,
struct vm_area_struct *prev,
unsigned long start,
unsigned long end)
{
struct mmu_gather *tlb;
unsigned long nr_accounted = 0;
lru_add_drain();
tlb = tlb_gather_mmu(mm, 0);
unmap_vmas(&tlb, mm, vma, start, end, &nr_accounted);
vm_unacct_memory(nr_accounted);
if (is_hugepage_only_range(start, end - start))
hugetlb_free_pgtables(tlb, prev, start, end);
else
free_pgtables(tlb, prev, start, end);
tlb_finish_mmu(tlb, start, end);
}
/*
* Create a list of vma's touched by the unmap, removing them from the mm's
* vma list as we go..
*
* Called with the page_table_lock held.
*/
static void
detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *prev, unsigned long end)
{
struct vm_area_struct **insertion_point;
struct vm_area_struct *tail_vma = NULL;
insertion_point = (prev ? &prev->vm_next : &mm->mmap);
do {
rb_erase(&vma->vm_rb, &mm->mm_rb);
mm->map_count--;
tail_vma = vma;
vma = vma->vm_next;
} while (vma && vma->vm_start < end);
*insertion_point = vma;
tail_vma->vm_next = NULL;
mm->mmap_cache = NULL; /* Kill the cache. */
}
/*
* Split a vma into two pieces at address 'addr', a new vma is allocated
* either for the first part or the 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 address_space *mapping = NULL;
if (mm->map_count >= MAX_MAP_COUNT)
return -ENOMEM;
new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!new)
return -ENOMEM;
/* most fields are the same, copy all, and then fixup */
*new = *vma;
INIT_LIST_HEAD(&new->shared);
if (new_below)
new->vm_end = addr;
else {
new->vm_start = addr;
new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
}
if (new->vm_file)
get_file(new->vm_file);
if (new->vm_ops && new->vm_ops->open)
new->vm_ops->open(new);
if (vma->vm_file)
mapping = vma->vm_file->f_mapping;
if (mapping)
down(&mapping->i_shared_sem);
spin_lock(&mm->page_table_lock);
if (new_below) {
vma->vm_start = addr;
vma->vm_pgoff += ((addr - new->vm_start) >> PAGE_SHIFT);
} else
vma->vm_end = addr;
__insert_vm_struct(mm, new);
spin_unlock(&mm->page_table_lock);
if (mapping)
up(&mapping->i_shared_sem);
return 0;
}
/* Munmap is split into 2 main parts -- this part which finds
* what needs doing, and the areas themselves, which do the
* work. This now handles partial unmappings.
* Jeremy Fitzhardinge <jeremy@goop.org>
*/
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
unsigned long end;
struct vm_area_struct *mpnt, *prev, *last;
if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
return -EINVAL;
if ((len = PAGE_ALIGN(len)) == 0)
return -EINVAL;
/* Find the first overlapping VMA */
mpnt = find_vma_prev(mm, start, &prev);
if (!mpnt)
return 0;
/* we have start < mpnt->vm_end */
if (is_vm_hugetlb_page(mpnt)) {
int ret = is_aligned_hugepage_range(start, len);
if (ret)
return ret;
}
/* if it doesn't overlap, we have nothing.. */
end = start + len;
if (mpnt->vm_start >= end)
return 0;
/* Something will probably happen, so notify. */
if (mpnt->vm_file && (mpnt->vm_flags & VM_EXEC))
profile_exec_unmap(mm);
/*
* If we need to split any vma, do it now to save pain later.
*
* Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
* unmapped vm_area_struct will remain in use: so lower split_vma
* places tmp vma above, and higher split_vma places tmp vma below.
*/
if (start > mpnt->vm_start) {
if (split_vma(mm, mpnt, start, 0))
return -ENOMEM;
prev = mpnt;
}
/* Does it split the last one? */
last = find_vma(mm, end);
if (last && end > last->vm_start) {
if (split_vma(mm, last, end, 1))
return -ENOMEM;
}
mpnt = prev? prev->vm_next: mm->mmap;
/*
* Remove the vma's, and unmap the actual pages
*/
spin_lock(&mm->page_table_lock);
detach_vmas_to_be_unmapped(mm, mpnt, prev, end);
unmap_region(mm, mpnt, prev, start, end);
spin_unlock(&mm->page_table_lock);
/* Fix up all other VM information */
unmap_vma_list(mm, mpnt);
return 0;
}
EXPORT_SYMBOL(do_munmap);
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;
}
/*
* this is really a simplified "do_mmap". it only handles
* anonymous maps. eventually we may be able to do some
* brk-specific accounting here.
*/
unsigned long do_brk(unsigned long addr, unsigned long len)
{
struct mm_struct * mm = current->mm;
struct vm_area_struct * vma, * prev;
unsigned long flags;
struct rb_node ** rb_link, * rb_parent;
len = PAGE_ALIGN(len);
if (!len)
return addr;
if ((addr + len) > TASK_SIZE || (addr + len) < addr)
return -EINVAL;
/*
* mlock MCL_FUTURE?
*/
if (mm->def_flags & VM_LOCKED) {
unsigned long locked = mm->locked_vm << PAGE_SHIFT;
locked += len;
if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur)
return -EAGAIN;
}
/*
* Clear old maps. this also does some error checking for us
*/
munmap_back:
vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
if (vma && vma->vm_start < addr + len) {
if (do_munmap(mm, addr, len))
return -ENOMEM;
goto munmap_back;
}
/* Check against address space limits *after* clearing old maps... */
if ((mm->total_vm << PAGE_SHIFT) + len
> current->rlim[RLIMIT_AS].rlim_cur)
return -ENOMEM;
if (mm->map_count > MAX_MAP_COUNT)
return -ENOMEM;
if (security_vm_enough_memory(len >> PAGE_SHIFT))
return -ENOMEM;
flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
/* Can we just expand an old anonymous mapping? */
if (rb_parent && vma_merge(mm, prev, rb_parent, addr, addr + len,
flags, NULL, 0))
goto out;
/*
* create a vma struct for an anonymous mapping
*/
vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!vma) {
vm_unacct_memory(len >> PAGE_SHIFT);
return -ENOMEM;
}
vma->vm_mm = mm;
vma->vm_start = addr;
vma->vm_end = addr + len;
vma->vm_flags = flags;
vma->vm_page_prot = protection_map[flags & 0x0f];
vma->vm_ops = NULL;
vma->vm_pgoff = 0;
vma->vm_file = NULL;
vma->vm_private_data = NULL;
INIT_LIST_HEAD(&vma->shared);
vma_link(mm, vma, prev, rb_link, rb_parent);
out:
mm->total_vm += len >> PAGE_SHIFT;
if (flags & VM_LOCKED) {
mm->locked_vm += len >> PAGE_SHIFT;
make_pages_present(addr, addr + len);
}
return addr;
}
EXPORT_SYMBOL(do_brk);
/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
struct mmu_gather *tlb;
struct vm_area_struct *vma;
unsigned long nr_accounted = 0;
profile_exit_mmap(mm);
lru_add_drain();
spin_lock(&mm->page_table_lock);
tlb = tlb_gather_mmu(mm, 1);
flush_cache_mm(mm);
/* Use ~0UL here to ensure all VMAs in the mm are unmapped */
mm->map_count -= unmap_vmas(&tlb, mm, mm->mmap, 0,
~0UL, &nr_accounted);
vm_unacct_memory(nr_accounted);
BUG_ON(mm->map_count); /* This is just debugging */
clear_page_tables(tlb, FIRST_USER_PGD_NR, USER_PTRS_PER_PGD);
tlb_finish_mmu(tlb, 0, MM_VM_SIZE(mm));
vma = mm->mmap;
mm->mmap = mm->mmap_cache = NULL;
mm->mm_rb = RB_ROOT;
mm->rss = 0;
mm->total_vm = 0;
mm->locked_vm = 0;
spin_unlock(&mm->page_table_lock);
/*
* Walk the list again, actually closing and freeing it
* without holding any MM locks.
*/
while (vma) {
struct vm_area_struct *next = vma->vm_next;
remove_shared_vm_struct(vma);
if (vma->vm_ops) {
if (vma->vm_ops->close)
vma->vm_ops->close(vma);
}
if (vma->vm_file)
fput(vma->vm_file);
kmem_cache_free(vm_area_cachep, vma);
vma = next;
}
}
/* Insert vm structure into process list sorted by address
* and into the inode's i_mmap ring. If vm_file is non-NULL
* then i_shared_sem is taken here.
*/
void insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
{
struct vm_area_struct * __vma, * prev;
struct rb_node ** rb_link, * rb_parent;
__vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
if (__vma && __vma->vm_start < vma->vm_end)
BUG();
vma_link(mm, vma, prev, rb_link, rb_parent);
validate_mm(mm);
}
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