blob: d0999d73d60a2fa20960779a796bb05d30ee7a65 [file] [log] [blame]
/*
* linux/mm/mmap.c
*
* Written by obz.
*/
#include <linux/slab.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/swapctl.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.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;
int max_map_count = DEFAULT_MAX_MAP_COUNT;
/* Check that a process has enough memory to allocate a
* new virtual mapping.
*/
int vm_enough_memory(long pages)
{
/* Stupid algorithm to decide if we have enough memory: while
* simple, it hopefully works in most obvious cases.. Easy to
* fool it, but this should catch most mistakes.
*/
/* 23/11/98 NJC: Somewhat less stupid version of algorithm,
* which tries to do "TheRightThing". Instead of using half of
* (buffers+cache), use the minimum values. Allow an extra 2%
* of num_physpages for safety margin.
*/
unsigned long free;
/* Sometimes we want to use more memory than we have. */
if (sysctl_overcommit_memory)
return 1;
/* The page cache contains buffer pages these days.. */
free = atomic_read(&page_cache_size);
free += nr_free_pages();
free += nr_swap_pages;
/*
* This double-counts: the nrpages are both in the page-cache
* and in the swapper space. At the same time, this compensates
* for the swap-space over-allocation (ie "nr_swap_pages" being
* too small.
*/
free += swapper_space.nrpages;
/*
* The code below doesn't account for free space in the inode
* and dentry slab cache, slab cache fragmentation, inodes and
* dentries which will become freeable under VM load, etc.
* Lets just hope all these (complex) factors balance out...
*/
free += (dentry_stat.nr_unused * sizeof(struct dentry)) >> PAGE_SHIFT;
free += (inodes_stat.nr_unused * sizeof(struct inode)) >> PAGE_SHIFT;
return free > pages;
}
/* Remove one vm structure from the inode's i_mapping address space. */
static inline void __remove_shared_vm_struct(struct vm_area_struct *vma)
{
struct file * file = vma->vm_file;
if (file) {
struct inode *inode = file->f_dentry->d_inode;
if (vma->vm_flags & VM_DENYWRITE)
atomic_inc(&inode->i_writecount);
if(vma->vm_next_share)
vma->vm_next_share->vm_pprev_share = vma->vm_pprev_share;
*vma->vm_pprev_share = vma->vm_next_share;
}
}
static inline void remove_shared_vm_struct(struct vm_area_struct *vma)
{
lock_vma_mappings(vma);
__remove_shared_vm_struct(vma);
unlock_vma_mappings(vma);
}
void lock_vma_mappings(struct vm_area_struct *vma)
{
struct address_space *mapping;
mapping = NULL;
if (vma->vm_file)
mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
if (mapping)
spin_lock(&mapping->i_shared_lock);
}
void unlock_vma_mappings(struct vm_area_struct *vma)
{
struct address_space *mapping;
mapping = NULL;
if (vma->vm_file)
mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
if (mapping)
spin_unlock(&mapping->i_shared_lock);
}
/*
* 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;
/* Check if we have enough memory.. */
if (!vm_enough_memory((newbrk-oldbrk) >> PAGE_SHIFT))
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;
}
/* Combine the mmap "prot" and "flags" argument into one "vm_flags" used
* internally. Essentially, translate the "PROT_xxx" and "MAP_xxx" bits
* into "VM_xxx".
*/
static inline unsigned long calc_vm_flags(unsigned long prot, unsigned long flags)
{
#define _trans(x,bit1,bit2) \
((bit1==bit2)?(x&bit1):(x&bit1)?bit2:0)
unsigned long prot_bits, flag_bits;
prot_bits =
_trans(prot, PROT_READ, VM_READ) |
_trans(prot, PROT_WRITE, VM_WRITE) |
_trans(prot, PROT_EXEC, VM_EXEC);
flag_bits =
_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN) |
_trans(flags, MAP_DENYWRITE, VM_DENYWRITE) |
_trans(flags, MAP_EXECUTABLE, VM_EXECUTABLE);
return prot_bits | flag_bits;
#undef _trans
}
#ifdef DEBUG_MM_RB
static int browse_rb(rb_node_t * 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,
rb_node_t *** rb_link, rb_node_t ** rb_parent)
{
struct vm_area_struct * vma;
rb_node_t ** __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,
rb_node_t * 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;
}
}
static inline void __vma_link_rb(struct mm_struct * mm, struct vm_area_struct * vma,
rb_node_t ** rb_link, rb_node_t * 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 inode * inode = file->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
struct vm_area_struct **head;
if (vma->vm_flags & VM_DENYWRITE)
atomic_dec(&inode->i_writecount);
head = &mapping->i_mmap;
if (vma->vm_flags & VM_SHARED)
head = &mapping->i_mmap_shared;
/* insert vma into inode's share list */
if((vma->vm_next_share = *head) != NULL)
(*head)->vm_pprev_share = &vma->vm_next_share;
*head = vma;
vma->vm_pprev_share = head;
}
}
static void __vma_link(struct mm_struct * mm, struct vm_area_struct * vma, struct vm_area_struct * prev,
rb_node_t ** rb_link, rb_node_t * rb_parent)
{
__vma_link_list(mm, vma, prev, rb_parent);
__vma_link_rb(mm, vma, rb_link, rb_parent);
__vma_link_file(vma);
}
static inline void vma_link(struct mm_struct * mm, struct vm_area_struct * vma, struct vm_area_struct * prev,
rb_node_t ** rb_link, rb_node_t * rb_parent)
{
lock_vma_mappings(vma);
spin_lock(&mm->page_table_lock);
__vma_link(mm, vma, prev, rb_link, rb_parent);
spin_unlock(&mm->page_table_lock);
unlock_vma_mappings(vma);
mm->map_count++;
validate_mm(mm);
}
static int vma_merge(struct mm_struct * mm, struct vm_area_struct * prev,
rb_node_t * rb_parent, unsigned long addr, unsigned long end, unsigned long vm_flags)
{
spinlock_t * lock = &mm->page_table_lock;
if (!prev) {
prev = rb_entry(rb_parent, struct vm_area_struct, vm_rb);
goto merge_next;
}
if (prev->vm_end == addr && can_vma_merge(prev, vm_flags)) {
struct vm_area_struct * next;
spin_lock(lock);
prev->vm_end = end;
next = prev->vm_next;
if (next && prev->vm_end == next->vm_start && can_vma_merge(next, vm_flags)) {
prev->vm_end = next->vm_end;
__vma_unlink(mm, next, prev);
spin_unlock(lock);
mm->map_count--;
kmem_cache_free(vm_area_cachep, next);
return 1;
}
spin_unlock(lock);
return 1;
}
prev = prev->vm_next;
if (prev) {
merge_next:
if (!can_vma_merge(prev, vm_flags))
return 0;
if (end == prev->vm_start) {
spin_lock(lock);
prev->vm_start = addr;
spin_unlock(lock);
return 1;
}
}
return 0;
}
unsigned long do_mmap_pgoff(struct mm_struct *mm, struct file * file,
unsigned long addr, unsigned long len,
unsigned long prot, unsigned long flags,
unsigned long pgoff)
{
struct vm_area_struct * vma, * prev;
unsigned int vm_flags;
int correct_wcount = 0;
int error;
rb_node_t ** rb_link, * rb_parent;
if (file && (!file->f_op || !file->f_op->mmap))
return -ENODEV;
if (!len)
return addr;
len = PAGE_ALIGN(len);
if (len > TASK_SIZE || len == 0)
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_flags(prot,flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
/* 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;
}
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(file->f_dentry->d_inode) && (file->f_mode & FMODE_WRITE))
return -EACCES;
/* make sure there are no mandatory locks on the file. */
if (locks_verify_locked(file->f_dentry->d_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;
}
}
/* Clear old maps */
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;
/* Private writable mapping? Check memory availability.. */
if ((vm_flags & (VM_SHARED | VM_WRITE)) == VM_WRITE &&
!(flags & MAP_NORESERVE) &&
!vm_enough_memory(len >> PAGE_SHIFT))
return -ENOMEM;
/* 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))
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);
if (!vma)
return -ENOMEM;
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_raend = 0;
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 (flags & MAP_SHARED) {
error = shmem_zero_setup(vma);
if (error)
goto free_vma;
}
/* Can addr have changed??
*
* Answer: Yes, several device drivers can do it in their
* f_op->mmap method. -DaveM
*/
if (addr != vma->vm_start) {
/*
* It is a bit too late to pretend changing the virtual
* area of the mapping, we just corrupted userspace
* in the do_munmap, so FIXME (not in 2.4 to avoid breaking
* the driver API).
*/
struct vm_area_struct * stale_vma;
/* Since addr changed, we rely on the mmap op to prevent
* collisions with existing vmas and just use find_vma_prepare
* to update the tree pointers.
*/
addr = vma->vm_start;
stale_vma = find_vma_prepare(mm, addr, &prev,
&rb_link, &rb_parent);
/*
* Make sure the lowlevel driver did its job right.
*/
if (unlikely(stale_vma && stale_vma->vm_start < vma->vm_end)) {
printk(KERN_ERR "buggy mmap operation: [<%p>]\n",
file ? file->f_op->mmap : NULL);
BUG();
}
}
vma_link(mm, vma, prev, rb_link, rb_parent);
if (correct_wcount)
atomic_inc(&file->f_dentry->d_inode->i_writecount);
out:
mm->total_vm += len >> PAGE_SHIFT;
if (vm_flags & VM_LOCKED) {
mm->locked_vm += len >> PAGE_SHIFT;
make_pages_present(addr, addr + len);
}
return addr;
unmap_and_free_vma:
if (correct_wcount)
atomic_inc(&file->f_dentry->d_inode->i_writecount);
vma->vm_file = NULL;
fput(file);
/* Undo any partial mapping done by a device driver. */
zap_page_range(mm, vma->vm_start, vma->vm_end - vma->vm_start);
free_vma:
kmem_cache_free(vm_area_cachep, vma);
return error;
}
/* 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 vm_area_struct *vma;
if (len > TASK_SIZE)
return -ENOMEM;
if (addr) {
addr = PAGE_ALIGN(addr);
vma = find_vma(current->mm, addr);
if (TASK_SIZE - len >= addr &&
(!vma || addr + len <= vma->vm_start))
return addr;
}
addr = PAGE_ALIGN(TASK_UNMAPPED_BASE);
for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
/* At this point: (!vma || addr < vma->vm_end). */
if (TASK_SIZE - len < addr)
return -ENOMEM;
if (!vma || addr + len <= vma->vm_start)
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) {
if (addr > TASK_SIZE - len)
return -ENOMEM;
if (addr & ~PAGE_MASK)
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);
}
/* 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)) {
rb_node_t * 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;
}
/* 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)
{
if (mm) {
/* Go through the RB tree quickly. */
struct vm_area_struct * vma;
rb_node_t * rb_node, * rb_last_right, * rb_prev;
rb_node = mm->mm_rb.rb_node;
rb_last_right = rb_prev = NULL;
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;
rb_prev = rb_last_right;
if (vma_tmp->vm_start <= addr)
break;
rb_node = rb_node->rb_left;
} else {
rb_last_right = rb_node;
rb_node = rb_node->rb_right;
}
}
if (vma) {
if (vma->vm_rb.rb_left) {
rb_prev = vma->vm_rb.rb_left;
while (rb_prev->rb_right)
rb_prev = rb_prev->rb_right;
}
*pprev = NULL;
if (rb_prev)
*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
if ((rb_prev ? (*pprev)->vm_next : mm->mmap) != vma)
BUG();
return vma;
}
}
*pprev = NULL;
return NULL;
}
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;
}
/* 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.
* This function works out what part of an area is affected and
* adjusts the mapping information. Since the actual page
* manipulation is done in do_mmap(), none need be done here,
* though it would probably be more appropriate.
*
* By the time this function is called, the area struct has been
* removed from the process mapping list, so it needs to be
* reinserted if necessary.
*
* The 4 main cases are:
* Unmapping the whole area
* Unmapping from the start of the segment to a point in it
* Unmapping from an intermediate point to the end
* Unmapping between to intermediate points, making a hole.
*
* Case 4 involves the creation of 2 new areas, for each side of
* the hole. If possible, we reuse the existing area rather than
* allocate a new one, and the return indicates whether the old
* area was reused.
*/
static struct vm_area_struct * unmap_fixup(struct mm_struct *mm,
struct vm_area_struct *area, unsigned long addr, size_t len,
struct vm_area_struct *extra)
{
struct vm_area_struct *mpnt;
unsigned long end = addr + len;
area->vm_mm->total_vm -= len >> PAGE_SHIFT;
if (area->vm_flags & VM_LOCKED)
area->vm_mm->locked_vm -= len >> PAGE_SHIFT;
/* Unmapping the whole area. */
if (addr == area->vm_start && end == area->vm_end) {
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);
return extra;
}
/* Work out to one of the ends. */
if (end == area->vm_end) {
/*
* here area isn't visible to the semaphore-less readers
* so we don't need to update it under the spinlock.
*/
area->vm_end = addr;
lock_vma_mappings(area);
spin_lock(&mm->page_table_lock);
} else if (addr == area->vm_start) {
area->vm_pgoff += (end - area->vm_start) >> PAGE_SHIFT;
/* same locking considerations of the above case */
area->vm_start = end;
lock_vma_mappings(area);
spin_lock(&mm->page_table_lock);
} else {
/* Unmapping a hole: area->vm_start < addr <= end < area->vm_end */
/* Add end mapping -- leave beginning for below */
mpnt = extra;
extra = NULL;
mpnt->vm_mm = area->vm_mm;
mpnt->vm_start = end;
mpnt->vm_end = area->vm_end;
mpnt->vm_page_prot = area->vm_page_prot;
mpnt->vm_flags = area->vm_flags;
mpnt->vm_raend = 0;
mpnt->vm_ops = area->vm_ops;
mpnt->vm_pgoff = area->vm_pgoff + ((end - area->vm_start) >> PAGE_SHIFT);
mpnt->vm_file = area->vm_file;
mpnt->vm_private_data = area->vm_private_data;
if (mpnt->vm_file)
get_file(mpnt->vm_file);
if (mpnt->vm_ops && mpnt->vm_ops->open)
mpnt->vm_ops->open(mpnt);
area->vm_end = addr; /* Truncate area */
/* Because mpnt->vm_file == area->vm_file this locks
* things correctly.
*/
lock_vma_mappings(area);
spin_lock(&mm->page_table_lock);
__insert_vm_struct(mm, mpnt);
}
__insert_vm_struct(mm, area);
spin_unlock(&mm->page_table_lock);
unlock_vma_mappings(area);
return extra;
}
/*
* 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 mm_struct * mm, 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;
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)
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);
end_index = pgd_index(last);
if (end_index > start_index) {
clear_page_tables(mm, start_index, end_index - start_index);
flush_tlb_pgtables(mm, first & PGDIR_MASK, last & PGDIR_MASK);
}
}
/* 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 Fitzhardine <jeremy@sw.oz.au>
*/
int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
{
struct vm_area_struct *mpnt, *prev, **npp, *free, *extra;
if ((addr & ~PAGE_MASK) || addr > TASK_SIZE || len > TASK_SIZE-addr)
return -EINVAL;
if ((len = PAGE_ALIGN(len)) == 0)
return -EINVAL;
/* Check if this memory area is ok - put it on the temporary
* list if so.. The checks here are pretty simple --
* every area affected in some way (by any overlap) is put
* on the list. If nothing is put on, nothing is affected.
*/
mpnt = find_vma_prev(mm, addr, &prev);
if (!mpnt)
return 0;
/* we have addr < mpnt->vm_end */
if (mpnt->vm_start >= addr+len)
return 0;
/* If we'll make "hole", check the vm areas limit */
if ((mpnt->vm_start < addr && mpnt->vm_end > addr+len)
&& mm->map_count >= max_map_count)
return -ENOMEM;
/*
* We may need one additional vma to fix up the mappings ...
* and this is the last chance for an easy error exit.
*/
extra = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!extra)
return -ENOMEM;
npp = (prev ? &prev->vm_next : &mm->mmap);
free = NULL;
spin_lock(&mm->page_table_lock);
for ( ; mpnt && mpnt->vm_start < addr+len; mpnt = *npp) {
*npp = mpnt->vm_next;
mpnt->vm_next = free;
free = mpnt;
rb_erase(&mpnt->vm_rb, &mm->mm_rb);
}
mm->mmap_cache = NULL; /* Kill the cache. */
spin_unlock(&mm->page_table_lock);
/* Ok - we have the memory areas we should free on the 'free' list,
* so release them, and unmap the page range..
* If the one of the segments is only being partially unmapped,
* it will put new vm_area_struct(s) into the address space.
* In that case we have to be careful with VM_DENYWRITE.
*/
while ((mpnt = free) != NULL) {
unsigned long st, end, size;
struct file *file = NULL;
free = free->vm_next;
st = addr < mpnt->vm_start ? mpnt->vm_start : addr;
end = addr+len;
end = end > mpnt->vm_end ? mpnt->vm_end : end;
size = end - st;
if (mpnt->vm_flags & VM_DENYWRITE &&
(st != mpnt->vm_start || end != mpnt->vm_end) &&
(file = mpnt->vm_file) != NULL) {
atomic_dec(&file->f_dentry->d_inode->i_writecount);
}
remove_shared_vm_struct(mpnt);
mm->map_count--;
zap_page_range(mm, st, size);
/*
* Fix the mapping, and free the old area if it wasn't reused.
*/
extra = unmap_fixup(mm, mpnt, st, size, extra);
if (file)
atomic_inc(&file->f_dentry->d_inode->i_writecount);
}
validate_mm(mm);
/* Release the extra vma struct if it wasn't used */
if (extra)
kmem_cache_free(vm_area_cachep, extra);
free_pgtables(mm, prev, addr, addr+len);
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;
}
/*
* 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;
rb_node_t ** rb_link, * rb_parent;
len = PAGE_ALIGN(len);
if (!len)
return addr;
/*
* 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 (!vm_enough_memory(len >> PAGE_SHIFT))
return -ENOMEM;
flags = VM_DATA_DEFAULT_FLAGS | mm->def_flags;
/* Can we just expand an old anonymous mapping? */
if (rb_parent && vma_merge(mm, prev, rb_parent, addr, addr + len, flags))
goto out;
/*
* create a vma struct for an anonymous mapping
*/
vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!vma)
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;
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;
}
/* Build the RB tree corresponding to the VMA list. */
void build_mmap_rb(struct mm_struct * mm)
{
struct vm_area_struct * vma;
rb_node_t ** rb_link, * rb_parent;
mm->mm_rb = RB_ROOT;
rb_link = &mm->mm_rb.rb_node;
rb_parent = NULL;
for (vma = mm->mmap; vma; vma = vma->vm_next) {
__vma_link_rb(mm, vma, rb_link, rb_parent);
rb_parent = &vma->vm_rb;
rb_link = &rb_parent->rb_right;
}
}
/* Release all mmaps. */
void exit_mmap(struct mm_struct * mm)
{
struct vm_area_struct * mpnt;
release_segments(mm);
spin_lock(&mm->page_table_lock);
mpnt = mm->mmap;
mm->mmap = mm->mmap_cache = NULL;
mm->mm_rb = RB_ROOT;
mm->rss = 0;
spin_unlock(&mm->page_table_lock);
mm->total_vm = 0;
mm->locked_vm = 0;
flush_cache_mm(mm);
while (mpnt) {
struct vm_area_struct * next = mpnt->vm_next;
unsigned long start = mpnt->vm_start;
unsigned long end = mpnt->vm_end;
unsigned long size = end - start;
if (mpnt->vm_ops) {
if (mpnt->vm_ops->close)
mpnt->vm_ops->close(mpnt);
}
mm->map_count--;
remove_shared_vm_struct(mpnt);
zap_page_range(mm, start, size);
if (mpnt->vm_file)
fput(mpnt->vm_file);
kmem_cache_free(vm_area_cachep, mpnt);
mpnt = next;
}
/* This is just debugging */
if (mm->map_count)
BUG();
clear_page_tables(mm, FIRST_USER_PGD_NR, USER_PTRS_PER_PGD);
flush_tlb_mm(mm);
}
/* Insert vm structure into process list sorted by address
* and into the inode's i_mmap ring. If vm_file is non-NULL
* then the i_shared_lock must be held here.
*/
void __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
{
struct vm_area_struct * __vma, * prev;
rb_node_t ** 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);
mm->map_count++;
validate_mm(mm);
}
void insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
{
struct vm_area_struct * __vma, * prev;
rb_node_t ** 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);
}