blob: 05e722af2ec73bdec6066859ee8f9e84bcf992c9 [file] [log] [blame]
/*
* linux/mm/mprotect.c
*
* (C) Copyright 1994 Linus Torvalds
*/
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
static inline void change_pte_range(pmd_t * pmd, unsigned long address,
unsigned long size, pgprot_t newprot)
{
pte_t * pte;
unsigned long end;
if (pmd_none(*pmd))
return;
if (pmd_bad(*pmd)) {
pmd_ERROR(*pmd);
pmd_clear(pmd);
return;
}
pte = pte_offset(pmd, address);
address &= ~PMD_MASK;
end = address + size;
if (end > PMD_SIZE)
end = PMD_SIZE;
do {
if (pte_present(*pte)) {
pte_t entry;
/* Avoid an SMP race with hardware updated dirty/clean
* bits by wiping the pte and then setting the new pte
* into place.
*/
entry = ptep_get_and_clear(pte);
set_pte(pte, pte_modify(entry, newprot));
}
address += PAGE_SIZE;
pte++;
} while (address && (address < end));
}
static inline void change_pmd_range(pgd_t * pgd, unsigned long address,
unsigned long size, pgprot_t newprot)
{
pmd_t * pmd;
unsigned long end;
if (pgd_none(*pgd))
return;
if (pgd_bad(*pgd)) {
pgd_ERROR(*pgd);
pgd_clear(pgd);
return;
}
pmd = pmd_offset(pgd, address);
address &= ~PGDIR_MASK;
end = address + size;
if (end > PGDIR_SIZE)
end = PGDIR_SIZE;
do {
change_pte_range(pmd, address, end - address, newprot);
address = (address + PMD_SIZE) & PMD_MASK;
pmd++;
} while (address && (address < end));
}
static void change_protection(unsigned long start, unsigned long end, pgprot_t newprot)
{
pgd_t *dir;
unsigned long beg = start;
dir = pgd_offset(current->mm, start);
flush_cache_range(current->mm, beg, end);
if (start >= end)
BUG();
spin_lock(&current->mm->page_table_lock);
do {
change_pmd_range(dir, start, end - start, newprot);
start = (start + PGDIR_SIZE) & PGDIR_MASK;
dir++;
} while (start && (start < end));
spin_unlock(&current->mm->page_table_lock);
flush_tlb_range(current->mm, beg, end);
return;
}
static inline int mprotect_fixup_all(struct vm_area_struct * vma, struct vm_area_struct ** pprev,
int newflags, pgprot_t prot)
{
struct vm_area_struct * prev = *pprev;
struct mm_struct * mm = vma->vm_mm;
if (prev && prev->vm_end == vma->vm_start && can_vma_merge(prev, newflags) &&
!vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
spin_lock(&mm->page_table_lock);
prev->vm_end = vma->vm_end;
__vma_unlink(mm, vma, prev);
spin_unlock(&mm->page_table_lock);
kmem_cache_free(vm_area_cachep, vma);
mm->map_count--;
return 0;
}
spin_lock(&mm->page_table_lock);
vma->vm_flags = newflags;
vma->vm_page_prot = prot;
spin_unlock(&mm->page_table_lock);
*pprev = vma;
return 0;
}
static inline int mprotect_fixup_start(struct vm_area_struct * vma, struct vm_area_struct ** pprev,
unsigned long end,
int newflags, pgprot_t prot)
{
struct vm_area_struct * n, * prev = *pprev;
*pprev = vma;
if (prev && prev->vm_end == vma->vm_start && can_vma_merge(prev, newflags) &&
!vma->vm_file && !(vma->vm_flags & VM_SHARED)) {
spin_lock(&vma->vm_mm->page_table_lock);
prev->vm_end = end;
vma->vm_start = end;
spin_unlock(&vma->vm_mm->page_table_lock);
return 0;
}
n = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!n)
return -ENOMEM;
*n = *vma;
n->vm_end = end;
n->vm_flags = newflags;
n->vm_raend = 0;
n->vm_page_prot = prot;
if (n->vm_file)
get_file(n->vm_file);
if (n->vm_ops && n->vm_ops->open)
n->vm_ops->open(n);
vma->vm_pgoff += (end - vma->vm_start) >> PAGE_SHIFT;
lock_vma_mappings(vma);
spin_lock(&vma->vm_mm->page_table_lock);
vma->vm_start = end;
__insert_vm_struct(current->mm, n);
spin_unlock(&vma->vm_mm->page_table_lock);
unlock_vma_mappings(vma);
return 0;
}
static inline int mprotect_fixup_end(struct vm_area_struct * vma, struct vm_area_struct ** pprev,
unsigned long start,
int newflags, pgprot_t prot)
{
struct vm_area_struct * n;
n = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
if (!n)
return -ENOMEM;
*n = *vma;
n->vm_start = start;
n->vm_pgoff += (n->vm_start - vma->vm_start) >> PAGE_SHIFT;
n->vm_flags = newflags;
n->vm_raend = 0;
n->vm_page_prot = prot;
if (n->vm_file)
get_file(n->vm_file);
if (n->vm_ops && n->vm_ops->open)
n->vm_ops->open(n);
lock_vma_mappings(vma);
spin_lock(&vma->vm_mm->page_table_lock);
vma->vm_end = start;
__insert_vm_struct(current->mm, n);
spin_unlock(&vma->vm_mm->page_table_lock);
unlock_vma_mappings(vma);
*pprev = n;
return 0;
}
static inline int mprotect_fixup_middle(struct vm_area_struct * vma, struct vm_area_struct ** pprev,
unsigned long start, unsigned long end,
int newflags, pgprot_t prot)
{
struct vm_area_struct * left, * right;
left = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!left)
return -ENOMEM;
right = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!right) {
kmem_cache_free(vm_area_cachep, left);
return -ENOMEM;
}
*left = *vma;
*right = *vma;
left->vm_end = start;
right->vm_start = end;
right->vm_pgoff += (right->vm_start - left->vm_start) >> PAGE_SHIFT;
left->vm_raend = 0;
right->vm_raend = 0;
if (vma->vm_file)
atomic_add(2,&vma->vm_file->f_count);
if (vma->vm_ops && vma->vm_ops->open) {
vma->vm_ops->open(left);
vma->vm_ops->open(right);
}
vma->vm_pgoff += (start - vma->vm_start) >> PAGE_SHIFT;
vma->vm_raend = 0;
vma->vm_page_prot = prot;
lock_vma_mappings(vma);
spin_lock(&vma->vm_mm->page_table_lock);
vma->vm_start = start;
vma->vm_end = end;
vma->vm_flags = newflags;
__insert_vm_struct(current->mm, left);
__insert_vm_struct(current->mm, right);
spin_unlock(&vma->vm_mm->page_table_lock);
unlock_vma_mappings(vma);
*pprev = right;
return 0;
}
static int mprotect_fixup(struct vm_area_struct * vma, struct vm_area_struct ** pprev,
unsigned long start, unsigned long end, unsigned int newflags)
{
pgprot_t newprot;
int error;
if (newflags == vma->vm_flags) {
*pprev = vma;
return 0;
}
newprot = protection_map[newflags & 0xf];
if (start == vma->vm_start) {
if (end == vma->vm_end)
error = mprotect_fixup_all(vma, pprev, newflags, newprot);
else
error = mprotect_fixup_start(vma, pprev, end, newflags, newprot);
} else if (end == vma->vm_end)
error = mprotect_fixup_end(vma, pprev, start, newflags, newprot);
else
error = mprotect_fixup_middle(vma, pprev, start, end, newflags, newprot);
if (error)
return error;
change_protection(start, end, newprot);
return 0;
}
long do_mprotect(struct mm_struct *mm, unsigned long start, size_t len,
unsigned long prot)
{
unsigned long nstart, end, tmp;
struct vm_area_struct * vma, * next, * prev;
int error = -EINVAL;
if (start & ~PAGE_MASK)
return -EINVAL;
len = PAGE_ALIGN(len);
end = start + len;
if (end < start)
return -ENOMEM;
if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
return -EINVAL;
if (end == start)
return 0;
down_write(&mm->mmap_sem);
vma = find_vma_prev(mm, start, &prev);
error = -ENOMEM;
if (!vma || vma->vm_start > start)
goto out;
for (nstart = start ; ; ) {
unsigned int newflags;
int last = 0;
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
newflags = prot | (vma->vm_flags & ~(PROT_READ | PROT_WRITE | PROT_EXEC));
if ((newflags & ~(newflags >> 4)) & 0xf) {
error = -EACCES;
goto out;
}
if (vma->vm_end > end) {
error = mprotect_fixup(vma, &prev, nstart, end, newflags);
goto out;
}
if (vma->vm_end == end)
last = 1;
tmp = vma->vm_end;
next = vma->vm_next;
error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
if (error)
goto out;
if (last)
break;
nstart = tmp;
vma = next;
if (!vma || vma->vm_start != nstart) {
error = -ENOMEM;
goto out;
}
}
if (next && prev->vm_end == next->vm_start && can_vma_merge(next, prev->vm_flags) &&
!prev->vm_file && !(prev->vm_flags & VM_SHARED)) {
spin_lock(&prev->vm_mm->page_table_lock);
prev->vm_end = next->vm_end;
__vma_unlink(prev->vm_mm, next, prev);
spin_unlock(&prev->vm_mm->page_table_lock);
kmem_cache_free(vm_area_cachep, next);
prev->vm_mm->map_count--;
}
out:
up_write(&mm->mmap_sem);
return error;
}
asmlinkage long sys_mprotect(unsigned long start, size_t len, unsigned long prot)
{
return(do_mprotect(current->mm, start, len, prot));
}