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Diffstat (limited to 'mm/nommu.c')
-rw-r--r--mm/nommu.c63
1 files changed, 46 insertions, 17 deletions
diff --git a/mm/nommu.c b/mm/nommu.c
index 4f87b2f43a2..23cfa8ec914 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -350,6 +350,26 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
EXPORT_SYMBOL(find_vma);
/*
+ * look up the first VMA exactly that exactly matches addr
+ * - should be called with mm->mmap_sem at least held readlocked
+ */
+static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
+ unsigned long addr)
+{
+ struct vm_list_struct *vml;
+
+ /* search the vm_start ordered list */
+ for (vml = mm->context.vmlist; vml; vml = vml->next) {
+ if (vml->vma->vm_start == addr)
+ return vml->vma;
+ if (vml->vma->vm_start > addr)
+ break;
+ }
+
+ return NULL;
+}
+
+/*
* find a VMA in the global tree
*/
static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
@@ -1071,20 +1091,20 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
}
/*
- * Expand (or shrink) an existing mapping, potentially moving it at the
- * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
+ * expand (or shrink) an existing mapping, potentially moving it at the same
+ * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
*
- * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
- * This option implies MREMAP_MAYMOVE.
+ * under NOMMU conditions, we only permit changing a mapping's size, and only
+ * as long as it stays within the hole allocated by the kmalloc() call in
+ * do_mmap_pgoff() and the block is not shareable
*
- * on uClinux, we only permit changing a mapping's size, and only as long as it stays within the
- * hole allocated by the kmalloc() call in do_mmap_pgoff() and the block is not shareable
+ * MREMAP_FIXED is not supported under NOMMU conditions
*/
unsigned long do_mremap(unsigned long addr,
unsigned long old_len, unsigned long new_len,
unsigned long flags, unsigned long new_addr)
{
- struct vm_list_struct *vml = NULL;
+ struct vm_area_struct *vma;
/* insanity checks first */
if (new_len == 0)
@@ -1093,29 +1113,38 @@ unsigned long do_mremap(unsigned long addr,
if (flags & MREMAP_FIXED && new_addr != addr)
return (unsigned long) -EINVAL;
- for (vml = current->mm->context.vmlist; vml; vml = vml->next)
- if (vml->vma->vm_start == addr)
- goto found;
-
- return (unsigned long) -EINVAL;
+ vma = find_vma_exact(current->mm, addr);
+ if (!vma)
+ return (unsigned long) -EINVAL;
- found:
- if (vml->vma->vm_end != vml->vma->vm_start + old_len)
+ if (vma->vm_end != vma->vm_start + old_len)
return (unsigned long) -EFAULT;
- if (vml->vma->vm_flags & VM_MAYSHARE)
+ if (vma->vm_flags & VM_MAYSHARE)
return (unsigned long) -EPERM;
if (new_len > kobjsize((void *) addr))
return (unsigned long) -ENOMEM;
/* all checks complete - do it */
- vml->vma->vm_end = vml->vma->vm_start + new_len;
+ vma->vm_end = vma->vm_start + new_len;
askedalloc -= old_len;
askedalloc += new_len;
- return vml->vma->vm_start;
+ return vma->vm_start;
+}
+
+asmlinkage unsigned long sys_mremap(unsigned long addr,
+ unsigned long old_len, unsigned long new_len,
+ unsigned long flags, unsigned long new_addr)
+{
+ unsigned long ret;
+
+ down_write(&current->mm->mmap_sem);
+ ret = do_mremap(addr, old_len, new_len, flags, new_addr);
+ up_write(&current->mm->mmap_sem);
+ return ret;
}
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,