[PATCH] NOMMU: Order the per-mm_struct VMA list
Order the per-mm_struct VMA list by address so that searching it can be cut
short when the appropriate address has been exceeded.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/nommu.c b/mm/nommu.c
index 829fc90..4f87b2f4 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -310,6 +310,48 @@
}
#endif /* DEBUG */
+/*
+ * add a VMA into a process's mm_struct in the appropriate place in the list
+ * - should be called with mm->mmap_sem held writelocked
+ */
+static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
+{
+ struct vm_list_struct **ppv;
+
+ for (ppv = ¤t->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
+ if ((*ppv)->vma->vm_start > vml->vma->vm_start)
+ break;
+
+ vml->next = *ppv;
+ *ppv = vml;
+}
+
+/*
+ * 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_list_struct *loop, *vml;
+
+ /* search the vm_start ordered list */
+ vml = NULL;
+ for (loop = mm->context.vmlist; loop; loop = loop->next) {
+ if (loop->vma->vm_start > addr)
+ break;
+ vml = loop;
+ }
+
+ if (vml && vml->vma->vm_end > addr)
+ return vml->vma;
+
+ return NULL;
+}
+EXPORT_SYMBOL(find_vma);
+
+/*
+ * find a VMA in the global tree
+ */
static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
{
struct vm_area_struct *vma;
@@ -329,6 +371,9 @@
return NULL;
}
+/*
+ * add a VMA in the global tree
+ */
static void add_nommu_vma(struct vm_area_struct *vma)
{
struct vm_area_struct *pvma;
@@ -375,6 +420,9 @@
rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
}
+/*
+ * delete a VMA from the global list
+ */
static void delete_nommu_vma(struct vm_area_struct *vma)
{
struct address_space *mapping;
@@ -852,8 +900,7 @@
realalloc += kobjsize(vml);
askedalloc += sizeof(*vml);
- vml->next = current->mm->context.vmlist;
- current->mm->context.vmlist = vml;
+ add_vma_to_mm(current->mm, vml);
up_write(&nommu_vma_sem);
@@ -932,6 +979,11 @@
}
}
+/*
+ * release a mapping
+ * - under NOMMU conditions the parameters must match exactly to the mapping to
+ * be removed
+ */
int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
{
struct vm_list_struct *vml, **parent;
@@ -941,10 +993,13 @@
printk("do_munmap:\n");
#endif
- for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next)
+ for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
+ if ((*parent)->vma->vm_start > addr)
+ break;
if ((*parent)->vma->vm_start == addr &&
((len == 0) || ((*parent)->vma->vm_end == end)))
goto found;
+ }
printk("munmap of non-mmaped memory by process %d (%s): %p\n",
current->pid, current->comm, (void *) addr);
@@ -970,7 +1025,20 @@
return 0;
}
-/* Release all mmaps. */
+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;
+}
+
+/*
+ * Release all mappings
+ */
void exit_mmap(struct mm_struct * mm)
{
struct vm_list_struct *tmp;
@@ -997,17 +1065,6 @@
}
}
-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;
-}
-
unsigned long do_brk(unsigned long addr, unsigned long len)
{
return -ENOMEM;
@@ -1061,23 +1118,6 @@
return vml->vma->vm_start;
}
-/*
- * Look up the first VMA which satisfies addr < vm_end, NULL if none
- * - should be called with mm->mmap_sem at least readlocked
- */
-struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
-{
- struct vm_list_struct *vml;
-
- for (vml = mm->context.vmlist; vml; vml = vml->next)
- if (addr >= vml->vma->vm_start && addr < vml->vma->vm_end)
- return vml->vma;
-
- return NULL;
-}
-
-EXPORT_SYMBOL(find_vma);
-
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
unsigned int foll_flags)
{
