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Message-Id: <20060831213535.29363.10894.stgit@warthog.cambridge.redhat.com>
Date: Thu, 31 Aug 2006 22:35:35 +0100
From: David Howells <dhowells@...hat.com>
To: torvalds@...l.org, akpm@...l.org
Cc: linux-kernel@...r.kernel.org, uclinux-dev@...inux.org,
dhowells@...hat.com
Subject: [PATCH 2/4] NOMMU: Order the per-mm_struct VMA list
From: David Howells <dhowells@...hat.com>
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@...hat.com>
---
mm/nommu.c | 105 ++++++++++++++++++++++++++++++++++++++++++------------------
1 files changed, 73 insertions(+), 32 deletions(-)
diff --git a/mm/nommu.c b/mm/nommu.c
index 9d57c2a..20da741 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -286,6 +286,49 @@ static void show_process_blocks(void)
}
#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;
@@ -305,6 +348,9 @@ static inline struct vm_area_struct *fin
return NULL;
}
+/*
+ * add a VMA in the global tree
+ */
static void add_nommu_vma(struct vm_area_struct *vma)
{
struct vm_area_struct *pvma;
@@ -351,6 +397,9 @@ static void add_nommu_vma(struct vm_area
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;
@@ -828,8 +877,7 @@ unsigned long do_mmap_pgoff(struct file
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);
@@ -908,6 +956,11 @@ static void put_vma(struct vm_area_struc
}
}
+/*
+ * 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;
@@ -917,10 +970,13 @@ #ifdef DEBUG
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);
@@ -946,7 +1002,20 @@ #endif
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;
@@ -973,17 +1042,6 @@ #endif
}
}
-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;
@@ -1037,23 +1095,6 @@ unsigned long do_mremap(unsigned long ad
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)
{
-
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