aboutsummaryrefslogtreecommitdiffstats
path: root/mm
diff options
context:
space:
mode:
authorRoland McGrath <roland@redhat.com>2007-02-08 14:20:41 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-09 09:25:47 -0800
commitfa5dc22f8586cc3742413dd05f5cd9e039dfab9e (patch)
tree39a97d91e25794f64e3cc03f1d4a8fa2c8ad78d2 /mm
parent[PATCH] mm: show bounce pages in oom killer output (diff)
downloadlinux-dev-fa5dc22f8586cc3742413dd05f5cd9e039dfab9e.tar.xz
linux-dev-fa5dc22f8586cc3742413dd05f5cd9e039dfab9e.zip
[PATCH] Add install_special_mapping
This patch adds a utility function install_special_mapping, for creating a special vma using a fixed set of preallocated pages as backing, such as for a vDSO. This consolidates some nearly identical code used for vDSO mapping reimplemented for different architectures. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mmap.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index cc3a20819457..eb509ae76553 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2101,3 +2101,75 @@ int may_expand_vm(struct mm_struct *mm, unsigned long npages)
return 0;
return 1;
}
+
+
+static struct page *special_mapping_nopage(struct vm_area_struct *vma,
+ unsigned long address, int *type)
+{
+ struct page **pages;
+
+ BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+
+ address -= vma->vm_start;
+ for (pages = vma->vm_private_data; address > 0 && *pages; ++pages)
+ address -= PAGE_SIZE;
+
+ if (*pages) {
+ struct page *page = *pages;
+ get_page(page);
+ return page;
+ }
+
+ return NOPAGE_SIGBUS;
+}
+
+/*
+ * Having a close hook prevents vma merging regardless of flags.
+ */
+static void special_mapping_close(struct vm_area_struct *vma)
+{
+}
+
+static struct vm_operations_struct special_mapping_vmops = {
+ .close = special_mapping_close,
+ .nopage = special_mapping_nopage,
+};
+
+/*
+ * Called with mm->mmap_sem held for writing.
+ * Insert a new vma covering the given region, with the given flags.
+ * Its pages are supplied by the given array of struct page *.
+ * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
+ * The region past the last page supplied will always produce SIGBUS.
+ * The array pointer and the pages it points to are assumed to stay alive
+ * for as long as this mapping might exist.
+ */
+int install_special_mapping(struct mm_struct *mm,
+ unsigned long addr, unsigned long len,
+ unsigned long vm_flags, struct page **pages)
+{
+ struct vm_area_struct *vma;
+
+ vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (unlikely(vma == NULL))
+ return -ENOMEM;
+
+ vma->vm_mm = mm;
+ vma->vm_start = addr;
+ vma->vm_end = addr + len;
+
+ vma->vm_flags = vm_flags | mm->def_flags;
+ vma->vm_page_prot = protection_map[vma->vm_flags & 7];
+
+ vma->vm_ops = &special_mapping_vmops;
+ vma->vm_private_data = pages;
+
+ if (unlikely(insert_vm_struct(mm, vma))) {
+ kmem_cache_free(vm_area_cachep, vma);
+ return -ENOMEM;
+ }
+
+ mm->total_vm += len >> PAGE_SHIFT;
+
+ return 0;
+}