NOMMU: implement access_remote_vm

Recent vm changes brought in a new function which the core procfs code
utilizes.  So implement it for nommu systems too to avoid link failures.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simon Horman <horms@verge.net.au>
Tested-by: Ithamar Adema <ithamar.adema@team-embedded.nl>
Acked-by: Greg Ungerer <gerg@uclinux.org>

1 files changed, 39 insertions, 13 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index cb86e7d5e7f5..c4c542c736a9 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1971,21 +1971,10 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 }
 EXPORT_SYMBOL(filemap_fault);
 
-/*
- * Access another process' address space.
- * - source/target buffer must be kernel space
- */
-int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
+                unsigned long addr, void *buf, int len, int write)
 {
         struct vm_area_struct *vma;
-        struct mm_struct *mm;
-
-        if (addr + len < addr)
-                return 0;
-
-        mm = get_task_mm(tsk);
-        if (!mm)
-                return 0;
 
         down_read(&mm->mmap_sem);
 
@@ -2010,6 +1999,43 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
         }
 
         up_read(&mm->mmap_sem);
+
+        return len;
+}
+
+/**
+ * @access_remote_vm - access another process' address space
+ * @mm:         the mm_struct of the target address space
+ * @addr:       start address to access
+ * @buf:        source or destination buffer
+ * @len:        number of bytes to transfer
+ * @write:      whether the access is a write
+ *
+ * The caller must hold a reference on @mm.
+ */
+int access_remote_vm(struct mm_struct *mm, unsigned long addr,
+                void *buf, int len, int write)
+{
+        return __access_remote_vm(NULL, mm, addr, buf, len, write);
+}
+
+/*
+ * Access another process' address space.
+ * - source/target buffer must be kernel space
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+{
+        struct mm_struct *mm;
+
+        if (addr + len < addr)
+                return 0;
+
+        mm = get_task_mm(tsk);
+        if (!mm)
+                return 0;
+
+        len = __access_remote_vm(tsk, mm, addr, buf, len, write);
+
         mmput(mm);
         return len;
 }