[PATCH] powerpc vdso updates

This patch cleans up some locking & error handling in the ppc vdso and
moves the vdso base pointer from the thread struct to the mm context
where it more logically belongs. It brings the powerpc implementation
closer to Ingo's new x86 one and also adds an arch_vma_name() function
allowing to print [vsdo] in /proc/<pid>/maps if Ingo's x86 vdso patch is
also applied.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/page.h b/include/asm-powerpc/page.h
index ae610b6..a315d0c 100644
--- a/include/asm-powerpc/page.h
+++ b/include/asm-powerpc/page.h
@@ -192,6 +192,9 @@
 		struct page *p);
 extern int page_is_ram(unsigned long pfn);
 
+struct vm_area_struct;
+extern const char *arch_vma_name(struct vm_area_struct *vma);
+
 #include <asm-generic/memory_model.h>
 #endif /* __ASSEMBLY__ */