[PATCH] x86-64: Assembly safe page.h and pgtable.h

This patch makes pgtable.h and page.h safe to include
in assembly files like head.S.  Allowing us to use
symbolic constants instead of hard coded numbers when
refering to the page tables.

This patch copies asm-sparc64/const.h to asm-x86_64 to
get a definition of _AC() a very convinient macro that
allows us to force the type when we are compiling the
code in C and to drop all of the type information when
we are using the constant in assembly.  Previously this
was done with multiple definition of the same constant.
const.h was modified slightly so that it works when given
CONFIG options as arguments.

This patch adds #ifndef __ASSEMBLY__ ... #endif
and _AC(1,UL) where appropriate so the assembler won't
choke on the header files.  Otherwise nothing
should have changed.

AK: added const.h to exported headers to fix headers_check

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/asm-x86_64/const.h b/include/asm-x86_64/const.h
new file mode 100644
index 000000000000..54fb08f3db9b
--- /dev/null
+++ b/include/asm-x86_64/const.h
@@ -0,0 +1,20 @@
+/* const.h: Macros for dealing with constants.  */
+
+#ifndef _X86_64_CONST_H
+#define _X86_64_CONST_H
+
+/* Some constant macros are used in both assembler and
+ * C code.  Therefore we cannot annotate them always with
+ * 'UL' and other type specificers unilaterally.  We
+ * use the following macros to deal with this.
+ */
+
+#ifdef __ASSEMBLY__
+#define _AC(X,Y)        X
+#else
+#define __AC(X,Y)       (X##Y)
+#define _AC(X,Y)        __AC(X,Y)
+#endif
+
+
+#endif /* !(_X86_64_CONST_H) */