[IA64] Kexec: define EFI offsets for identity mapping

This is used by paches that move the EFI runtime regions into what is
normally guest space.  A description of why this mapping is made is
included in the patch that makes the mapping.

Cc: Tristan Gingold <tgingold@free.fr>
Cc: Isaku Yamahata <yamahata@valinux.co.jp>
Cc: Alex Williamson <alex.williamson@hp.com>
Cc: Aron Griffis <aron@hp.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

---
Sat, 8 Sep 2007 06:06:30 +0200

Tristan Gingold has rasied the point that mapping EFI memory as
facilitated by this and subsequent patches may cause a security
problem, allowing VTI domains to access memory that they shouldn't.
This needs further analysis.

Index: xen-unstable.hg/xen/include/asm-ia64/xensystem.h
===================================================================
--- xen-unstable.hg.orig/xen/include/asm-ia64/xensystem.h	2008-02-05 16:18:40.000000000 +0900
+++ xen-unstable.hg/xen/include/asm-ia64/xensystem.h	2008-02-05 16:18:58.000000000 +0900
@@ -33,6 +33,12 @@
 #define KERNEL_START		 0xf400000004000000
 #define GATE_ADDR		 KERNEL_START
 
+/* In order for Kexec between Xen and Linux to work EFI needs
+ * to be mapped into the same place by both. It seems most convenient
+ * to make Xen do the dirty work here */
+#define __IA64_EFI_UNCACHED_OFFSET	0xc000000000000000UL
+#define __IA64_EFI_CACHED_OFFSET	0xe000000000000000UL
+
 #define IS_VMM_ADDRESS(addr) ((((addr) >> 60) ^ ((addr) >> 59)) & 1)
 
 #endif // _ASM_IA64_XENSYSTEM_H