[IA64] Kexec: Add identity mapping of EFI memory to dtlb_miss

Cc: Isaku Yamahata <yamahata@valinux.co.jp>
Cc: Tristan Gingold <tgingold@free.fr>
Signed-off-by: Simon Horman <horms@verge.net.au>

--- 
Thu, 06 Dec 2007 16:15:27 +0900
* region register index needs to be bit shifted 61 bits to the left
* Use EFI region detection logic similar to other patches

Thu, 24 Jan 2008 16:02:33 +0900
* Check rr7 not rr6, as the rr changes don't really take
  full affect until rr7 is switched - and checking on rr6 doesn't work
  in alt_dtlb_miss

Index: xen-unstable.hg/xen/arch/ia64/xen/ivt.S
===================================================================
--- xen-unstable.hg.orig/xen/arch/ia64/xen/ivt.S	2008-01-25 13:31:34.000000000 +0900
+++ xen-unstable.hg/xen/arch/ia64/xen/ivt.S	2008-01-25 13:32:22.000000000 +0900
@@ -138,6 +138,24 @@ ENTRY(dtlb_miss)
 	/* If address belongs to VMM, go to alt tlb handler */
 	cmp.eq p6,p0=0x1e,r17
 (p6)	br.cond.spnt	late_alt_dtlb_miss
+
+	// If it is an EFI address then must have XEN_EFI_RID set
+	// And if that is true, go to alt tlb handler
+	// ((r17 == 0x18 || r17 == 0x1c) && rr7 == XEN_EFI_RID)
+	// Note: rr7 == XEN_EFI_RID implies rr6 == XEN_EFI_RID
+	movl r23=7 << 61
+	;;
+	cmp.eq p8,p0=0x18,r17		// 0xc...
+	mov r23=rr[r23]
+	;;
+	cmp.eq.or p8,p0=0x1c,r17	// 0xe...
+	mov r25=XEN_EFI_RID
+	;;
+	cmp.eq.and p8,p0=r25,r23	// rr7 == XEN_EFI_RID
+	;;
+(p8)	br.cond.spnt late_alt_dtlb_miss
+	;;
+
 	br.cond.sptk fast_tlb_miss_reflect
 	;;
 END(dtlb_miss)
