xen: check EFER for NX before setting up GDT mapping

x86-64 assumes NX is available by default, so we need to
explicitly check for it before using NX.  Some first-generation
Intel x86-64 processors didn't support NX, and even recent systems
allow it to be disabled in BIOS.

[ Impact: prevent Xen crash on NX-less 64-bit machines ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stable Kernel <stable@kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 9b5a9f59a478..dd313d035de7 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -4,6 +4,7 @@ obj-y	:=  init.o init_$(BITS).o fault.o ioremap.o extable.o pageattr.o mmap.o \
 # Make sure __phys_addr has no stackprotector
 nostackp := $(call cc-option, -fno-stack-protector)
 CFLAGS_physaddr.o               := $(nostackp)
+CFLAGS_init.o                   := $(nostackp)
 
 obj-$(CONFIG_SMP)               += tlb.o