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Commit b75fe4e5 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge
Browse files

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: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stable Kernel <stable@kernel.org>
parent 79b520e8

arch/x86/mm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/xen/enlighten.c

+5 −5
Original line number Diff line number Diff line
@@ -1083,6 +1083,11 @@ asmlinkage void __init xen_start_kernel(void) 


	__supported_pte_mask |= _PAGE_IOMAP;



#ifdef CONFIG_X86_64

	/* Work out if we support NX */

	check_efer();

#endif



	xen_setup_features();



	/* Get mfn list */
@@ -1123,11 +1128,6 @@ asmlinkage void __init xen_start_kernel(void) 


	pgd = (pgd_t *)xen_start_info->pt_base;



#ifdef CONFIG_X86_64

	/* Work out if we support NX */

	check_efer();

#endif



	/* Don't do the full vcpu_info placement stuff until we have a

	   possible map and a non-dummy shared_info. */

	per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];