Commit e04b8833 authored by Joerg Roedel's avatar Joerg Roedel Committed by Borislav Petkov
Browse files

x86/head/64: Load GDT after switch to virtual addresses 



Load the GDT right after switching to virtual addresses to make sure
there is a defined GDT for exception handling.

Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-31-joro@8bytes.org
parent 866b556e

arch/x86/kernel/head_64.S

+8 −8
Original line number Diff line number Diff line
@@ -158,6 +158,14 @@ SYM_CODE_START(secondary_startup_64) 
1:

	UNWIND_HINT_EMPTY



	/*

	 * We must switch to a new descriptor in kernel space for the GDT

	 * because soon the kernel won't have access anymore to the userspace

	 * addresses where we're currently running on. We have to do that here

	 * because in 32bit we couldn't load a 64bit linear address.

	 */

	lgdt	early_gdt_descr(%rip)



	/* Check if nx is implemented */

	movl	$0x80000001, %eax

	cpuid
@@ -185,14 +193,6 @@ SYM_CODE_START(secondary_startup_64) 
	pushq $0

	popfq



	/*

	 * We must switch to a new descriptor in kernel space for the GDT

	 * because soon the kernel won't have access anymore to the userspace

	 * addresses where we're currently running on. We have to do that here

	 * because in 32bit we couldn't load a 64bit linear address.

	 */

	lgdt	early_gdt_descr(%rip)



	/* set up data segments */

	xorl %eax,%eax

	movl %eax,%ds

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