From: Joerg Roedel <jroedel@suse.de>
Date: Mon, 7 Sep 2020 15:15:31 +0200
Subject: x86/head/64: Load GDT after switch to virtual addresses
Git-commit: e04b88336360e101329add0c05e5cb1cebae64fd
Patch-mainline: v5.10-rc1
References: jsc#SLE-14337
Load the GDT right after switching to virtual addresses to make sure
there is a defined GDT for exception handling.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-31-joro@8bytes.org
---
arch/x86/kernel/head_64.S | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -156,6 +156,14 @@ ENTRY(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
@@ -183,14 +191,6 @@ ENTRY(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