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

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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
This commit is contained in:
Joerg Roedel 2020-09-07 15:15:31 +02:00 committed by Borislav Petkov
parent 866b556efa
commit e04b883363
1 changed files with 8 additions and 8 deletions
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16
arch/x86/kernel/head_64.S
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@ -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