Re: [PATCH 03/16] x86/boot: Set cr0 to known state in trampoline
From: Andrew Cooper
Date: Wed Oct 19 2022 - 03:44:44 EST
On 06/09/2022 11:41, Evgeniy Baskov wrote:
> diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
> index d33f060900d2..5273367283b7 100644
> --- a/arch/x86/boot/compressed/head_64.S
> +++ b/arch/x86/boot/compressed/head_64.S
> @@ -619,9 +619,8 @@ SYM_CODE_START(trampoline_32bit_src)
> /* Set up new stack */
> leal TRAMPOLINE_32BIT_STACK_END(%ecx), %esp
>
> - /* Disable paging */
> - movl %cr0, %eax
> - btrl $X86_CR0_PG_BIT, %eax
> + /* Disable paging and setup CR0 */
> + movl $(CR0_STATE & ~X86_CR0_PG), %eax
Why here? WP is ignored when PG is disabled.
~Andrew