Messages in this thread Patch in this message | | | From | Evgeniy Baskov <> | Subject | [PATCH 3/8] x86/boot: Set cr0 to known state in trampoline | Date | Mon, 1 Aug 2022 19:39:00 +0300 |
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Ensure WP bit to be set to prevent boot code from writing to non-writable memory pages.
Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
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 movl %eax, %cr0 /* Check what paging mode we want to be in after the trampoline */ -- 2.35.1
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