diff mbox series

[v3,03/24] x86/boot: Set cr0 to known state in trampoline

Message ID 6aada664ff70ec913faae672bb3c16db14b36049.1668958803.git.baskov@ispras.ru (mailing list archive)
State Superseded
Headers show
Series x86_64: Improvements at compressed kernel stage | expand

Commit Message

Evgeniy Baskov Nov. 22, 2022, 11:12 a.m. UTC 
Ensure WP bit to be set to prevent boot code from writing to
non-writable memory pages.

Tested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
---
 arch/x86/boot/compressed/head_64.S | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index d33f060900d2..2a4372b84fc8 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -684,9 +684,8 @@  SYM_CODE_START(trampoline_32bit_src)
 	pushl	$__KERNEL_CS
 	pushl	%eax
 
-	/* Enable paging again. */
-	movl	%cr0, %eax
-	btsl	$X86_CR0_PG_BIT, %eax
+	/* Enable paging and set CR0 to known state (this also sets WP flag) */
+	movl	$CR0_STATE, %eax
 	movl	%eax, %cr0
 
 	lret