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Subject[PATCH v5 03/27] x86/boot: Set cr0 to known state in trampoline
Date
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 --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 03c4328a88cb..01fa42d31648 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -660,9 +660,8 @@ 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
--
2.39.2
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