Messages in this thread | | | Date | Wed, 5 Apr 2023 19:54:41 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v5 03/27] x86/boot: Set cr0 to known state in trampoline |
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On Tue, Mar 14, 2023 at 01:13:30PM +0300, Evgeniy Baskov wrote: > 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
This sets a lot more than WP. Why?
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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