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Date: Wed, 19 Oct 2022 07:44:32 +0000 From: Andrew Cooper <Andrew.Cooper3@...rix.com> To: Evgeniy Baskov <baskov@...ras.ru>, Ard Biesheuvel <ardb@...nel.org> CC: Borislav Petkov <bp@...en8.de>, Andy Lutomirski <luto@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, Alexey Khoroshilov <khoroshilov@...ras.ru>, "lvc-project@...uxtesting.org" <lvc-project@...uxtesting.org>, "x86@...nel.org" <x86@...nel.org>, "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>, Andrew Cooper <Andrew.Cooper3@...rix.com> Subject: Re: [PATCH 03/16] x86/boot: Set cr0 to known state in trampoline 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
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