Messages in this thread | | | Date | Tue, 1 Mar 2022 22:02:45 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 18/39] x86/ibt: Add IBT feature, MSR and #CP handling |
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On Tue, Mar 01, 2022 at 04:14:42PM +0100, Peter Zijlstra wrote:
> Something like so? > > diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S > index 399f075ccdc4..5b65f6ec5ee6 100644 > --- a/arch/x86/kernel/relocate_kernel_64.S > +++ b/arch/x86/kernel/relocate_kernel_64.S > @@ -114,6 +114,14 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) > /* store the start address on the stack */ > pushq %rdx > > + /* > + * Clear X86_CR4_CET (if it was set) such that we can clear CR0_WP > + * below. > + */ > + movq %cr4, %rax > + andq $~(X86_CR4_CET), %rax > + movq %rax, %cr4 > + > /* > * Set cr0 to a known state: > * - Paging enabled
I *think* it worked, I 'apt install kexec-tools' and copied the magic commands Josh gave over IRC and the machine went and came back real quick.
Lacking useful console I can't say much more.
I pushed out a version with these things on.
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