Messages in this thread | | | Date | Wed, 2 Mar 2016 20:50:53 +0100 | From | Borislav Petkov <> | Subject | Re: [RFC PATCH] x86: Make sure verify_cpu has a good stack |
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On Wed, Mar 02, 2016 at 10:39:05AM -0800, H. Peter Anvin wrote: > Well, we definitely should use %rip-relative addressing if we can.
Right you are.
> However, even so I believe this breaks if the kernel is loaded anywhere > but its default load address. I think we need to do something like: > > movq stack_start(%rip), %rax > leaq __START_KERNEL_map(%rip), %rdx > subq %rdx, %rax > movq %rax, %rsp > > The use of temporary registers avoids clobbering a valid stack pointer > for even a single instruction if we are given one.
Yeah, we should be prudent and make this as sturdy as possible. I did this:
CONFIG_PHYSICAL_START=0x100beef
and it aligned startup_64 up to ffffffff82000000. It seems to boot fine in kvm. But better safe than sorry.
Thanks.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
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