Messages in this thread | | | Date | Tue, 9 Nov 2010 12:48:57 -0800 | From | Kees Cook <> | Subject | Re: [PATCH 3/4] x86: call verify_cpu during 32bit CPU startup |
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Hi Pekka,
On Tue, Nov 09, 2010 at 10:28:16PM +0200, Pekka Enberg wrote: > So why can't we do patch 2/4 XD_DISABLE clearing in > early_init_intel()?
Because it's too late, unfortunately. I went around a few times about this with Peter Anvin, and ultimately he agreed that it needed to go in verify_cpu() for now.
> Why do we want to call verify_cpu() from > arch/x86/kernel/head_32.S and not from > arch/x86/boot/compressed/head_32.S like we do on 64-bit?
Because the longmode/SSE tests being performed in verify_cpu() need to happen that early for 64bit. Instead of including it in two places for 32bit, we can just include it once in arch/x86/kernel/head_32.S.
-Kees
-- Kees Cook Ubuntu Security Team
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