Re: [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0

2017-04-27 Thread Ricardo Neri
On Wed, 2017-04-26 at 10:05 +0200, Borislav Petkov wrote: > On Tue, Apr 25, 2017 at 07:04:20PM -0700, Ricardo Neri wrote: > > For the specific case of ModRM.mod being 0, I feel I need to clarify > > that REX.B is not decoded and if SIB.base is %r13 the base is also 0. > > Well, that all doesn't

Re: [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0

2017-04-26 Thread Borislav Petkov
On Tue, Apr 25, 2017 at 07:04:20PM -0700, Ricardo Neri wrote: > For the specific case of ModRM.mod being 0, I feel I need to clarify > that REX.B is not decoded and if SIB.base is %r13 the base is also 0. Well, that all doesn't matter. The rule is this: ModRM.mod == 00b and ModRM.r/m == 101b ->

Re: [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0

2017-04-25 Thread Ricardo Neri
On Wed, 2017-04-12 at 00:08 +0200, Borislav Petkov wrote: > On Tue, Mar 07, 2017 at 04:32:36PM -0800, Ricardo Neri wrote: > > Section 2.2.1.2 of the Intel 64 and IA-32 Architectures Software > > Developer's Manual volume 2A states that when a SIB byte is used and the > > base of the SIB byte

Re: [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0

2017-04-11 Thread Borislav Petkov
On Tue, Mar 07, 2017 at 04:32:36PM -0800, Ricardo Neri wrote: > Section 2.2.1.2 of the Intel 64 and IA-32 Architectures Software > Developer's Manual volume 2A states that when a SIB byte is used and the > base of the SIB byte points to R/EBP (i.e., base = 5) and the mod part > of the ModRM byte