Re: [v6 PATCH 08/21] x86/insn-eval: Add utility function to get segment descriptor base address

Ricardo Neri
2017-04-26T22:52:41Z

On Thu, 2017-04-20 at 10:25 +0200, Borislav Petkov wrote:
> > + * insn_get_seg_base() - Obtain base address contained in
> descriptor
> > + * @regs: Set of registers containing the segment selector
> > + * @insn: Instruction structure with selector override prefixes
> > + * @regoff: Operand offset, in pt_regs, of which the selector is
> needed
> > + * @use_default_seg: Use the default segment instead of prefix
> overrides
>
> I'm wondering whether you really need that bool or you can deduce this
> from pt_regs... I guess I'll see...

Probably insn_get_seg_base() itself can verify if there are segment
override prefixes in the struct insn. If yes, use them except for
specific cases such as CS.

On an unrelated note, I still have the problem of using DS vs ES for
string instructions. Perhaps instead of a use_default_seg flag, a
string_instruction flag that indicates how to determine the default
segment.

Thanks and BR,
Ricardo