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Message-ID: <1493247161.36058.77.camel@ranerica-desktop>
Subject: Re: [v6 PATCH 08/21] x86/insn-eval: Add utility function to get
 segment descriptor base address
From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Borislav Petkov <bp@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>,
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Date: Wed, 26 Apr 2017 15:52:41 -0700
In-Reply-To: <20170420082533.hwc6eon3aom43qzo@pd.tnic>
References: <20170308003254.27833-1-ricardo.neri-calderon@linux.intel.com>
         <20170308003254.27833-9-ricardo.neri-calderon@linux.intel.com>
         <20170420082533.hwc6eon3aom43qzo@pd.tnic>
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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