From mboxrd@z Thu Jan  1 00:00:00 1970
From: Borislav Petkov <bp@suse.de>
Subject: Re: [v6 PATCH 08/21] x86/insn-eval: Add utility function to get
 segment descriptor base address
Date: Fri, 5 May 2017 19:28:47 +0200
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To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Andrew Morton <akpm@linux-foundation.org>, Brian Gerst <brgerst@gmail.com>, Chris Metcalf <cmetcalf@mellanox.com>, Dave Hansen <dave.hansen@linux.intel.com>, Paolo Bonzini <pbonzini@redhat.com>, Masami Hiramatsu <mhiramat@kernel.org>, Huang Rui <ray.huang@amd.com>, Jiri Slaby <jslaby@suse.cz>, Jonathan Corbet <corbet@lwn.net>, "Michael S. Tsirkin" <mst@redhat.com>, Paul Gortmaker <paul.gortmaker@windriver.com>, Vlastimil Babka <vbabka@suse.cz>, Chen Yucong <slaoub@gmail.com>, Alexandre Julliard <julliard@winehq.org>, Stas Sergeev <stsp@list.ru>, Fenghua Yu <fenghua.yu>

On Wed, Apr 26, 2017 at 03:52:41PM -0700, Ricardo Neri wrote:
> 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.

... and depending on whether in long mode or not.

> 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.

... or you can look at the insn opcode directly. AFAICT, you need
to check whether the opcode is 0xa4 or 0xa5 and that the insn is a
single-byte opcode, i.e., not from the secondary map escaped with 0xf or
some of the other multi-byte opcode maps.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--