From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: Compat 32-bit syscall entry from 64-bit task!?
Date: Thu, 19 Jan 2012 11:41:03 -0800
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On Thu, Jan 19, 2012 at 11:37 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I would suggest looking at 'rip/rsp' first, though, and just say that
> if it's >32-bit, it's flat mode. Only if both rsp and rip fit in 32
> bits should you even bother start guessing.

Oh, there's a few other hints you can look at. If 'ds' is zero, you
might technically be in 32-bit mode, but realistically nothing really
would work, so you might as well assume you're in long mode.

So you can have a lot of heuristics (including just looking at what
the disassembly itself looks like) if you really want to..

                    Linus