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Subject: Re: [PATCH v2 0/4] x86: sigcontext fixes, again
To: Andy Lutomirski <luto@kernel.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
References: <cover.1445822498.git.luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>, Denys Vlasenko <dvlasenk@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>,
        Stas Sergeev <stsp@users.sourceforge.net>
From: Stas Sergeev <stsp@list.ru>
Message-ID: <562E126E.6030300@list.ru>
Date: Mon, 26 Oct 2015 14:45:50 +0300
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26.10.2015 04:25, Andy Lutomirski пишет:
> This is take 2 at fixing x86 64-bit signals wrt SS.  After a lot of
> thought, this is not controlled by any flags -- I would much prefer
> to avoid opt-in behavior.  Instead, it just tries hard to avoid
> triggering the cases that break DOSEMU.
> 
> Stas, this now seems to pass the test you sent me.  It works with
> stock dosemu2 (I haven't tested classic dosemu because I can't get it
> to work regardless).
I'll test it myself then.
But this will have to wait till a week-end I am afraid.
In a mean time you can test vm86() - last time I tried,
I got oops and hard lockup.

> It also works with a patched dosemu2 that bypasses
> the userspace trampoline:
> 
> https://github.com/amluto/dosemu2/commit/571b4d08dc885b7a133e444a2ad23e0d21366206
> 
> With this applied, all of the x86 selftests pass on x86_64.  That
> wasn't the case before -- ldt_gdt_64 was broken.
> 
> This is a bit risky, and another option would be to do nothing at
> all.  Then we'd disable the problematic self-tests (sigh), and
No, another option is a new SA_ flag.