linux-kernel - Re: [regression] x86/signal/64: Fix SS handling for signals delivered to 64-bit programs breaks dosemu

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Message-ID: <CAMzpN2jbBq-33HVFZ0fHUtzMX-m9V5TUPCSp9VVf2zi=dd=EMw@mail.gmail.com>
Date:	Thu, 13 Aug 2015 13:00:25 -0400
From:	Brian Gerst <brgerst@...il.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Stas Sergeev <stsp@...t.ru>,
	Linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: [regression] x86/signal/64: Fix SS handling for signals delivered
 to 64-bit programs breaks dosemu

On Thu, Aug 13, 2015 at 11:43 AM, Andy Lutomirski <luto@...capital.net> wrote:
> On Thu, Aug 13, 2015 at 8:37 AM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
>> On Tue, Aug 11, 2015 at 5:17 PM, Stas Sergeev <stsp@...t.ru> wrote:
>>>
>>> I realize this patch may be good to have in general, but
>>> breaking userspace without a single warning is a bit
>>> discouraging. Seems like the old "we don't break userspace"
>>> rule have gone.
>>
>> That rule hasn't gone anywhere.
>>
>> Does a plain revert just fix everything? Because if so, that's the
>> right thing to do, and we can just re-visit this later.
>>
>> I don't understand why Andy and Ingo are even discussing this. What
>> the f*ck, guys?
>>
>
> I'm trying to fix it without reverting.  If that doesn't work, then we
> revert.  Yesterday, I thought I had a reasonably clean fix, but it
> turned out that it only solved half of the problem.
>
> If we revert, I think I need to check what will break due to the
> revert.  I need to check at least Wine, and we'll have to do something
> about all the selftests that will start failing.  I also need to check
> CRIU, and IIRC CRIU has started using the new sigcontext SS in new
> versions.

I don't think Wine will be a problem, at least how it is currently set
up.  16-bit support is only in the 32-bit build.  The 64-bit build
only supports Win64 apps, and will call the 32-bit version (installed
in parallel) to run 32 and 16-bit apps.

--
Brian Gerst
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