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Date: Thu, 13 Aug 2015 17:27:09 -0700
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Subject: Re: [regression] x86/signal/64: Fix SS handling for signals delivered
 to 64-bit programs breaks dosemu
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Stas Sergeev <stsp@list.ru>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Raymond Jennings <shentino@gmail.com>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Pavel Emelyanov <xemul@parallels.com>,
        Linux kernel <linux-kernel@vger.kernel.org>
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On Thu, Aug 13, 2015 at 5:17 PM, Stas Sergeev <stsp@list.ru> wrote:
>
> For example because you can as well do:
> prctl(ARCH_SET_SIGNAL_SS, 0)
> which will mean "restore ss in sighandler to its current value",

I really think a prctl() is the wrong thing to do.

If you want a signal handler to save/restore segments, I think it
should be a SA_xyz flag to sigaction() (the way we have SA_RESTART
etc).  And off by default because of the obvious compatibility issues.

                Linus