linux-kernel - Re: [RFC 3/4] x86/signal/64: Re-add support for SS in the 64-bit signal context

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Message-ID: <20151014165736.GT2048@uranus>
Date:	Wed, 14 Oct 2015 19:57:36 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Andy Lutomirski <luto@...nel.org>, Stas Sergeev <stsp@...t.ru>,
	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Pavel Emelyanov <xemul@...allels.com>
Subject: Re: [RFC 3/4] x86/signal/64: Re-add support for SS in the 64-bit
 signal context

On Wed, Oct 14, 2015 at 09:42:58AM -0700, Andy Lutomirski wrote:
> 
> That's the intent.
> 
> If you write __pad = 0, don't set UC_STRICT_RESTORE_SS, and leave cs
> set to a 64-bit value, then the kernel will detect that 0 is not a
> valid SS and will fix it for you.
> 
> If you do write UC_STRICT_RESTORE_SS (e.g. if you saved on a new
> kernel and you restore the saved uc_flags), then you'll get a new
> signal delivered.

Yeah, I just wanna be sure I understood the patch correctly. Thanks!

> If you're restoring a 32-bit or 16-bit context, then none of the above
> applies, but I doubt that CRIU supports that anyway.

True. I didn't implemented compat mode for criu yet, it's in todo.
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