Date: Thu, 23 Apr 2015 23:46:16 +0200
From: Borislav Petkov <bp@alien8.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Brian Gerst <brgerst@gmail.com>, Denys Vlasenko <dvlasenk@redhat.com>,
        Ingo Molnar <mingo@kernel.org>, Steven Rostedt <rostedt@goodmis.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>,
        the arch/x86 maintainers <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/asm/entry/32: Restore %ss before SYSRETL if necessary
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On Thu, Apr 23, 2015 at 02:37:27PM -0700, H. Peter Anvin wrote:
> Yes, the NULL SS is a special thing in 64-bit mode. I agree that
> context-switching it is probably the way to go; it should be cheap
> enough. We might even be able to conditionalize it on an X86_BUG_
> flag.

Oh sure, I was thinking of an AMD-specific

	"call amd_fixup_ss"

which gets NOPped out on Intel.

We do those for breakfast :-)

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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