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Subject: Re: [RFC 1/7] x86/asm/64: Allocate and enable the SYSENTER stack
To: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>
References: <cover.1510371795.git.luto@kernel.org>
 <96d9a6a2849d20775028ea1586a84118ad82670b.1510371795.git.luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Brian Gerst <brgerst@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <ea8f175e-359f-d4b3-cdd2-96650ce15715@intel.com>
Date: Mon, 13 Nov 2017 11:07:33 -0800
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On 11/10/2017 08:05 PM, Andy Lutomirski wrote:
> This will simplify some future code changes that will want some
> temporary stack space in more places.  It also lets us get rid of a
> SWAPGS_UNSAFE_STACK user.
> 
> This does not depend on CONFIG_IA32_EMULATION because we'll want the
> stack space even without IA32 emulation.

It was never clear to me why we don't use this on 64-bit today.  Does
anybody know why?