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From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Wed, 21 Jan 2015 14:40:39 +0100
Message-ID: <CAK1hOcMqp8pHVLRPfH9ui1UFvnU1M2bUpdkecdGW-cmSHth9_Q@mail.gmail.com>
Subject: Re: [PATCHv2 1/4] x86_64: cleanup THREAD_INFO(reg,offset) macro
To: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Andy Lutomirski <luto@amacapital.net>, X86 ML <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, Borislav Petkov <bp@suse.de>,
        Rik van Riel <riel@redhat.com>
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On Sun, Jan 18, 2015 at 12:45 PM, Alexander van Heukelum
<heukelum@fastmail.fm> wrote:
> The macro THREAD_INFO(reg,offset) is used in assembly to compute the
> offset between the user ptregs and the thread_info struct. Change
> the macro and all its uses so that offset is given as the current
> top of stack in the pt_regs frame. The generated code is identical.

What is the purpose of doing this?

I don't mean to say that it's pointless, but it is also not obvious
why it's better than the code before patch.