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Date: Mon, 9 Mar 2015 17:18:59 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, 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>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] x86: save user %rsp in pt_regs->sp on SYSCALL64
 fastpath
Message-ID: <20150309161859.GA22871@gmail.com>
References: <1425847750-23362-1-git-send-email-dvlasenk@redhat.com>
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* Denys Vlasenko <dvlasenk@redhat.com> wrote:

> PER_CPU(old_rsp) usage is simplified - now it is used only
> as temp storage, and userspace stack pointer is immediately stored
> in pt_regs->sp on syscall entry, instead of being used later,
> on syscall exit.
> 
> All references of PER_CPU(old_rsp) in C code are gone -
> pt_regs->sp is used instead.
> 
> This also allows to get rid of thread_struct::usersp,
> which was needed only to set PER_CPU(old_rsp) for
> correct return from fork/clone.

Would it be possible to split this one into two parts as well:

  - Essential changes into the first one (old_rsp update 
    simplification, usersp usage conversion)

  - Removal of usersp, old_rsp extern declaration removal, comment 
    changes, in the second patch?

Thanks,

	Ingo