Date: Fri, 3 Jul 2015 08:33:13 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
        X86 ML <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
        Rik van Riel <riel@redhat.com>, Oleg Nesterov <oleg@redhat.com>,
        Denys Vlasenko <vda.linux@googlemail.com>,
        Kees Cook <keescook@chromium.org>, Brian Gerst <brgerst@gmail.com>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH v4 14/17] x86/asm/entry/64: Migrate error and interrupt
 exit work to C
Message-ID: <20150703063313.GA19561@gmail.com>
References: <cover.1435602481.git.luto@kernel.org>
 <1a5858d079609a3e293123c9ee45de433a4e9c44.1435602481.git.luto@kernel.org>
 <20150702120932.GH4001@pd.tnic>
 <CALCETrUhoxySrDCB0+qsGP3qRzkVML7Kp7-PgfcJdg0xzri6MQ@mail.gmail.com>
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* Andy Lutomirski <luto@amacapital.net> wrote:

> If we move even more of this stuff into C, then this problem goes away.  "call 
> enter_from_user_mode" turns into "enter_from_user_mode()" or similar.

Yes. I think we should first see how that process works out, and then see what 
else can be done. For the initial step I'm willing to trade up to 10 cycles in 
exchange for sane and maintainable x86 entry code that we can then speed up ...

I presume we are still within that budget?

Thanks,

	Ingo
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