From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-pci-owner@vger.kernel.org>
Received: from cantor2.suse.de ([195.135.220.15]:47586 "EHLO mx2.suse.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751182AbbCAUat (ORCPT <rfc822;linux-pci@vger.kernel.org>);
	Sun, 1 Mar 2015 15:30:49 -0500
Date: Sun, 1 Mar 2015 21:29:38 +0100
From: Borislav Petkov <bp@suse.de>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>, Jiri Kosina <jkosina@suse.cz>,
	Kees Cook <keescook@chromium.org>,
	Matt Fleming <matt.fleming@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: [PATCH 1/8] x86, kaslr: get kaslr_enabled back correctly
Message-ID: <20150301202938.GD7748@pd.tnic>
References: <1425176259-30087-1-git-send-email-yinghai@kernel.org>
 <1425176259-30087-2-git-send-email-yinghai@kernel.org>
 <CAE9FiQXE5YnSQAkkAxob38Qe+aHZ=niAXL6uLF5650KQPfjPPw@mail.gmail.com>
 <20150301094557.GA7748@pd.tnic>
 <20150301152351.GA17391@gmail.com>
 <CAE9FiQV7DouV+76mzH0jFjFJOFBm-ZmgKpYVjTGAmKao0y3HbA@mail.gmail.com>
 <20150301194904.GC7748@pd.tnic>
 <CAE9FiQVpWQ1NU5Euy2G4btS=94qKCZZ7T0YFsCR1x6iv4C1hjA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
In-Reply-To: <CAE9FiQVpWQ1NU5Euy2G4btS=94qKCZZ7T0YFsCR1x6iv4C1hjA@mail.gmail.com>
Sender: linux-pci-owner@vger.kernel.org
List-ID: <linux-pci.vger.kernel.org>

On Sun, Mar 01, 2015 at 12:24:08PM -0800, Yinghai Lu wrote:
> static allocation in misc.c can not be used to kernel/head_64.S stage safely.

Correct. One possibility that works is sticking it right below
LOAD_PHYSICAL_ADDR:

+static void add_kaslr_setup_data(struct boot_params *params,
+				 u8 *output, __u8 enabled)
 {
+	/*
+	 * Stick it right under LOAD_PHYSICAL_ADDR
+	 */
+	ksd = (struct setup_data *)(output - 2 * sizeof(struct setup_data));

output is LOAD_PHYSICAL_ADDR AFAICT and is the minimum kASLR considers
so right below it should work:

https://lkml.kernel.org/r/20150228105049.GA11038@pd.tnic

-- 
Regards/Gruss,
    Boris.

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