[RFC PATCH] x86/head_64.S: remove redundant check that kernel address is 2M aligned

Path	csiph.com!goblin3!goblin.stu.neva.ru!news.roellig-ltd.de!open-news-network.org!weretis.net!feeder4.news.weretis.net!news.mixmin.net!aioe.org!bofh.it!news.nic.it!robomod
From	Alexander Kuleshov <kuleshovmail@gmail.com>
Newsgroups	linux.kernel
Subject	[RFC PATCH] x86/head_64.S: remove redundant check that kernel address is 2M aligned
Date	Fri, 22 Jan 2016 19:20:01 +0100
Message-ID	<qTOtr-7NF-13@gated-at.bofh.it> (permalink)
X-Original-To	Thomas Gleixner <tglx@linutronix.de>
Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=fbYNKcO7ygWPX+xrcW9qG243Gn/2WzlvstXi7x/11/k=; b=P9LIbM9osoWhZQ0BMxY2BIQ7OMQYbgPrcYzcDC2b0boh5wKGxLBgnYGjpzLykMnsjv p2Fzk49PI8BT4/GYPfGXWdKYI5158jzBT6TXMA5C4mxtN7DvZCtUkpY5QLHrtYaUvCap 7IqHo++fTw771VBwaJXEw+iRF6ILAW+OAXH7bhxBbcgYy0imDAdRebxA1LDl7ILw5n41 8vWkTxnWwK98OIj50cHPJuC4FUBukdU3rCBFE+jbOhtMTnjkLYU0HdvhMUC7ACLi/LJA Zb3imc6hZrt70aHtAS5SqplNIl8qXpQclvrG+M1C+6YUB3p4T+6s55tmXPQhQVry5LYb Ck+w==
X-Google-Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=fbYNKcO7ygWPX+xrcW9qG243Gn/2WzlvstXi7x/11/k=; b=G/ij3Qz5FxonBWawWkZOgq7yBgApPNRUjYMvhhUPUOuVNQTRYPfRXL7SpPEtDet+YK 4uVeXPaueeoFemLE3aGbsjw+qA6tFJB6j8kc6je+uX4AVvR2alAsHYCXlLJWds87fuzk qrRN1vJb/BKB92o4kInX2A13v42NY2Zh5Nob8eFDU4G6/WarworaLeRAE9XqvQHTN2WS hRyfMGFs6F23W0EAL8zebqAwnmkJsNlhRoivHzqp8ZMHz9Cxu3vzH3cxJ6xXGiyjAfdm VwoBfSSQfXNnlvVHvqYwETnzhNSmi3scrpSBviWKtvIUS4FSSW3TUUMJQx5xD9cuC/8e L4eA==
X-Gm-Message-State	AG10YOTnH2c68Fx0/E3Nl+2KdP4EKXuBD94yeDr2vhwHNkaUOK2yuOa9rbqweg1XaU6pRQ==
X-Received	by 10.25.136.214 with SMTP id k205mr1471355lfd.39.1453486612319; Fri, 22 Jan 2016 10:16:52 -0800 (PST)
X-Mailer	git-send-email 2.7.0.25.gfc10eb5
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	30
Organization	linux.* mail to news gateway
X-Original-Cc	Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>, Denys Vlasenko <dvlasenk@redhat.com>, Andrey Ryabinin <ryabinin.a.a@gmail.com>, x86@kernel.org, linux-kernel@vger.kernel.org, Alexander Kuleshov <kuleshovmail@gmail.com>
X-Original-Date	Sat, 23 Jan 2016 00:13:12 +0600
X-Original-Message-ID	<1453486392-10289-1-git-send-email-kuleshovmail@gmail.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1315189

Show key headers only | View raw

We check that the base address of the kernel is 2M aligned in
the arch/x86/kernel/head_65.S right after jump to the decompressed
kernel. But we already have a check in the decompress_kernel()
which validates that kernel location is MIN_KERNEL_ALIGN aligned
which is 2M too for x86_64.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 arch/x86/kernel/head_64.S | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index ffdc0e8..4967cba 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -75,12 +75,6 @@ startup_64:
 	leaq	_text(%rip), %rbp
 	subq	$_text - __START_KERNEL_map, %rbp
 
-	/* Is the address not 2M aligned? */
-	movq	%rbp, %rax
-	andl	$~PMD_PAGE_MASK, %eax
-	testl	%eax, %eax
-	jnz	bad_address
-
 	/*
 	 * Is the address too large?
 	 */
-- 
2.7.0.25.gfc10eb5

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[RFC PATCH] x86/head_64.S: remove redundant check that kernel address is 2M aligned Alexander Kuleshov <kuleshovmail@gmail.com> - 2016-01-22 19:20 +0100
  Re: [RFC PATCH] x86/head_64.S: remove redundant check that kernel  address is 2M aligned Brian Gerst <brgerst@gmail.com> - 2016-01-23 02:50 +0100
    Re: [RFC PATCH] x86/head_64.S: remove redundant check that kernel  address is 2M aligned Alexander Kuleshov <kuleshovmail@gmail.com> - 2016-01-23 07:50 +0100

csiph-web