linux-kernel - linux-next: reservetop fix disables mem=

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Date:	Mon, 24 Aug 2009 17:45:26 +0100 (BST)
From:	Hugh Dickins <hugh.dickins@...cali.co.uk>
To:	Ingo Molnar <mingo@...e.hu>
cc:	Xiao Guangrong <xiaooguangrong@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>, yinghai@...nel.org,
	linux-kernel@...r.kernel.org
Subject: linux-next: reservetop fix disables mem=

I find the "mem=" boot parameter disabled in today's linux-next:
reverting the tip commit below fixes that.

Hugh

From: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
Date: Thu, 20 Aug 2009 12:23:11 +0000 (+0800)
Subject: x86: Fix system crash when loading with "reservetop" parameter
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fmingo%2Flinux-2.6-x86.git;a=commitdiff_plain;h=8126dec32738421afa362114337331337b4be17f

x86: Fix system crash when loading with "reservetop" parameter

The system will die if the kernel is booted with "reservetop"
parameter, in present code, parse "reservetop" parameter after
early_ioremap_init(), and some function still use
early_ioremap() after it.

The problem is, "reservetop" parameter can modify
'FIXADDR_TOP', then the virtual address got by early_ioremap()
is base on old 'FIXADDR_TOP', but the page mapping is base on
new 'FIXADDR_TOP', it will occur page fault, and the IDT is not
prepare yet, so, the system is dead.

So, put parse_early_param() in the front of
early_ioremap_init() in this patch.

Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
Cc: yinghai@...nel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>
LKML-Reference: <4A8D402F.4080805@...fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 63f32d2..02643cc 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -711,6 +711,11 @@ void __init setup_arch(char **cmdline_p)
 	printk(KERN_INFO "Command line: %s\n", boot_command_line);
 #endif
 
+	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
+	*cmdline_p = command_line;
+
+	parse_early_param();
+
 	/* VMI may relocate the fixmap; do this before touching ioremap area */
 	vmi_init();
 
@@ -793,11 +798,6 @@ void __init setup_arch(char **cmdline_p)
 #endif
 #endif
 
-	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
-	*cmdline_p = command_line;
-
-	parse_early_param();
-
 #ifdef CONFIG_X86_64
 	check_efer();
 #endif
--
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