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Subject[tip:x86/urgent] x86: Fix system crash when loading with "reservetop" parameter
Commit-ID:  8126dec32738421afa362114337331337b4be17f
Gitweb: http://git.kernel.org/tip/8126dec32738421afa362114337331337b4be17f
Author: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
AuthorDate: Thu, 20 Aug 2009 20:23:11 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 21 Aug 2009 16:40:30 +0200

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@cn.fujitsu.com>
Cc: yinghai@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4A8D402F.4080805@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
arch/x86/kernel/setup.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)

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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