[tip:x86/pat] x86: Fix earlyprintk=dbgp for machines without NX

From: tip-bot for Jan Beulich
Date: Sat Aug 29 2009 - 09:58:38 EST

Commit-ID: 47d25003cbd9e9030a95f7ccc4e70fec6aa7b844
Gitweb: http://git.kernel.org/tip/47d25003cbd9e9030a95f7ccc4e70fec6aa7b844
Author: Jan Beulich <JBeulich@xxxxxxxxxx>
AuthorDate: Fri, 28 Aug 2009 14:11:57 +0100
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sat, 29 Aug 2009 15:47:32 +0200

x86: Fix earlyprintk=dbgp for machines without NX

Since parse_early_param() may (e.g. for earlyprintk=dbgp)
involve calls to page table manipulation functions (here
set_fixmap_nocache()), NX hardware support must be determined
before calling that function (so that __supported_pte_mask gets
properly set up).

But the call after parse_early_param() can also not go away, as
that will honor eventual command line specified disabling of
the NX functionality.

( This will then just result in whatever mappings got
established during parse_early_param() having the NX bit set
despite it being disabled on the command line, but I think
that's tolerable).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
LKML-Reference: <4A97F3BD02000078000121B9@xxxxxxxxxxxxxxxxxx>
[ merged to x86/pat to resolve a conflict. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

arch/x86/kernel/setup.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 02643cc..eb1f1e6 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -714,6 +714,16 @@ void __init setup_arch(char **cmdline_p)
strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
*cmdline_p = command_line;

+#ifdef CONFIG_X86_64
+ /*
+ * Must call this twice: Once just to detect whether hardware doesn't
+ * support NX (so that the early EHCI debug console setup can safely
+ * call set_fixmap(), and then again after parsing early parameters to
+ * honor the respective command line option.
+ */
+ check_efer();

/* VMI may relocate the fixmap; do this before touching ioremap area */
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