x86, mm: Report state of NX protections during boot

It is possible for x86_64 systems to lack the NX bit either due to the
hardware lacking support or the BIOS having turned off the CPU capability,
so NX status should be reported.  Additionally, anyone booting NX-capable
CPUs in 32bit mode without PAE will lack NX functionality, so this change
provides feedback for that case as well.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <1258154897-6770-6-git-send-email-hpa@zytor.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 23b7f46bf843..d2043a00abc1 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -788,16 +788,17 @@ void __init setup_arch(char **cmdline_p)
 	*cmdline_p = command_line;
 
 	/*
-	 * 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.
+	 * x86_configure_nx() is called before parse_early_param() to detect
+	 * whether hardware doesn't support NX (so that the early EHCI debug
+	 * console setup can safely call set_fixmap()). It may then be called
+	 * again from within noexec_setup() during parsing early parameters
+	 * to honor the respective command line option.
 	 */
 	x86_configure_nx();
 
 	parse_early_param();
 
-	x86_configure_nx();
+	x86_report_nx();
 
 	/* Must be before kernel pagetables are setup */
 	vmi_activate();