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x86, mm: Report state of NX protections during boot

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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>
This commit is contained in:
Kees Cook
2009-11-13 15:28:17 -08:00
committed by H. Peter Anvin
parent 4763ed4d45
commit 4b0f3b81eb
4 changed files with 29 additions and 9 deletions
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4
arch/x86/mm/init.c
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@@ -146,10 +146,6 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
use_gbpages = direct_gbpages;
#endif
/* XXX: replace this with Kees' improved messages */
if (__supported_pte_mask & _PAGE_NX)
printk(KERN_INFO "NX (Execute Disable) protection: active\n");
/* Enable PSE if available */
if (cpu_has_pse)
set_in_cr4(X86_CR4_PSE);