x86, cpu: Enable/disable Supervisor Mode Execution Protection

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Enable/disable newly documented SMEP (Supervisor Mode Execution Protection) CPU
feature in kernel. CR4.SMEP (bit 20) is 0 at power-on. If the feature is
supported by CPU (X86_FEATURE_SMEP), enable SMEP by setting CR4.SMEP. New kernel
option nosmep disables the feature even if the feature is supported by CPU.

[ hpa: moved the call to setup_smep() until after the vendor-specific
  initialization; that ensures that CPUID features are unmasked.  We
  will still run it before we have userspace (never mind uncontrolled
  userspace). ]

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
LKML-Reference: <1305157865-31727-1-git-send-email-fenghua.yu@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

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Fenghua Yu 2011-05-11 16:51:05 -07:00 • committed by H. Peter Anvin

parent dc23c0bccf

commit de5397ad5b

2 changed files with 27 additions and 0 deletions

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4

Documentation/kernel-parameters.txt

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23

arch/x86/kernel/cpu/common.c

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