2 files changed, 31 insertions, 5 deletions

diff --git a/Documentation/x86/intel_mpx.txt b/Documentation/x86/intel_mpx.txt
index 6ca6e2bd9ae9..818518a3ff01 100644
--- a/Documentation/x86/intel_mpx.txt
+++ b/Documentation/x86/intel_mpx.txt
@@ -7,11 +7,15 @@ that can be used in conjunction with compiler changes to check memory
 references, for those references whose compile-time normal intentions are
 usurped at runtime due to buffer overflow or underflow.
 
+You can tell if your CPU supports MPX by looking in /proc/cpuinfo:
+
+        cat /proc/cpuinfo  | grep ' mpx '
+
 For more information, please refer to Intel(R) Architecture Instruction
 Set Extensions Programming Reference, Chapter 9: Intel(R) Memory Protection
 Extensions.
 
-Note: Currently no hardware with MPX ISA is available but it is always
+Note: As of December 2014, no hardware with MPX is available but it is
 possible to use SDE (Intel(R) Software Development Emulator) instead, which
 can be downloaded from
 http://software.intel.com/en-us/articles/intel-software-development-emulator
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 967dfe0ba85e..cc91e5e55d13 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -248,10 +248,6 @@ config HAVE_INTEL_TXT
         def_bool y
         depends on INTEL_IOMMU && ACPI
 
-config X86_INTEL_MPX
-        def_bool y
-        depends on CPU_SUP_INTEL
-
 config X86_32_SMP
         def_bool y
         depends on X86_32 && SMP
@@ -1575,6 +1571,32 @@ config X86_SMAP
 
           If unsure, say Y.
 
+config X86_INTEL_MPX
+        prompt "Intel MPX (Memory Protection Extensions)"
+        def_bool n
+        depends on CPU_SUP_INTEL
+        ---help---
+          MPX provides hardware features that can be used in
+          conjunction with compiler-instrumented code to check
+          memory references.  It is designed to detect buffer
+          overflow or underflow bugs.
+
+          This option enables running applications which are
+          instrumented or otherwise use MPX.  It does not use MPX
+          itself inside the kernel or to protect the kernel
+          against bad memory references.
+
+          Enabling this option will make the kernel larger:
+          ~8k of kernel text and 36 bytes of data on a 64-bit
+          defconfig.  It adds a long to the 'mm_struct' which
+          will increase the kernel memory overhead of each
+          process and adds some branches to paths used during
+          exec() and munmap().
+
+          For details, see Documentation/x86/intel_mpx.txt
+
+          If unsure, say N.
+
 config EFI
         bool "EFI runtime service support"
         depends on ACPI