diff options
2 files changed, 31 insertions, 5 deletions
diff --git a/Documentation/x86/intel_mpx.txt b/Documentation/x86/intel_mpx.txt
index 6ca6e2b..818518a 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
-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
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 967dfe0..cc91e5e 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

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