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x86, mpx: Give MPX a real config option prompt

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Give MPX a real config option. The CPUs that support it (referenced
here):

  https://software.intel.com/en-us/forums/topic/402393

are not available publicly yet. Right now only the software emulator
provides MPX for the general public.

[ tglx: Make it default off. There is no point in having it on right
        now as no hardware and no proper tooling support are available ]

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141212183836.2569D58D@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Dave Hansen 2014-12-12 10:38:36 -08:00 • committed by Thomas Gleixner
parent 010e593b14
commit 72e9b5fe9b
2 changed files with 31 additions and 5 deletions
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6
Documentation/x86/intel_mpx.txt
View file

@ -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 references, for those references whose compile-time normal intentions are
usurped at runtime due to buffer overflow or underflow. 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 For more information, please refer to Intel(R) Architecture Instruction
Set Extensions Programming Reference, Chapter 9: Intel(R) Memory Protection Set Extensions Programming Reference, Chapter 9: Intel(R) Memory Protection
Extensions. 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 possible to use SDE (Intel(R) Software Development Emulator) instead, which
can be downloaded from can be downloaded from
http://software.intel.com/en-us/articles/intel-software-development-emulator http://software.intel.com/en-us/articles/intel-software-development-emulator

30
arch/x86/Kconfig
View file

@ -248,10 +248,6 @@ config HAVE_INTEL_TXT
def_bool y def_bool y
depends on INTEL_IOMMU && ACPI depends on INTEL_IOMMU && ACPI
config X86_INTEL_MPX
def_bool y
depends on CPU_SUP_INTEL
config X86_32_SMP config X86_32_SMP
def_bool y def_bool y
depends on X86_32 && SMP depends on X86_32 && SMP
@ -1575,6 +1571,32 @@ config X86_SMAP
If unsure, say Y. 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 config EFI
bool "EFI runtime service support" bool "EFI runtime service support"
depends on ACPI depends on ACPI