x86/mpx: remove build infrastructure

From: Dave Hansen <dave.hansen@linux.intel.com>

MPX is being removed from the kernel due to a lack of support
in the toolchain going forward (gcc).

Remove the Kconfig option and the Makefile line.  This makes
arch/x86/mm/mpx.c and anything under an #ifdef for
X86_INTEL_MPX dead code.

Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8ef8513..1c25ca1 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1896,34 +1896,6 @@ config X86_INTEL_UMIP
          specific cases in protected and virtual-8086 modes. Emulated
          results are dummy.
 
-config X86_INTEL_MPX
-       prompt "Intel MPX (Memory Protection Extensions)"
-       def_bool n
-       # Note: only available in 64-bit mode due to VMA flags shortage
-       depends on CPU_SUP_INTEL && X86_64
-       select ARCH_USES_HIGH_VMA_FLAGS
-       ---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.rst
-
-         If unsure, say N.
-
 config X86_INTEL_MEMORY_PROTECTION_KEYS
        prompt "Intel Memory Protection Keys"
        def_bool y

diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 84373dc..236e577 100644 (file)
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -45,7 +45,6 @@ obj-$(CONFIG_AMD_NUMA)                += amdtopology.o
 obj-$(CONFIG_ACPI_NUMA)                += srat.o
 obj-$(CONFIG_NUMA_EMU)         += numa_emulation.o
 
-obj-$(CONFIG_X86_INTEL_MPX)                    += mpx.o
 obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o
 obj-$(CONFIG_RANDOMIZE_MEMORY)                 += kaslr.o
 obj-$(CONFIG_PAGE_TABLE_ISOLATION)             += pti.o