arm64: mte: Kconfig entry

Add Memory Tagging Extension support to the arm64 kbuild.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d23283..e7450fb 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1664,6 +1664,39 @@ config ARCH_RANDOM
          provides a high bandwidth, cryptographically secure
          hardware random number generator.
 
+config ARM64_AS_HAS_MTE
+       # Initial support for MTE went in binutils 2.32.0, checked with
+       # ".arch armv8.5-a+memtag" below. However, this was incomplete
+       # as a late addition to the final architecture spec (LDGM/STGM)
+       # is only supported in the newer 2.32.x and 2.33 binutils
+       # versions, hence the extra "stgm" instruction check below.
+       def_bool $(as-instr,.arch armv8.5-a+memtag\nstgm xzr$(comma)[x0])
+
+config ARM64_MTE
+       bool "Memory Tagging Extension support"
+       default y
+       depends on ARM64_AS_HAS_MTE && ARM64_TAGGED_ADDR_ABI
+       select ARCH_USES_HIGH_VMA_FLAGS
+       help
+         Memory Tagging (part of the ARMv8.5 Extensions) provides
+         architectural support for run-time, always-on detection of
+         various classes of memory error to aid with software debugging
+         to eliminate vulnerabilities arising from memory-unsafe
+         languages.
+
+         This option enables the support for the Memory Tagging
+         Extension at EL0 (i.e. for userspace).
+
+         Selecting this option allows the feature to be detected at
+         runtime. Any secondary CPU not implementing this feature will
+         not be allowed a late bring-up.
+
+         Userspace binaries that want to use this feature must
+         explicitly opt in. The mechanism for the userspace is
+         described in:
+
+         Documentation/arm64/memory-tagging-extension.rst.
+
 endmenu
 
 config ARM64_SVE