diff options
| -rw-r--r-- | arch/x86/Kconfig.cpu | 11 | ||||
| -rw-r--r-- | arch/x86/Makefile | 5 | ||||
| -rw-r--r-- | scripts/generate_rust_target.rs | 5 |
3 files changed, 21 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu index e4654388d..6e7a366f0 100644 --- a/arch/x86/Kconfig.cpu +++ b/arch/x86/Kconfig.cpu @@ -204,10 +204,21 @@ config CC_HAS_MARCH_NATIVE # usage warnings that only appear wth '-march=native'. depends on CC_IS_GCC || CLANG_VERSION >= 190100 +config RUSTC_HAS_APXF + # The kernel isn't ready for in-kernel APX instructions. Without + # explicit frontend gating of APX, the backend may emit those + # instructions in native builds. + # + # Rust 1.88 added the `apxf` feature option, but versions before 1.93 + # emit an `apxf` target attribute that only LLVM 23+ can interpret. + def_bool (RUSTC_VERSION >= 108800 && RUSTC_LLVM_MAJOR_VERSION >= 23) || \ + RUSTC_VERSION >= 109300 + config X86_NATIVE_CPU bool "Build and optimize for local/native CPU" depends on X86_64 depends on CC_HAS_MARCH_NATIVE + depends on !RUST || RUSTC_HAS_APXF help Optimize for the current CPU used to compile the kernel. Use this option if you intend to build the kernel for your diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 598f17810..8af6b80cf 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -161,6 +161,11 @@ else ifdef CONFIG_X86_NATIVE_CPU KBUILD_CFLAGS += -march=native + # Prevent the compiler from generating EGPR use. The kernel is + # not yet prepared for general in-kernel use. + KBUILD_CFLAGS += $(call cc-option,-mno-apx-features=egpr) + + # generate_rust_target.rs handles Rust APX gating. KBUILD_RUSTFLAGS += -Ctarget-cpu=native else KBUILD_CFLAGS += -march=x86-64 -mtune=generic diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs index 3bf296581..7687b0dd5 100644 --- a/scripts/generate_rust_target.rs +++ b/scripts/generate_rust_target.rs @@ -224,6 +224,11 @@ fn main() { features += ",+harden-sls-ijmp"; features += ",+harden-sls-ret"; } + if cfg.has("X86_NATIVE_CPU") { + // Prevent the backend from generating APX instructions. The kernel is not yet prepared + // for general in-kernel EGPR use. + features += ",-apxf"; + } ts.push("features", features); ts.push("llvm-target", "x86_64-linux-gnu"); ts.push("supported-sanitizers", ["kcfi", "kernel-address"]); |