arm64: rust: Enable Rust support for AArch64

This commit provides the build flags for Rust for AArch64. The core Rust
support already in the kernel does the rest. This enables the PAC ret
and BTI options in the Rust build flags to match the options that are
used when building C.

The Rust samples have been tested with this commit.

Signed-off-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Tested-by: Dirk Behme <dirk.behme@de.bosch.com>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Fabien Parent <fabien.parent@linaro.org>
Link: https://lore.kernel.org/r/20231020155056.3495121-3-Jamie.Cunliffe@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
index 73203ba1e9011e3a5eb5d58f598f00f34b4ece80..5c4fa9f5d1cdb7a1691c95d09180be804b2f9e55 100644 (file)
--- a/Documentation/rust/arch-support.rst
+++ b/Documentation/rust/arch-support.rst
@@ -15,6 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
 =============  ================  ==============================================
 Architecture   Level of support  Constraints
 =============  ================  ==============================================
+``arm64``      Maintained        Little Endian only.
 ``loongarch``  Maintained        -
 ``um``         Maintained        ``x86_64`` only.
 ``x86``        Maintained        ``x86_64`` only.

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index aa7c1d435139684d7b56f96f3f93945d331d64d6..8a5f3823242c8e16b2bc33705cf30e31b4ce99ed 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -229,6 +229,7 @@ config ARM64
        select HAVE_FUNCTION_ARG_ACCESS_API
        select MMU_GATHER_RCU_TABLE_FREE
        select HAVE_RSEQ
+       select HAVE_RUST if CPU_LITTLE_ENDIAN
        select HAVE_STACKPROTECTOR
        select HAVE_SYSCALL_TRACEPOINTS
        select HAVE_KPROBES

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index a88cdf91068713ebefc031f438b3b22a0247f943..0e075d3c546b4820c1559a3811eb7c9fdebd2f4a 100644 (file)
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -41,6 +41,8 @@ KBUILD_CFLAGS += -mgeneral-regs-only  \
 KBUILD_CFLAGS  += $(call cc-disable-warning, psabi)
 KBUILD_AFLAGS  += $(compat_vdso)
 
+KBUILD_RUSTFLAGS += --target=aarch64-unknown-none -Ctarget-feature="-neon"
+
 KBUILD_CFLAGS  += $(call cc-option,-mabi=lp64)
 KBUILD_AFLAGS  += $(call cc-option,-mabi=lp64)
 
@@ -65,7 +67,9 @@ endif
 
 ifeq ($(CONFIG_ARM64_BTI_KERNEL),y)
   KBUILD_CFLAGS += -mbranch-protection=pac-ret+bti
+  KBUILD_RUSTFLAGS += -Zbranch-protection=bti,pac-ret
 else ifeq ($(CONFIG_ARM64_PTR_AUTH_KERNEL),y)
+  KBUILD_RUSTFLAGS += -Zbranch-protection=pac-ret
   ifeq ($(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET),y)
     KBUILD_CFLAGS += -mbranch-protection=pac-ret
   else

diff --git a/rust/Makefile b/rust/Makefile
index 88f88a26e5032ee0ad9d228c30eedf33782d8cd4..fe045dbc701ead1d8d4c43cae990e557045425dc 100644 (file)
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -297,6 +297,7 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \
 
 # Derived from `scripts/Makefile.clang`.
 BINDGEN_TARGET_x86     := x86_64-linux-gnu
+BINDGEN_TARGET_arm64   := aarch64-linux-gnu
 BINDGEN_TARGET         := $(BINDGEN_TARGET_$(SRCARCH))
 
 # All warnings are inhibited since GCC builds are very experimental,

diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 0da52b548ba50f5e1333c3c2b2a18da2533a18a1..9e117957ea7ba28e3d02ac23ebfb9114ffa5592b 100644 (file)
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -148,7 +148,9 @@ fn main() {
     let mut ts = TargetSpec::new();
 
     // `llvm-target`s are taken from `scripts/Makefile.clang`.
-    if cfg.has("X86_64") {
+    if cfg.has("ARM64") {
+        panic!("arm64 uses the builtin rustc aarch64-unknown-none target");
+    } else if cfg.has("X86_64") {
         ts.push("arch", "x86_64");
         ts.push(
             "data-layout",