[PATCH 1/3] arm64: rust: Enable Rust support for AArch64

[Jamie Cunliffe <Jamie.Cunliffe@arm.com>]

From: Miguel Ojeda <ojeda@kernel.org>

This commit provides the build flags for Rust for AArch64. The core Rust
support already in the kernel does the rest.

The Rust samples have been tested with this commit.

[jcunliffe: Arm specific parts taken from Miguel's upstream tree]

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Co-developed-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
Signed-off-by: Jamie Cunliffe <Jamie.Cunliffe@arm.com>
---
 Documentation/rust/arch-support.rst |  1 +
 arch/arm64/Kconfig                  |  1 +
 scripts/generate_rust_target.rs     | 13 ++++++++++++-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
index 6982b63775da..3776059a385a 100644
--- a/Documentation/rust/arch-support.rst
+++ b/Documentation/rust/arch-support.rst
@@ -15,5 +15,6 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
 ============  ================  ==============================================
 Architecture  Level of support  Constraints
 ============  ================  ==============================================
+``arm64``     Maintained        None.
 ``x86``       Maintained        ``x86_64`` only.
 ============  ================  ==============================================
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 03934808b2ed..fc3800e82802 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -209,6 +209,7 @@ config ARM64
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select MMU_GATHER_RCU_TABLE_FREE
 	select HAVE_RSEQ
+	select HAVE_RUST
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES
diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 3c6cbe2b278d..fe0e4ba54492 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -148,7 +148,18 @@ 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") {
+        ts.push("arch", "aarch64");
+        ts.push(
+            "data-layout",
+            "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128",
+        );
+        ts.push("disable-redzone", true);
+        ts.push("features", "+strict-align,+neon,+fp-armv8");
+        ts.push("llvm-target", "aarch64-linux-gnu");
+        ts.push("max-atomic-width", 128);
+        ts.push("target-pointer-width", "64");
+    } else if cfg.has("X86_64") {
         ts.push("arch", "x86_64");
         ts.push(
             "data-layout",
-- 
2.30.2