ARM: 9441/1: rust: Enable Rust support for ARMv7

This commit allows building ARMv7 kernels with Rust support.

The rust core library expects some __eabi_... functions
that are not implemented in the kernel.
Those functions are some float operations and __aeabi_uldivmod.
For now those are implemented with define_panicking_intrinsics!.

This is based on the code by Sven Van Asbroeck from the original
rust branch and inspired by the AArch version by Jamie Cunliffe.

I have tested the rust samples and a custom simple MMIO module
on hardware (De1SoC FPGA + Arm A9 CPU).

Tested-by: Rudraksha Gupta <[email protected]>
Reviewed-by: Alice Ryhl <[email protected]>
Acked-by: Miguel Ojeda <[email protected]>
Tested-by: Miguel Ojeda <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Christian Schrefl <[email protected]>
Signed-off-by: Russell King (Oracle) <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 0d00ac3723b5..f8e7fb38bf16 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -172,7 +172,9 @@ fn main() {
     let mut ts = TargetSpec::new();
 
     // `llvm-target`s are taken from `scripts/Makefile.clang`.
-    if cfg.has("ARM64") {
+    if cfg.has("ARM") {
+        panic!("arm uses the builtin rustc target");
+    } else if cfg.has("ARM64") {
         panic!("arm64 uses the builtin rustc aarch64-unknown-none target");
     } else if cfg.has("RISCV") {
         if cfg.has("64BIT") {