linux-stable-mirror/rust/compiler_builtins.rs
Christian Schrrefl ccb8ce5268 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 <guptarud@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Tested-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Christian Schrefl <chrisi.schrefl@gmail.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
2025-03-26 13:31:16 +00:00

102 lines
2.5 KiB
Rust

// SPDX-License-Identifier: GPL-2.0
//! Our own `compiler_builtins`.
//!
//! Rust provides [`compiler_builtins`] as a port of LLVM's [`compiler-rt`].
//! Since we do not need the vast majority of them, we avoid the dependency
//! by providing this file.
//!
//! At the moment, some builtins are required that should not be. For instance,
//! [`core`] has 128-bit integers functionality which we should not be compiling
//! in. We will work with upstream [`core`] to provide feature flags to disable
//! the parts we do not need. For the moment, we define them to [`panic!`] at
//! runtime for simplicity to catch mistakes, instead of performing surgery
//! on `core.o`.
//!
//! In any case, all these symbols are weakened to ensure we do not override
//! those that may be provided by the rest of the kernel.
//!
//! [`compiler_builtins`]: https://github.com/rust-lang/compiler-builtins
//! [`compiler-rt`]: https://compiler-rt.llvm.org/
#![allow(internal_features)]
#![feature(compiler_builtins)]
#![compiler_builtins]
#![no_builtins]
#![no_std]
macro_rules! define_panicking_intrinsics(
($reason: tt, { $($ident: ident, )* }) => {
$(
#[doc(hidden)]
#[export_name = concat!("__rust", stringify!($ident))]
pub extern "C" fn $ident() {
panic!($reason);
}
)*
}
);
define_panicking_intrinsics!("`f32` should not be used", {
__addsf3,
__eqsf2,
__extendsfdf2,
__gesf2,
__lesf2,
__ltsf2,
__mulsf3,
__nesf2,
__truncdfsf2,
__unordsf2,
});
define_panicking_intrinsics!("`f64` should not be used", {
__adddf3,
__eqdf2,
__ledf2,
__ltdf2,
__muldf3,
__unorddf2,
});
define_panicking_intrinsics!("`i128` should not be used", {
__ashrti3,
__muloti4,
__multi3,
});
define_panicking_intrinsics!("`u128` should not be used", {
__ashlti3,
__lshrti3,
__udivmodti4,
__udivti3,
__umodti3,
});
#[cfg(target_arch = "arm")]
define_panicking_intrinsics!("`f32` should not be used", {
__aeabi_fadd,
__aeabi_fmul,
__aeabi_fcmpeq,
__aeabi_fcmple,
__aeabi_fcmplt,
__aeabi_fcmpun,
});
#[cfg(target_arch = "arm")]
define_panicking_intrinsics!("`f64` should not be used", {
__aeabi_dadd,
__aeabi_dmul,
__aeabi_dcmple,
__aeabi_dcmplt,
__aeabi_dcmpun,
});
#[cfg(target_arch = "arm")]
define_panicking_intrinsics!("`u64` division/modulo should not be used", {
__aeabi_uldivmod,
});
// NOTE: if you are adding a new intrinsic here, you should also add it to
// `redirect-intrinsics` in `rust/Makefile`.