rust: add compiler_builtins crate

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 our own crate.

Reviewed-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
Co-developed-by: Sven Van Asbroeck <thesven73@gmail.com>
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
Co-developed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Miguel Ojeda 2021-07-03 16:54:11 +02:00
parent 057b8d2571
commit db958dcf88

63
rust/compiler_builtins.rs Normal file
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// 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/
#![feature(compiler_builtins)]
#![compiler_builtins]
#![no_builtins]
#![no_std]
macro_rules! define_panicking_intrinsics(
($reason: tt, { $($ident: ident, )* }) => {
$(
#[doc(hidden)]
#[no_mangle]
pub extern "C" fn $ident() {
panic!($reason);
}
)*
}
);
define_panicking_intrinsics!("`f32` should not be used", {
__eqsf2,
__gesf2,
__lesf2,
__nesf2,
__unordsf2,
});
define_panicking_intrinsics!("`f64` should not be used", {
__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,
});