compiler_builtins.rs

  1// SPDX-License-Identifier: GPL-2.0
  2
  3//! Our own `compiler_builtins`.
  4//!
  5//! Rust provides [`compiler_builtins`] as a port of LLVM's [`compiler-rt`].
  6//! Since we do not need the vast majority of them, we avoid the dependency
  7//! by providing this file.
  8//!
  9//! At the moment, some builtins are required that should not be. For instance,
 10//! [`core`] has 128-bit integers functionality which we should not be compiling
 11//! in. We will work with upstream [`core`] to provide feature flags to disable
 12//! the parts we do not need. For the moment, we define them to [`panic!`] at
 13//! runtime for simplicity to catch mistakes, instead of performing surgery
 14//! on `core.o`.
 15//!
 16//! In any case, all these symbols are weakened to ensure we do not override
 17//! those that may be provided by the rest of the kernel.
 18//!
 19//! [`compiler_builtins`]: https://github.com/rust-lang/compiler-builtins
 20//! [`compiler-rt`]: https://compiler-rt.llvm.org/
 21
 22#![allow(internal_features)]
 23#![feature(compiler_builtins)]
 24#![compiler_builtins]
 25#![no_builtins]
 26#![no_std]
 27
 28macro_rules! define_panicking_intrinsics(
 29    ($reason: tt, { $($ident: ident, )* }) => {
 30        $(
 31            #[doc(hidden)]
 32            #[export_name = concat!("__rust", stringify!($ident))]
 33            pub extern "C" fn $ident() {
 34                panic!($reason);
 35            }
 36        )*
 37    }
 38);
 39
 40define_panicking_intrinsics!("`f32` should not be used", {
 41    __addsf3,
 42    __eqsf2,
 43    __extendsfdf2,
 44    __gesf2,
 45    __lesf2,
 46    __ltsf2,
 47    __mulsf3,
 48    __nesf2,
 49    __truncdfsf2,
 50    __unordsf2,
 51});
 52
 53define_panicking_intrinsics!("`f64` should not be used", {
 54    __adddf3,
 55    __eqdf2,
 56    __ledf2,
 57    __ltdf2,
 58    __muldf3,
 59    __unorddf2,
 60});
 61
 62define_panicking_intrinsics!("`i128` should not be used", {
 63    __ashrti3,
 64    __muloti4,
 65    __multi3,
 66});
 67
 68define_panicking_intrinsics!("`u128` should not be used", {
 69    __ashlti3,
 70    __lshrti3,
 71    __udivmodti4,
 72    __udivti3,
 73    __umodti3,
 74});
 75
 76#[cfg(target_arch = "arm")]
 77define_panicking_intrinsics!("`f32` should not be used", {
 78    __aeabi_fadd,
 79    __aeabi_fmul,
 80    __aeabi_fcmpeq,
 81    __aeabi_fcmple,
 82    __aeabi_fcmplt,
 83    __aeabi_fcmpun,
 84});
 85
 86#[cfg(target_arch = "arm")]
 87define_panicking_intrinsics!("`f64` should not be used", {
 88    __aeabi_dadd,
 89    __aeabi_dmul,
 90    __aeabi_dcmple,
 91    __aeabi_dcmplt,
 92    __aeabi_dcmpun,
 93});
 94
 95#[cfg(target_arch = "arm")]
 96define_panicking_intrinsics!("`u64` division/modulo should not be used", {
 97    __aeabi_uldivmod,
 98});
 99
100// NOTE: if you are adding a new intrinsic here, you should also add it to
101// `redirect-intrinsics` in `rust/Makefile`.