Files
linux/rust/compiler_builtins.rs
Link Mauve c93c194e4e rust: Make __udivdi3() and __umoddi3() panic
The core crate currently depends on these two functions for i64/u64/
i128/u128/core::time::Duration formatting, but we shouldn’t use that in
the kernel so let’s panic if they are ever called.

This doesn’t yet fix drm_panic_qr.rs, which also uses __udivdi3 when
CONFIG_CC_OPTIMIZE_FOR_SIZE=y, but at least makes the rest of the kernel
build on PPC32.

Signed-off-by: Link Mauve <linkmauve@linkmauve.fr>
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260708082454.1254320-6-mkchauras@gmail.com
2026-07-31 16:57:48 +05:30

108 lines
2.7 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,
});
#[cfg(target_arch = "powerpc")]
define_panicking_intrinsics!("`u64` division/modulo should not be used", {
__udivdi3,
__umoddi3,
});
// NOTE: if you are adding a new intrinsic here, you should also add it to
// `redirect-intrinsics` in `rust/Makefile`.