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From: Miguel Ojeda <ojeda@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Miguel Ojeda <ojeda@kernel.org>,
	Alex Gaynor <alex.gaynor@gmail.com>,
	Wedson Almeida Filho <wedsonaf@google.com>,
	Sven Van Asbroeck <thesven73@gmail.com>,
	Gary Guo <gary@garyguo.net>
Subject: [PATCH 05/19] rust: add `compiler_builtins` crate
Date: Mon,  6 Dec 2021 15:02:59 +0100	[thread overview]
Message-ID: <20211206140313.5653-6-ojeda@kernel.org> (raw)
In-Reply-To: <20211206140313.5653-1-ojeda@kernel.org>

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.

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>
---
 rust/compiler_builtins.rs | 57 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 rust/compiler_builtins.rs

diff --git a/rust/compiler_builtins.rs b/rust/compiler_builtins.rs
new file mode 100644
index 000000000000..a5a0be72591b
--- /dev/null
+++ b/rust/compiler_builtins.rs
@@ -0,0 +1,57 @@
+// 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 floating-point 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!("`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!("`u64` division/modulo should not be used", {
+    __aeabi_uldivmod,
+    __mulodi4,
+});
-- 
2.34.0


  parent reply	other threads:[~2021-12-06 14:05 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-06 14:02 [PATCH 00/19] Rust support Miguel Ojeda
2021-12-06 14:02 ` [PATCH 01/19] kallsyms: support "big" kernel symbols Miguel Ojeda
2021-12-06 14:18   ` Matthew Wilcox
2021-12-06 17:00     ` Miguel Ojeda
2021-12-06 14:02 ` [PATCH 02/19] kallsyms: increase maximum kernel symbol length to 512 Miguel Ojeda
2021-12-06 14:02 ` [PATCH 03/19] kallsyms: use the correct buffer size for symbols Miguel Ojeda
2021-12-06 14:02 ` [PATCH 04/19] rust: add C helpers Miguel Ojeda
2021-12-06 14:02 ` Miguel Ojeda [this message]
2021-12-07 23:01   ` [PATCH 05/19] rust: add `compiler_builtins` crate Nick Desaulniers
2021-12-09 19:34     ` Miguel Ojeda
2021-12-06 14:03 ` [PATCH 07/19] rust: add `build_error` crate Miguel Ojeda
2021-12-06 14:03 ` [PATCH 08/19] rust: add `macros` crate Miguel Ojeda
2021-12-06 14:03 ` [PATCH 10/19] rust: export generated symbols Miguel Ojeda
2021-12-06 14:03 ` [PATCH 11/19] vsprintf: add new `%pA` format specifier Miguel Ojeda
2021-12-06 15:02   ` Greg Kroah-Hartman
2021-12-06 15:56     ` Miguel Ojeda
2021-12-06 16:02       ` Greg Kroah-Hartman
2021-12-06 19:52         ` Nick Desaulniers
2021-12-06 19:55           ` Matthew Wilcox
2021-12-06 20:02             ` Nick Desaulniers
2021-12-06 14:03 ` [PATCH 12/19] scripts: add `generate_rust_analyzer.py` Miguel Ojeda
2021-12-06 14:03 ` [PATCH 13/19] scripts: decode_stacktrace: demangle Rust symbols Miguel Ojeda
2021-12-06 14:03 ` [PATCH 14/19] docs: add Rust documentation Miguel Ojeda
2021-12-08  1:29   ` Nick Desaulniers
2021-12-08 23:07     ` Miguel Ojeda
2021-12-06 14:03 ` [PATCH 15/19] Kbuild: add Rust support Miguel Ojeda
2021-12-07 22:45   ` Nick Desaulniers
2021-12-07 23:21     ` Nick Desaulniers
2021-12-07 23:25       ` Wedson Almeida Filho
2021-12-08  0:05         ` Nick Desaulniers
2021-12-08 22:52     ` Miguel Ojeda
2021-12-11 15:53   ` Masahiro Yamada
2022-01-17  4:45     ` Miguel Ojeda
2021-12-06 14:03 ` [PATCH 16/19] samples: add Rust examples Miguel Ojeda
2021-12-06 14:03 ` [PATCH 17/19] MAINTAINERS: Rust Miguel Ojeda
2021-12-06 14:03 ` [RFC PATCH 18/19] drivers: gpio: PrimeCell PL061 in Rust Miguel Ojeda
     [not found] ` <20211206140313.5653-20-ojeda@kernel.org>
2021-12-06 15:01   ` [RFC PATCH 19/19] drivers: android: Binder IPC " Greg Kroah-Hartman
2021-12-06 15:59     ` Wedson Almeida Filho
2021-12-06 16:02       ` Greg Kroah-Hartman

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