[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20250731111234.28602-1-ritvikfoss@gmail.com>
Date: Thu, 31 Jul 2025 16:42:28 +0530
From: Ritvik Gupta <ritvikfoss@...il.com>
To: Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <lossin@...nel.org>,
Andreas Hindborg <a.hindborg@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>,
Danilo Krummrich <dakr@...nel.org>
Cc: skhan@...uxfoundation.org,
linux-kernel@...r.kernel.org,
rust-for-linux@...r.kernel.org
Subject: [PATCH v3] rust: kernel: introduce `unsafe_precondition_assert!` macro
Introduce a new `safety` module containing `unsafe_precondition_assert!`
macro. It is a wrapper around `debug_assert!`, intended for validating
pre-conditions of unsafe function.
When `CONFIG_RUST_DEBUG_ASSERTIONS` flag is enabled, this macro performs
runtime checks to ensure that the preconditions for unsafe function hold.
Otherwise, the macro is a no-op.
Suggested-by: Miguel Ojeda <ojeda@...nel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1162
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/291566-Library/topic/.60unsafe_precondition_assert.60.20macro/with/528457452
Signed-off-by: Ritvik Gupta <ritvikfoss@...il.com>
---
Changes in v3:
- Change doc example
- Link to v2: https://lore.kernel.org/all/20250730181420.6979b4f1@eugeo/T/#m9cd35a8fc02a18bd03934c7ecdcffe8667b5fbbd
Changes in v2:
- Wrap `debug_assert!` internally instead of using `pr_err!` with `assert!` + `cfg!(debug_assertions)
- Print “unsafe precondition(s) violated” only on assertion failure (no longer always printed)
- Use `# Safety` section instead of comment in the example
- Rename module-level doc
- Link to v1: https://lore.kernel.org/rust-for-linux/20250716045957.39732-1-ritvikfoss@gmail.com/
---
rust/kernel/lib.rs | 1 +
rust/kernel/safety.rs | 47 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 48 insertions(+)
create mode 100644 rust/kernel/safety.rs
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 11a6461e98da..7aab607dd879 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -104,6 +104,7 @@
pub mod print;
pub mod rbtree;
pub mod revocable;
+pub mod safety;
pub mod security;
pub mod seq_file;
pub mod sizes;
diff --git a/rust/kernel/safety.rs b/rust/kernel/safety.rs
new file mode 100644
index 000000000000..f591eed6da77
--- /dev/null
+++ b/rust/kernel/safety.rs
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Safety related APIs.
+
+/// Checks that preconditions of an unsafe function are followed.
+///
+/// The check is enabled at runtime if debug assertions (`CONFIG_RUST_DEBUG_ASSERTIONS`)
+/// are enabled. Otherwise, this macro is no-op.
+///
+/// # Examples
+///
+/// ```
+/// /// # Safety
+/// ///
+/// /// - `buf` must be non-null.
+/// /// - `buf` must be 16-byte aligned.
+/// /// - `len` must be multiple of [`PAGE_SIZE`].
+/// unsafe fn foo(buf: *const u8, len: usize) {
+/// unsafe_precondition_assert!(!buf.is_null(), "buf must not be null");
+/// unsafe_precondition_assert!((buf as usize) % 16 == 0, "buf must be 16-byte aligned");
+/// unsafe_precondition_assert!(
+/// len % PAGE_SIZE == 0,
+/// "len ({}) must be multiple of PAGE_SIZE ({})",
+/// len,
+/// PAGE_SIZE
+/// );
+/// // ...
+/// }
+/// ```
+///
+/// # Panics
+///
+/// Panics if the expression is evaluated to `false` at runtime.
+///
+#[macro_export]
+macro_rules! unsafe_precondition_assert {
+ ($cond:expr $(,)?) => {
+ $crate::unsafe_precondition_assert!(@inner $cond, ::core::stringify!($cond))
+ };
+
+ ($cond:expr, $($arg:tt)+) => {
+ $crate::unsafe_precondition_assert!(@inner $cond, ::core::format_args!($($arg)+))
+ };
+
+ (@inner $cond:expr, $msg:expr) => {
+ ::core::debug_assert!($cond, "unsafe precondition(s) violated: {}", $msg) };
+}
base-commit: dff64b072708ffef23c117fa1ee1ea59eb417807
--
2.50.1
Powered by blists - more mailing lists