1 files changed, 126 insertions, 0 deletions
diff --git a/rust/kernel/bug.rs b/rust/kernel/bug.rs
new file mode 100644
index 000000000000..36aef43e5ebe
--- /dev/null
+++ b/rust/kernel/bug.rs
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2024, 2025 FUJITA Tomonori <fujita.tomonori@gmail.com>
+
+//! Support for BUG and WARN functionality.
+//!
+//! C header: [`include/asm-generic/bug.h`](srctree/include/asm-generic/bug.h)
+
+#[macro_export]
+#[doc(hidden)]
+#[cfg(all(CONFIG_BUG, not(CONFIG_UML), not(CONFIG_LOONGARCH), not(CONFIG_ARM)))]
+#[cfg(CONFIG_DEBUG_BUGVERBOSE)]
+macro_rules! warn_flags {
+    ($flags:expr) => {
+        const FLAGS: u32 = $crate::bindings::BUGFLAG_WARNING | $flags;
+        const _FILE: &[u8] = file!().as_bytes();
+        // Plus one for null-terminator.
+        static FILE: [u8; _FILE.len() + 1] = {
+            let mut bytes = [0; _FILE.len() + 1];
+            let mut i = 0;
+            while i < _FILE.len() {
+                bytes[i] = _FILE[i];
+                i += 1;
+            }
+            bytes
+        };
+
+        // SAFETY:
+        // - `file`, `line`, `flags`, and `size` are all compile-time constants or
+        // symbols, preventing any invalid memory access.
+        // - The asm block has no side effects and does not modify any registers
+        // or memory. It is purely for embedding metadata into the ELF section.
+        unsafe {
+            $crate::asm!(
+                concat!(
+                    "/* {size} */",
+                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_warn_asm.rs")),
+                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_reachable_asm.rs")));
+                file = sym FILE,
+                line = const line!(),
+                flags = const FLAGS,
+                size = const ::core::mem::size_of::<$crate::bindings::bug_entry>(),
+            );
+        }
+    }
+}
+
+#[macro_export]
+#[doc(hidden)]
+#[cfg(all(CONFIG_BUG, not(CONFIG_UML), not(CONFIG_LOONGARCH), not(CONFIG_ARM)))]
+#[cfg(not(CONFIG_DEBUG_BUGVERBOSE))]
+macro_rules! warn_flags {
+    ($flags:expr) => {
+        const FLAGS: u32 = $crate::bindings::BUGFLAG_WARNING | $flags;
+
+        // SAFETY:
+        // - `flags` and `size` are all compile-time constants, preventing
+        // any invalid memory access.
+        // - The asm block has no side effects and does not modify any registers
+        // or memory. It is purely for embedding metadata into the ELF section.
+        unsafe {
+            $crate::asm!(
+                concat!(
+                    "/* {size} */",
+                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_warn_asm.rs")),
+                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_reachable_asm.rs")));
+                flags = const FLAGS,
+                size = const ::core::mem::size_of::<$crate::bindings::bug_entry>(),
+            );
+        }
+    }
+}
+
+#[macro_export]
+#[doc(hidden)]
+#[cfg(all(CONFIG_BUG, CONFIG_UML))]
+macro_rules! warn_flags {
+    ($flags:expr) => {
+        // SAFETY: It is always safe to call `warn_slowpath_fmt()`
+        // with a valid null-terminated string.
+        unsafe {
+            $crate::bindings::warn_slowpath_fmt(
+                $crate::c_str!(::core::file!()).as_char_ptr(),
+                line!() as $crate::ffi::c_int,
+                $flags as $crate::ffi::c_uint,
+                ::core::ptr::null(),
+            );
+        }
+    };
+}
+
+#[macro_export]
+#[doc(hidden)]
+#[cfg(all(CONFIG_BUG, any(CONFIG_LOONGARCH, CONFIG_ARM)))]
+macro_rules! warn_flags {
+    ($flags:expr) => {
+        // SAFETY: It is always safe to call `WARN_ON()`.
+        unsafe { $crate::bindings::WARN_ON(true) }
+    };
+}
+
+#[macro_export]
+#[doc(hidden)]
+#[cfg(not(CONFIG_BUG))]
+macro_rules! warn_flags {
+    ($flags:expr) => {};
+}
+
+#[doc(hidden)]
+pub const fn bugflag_taint(value: u32) -> u32 {
+    value << 8
+}
+
+/// Report a warning if `cond` is true and return the condition's evaluation result.
+#[macro_export]
+macro_rules! warn_on {
+    ($cond:expr) => {{
+        let cond = $cond;
+        if cond {
+            const WARN_ON_FLAGS: u32 = $crate::bug::bugflag_taint($crate::bindings::TAINT_WARN);
+
+            $crate::warn_flags!(WARN_ON_FLAGS);
+        }
+        cond
+    }};
+}