kernel/
bug.rs

1// SPDX-License-Identifier: GPL-2.0
2
3// Copyright (C) 2024, 2025 FUJITA Tomonori <fujita.tomonori@gmail.com>
4
5//! Support for BUG and WARN functionality.
6//!
7//! C header: [`include/asm-generic/bug.h`](srctree/include/asm-generic/bug.h)
8
9#[macro_export]
10#[doc(hidden)]
11#[cfg(not(testlib))]
12#[cfg(all(CONFIG_BUG, not(CONFIG_UML), not(CONFIG_LOONGARCH), not(CONFIG_ARM)))]
13#[cfg(CONFIG_DEBUG_BUGVERBOSE)]
14macro_rules! warn_flags {
15    ($file:expr, $flags:expr) => {
16        const FLAGS: u32 = $crate::bindings::BUGFLAG_WARNING | $flags;
17        const _FILE: &[u8] = $file.as_bytes();
18        // Plus one for null-terminator.
19        static FILE: [u8; _FILE.len() + 1] = {
20            let mut bytes = [0; _FILE.len() + 1];
21            let mut i = 0;
22            while i < _FILE.len() {
23                bytes[i] = _FILE[i];
24                i += 1;
25            }
26            bytes
27        };
28
29        // SAFETY:
30        // - `file`, `line`, `flags`, and `size` are all compile-time constants or
31        // symbols, preventing any invalid memory access.
32        // - The asm block has no side effects and does not modify any registers
33        // or memory. It is purely for embedding metadata into the ELF section.
34        unsafe {
35            $crate::asm!(
36                concat!(
37                    "/* {size} */",
38                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_warn_asm.rs")),
39                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_reachable_asm.rs")));
40                file = sym FILE,
41                line = const line!(),
42                flags = const FLAGS,
43                size = const ::core::mem::size_of::<$crate::bindings::bug_entry>(),
44            );
45        }
46    }
47}
48
49#[macro_export]
50#[doc(hidden)]
51#[cfg(not(testlib))]
52#[cfg(all(CONFIG_BUG, not(CONFIG_UML), not(CONFIG_LOONGARCH), not(CONFIG_ARM)))]
53#[cfg(not(CONFIG_DEBUG_BUGVERBOSE))]
54macro_rules! warn_flags {
55    ($file:expr, $flags:expr) => {
56        const FLAGS: u32 = $crate::bindings::BUGFLAG_WARNING | $flags;
57
58        if false {
59            _ = $file;
60        }
61
62        // SAFETY:
63        // - `flags` and `size` are all compile-time constants, preventing
64        // any invalid memory access.
65        // - The asm block has no side effects and does not modify any registers
66        // or memory. It is purely for embedding metadata into the ELF section.
67        unsafe {
68            $crate::asm!(
69                concat!(
70                    "/* {size} */",
71                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_warn_asm.rs")),
72                    include!(concat!(env!("OBJTREE"), "/rust/kernel/generated_arch_reachable_asm.rs")));
73                flags = const FLAGS,
74                size = const ::core::mem::size_of::<$crate::bindings::bug_entry>(),
75            );
76        }
77    }
78}
79
80#[macro_export]
81#[doc(hidden)]
82#[cfg(not(testlib))]
83#[cfg(all(CONFIG_BUG, CONFIG_UML))]
84macro_rules! warn_flags {
85    ($file:expr, $flags:expr) => {
86        if false {
87            _ = $file;
88        }
89
90        // SAFETY: It is always safe to call `warn_slowpath_fmt()`
91        // with a valid null-terminated string.
92        unsafe {
93            $crate::bindings::warn_slowpath_fmt(
94                $crate::str::CStrExt::as_char_ptr($crate::c_str!(::core::file!())),
95                line!() as $crate::ffi::c_int,
96                $flags as $crate::ffi::c_uint,
97                ::core::ptr::null(),
98            );
99        }
100    };
101}
102
103#[macro_export]
104#[doc(hidden)]
105#[cfg(not(testlib))]
106#[cfg(all(CONFIG_BUG, any(CONFIG_LOONGARCH, CONFIG_ARM)))]
107macro_rules! warn_flags {
108    ($file:expr, $flags:expr) => {
109        if false {
110            _ = $file;
111            _ = $flags;
112        }
113
114        // SAFETY: It is always safe to call `WARN_ON()`.
115        unsafe { $crate::bindings::WARN_ON(true) }
116    };
117}
118
119#[macro_export]
120#[doc(hidden)]
121#[cfg(any(testlib, not(CONFIG_BUG)))]
122macro_rules! warn_flags {
123    ($file:expr, $flags:expr) => {
124        if false {
125            _ = $file;
126            _ = $flags;
127        }
128    };
129}
130
131#[doc(hidden)]
132pub const fn bugflag_taint(value: u32) -> u32 {
133    value << 8
134}
135
136/// Report a warning if `cond` is true and return the condition's evaluation result.
137#[macro_export]
138macro_rules! warn_on {
139    ($cond:expr) => {{
140        let cond = $cond;
141
142        #[cfg(CONFIG_DEBUG_BUGVERBOSE_DETAILED)]
143        const COND_STR: &str = concat!("[", stringify!($cond), "] ", file!());
144        #[cfg(not(CONFIG_DEBUG_BUGVERBOSE_DETAILED))]
145        const COND_STR: &str = file!();
146
147        if cond {
148            const WARN_ON_FLAGS: u32 = $crate::bug::bugflag_taint($crate::bindings::TAINT_WARN);
149
150            $crate::warn_flags!(COND_STR, WARN_ON_FLAGS);
151        }
152        cond
153    }};
154}
kernel/bug.rs

kernel/
bug.rs
