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Printing facilities. //! //! C header: [`include/linux/printk.h`](../../../../include/linux/printk.h) //! //! Reference: <https://www.kernel.org/doc/html/latest/core-api/printk-basics.html> use core::{ ffi::{c_char, c_void}, fmt, }; use crate::str::RawFormatter; #[cfg(CONFIG_PRINTK)] use crate::bindings; // Called from `vsprintf` with format specifier `%pA`. #[no_mangle] unsafe fn rust_fmt_argument(buf: *mut c_char, end: *mut c_char, ptr: *const c_void) -> *mut c_char { use fmt::Write; // SAFETY: The C contract guarantees that `buf` is valid if it's less than `end`. let mut w = unsafe { RawFormatter::from_ptrs(buf.cast(), end.cast()) }; let _ = w.write_fmt(unsafe { *(ptr as *const fmt::Arguments<'_>) }); w.pos().cast() } /// Format strings. /// /// Public but hidden since it should only be used from public macros. #[doc(hidden)] pub mod format_strings { use crate::bindings; /// The length we copy from the `KERN_*` kernel prefixes. const LENGTH_PREFIX: usize = 2; /// The length of the fixed format strings. pub const LENGTH: usize = 10; /// Generates a fixed format string for the kernel's [`_printk`]. /// /// The format string is always the same for a given level, i.e. for a /// given `prefix`, which are the kernel's `KERN_*` constants. /// /// [`_printk`]: ../../../../include/linux/printk.h const fn generate(is_cont: bool, prefix: &[u8; 3]) -> [u8; LENGTH] { // Ensure the `KERN_*` macros are what we expect. assert!(prefix[0] == b'\x01'); if is_cont { assert!(prefix[1] == b'c'); } else { assert!(prefix[1] >= b'0' && prefix[1] <= b'7'); } assert!(prefix[2] == b'\x00'); let suffix: &[u8; LENGTH - LENGTH_PREFIX] = if is_cont { b"%pA\0\0\0\0\0" } else { b"%s: %pA\0" }; [ prefix[0], prefix[1], suffix[0], suffix[1], suffix[2], suffix[3], suffix[4], suffix[5], suffix[6], suffix[7], ] } // Generate the format strings at compile-time. // // This avoids the compiler generating the contents on the fly in the stack. // // Furthermore, `static` instead of `const` is used to share the strings // for all the kernel. pub static EMERG: [u8; LENGTH] = generate(false, bindings::KERN_EMERG); pub static ALERT: [u8; LENGTH] = generate(false, bindings::KERN_ALERT); pub static CRIT: [u8; LENGTH] = generate(false, bindings::KERN_CRIT); pub static ERR: [u8; LENGTH] = generate(false, bindings::KERN_ERR); pub static WARNING: [u8; LENGTH] = generate(false, bindings::KERN_WARNING); pub static NOTICE: [u8; LENGTH] = generate(false, bindings::KERN_NOTICE); pub static INFO: [u8; LENGTH] = generate(false, bindings::KERN_INFO); pub static DEBUG: [u8; LENGTH] = generate(false, bindings::KERN_DEBUG); pub static CONT: [u8; LENGTH] = generate(true, bindings::KERN_CONT); } /// Prints a message via the kernel's [`_printk`]. /// /// Public but hidden since it should only be used from public macros. /// /// # Safety /// /// The format string must be one of the ones in [`format_strings`], and /// the module name must be null-terminated. /// /// [`_printk`]: ../../../../include/linux/_printk.h #[doc(hidden)] #[cfg_attr(not(CONFIG_PRINTK), allow(unused_variables))] pub unsafe fn call_printk( format_string: &[u8; format_strings::LENGTH], module_name: &[u8], args: fmt::Arguments<'_>, ) { // `_printk` does not seem to fail in any path. #[cfg(CONFIG_PRINTK)] unsafe { bindings::_printk( format_string.as_ptr() as _, module_name.as_ptr(), &args as *const _ as *const c_void, ); } } /// Prints a message via the kernel's [`_printk`] for the `CONT` level. /// /// Public but hidden since it should only be used from public macros. /// /// [`_printk`]: ../../../../include/linux/printk.h #[doc(hidden)] #[cfg_attr(not(CONFIG_PRINTK), allow(unused_variables))] pub fn call_printk_cont(args: fmt::Arguments<'_>) { // `_printk` does not seem to fail in any path. // // SAFETY: The format string is fixed. #[cfg(CONFIG_PRINTK)] unsafe { bindings::_printk( format_strings::CONT.as_ptr() as _, &args as *const _ as *const c_void, ); } } /// Performs formatting and forwards the string to [`call_printk`]. /// /// Public but hidden since it should only be used from public macros. #[doc(hidden)] #[cfg(not(testlib))] #[macro_export] #[allow(clippy::crate_in_macro_def)] macro_rules! print_macro ( // The non-continuation cases (most of them, e.g. `INFO`). ($format_string:path, false, $($arg:tt)+) => ( // To remain sound, `arg`s must be expanded outside the `unsafe` block. // Typically one would use a `let` binding for that; however, `format_args!` // takes borrows on the arguments, but does not extend the scope of temporaries. // Therefore, a `match` expression is used to keep them around, since // the scrutinee is kept until the end of the `match`. match format_args!($($arg)+) { // SAFETY: This hidden macro should only be called by the documented // printing macros which ensure the format string is one of the fixed // ones. All `__LOG_PREFIX`s are null-terminated as they are generated // by the `module!` proc macro or fixed values defined in a kernel // crate. args => unsafe { $crate::print::call_printk( &$format_string, crate::__LOG_PREFIX, args, ); } } ); // The `CONT` case. ($format_string:path, true, $($arg:tt)+) => ( $crate::print::call_printk_cont( format_args!($($arg)+), ); ); ); /// Stub for doctests #[cfg(testlib)] #[macro_export] macro_rules! print_macro ( ($format_string:path, $e:expr, $($arg:tt)+) => ( () ); ); // We could use a macro to generate these macros. However, doing so ends // up being a bit ugly: it requires the dollar token trick to escape `$` as // well as playing with the `doc` attribute. Furthermore, they cannot be easily // imported in the prelude due to [1]. So, for the moment, we just write them // manually, like in the C side; while keeping most of the logic in another // macro, i.e. [`print_macro`]. // // [1]: https://github.com/rust-lang/rust/issues/52234 /// Prints an emergency-level message (level 0). /// /// Use this level if the system is unusable. /// /// Equivalent to the kernel's [`pr_emerg`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_emerg`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_emerg /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_emerg!("hello {}\n", "there"); /// ``` #[macro_export] macro_rules! pr_emerg ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::EMERG, false, $($arg)*) ) ); /// Prints an alert-level message (level 1). /// /// Use this level if action must be taken immediately. /// /// Equivalent to the kernel's [`pr_alert`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_alert`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_alert /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_alert!("hello {}\n", "there"); /// ``` #[macro_export] macro_rules! pr_alert ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::ALERT, false, $($arg)*) ) ); /// Prints a critical-level message (level 2). /// /// Use this level for critical conditions. /// /// Equivalent to the kernel's [`pr_crit`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_crit`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_crit /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_crit!("hello {}\n", "there"); /// ``` #[macro_export] macro_rules! pr_crit ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::CRIT, false, $($arg)*) ) ); /// Prints an error-level message (level 3). /// /// Use this level for error conditions. /// /// Equivalent to the kernel's [`pr_err`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_err`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_err /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_err!("hello {}\n", "there"); /// ``` #[macro_export] macro_rules! pr_err ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::ERR, false, $($arg)*) ) ); /// Prints a warning-level message (level 4). /// /// Use this level for warning conditions. /// /// Equivalent to the kernel's [`pr_warn`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_warn`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_warn /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_warn!("hello {}\n", "there"); /// ``` #[macro_export] macro_rules! pr_warn ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::WARNING, false, $($arg)*) ) ); /// Prints a notice-level message (level 5). /// /// Use this level for normal but significant conditions. /// /// Equivalent to the kernel's [`pr_notice`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_notice`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_notice /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_notice!("hello {}\n", "there"); /// ``` #[macro_export] macro_rules! pr_notice ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::NOTICE, false, $($arg)*) ) ); /// Prints an info-level message (level 6). /// /// Use this level for informational messages. /// /// Equivalent to the kernel's [`pr_info`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_info`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_info /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_info!("hello {}\n", "there"); /// ``` #[macro_export] #[doc(alias = "print")] macro_rules! pr_info ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::INFO, false, $($arg)*) ) ); /// Prints a debug-level message (level 7). /// /// Use this level for debug messages. /// /// Equivalent to the kernel's [`pr_debug`] macro, except that it doesn't support dynamic debug /// yet. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_debug`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_debug /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// pr_debug!("hello {}\n", "there"); /// ``` #[macro_export] #[doc(alias = "print")] macro_rules! pr_debug ( ($($arg:tt)*) => ( if cfg!(debug_assertions) { $crate::print_macro!($crate::print::format_strings::DEBUG, false, $($arg)*) } ) ); /// Continues a previous log message in the same line. /// /// Use only when continuing a previous `pr_*!` macro (e.g. [`pr_info!`]). /// /// Equivalent to the kernel's [`pr_cont`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and /// `alloc::format!` for information about the formatting syntax. /// /// [`pr_cont`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html#c.pr_cont /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html /// /// # Examples /// /// ``` /// # use kernel::pr_cont; /// pr_info!("hello"); /// pr_cont!(" {}\n", "there"); /// ``` #[macro_export] macro_rules! pr_cont ( ($($arg:tt)*) => ( $crate::print_macro!($crate::print::format_strings::CONT, true, $($arg)*) ) ); |