[PATCH v2 03/28] rust: print: add `pr_cont!` macro

ojeda
2022-12-02T16:15:37Z

From: Miguel Ojeda <ojeda@kernel.org>

This level is a bit different from the rest since it does not
pass the module name to the `_printk()` call.

Thus add a new parameter to the general `print_macro!` to
handle it differently.

Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Sergio González Collado <sergio.collado@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
rust/kernel/print.rs | 72 ++++++++++++++++++++++++++++++++++++++------
1 file changed, 63 insertions(+), 9 deletions(-)

diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs
index 694f51c6da5c..29bf9c2e8aee 100644
--- a/rust/kernel/print.rs
+++ b/rust/kernel/print.rs
@@ -81,6 +81,7 @@ pub mod format_strings {
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`].
@@ -111,6 +112,26 @@ pub unsafe fn call_printk(
}
}

+/// 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.
@@ -120,7 +141,7 @@ pub unsafe fn call_printk(
#[allow(clippy::crate_in_macro_def)]
macro_rules! print_macro (
// The non-continuation cases (most of them, e.g. `INFO`).
- ($format_string:path, $($arg:tt)+) => (
+ ($format_string:path, false, $($arg:tt)+) => (
// 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
@@ -134,6 +155,13 @@ macro_rules! print_macro (
);
}
);
+
+ // The `CONT` case.
+ ($format_string:path, true, $($arg:tt)+) => (
+ $crate::print::call_printk_cont(
+ format_args!($($arg)+),
+ );
+ );
);

/// Stub for doctests
@@ -174,7 +202,7 @@ macro_rules! print_macro (
#[macro_export]
macro_rules! pr_emerg (
($($arg:tt)*) => (
- $crate::print_macro!($crate::print::format_strings::EMERG, $($arg)*)
+ $crate::print_macro!($crate::print::format_strings::EMERG, false, $($arg)*)
)
);

@@ -198,7 +226,7 @@ macro_rules! pr_emerg (
#[macro_export]
macro_rules! pr_alert (
($($arg:tt)*) => (
- $crate::print_macro!($crate::print::format_strings::ALERT, $($arg)*)
+ $crate::print_macro!($crate::print::format_strings::ALERT, false, $($arg)*)
)
);

@@ -222,7 +250,7 @@ macro_rules! pr_alert (
#[macro_export]
macro_rules! pr_crit (
($($arg:tt)*) => (
- $crate::print_macro!($crate::print::format_strings::CRIT, $($arg)*)
+ $crate::print_macro!($crate::print::format_strings::CRIT, false, $($arg)*)
)
);

@@ -246,7 +274,7 @@ macro_rules! pr_crit (
#[macro_export]
macro_rules! pr_err (
($($arg:tt)*) => (
- $crate::print_macro!($crate::print::format_strings::ERR, $($arg)*)
+ $crate::print_macro!($crate::print::format_strings::ERR, false, $($arg)*)
)
);

@@ -270,7 +298,7 @@ macro_rules! pr_err (
#[macro_export]
macro_rules! pr_warn (
($($arg:tt)*) => (
- $crate::print_macro!($crate::print::format_strings::WARNING, $($arg)*)
+ $crate::print_macro!($crate::print::format_strings::WARNING, false, $($arg)*)
)
);

@@ -294,7 +322,7 @@ macro_rules! pr_warn (
#[macro_export]
macro_rules! pr_notice (
($($arg:tt)*) => (
- $crate::print_macro!($crate::print::format_strings::NOTICE, $($arg)*)
+ $crate::print_macro!($crate::print::format_strings::NOTICE, false, $($arg)*)
)
);

@@ -319,7 +347,7 @@ macro_rules! pr_notice (
#[doc(alias = "print")]
macro_rules! pr_info (
($($arg:tt)*) => (
- $crate::print_macro!($crate::print::format_strings::INFO, $($arg)*)
+ $crate::print_macro!($crate::print::format_strings::INFO, false, $($arg)*)
)
);

@@ -346,7 +374,33 @@ macro_rules! pr_info (
macro_rules! pr_debug (
($($arg:tt)*) => (
if cfg!(debug_assertions) {
- $crate::print_macro!($crate::print::format_strings::DEBUG, $($arg)*)
+ $crate::print_macro!($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)*)
+ )
+);
--
2.38.1