Introduce a `fmt!` macro which wraps all arguments in `kernel::fmt::Adapter` and a `kernel::fmt::Display` trait. This enables formatting of foreign types (like `core::ffi::CStr`) that do not implement `core::fmt::Display` due to concerns around lossy conversions which do not apply in the kernel.
Replace all direct calls to `format_args!` with `fmt!`.
Replace all implementations of `core::fmt::Display` with implementations of `kernel::fmt::Display`.
Suggested-by: Alice Ryhl aliceryhl@google.com Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Cu... Acked-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Reviewed-by: Alice Ryhl aliceryhl@google.com Signed-off-by: Tamir Duberstein tamird@gmail.com --- drivers/block/rnull.rs | 2 +- drivers/gpu/nova-core/gpu.rs | 4 +- rust/kernel/block/mq.rs | 2 +- rust/kernel/device.rs | 2 +- rust/kernel/fmt.rs | 89 +++++++++++++++++++++++++++++++++++++++ rust/kernel/kunit.rs | 6 +-- rust/kernel/lib.rs | 1 + rust/kernel/prelude.rs | 3 +- rust/kernel/print.rs | 4 +- rust/kernel/seq_file.rs | 2 +- rust/kernel/str.rs | 22 ++++------ rust/macros/fmt.rs | 99 ++++++++++++++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 19 +++++++++ rust/macros/quote.rs | 7 ++++ scripts/rustdoc_test_gen.rs | 2 +- 15 files changed, 236 insertions(+), 28 deletions(-)
diff --git a/drivers/block/rnull.rs b/drivers/block/rnull.rs index d07e76ae2c13..6366da12c5a5 100644 --- a/drivers/block/rnull.rs +++ b/drivers/block/rnull.rs @@ -51,7 +51,7 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> { .logical_block_size(4096)? .physical_block_size(4096)? .rotational(false) - .build(format_args!("rnullb{}", 0), tagset) + .build(fmt!("rnullb{}", 0), tagset) })();
try_pin_init!(Self { diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs index 60b86f370284..e6b208175ff9 100644 --- a/drivers/gpu/nova-core/gpu.rs +++ b/drivers/gpu/nova-core/gpu.rs @@ -91,7 +91,7 @@ pub(crate) fn arch(&self) -> Architecture { // Hence, replace with something like strum_macros derive(Display). // // For now, redirect to fmt::Debug for convenience. -impl fmt::Display for Chipset { +impl kernel::fmt::Display for Chipset { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "{self:?}") } @@ -132,7 +132,7 @@ fn from_boot0(boot0: regs::NV_PMC_BOOT_0) -> Self { } }
-impl fmt::Display for Revision { +impl kernel::fmt::Display for Revision { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "{:x}.{:x}", self.major, self.minor) } diff --git a/rust/kernel/block/mq.rs b/rust/kernel/block/mq.rs index 831445d37181..61ea35bba7d5 100644 --- a/rust/kernel/block/mq.rs +++ b/rust/kernel/block/mq.rs @@ -82,7 +82,7 @@ //! Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?; //! let mut disk = gen_disk::GenDiskBuilder::new() //! .capacity_sectors(4096) -//! .build(format_args!("myblk"), tagset)?; +//! .build(fmt!("myblk"), tagset)?; //! //! # Ok::<(), kernel::error::Error>(()) //! ``` diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 5c946af3a4d5..86b945576780 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -345,7 +345,7 @@ macro_rules! impl_device_context_into_aref { macro_rules! dev_printk { ($method:ident, $dev:expr, $($f:tt)*) => { { - ($dev).$method(::core::format_args!($($f)*)); + ($dev).$method($crate::prelude::fmt!($($f)*)); } } } diff --git a/rust/kernel/fmt.rs b/rust/kernel/fmt.rs new file mode 100644 index 000000000000..348d16987de6 --- /dev/null +++ b/rust/kernel/fmt.rs @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Formatting utilities. + +use core::fmt; + +/// Internal adapter used to route allow implementations of formatting traits for foreign types. +/// +/// It is inserted automatically by the [`fmt!`] macro and is not meant to be used directly. +/// +/// [`fmt!`]: crate::prelude::fmt! +#[doc(hidden)] +pub struct Adapter<T>(pub T); + +macro_rules! impl_fmt_adapter_forward { + ($($trait:ident),* $(,)?) => { + $( + impl<T: fmt::$trait> fmt::$trait for Adapter<T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let Self(t) = self; + fmt::$trait::fmt(t, f) + } + } + )* + }; +} + +impl_fmt_adapter_forward!(Debug, LowerHex, UpperHex, Octal, Binary, Pointer, LowerExp, UpperExp); + +/// A copy of [`fmt::Display`] that allows us to implement it for foreign types. +/// +/// Types should implement this trait rather than [`fmt::Display`]. Together with the [`Adapter`] +/// type and [`fmt!`] macro, it allows for formatting foreign types (e.g. types from core) which do +/// not implement [`fmt::Display`] directly. +/// +/// [`fmt!`]: crate::prelude::fmt! +pub trait Display { + /// Same as [`fmt::Display::fmt`]. + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result; +} + +impl<T: ?Sized + Display> Display for &T { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + Display::fmt(*self, f) + } +} + +impl<T: ?Sized + Display> fmt::Display for Adapter<&T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let Self(t) = self; + Display::fmt(t, f) + } +} + +macro_rules! impl_display_forward { + ($( + $( { $($generics:tt)* } )? $ty:ty $( { where $($where:tt)* } )? + ),* $(,)?) => { + $( + impl$($($generics)*)? Display for $ty $(where $($where)*)? { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self, f) + } + } + )* + }; +} + +impl_display_forward!( + bool, + char, + core::panic::PanicInfo<'_>, + fmt::Arguments<'_>, + i128, + i16, + i32, + i64, + i8, + isize, + str, + u128, + u16, + u32, + u64, + u8, + usize, + {<T: ?Sized>} crate::sync::Arc<T> {where crate::sync::Arc<T>: fmt::Display}, + {<T: ?Sized>} crate::sync::UniqueArc<T> {where crate::sync::UniqueArc<T>: fmt::Display}, +); diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 099a61bbb8f4..3539edbceaf5 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -74,14 +74,14 @@ macro_rules! kunit_assert { // mistake (it is hidden to prevent that). // // This mimics KUnit's failed assertion format. - $crate::kunit::err(format_args!( + $crate::kunit::err($crate::prelude::fmt!( " # {}: ASSERTION FAILED at {FILE}:{LINE}\n", $name )); - $crate::kunit::err(format_args!( + $crate::kunit::err($crate::prelude::fmt!( " Expected {CONDITION} to be true, but is false\n" )); - $crate::kunit::err(format_args!( + $crate::kunit::err($crate::prelude::fmt!( " Failure not reported to KUnit since this is a non-KUnit task\n" )); break 'out; diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 6b4774b2b1c3..aadcfaa5c759 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -77,6 +77,7 @@ pub mod faux; #[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)] pub mod firmware; +pub mod fmt; pub mod fs; pub mod init; pub mod io; diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index 2f30a398dddd..41cebd906c4c 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -22,7 +22,7 @@ pub use crate::alloc::{flags::*, Box, KBox, KVBox, KVVec, KVec, VBox, VVec, Vec};
#[doc(no_inline)] -pub use macros::{export, kunit_tests, module, vtable}; +pub use macros::{export, fmt, kunit_tests, module, vtable};
pub use pin_init::{init, pin_data, pin_init, pinned_drop, InPlaceWrite, Init, PinInit, Zeroable};
@@ -31,7 +31,6 @@ // `super::std_vendor` is hidden, which makes the macro inline for some reason. #[doc(no_inline)] pub use super::dbg; -pub use super::fmt; pub use super::{dev_alert, dev_crit, dev_dbg, dev_emerg, dev_err, dev_info, dev_notice, dev_warn}; pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs index ecdcee43e5a5..d9c619edcd2f 100644 --- a/rust/kernel/print.rs +++ b/rust/kernel/print.rs @@ -149,7 +149,7 @@ macro_rules! print_macro ( // 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)+) { + match $crate::prelude::fmt!($($arg)+) { // SAFETY: This hidden macro should only be called by the documented // printing macros which ensure the format string is one of the fixed // ones. All `__LOG_PREFIX`s are null-terminated as they are generated @@ -168,7 +168,7 @@ macro_rules! print_macro ( // The `CONT` case. ($format_string:path, true, $($arg:tt)+) => ( $crate::print::call_printk_cont( - format_args!($($arg)+), + $crate::prelude::fmt!($($arg)+), ); ); ); diff --git a/rust/kernel/seq_file.rs b/rust/kernel/seq_file.rs index 8f199b1a3bb1..05c9b7bec727 100644 --- a/rust/kernel/seq_file.rs +++ b/rust/kernel/seq_file.rs @@ -47,7 +47,7 @@ pub fn call_printf(&self, args: core::fmt::Arguments<'_>) { #[macro_export] macro_rules! seq_print { ($m:expr, $($arg:tt)+) => ( - $m.call_printf(format_args!($($arg)+)) + $m.call_printf($crate::prelude::fmt!($($arg)+)) ); } pub use seq_print; diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index cbc8b459ed41..d3fa4b703d35 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -50,11 +50,11 @@ pub fn strip_prefix(&self, pattern: impl AsRef<Self>) -> Option<&BStr> { } }
-impl fmt::Display for BStr { +impl crate::fmt::Display for BStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` - /// # use kernel::{fmt, b_str, str::{BStr, CString}}; + /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// let ascii = b_str!("Hello, BStr!"); /// let s = CString::try_from_fmt(fmt!("{}", ascii))?; /// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes()); @@ -85,7 +85,7 @@ impl fmt::Debug for BStr { /// escaping the rest. /// /// ``` - /// # use kernel::{fmt, b_str, str::{BStr, CString}}; + /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// // Embedded double quotes are escaped. /// let ascii = b_str!("Hello, "BStr"!"); /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?; @@ -424,12 +424,12 @@ pub fn to_ascii_uppercase(&self) -> Result<CString, AllocError> { } }
-impl fmt::Display for CStr { +impl crate::fmt::Display for CStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::c_str; - /// # use kernel::fmt; + /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("🐧"); @@ -459,7 +459,7 @@ impl fmt::Debug for CStr { /// /// ``` /// # use kernel::c_str; - /// # use kernel::fmt; + /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("🐧"); @@ -578,7 +578,7 @@ mod tests {
macro_rules! format { ($($f:tt)*) => ({ - CString::try_from_fmt(::kernel::fmt!($($f)*))?.to_str()? + CString::try_from_fmt(crate::prelude::fmt!($($f)*))?.to_str()? }) }
@@ -840,7 +840,7 @@ fn write_str(&mut self, s: &str) -> fmt::Result { /// # Examples /// /// ``` -/// use kernel::{str::CString, fmt}; +/// use kernel::{str::CString, prelude::fmt}; /// /// let s = CString::try_from_fmt(fmt!("{}{}{}", "abc", 10, 20))?; /// assert_eq!(s.as_bytes_with_nul(), "abc1020\0".as_bytes()); @@ -930,9 +930,3 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&**self, f) } } - -/// A convenience alias for [`core::format_args`]. -#[macro_export] -macro_rules! fmt { - ($($f:tt)*) => ( ::core::format_args!($($f)*) ) -} diff --git a/rust/macros/fmt.rs b/rust/macros/fmt.rs new file mode 100644 index 000000000000..edc37c220a89 --- /dev/null +++ b/rust/macros/fmt.rs @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0 + +use proc_macro::{Ident, TokenStream, TokenTree}; +use std::collections::BTreeSet; + +/// Please see [`crate::fmt`] for documentation. +pub(crate) fn fmt(input: TokenStream) -> TokenStream { + let mut input = input.into_iter(); + + let first_opt = input.next(); + let first_owned_str; + let mut names = BTreeSet::new(); + let first_lit = { + let Some((mut first_str, first_lit)) = (match first_opt.as_ref() { + Some(TokenTree::Literal(first_lit)) => { + first_owned_str = first_lit.to_string(); + Some(first_owned_str.as_str()).and_then(|first| { + let first = first.strip_prefix('"')?; + let first = first.strip_suffix('"')?; + Some((first, first_lit)) + }) + } + _ => None, + }) else { + return first_opt.into_iter().chain(input).collect(); + }; + while let Some((_, rest)) = first_str.split_once('{') { + first_str = rest; + if let Some(rest) = first_str.strip_prefix('{') { + first_str = rest; + continue; + } + if let Some((name, rest)) = first_str.split_once('}') { + first_str = rest; + let name = name.split_once(':').map_or(name, |(name, _)| name); + if !name.is_empty() && !name.chars().all(|c| c.is_ascii_digit()) { + names.insert(name); + } + } + } + first_lit + }; + + let first_span = first_lit.span(); + let adapter = quote_spanned! { + first_span => ::kernel::fmt::Adapter + }; + + let mut args = TokenStream::from_iter(first_opt); + { + let mut flush = |args: &mut TokenStream, current: &mut TokenStream| { + let current = std::mem::take(current); + if !current.is_empty() { + let (lhs, rhs) = (|| { + let mut current = current.into_iter(); + let mut acc = TokenStream::new(); + while let Some(tt) = current.next() { + // Split on `=` only once to handle cases like `a = b = c`. + if matches!(&tt, TokenTree::Punct(p) if p.as_char() == '=') { + names.remove(acc.to_string().as_str()); + // Include the `=` itself to keep the handling below uniform. + acc.extend([tt]); + return (Some(acc), current.collect::<TokenStream>()); + } + acc.extend([tt]); + } + (None, acc) + })(); + args.extend(quote_spanned! { + first_span => #lhs #adapter(&#rhs) + }); + } + }; + + let mut current = TokenStream::new(); + for tt in input { + match &tt { + TokenTree::Punct(p) if p.as_char() == ',' => { + flush(&mut args, &mut current); + &mut args + } + _ => &mut current, + } + .extend([tt]); + } + flush(&mut args, &mut current); + } + + for name in names { + let name = Ident::new(name, first_span); + args.extend(quote_spanned! { + first_span => , #name = #adapter(&#name) + }); + } + + quote_spanned! { + first_span => ::core::format_args!(#args) + } +} diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index fa847cf3a9b5..980e70d253e4 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -15,6 +15,7 @@ mod quote; mod concat_idents; mod export; +mod fmt; mod helpers; mod kunit; mod module; @@ -201,6 +202,24 @@ pub fn export(attr: TokenStream, ts: TokenStream) -> TokenStream { export::export(attr, ts) }
+/// Like [`core::format_args!`], but automatically wraps arguments in [`kernel::fmt::Adapter`]. +/// +/// This macro allows generating `core::fmt::Arguments` while ensuring that each argument is wrapped +/// with `::kernel::fmt::Adapter`, which customizes formatting behavior for kernel logging. +/// +/// Named arguments used in the format string (e.g. `{foo}`) are detected and resolved from local +/// bindings. All positional and named arguments are automatically wrapped. +/// +/// This macro is an implementation detail of other kernel logging macros like [`pr_info!`] and +/// should not typically be used directly. +/// +/// [`kernel::fmt::Adapter`]: ../kernel/fmt/struct.Adapter.html +/// [`pr_info!`]: ../kernel/macro.pr_info.html +#[proc_macro] +pub fn fmt(input: TokenStream) -> TokenStream { + fmt::fmt(input) +} + /// Concatenate two identifiers. /// /// This is useful in macros that need to declare or reference items with names diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs index acc140c18653..ddfc21577539 100644 --- a/rust/macros/quote.rs +++ b/rust/macros/quote.rs @@ -48,6 +48,7 @@ macro_rules! quote_spanned { ($span:expr => $($tt:tt)*) => {{ let mut tokens = ::proc_macro::TokenStream::new(); { + #[allow(unused_variables)] let span = $span; quote_spanned!(@proc tokens span $($tt)*); } @@ -146,6 +147,12 @@ macro_rules! quote_spanned { )]); quote_spanned!(@proc $v $span $($tt)*); }; + (@proc $v:ident $span:ident & $($tt:tt)*) => { + $v.extend([::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new('&', ::proc_macro::Spacing::Alone), + )]); + quote_spanned!(@proc $v $span $($tt)*); + }; (@proc $v:ident $span:ident _ $($tt:tt)*) => { $v.extend([::proc_macro::TokenTree::Ident( ::proc_macro::Ident::new("_", $span), diff --git a/scripts/rustdoc_test_gen.rs b/scripts/rustdoc_test_gen.rs index 1ca253594d38..507d36875196 100644 --- a/scripts/rustdoc_test_gen.rs +++ b/scripts/rustdoc_test_gen.rs @@ -201,7 +201,7 @@ macro_rules! assert_eq {{ // This follows the syntax for declaring test metadata in the proposed KTAP v2 spec, which may // be used for the proposed KUnit test attributes API. Thus hopefully this will make migration // easier later on. - ::kernel::kunit::info(format_args!(" # {kunit_name}.location: {real_path}:{line}\n")); + ::kernel::kunit::info(fmt!(" # {kunit_name}.location: {real_path}:{line}\n"));
/// The anchor where the test code body starts. #[allow(unused)]