Merge tag 'rust-6.2' of https://github.com/Rust-for-Linux/linux

Pull rust updates from Miguel Ojeda:
 "The first set of changes after the merge, the major ones being:

   - String and formatting: new types 'CString', 'CStr', 'BStr' and
     'Formatter'; new macros 'c_str!', 'b_str!' and 'fmt!'.

   - Errors: the rest of the error codes from 'errno-base.h', as well as
     some 'From' trait implementations for the 'Error' type.

   - Printing: the rest of the 'pr_*!' levels and the continuation one
     'pr_cont!', as well as a new sample.

   - 'alloc' crate: new constructors 'try_with_capacity()' and
     'try_with_capacity_in()' for 'RawVec' and 'Vec'.

   - Procedural macros: new macros '#[vtable]' and 'concat_idents!', as
     well as better ergonomics for 'module!' users.

   - Asserting: new macros 'static_assert!', 'build_error!' and
     'build_assert!', as well as a new crate 'build_error' to support
     them.

   - Vocabulary types: new types 'Opaque' and 'Either'.

   - Debugging: new macro 'dbg!'"

* tag 'rust-6.2' of https://github.com/Rust-for-Linux/linux: (28 commits)
  rust: types: add `Opaque` type
  rust: types: add `Either` type
  rust: build_assert: add `build_{error,assert}!` macros
  rust: add `build_error` crate
  rust: static_assert: add `static_assert!` macro
  rust: std_vendor: add `dbg!` macro based on `std`'s one
  rust: str: add `fmt!` macro
  rust: str: add `CString` type
  rust: str: add `Formatter` type
  rust: str: add `c_str!` macro
  rust: str: add `CStr` unit tests
  rust: str: implement several traits for `CStr`
  rust: str: add `CStr` type
  rust: str: add `b_str!` macro
  rust: str: add `BStr` type
  rust: alloc: add `Vec::try_with_capacity{,_in}()` constructors
  rust: alloc: add `RawVec::try_with_capacity_in()` constructor
  rust: prelude: add `error::code::*` constant items
  rust: error: add `From` implementations for `Error`
  rust: error: add codes from `errno-base.h`
  ...

lib/Kconfig.debug

@@ -2823,6 +2823,22 @@ config RUST_OVERFLOW_CHECKS
 
 	  If unsure, say Y.
 
+config RUST_BUILD_ASSERT_ALLOW
+	bool "Allow unoptimized build-time assertions"
+	depends on RUST
+	help
+	  Controls how are `build_error!` and `build_assert!` handled during build.
+
+	  If calls to them exist in the binary, it may indicate a violated invariant
+	  or that the optimizer failed to verify the invariant during compilation.
+
+	  This should not happen, thus by default the build is aborted. However,
+	  as an escape hatch, you can choose Y here to ignore them during build
+	  and let the check be carried at runtime (with `panic!` being called if
+	  the check fails).
+
+	  If unsure, say N.
+
 endmenu # "Rust"
 
 source "Documentation/Kconfig"

rust/Makefile

@@ -19,6 +19,12 @@ obj-$(CONFIG_RUST) += alloc.o bindings.o kernel.o
 always-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \
     exports_kernel_generated.h
 
+ifdef CONFIG_RUST_BUILD_ASSERT_ALLOW
+obj-$(CONFIG_RUST) += build_error.o
+else
+always-$(CONFIG_RUST) += build_error.o
+endif
+
 obj-$(CONFIG_RUST) += exports.o
 
 # Avoids running `$(RUSTC)` for the sysroot when it may not be available.
@@ -108,7 +114,7 @@ rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
 	$(call if_changed,rustdoc)
 
 rustdoc-kernel: private rustc_target_flags = --extern alloc \
-    --extern macros=$(objtree)/$(obj)/libmacros.so \
+    --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \
     --extern bindings
 rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
     rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \
@@ -126,6 +132,9 @@ quiet_cmd_rustc_test_library = RUSTC TL $<
 		-L$(objtree)/$(obj)/test \
 		--crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $<
 
+rusttestlib-build_error: $(src)/build_error.rs rusttest-prepare FORCE
+	$(call if_changed,rustc_test_library)
+
 rusttestlib-macros: private rustc_target_flags = --extern proc_macro
 rusttestlib-macros: private rustc_test_library_proc = yes
 rusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
@@ -216,9 +225,9 @@ rusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
 	$(call if_changed,rustdoc_test)
 
 rusttest-kernel: private rustc_target_flags = --extern alloc \
-    --extern macros --extern bindings
+    --extern build_error --extern macros --extern bindings
 rusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \
-    rusttestlib-macros rusttestlib-bindings FORCE
+    rusttestlib-build_error rusttestlib-macros rusttestlib-bindings FORCE
 	$(call if_changed,rustc_test)
 	$(call if_changed,rustc_test_library)
 
@@ -366,6 +375,9 @@ $(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
 $(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE
 	$(call if_changed_dep,rustc_library)
 
+$(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
+	$(call if_changed_dep,rustc_library)
+
 $(obj)/bindings.o: $(src)/bindings/lib.rs \
     $(obj)/compiler_builtins.o \
     $(obj)/bindings/bindings_generated.rs \
@@ -373,8 +385,8 @@ $(obj)/bindings.o: $(src)/bindings/lib.rs \
 	$(call if_changed_dep,rustc_library)
 
 $(obj)/kernel.o: private rustc_target_flags = --extern alloc \
-    --extern macros --extern bindings
-$(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o \
+    --extern build_error --extern macros --extern bindings
+$(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
     $(obj)/libmacros.so $(obj)/bindings.o FORCE
 	$(call if_changed_dep,rustc_library)
 

rust/alloc/raw_vec.rs

@@ -20,11 +20,11 @@ use crate::collections::TryReserveErrorKind::*;
 #[cfg(test)]
 mod tests;
 
-#[cfg(not(no_global_oom_handling))]
 enum AllocInit {
     /// The contents of the new memory are uninitialized.
     Uninitialized,
     /// The new memory is guaranteed to be zeroed.
+    #[allow(dead_code)]
     Zeroed,
 }
 
@@ -133,6 +133,13 @@ impl<T, A: Allocator> RawVec<T, A> {
         Self::allocate_in(capacity, AllocInit::Uninitialized, alloc)
     }
 
+    /// Like `try_with_capacity`, but parameterized over the choice of
+    /// allocator for the returned `RawVec`.
+    #[inline]
+    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
+        Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc)
+    }
+
     /// Like `with_capacity_zeroed`, but parameterized over the choice
     /// of allocator for the returned `RawVec`.
     #[cfg(not(no_global_oom_handling))]
@@ -203,6 +210,30 @@ impl<T, A: Allocator> RawVec<T, A> {
         }
     }
 
+    fn try_allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Result<Self, TryReserveError> {
+        // Don't allocate here because `Drop` will not deallocate when `capacity` is 0.
+        if mem::size_of::<T>() == 0 || capacity == 0 {
+            return Ok(Self::new_in(alloc));
+        }
+
+        let layout = Layout::array::<T>(capacity).map_err(|_| CapacityOverflow)?;
+        alloc_guard(layout.size())?;
+        let result = match init {
+            AllocInit::Uninitialized => alloc.allocate(layout),
+            AllocInit::Zeroed => alloc.allocate_zeroed(layout),
+        };
+        let ptr = result.map_err(|_| AllocError { layout, non_exhaustive: () })?;
+
+        // Allocators currently return a `NonNull<[u8]>` whose length
+        // matches the size requested. If that ever changes, the capacity
+        // here should change to `ptr.len() / mem::size_of::<T>()`.
+        Ok(Self {
+            ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
+            cap: capacity,
+            alloc,
+        })
+    }
+
     /// Reconstitutes a `RawVec` from a pointer, capacity, and allocator.
     ///
     /// # Safety

rust/alloc/vec/mod.rs

@@ -472,6 +472,48 @@ impl<T> Vec<T> {
         Self::with_capacity_in(capacity, Global)
     }
 
+    /// Tries to construct a new, empty `Vec<T>` with the specified capacity.
+    ///
+    /// The vector will be able to hold exactly `capacity` elements without
+    /// reallocating. If `capacity` is 0, the vector will not allocate.
+    ///
+    /// It is important to note that although the returned vector has the
+    /// *capacity* specified, the vector will have a zero *length*. For an
+    /// explanation of the difference between length and capacity, see
+    /// *[Capacity and reallocation]*.
+    ///
+    /// [Capacity and reallocation]: #capacity-and-reallocation
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = Vec::try_with_capacity(10).unwrap();
+    ///
+    /// // The vector contains no items, even though it has capacity for more
+    /// assert_eq!(vec.len(), 0);
+    /// assert_eq!(vec.capacity(), 10);
+    ///
+    /// // These are all done without reallocating...
+    /// for i in 0..10 {
+    ///     vec.push(i);
+    /// }
+    /// assert_eq!(vec.len(), 10);
+    /// assert_eq!(vec.capacity(), 10);
+    ///
+    /// // ...but this may make the vector reallocate
+    /// vec.push(11);
+    /// assert_eq!(vec.len(), 11);
+    /// assert!(vec.capacity() >= 11);
+    ///
+    /// let mut result = Vec::try_with_capacity(usize::MAX);
+    /// assert!(result.is_err());
+    /// ```
+    #[inline]
+    #[stable(feature = "kernel", since = "1.0.0")]
+    pub fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> {
+        Self::try_with_capacity_in(capacity, Global)
+    }
+
     /// Creates a `Vec<T>` directly from the raw components of another vector.
     ///
     /// # Safety
@@ -617,6 +659,53 @@ impl<T, A: Allocator> Vec<T, A> {
         Vec { buf: RawVec::with_capacity_in(capacity, alloc), len: 0 }
     }
 
+    /// Tries to construct a new, empty `Vec<T, A>` with the specified capacity
+    /// with the provided allocator.
+    ///
+    /// The vector will be able to hold exactly `capacity` elements without
+    /// reallocating. If `capacity` is 0, the vector will not allocate.
+    ///
+    /// It is important to note that although the returned vector has the
+    /// *capacity* specified, the vector will have a zero *length*. For an
+    /// explanation of the difference between length and capacity, see
+    /// *[Capacity and reallocation]*.
+    ///
+    /// [Capacity and reallocation]: #capacity-and-reallocation
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(allocator_api)]
+    ///
+    /// use std::alloc::System;
+    ///
+    /// let mut vec = Vec::try_with_capacity_in(10, System).unwrap();
+    ///
+    /// // The vector contains no items, even though it has capacity for more
+    /// assert_eq!(vec.len(), 0);
+    /// assert_eq!(vec.capacity(), 10);
+    ///
+    /// // These are all done without reallocating...
+    /// for i in 0..10 {
+    ///     vec.push(i);
+    /// }
+    /// assert_eq!(vec.len(), 10);
+    /// assert_eq!(vec.capacity(), 10);
+    ///
+    /// // ...but this may make the vector reallocate
+    /// vec.push(11);
+    /// assert_eq!(vec.len(), 11);
+    /// assert!(vec.capacity() >= 11);
+    ///
+    /// let mut result = Vec::try_with_capacity_in(usize::MAX, System);
+    /// assert!(result.is_err());
+    /// ```
+    #[inline]
+    #[stable(feature = "kernel", since = "1.0.0")]
+    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
+        Ok(Vec { buf: RawVec::try_with_capacity_in(capacity, alloc)?, len: 0 })
+    }
+
     /// Creates a `Vec<T, A>` directly from the raw components of another vector.
     ///
     /// # Safety

rust/build_error.rs

+// SPDX-License-Identifier: GPL-2.0
+
+//! Build-time error.
+//!
+//! This crate provides a [const function][const-functions] `build_error`, which will panic in
+//! compile-time if executed in [const context][const-context], and will cause a build error
+//! if not executed at compile time and the optimizer does not optimise away the call.
+//!
+//! It is used by `build_assert!` in the kernel crate, allowing checking of
+//! conditions that could be checked statically, but could not be enforced in
+//! Rust yet (e.g. perform some checks in [const functions][const-functions], but those
+//! functions could still be called in the runtime).
+//!
+//! For details on constant evaluation in Rust, please see the [Reference][const-eval].
+//!
+//! [const-eval]: https://doc.rust-lang.org/reference/const_eval.html
+//! [const-functions]: https://doc.rust-lang.org/reference/const_eval.html#const-functions
+//! [const-context]: https://doc.rust-lang.org/reference/const_eval.html#const-context
+
+#![no_std]
+
+/// Panics if executed in [const context][const-context], or triggers a build error if not.
+///
+/// [const-context]: https://doc.rust-lang.org/reference/const_eval.html#const-context
+#[inline(never)]
+#[cold]
+#[export_name = "rust_build_error"]
+#[track_caller]
+pub const fn build_error(msg: &'static str) -> ! {
+    panic!("{}", msg);
+}

rust/exports.c

@@ -19,3 +19,8 @@
 #include "exports_alloc_generated.h"
 #include "exports_bindings_generated.h"
 #include "exports_kernel_generated.h"
+
+// For modules using `rust/build_error.rs`.
+#ifdef CONFIG_RUST_BUILD_ASSERT_ALLOW
+EXPORT_SYMBOL_RUST_GPL(rust_build_error);
+#endif

rust/kernel/build_assert.rs

+// SPDX-License-Identifier: GPL-2.0
+
+//! Build-time assert.
+
+/// Fails the build if the code path calling `build_error!` can possibly be executed.
+///
+/// If the macro is executed in const context, `build_error!` will panic.
+/// If the compiler or optimizer cannot guarantee that `build_error!` can never
+/// be called, a build error will be triggered.
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::build_error;
+/// #[inline]
+/// fn foo(a: usize) -> usize {
+///     a.checked_add(1).unwrap_or_else(|| build_error!("overflow"))
+/// }
+///
+/// assert_eq!(foo(usize::MAX - 1), usize::MAX); // OK.
+/// // foo(usize::MAX); // Fails to compile.
+/// ```
+#[macro_export]
+macro_rules! build_error {
+    () => {{
+        $crate::build_error("")
+    }};
+    ($msg:expr) => {{
+        $crate::build_error($msg)
+    }};
+}
+
+/// Asserts that a boolean expression is `true` at compile time.
+///
+/// If the condition is evaluated to `false` in const context, `build_assert!`
+/// will panic. If the compiler or optimizer cannot guarantee the condition will
+/// be evaluated to `true`, a build error will be triggered.
+///
+/// [`static_assert!`] should be preferred to `build_assert!` whenever possible.
+///
+/// # Examples
+///
+/// These examples show that different types of [`assert!`] will trigger errors
+/// at different stage of compilation. It is preferred to err as early as
+/// possible, so [`static_assert!`] should be used whenever possible.
+/// ```ignore
+/// fn foo() {
+///     static_assert!(1 > 1); // Compile-time error
+///     build_assert!(1 > 1); // Build-time error
+///     assert!(1 > 1); // Run-time error
+/// }
+/// ```
+///
+/// When the condition refers to generic parameters or parameters of an inline function,
+/// [`static_assert!`] cannot be used. Use `build_assert!` in this scenario.
+/// ```
+/// fn foo<const N: usize>() {
+///     // `static_assert!(N > 1);` is not allowed
+///     build_assert!(N > 1); // Build-time check
+///     assert!(N > 1); // Run-time check
+/// }
+///
+/// #[inline]
+/// fn bar(n: usize) {
+///     // `static_assert!(n > 1);` is not allowed
+///     build_assert!(n > 1); // Build-time check
+///     assert!(n > 1); // Run-time check
+/// }
+/// ```
+#[macro_export]
+macro_rules! build_assert {
+    ($cond:expr $(,)?) => {{
+        if !$cond {
+            $crate::build_error(concat!("assertion failed: ", stringify!($cond)));
+        }
+    }};
+    ($cond:expr, $msg:expr) => {{
+        if !$cond {
+            $crate::build_error($msg);
+        }
+    }};
+}

rust/kernel/error.rs

@@ -4,12 +4,60 @@
 //!
 //! C header: [`include/uapi/asm-generic/errno-base.h`](../../../include/uapi/asm-generic/errno-base.h)
 
-use alloc::collections::TryReserveError;
+use alloc::{
+    alloc::{AllocError, LayoutError},
+    collections::TryReserveError,
+};
+
+use core::convert::From;
+use core::num::TryFromIntError;
+use core::str::Utf8Error;
 
 /// Contains the C-compatible error codes.
 pub mod code {
-    /// Out of memory.
-    pub const ENOMEM: super::Error = super::Error(-(crate::bindings::ENOMEM as i32));
+    macro_rules! declare_err {
+        ($err:tt $(,)? $($doc:expr),+) => {
+            $(
+            #[doc = $doc]
+            )*
+            pub const $err: super::Error = super::Error(-(crate::bindings::$err as i32));
+        };
+    }
+
+    declare_err!(EPERM, "Operation not permitted.");
+    declare_err!(ENOENT, "No such file or directory.");
+    declare_err!(ESRCH, "No such process.");
+    declare_err!(EINTR, "Interrupted system call.");
+    declare_err!(EIO, "I/O error.");
+    declare_err!(ENXIO, "No such device or address.");
+    declare_err!(E2BIG, "Argument list too long.");
+    declare_err!(ENOEXEC, "Exec format error.");
+    declare_err!(EBADF, "Bad file number.");
+    declare_err!(ECHILD, "Exec format error.");
+    declare_err!(EAGAIN, "Try again.");
+    declare_err!(ENOMEM, "Out of memory.");
+    declare_err!(EACCES, "Permission denied.");
+    declare_err!(EFAULT, "Bad address.");
+    declare_err!(ENOTBLK, "Block device required.");
+    declare_err!(EBUSY, "Device or resource busy.");
+    declare_err!(EEXIST, "File exists.");
+    declare_err!(EXDEV, "Cross-device link.");
+    declare_err!(ENODEV, "No such device.");
+    declare_err!(ENOTDIR, "Not a directory.");
+    declare_err!(EISDIR, "Is a directory.");
+    declare_err!(EINVAL, "Invalid argument.");
+    declare_err!(ENFILE, "File table overflow.");
+    declare_err!(EMFILE, "Too many open files.");
+    declare_err!(ENOTTY, "Not a typewriter.");
+    declare_err!(ETXTBSY, "Text file busy.");
+    declare_err!(EFBIG, "File too large.");
+    declare_err!(ENOSPC, "No space left on device.");
+    declare_err!(ESPIPE, "Illegal seek.");
+    declare_err!(EROFS, "Read-only file system.");
+    declare_err!(EMLINK, "Too many links.");
+    declare_err!(EPIPE, "Broken pipe.");
+    declare_err!(EDOM, "Math argument out of domain of func.");
+    declare_err!(ERANGE, "Math result not representable.");
 }
 
 /// Generic integer kernel error.
@@ -30,12 +78,48 @@ impl Error {
     }
 }
 
+impl From<AllocError> for Error {
+    fn from(_: AllocError) -> Error {
+        code::ENOMEM
+    }
+}
+
+impl From<TryFromIntError> for Error {
+    fn from(_: TryFromIntError) -> Error {
+        code::EINVAL
+    }
+}
+
+impl From<Utf8Error> for Error {
+    fn from(_: Utf8Error) -> Error {
+        code::EINVAL
+    }
+}
+
 impl From<TryReserveError> for Error {
     fn from(_: TryReserveError) -> Error {
         code::ENOMEM
     }
 }
 
+impl From<LayoutError> for Error {
+    fn from(_: LayoutError) -> Error {
+        code::ENOMEM
+    }
+}
+
+impl From<core::fmt::Error> for Error {
+    fn from(_: core::fmt::Error) -> Error {
+        code::EINVAL
+    }
+}
+
+impl From<core::convert::Infallible> for Error {
+    fn from(e: core::convert::Infallible) -> Error {
+        match e {}
+    }
+}
+
 /// A [`Result`] with an [`Error`] error type.
 ///
 /// To be used as the return type for functions that may fail.

rust/kernel/lib.rs

@@ -12,6 +12,7 @@
 //! do so first instead of bypassing this crate.
 
 #![no_std]
+#![feature(allocator_api)]
 #![feature(core_ffi_c)]
 
 // Ensure conditional compilation based on the kernel configuration works;
@@ -22,15 +23,23 @@ compile_error!("Missing kernel configuration for conditional compilation");
 #[cfg(not(test))]
 #[cfg(not(testlib))]
 mod allocator;
+mod build_assert;
 pub mod error;
 pub mod prelude;
 pub mod print;
+mod static_assert;
+#[doc(hidden)]
+pub mod std_vendor;
 pub mod str;
+pub mod types;
 
 #[doc(hidden)]
 pub use bindings;
 pub use macros;
 
+#[doc(hidden)]
+pub use build_error::build_error;
+
 /// Prefix to appear before log messages printed from within the `kernel` crate.
 const __LOG_PREFIX: &[u8] = b"rust_kernel\0";
 

rust/kernel/prelude.rs

@@ -11,10 +11,18 @@
 //! use kernel::prelude::*;
 //! ```
 
-pub use super::{
-    error::{Error, Result},
-    pr_emerg, pr_info, ThisModule,
-};
-pub use alloc::{boxed::Box, vec::Vec};
 pub use core::pin::Pin;
-pub use macros::module;
+
+pub use alloc::{boxed::Box, vec::Vec};
+
+pub use macros::{module, vtable};
+
+pub use super::build_assert;
+
+pub use super::{dbg, pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
+
+pub use super::static_assert;
+
+pub use super::error::{code::*, Error, Result};
+
+pub use super::{str::CStr, ThisModule};

rust/kernel/print.rs

@@ -74,7 +74,14 @@ pub mod format_strings {
     // 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`].
@@ -105,6 +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.
@@ -114,7 +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
@@ -128,6 +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
@@ -168,7 +202,127 @@ 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)*)
+    )
+);
+
+/// 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)*)
     )
 );
 
@@ -193,6 +347,60 @@ macro_rules! pr_emerg (
 #[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)*)
+    )
+);
+
+/// 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)*)
     )
 );

rust/kernel/static_assert.rs

+// SPDX-License-Identifier: GPL-2.0
+
+//! Static assert.
+
+/// Static assert (i.e. compile-time assert).
+///
+/// Similar to C11 [`_Static_assert`] and C++11 [`static_assert`].
+///
+/// The feature may be added to Rust in the future: see [RFC 2790].
+///
+/// [`_Static_assert`]: https://en.cppreference.com/w/c/language/_Static_assert
+/// [`static_assert`]: https://en.cppreference.com/w/cpp/language/static_assert
+/// [RFC 2790]: https://github.com/rust-lang/rfcs/issues/2790
+///
+/// # Examples
+///
+/// ```
+/// static_assert!(42 > 24);
+/// static_assert!(core::mem::size_of::<u8>() == 1);
+///
+/// const X: &[u8] = b"bar";
+/// static_assert!(X[1] == b'a');
+///
+/// const fn f(x: i32) -> i32 {
+///     x + 2
+/// }
+/// static_assert!(f(40) == 42);
+/// ```
+#[macro_export]
+macro_rules! static_assert {
+    ($condition:expr) => {
+        const _: () = core::assert!($condition);
+    };
+}

rust/kernel/std_vendor.rs

+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! The contents of this file come from the Rust standard library, hosted in
+//! the <https://github.com/rust-lang/rust> repository, licensed under
+//! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,
+//! see <https://github.com/rust-lang/rust/blob/master/COPYRIGHT>.
+
+/// [`std::dbg`], but using [`pr_info`] instead of [`eprintln`].
+///
+/// Prints and returns the value of a given expression for quick and dirty
+/// debugging.
+///
+/// An example:
+///
+/// ```rust
+/// let a = 2;
+/// # #[allow(clippy::dbg_macro)]
+/// let b = dbg!(a * 2) + 1;
+/// //      ^-- prints: [src/main.rs:2] a * 2 = 4
+/// assert_eq!(b, 5);
+/// ```
+///
+/// The macro works by using the `Debug` implementation of the type of
+/// the given expression to print the value with [`printk`] along with the
+/// source location of the macro invocation as well as the source code
+/// of the expression.
+///
+/// Invoking the macro on an expression moves and takes ownership of it
+/// before returning the evaluated expression unchanged. If the type
+/// of the expression does not implement `Copy` and you don't want
+/// to give up ownership, you can instead borrow with `dbg!(&expr)`
+/// for some expression `expr`.
+///
+/// The `dbg!` macro works exactly the same in release builds.
+/// This is useful when debugging issues that only occur in release
+/// builds or when debugging in release mode is significantly faster.
+///
+/// Note that the macro is intended as a temporary debugging tool to be
+/// used during development. Therefore, avoid committing `dbg!` macro
+/// invocations into the kernel tree.
+///
+/// For debug output that is intended to be kept in the kernel tree,
+/// use [`pr_debug`] and similar facilities instead.
+///
+/// # Stability
+///
+/// The exact output printed by this macro should not be relied upon
+/// and is subject to future changes.
+///
+/// # Further examples
+///
+/// With a method call:
+///
+/// ```rust
+/// # #[allow(clippy::dbg_macro)]
+/// fn foo(n: usize) {
+///     if dbg!(n.checked_sub(4)).is_some() {
+///         // ...
+///     }
+/// }
+///
+/// foo(3)
+/// ```
+///
+/// This prints to the kernel log:
+///
+/// ```text,ignore
+/// [src/main.rs:4] n.checked_sub(4) = None
+/// ```
+///
+/// Naive factorial implementation:
+///
+/// ```rust
+/// # #[allow(clippy::dbg_macro)]
+/// # {
+/// fn factorial(n: u32) -> u32 {
+///     if dbg!(n <= 1) {
+///         dbg!(1)
+///     } else {
+///         dbg!(n * factorial(n - 1))
+///     }
+/// }
+///
+/// dbg!(factorial(4));
+/// # }
+/// ```
+///
+/// This prints to the kernel log:
+///
+/// ```text,ignore
+/// [src/main.rs:3] n <= 1 = false
+/// [src/main.rs:3] n <= 1 = false
+/// [src/main.rs:3] n <= 1 = false
+/// [src/main.rs:3] n <= 1 = true
+/// [src/main.rs:4] 1 = 1
+/// [src/main.rs:5] n * factorial(n - 1) = 2
+/// [src/main.rs:5] n * factorial(n - 1) = 6
+/// [src/main.rs:5] n * factorial(n - 1) = 24
+/// [src/main.rs:11] factorial(4) = 24
+/// ```
+///
+/// The `dbg!(..)` macro moves the input:
+///
+/// ```ignore
+/// /// A wrapper around `usize` which importantly is not Copyable.
+/// #[derive(Debug)]
+/// struct NoCopy(usize);
+///
+/// let a = NoCopy(42);
+/// let _ = dbg!(a); // <-- `a` is moved here.
+/// let _ = dbg!(a); // <-- `a` is moved again; error!
+/// ```
+///
+/// You can also use `dbg!()` without a value to just print the
+/// file and line whenever it's reached.
+///
+/// Finally, if you want to `dbg!(..)` multiple values, it will treat them as
+/// a tuple (and return it, too):
+///
+/// ```
+/// # #[allow(clippy::dbg_macro)]
+/// assert_eq!(dbg!(1usize, 2u32), (1, 2));
+/// ```
+///
+/// However, a single argument with a trailing comma will still not be treated
+/// as a tuple, following the convention of ignoring trailing commas in macro
+/// invocations. You can use a 1-tuple directly if you need one:
+///
+/// ```
+/// # #[allow(clippy::dbg_macro)]
+/// # {
+/// assert_eq!(1, dbg!(1u32,)); // trailing comma ignored
+/// assert_eq!((1,), dbg!((1u32,))); // 1-tuple
+/// # }
+/// ```
+///
+/// [`std::dbg`]: https://doc.rust-lang.org/std/macro.dbg.html
+/// [`eprintln`]: https://doc.rust-lang.org/std/macro.eprintln.html
+/// [`printk`]: https://www.kernel.org/doc/html/latest/core-api/printk-basics.html
+#[macro_export]
+macro_rules! dbg {
+    // NOTE: We cannot use `concat!` to make a static string as a format argument
+    // of `pr_info!` because `file!` could contain a `{` or
+    // `$val` expression could be a block (`{ .. }`), in which case the `pr_info!`
+    // will be malformed.
+    () => {
+        $crate::pr_info!("[{}:{}]\n", ::core::file!(), ::core::line!())
+    };
+    ($val:expr $(,)?) => {
+        // Use of `match` here is intentional because it affects the lifetimes
+        // of temporaries - https://stackoverflow.com/a/48732525/1063961
+        match $val {
+            tmp => {
+                $crate::pr_info!("[{}:{}] {} = {:#?}\n",
+                    ::core::file!(), ::core::line!(), ::core::stringify!($val), &tmp);
+                tmp
+            }
+        }
+    };
+    ($($val:expr),+ $(,)?) => {
+        ($($crate::dbg!($val)),+,)
+    };
+}

rust/kernel/types.rs

+// SPDX-License-Identifier: GPL-2.0
+
+//! Kernel types.
+
+use core::{cell::UnsafeCell, mem::MaybeUninit};
+
+/// Stores an opaque value.
+///
+/// This is meant to be used with FFI objects that are never interpreted by Rust code.
+#[repr(transparent)]
+pub struct Opaque<T>(MaybeUninit<UnsafeCell<T>>);
+
+impl<T> Opaque<T> {
+    /// Creates a new opaque value.
+    pub const fn new(value: T) -> Self {
+        Self(MaybeUninit::new(UnsafeCell::new(value)))
+    }
+
+    /// Creates an uninitialised value.
+    pub const fn uninit() -> Self {
+        Self(MaybeUninit::uninit())
+    }
+
+    /// Returns a raw pointer to the opaque data.
+    pub fn get(&self) -> *mut T {
+        UnsafeCell::raw_get(self.0.as_ptr())
+    }
+}
+
+/// A sum type that always holds either a value of type `L` or `R`.
+pub enum Either<L, R> {
+    /// Constructs an instance of [`Either`] containing a value of type `L`.
+    Left(L),
+
+    /// Constructs an instance of [`Either`] containing a value of type `R`.
+    Right(R),
+}

rust/macros/concat_idents.rs

+// SPDX-License-Identifier: GPL-2.0
+
+use proc_macro::{token_stream, Ident, TokenStream, TokenTree};
+
+use crate::helpers::expect_punct;
+
+fn expect_ident(it: &mut token_stream::IntoIter) -> Ident {
+    if let Some(TokenTree::Ident(ident)) = it.next() {
+        ident
+    } else {
+        panic!("Expected Ident")
+    }
+}
+
+pub(crate) fn concat_idents(ts: TokenStream) -> TokenStream {
+    let mut it = ts.into_iter();
+    let a = expect_ident(&mut it);
+    assert_eq!(expect_punct(&mut it), ',');
+    let b = expect_ident(&mut it);
+    assert!(it.next().is_none(), "only two idents can be concatenated");
+    let res = Ident::new(&format!("{a}{b}"), b.span());
+    TokenStream::from_iter([TokenTree::Ident(res)])
+}

rust/macros/helpers.rs

@@ -18,10 +18,16 @@ pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> {
     }
 }
 
-pub(crate) fn try_byte_string(it: &mut token_stream::IntoIter) -> Option<String> {
-    try_literal(it).and_then(|byte_string| {
-        if byte_string.starts_with("b\"") && byte_string.ends_with('\"') {
-            Some(byte_string[2..byte_string.len() - 1].to_string())
+pub(crate) fn try_string(it: &mut token_stream::IntoIter) -> Option<String> {
+    try_literal(it).and_then(|string| {
+        if string.starts_with('\"') && string.ends_with('\"') {
+            let content = &string[1..string.len() - 1];
+            if content.contains('\\') {
+                panic!("Escape sequences in string literals not yet handled");
+            }
+            Some(content.to_string())
+        } else if string.starts_with("r\"") {
+            panic!("Raw string literals are not yet handled");
         } else {
             None
         }
@@ -40,8 +46,14 @@ pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char {
     }
 }
 
-pub(crate) fn expect_byte_string(it: &mut token_stream::IntoIter) -> String {
-    try_byte_string(it).expect("Expected byte string")
+pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String {
+    try_string(it).expect("Expected string")
+}
+
+pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String {
+    let string = try_string(it).expect("Expected string");
+    assert!(string.is_ascii(), "Expected ASCII string");
+    string
 }
 
 pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {

rust/macros/lib.rs

@@ -2,8 +2,10 @@
 
 //! Crate for all kernel procedural macros.
 
+mod concat_idents;
 mod helpers;
 mod module;
+mod vtable;
 
 use proc_macro::TokenStream;
 
@@ -23,20 +25,20 @@ use proc_macro::TokenStream;
 ///
 /// module!{
 ///     type: MyModule,
-///     name: b"my_kernel_module",
-///     author: b"Rust for Linux Contributors",
-///     description: b"My very own kernel module!",
-///     license: b"GPL",
+///     name: "my_kernel_module",
+///     author: "Rust for Linux Contributors",
+///     description: "My very own kernel module!",
+///     license: "GPL",
 ///     params: {
 ///        my_i32: i32 {
 ///            default: 42,
 ///            permissions: 0o000,
-///            description: b"Example of i32",
+///            description: "Example of i32",
 ///        },
 ///        writeable_i32: i32 {
 ///            default: 42,
 ///            permissions: 0o644,
-///            description: b"Example of i32",
+///            description: "Example of i32",
 ///        },
 ///    },
 /// }
@@ -70,3 +72,97 @@ use proc_macro::TokenStream;
 pub fn module(ts: TokenStream) -> TokenStream {
     module::module(ts)
 }
+
+/// Declares or implements a vtable trait.
+///
+/// Linux's use of pure vtables is very close to Rust traits, but they differ
+/// in how unimplemented functions are represented. In Rust, traits can provide
+/// default implementation for all non-required methods (and the default
+/// implementation could just return `Error::EINVAL`); Linux typically use C
+/// `NULL` pointers to represent these functions.
+///
+/// This attribute is intended to close the gap. Traits can be declared and
+/// implemented with the `#[vtable]` attribute, and a `HAS_*` associated constant
+/// will be generated for each method in the trait, indicating if the implementor
+/// has overridden a method.
+///
+/// This attribute is not needed if all methods are required.
+///
+/// # Examples
+///
+/// ```ignore
+/// use kernel::prelude::*;
+///
+/// // Declares a `#[vtable]` trait
+/// #[vtable]
+/// pub trait Operations: Send + Sync + Sized {
+///     fn foo(&self) -> Result<()> {
+///         Err(EINVAL)
+///     }
+///
+///     fn bar(&self) -> Result<()> {
+///         Err(EINVAL)
+///     }
+/// }
+///
+/// struct Foo;
+///
+/// // Implements the `#[vtable]` trait
+/// #[vtable]
+/// impl Operations for Foo {
+///     fn foo(&self) -> Result<()> {
+/// #        Err(EINVAL)
+///         // ...
+///     }
+/// }
+///
+/// assert_eq!(<Foo as Operations>::HAS_FOO, true);
+/// assert_eq!(<Foo as Operations>::HAS_BAR, false);
+/// ```
+#[proc_macro_attribute]
+pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
+    vtable::vtable(attr, ts)
+}
+
+/// Concatenate two identifiers.
+///
+/// This is useful in macros that need to declare or reference items with names
+/// starting with a fixed prefix and ending in a user specified name. The resulting
+/// identifier has the span of the second argument.
+///
+/// # Examples
+///
+/// ```ignore
+/// use kernel::macro::concat_idents;
+///
+/// macro_rules! pub_no_prefix {
+///     ($prefix:ident, $($newname:ident),+) => {
+///         $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+
+///     };
+/// }
+///
+/// pub_no_prefix!(
+///     binder_driver_return_protocol_,
+///     BR_OK,
+///     BR_ERROR,
+///     BR_TRANSACTION,
+///     BR_REPLY,
+///     BR_DEAD_REPLY,
+///     BR_TRANSACTION_COMPLETE,
+///     BR_INCREFS,
+///     BR_ACQUIRE,
+///     BR_RELEASE,
+///     BR_DECREFS,
+///     BR_NOOP,
+///     BR_SPAWN_LOOPER,
+///     BR_DEAD_BINDER,
+///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
+///     BR_FAILED_REPLY
+/// );
+///
+/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
+/// ```
+#[proc_macro]
+pub fn concat_idents(ts: TokenStream) -> TokenStream {
+    concat_idents::concat_idents(ts)
+}

rust/macros/module.rs

@@ -108,11 +108,11 @@ impl ModuleInfo {
 
             match key.as_str() {
                 "type" => info.type_ = expect_ident(it),
-                "name" => info.name = expect_byte_string(it),
-                "author" => info.author = Some(expect_byte_string(it)),
-                "description" => info.description = Some(expect_byte_string(it)),
-                "license" => info.license = expect_byte_string(it),
-                "alias" => info.alias = Some(expect_byte_string(it)),
+                "name" => info.name = expect_string_ascii(it),
+                "author" => info.author = Some(expect_string(it)),
+                "description" => info.description = Some(expect_string(it)),
+                "license" => info.license = expect_string_ascii(it),
+                "alias" => info.alias = Some(expect_string_ascii(it)),
                 _ => panic!(
                     "Unknown key \"{}\". Valid keys are: {:?}.",
                     key, EXPECTED_KEYS

rust/macros/vtable.rs

+// SPDX-License-Identifier: GPL-2.0
+
+use proc_macro::{Delimiter, Group, TokenStream, TokenTree};
+use std::collections::HashSet;
+use std::fmt::Write;
+
+pub(crate) fn vtable(_attr: TokenStream, ts: TokenStream) -> TokenStream {
+    let mut tokens: Vec<_> = ts.into_iter().collect();
+
+    // Scan for the `trait` or `impl` keyword.
+    let is_trait = tokens
+        .iter()
+        .find_map(|token| match token {
+            TokenTree::Ident(ident) => match ident.to_string().as_str() {
+                "trait" => Some(true),
+                "impl" => Some(false),
+                _ => None,
+            },
+            _ => None,
+        })
+        .expect("#[vtable] attribute should only be applied to trait or impl block");
+
+    // Retrieve the main body. The main body should be the last token tree.
+    let body = match tokens.pop() {
+        Some(TokenTree::Group(group)) if group.delimiter() == Delimiter::Brace => group,
+        _ => panic!("cannot locate main body of trait or impl block"),
+    };
+
+    let mut body_it = body.stream().into_iter();
+    let mut functions = Vec::new();
+    let mut consts = HashSet::new();
+    while let Some(token) = body_it.next() {
+        match token {
+            TokenTree::Ident(ident) if ident.to_string() == "fn" => {
+                let fn_name = match body_it.next() {
+                    Some(TokenTree::Ident(ident)) => ident.to_string(),
+                    // Possibly we've encountered a fn pointer type instead.
+                    _ => continue,
+                };
+                functions.push(fn_name);
+            }
+            TokenTree::Ident(ident) if ident.to_string() == "const" => {
+                let const_name = match body_it.next() {
+                    Some(TokenTree::Ident(ident)) => ident.to_string(),
+                    // Possibly we've encountered an inline const block instead.
+                    _ => continue,
+                };
+                consts.insert(const_name);
+            }
+            _ => (),
+        }
+    }
+
+    let mut const_items;
+    if is_trait {
+        const_items = "
+                /// A marker to prevent implementors from forgetting to use [`#[vtable]`](vtable)
+                /// attribute when implementing this trait.
+                const USE_VTABLE_ATTR: ();
+        "
+        .to_owned();
+
+        for f in functions {
+            let gen_const_name = format!("HAS_{}", f.to_uppercase());
+            // Skip if it's declared already -- this allows user override.
+            if consts.contains(&gen_const_name) {
+                continue;
+            }
+            // We don't know on the implementation-site whether a method is required or provided
+            // so we have to generate a const for all methods.
+            write!(
+                const_items,
+                "/// Indicates if the `{f}` method is overridden by the implementor.
+                const {gen_const_name}: bool = false;",
+            )
+            .unwrap();
+        }
+    } else {
+        const_items = "const USE_VTABLE_ATTR: () = ();".to_owned();
+
+        for f in functions {
+            let gen_const_name = format!("HAS_{}", f.to_uppercase());
+            if consts.contains(&gen_const_name) {
+                continue;
+            }
+            write!(const_items, "const {gen_const_name}: bool = true;").unwrap();
+        }
+    }
+
+    let new_body = vec![const_items.parse().unwrap(), body.stream()]
+        .into_iter()
+        .collect();
+    tokens.push(TokenTree::Group(Group::new(Delimiter::Brace, new_body)));
+    tokens.into_iter().collect()
+}

samples/rust/Kconfig

@@ -20,6 +20,16 @@ config SAMPLE_RUST_MINIMAL
 
 	  If unsure, say N.
 
+config SAMPLE_RUST_PRINT
+	tristate "Printing macros"
+	help
+	  This option builds the Rust printing macros sample.
+
+	  To compile this as a module, choose M here:
+	  the module will be called rust_print.
+
+	  If unsure, say N.
+
 config SAMPLE_RUST_HOSTPROGS
 	bool "Host programs"
 	help

samples/rust/Makefile

 # SPDX-License-Identifier: GPL-2.0
 
 obj-$(CONFIG_SAMPLE_RUST_MINIMAL)		+= rust_minimal.o
+obj-$(CONFIG_SAMPLE_RUST_PRINT)			+= rust_print.o
 
 subdir-$(CONFIG_SAMPLE_RUST_HOSTPROGS)		+= hostprogs

samples/rust/rust_minimal.rs

@@ -6,10 +6,10 @@ use kernel::prelude::*;
 
 module! {
     type: RustMinimal,
-    name: b"rust_minimal",
-    author: b"Rust for Linux Contributors",
-    description: b"Rust minimal sample",
-    license: b"GPL",
+    name: "rust_minimal",
+    author: "Rust for Linux Contributors",
+    description: "Rust minimal sample",
+    license: "GPL",
 }
 
 struct RustMinimal {

samples/rust/rust_print.rs

+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust printing macros sample.
+
+use kernel::pr_cont;
+use kernel::prelude::*;
+
+module! {
+    type: RustPrint,
+    name: "rust_print",
+    author: "Rust for Linux Contributors",
+    description: "Rust printing macros sample",
+    license: "GPL",
+}
+
+struct RustPrint;
+
+impl kernel::Module for RustPrint {
+    fn init(_module: &'static ThisModule) -> Result<Self> {
+        pr_info!("Rust printing macros sample (init)\n");
+
+        pr_emerg!("Emergency message (level 0) without args\n");
+        pr_alert!("Alert message (level 1) without args\n");
+        pr_crit!("Critical message (level 2) without args\n");
+        pr_err!("Error message (level 3) without args\n");
+        pr_warn!("Warning message (level 4) without args\n");
+        pr_notice!("Notice message (level 5) without args\n");
+        pr_info!("Info message (level 6) without args\n");
+
+        pr_info!("A line that");
+        pr_cont!(" is continued");
+        pr_cont!(" without args\n");
+
+        pr_emerg!("{} message (level {}) with args\n", "Emergency", 0);
+        pr_alert!("{} message (level {}) with args\n", "Alert", 1);
+        pr_crit!("{} message (level {}) with args\n", "Critical", 2);
+        pr_err!("{} message (level {}) with args\n", "Error", 3);
+        pr_warn!("{} message (level {}) with args\n", "Warning", 4);
+        pr_notice!("{} message (level {}) with args\n", "Notice", 5);
+        pr_info!("{} message (level {}) with args\n", "Info", 6);
+
+        pr_info!("A {} that", "line");
+        pr_cont!(" is {}", "continued");
+        pr_cont!(" with {}\n", "args");
+
+        Ok(RustPrint)
+    }
+}
+
+impl Drop for RustPrint {
+    fn drop(&mut self) {
+        pr_info!("Rust printing macros sample (exit)\n");
+    }
+}

scripts/generate_rust_analyzer.py

@@ -67,6 +67,12 @@ def generate_crates(srctree, objtree, sysroot_src):
     )
     crates[-1]["proc_macro_dylib_path"] = "rust/libmacros.so"
 
+    append_crate(
+        "build_error",
+        srctree / "rust" / "build_error.rs",
+        ["core", "compiler_builtins"],
+    )
+
     append_crate(
         "bindings",
         srctree / "rust"/ "bindings" / "lib.rs",
@@ -78,7 +84,7 @@ def generate_crates(srctree, objtree, sysroot_src):
     append_crate(
         "kernel",
         srctree / "rust" / "kernel" / "lib.rs",
-        ["core", "alloc", "macros", "bindings"],
+        ["core", "alloc", "macros", "build_error", "bindings"],
         cfg=cfg,
     )
     crates[-1]["source"] = {