Merge tag 'rust-v6.1-rc1' of https://github.com/Rust-for-Linux/linux

Pull Rust introductory support from Kees Cook:
 "The tree has a recent base, but has fundamentally been in linux-next
  for a year and a half[1]. It's been updated based on feedback from the
  Kernel Maintainer's Summit, and to gain recent Reviewed-by: tags.

  Miguel is the primary maintainer, with me helping where needed/wanted.
  Our plan is for the tree to switch to the standard non-rebasing
  practice once this initial infrastructure series lands.

  The contents are the absolute minimum to get Rust code building in the
  kernel, with many more interfaces[2] (and drivers - NVMe[3], 9p[4], M1
  GPU[5]) on the way.

  The initial support of Rust-for-Linux comes in roughly 4 areas:

   - Kernel internals (kallsyms expansion for Rust symbols, %pA format)

   - Kbuild infrastructure (Rust build rules and support scripts)

   - Rust crates and bindings for initial minimum viable build

   - Rust kernel documentation and samples

  Rust support has been in linux-next for a year and a half now, and the
  short log doesn't do justice to the number of people who have
  contributed both to the Linux kernel side but also to the upstream
  Rust side to support the kernel's needs. Thanks to these 173 people,
  and many more, who have been involved in all kinds of ways:

  Miguel Ojeda, Wedson Almeida Filho, Alex Gaynor, Boqun Feng, Gary Guo,
  Björn Roy Baron, Andreas Hindborg, Adam Bratschi-Kaye, Benno Lossin,
  Maciej Falkowski, Finn Behrens, Sven Van Asbroeck, Asahi Lina, FUJITA
  Tomonori, John Baublitz, Wei Liu, Geoffrey Thomas, Philip Herron,
  Arthur Cohen, David Faust, Antoni Boucher, Philip Li, Yujie Liu,
  Jonathan Corbet, Greg Kroah-Hartman, Paul E. McKenney, Josh Triplett,
  Kent Overstreet, David Gow, Alice Ryhl, Robin Randhawa, Kees Cook,
  Nick Desaulniers, Matthew Wilcox, Linus Walleij, Joe Perches, Michael
  Ellerman, Petr Mladek, Masahiro Yamada, Arnaldo Carvalho de Melo,
  Andrii Nakryiko, Konstantin Shelekhin, Rasmus Villemoes, Konstantin
  Ryabitsev, Stephen Rothwell, Andy Shevchenko, Sergey Senozhatsky, John
  Paul Adrian Glaubitz, David Laight, Nathan Chancellor, Jonathan
  Cameron, Daniel Latypov, Shuah Khan, Brendan Higgins, Julia Lawall,
  Laurent Pinchart, Geert Uytterhoeven, Akira Yokosawa, Pavel Machek,
  David S. Miller, John Hawley, James Bottomley, Arnd Bergmann,
  Christian Brauner, Dan Robertson, Nicholas Piggin, Zhouyi Zhou, Elena
  Zannoni, Jose E. Marchesi, Leon Romanovsky, Will Deacon, Richard
  Weinberger, Randy Dunlap, Paolo Bonzini, Roland Dreier, Mark Brown,
  Sasha Levin, Ted Ts'o, Steven Rostedt, Jarkko Sakkinen, Michal
  Kubecek, Marco Elver, Al Viro, Keith Busch, Johannes Berg, Jan Kara,
  David Sterba, Connor Kuehl, Andy Lutomirski, Andrew Lunn, Alexandre
  Belloni, Peter Zijlstra, Russell King, Eric W. Biederman, Willy
  Tarreau, Christoph Hellwig, Emilio Cobos Álvarez, Christian Poveda,
  Mark Rousskov, John Ericson, TennyZhuang, Xuanwo, Daniel Paoliello,
  Manish Goregaokar, comex, Josh Stone, Stephan Sokolow, Philipp Krones,
  Guillaume Gomez, Joshua Nelson, Mats Larsen, Marc Poulhiès, Samantha
  Miller, Esteban Blanc, Martin Schmidt, Martin Rodriguez Reboredo,
  Daniel Xu, Viresh Kumar, Bartosz Golaszewski, Vegard Nossum, Milan
  Landaverde, Dariusz Sosnowski, Yuki Okushi, Matthew Bakhtiari, Wu
  XiangCheng, Tiago Lam, Boris-Chengbiao Zhou, Sumera Priyadarsini,
  Viktor Garske, Niklas Mohrin, Nándor István Krácser, Morgan Bartlett,
  Miguel Cano, Léo Lanteri Thauvin, Julian Merkle, Andreas Reindl,
  Jiapeng Chong, Fox Chen, Douglas Su, Antonio Terceiro, SeongJae Park,
  Sergio González Collado, Ngo Iok Ui (Wu Yu Wei), Joshua Abraham,
  Milan, Daniel Kolsoi, ahomescu, Manas, Luis Gerhorst, Li Hongyu,
  Philipp Gesang, Russell Currey, Jalil David Salamé Messina, Jon Olson,
  Raghvender, Angelos, Kaviraj Kanagaraj, Paul Römer, Sladyn Nunes,
  Mauro Baladés, Hsiang-Cheng Yang, Abhik Jain, Hongyu Li, Sean Nash,
  Yuheng Su, Peng Hao, Anhad Singh, Roel Kluin, Sara Saa, Geert
  Stappers, Garrett LeSage, IFo Hancroft, and Linus Torvalds"

Link: https://lwn.net/Articles/849849/ [1]
Link: https://github.com/Rust-for-Linux/linux/commits/rust [2]
Link: https://github.com/metaspace/rust-linux/commit/d88c3744d6cbdf11767e08bad56cbfb67c4c96d0 [3]
Link: https://github.com/wedsonaf/linux/commit/9367032607f7670de0ba1537cf09ab0f4365a338 [4]
Link: https://github.com/AsahiLinux/linux/commits/gpu/rust-wip [5]

* tag 'rust-v6.1-rc1' of https://github.com/Rust-for-Linux/linux: (27 commits)
  MAINTAINERS: Rust
  samples: add first Rust examples
  x86: enable initial Rust support
  docs: add Rust documentation
  Kbuild: add Rust support
  rust: add `.rustfmt.toml`
  scripts: add `is_rust_module.sh`
  scripts: add `rust_is_available.sh`
  scripts: add `generate_rust_target.rs`
  scripts: add `generate_rust_analyzer.py`
  scripts: decode_stacktrace: demangle Rust symbols
  scripts: checkpatch: enable language-independent checks for Rust
  scripts: checkpatch: diagnose uses of `%pA` in the C side as errors
  vsprintf: add new `%pA` format specifier
  rust: export generated symbols
  rust: add `kernel` crate
  rust: add `bindings` crate
  rust: add `macros` crate
  rust: add `compiler_builtins` crate
  rust: adapt `alloc` crate to the kernel
  ...

1 files changed, 440 insertions, 0 deletions

diff --git a/rust/alloc/alloc.rs b/rust/alloc/alloc.rs
new file mode 100644
index 000000000000..ca224a541770
--- /dev/null
+++ b/rust/alloc/alloc.rs
@@ -0,0 +1,440 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Memory allocation APIs
+
+#![stable(feature = "alloc_module", since = "1.28.0")]
+
+#[cfg(not(test))]
+use core::intrinsics;
+use core::intrinsics::{min_align_of_val, size_of_val};
+
+use core::ptr::Unique;
+#[cfg(not(test))]
+use core::ptr::{self, NonNull};
+
+#[stable(feature = "alloc_module", since = "1.28.0")]
+#[doc(inline)]
+pub use core::alloc::*;
+
+use core::marker::Destruct;
+
+#[cfg(test)]
+mod tests;
+
+extern "Rust" {
+    // These are the magic symbols to call the global allocator.  rustc generates
+    // them to call `__rg_alloc` etc. if there is a `#[global_allocator]` attribute
+    // (the code expanding that attribute macro generates those functions), or to call
+    // the default implementations in libstd (`__rdl_alloc` etc. in `library/std/src/alloc.rs`)
+    // otherwise.
+    // The rustc fork of LLVM also special-cases these function names to be able to optimize them
+    // like `malloc`, `realloc`, and `free`, respectively.
+    #[rustc_allocator]
+    #[rustc_allocator_nounwind]
+    fn __rust_alloc(size: usize, align: usize) -> *mut u8;
+    #[rustc_allocator_nounwind]
+    fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize);
+    #[rustc_allocator_nounwind]
+    fn __rust_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8;
+    #[rustc_allocator_nounwind]
+    fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8;
+}
+
+/// The global memory allocator.
+///
+/// This type implements the [`Allocator`] trait by forwarding calls
+/// to the allocator registered with the `#[global_allocator]` attribute
+/// if there is one, or the `std` crate’s default.
+///
+/// Note: while this type is unstable, the functionality it provides can be
+/// accessed through the [free functions in `alloc`](self#functions).
+#[unstable(feature = "allocator_api", issue = "32838")]
+#[derive(Copy, Clone, Default, Debug)]
+#[cfg(not(test))]
+pub struct Global;
+
+#[cfg(test)]
+pub use std::alloc::Global;
+
+/// Allocate memory with the global allocator.
+///
+/// This function forwards calls to the [`GlobalAlloc::alloc`] method
+/// of the allocator registered with the `#[global_allocator]` attribute
+/// if there is one, or the `std` crate’s default.
+///
+/// This function is expected to be deprecated in favor of the `alloc` method
+/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
+///
+/// # Safety
+///
+/// See [`GlobalAlloc::alloc`].
+///
+/// # Examples
+///
+/// ```
+/// use std::alloc::{alloc, dealloc, Layout};
+///
+/// unsafe {
+///     let layout = Layout::new::<u16>();
+///     let ptr = alloc(layout);
+///
+///     *(ptr as *mut u16) = 42;
+///     assert_eq!(*(ptr as *mut u16), 42);
+///
+///     dealloc(ptr, layout);
+/// }
+/// ```
+#[stable(feature = "global_alloc", since = "1.28.0")]
+#[must_use = "losing the pointer will leak memory"]
+#[inline]
+pub unsafe fn alloc(layout: Layout) -> *mut u8 {
+    unsafe { __rust_alloc(layout.size(), layout.align()) }
+}
+
+/// Deallocate memory with the global allocator.
+///
+/// This function forwards calls to the [`GlobalAlloc::dealloc`] method
+/// of the allocator registered with the `#[global_allocator]` attribute
+/// if there is one, or the `std` crate’s default.
+///
+/// This function is expected to be deprecated in favor of the `dealloc` method
+/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
+///
+/// # Safety
+///
+/// See [`GlobalAlloc::dealloc`].
+#[stable(feature = "global_alloc", since = "1.28.0")]
+#[inline]
+pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) {
+    unsafe { __rust_dealloc(ptr, layout.size(), layout.align()) }
+}
+
+/// Reallocate memory with the global allocator.
+///
+/// This function forwards calls to the [`GlobalAlloc::realloc`] method
+/// of the allocator registered with the `#[global_allocator]` attribute
+/// if there is one, or the `std` crate’s default.
+///
+/// This function is expected to be deprecated in favor of the `realloc` method
+/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
+///
+/// # Safety
+///
+/// See [`GlobalAlloc::realloc`].
+#[stable(feature = "global_alloc", since = "1.28.0")]
+#[must_use = "losing the pointer will leak memory"]
+#[inline]
+pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+    unsafe { __rust_realloc(ptr, layout.size(), layout.align(), new_size) }
+}
+
+/// Allocate zero-initialized memory with the global allocator.
+///
+/// This function forwards calls to the [`GlobalAlloc::alloc_zeroed`] method
+/// of the allocator registered with the `#[global_allocator]` attribute
+/// if there is one, or the `std` crate’s default.
+///
+/// This function is expected to be deprecated in favor of the `alloc_zeroed` method
+/// of the [`Global`] type when it and the [`Allocator`] trait become stable.
+///
+/// # Safety
+///
+/// See [`GlobalAlloc::alloc_zeroed`].
+///
+/// # Examples
+///
+/// ```
+/// use std::alloc::{alloc_zeroed, dealloc, Layout};
+///
+/// unsafe {
+///     let layout = Layout::new::<u16>();
+///     let ptr = alloc_zeroed(layout);
+///
+///     assert_eq!(*(ptr as *mut u16), 0);
+///
+///     dealloc(ptr, layout);
+/// }
+/// ```
+#[stable(feature = "global_alloc", since = "1.28.0")]
+#[must_use = "losing the pointer will leak memory"]
+#[inline]
+pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
+    unsafe { __rust_alloc_zeroed(layout.size(), layout.align()) }
+}
+
+#[cfg(not(test))]
+impl Global {
+    #[inline]
+    fn alloc_impl(&self, layout: Layout, zeroed: bool) -> Result<NonNull<[u8]>, AllocError> {
+        match layout.size() {
+            0 => Ok(NonNull::slice_from_raw_parts(layout.dangling(), 0)),
+            // SAFETY: `layout` is non-zero in size,
+            size => unsafe {
+                let raw_ptr = if zeroed { alloc_zeroed(layout) } else { alloc(layout) };
+                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
+                Ok(NonNull::slice_from_raw_parts(ptr, size))
+            },
+        }
+    }
+
+    // SAFETY: Same as `Allocator::grow`
+    #[inline]
+    unsafe fn grow_impl(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+        zeroed: bool,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        debug_assert!(
+            new_layout.size() >= old_layout.size(),
+            "`new_layout.size()` must be greater than or equal to `old_layout.size()`"
+        );
+
+        match old_layout.size() {
+            0 => self.alloc_impl(new_layout, zeroed),
+
+            // SAFETY: `new_size` is non-zero as `old_size` is greater than or equal to `new_size`
+            // as required by safety conditions. Other conditions must be upheld by the caller
+            old_size if old_layout.align() == new_layout.align() => unsafe {
+                let new_size = new_layout.size();
+
+                // `realloc` probably checks for `new_size >= old_layout.size()` or something similar.
+                intrinsics::assume(new_size >= old_layout.size());
+
+                let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size);
+                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
+                if zeroed {
+                    raw_ptr.add(old_size).write_bytes(0, new_size - old_size);
+                }
+                Ok(NonNull::slice_from_raw_parts(ptr, new_size))
+            },
+
+            // SAFETY: because `new_layout.size()` must be greater than or equal to `old_size`,
+            // both the old and new memory allocation are valid for reads and writes for `old_size`
+            // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap
+            // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract
+            // for `dealloc` must be upheld by the caller.
+            old_size => unsafe {
+                let new_ptr = self.alloc_impl(new_layout, zeroed)?;
+                ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), old_size);
+                self.deallocate(ptr, old_layout);
+                Ok(new_ptr)
+            },
+        }
+    }
+}
+
+#[unstable(feature = "allocator_api", issue = "32838")]
+#[cfg(not(test))]
+unsafe impl Allocator for Global {
+    #[inline]
+    fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        self.alloc_impl(layout, false)
+    }
+
+    #[inline]
+    fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
+        self.alloc_impl(layout, true)
+    }
+
+    #[inline]
+    unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+        if layout.size() != 0 {
+            // SAFETY: `layout` is non-zero in size,
+            // other conditions must be upheld by the caller
+            unsafe { dealloc(ptr.as_ptr(), layout) }
+        }
+    }
+
+    #[inline]
+    unsafe fn grow(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: all conditions must be upheld by the caller
+        unsafe { self.grow_impl(ptr, old_layout, new_layout, false) }
+    }
+
+    #[inline]
+    unsafe fn grow_zeroed(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: all conditions must be upheld by the caller
+        unsafe { self.grow_impl(ptr, old_layout, new_layout, true) }
+    }
+
+    #[inline]
+    unsafe fn shrink(
+        &self,
+        ptr: NonNull<u8>,
+        old_layout: Layout,
+        new_layout: Layout,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        debug_assert!(
+            new_layout.size() <= old_layout.size(),
+            "`new_layout.size()` must be smaller than or equal to `old_layout.size()`"
+        );
+
+        match new_layout.size() {
+            // SAFETY: conditions must be upheld by the caller
+            0 => unsafe {
+                self.deallocate(ptr, old_layout);
+                Ok(NonNull::slice_from_raw_parts(new_layout.dangling(), 0))
+            },
+
+            // SAFETY: `new_size` is non-zero. Other conditions must be upheld by the caller
+            new_size if old_layout.align() == new_layout.align() => unsafe {
+                // `realloc` probably checks for `new_size <= old_layout.size()` or something similar.
+                intrinsics::assume(new_size <= old_layout.size());
+
+                let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size);
+                let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
+                Ok(NonNull::slice_from_raw_parts(ptr, new_size))
+            },
+
+            // SAFETY: because `new_size` must be smaller than or equal to `old_layout.size()`,
+            // both the old and new memory allocation are valid for reads and writes for `new_size`
+            // bytes. Also, because the old allocation wasn't yet deallocated, it cannot overlap
+            // `new_ptr`. Thus, the call to `copy_nonoverlapping` is safe. The safety contract
+            // for `dealloc` must be upheld by the caller.
+            new_size => unsafe {
+                let new_ptr = self.allocate(new_layout)?;
+                ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_mut_ptr(), new_size);
+                self.deallocate(ptr, old_layout);
+                Ok(new_ptr)
+            },
+        }
+    }
+}
+
+/// The allocator for unique pointers.
+#[cfg(all(not(no_global_oom_handling), not(test)))]
+#[lang = "exchange_malloc"]
+#[inline]
+unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
+    let layout = unsafe { Layout::from_size_align_unchecked(size, align) };
+    match Global.allocate(layout) {
+        Ok(ptr) => ptr.as_mut_ptr(),
+        Err(_) => handle_alloc_error(layout),
+    }
+}
+
+#[cfg_attr(not(test), lang = "box_free")]
+#[inline]
+#[rustc_const_unstable(feature = "const_box", issue = "92521")]
+// This signature has to be the same as `Box`, otherwise an ICE will happen.
+// When an additional parameter to `Box` is added (like `A: Allocator`), this has to be added here as
+// well.
+// For example if `Box` is changed to  `struct Box<T: ?Sized, A: Allocator>(Unique<T>, A)`,
+// this function has to be changed to `fn box_free<T: ?Sized, A: Allocator>(Unique<T>, A)` as well.
+pub(crate) const unsafe fn box_free<T: ?Sized, A: ~const Allocator + ~const Destruct>(
+    ptr: Unique<T>,
+    alloc: A,
+) {
+    unsafe {
+        let size = size_of_val(ptr.as_ref());
+        let align = min_align_of_val(ptr.as_ref());
+        let layout = Layout::from_size_align_unchecked(size, align);
+        alloc.deallocate(From::from(ptr.cast()), layout)
+    }
+}
+
+// # Allocation error handler
+
+#[cfg(not(no_global_oom_handling))]
+extern "Rust" {
+    // This is the magic symbol to call the global alloc error handler.  rustc generates
+    // it to call `__rg_oom` if there is a `#[alloc_error_handler]`, or to call the
+    // default implementations below (`__rdl_oom`) otherwise.
+    fn __rust_alloc_error_handler(size: usize, align: usize) -> !;
+}
+
+/// Abort on memory allocation error or failure.
+///
+/// Callers of memory allocation APIs wishing to abort computation
+/// in response to an allocation error are encouraged to call this function,
+/// rather than directly invoking `panic!` or similar.
+///
+/// The default behavior of this function is to print a message to standard error
+/// and abort the process.
+/// It can be replaced with [`set_alloc_error_hook`] and [`take_alloc_error_hook`].
+///
+/// [`set_alloc_error_hook`]: ../../std/alloc/fn.set_alloc_error_hook.html
+/// [`take_alloc_error_hook`]: ../../std/alloc/fn.take_alloc_error_hook.html
+#[stable(feature = "global_alloc", since = "1.28.0")]
+#[rustc_const_unstable(feature = "const_alloc_error", issue = "92523")]
+#[cfg(all(not(no_global_oom_handling), not(test)))]
+#[cold]
+pub const fn handle_alloc_error(layout: Layout) -> ! {
+    const fn ct_error(_: Layout) -> ! {
+        panic!("allocation failed");
+    }
+
+    fn rt_error(layout: Layout) -> ! {
+        unsafe {
+            __rust_alloc_error_handler(layout.size(), layout.align());
+        }
+    }
+
+    unsafe { core::intrinsics::const_eval_select((layout,), ct_error, rt_error) }
+}
+
+// For alloc test `std::alloc::handle_alloc_error` can be used directly.
+#[cfg(all(not(no_global_oom_handling), test))]
+pub use std::alloc::handle_alloc_error;
+
+#[cfg(all(not(no_global_oom_handling), not(test)))]
+#[doc(hidden)]
+#[allow(unused_attributes)]
+#[unstable(feature = "alloc_internals", issue = "none")]
+pub mod __alloc_error_handler {
+    use crate::alloc::Layout;
+
+    // called via generated `__rust_alloc_error_handler`
+
+    // if there is no `#[alloc_error_handler]`
+    #[rustc_std_internal_symbol]
+    pub unsafe extern "C-unwind" fn __rdl_oom(size: usize, _align: usize) -> ! {
+        panic!("memory allocation of {size} bytes failed")
+    }
+
+    // if there is an `#[alloc_error_handler]`
+    #[rustc_std_internal_symbol]
+    pub unsafe extern "C-unwind" fn __rg_oom(size: usize, align: usize) -> ! {
+        let layout = unsafe { Layout::from_size_align_unchecked(size, align) };
+        extern "Rust" {
+            #[lang = "oom"]
+            fn oom_impl(layout: Layout) -> !;
+        }
+        unsafe { oom_impl(layout) }
+    }
+}
+
+/// Specialize clones into pre-allocated, uninitialized memory.
+/// Used by `Box::clone` and `Rc`/`Arc::make_mut`.
+pub(crate) trait WriteCloneIntoRaw: Sized {
+    unsafe fn write_clone_into_raw(&self, target: *mut Self);
+}
+
+impl<T: Clone> WriteCloneIntoRaw for T {
+    #[inline]
+    default unsafe fn write_clone_into_raw(&self, target: *mut Self) {
+        // Having allocated *first* may allow the optimizer to create
+        // the cloned value in-place, skipping the local and move.
+        unsafe { target.write(self.clone()) };
+    }
+}
+
+impl<T: Copy> WriteCloneIntoRaw for T {
+    #[inline]
+    unsafe fn write_clone_into_raw(&self, target: *mut Self) {
+        // We can always copy in-place, without ever involving a local value.
+        unsafe { target.copy_from_nonoverlapping(self, 1) };
+    }
+}