Rust fixes for v6.14 (3rd)

Toolchain and infrastructure:
 
  - Disallow BTF generation with Rust + LTO.
 
  - Improve rust-analyzer support.
 
 'kernel' crate:
 
  - 'init' module: remove 'Zeroable' implementation for a couple types
    that should not have it.
 
  - 'alloc' module: fix macOS failure in host test by satisfying POSIX
    alignment requirement.
 
  - Add missing '\n's to 'pr_*!()' calls.
 
 And a couple other minor cleanups.
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCgAdFiEEPjU5OPd5QIZ9jqqOGXyLc2htIW0FAmfV7lAACgkQGXyLc2ht
 IW3wSg/+KEb8mYb4F/dazuCw5LlX9kM3g/5j5KsY6ClFuOkPyRkIMiTSAlaPs80u
 eX9qM2BErX5pSsh58pxsC6fIMMf1nuZlq9pr+cGTdyo/tL5jhssJobNFD+/fnIAf
 vTdik2+aOCCZZGJ4kWWHSodF0oPQR7GrpvbvLCR9ngwG1TKn2iwDN/9YDzstt3KA
 e+oQpirw0/Ev8Cm9I2NmD1i7rA00YHLNEif9bvm1MJbA9PLFkW2g9Zxz+698Uu+P
 7dmAQYN8LeiMOPKPadQjw4/n4K6IPIiuDPtxYLF6JL3cg7UD0nd4Uy52MA8xSk9D
 Z+wxVSdqTw+tOGFQTMFMAo65+H3zri7ZCjALybYVYgHdWIyZrAN8OGYpTRYYZgqf
 z4JwYxBiyPWhoNlcu1kIWwtMW/Nbi2e44DpReddzdgPewE9XHYi6EXiiKGrlu2vP
 h8BItBwlqsCwiogGKW4+s3VvZmOijrwXvu1XfjlFQ8NCLc2wxaUkcjgsTb2kTOEI
 YWTVhS0Ggxz1CbEoFnpwLjlE0qku6DCWIFeo0WslUEK/XXYm7H7DUPY9hME5sQ/5
 dQ96A/PDP1eLDM375A7ccN6eUNejzWRYpZnGtT9PvQSNmZ24eSzjvrBaUYD3/qDG
 PzbyuSZFBoysNS312mgoCRKYBqzit+GRqgwiuAez0RiJeJV+b6Y=
 =F4QT
 -----END PGP SIGNATURE-----

Merge tag 'rust-fixes-6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull rust fixes from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Disallow BTF generation with Rust + LTO

   - Improve rust-analyzer support

  'kernel' crate:

   - 'init' module: remove 'Zeroable' implementation for a couple types
     that should not have it

   - 'alloc' module: fix macOS failure in host test by satisfying POSIX
     alignment requirement

   - Add missing '\n's to 'pr_*!()' calls

  And a couple other minor cleanups"

* tag 'rust-fixes-6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
  scripts: generate_rust_analyzer: add uapi crate
  scripts: generate_rust_analyzer: add missing include_dirs
  scripts: generate_rust_analyzer: add missing macros deps
  rust: Disallow BTF generation with Rust + LTO
  rust: task: fix `SAFETY` comment in `Task::wake_up`
  rust: workqueue: add missing newline to pr_info! examples
  rust: sync: add missing newline in locked_by log example
  rust: init: add missing newline to pr_info! calls
  rust: error: add missing newline to pr_warn! calls
  rust: docs: add missing newline to printing macro examples
  rust: alloc: satisfy POSIX alignment requirement
  rust: init: fix `Zeroable` implementation for `Option<NonNull<T>>` and `Option<KBox<T>>`
  rust: remove leftover mentions of the `alloc` crate

Documentation/rust/quick-start.rst

@@ -145,7 +145,7 @@ Rust standard library source
 ****************************
 
 The Rust standard library source is required because the build system will
-cross-compile ``core`` and ``alloc``.
+cross-compile ``core``.
 
 If ``rustup`` is being used, run::
 

Documentation/rust/testing.rst

@@ -97,7 +97,7 @@ operator are also supported as usual, e.g.:
 
 	/// ```
 	/// # use kernel::{spawn_work_item, workqueue};
-	/// spawn_work_item!(workqueue::system(), || pr_info!("x"))?;
+	/// spawn_work_item!(workqueue::system(), || pr_info!("x\n"))?;
 	/// # Ok::<(), Error>(())
 	/// ```
 

init/Kconfig

@@ -1973,7 +1973,7 @@ config RUST
 	depends on !MODVERSIONS || GENDWARFKSYMS
 	depends on !GCC_PLUGIN_RANDSTRUCT
 	depends on !RANDSTRUCT
-	depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
+	depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
 	depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
 	select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG
 	depends on !CALL_PADDING || RUSTC_VERSION >= 108100

rust/kernel/alloc/allocator_test.rs

@@ -62,6 +62,24 @@ unsafe impl Allocator for Cmalloc {
             ));
         }
 
+        // ISO C (ISO/IEC 9899:2011) defines `aligned_alloc`:
+        //
+        // > The value of alignment shall be a valid alignment supported by the implementation
+        // [...].
+        //
+        // As an example of the "supported by the implementation" requirement, POSIX.1-2001 (IEEE
+        // 1003.1-2001) defines `posix_memalign`:
+        //
+        // > The value of alignment shall be a power of two multiple of sizeof (void *).
+        //
+        // and POSIX-based implementations of `aligned_alloc` inherit this requirement. At the time
+        // of writing, this is known to be the case on macOS (but not in glibc).
+        //
+        // Satisfy the stricter requirement to avoid spurious test failures on some platforms.
+        let min_align = core::mem::size_of::<*const crate::ffi::c_void>();
+        let layout = layout.align_to(min_align).map_err(|_| AllocError)?;
+        let layout = layout.pad_to_align();
+
         // SAFETY: Returns either NULL or a pointer to a memory allocation that satisfies or
         // exceeds the given size and alignment requirements.
         let dst = unsafe { libc_aligned_alloc(layout.align(), layout.size()) } as *mut u8;

rust/kernel/error.rs

@@ -107,7 +107,7 @@ impl Error {
         } else {
             // TODO: Make it a `WARN_ONCE` once available.
             crate::pr_warn!(
-                "attempted to create `Error` with out of range `errno`: {}",
+                "attempted to create `Error` with out of range `errno`: {}\n",
                 errno
             );
             code::EINVAL

rust/kernel/init.rs

@@ -259,7 +259,7 @@ pub mod macros;
 ///     },
 /// }));
 /// let foo: Pin<&mut Foo> = foo;
-/// pr_info!("a: {}", &*foo.a.lock());
+/// pr_info!("a: {}\n", &*foo.a.lock());
 /// ```
 ///
 /// # Syntax
@@ -319,7 +319,7 @@ macro_rules! stack_pin_init {
 ///     }, GFP_KERNEL)?,
 /// }));
 /// let foo = foo.unwrap();
-/// pr_info!("a: {}", &*foo.a.lock());
+/// pr_info!("a: {}\n", &*foo.a.lock());
 /// ```
 ///
 /// ```rust,ignore
@@ -352,7 +352,7 @@ macro_rules! stack_pin_init {
 ///         x: 64,
 ///     }, GFP_KERNEL)?,
 /// }));
-/// pr_info!("a: {}", &*foo.a.lock());
+/// pr_info!("a: {}\n", &*foo.a.lock());
 /// # Ok::<_, AllocError>(())
 /// ```
 ///
@@ -882,7 +882,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
     ///
     /// impl Foo {
     ///     fn setup(self: Pin<&mut Self>) {
-    ///         pr_info!("Setting up foo");
+    ///         pr_info!("Setting up foo\n");
     ///     }
     /// }
     ///
@@ -986,7 +986,7 @@ pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> {
     ///
     /// impl Foo {
     ///     fn setup(&mut self) {
-    ///         pr_info!("Setting up foo");
+    ///         pr_info!("Setting up foo\n");
     ///     }
     /// }
     ///
@@ -1336,7 +1336,7 @@ impl<T> InPlaceWrite<T> for UniqueArc<MaybeUninit<T>> {
 /// #[pinned_drop]
 /// impl PinnedDrop for Foo {
 ///     fn drop(self: Pin<&mut Self>) {
-///         pr_info!("Foo is being dropped!");
+///         pr_info!("Foo is being dropped!\n");
 ///     }
 /// }
 /// ```
@@ -1418,17 +1418,14 @@ impl_zeroable! {
     // SAFETY: `T: Zeroable` and `UnsafeCell` is `repr(transparent)`.
     {<T: ?Sized + Zeroable>} UnsafeCell<T>,
 
-    // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
+    // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
+    // https://doc.rust-lang.org/stable/std/option/index.html#representation).
     Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>,
     Option<NonZeroU128>, Option<NonZeroUsize>,
     Option<NonZeroI8>, Option<NonZeroI16>, Option<NonZeroI32>, Option<NonZeroI64>,
     Option<NonZeroI128>, Option<NonZeroIsize>,
-
-    // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
-    //
-    // In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant.
-    {<T: ?Sized>} Option<NonNull<T>>,
-    {<T: ?Sized>} Option<KBox<T>>,
+    {<T>} Option<NonNull<T>>,
+    {<T>} Option<KBox<T>>,
 
     // SAFETY: `null` pointer is valid.
     //

rust/kernel/init/macros.rs

@@ -45,7 +45,7 @@
 //! #[pinned_drop]
 //! impl PinnedDrop for Foo {
 //!     fn drop(self: Pin<&mut Self>) {
-//!         pr_info!("{self:p} is getting dropped.");
+//!         pr_info!("{self:p} is getting dropped.\n");
 //!     }
 //! }
 //!
@@ -412,7 +412,7 @@
 //! #[pinned_drop]
 //! impl PinnedDrop for Foo {
 //!     fn drop(self: Pin<&mut Self>) {
-//!         pr_info!("{self:p} is getting dropped.");
+//!         pr_info!("{self:p} is getting dropped.\n");
 //!     }
 //! }
 //! ```
@@ -423,7 +423,7 @@
 //! // `unsafe`, full path and the token parameter are added, everything else stays the same.
 //! unsafe impl ::kernel::init::PinnedDrop for Foo {
 //!     fn drop(self: Pin<&mut Self>, _: ::kernel::init::__internal::OnlyCallFromDrop) {
-//!         pr_info!("{self:p} is getting dropped.");
+//!         pr_info!("{self:p} is getting dropped.\n");
 //!     }
 //! }
 //! ```

rust/kernel/lib.rs

@@ -6,7 +6,7 @@
 //! usage by Rust code in the kernel and is shared by all of them.
 //!
 //! In other words, all the rest of the Rust code in the kernel (e.g. kernel
-//! modules written in Rust) depends on [`core`], [`alloc`] and this crate.
+//! modules written in Rust) depends on [`core`] and this crate.
 //!
 //! If you need a kernel C API that is not ported or wrapped yet here, then
 //! do so first instead of bypassing this crate.

rust/kernel/sync/locked_by.rs

@@ -55,7 +55,7 @@ use core::{cell::UnsafeCell, mem::size_of, ptr};
 /// fn print_bytes_used(dir: &Directory, file: &File) {
 ///     let guard = dir.inner.lock();
 ///     let inner_file = file.inner.access(&guard);
-///     pr_info!("{} {}", guard.bytes_used, inner_file.bytes_used);
+///     pr_info!("{} {}\n", guard.bytes_used, inner_file.bytes_used);
 /// }
 ///
 /// /// Increments `bytes_used` for both the directory and file.

rust/kernel/task.rs

@@ -320,7 +320,7 @@ impl Task {
 
     /// Wakes up the task.
     pub fn wake_up(&self) {
-        // SAFETY: It's always safe to call `signal_pending` on a valid task, even if the task
+        // SAFETY: It's always safe to call `wake_up_process` on a valid task, even if the task
         // running.
         unsafe { bindings::wake_up_process(self.as_ptr()) };
     }

rust/kernel/workqueue.rs

@@ -60,7 +60,7 @@
 //!     type Pointer = Arc<MyStruct>;
 //!
 //!     fn run(this: Arc<MyStruct>) {
-//!         pr_info!("The value is: {}", this.value);
+//!         pr_info!("The value is: {}\n", this.value);
 //!     }
 //! }
 //!
@@ -108,7 +108,7 @@
 //!     type Pointer = Arc<MyStruct>;
 //!
 //!     fn run(this: Arc<MyStruct>) {
-//!         pr_info!("The value is: {}", this.value_1);
+//!         pr_info!("The value is: {}\n", this.value_1);
 //!     }
 //! }
 //!
@@ -116,7 +116,7 @@
 //!     type Pointer = Arc<MyStruct>;
 //!
 //!     fn run(this: Arc<MyStruct>) {
-//!         pr_info!("The second value is: {}", this.value_2);
+//!         pr_info!("The second value is: {}\n", this.value_2);
 //!     }
 //! }
 //!

scripts/generate_rust_analyzer.py

@@ -57,14 +57,26 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
         crates_indexes[display_name] = len(crates)
         crates.append(crate)
 
-    # First, the ones in `rust/` since they are a bit special.
-    append_crate(
-        "core",
-        sysroot_src / "core" / "src" / "lib.rs",
-        [],
-        cfg=crates_cfgs.get("core", []),
-        is_workspace_member=False,
-    )
+    def append_sysroot_crate(
+        display_name,
+        deps,
+        cfg=[],
+    ):
+        append_crate(
+            display_name,
+            sysroot_src / display_name / "src" / "lib.rs",
+            deps,
+            cfg,
+            is_workspace_member=False,
+        )
+
+    # NB: sysroot crates reexport items from one another so setting up our transitive dependencies
+    # here is important for ensuring that rust-analyzer can resolve symbols. The sources of truth
+    # for this dependency graph are `(sysroot_src / crate / "Cargo.toml" for crate in crates)`.
+    append_sysroot_crate("core", [], cfg=crates_cfgs.get("core", []))
+    append_sysroot_crate("alloc", ["core"])
+    append_sysroot_crate("std", ["alloc", "core"])
+    append_sysroot_crate("proc_macro", ["core", "std"])
 
     append_crate(
         "compiler_builtins",
@@ -75,7 +87,7 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
     append_crate(
         "macros",
         srctree / "rust" / "macros" / "lib.rs",
-        [],
+        ["std", "proc_macro"],
         is_proc_macro=True,
     )
 
@@ -85,27 +97,28 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
         ["core", "compiler_builtins"],
     )
 
-    append_crate(
-        "bindings",
-        srctree / "rust"/ "bindings" / "lib.rs",
-        ["core"],
-        cfg=cfg,
-    )
-    crates[-1]["env"]["OBJTREE"] = str(objtree.resolve(True))
+    def append_crate_with_generated(
+        display_name,
+        deps,
+    ):
+        append_crate(
+            display_name,
+            srctree / "rust"/ display_name / "lib.rs",
+            deps,
+            cfg=cfg,
+        )
+        crates[-1]["env"]["OBJTREE"] = str(objtree.resolve(True))
+        crates[-1]["source"] = {
+            "include_dirs": [
+                str(srctree / "rust" / display_name),
+                str(objtree / "rust")
+            ],
+            "exclude_dirs": [],
+        }
 
-    append_crate(
-        "kernel",
-        srctree / "rust" / "kernel" / "lib.rs",
-        ["core", "macros", "build_error", "bindings"],
-        cfg=cfg,
-    )
-    crates[-1]["source"] = {
-        "include_dirs": [
-            str(srctree / "rust" / "kernel"),
-            str(objtree / "rust")
-        ],
-        "exclude_dirs": [],
-    }
+    append_crate_with_generated("bindings", ["core"])
+    append_crate_with_generated("uapi", ["core"])
+    append_crate_with_generated("kernel", ["core", "macros", "build_error", "bindings", "uapi"])
 
     def is_root_crate(build_file, target):
         try:

scripts/rustdoc_test_gen.rs

@@ -15,8 +15,8 @@
 //!   - Test code should be able to define functions and call them, without having to carry
 //!     the context.
 //!
-//!   - Later on, we may want to be able to test non-kernel code (e.g. `core`, `alloc` or
-//!     third-party crates) which likely use the standard library `assert*!` macros.
+//!   - Later on, we may want to be able to test non-kernel code (e.g. `core` or third-party
+//!     crates) which likely use the standard library `assert*!` macros.
 //!
 //! For this reason, instead of the passed context, `kunit_get_current_test()` is used instead
 //! (i.e. `current->kunit_test`).