From fe49aae0fcb348b656bbde2eb1d1c75d8a1a5c3c Mon Sep 17 00:00:00 2001 From: Janne Grunau Date: Sat, 28 Jun 2025 13:36:00 +0200 Subject: [PATCH 1/3] rust: init: Fix generics in *_init! macros The match pattern for a optional trailing comma in the list of generics is erroneously repeated in the code block resulting in following error: | error: attempted to repeat an expression containing no syntax variables matched as repeating at this depth | --> rust/kernel/init.rs:301:73 | | | 301 | ::pin_init::try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? { | | ^^^ Remove "$(,)?" from all code blocks in the try_init! and try_pin_init! definitions. Cc: stable@vger.kernel.org Fixes: 578eb8b6db13 ("rust: pin-init: move the default error behavior of `try_[pin_]init`") Signed-off-by: Janne Grunau Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250628-rust_init_trailing_comma-v1-1-2d162ae1a757@jannau.net Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 8d228c237954..21ef202ab0db 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -231,14 +231,14 @@ macro_rules! try_init { ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }) => { - ::pin_init::try_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? { + ::pin_init::try_init!($(&$this in)? $t $(::<$($generics),*>)? { $($fields)* }? $crate::error::Error) }; ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }? $err:ty) => { - ::pin_init::try_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? { + ::pin_init::try_init!($(&$this in)? $t $(::<$($generics),*>)? { $($fields)* }? $err) }; @@ -291,14 +291,14 @@ macro_rules! try_pin_init { ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }) => { - ::pin_init::try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? { + ::pin_init::try_pin_init!($(&$this in)? $t $(::<$($generics),*>)? { $($fields)* }? $crate::error::Error) }; ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { $($fields:tt)* }? $err:ty) => { - ::pin_init::try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? { + ::pin_init::try_pin_init!($(&$this in)? $t $(::<$($generics),*>)? { $($fields)* }? $err) }; From aa7b65c2a29e8b07057b13624102c6810597c0d5 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sat, 12 Jul 2025 18:01:02 +0200 Subject: [PATCH 2/3] objtool/rust: add one more `noreturn` Rust function for Rust 1.89.0 Starting with Rust 1.89.0 (expected 2025-08-07), under `CONFIG_RUST_DEBUG_ASSERTIONS=y`, `objtool` may report: rust/kernel.o: warning: objtool: _R..._6kernel4pageNtB5_4Page8read_raw() falls through to next function _R..._6kernel4pageNtB5_4Page9write_raw() (and many others) due to calls to the `noreturn` symbol: core::panicking::panic_nounwind_fmt Thus add the mangled one to the list so that `objtool` knows it is actually `noreturn`. See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions") for more details. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Cc: Josh Poimboeuf Cc: Peter Zijlstra Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250712160103.1244945-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- tools/objtool/check.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index f23bdda737aa..3257eefc41ed 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -224,6 +224,7 @@ static bool is_rust_noreturn(const struct symbol *func) str_ends_with(func->name, "_4core9panicking14panic_explicit") || str_ends_with(func->name, "_4core9panicking14panic_nounwind") || str_ends_with(func->name, "_4core9panicking18panic_bounds_check") || + str_ends_with(func->name, "_4core9panicking18panic_nounwind_fmt") || str_ends_with(func->name, "_4core9panicking19assert_failed_inner") || str_ends_with(func->name, "_4core9panicking30panic_null_pointer_dereference") || str_ends_with(func->name, "_4core9panicking36panic_misaligned_pointer_dereference") || From 7498159226772d66f150dd406be462d75964a366 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sat, 12 Jul 2025 18:01:03 +0200 Subject: [PATCH 3/3] rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails to build the `rusttest` target due to undefined references such as: kernel...-cgu.0:(.text....+0x116): undefined reference to `rust_helper_kunit_get_current_test' Moreover, tooling like `modpost` gets confused: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o The reason behind both issues is that the Rust compiler will now [1] treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`) will be used and that they will be marked as `unique` too, with different IDs. In turn, that means we end up with undefined references that did not get discarded in `rusttest` and that multiple `.modinfo` sections are generated, which confuse tooling like `modpost` because they only expect one. Thus start using `#[used(compiler)]` to keep the previous behavior and to be explicit about what we want. Sadly, it is an unstable feature (`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good news is that it has been available for a long time (Rust >= 1.60) [3]. The changes should also be fine for previous Rust versions, since they behave the same way as before [4]. Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]` since those still behave like `#[used(compiler)]`, but of course it is not really what we want to express, and it requires other changes to avoid symbol conflicts. Cc: David Wood Cc: Wesley Wiser Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: https://github.com/rust-lang/rust/pull/140872 [1] Link: https://github.com/rust-lang/rust/issues/93798 [2] Link: https://github.com/rust-lang/rust/pull/91504 [3] Link: https://godbolt.org/z/sxzWTMfzW [4] Reviewed-by: Alice Ryhl Acked-by: Björn Roy Baron Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/Makefile | 1 + rust/kernel/firmware.rs | 2 +- rust/kernel/kunit.rs | 2 +- rust/kernel/lib.rs | 3 +++ rust/macros/module.rs | 10 +++++----- scripts/Makefile.build | 3 ++- 6 files changed, 13 insertions(+), 8 deletions(-) diff --git a/rust/Makefile b/rust/Makefile index 27dec7904c3a..115b63b7d1e3 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -194,6 +194,7 @@ quiet_cmd_rustdoc_test = RUSTDOC T $< RUST_MODFILE=test.rs \ OBJTREE=$(abspath $(objtree)) \ $(RUSTDOC) --test $(rust_common_flags) \ + -Zcrate-attr='feature(used_with_arg)' \ @$(objtree)/include/generated/rustc_cfg \ $(rustc_target_flags) $(rustdoc_test_target_flags) \ $(rustdoc_test_quiet) \ diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index 2494c96e105f..4fe621f35716 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -202,7 +202,7 @@ macro_rules! module_firmware { }; #[link_section = ".modinfo"] - #[used] + #[used(compiler)] static __MODULE_FIRMWARE: [u8; $($builder)*::create(__MODULE_FIRMWARE_PREFIX) .build_length()] = $($builder)*::create(__MODULE_FIRMWARE_PREFIX).build(); }; diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 4b8cdcb21e77..b9e65905e121 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -302,7 +302,7 @@ macro_rules! kunit_unsafe_test_suite { is_init: false, }; - #[used] + #[used(compiler)] #[allow(unused_unsafe)] #[cfg_attr(not(target_os = "macos"), link_section = ".kunit_test_suites")] static mut KUNIT_TEST_SUITE_ENTRY: *const ::kernel::bindings::kunit_suite = diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 6b4774b2b1c3..e13d6ed88fa6 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -34,6 +34,9 @@ // Expected to become stable. #![feature(arbitrary_self_types)] // +// To be determined. +#![feature(used_with_arg)] +// // `feature(derive_coerce_pointee)` is expected to become stable. Before Rust // 1.84.0, it did not exist, so enable the predecessor features. #![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))] diff --git a/rust/macros/module.rs b/rust/macros/module.rs index 2ddd2eeb2852..75efc6eeeafc 100644 --- a/rust/macros/module.rs +++ b/rust/macros/module.rs @@ -57,7 +57,7 @@ impl<'a> ModInfoBuilder<'a> { {cfg} #[doc(hidden)] #[cfg_attr(not(target_os = \"macos\"), link_section = \".modinfo\")] - #[used] + #[used(compiler)] pub static __{module}_{counter}: [u8; {length}] = *{string}; ", cfg = if builtin { @@ -249,7 +249,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { // key or a new section. For the moment, keep it simple. #[cfg(MODULE)] #[doc(hidden)] - #[used] + #[used(compiler)] static __IS_RUST_MODULE: () = (); static mut __MOD: ::core::mem::MaybeUninit<{type_}> = @@ -273,7 +273,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { #[cfg(MODULE)] #[doc(hidden)] - #[used] + #[used(compiler)] #[link_section = \".init.data\"] static __UNIQUE_ID___addressable_init_module: unsafe extern \"C\" fn() -> i32 = init_module; @@ -293,7 +293,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { #[cfg(MODULE)] #[doc(hidden)] - #[used] + #[used(compiler)] #[link_section = \".exit.data\"] static __UNIQUE_ID___addressable_cleanup_module: extern \"C\" fn() = cleanup_module; @@ -303,7 +303,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { #[cfg(not(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS))] #[doc(hidden)] #[link_section = \"{initcall_section}\"] - #[used] + #[used(compiler)] pub static __{ident}_initcall: extern \"C\" fn() -> ::kernel::ffi::c_int = __{ident}_init; diff --git a/scripts/Makefile.build b/scripts/Makefile.build index a6461ea411f7..ba71b27aa363 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -312,10 +312,11 @@ $(obj)/%.lst: $(obj)/%.c FORCE # - Stable since Rust 1.82.0: `feature(asm_const)`, `feature(raw_ref_op)`. # - Stable since Rust 1.87.0: `feature(asm_goto)`. # - Expected to become stable: `feature(arbitrary_self_types)`. +# - To be determined: `feature(used_with_arg)`. # # Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on # the unstable features in use. -rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op +rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op,used_with_arg # `--out-dir` is required to avoid temporaries being created by `rustc` in the # current working directory, which may be not accessible in the out-of-tree