Rust fixes for v6.16 (2nd)

Toolchain and infrastructure:
 
  - Fix build and modpost confusion for the upcoming Rust 1.89.0 release.
 
  - Clean objtool warning for the upcoming Rust 1.89.0 release by adding
    one more noreturn function.
 
 'kernel' crate:
 
  - Fix build error when using generics in the 'try_{,pin_}init!' macros.
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Merge tag 'rust-fixes-6.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

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

   - Fix build and modpost confusion for the upcoming Rust 1.89.0
     release

   - Clean objtool warning for the upcoming Rust 1.89.0 release by
     adding one more noreturn function

  'kernel' crate:

   - Fix build error when using generics in the 'try_{,pin_}init!'
     macros"

* tag 'rust-fixes-6.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
  rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0
  objtool/rust: add one more `noreturn` Rust function for Rust 1.89.0
  rust: init: Fix generics in *_init! macros

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) \

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();
         };

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)
     };

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 =

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))]

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;
 

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

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")	||