objtool/rust: add one more noreturn Rust function

JIRA: https://issues.redhat.com/browse/RHEL-114921

commit dbdf2a7
Author: Miguel Ojeda <ojeda@kernel.org>
Date:   Mon Oct 20 04:07:14 2025 +0200

    objtool/rust: add one more `noreturn` Rust function

    Between Rust 1.79 and 1.86, under `CONFIG_RUST_KERNEL_DOCTESTS=y`,
    `objtool` may report:

        rust/doctests_kernel_generated.o: warning: objtool:
        rust_doctest_kernel_alloc_kbox_rs_13() falls through to next
        function rust_doctest_kernel_alloc_kvec_rs_0()

    (as well as in rust_doctest_kernel_alloc_kvec_rs_0) due to calls to the
    `noreturn` symbol:

        core::option::expect_failed

    from code added in commits 779db37 ("rust: alloc: kvec: implement
    AsPageIter for VVec") and 6716184 ("rust: alloc: kbox: implement
    AsPageIter for VBox").

    Thus add the mangled one to the list so that `objtool` knows it is
    actually `noreturn`.

    This can be reproduced as well in other versions by tweaking the code,
    such as the latest stable Rust (1.90.0).

    Stable does not have code that triggers this, but it could have it in
    the future. Downstream forks could too. Thus tag it for backport.

    See commit 56d680d ("objtool/rust: list `noreturn` Rust functions")
    for more details.

    Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Reviewed-by: Alice Ryhl <aliceryhl@google.com>
    Cc: stable@vger.kernel.org # Needed in 6.12.y and later.
    Link: https://patch.msgid.link/20251020020714.2511718-1-ojeda@kernel.org

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>

Author: joe-lawrence

tools/objtool/check.c

@@ -218,6 +218,7 @@ static bool is_rust_noreturn(const struct symbol *func)
 	 * these come from the Rust standard library).
 	 */
 	return str_ends_with(func->name, "_4core5sliceSp15copy_from_slice17len_mismatch_fail")		||
+	       str_ends_with(func->name, "_4core6option13expect_failed")				||
 	       str_ends_with(func->name, "_4core6option13unwrap_failed")				||
 	       str_ends_with(func->name, "_4core6result13unwrap_failed")				||
 	       str_ends_with(func->name, "_4core9panicking5panic")					||