linux-kernel - [PATCH 1/5] objtool/rust: add one more `noreturn` Rust function for Rust 1.87.0

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Message-ID: <20250502140237.1659624-2-ojeda@kernel.org>
Date: Fri,  2 May 2025 16:02:33 +0200
From: Miguel Ojeda <ojeda@...nel.org>
To: Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>
Cc: Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>,
	rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	stable@...r.kernel.org,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 1/5] objtool/rust: add one more `noreturn` Rust function for Rust 1.87.0

Starting with Rust 1.87.0 (expected 2025-05-15), `objtool` may report:

    rust/core.o: warning: objtool: _R..._4core9panicking9panic_fmt() falls
    through to next function _R..._4core9panicking18panic_nounwind_fmt()

    rust/core.o: warning: objtool: _R..._4core9panicking18panic_nounwind_fmt()
    falls through to next function _R..._4core9panicking5panic()

The reason is that `rust_begin_unwind` is now mangled:

    _R..._7___rustc17rust_begin_unwind

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.

Alternatively, we could remove the fixed one in `noreturn.h` and relax
this test to cover both, but it seems best to be strict as long as we can.

Cc: stable@...r.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Cc: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
---
 tools/objtool/check.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3a411064fa34..b21b12ec88d9 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -227,6 +227,7 @@ static bool is_rust_noreturn(const struct symbol *func)
 	       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")	||
+	       str_ends_with(func->name, "_7___rustc17rust_begin_unwind")				||
 	       strstr(func->name, "_4core9panicking13assert_failed")					||
 	       strstr(func->name, "_4core9panicking11panic_const24panic_const_")			||
 	       (strstr(func->name, "_4core5slice5index24slice_") &&
--
2.49.0