From 993f235c4af49d0e912cc28abe6d733531600237 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Wed, 5 Aug 2026 16:45:24 +0200 Subject: objtool/rust: add one more `noreturn` Rust function When the pointer formatting series [1] is applied and KUnit tests are enabled, `objtool` would report an error with any of our supported Rust versions. For instance, with Rust 1.97.1: rust/kernel.o: error: objtool: _R..._4core3fmt7Pointer3fmtB7_() falls through to next function _R..._4core7convert5AsRefNtB5_4BStrE6as_ref() Or, with Rust 1.85.0: rust/kernel.o: error: objtool: _R..._4core3fmt7Pointer3fmtB7_() falls through to next function _R..._4core3ffi5c_str4CStrENtNtBS_3fmt7Display3fmtB7_() This happens due to calls to the `noreturn` symbol: core::str::slice_error_fail 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. [ While the series [1] mentioned above was not applied in a way that triggered this, Gary found another case [2]: I am seeing this function causing issue on my 1.85.1 -Os build, although the error message is different this time: rust/kernel.o: warning: objtool: _R..._5range9RangeFromjEE5indexCsldbe0TGTmNx_6kernel+0x1d: stack state mismatch: cfa1=4+8 cfa2=4+16 Disassembly shows that the function call before the warning location is a call to _4core3str16slice_error_fail, and objtool thought it can return (which will end up with a unbalanced stack if it does return). Thus apply it. - Miguel ] Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Cc: Josh Poimboeuf Cc: Peter Zijlstra Reported-by: Alice Ryhl Link: https://lore.kernel.org/rust-for-linux/anLxXvCKBcAVf91_@google.com/ Link: https://lore.kernel.org/rust-for-linux/20260706-hashedptr-v13-0-377a07f2f78d@kylinos.cn/ [1] Link: https://lore.kernel.org/rust-for-linux/DKS7U9UHY6XR.2JC0EBIPCI06Z@garyguo.net/ [2] Link: https://patch.msgid.link/20260805144524.233362-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- tools/objtool/check.c | 1 + 1 file changed, 1 insertion(+) (limited to 'tools/objtool') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 87db9f4ed9e2..3ab5b9f1c6a4 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -195,6 +195,7 @@ static bool is_rust_noreturn(const struct symbol *func) return str_ends_with(func->name, "_4core3num20from_str_radix_panic") || str_ends_with(func->name, "_4core3num22from_ascii_radix_panic") || str_ends_with(func->name, "_4core3num28from_ascii_bytes_radix_panic") || + str_ends_with(func->name, "_4core3str16slice_error_fail") || str_ends_with(func->name, "_4core5sliceSp15copy_from_slice17len_mismatch_fail") || str_ends_with(func->name, "_4core6option13expect_failed") || str_ends_with(func->name, "_4core6option13unwrap_failed") || -- cgit