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objtool/rust: add one more noreturn Rust function

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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 56d680dd23 ("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 <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reported-by: Alice Ryhl <aliceryhl@google.com>
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 <ojeda@kernel.org>
This commit is contained in:
Miguel Ojeda 2026-08-05 16:45:24 +02:00
parent a5c7d35e2f
commit 993f235c4a
1 changed files with 1 additions and 0 deletions
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tools/objtool/check.c
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@ -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") ||