From: Peter Zijlstra <peterz@infradead.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Sergio González Collado" <sergio.collado@gmail.com>,
"Brendan Higgins" <brendan.higgins@linux.dev>,
"David Gow" <davidgow@google.com>,
"Miguel Ojeda" <ojeda@kernel.org>,
"Alex Gaynor" <alex.gaynor@gmail.com>,
linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
"Dave Hansen" <dave.hansen@linuax.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Josh Poimboeuf" <jpoimboe@kernel.org>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Benno Lossin" <benno.lossin@proton.me>,
"Andreas Hindborg" <a.hindborg@samsung.com>,
"Alice Ryhl" <aliceryhl@google.com>,
"David Rheinsberg" <david@readahead.eu>,
rust-for-linux@vger.kernel.org, skhan@linuxfoundation.org,
ricardo.marliere@suse.com, "Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Martin Rodriguez Reboredo" <yakoyoku@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: Symbol too long for allsyms warnings on KSYM_NAME_LEN
Date: Thu, 27 Mar 2025 14:58:47 +0100 [thread overview]
Message-ID: <20250327135847.GE31358@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <66f3f697-530a-4d22-979a-1472c8e8de3a@app.fastmail.com>
On Thu, Mar 27, 2025 at 09:38:46AM +0100, Arnd Bergmann wrote:
> My randconfig builds sometimes (around one in every 700 configs) run
> into this warning on x86:
>
> Symbol __pfx_snnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7n too long for kallsyms (517 >= 512).
> Please increase KSYM_NAME_LEN both in kernel and kallsyms.c
>
> The check that gets triggered was added in commit c104c16073b
> ("Kunit to check the longest symbol length"), see
> https://lore.kernel.org/all/20241117195923.222145-1-sergio.collado@gmail.com/
>
> and the overlong identifier seems to be the result of objtool adding
> the six-byte "__pfx_" string to a symbol in elf_create_prefix_symbol()
> when CONFIG_FUNCTION_PADDING_CFI is set.
>
> I think the suggestion to "Please increase KSYM_NAME_LEN both in
> kernel and kallsyms.c" is misleading here and should probably be
> changed. I don't know if this something that objtool should work
> around, or something that needs to be adapted in the test.
Probably test needs to be fixed; objtool can't really do anything here,
it just take the existing symname and prefixes it.
next prev parent reply other threads:[~2025-03-27 13:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-27 8:38 Symbol too long for allsyms warnings on KSYM_NAME_LEN Arnd Bergmann
2025-03-27 13:58 ` Peter Zijlstra [this message]
2025-03-28 11:23 ` Arnd Bergmann
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