* Symbol too long for allsyms warnings on KSYM_NAME_LEN
@ 2025-03-27 8:38 Arnd Bergmann
2025-03-27 13:58 ` Peter Zijlstra
0 siblings, 1 reply; 3+ messages in thread
From: Arnd Bergmann @ 2025-03-27 8:38 UTC (permalink / raw)
To: Sergio González Collado, Brendan Higgins, David Gow,
Miguel Ojeda, Alex Gaynor, linux-kselftest, kunit-dev,
sergio.collado, Dave Hansen, H. Peter Anvin, Josh Poimboeuf,
Peter Zijlstra
Cc: Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, David Rheinsberg, rust-for-linux,
skhan, ricardo.marliere, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, Martin Rodriguez Reboredo, linux-kernel
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.
Arnd
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Symbol too long for allsyms warnings on KSYM_NAME_LEN
2025-03-27 8:38 Symbol too long for allsyms warnings on KSYM_NAME_LEN Arnd Bergmann
@ 2025-03-27 13:58 ` Peter Zijlstra
2025-03-28 11:23 ` Arnd Bergmann
0 siblings, 1 reply; 3+ messages in thread
From: Peter Zijlstra @ 2025-03-27 13:58 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Sergio González Collado, Brendan Higgins, David Gow,
Miguel Ojeda, Alex Gaynor, linux-kselftest, kunit-dev,
Dave Hansen, H. Peter Anvin, Josh Poimboeuf, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
David Rheinsberg, rust-for-linux, skhan, ricardo.marliere,
Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Martin Rodriguez Reboredo, linux-kernel
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.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Symbol too long for allsyms warnings on KSYM_NAME_LEN
2025-03-27 13:58 ` Peter Zijlstra
@ 2025-03-28 11:23 ` Arnd Bergmann
0 siblings, 0 replies; 3+ messages in thread
From: Arnd Bergmann @ 2025-03-28 11:23 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Sergio González Collado, Brendan Higgins, David Gow,
Miguel Ojeda, Alex Gaynor, linux-kselftest, kunit-dev,
Dave Hansen, H. Peter Anvin, Josh Poimboeuf, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
David Rheinsberg, rust-for-linux, Shuah Khan, ricardo.marliere,
Thomas Gleixner, Ingo Molnar, Borislav Petkov,
Martin Rodriguez Reboredo, linux-kernel
On Thu, Mar 27, 2025, at 14:58, Peter Zijlstra wrote:
> 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.
I found a workaround that avoids the problem for me now, see
https://lore.kernel.org/linux-kbuild/20250328112156.2614513-1-arnd@kernel.org/
Arnd
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-03-27 8:38 Symbol too long for allsyms warnings on KSYM_NAME_LEN Arnd Bergmann
2025-03-27 13:58 ` Peter Zijlstra
2025-03-28 11:23 ` Arnd Bergmann
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