[PATCH] elf: Fix tst-gnu2-tls2 on some environments

[Adhemerval Zanella Netto]

On 19/01/26 13:24, Florian Weimer wrote:
> * Adhemerval Zanella Netto:
> 
>> On 19/01/26 12:18, Florian Weimer wrote:
>>> * Adhemerval Zanella Netto:
>>>
>>>> On 19/01/26 11:22, Florian Weimer wrote:
>>>>> * Adhemerval Zanella:
>>>>>
>>>>>> On armv7a vfpv4 tst-gnu2-tls2 fails with:
>>>>>>
>>>>>>   open tst-gnu2-tls2mod0.so
>>>>>>   open tst-gnu2-tls2mod1.so
>>>>>>   open tst-gnu2-tls2mod2.so
>>>>>>   close tst-gnu2-tls2mod0.so
>>>>>>   close tst-gnu2-tls2mod1.so
>>>>>>   open tst-gnu2-tls2mod0.so
>>>>>>   open tst-gnu2-tls2mod1.so
>>>>>>   Didn't expect signal from child: got `Aborted'
>>>>>>
>>>>>> Because AFTER_TLSDESC_CALL might clobber caller-saved registers and
>>>>>> the zero array might call the memset function resolution, which itself
>>>>>> might clobber some vector registers.
>>>>>
>>>>> Isn't AFTER_TLSDESC_CALL a noop on 32-bit Arm
>>>>
>>>> It depends on the hardware, with HWCAP_ARM_VFP we checks if d0-d15 register
>>>> are correctly handled, and with HWCAP_ARM_VFPD32 with also check d16-d31.
>>>
>>> What does the ABI say about preserving vector registers?
> 
>> This is related to 64c7e344289ed085517c2227d8e3b06388242c13, where
>> _dl_tlsdesc_dynamic slow-path has the peculiar calling convention.
> 
> Ah, so the test is somewhat invalid because it assumes that memset et
> al. do not clobber vector registers?
> 
> Maybe add a comment to that effect to AFTER_TLSDESC_CALL, and mention
> the need for BIND_NOW.

Fair enough, I will add a comment.