Re: [PATCH] nptl: fix potential merge of __rseq_* relro symbols

[Michael Jeanson <mjeanson@efficios.com>]

On 2024-01-15 16:34, Michael Jeanson wrote:
> On 2024-01-15 16:20, H.J. Lu wrote:
>>> +/* Due to the use of '-fmerge-all-constants' the compiler is allowed to merge
>>> +   all 'const' variables of the same size that are initialized to the same
>>> +   value.  To work around this, declare them as regular static variable 
>>> and use
>>> +   an alias that is 'const'.  */
>>> +static unsigned int rseq_size attribute_relro;
>>> +extern const unsigned int __attribute__ ((alias ("rseq_size"))) __rseq_size;
>>> +static ptrdiff_t rseq_offset attribute_relro;
>>> +extern const ptrdiff_t __attribute__ ((alias ("rseq_offset"))) __rseq_offset;
>>
>> Don't you want to mark them as hidden if they are internal to glibc?
> 
> Indeed, the static variables should be hidden, I thought the build system was 
> setup to make them by default, I'll send a v2.

I answered this one too quickly, the 'static' symbols rseq_size and 
rseq_offset are hidden which is okay and the alias symbols __rseq_size and 
__rseq_offset are public and part of the API/ABI since 2.35.

Michael