Re: [committed] MIPS/BFD: Respect the ELF gABI dynamic symbol table sort requirement

["Maciej W. Rozycki" <macro at imgtec dot com>]

On Thu, 2 Feb 2017, Maciej W. Rozycki wrote:

> Ensure all local symbols precede external symbols in the dynamic symbol 
> table.
> 
> No local symbols are expected to make it to the dynamic symbol table 
> except for section symbols already taken care of, so this is really a 
> safeguard only against a potential BFD bug otherwise not so harmful, 
> which may become a grave one due to a symbol table sorting requirement 
> violation (see PR ld/20828 for an example).  This means however that no 
> test suite coverage is possible for this change as code introduced here 
> is not normally expected to trigger.
> 
> Logically split then the part of the dynamic symbol table which is not 
> global offset table mapped, into a local area at the beginning and an 
> external area following.  By the time `mips_elf_sort_hash_table' is 
> called we have the number of local dynamic symbol table entries (section 
> and non-section) already counted in `local_dynsymcount', so use it to 
> offset the external area from the beginning.
> 
> 	bfd/
> 	* elfxx-mips.c (mips_elf_hash_sort_data): Add 
> 	`max_local_dynindx'.
> 	(mips_elf_sort_hash_table): Handle it.
> 	(mips_elf_sort_hash_table_f) <GGA_NONE>: For forced local 
> 	symbols bump up `max_local_dynindx' rather than 
> 	`max_non_got_dynindx'.
> ---

 I have been told the issue outstanding with PR ld/20828 and version 
symbols causes non-working executables to be produced such as in the case 
of Firefox.

 I have therefore decided to backport this change (and its 3 preparatory 
cleanups) to 2.28 to make people's life easier, as it makes executables 
work while not making them otherwise any worse than now -- the binding of 
any version symbols remains local, which is incorrect, or at least 
inconsistent, however very unlikely to cause any problem.

  Maciej