Re: [PATCH v2] aarch64: Add support for GNU indirect functions.

[Jiong Wang <jiong dot wang at foss dot arm dot com>]

On 27/09/13 10:39, Will Newton wrote:
> Add support for STT_GNU_IFUNC symbols to the AArch64 bfd backend. The 
tests
> are ported from the ld-ifunc tests but are enabled for cross builds 
so can
> be run easily without hardware or a simulator.
>
> This version of the patch uses two passes over the symbols to ensure that
> the dynamic relocs are output in the correct order.
>
>
>     (elfNN_aarch64_allocate_ifunc_dynrelocs): New function.
>     (elfNN_aarch64_allocate_local_ifunc_dynrelocs): New function.
>
>
>   /* This is the most important function of all . Innocuosly named
>      though !  */
> @@ -5987,6 +6421,20 @@ elfNN_aarch64_size_dynamic_sections (bfd 
*output_bfd ATTRIBUTE_UNUSED,
>     elf_link_hash_traverse (&htab->root, 
elfNN_aarch64_allocate_dynrelocs,
>                 info);
>
> +  /* Allocate global ifunc sym .plt and .got entries, and space for 
global
> +     ifunc sym dynamic relocs.  */
> +  elf_link_hash_traverse (&htab->root, 
elfNN_aarch64_allocate_ifunc_dynrelocs,
> +              info);
> +
> +  /* Allocate .plt and .got entries, and space for local symbols.  */
> +  htab_traverse (htab->loc_hash_table,
> +         elfNN_aarch64_allocate_local_dynrelocs,
> +         info);
> +
> +  /* Allocate .plt and .got entries, and space for local ifunc 
symbols.  */
> +  htab_traverse (htab->loc_hash_table,
> +         elfNN_aarch64_allocate_local_ifunc_dynrelocs,
> +         info);

Hi Will,

  I came across above code where extra traverses are introduced for 
IFUNC symbol, any particular
  reason we need them? purely to make sure IFUNC runtime relocations 
happens last? If it is, I
  noticed you are using next_jump_slot_index/next_irelative_index 
mechanism to solve the relocation
  order issue in your initial aarch64 IFUNC support, why it's dropped 
in your final version?

  thanks.

Regards,
Jiong