Re: ld assertion failures building NetBSD-VAX with GCC 4.5

[christos%astron.com@localhost (Christos Zoulas)]

In article 
<CABfdNnQVboMjPokQ4zD5Kt4HnpxkMW4RO8G+uRu2uzZbvX8KHQ%mail.gmail.com@localhost>,
Jake Hamby  <jake.hamby%gmail.com@localhost> wrote:
>I have a patch to binutils that fixes the ld assertion failure with
>GCC 4.5. I haven't tested the generated code yet, but I will do that
>tonight.
>
>The cause was that "__clz_tab" and "__popcount_tab" are defined in
>libgcc.a with the hidden attribute in GCC 4.5 but not in GCC 4.1. The
>hidden attribute is not defined in the code but is added to the
>symbols in the .o files with some special rules in
>external/gpl3/gcc/lib/libgcc/libgcc/Makefile.
>
>The bug is that elf_vax_instantiate_got_entries() in elf32-vax.c
>doesn't allocate space in the .got and .rela.got sections for the
>hidden symbols because it only does so if the visibility is set to
>default. For the two hidden symbols, this isn't the case. There's a
>section of code in elf_vax_relocate_section() immediately after I was
>seeing the assertion failure that has special handling that applies to
>these cases:
>
>            dyn = elf_hash_table (info)->dynamic_sections_created;
>            if (! WILL_CALL_FINISH_DYNAMIC_SYMBOL (dyn, info->shared, h)
>                || (info->shared
>                    && SYMBOL_REFERENCES_LOCAL (info, h)))
>              {
>                /* The symbol was forced to be local
>                   because of a version file..  We must initialize
>                   this entry in the global offset table.  Since
>                   the offset must always be a multiple of 4, we
>                   use the least significant bit to record whether
>                   we have initialized it already.
>
>                   When doing a dynamic link, we create a .rela.got
>                   relocation entry to initialize the value.  This
>                   is done in the finish_dynamic_symbol routine.  */
>
>I modified the check in elf_vax_instantiate_got_entries() to also
>reserve space when WILL_CALL_FINISH_DYNAMIC_SYMBOL() returns false,
>which only happens for the two hidden symbols in the entire NetBSD
>build. The assertion failures happened when an executable like "vi" or
>"less" referenced either __clz_tab or __popcount_tab, which got pulled
>in from libgcc.a and then the GOT table was one entry too small
>because a slot was reserved but the size wasn't incremented. Here's my
>patch, which also updates a few comments to note that there are 3, not
>2, reserved entries in the GOT.
>
>--- external/gpl3/binutils/dist/bfd/elf32-vax.c 3 Sep 2012 18:59:23
>-0000 1.5.2.2
>+++ external/gpl3/binutils/dist/bfd/elf32-vax.c 13 Mar 2013 00:38:28 -0000
>@@ -1337,8 +1337,7 @@
>       dyn = elf_hash_table (info)->dynamic_sections_created;
>       /* Allocate space in the .got and .rela.got sections.  */
>       if (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
>-  && (info->shared
>-      || WILL_CALL_FINISH_DYNAMIC_SYMBOL (dyn, 0, h)))
>+  || !WILL_CALL_FINISH_DYNAMIC_SYMBOL (dyn, 0, h))
>  {
>   sgot->size += 4;
>   srelgot->size += sizeof (Elf32_External_Rela);
>@@ -1572,7 +1571,7 @@
>
>   /* Get the offset into the .got table of the entry that
>      corresponds to this function.  Each .got entry is 4 bytes.
>-     The first two are reserved.  */
>+     The first three are reserved.  */
>   got_offset = (plt_index + 3) * 4;
>
>   /* We want the relocation to point into the .got.plt instead
>@@ -1839,7 +1838,7 @@
>
>       /* Get the offset into the .got table of the entry that
>  corresponds to this function.  Each .got entry is 4 bytes.
>- The first two are reserved.  */
>+ The first three are reserved.  */
>       got_offset = (plt_index + 3) * 4;
>
>       /* Fill in the entry in the procedure linkage table.  */
>
>
>Hopefully the whitespace didn't get borked when I pasted that.

Excellent. Please let us know how it goes!

christos