Re: bug: GOLD handling of Sparc PLTREL

[David Miller <davem at davemloft dot net>]

From: David Miller <davem@davemloft.net>
Date: Mon, 08 Feb 2010 22:01:21 -0800 (PST)

> # ifdef ELF_MACHINE_PLTREL_OVERLAP
> #  define _ELF_DYNAMIC_DO_RELOC(RELOC, reloc, map, do_lazy, test_rel) \
 ...
> (##RELOC here is RELA)

And for reference here is the code that gets passed those ranges,
from elf/do-rel.h:

auto inline void __attribute__ ((always_inline))
elf_dynamic_do_rel (struct link_map *map,
		    ElfW(Addr) reladdr, ElfW(Addr) relsize,
		    int lazy)
{
  const ElfW(Rel) *r = (const void *) reladdr;
  const ElfW(Rel) *end = (const void *) (reladdr + relsize);
  ElfW(Addr) l_addr = map->l_addr;

#if (!defined DO_RELA || !defined ELF_MACHINE_PLT_REL) && !defined RTLD_BOOTSTRAP
  /* We never bind lazily during ld.so bootstrap.  Unfortunately gcc is
     not clever enough to see through all the function calls to realize
     that.  */
  if (lazy)
    {
      /* Doing lazy PLT relocations; they need very little info.  */
      for (; r < end; ++r)
	elf_machine_lazy_rel (map, l_addr, r);
    }
  else
#endif
    {
      const ElfW(Sym) *const symtab =
	(const void *) D_PTR (map, l_info[DT_SYMTAB]);
      ElfW(Word) nrelative = (map->l_info[RELCOUNT_IDX] == NULL
			      ? 0 : map->l_info[RELCOUNT_IDX]->d_un.d_val);
      const ElfW(Rel) *relative = r;
      r = r + MIN (nrelative, relsize / sizeof (ElfW(Rel)));

#ifndef RTLD_BOOTSTRAP
      /* This is defined in rtld.c, but nowhere in the static libc.a; make
	 the reference weak so static programs can still link.  This
	 declaration cannot be done when compiling rtld.c (i.e. #ifdef
	 RTLD_BOOTSTRAP) because rtld.c contains the common defn for
	 _dl_rtld_map, which is incompatible with a weak decl in the same
	 file.  */
# ifndef SHARED
      weak_extern (GL(dl_rtld_map));
# endif
      if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
# if !defined DO_RELA || defined ELF_MACHINE_REL_RELATIVE
	/* Rela platforms get the offset from r_addend and this must
	   be copied in the relocation address.  Therefore we can skip
	   the relative relocations only if this is for rel
	   relocations or rela relocations if they are computed as
	   memory_loc += l_addr...  */
	if (l_addr != 0)
# else
	/* ...or we know the object has been prelinked.  */
	if (l_addr != 0 || ! map->l_info[VALIDX(DT_GNU_PRELINKED)])
# endif
#endif
	  for (; relative < r; ++relative)
	    DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative);

#ifdef RTLD_BOOTSTRAP
      /* The dynamic linker always uses versioning.  */
      assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL);
#else
      if (map->l_info[VERSYMIDX (DT_VERSYM)])
#endif
	{
	  const ElfW(Half) *const version =
	    (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);

	  for (; r < end; ++r)
	    {
	      ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)] & 0x7fff;
	      elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)],
			       &map->l_versions[ndx],
			       (void *) (l_addr + r->r_offset));
	    }
	}
#ifndef RTLD_BOOTSTRAP
      else
	for (; r < end; ++r)
	  elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL,
			   (void *) (l_addr + r->r_offset));
#endif
    }
}