Re: Weird relocations

[Ian Lance Taylor <ian at zembu dot com>]

   From: Toshi Morita <tm2@best.com>
   Date: Fri, 24 Sep 1999 16:16:36 -0700 (PDT)

   When this code in bfd/elf32-sh.c is executed:

	 r_symndx = ELF32_R_SYM (rel->r_info);
   ...
	 if (r_symndx < symtab_hdr->sh_info)
	   {
	     /* There is nothing to be done for an internal IND12W
		relocation.  FIXME: This is probably wrong, but it's how
		the COFF relocations work.  */
	     if (r_type == (int) R_SH_IND12W)
	       continue;
	     sym = local_syms + r_symndx;
	     sec = local_sections[r_symndx];
	     relocation = (sec->output_section->vma
			   + sec->output_offset
			   + sym->st_value);
	   }

   the pointer "sec" is assigned a null value because r_symndex seems
   to be invalid (when run in the debugger).

This is specifically testing for the case of a local symbol.  r_symndx
may have been invalid, but it's not invalid for it to be larger than
symtab_hdr->sh_info; that just means the relocation is not against a
local symbol.

   When I go dump out the relocations of that object file with sh-elf-objdump
   --reloc, I see some suspicious relocations:

   RELOCATION RECORDS FOR [.debug]:
   OFFSET   TYPE              VALUE
   00000008 R_SH_DIR32        .debug
   00000053 R_SH_DIR32        .text
   00000059 R_SH_DIR32        .text
   0000005f R_SH_DIR32        .line
   0000007c R_SH_DIR32        .debug_sfnames
   00000082 R_SH_DIR32        .debug_srcinfo
   0000008e R_SH_DIR32        .debug
   000000b4 R_SH_DIR32        .debug
   000000d9 R_SH_DIR32        .debug
   ...
   0000b516 R_SH_DIR32        .debug
   0000b51c R_SH_DIR32        .debug
   0000b522 R_SH_DIR32        _bSqrt__Ff		<- here
   0000b528 R_SH_DIR32        .L_f301_e		<- here
   0000b52e R_SH_DIR32        .L_b301		<- here
   0000b534 R_SH_DIR32        .L_b301_e		<- here

   These relocations seems suspicious because all the other entries in the "VALUE"
   field are names of sections, but these three are label names... and they are
   also the relocations which are not properly applied.

   Am I correct in assuming the "VALUE" field of a .debug relocation should
   always contain a reference to a section, and not a label? And if so,
   are these relocations clearly incorrect?

It's OK for a .debug relocation to refer to a symbol, and I would
expect it in cases involving a global symbol.

I don't know why you are seeing relocations against symbols named .L*.
I wonder whether you have this patch in your sources:

1999-06-13  Ian Lance Taylor  <ian@zembu.com>

	* write.c (adjust_reloc_syms): Rather than never reducing reloc
	which refer to symbols in linkonce sections, permit reducing the
	relocs if the symbol is local.

As you can see, this again leads me to think about linkonce sections.
In what section are those symbols actually defined?

Ian