Re: [rfc] Fix "step" for ld.so debugging [Re: [RFC] problem in solib-svr4/enable_break]

[Michael Snyder <msnyder@vmware.com>]

Jan Kratochvil wrote:
> Hi Michael,
> 
> I see there is a problem for debugging ld.so even on native GNU/Linux when
> I get some intentional way into the ld.so code.  Existing problem:
> (gdb) frame
> #0  _dl_fixup (l=0x7ffff7ffe0e8, reloc_arg=<value optimized out>) at ../elf/dl-runtime.c:90
> 90	  if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
> (gdb) next
> 94	      if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
> (gdb) next
> 99		  version = &l->l_versions[ndx];
> (gdb) next
> 100		  if (version->hash == 0)
> (gdb) step
> pause () at ../sysdeps/unix/syscall-template.S:82
> 82	T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
> 
> ("next" works but "step" skips whole ld.so resolver)
> 
> Wouldn't the patch below also solve your "PIE kernel" problem?
> 
> No regressions on {x86_64,x86_64-m32,i686}-fedora12-linux-gnu.
> But I am not much sure about some possible regressions with this code.

Jan, thanks, I can see the logic, and it does indeed fix my
symptom.  Are you thinking of checking it in?