Re: [RFA 2/5] Darwin: Handle unrelocated dyld.

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2018-08-22 06:11, Xavier Roirand wrote:
> @@ -558,6 +600,56 @@ darwin_solib_create_inferior_hook (int from_tty)
>        if (vmaddr != load_addr)
>  	objfile_rebase (symfile_objfile, load_addr - vmaddr);
>      }
> +
> +  /* Set solib notifier (to reload list of shared libraries).  */
> +  notifier = info->all_image.notifier;
> +  info->notifier_set = 1;
> +
> +  if (info->all_image.count == 0)
> +    {
> +      CORE_ADDR start;
> +
> +      /* Dyld hasn't yet relocated itself, so the notifier address may 
> be
> +        incorrect (as it has to be relocated).
> +        (Apparently dyld doesn't need to relocate itself on x86-64 
> darwin,
> +        but don't assume that).
> +        Set an event breakpoint at the entry point.  */
> +      start = bfd_get_start_address (exec_bfd);
> +      if (start == 0)
> +       notifier = 0;
> +      else
> +        {
> +          gdb_bfd_ref_ptr dyld_bfd (darwin_get_dyld_bfd ());
> +          if (dyld_bfd != NULL)
> +            {
> +              CORE_ADDR dyld_bfd_start_address;
> +              CORE_ADDR dyld_relocated_base_address;
> +              CORE_ADDR pc;
> +
> +              dyld_bfd_start_address = bfd_get_start_address 
> (dyld_bfd.get());
> +
> +              /* We find the dynamic linker's base address by 
> examining
> +                 the current pc (which should point at the entry point
> +                 for the dynamic linker) and subtracting the offset of
> +                 the entry point.  */
> +
> +              pc = regcache_read_pc (get_current_regcache ());
> +              dyld_relocated_base_address = pc - 
> dyld_bfd_start_address;
> +
> +              /* We get the proper notifier relocated address by
> +                 adding the dyld relocated base address to the current
> +                 notifier offset value.  */
> +
> +              notifier += dyld_relocated_base_address;
> +              info->notifier_set = 0;
> +            }
> +        }
> +    }
> +
> +  /* Add the breakpoint which is hit by dyld when the list of solib is
> +     modified.  */
> +  if (notifier != 0)
> +    create_solib_event_breakpoint (target_gdbarch (), notifier);
>  }

Also, if the process of finding the notifier address fails at any point, 
could we display a warning?

Simon