Re: Re: GNU strip fails to set sh_link and sh_info on Solaris SPARC64

[Libor Bukata]

Hi Nick,

On 3/1/21 4:00 PM, Nick Clifton wrote:
> Hi Libor,
>
> > I noticed that GNU strip produced invalid binaries on SPARC 64, the 
> > reason is that bfd/elf64-sparc.c was not updated in 
> > https://urldefense.com/v3/__https://sourceware.org/bugzilla/show_bug.cgi?id=19938__;!!GqivPVa7Brio!LHjGCJnVDPytceZx1EmUuq933MqeYYHre-566VGSbPbdFKi-HjG8enRG0VyslmNuWw$ 
> > issue.
> >
> > The attached patch just follows Nick Clifton's changes for other 
> > architectures.
>
> Patch approved - please apply.
thank you for your approval. How can I obtain a write permission to 
binutils repository?
> > Note that .SUNW_symtabsort, .SUNW_symtabnsort, and .SUNW_symtlssort 
> > sections refer to .symtab section, therefore, if .symtab is removed, 
> > theses sections should be skipped in copy as well. However, I am not 
> > sure how to properly implement it, maybe use 
> > handle_remove_section_option if the number of symbols is zero?
>
> That should probably work.  If you have the time, please could you 
> give it a try.
I tried the following code:
--- binutils-2.35.1/binutils/objcopy.c  2021-03-01 07:54:25.600752820 +0000
+++ binutils-2.35.1/binutils/objcopy.c  2021-03-01 07:53:48.447749729 +0000
@@ -2579,6 +2579,9 @@ check_new_section_flags (flagword flags,
   return flags;
 }

+static void
+handle_remove_section_option (const char *);
+
 /* Copy object file IBFD onto OBFD.
    Returns TRUE upon success, FALSE otherwise.  */

@@ -3258,6 +3261,13 @@ copy_object (bfd *ibfd, bfd *obfd, const
     }

   bfd_set_symtab (obfd, osympp, symcount);
+  #if defined(sun) || defined(__sun) || defined(__sun__)
+  if (symcount == 0)  {
+    handle_remove_section_option(".SUNW_symtabsort");
+    handle_remove_section_option(".SUNW_symtabnsort");
+    handle_remove_section_option(".SUNW_symtlssort");
+  }
+  #endif

   /* This has to happen before section positions are set.  */
   bfd_map_over_sections (ibfd, copy_relocations_in_section, obfd);


Unfortunately the above code does not work for the following reasons:

- sections are already created in that point of code
- symbol filtering requires output sections to be created
- cannot find bfd_remove_section function that could handle it

I verified that the sections can be removed if requested after argument 
processing:
--- binutils-2.35.1/binutils/objcopy.c  2021-01-29 15:13:12.464152915 +0000
+++ binutils-2.35.1/binutils/objcopy.c  2021-01-29 15:12:55.533627345 +0000
@@ -4748,6 +4748,12 @@ strip_main (int argc, char *argv[])
        }
     }

+  #if defined(sun) || defined(__sun) || defined(__sun__)
+  handle_remove_section_option(".SUNW_symtabsort");
+  handle_remove_section_option(".SUNW_symtabnsort");
+  handle_remove_section_option(".SUNW_symtlssort");
+  #endif
+
   /* If the user has not expressly chosen to merge/not-merge ELF notes
      then enable the merging unless we are stripping debug or dwo 
info.  */
   if (! merge_notes_set


However, this code removes the sections unconditionally regardless of 
whether .symtab is kept or not. I can image that GNU strip could be 
called in two passes: the first pass could remove .symtab and .strtab 
sections; the second pass would strip .SUNW_sym*sort sections if .symtab 
section was stripped in the first pass. A big disadvantage is that it 
introduces double performance overhead... Any ideas?

Thanks,
Libor

> Cheers
>   Nick