RE: [PATCH v3 3/3] btrace, vdso: add vdso target sections

["Metzger, Markus T" <markus dot t dot metzger at intel dot com>]

Hi Pedro,

I sent this as a patch:
https://sourceware.org/ml/gdb-patches/2014-06/msg00148.html

There's also another patch series open that fixes an assertion when
generating a core file while replaying:
https://sourceware.org/ml/gdb-patches/2014-05/msg00537.html
https://sourceware.org/ml/gdb-patches/2014-05/msg00539.html
https://sourceware.org/ml/gdb-patches/2014-05/msg00538.html

regards,
markus.

> -----Original Message-----
> From: Metzger, Markus T
> Sent: Monday, June 2, 2014 2:41 PM
> To: Pedro Alves
> Cc: gdb-patches@sourceware.org
> Subject: RE: [PATCH v3 3/3] btrace, vdso: add vdso target sections
> 
> > -----Original Message-----
> > From: Pedro Alves [mailto:palves@redhat.com]
> > Sent: Thursday, May 29, 2014 7:04 PM
> 
> 
> > Hmm, wait, nothing is removing the vdso symbols target sections, like ever,
> > not even when the process dies, isn't it?  I guess that's it.
> 
> Yes, that seems to be it.
> 
> Target sections are typically owned by an so_list object and are removed
> when the so_list object is removed.
> 
> Symfile target sections are owned by an objfile object and are removed
> in a free_objfile observer in symfile.c.  That observer only removes target
> sections for OBJF_USERLOADED objfiles, though.
> 
> The vdso target sections are owned by the vdso BFD and are never removed.
> 
> When I change symfile_add_from_memory to create target sections like
> this:
> 
> 	add_target_sections_of_objfile (objf);
> 
> and further drop the restriction to only remove OBJF_USERLOADED objfiles
> in
> symfile_free_objfile, the test passes.
> 
> diff --git a/gdb/symfile-mem.c b/gdb/symfile-mem.c
> index b29421e..ef48f7d 100644
> --- a/gdb/symfile-mem.c
> +++ b/gdb/symfile-mem.c
> @@ -92,7 +92,6 @@ symbol_file_add_from_memory (struct bfd *templ,
> CORE_ADDR addr,
>    struct section_addr_info *sai;
>    unsigned int i;
>    struct cleanup *cleanup;
> -  struct target_section *sections, *sections_end, *tsec;
> 
>    if (bfd_get_flavour (templ) != bfd_target_elf_flavour)
>      error (_("add-symbol-file-from-memory not supported for this target"));
> @@ -132,22 +131,7 @@ symbol_file_add_from_memory (struct bfd *templ,
> CORE_ADDR addr,
>                                    from_tty ? SYMFILE_VERBOSE : 0,
>                                     sai, OBJF_SHARED, NULL);
> 
> -  sections = NULL;
> -  sections_end = NULL;
> -
> -  if (build_section_table (nbfd, &sections, &sections_end) == 0)
> -    {
> -      make_cleanup (xfree, sections);
> -
> -      /* Adjust the target section addresses by the load address.  */
> -      for (tsec = sections; tsec != sections_end; ++tsec)
> -       {
> -         tsec->addr += loadbase;
> -         tsec->endaddr += loadbase;
> -       }
> -
> -      add_target_sections (&nbfd, sections, sections_end);
> -    }
> +  add_target_sections_of_objfile (objf);
> 
>    /* This might change our ideas about frames already looked at.  */
>    reinit_frame_cache ();
> diff --git a/gdb/symfile.c b/gdb/symfile.c
> index 64a83c6..caa0722 100644
> --- a/gdb/symfile.c
> +++ b/gdb/symfile.c
> @@ -3893,7 +3893,7 @@ static void
>  symfile_free_objfile (struct objfile *objfile)
>  {
>    /* Remove the target sections of user-added objfiles.  */
> -  if (objfile != 0 && objfile->flags & OBJF_USERLOADED)
> +  if (objfile != NULL)
>      remove_target_sections ((void *) objfile);
>  }
> 
> Alternatively, I could add another OBJF_ flag and another free_objfile
> observer
> to also remove the symfile-from-memory target sections.
> 
> Regards,
> Markus.

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