Re: VMA section overlap warnings for overlays

[Alan Modra <amodra at gmail dot com>]

On Sat, Aug 28, 2010 at 06:39:36AM -0700, H.J. Lu wrote:
> On Sat, Aug 28, 2010 at 6:28 AM, Alan Modra <amodra@gmail.com> wrote:
> > The real bug was that copy_elf_program_header calculated header_size
> > from the first section found to be in the segment rather than the
> > section with the lowest lma. ?So a one line fix. ?The rest of this
> > patch is to cope with (and fix) invalid program header p_paddr values.
> 
> There is no such a thing as "invalid program header p_paddr values"
> since ELF spec says it has unspecified contents.

Yes, that's technically true.  My language wasn't precise.  I should
have said inconsistent p_paddr values.

> You can't depend on contents in p_addr in objcopy.

Are you saying that objcopy should throw away all p_paddr values?
That doesn't make sense at all.  Just because the ELF spec doesn't
specify p_paddr, doesn't mean that GNU binutils cannot use p_paddr.
We use p_paddr to record section LMAs, since ELF section headers only
have a field for VMAs.

> > I won't commit this immediately as I'd like to run some more tests.
> >
> > ? ? ? ?PR binutils/11953
> > ? ? ? ?* elf.c (copy_elf_program_header): Calculate map->header_size
> > ? ? ? ?from lowest_section, not first_section. ?Validate program
> > ? ? ? ?header p_paddr against section lma. ?Find lowest_section in
> > ? ? ? ?second loop over headers.
> >
> 
> Can we not look at p_addr here?

I don't know what you mean by that question.

-- 
Alan Modra
Australia Development Lab, IBM