Re: VMA section overlap warnings for overlays

[Alan Modra <amodra at gmail dot com>]

On Mon, Jul 19, 2010 at 02:42:58PM +0200, Andreas Schwab wrote:
> ELF_SECTION_SIZE is also weird.  It returns 0 for a .tbss section
> outside a TLS segment, but that makes it impossible to distinguish it
> from a genuine empty section.  There are two uses of ELF_SECTION_SIZE
> together with ELF_SECTION_IN_SEGMENT, which are in readelf.c end
> elf32-spu.c.

I think the one in elf32-spu.c can be removed.

>  Thus readelf -l never considers an empty section be part
> of any segment, but removing the ELF_SECTION_SIZE check causes the .tbss
> section to be mishandled.  I think ELF_SECTION_IN_SEGMENT_1 should be
> modified to handle the special case of .tbss directly.

It will also need changing to properly handle zero size sections at
the end of a segment.  Currently, zero size sections may wrongly match
at the end of a segment, or match multiple segments.  For instance, if
you just keep the special handling for .tbss in readelf but allow zero
size sections, then a number of powerpc tests fail as follows:

regexp_diff match failure
regexp "^ +03 +\.tdata \.dynamic \.got \.plt $"
line   "   03     .tdata .dynamic .branch_lt .got .plt "
regexp_diff match failure
regexp "^ +04 +\.dynamic $"
line   "   04     .dynamic .branch_lt "
FAIL: TLSTOC dynamic exec

The first difference is expected;  We now include the zero size
.branch_lt in a PT_LOAD header.  The second difference is
problematic.  .branch_lt doesn't really belong in PT_DYNAMIC.

-- 
Alan Modra
Australia Development Lab, IBM