Re: VMA section overlap warnings for overlays

[Alan Modra <amodra@gmail.com>]

On Thu, Feb 24, 2011 at 03:49:25PM -0800, H.J. Lu wrote:
> On Tue, Jul 20, 2010 at 7:10 AM, Alan Modra <amodra@gmail.com> wrote:
> > This removes all the special treatment for zero size sections when
> > using ELF_SECTION_IN_SEGMENT in elf.c, and makes readelf display
[snip]
> This may have caused:
> 
> http://sourceware.org/bugzilla/show_bug.cgi?id=12516

Yes, looks like it.

	PR 12519
	* internal.h (ELF_SECTION_IN_SEGMENT_1): Don't match zero size
	sections at start or end of PT_DYNAMIC.

Index: include/elf/internal.h
===================================================================
RCS file: /cvs/src/src/include/elf/internal.h,v
retrieving revision 1.26
diff -u -p -r1.26 internal.h
--- include/elf/internal.h	20 Jul 2010 14:08:30 -0000	1.26
+++ include/elf/internal.h	25 Feb 2011 04:28:30 -0000
@@ -302,7 +302,9 @@ struct elf_segment_map
 /* Decide if the section SEC_HDR is in SEGMENT.  If CHECK_VMA, then
    VMAs are checked for alloc sections.  If STRICT, then a zero size
    section won't match at the end of a segment, unless the segment
-   is also zero size.  */
+   is also zero size.  Regardless of STRICT and CHECK_VMA, zero size
+   sections won't match at the start or end of PT_DYNAMIC, unless
+   PT_DYNAMIC is itself zero sized.  */
 #define ELF_SECTION_IN_SEGMENT_1(sec_hdr, segment, check_vma, strict)	\
   ((/* Only PT_LOAD, PT_GNU_RELRO and PT_TLS segments can contain	\
        SHF_TLS sections.  */						\
@@ -334,7 +336,19 @@ struct elf_segment_map
 		   <= (segment)->p_memsz - 1))				\
 	   && (((sec_hdr)->sh_addr - (segment)->p_vaddr			\
 		+ ELF_SECTION_SIZE(sec_hdr, segment))			\
-	       <= (segment)->p_memsz))))
+	       <= (segment)->p_memsz)))					\
+   /* No zero size sections at start or end of PT_DYNAMIC.  */		\
+   && ((segment)->p_type != PT_DYNAMIC					\
+       || (sec_hdr)->sh_size != 0					\
+       || (segment)->p_memsz == 0					\
+       || (((sec_hdr)->sh_type == SHT_NOBITS				\
+	    || ((bfd_vma) (sec_hdr)->sh_offset > (segment)->p_offset	\
+	        && ((sec_hdr)->sh_offset - (segment)->p_offset		\
+		    < (segment)->p_filesz)))				\
+	   && (((sec_hdr)->sh_flags & SHF_ALLOC) == 0			\
+	       || ((sec_hdr)->sh_addr > (segment)->p_vaddr		\
+		   && ((sec_hdr)->sh_addr - (segment)->p_vaddr		\
+		       < (segment)->p_memsz))))))
 
 #define ELF_SECTION_IN_SEGMENT(sec_hdr, segment)			\
   (ELF_SECTION_IN_SEGMENT_1 (sec_hdr, segment, 1, 0))

-- 
Alan Modra
Australia Development Lab, IBM