Re: PATCH: Adjust segment memory size for the SHT_NOBITS section

[Alan Modra <amodra at bigpond dot net dot au>]

On Fri, Mar 02, 2007 at 01:32:12PM +1030, Alan Modra wrote:
> Then of course you'd have to wonder why the code wasn't written that
> way in the first place.  Please do some digging to find out why.

I got curious and had a look myself.  It looks like my patch
http://sources.redhat.com/ml/binutils/2004-09/msg00225.html is at
fault here.  Previously, both SEC_LOAD and !SEC_LOAD sections
adjusted p_memsz based on their lmas.  Following that adjustment,
there was another based on vma.

I think we can just do the one based on lma, because if the lma to vma
relationship changes then map_sections_to_segments will choose a new
segment.  Of course, the user can specify segment mapping, lma, and
vma, but we can't do much except warn if the mapping is not
self-consistent.  Oh, and really old code had this note on the vma
based adjustment.

		  /* The section VMA must equal the file position
		     modulo the page size.  FIXME: I'm not sure if
		     this adjustment is really necessary.  We used to
		     not have the SEC_LOAD case just above, and then
		     this was necessary, but now I'm not sure.  */

This is what I have in mind.  I'll run some tests before applying,
eg. build glibc and gdb and run their tests as well as the binutils
testsuite.

	* elf.c (assign_file_positions_for_load_sections): Don't
	adjust p_memsz for !SEC_LOAD section vma modulo page size.
	Instead, use the same lma based adjustment for SEC_LOAD
	sections.

Index: bfd/elf.c
===================================================================
RCS file: /cvs/src/src/bfd/elf.c,v
retrieving revision 1.377
diff -u -p -r1.377 elf.c
--- bfd/elf.c	23 Feb 2007 11:47:47 -0000	1.377
+++ bfd/elf.c	2 Mar 2007 12:16:50 -0000
@@ -4495,11 +4495,13 @@ assign_file_positions_for_load_sections 
 	  if (p->p_type == PT_LOAD
 	      || p->p_type == PT_TLS)
 	    {
-	      bfd_signed_vma adjust;
+	      bfd_signed_vma adjust = sec->lma - (p->p_paddr + p->p_filesz);
 
-	      if ((flags & SEC_LOAD) != 0)
+	      if ((flags & SEC_LOAD) != 0
+		  || ((flags & SEC_ALLOC) != 0
+		      && ((flags & SEC_THREAD_LOCAL) == 0
+			  || p->p_type == PT_TLS)))
 		{
-		  adjust = sec->lma - (p->p_paddr + p->p_filesz);
 		  if (adjust < 0)
 		    {
 		      (*_bfd_error_handler)
@@ -4507,25 +4509,13 @@ assign_file_positions_for_load_sections 
 			 abfd, sec, (unsigned long) sec->lma);
 		      adjust = 0;
 		    }
-		  off += adjust;
-		  p->p_filesz += adjust;
-		  p->p_memsz += adjust;
-		}
-	      /* .tbss is special.  It doesn't contribute to p_memsz of
-		 normal segments.  */
-	      else if ((flags & SEC_ALLOC) != 0
-		       && ((flags & SEC_THREAD_LOCAL) == 0
-			   || p->p_type == PT_TLS))
-		{
-		  /* The section VMA must equal the file position
-		     modulo the page size.  */
-		  bfd_size_type page = align;
-		  if (page < maxpagesize)
-		    page = maxpagesize;
-		  adjust = vma_page_aligned_bias (sec->vma,
-						  p->p_vaddr + p->p_memsz,
-						  page);
 		  p->p_memsz += adjust;
+
+		  if ((flags & SEC_LOAD) != 0)
+		    {
+		      off += adjust;
+		      p->p_filesz += adjust;
+		    }
 		}
 	    }
 

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre