* mmo.c (mmo File layout documentation): Add note about low bits

	of address.
	(mmo_write_chunk): When handling data remainder, assert that
	previous remaining data is flushed.
	(mmo_write_loc_chunk): Only look for trailing and leading zeros
	when dealing with an aligned VMA and for aligned lengths.  Don't skip
	the last 32-bit-word of zeros.
	(mmo_write_loc_chunk): Emit an error if the VMA is not aligned.
	(mmo_scan) <case LOP_QUOTE>: Move re-alignment of vma before
	emitting data, not after updating it.
	<case LOP_LOC>: Call mmo_decide_section with aligned vma.

1 files changed, 43 insertions, 15 deletions

diff --git a/bfd/mmo.c b/bfd/mmo.c
index e8ce2882ef7..f52448cc901 100644
--- a/bfd/mmo.c
+++ b/bfd/mmo.c
@@ -88,7 +88,11 @@ SUBSECTION
 	directive, setting the location for the next data to the next
 	32-bit word (for @math{Z = 1}) or 64-bit word (for @math{Z = 2}),
 	plus @math{Y * 2^56}.  Normally @samp{Y} is 0 for the text segment
-	and 2 for the data segment.
+	and 2 for the data segment.  Beware that the low bits of non-
+	tetrabyte-aligned values are silently discarded when being
+	automatically incremented and when storing contents (in contrast
+	to e.g. its use as current location when followed by lop_fixo
+	et al before the next possibly-quoted tetrabyte contents).
 
 	@item lop_skip
 	0x9802YYZZ.  Increase the current location by @samp{YZ} bytes.
@@ -822,6 +826,9 @@ mmo_write_chunk (bfd *abfd, const bfd_byte *loc, unsigned int len)
 
   if (len)
     {
+      /* We must have flushed a previous remainder if we get one from
+	 this chunk too.  */
+      BFD_ASSERT (mmop->byte_no == 0);
       memcpy (mmop->buf, loc, len);
       mmop->byte_no = len;
     }
@@ -869,25 +876,27 @@ static bfd_boolean
 mmo_write_loc_chunk (bfd *abfd, bfd_vma vma, const bfd_byte *loc,
 		     unsigned int len, bfd_vma *last_vmap)
 {
-  /* Find an initial and trailing section of zero tetras; we don't need to
-     write out zeros.  FIXME: When we do this, we should emit section size
-     and address specifiers, else objcopy can't always perform an identity
-     translation.  Only do this if we *don't* have left-over data from a
-     previous write or the vma of this chunk is *not* the next address,
-     because then data isn't tetrabyte-aligned and we're concatenating to
-     that left-over data.  */
-
-  if (abfd->tdata.mmo_data->byte_no == 0 || vma != *last_vmap)
+  /* Find an initial and trailing section of zero (aligned) tetras; we don't
+     need to write out zeros.  FIXME: When we do this, we should emit
+     section size and address specifiers, else objcopy can't always perform
+     an identity translation.  Only do this if we *don't* have left-over
+     data from a previous write (and will not add any) or else the vma of
+     this chunk is *not* the next address, because then data isn't
+     tetrabyte-aligned and we're concatenating to that left-over data.  */
+
+  if ((vma & 3) == 0
+      && (abfd->tdata.mmo_data->byte_no == 0 || vma != *last_vmap))
     {
-      while (len >= 4 && bfd_get_32 (abfd, loc) == 0)
+      while (len > 4 && bfd_get_32 (abfd, loc) == 0)
 	{
 	  vma += 4;
 	  len -= 4;
 	  loc += 4;
 	}
 
-      while (len >= 4 && bfd_get_32 (abfd, loc + len - 4) == 0)
-	len -= 4;
+      if ((len & 3) == 0)
+	while (len > 4 && bfd_get_32 (abfd, loc + len - 4) == 0)
+	  len -= 4;
     }
 
   /* Only write out the location if it's different than the one the caller
@@ -897,6 +906,22 @@ mmo_write_loc_chunk (bfd *abfd, bfd_vma vma, const bfd_byte *loc,
       /* We might be in the middle of a sequence.  */
       mmo_flush_chunk (abfd);
 
+      /* This should not happen during normal usage, but can presumably
+	 happen with an erroneous linker-script, so handle gracefully.
+	 Avoid Knuth-specific terms in the message, such as "tetrabyte".
+	 Note that this function will get non-4-multiple lengths and
+	 unaligned vmas but those come in tuples (mostly pairs) and are
+	 continuous (i.e. the if-condition above false) and they are
+	 group-wise aligned.  */
+      if ((vma & 3) != 0)
+	{
+	  (*_bfd_error_handler)
+	    (_("%s: attempt to emit contents at non-multiple-of-4 address 0x%lx\n"),
+	     bfd_get_filename (abfd), (unsigned long) vma);
+	  bfd_set_error (bfd_error_bad_value);
+	  return FALSE;
+	}
+
       /* We always write the location as 64 bits; no use saving bytes
          here.  */
       mmo_write_tetra_raw (abfd, (LOP << 24) | (LOP_LOC << 16) | 2);
@@ -1583,9 +1608,9 @@ mmo_scan (bfd *abfd)
 	      if (bfd_bread (buf, 4, abfd) != 4)
 		goto error_return;
 
+	      vma &= ~3;
 	      mmo_xore_32 (sec, vma, bfd_get_32 (abfd, buf));
 	      vma += 4;
-	      vma &= ~3;
 	      lineno++;
 	      break;
 
@@ -1617,7 +1642,10 @@ mmo_scan (bfd *abfd)
 		  goto error_return;
 		}
 
-	      sec = mmo_decide_section (abfd, vma);
+	      /* When we decide which section the data goes into, we might
+		 create the section.  If that happens, make sure the VMA at
+		 creation time is tetra-aligned.  */
+	      sec = mmo_decide_section (abfd, vma & ~3);
 	      if (sec == NULL)
 		goto error_return;
 	      break;