Align eh_frame FDEs according to their encoding

bfd/
	* elf-bfd.h (struct eh_cie_fde): Add u.cie.per_encoding_aligned8.
	* elf-eh-frame.c (size_of_output_cie_fde): Don't align here.
	(next_cie_fde_offset): New function.
	(_bfd_elf_parse_eh_frame): Set u.cie.per_encoding_aligned8.
	(_bfd_elf_discard_section_eh_frame): Align zero terminator to
	four bytes.  Align CIEs to four or eight bytes depending on
	per_encoding_aligned8.  Align FDEs according to their encoding.
	Pad last FDE to output section alignment.
	(_bfd_elf_write_section_eh_frame): Adjust to suit.  Remove
	assertion.
	* elf64-ppc.c (glink_eh_frame_cie): Delete padding.
	(ppc64_elf_size_stubs): Pad glink eh_frame as per elf-eh-frame.c.
	(ppc64_elf_finish_dynamic_sections): Adjust to suit.
ld/
	* testsuite/ld-elf/eh3.d: Adjust for eh_frame alignment change.
	* testsuite/ld-elf/eh6.d: Likewise.
	* testsuite/ld-alpha/tlsbin.dd: Likewise.
	* testsuite/ld-alpha/tlsbin.td: Likewise.
	* testsuite/ld-alpha/tlsbinr.dd: Likewise.
	* testsuite/ld-alpha/tlspic.dd: Likewise.
	* testsuite/ld-alpha/tlspic.rd: Likewise.
	* testsuite/ld-alpha/tlspic.sd: Likewise.
	* testsuite/ld-alpha/tlspic.td: Likewise.
	* testsuite/ld-mips-elf/eh-frame1-n64.d: Likewise.
	* testsuite/ld-mips-elf/eh-frame2-n64.d: Likewise.
	* testsuite/ld-mips-elf/eh-frame3.d: Likewise.
	* testsuite/ld-x86-64/pr20830a.d: Likewise.
	* testsuite/ld-x86-64/pr21038a.d: Likewise.
	* testsuite/ld-x86-64/pr21038b.d: Likewise.
	* testsuite/ld-x86-64/pr21038c.d: Likewise.

1 files changed, 59 insertions, 24 deletions

diff --git a/bfd/elf-eh-frame.c b/bfd/elf-eh-frame.c
index 1b03b9b..6967f37 100644
--- a/bfd/elf-eh-frame.c
+++ b/bfd/elf-eh-frame.c
@@ -309,11 +309,10 @@ extra_augmentation_data_bytes (struct eh_cie_fde *entry)
   return size;
 }
 
-/* Return the size that ENTRY will have in the output.  ALIGNMENT is the
-   required alignment of ENTRY in bytes.  */
+/* Return the size that ENTRY will have in the output.  */
 
 static unsigned int
-size_of_output_cie_fde (struct eh_cie_fde *entry, unsigned int alignment)
+size_of_output_cie_fde (struct eh_cie_fde *entry)
 {
   if (entry->removed)
     return 0;
@@ -321,8 +320,22 @@ size_of_output_cie_fde (struct eh_cie_fde *entry, unsigned int alignment)
     return 4;
   return (entry->size
 	  + extra_augmentation_string_bytes (entry)
-	  + extra_augmentation_data_bytes (entry)
-	  + alignment - 1) & -alignment;
+	  + extra_augmentation_data_bytes (entry));
+}
+
+/* Return the offset of the FDE or CIE after ENT.  */
+
+static unsigned int
+next_cie_fde_offset (struct eh_cie_fde *ent,
+		     struct eh_cie_fde *last,
+		     asection *sec)
+{
+  while (++ent < last)
+    {
+      if (!ent->removed)
+	return ent->new_offset;
+    }
+  return sec->size;
 }
 
 /* Assume that the bytes between *ITER and END are CFA instructions.
@@ -811,6 +824,8 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
 			{
 			  length = -(buf - ehbuf) & (per_width - 1);
 			  REQUIRE (skip_bytes (&buf, end, length));
+			  if (per_width == 8)
+			    this_inf->u.cie.per_encoding_aligned8 = 1;
 			}
 		      this_inf->u.cie.personality_offset = buf - start;
 		      ENSURE_NO_RELOCS (buf);
@@ -1326,7 +1341,7 @@ _bfd_elf_discard_section_eh_frame
   struct eh_cie_fde *ent;
   struct eh_frame_sec_info *sec_info;
   struct eh_frame_hdr_info *hdr_info;
-  unsigned int ptr_size, offset;
+  unsigned int ptr_size, offset, eh_alignment;
 
   if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
     return FALSE;
@@ -1406,14 +1421,46 @@ _bfd_elf_discard_section_eh_frame
       sec_info->cies = NULL;
     }
 
+  /* It may be that some .eh_frame input section has greater alignment
+     than other .eh_frame sections.  In that case we run the risk of
+     padding with zeros before that section, which would be seen as a
+     zero terminator.  Alignment padding must be added *inside* the
+     last FDE instead.  For other FDEs we align according to their
+     encoding, in order to align FDE address range entries naturally.  */
   offset = 0;
   for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
     if (!ent->removed)
       {
+	eh_alignment = 4;
+	if (ent->size == 4)
+	  ;
+	else if (ent->cie)
+	  {
+	    if (ent->u.cie.per_encoding_aligned8)
+	      eh_alignment = 8;
+	  }
+	else
+	  {
+	    eh_alignment = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
+	    if (eh_alignment < 4)
+	      eh_alignment = 4;
+	  }
+	offset = (offset + eh_alignment - 1) & -eh_alignment;
 	ent->new_offset = offset;
-	offset += size_of_output_cie_fde (ent, ptr_size);
+	offset += size_of_output_cie_fde (ent);
       }
 
+  /* Pad the last FDE out to the output section alignment if there are
+     following sections, in order to ensure no padding between this
+     section and the next.  (Relies on the output section alignment
+     being the maximum of all input sections alignments, which is the
+     case unless someone is overriding alignment via scripts.)  */
+  eh_alignment = 4;
+  if (sec->map_head.s != NULL
+      && (sec->map_head.s->size != 4
+	  || sec->map_head.s->map_head.s != NULL))
+    eh_alignment = 1 << sec->output_section->alignment_power;
+  offset = (offset + eh_alignment - 1) & -eh_alignment;
   sec->rawsize = sec->size;
   sec->size = offset;
   return offset != sec->rawsize;
@@ -1732,8 +1779,7 @@ _bfd_elf_write_section_eh_frame (bfd *abfd,
   struct elf_link_hash_table *htab;
   struct eh_frame_hdr_info *hdr_info;
   unsigned int ptr_size;
-  struct eh_cie_fde *ent;
-  bfd_size_type sec_size;
+  struct eh_cie_fde *ent, *last_ent;
 
   if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
     /* FIXME: octets_per_byte.  */
@@ -1771,7 +1817,8 @@ _bfd_elf_write_section_eh_frame (bfd *abfd,
     if (!ent->removed && ent->new_offset < ent->offset)
       memmove (contents + ent->new_offset, contents + ent->offset, ent->size);
 
-  for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
+  last_ent = sec_info->entry + sec_info->count;
+  for (ent = sec_info->entry; ent < last_ent; ++ent)
     {
       unsigned char *buf, *end;
       unsigned int new_size;
@@ -1782,13 +1829,13 @@ _bfd_elf_write_section_eh_frame (bfd *abfd,
       if (ent->size == 4)
 	{
 	  /* Any terminating FDE must be at the end of the section.  */
-	  BFD_ASSERT (ent == sec_info->entry + sec_info->count - 1);
+	  BFD_ASSERT (ent == last_ent - 1);
 	  continue;
 	}
 
       buf = contents + ent->new_offset;
       end = buf + ent->size;
-      new_size = size_of_output_cie_fde (ent, ptr_size);
+      new_size = next_cie_fde_offset (ent, last_ent, sec) - ent->new_offset;
 
       /* Update the size.  It may be shrinked.  */
       bfd_put_32 (abfd, new_size - 4, buf);
@@ -2059,18 +2106,6 @@ _bfd_elf_write_section_eh_frame (bfd *abfd,
 	}
     }
 
-  /* We don't align the section to its section alignment since the
-     runtime library only expects all CIE/FDE records aligned at
-     the pointer size. _bfd_elf_discard_section_eh_frame should
-     have padded CIE/FDE records to multiple of pointer size with
-     size_of_output_cie_fde.  */
-  sec_size = sec->size;
-  if (sec_info->count != 0
-      && sec_info->entry[sec_info->count - 1].size == 4)
-    sec_size -= 4;
-  if ((sec_size % ptr_size) != 0)
-    abort ();
-
   /* FIXME: octets_per_byte.  */
   return bfd_set_section_contents (abfd, sec->output_section,
 				   contents, (file_ptr) sec->output_offset,