deal with endian-ness in mach-o non-scattered relocs.

BFD:

	* mach-o.c (bfd_mach_o_swap_in_non_scattered_reloc): New.
	(bfd_mach_o_canonicalize_one_reloc):  Swap non-scattered reloc
	bit-fields when target and host differ in endian-ness.  When
	PAIRs are non-scattered	find the 'symbol' from the preceding
	reloc.  Add FIXME re. reloc symbols on section boundaries.
	(bfd_mach_o_swap_out_non_scattered_reloc): New.
	(bfd_mach_o_write_relocs): Use bfd_mach_o_encode_non_scattered_reloc.

include/mach-o:

	* external.h: Add comments about relocations fields.  Add macros
	for non-scattered relocations.  Move scattered relocation macros to here.
	* reloc.h: Remove macros related to external representation of reloc fields.

5 files changed, 174 insertions, 51 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 9447c63..6503f5c 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,13 @@
+2012-02-23  Iain Sandoe  <idsandoe@googlemail.com>
+
+	* mach-o.c (bfd_mach_o_swap_in_non_scattered_reloc): New.
+	(bfd_mach_o_canonicalize_one_reloc):  Swap non-scattered reloc
+	bit-fields when target and host differ in endian-ness.  When
+	PAIRs are non-scattered	find the 'symbol' from the preceding
+	reloc.  Add FIXME re. reloc symbols on section boundaries.
+	(bfd_mach_o_swap_out_non_scattered_reloc): New.
+	(bfd_mach_o_write_relocs): Use bfd_mach_o_encode_non_scattered_reloc.
+
 2012-02-17  Iain Sandoe  <idsandoe@googlemail.com>
 
 	* mach-o-i386.c (i386_howto_table): Add support for 16 bit
diff --git a/bfd/mach-o.c b/bfd/mach-o.c
index a7b9f80..1f9fc17 100644
--- a/bfd/mach-o.c
+++ b/bfd/mach-o.c
@@ -975,6 +975,35 @@ bfd_mach_o_get_reloc_upper_bound (bfd *abfd ATTRIBUTE_UNUSED,
   return (asect->reloc_count + 1) * sizeof (arelent *);
 }
 
+/* In addition to the need to byte-swap the symbol number, the bit positions
+   of the fields in the relocation information vary per target endian-ness.  */
+
+static void
+bfd_mach_o_swap_in_non_scattered_reloc (bfd *abfd, bfd_mach_o_reloc_info *rel,
+				       unsigned char *fields)
+{
+  unsigned char info = fields[3];
+
+  if (bfd_big_endian (abfd))
+    {
+      rel->r_value = (fields[0] << 16) | (fields[1] << 8) | fields[2];
+      rel->r_type = (info >> BFD_MACH_O_BE_TYPE_SHIFT) & BFD_MACH_O_TYPE_MASK;
+      rel->r_pcrel = (info & BFD_MACH_O_BE_PCREL) ? 1 : 0;
+      rel->r_length = (info >> BFD_MACH_O_BE_LENGTH_SHIFT) 
+		      & BFD_MACH_O_LENGTH_MASK;
+      rel->r_extern = (info & BFD_MACH_O_BE_EXTERN) ? 1 : 0;
+    }
+  else
+    {
+      rel->r_value = (fields[2] << 16) | (fields[1] << 8) | fields[0];
+      rel->r_type = (info >> BFD_MACH_O_LE_TYPE_SHIFT) & BFD_MACH_O_TYPE_MASK;
+      rel->r_pcrel = (info & BFD_MACH_O_LE_PCREL) ? 1 : 0;
+      rel->r_length = (info >> BFD_MACH_O_LE_LENGTH_SHIFT) 
+		      & BFD_MACH_O_LENGTH_MASK;
+      rel->r_extern = (info & BFD_MACH_O_LE_EXTERN) ? 1 : 0;
+    }
+}
+
 static int
 bfd_mach_o_canonicalize_one_reloc (bfd *abfd,
                                    struct mach_o_reloc_info_external *raw,
@@ -984,20 +1013,28 @@ bfd_mach_o_canonicalize_one_reloc (bfd *abfd,
   bfd_mach_o_backend_data *bed = bfd_mach_o_get_backend_data (abfd);
   bfd_mach_o_reloc_info reloc;
   bfd_vma addr;
-  bfd_vma symnum;
   asymbol **sym;
 
   addr = bfd_get_32 (abfd, raw->r_address);
-  symnum = bfd_get_32 (abfd, raw->r_symbolnum);
+  res->sym_ptr_ptr = NULL;
+  res->addend = 0;
   
   if (addr & BFD_MACH_O_SR_SCATTERED)
     {
       unsigned int j;
+      bfd_vma symnum = bfd_get_32 (abfd, raw->r_symbolnum);
 
-      /* Scattered relocation.
-         Extract section and offset from r_value.  */
-      res->sym_ptr_ptr = NULL;
-      res->addend = 0;
+      /* Scattered relocation, can't be extern. */
+      reloc.r_scattered = 1;
+      reloc.r_extern = 0;
+
+      /*   Extract section and offset from r_value (symnum).  */
+      reloc.r_value = symnum;
+      /* FIXME: This breaks when a symbol in a reloc exactly follows the
+	 end of the data for the section (e.g. in a calculation of section
+	 data length).  At present, the symbol will end up associated with
+	 the following section or, if it falls within alignment padding, as
+	 null - which will assert later.  */
       for (j = 0; j < mdata->nsects; j++)
         {
           bfd_mach_o_section *sect = mdata->sections[j];
@@ -1008,42 +1045,62 @@ bfd_mach_o_canonicalize_one_reloc (bfd *abfd,
               break;
             }
         }
-      res->address = BFD_MACH_O_GET_SR_ADDRESS (addr);
+
+      /* Extract the info and address fields from r_address.  */
       reloc.r_type = BFD_MACH_O_GET_SR_TYPE (addr);
       reloc.r_length = BFD_MACH_O_GET_SR_LENGTH (addr);
       reloc.r_pcrel = addr & BFD_MACH_O_SR_PCREL;
-      reloc.r_scattered = 1;
+      reloc.r_address = BFD_MACH_O_GET_SR_TYPE (addr);
+      res->address = BFD_MACH_O_GET_SR_ADDRESS (addr);
     }
   else
     {
-      unsigned int num = BFD_MACH_O_GET_R_SYMBOLNUM (symnum);
-      res->addend = 0;
-      res->address = addr;
-      if (symnum & BFD_MACH_O_R_EXTERN)
-        {
+      unsigned int num;
+      
+      /* Non-scattered relocation.  */
+      reloc.r_scattered = 0;
+      
+      /* The value and info fields have to be extracted dependent on target
+         endian-ness.  */
+      bfd_mach_o_swap_in_non_scattered_reloc (abfd, &reloc, raw->r_symbolnum);
+      num = reloc.r_value;
+
+      if (reloc.r_extern)
           sym = syms + num;
-          reloc.r_extern = 1;
-        }
-      else
+      else if (reloc.r_scattered
+	       || (reloc.r_type != BFD_MACH_O_GENERIC_RELOC_PAIR))
         {
           BFD_ASSERT (num != 0);
           BFD_ASSERT (num <= mdata->nsects);
           sym = mdata->sections[num - 1]->bfdsection->symbol_ptr_ptr;
           /* For a symbol defined in section S, the addend (stored in the
              binary) contains the address of the section.  To comply with
-             bfd conventio, substract the section address.
+             bfd convention, subtract the section address.
              Use the address from the header, so that the user can modify
              the vma of the section.  */
           res->addend = -mdata->sections[num - 1]->addr;
-          reloc.r_extern = 0;
+        }
+      else /* ... The 'symnum' in a non-scattered PAIR will be 0x00ffffff.  */
+        {
+          /* Pairs for PPC LO/HI/HA are not scattered, but contain the offset
+             in the lower 16bits of the address value.  So we have to find the
+             'symbol' from the preceding reloc.  We do this even thoough the
+             section symbol is probably not needed here, because NULL symbol
+             values cause an assert in generic BFD code.  */
+          sym = (res - 1)->sym_ptr_ptr;
         }
       res->sym_ptr_ptr = sym;
-      reloc.r_type = BFD_MACH_O_GET_R_TYPE (symnum);
-      reloc.r_length = BFD_MACH_O_GET_R_LENGTH (symnum);
-      reloc.r_pcrel = (symnum & BFD_MACH_O_R_PCREL) ? 1 : 0;
-      reloc.r_scattered = 0;
+      
+      /* The 'address' is just r_address.
+         ??? maybe this should be masked with  0xffffff for safety.  */
+      res->address = addr;
+      reloc.r_address = addr;
     }
   
+  /* We have set up a reloc with all the information present, so the swapper can
+     modify address, value and addend fields, if necessary, to convey information
+     in the generic BFD reloc that is mach-o specific.  */
+
   if (!(*bed->_bfd_mach_o_swap_reloc_in)(res, &reloc))
     return -1;
   return 0;
@@ -1182,6 +1239,41 @@ bfd_mach_o_canonicalize_dynamic_reloc (bfd *abfd, arelent **rels,
   return i;
 }
 
+/* In addition to the need to byte-swap the symbol number, the bit positions
+   of the fields in the relocation information vary per target endian-ness.  */
+
+static void
+bfd_mach_o_swap_out_non_scattered_reloc (bfd *abfd, unsigned char *fields,
+				       bfd_mach_o_reloc_info *rel)
+{
+  unsigned char info = 0;
+
+  BFD_ASSERT (rel->r_type <= 15);
+  BFD_ASSERT (rel->r_length <= 3);
+
+  if (bfd_big_endian (abfd))
+    {
+      fields[0] = (rel->r_value >> 16) & 0xff;
+      fields[1] = (rel->r_value >> 8) & 0xff;
+      fields[2] = rel->r_value & 0xff;
+      info |= rel->r_type << BFD_MACH_O_BE_TYPE_SHIFT;
+      info |= rel->r_pcrel ? BFD_MACH_O_BE_PCREL : 0;
+      info |= rel->r_length << BFD_MACH_O_BE_LENGTH_SHIFT;
+      info |= rel->r_extern ? BFD_MACH_O_BE_EXTERN : 0;
+    }
+  else
+    {
+      fields[2] = (rel->r_value >> 16) & 0xff;
+      fields[1] = (rel->r_value >> 8) & 0xff;
+      fields[0] = rel->r_value & 0xff;
+      info |= rel->r_type << BFD_MACH_O_LE_TYPE_SHIFT;
+      info |= rel->r_pcrel ? BFD_MACH_O_LE_PCREL : 0;
+      info |= rel->r_length << BFD_MACH_O_LE_LENGTH_SHIFT;
+      info |= rel->r_extern ? BFD_MACH_O_LE_EXTERN : 0;
+    }
+  fields[3] = info;
+}
+
 static bfd_boolean
 bfd_mach_o_write_relocs (bfd *abfd, bfd_mach_o_section *section)
 {
@@ -1228,15 +1320,9 @@ bfd_mach_o_write_relocs (bfd *abfd, bfd_mach_o_section *section)
         }
       else
         {
-          unsigned long v;
-
           bfd_put_32 (abfd, pinfo->r_address, raw.r_address);
-          v = BFD_MACH_O_SET_R_SYMBOLNUM (pinfo->r_value)
-            | (pinfo->r_pcrel ? BFD_MACH_O_R_PCREL : 0)
-            | BFD_MACH_O_SET_R_LENGTH (pinfo->r_length)
-            | (pinfo->r_extern ? BFD_MACH_O_R_EXTERN : 0)
-            | BFD_MACH_O_SET_R_TYPE (pinfo->r_type);
-          bfd_put_32 (abfd, v, raw.r_symbolnum);
+          bfd_mach_o_swap_out_non_scattered_reloc (abfd, raw.r_symbolnum,
+						   pinfo);
         }
 
       if (bfd_bwrite (&raw, BFD_MACH_O_RELENT_SIZE, abfd)
diff --git a/include/mach-o/ChangeLog b/include/mach-o/ChangeLog
index ab3cc68..19eacd0 100644
--- a/include/mach-o/ChangeLog
+++ b/include/mach-o/ChangeLog
@@ -1,3 +1,11 @@
+2012-02-23  Iain Sandoe  <idsandoe@googlemail.com>
+
+	* external.h: Add comments about relocations fields.  Add macros
+	for non-scattered relocations.  Move scattered relocation macros to
+	here.
+	* reloc.h: Remove macros related to external representation of reloc
+	fields.
+
 2012-01-12  Iain Sandoe  <idsandoe@googlemail.com>
 
 	* loader.h (BFD_MACH_O_INDIRECT_SYM_LOCAL): New.
diff --git a/include/mach-o/external.h b/include/mach-o/external.h
index ad419ef..41a2932 100644
--- a/include/mach-o/external.h
+++ b/include/mach-o/external.h
@@ -116,6 +116,45 @@ struct mach_o_reloc_info_external
 };
 #define BFD_MACH_O_RELENT_SIZE 8
 
+/* Relocations are based on 'address' being a section offset and an assumption
+   that sections are never more than 2^24-1 bytes in size.  Relocation data
+   also carry information on type/size/PC-relative/extern and whether scattered
+   or not [stored in the MSB of the r_address].  */
+
+#define BFD_MACH_O_SR_SCATTERED		0x80000000
+
+/* For a non-scattered reloc, the relocation info is found in r_symbolnum.
+   Bytes 1 to 3 contain the symbol number (0xffffff, in a non-scattered PAIR).  
+   Byte 4 contains the relocation info - but with differing bit-positions
+   dependent on target endian-ness - as below.  */
+
+#define BFD_MACH_O_LE_PCREL		0x01
+#define BFD_MACH_O_LE_LENGTH_SHIFT	1
+#define BFD_MACH_O_LE_EXTERN		0x08
+#define BFD_MACH_O_LE_TYPE_SHIFT	4
+
+#define BFD_MACH_O_BE_PCREL		0x80
+#define BFD_MACH_O_BE_LENGTH_SHIFT	5
+#define BFD_MACH_O_BE_EXTERN		0x10
+#define BFD_MACH_O_BE_TYPE_SHIFT	0
+
+/* The field sizes are the same for both BE and LE.  */
+#define BFD_MACH_O_LENGTH_MASK		0x03
+#define BFD_MACH_O_TYPE_MASK		0x0f
+
+/* For a scattered reloc entry the info is contained in r_address.  There
+   is no need to discriminate on target endian-ness, since the design was
+   arranged to produce the same layout on both.  Scattered relocations are
+   only used for local items, therefore there is no 'extern' field.  */
+
+#define BFD_MACH_O_SR_PCREL		0x40000000
+#define BFD_MACH_O_GET_SR_LENGTH(s)	(((s) >> 28) & 0x3)
+#define BFD_MACH_O_GET_SR_TYPE(s)	(((s) >> 24) & 0x0f)
+#define BFD_MACH_O_GET_SR_ADDRESS(s)	((s) & 0x00ffffff)
+#define BFD_MACH_O_SET_SR_LENGTH(l)	(((l) & 0x3) << 28)
+#define BFD_MACH_O_SET_SR_TYPE(t)	(((t) & 0xf) << 24)
+#define BFD_MACH_O_SET_SR_ADDRESS(s)	((s) & 0x00ffffff)
+
 struct mach_o_symtab_command_external
 {
   unsigned char symoff[4];	/* File offset of the symbol table.  */
diff --git a/include/mach-o/reloc.h b/include/mach-o/reloc.h
index 93ebb8b..bab31ef 100644
--- a/include/mach-o/reloc.h
+++ b/include/mach-o/reloc.h
@@ -1,5 +1,5 @@
 /* Mach-O support for BFD.
-   Copyright 2011
+   Copyright 2011, 2012
    Free Software Foundation, Inc.
 
    This file is part of BFD, the Binary File Descriptor library.
@@ -22,26 +22,6 @@
 #ifndef _MACH_O_RELOC_H
 #define _MACH_O_RELOC_H
 
-/* Fields for a normal (non-scattered) entry.  */
-#define BFD_MACH_O_R_PCREL		0x01000000
-#define BFD_MACH_O_GET_R_LENGTH(s)	(((s) >> 25) & 0x3)
-#define BFD_MACH_O_R_EXTERN		0x08000000
-#define BFD_MACH_O_GET_R_TYPE(s)	(((s) >> 28) & 0x0f)
-#define BFD_MACH_O_GET_R_SYMBOLNUM(s)	((s) & 0x00ffffff)
-#define BFD_MACH_O_SET_R_LENGTH(l)	(((l) & 0x3) << 25)
-#define BFD_MACH_O_SET_R_TYPE(t)	(((t) & 0xf) << 28)
-#define BFD_MACH_O_SET_R_SYMBOLNUM(s)	((s) & 0x00ffffff)
-
-/* Fields for a scattered entry.  */
-#define BFD_MACH_O_SR_SCATTERED		0x80000000
-#define BFD_MACH_O_SR_PCREL		0x40000000
-#define BFD_MACH_O_GET_SR_LENGTH(s)	(((s) >> 28) & 0x3)
-#define BFD_MACH_O_GET_SR_TYPE(s)	(((s) >> 24) & 0x0f)
-#define BFD_MACH_O_GET_SR_ADDRESS(s)	((s) & 0x00ffffff)
-#define BFD_MACH_O_SET_SR_LENGTH(l)	(((l) & 0x3) << 28)
-#define BFD_MACH_O_SET_SR_TYPE(t)	(((t) & 0xf) << 24)
-#define BFD_MACH_O_SET_SR_ADDRESS(s)	((s) & 0x00ffffff)
-
 /* Generic relocation types (used by i386).  */
 #define BFD_MACH_O_GENERIC_RELOC_VANILLA 	0
 #define BFD_MACH_O_GENERIC_RELOC_PAIR	 	1