xtensa: fix PR ld/25861

Introduce new relaxations XTENSA_PDIFF{8,16,32} for positive differences
(subtracted symbol precedes diminished symbol) and XTENSA_NDIFF{8,16,32}
for negative differences (subtracted symbol follows diminished symbol).
Don't generate XTENSA_DIFF relocations in the assembler, generate
XTENSA_PDIFF or XTENSA_NDIFF based on relative symbol position.

Handle XTENSA_DIFF in BFD for compatibility with old object files.
Handle XTENSA_PDIFF and XTENSA_NDIFF in BFD, treating difference value
as unsigned.

2020-04-22  Max Filippov  <jcmvbkbc@gmail.com>
bfd/
	* bfd-in2.h: Regenerated.
	* elf32-xtensa.c (elf_howto_table): New entries for
	R_XTENSA_PDIFF{8,16,32} and R_XTENSA_NDIFF{8,16,32}.
	(elf_xtensa_reloc_type_lookup, elf_xtensa_do_reloc)
	(relax_section): Add cases for R_XTENSA_PDIFF{8,16,32} and
	R_XTENSA_NDIFF{8,16,32}.
	* libbfd.h (bfd_reloc_code_real_names): Add names for
	BFD_RELOC_XTENSA_PDIFF{8,16,32} and
	BFD_RELOC_XTENSA_NDIFF{8,16,32}.
	* reloc.c: Add documentation for BFD_RELOC_XTENSA_PDIFF{8,16,32}
	and BFD_RELOC_XTENSA_NDIFF{8,16,32}.

binutils/
	* readelf.c (is_none_reloc): Recognize
	BFD_RELOC_XTENSA_PDIFF{8,16,32} and
	BFD_RELOC_XTENSA_NDIFF{8,16,32}.

gas/
	* config/tc-xtensa.c (md_apply_fix): Replace
	BFD_RELOC_XTENSA_DIFF{8,16,32} generation with
	BFD_RELOC_XTENSA_PDIFF{8,16,32} and
	BFD_RELOC_XTENSA_NDIFF{8,16,32} generation.
	* testsuite/gas/xtensa/loc.d: Replace BFD_RELOC_XTENSA_DIFF16
	with BFD_RELOC_XTENSA_PDIFF16 in the expected output.

include/
	* elf/xtensa.h (elf_xtensa_reloc_type): New entries for
	R_XTENSA_PDIFF{8,16,32} and R_XTENSA_NDIFF{8,16,32}.

ld/
	* testsuite/ld-xtensa/relax-loc.d: New test definition.
	* testsuite/ld-xtensa/relax-loc.s: New test source.
	* testsuite/ld-xtensa/xtensa.exp (relax-loc): New test.

5 files changed, 152 insertions, 2 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 0712414..adba80c 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,18 @@
+2020-04-22  Max Filippov  <jcmvbkbc@gmail.com>
+
+	PR ld/25861
+	* bfd-in2.h: Regenerated.
+	* elf32-xtensa.c (elf_howto_table): New entries for
+	R_XTENSA_PDIFF{8,16,32} and R_XTENSA_NDIFF{8,16,32}.
+	(elf_xtensa_reloc_type_lookup, elf_xtensa_do_reloc)
+	(relax_section): Add cases for R_XTENSA_PDIFF{8,16,32} and
+	R_XTENSA_NDIFF{8,16,32}.
+	* libbfd.h (bfd_reloc_code_real_names): Add names for
+	BFD_RELOC_XTENSA_PDIFF{8,16,32} and
+	BFD_RELOC_XTENSA_NDIFF{8,16,32}.
+	* reloc.c: Add documentation for BFD_RELOC_XTENSA_PDIFF{8,16,32}
+	and BFD_RELOC_XTENSA_NDIFF{8,16,32}.
+
 2020-04-21  Tamar Christina  <tamar.christina@arm.com>
 
 	PR binutils/24753
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 8693f86..ec23fd4 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -5224,7 +5224,9 @@ to one of its own internal functions or data structures.  */
 PLT entries.  Otherwise, this is just a generic 32-bit relocation.  */
   BFD_RELOC_XTENSA_PLT,
 
-/* Xtensa relocations to mark the difference of two local symbols.
+/* Xtensa relocations for backward compatibility.  These have been replaced
+by BFD_RELOC_XTENSA_PDIFF and BFD_RELOC_XTENSA_NDIFF.
+Xtensa relocations to mark the difference of two local symbols.
 These are only needed to support linker relaxation and can be ignored
 when not relaxing.  The field is set to the value of the difference
 assuming no relaxation.  The relocation encodes the position of the
@@ -5298,6 +5300,22 @@ BFD_RELOC_XTENSA_ASM_EXPAND.  */
   BFD_RELOC_XTENSA_TLS_ARG,
   BFD_RELOC_XTENSA_TLS_CALL,
 
+/* Xtensa relocations to mark the difference of two local symbols.
+These are only needed to support linker relaxation and can be ignored
+when not relaxing.  The field is set to the value of the difference
+assuming no relaxation.  The relocation encodes the position of the
+subtracted symbol so the linker can determine whether to adjust the field
+value.  PDIFF relocations are used for positive differences, NDIFF
+relocations are used for negative differences.  The difference value
+is treated as unsigned with these relocation types, giving full
+8/16 value ranges.  */
+  BFD_RELOC_XTENSA_PDIFF8,
+  BFD_RELOC_XTENSA_PDIFF16,
+  BFD_RELOC_XTENSA_PDIFF32,
+  BFD_RELOC_XTENSA_NDIFF8,
+  BFD_RELOC_XTENSA_NDIFF16,
+  BFD_RELOC_XTENSA_NDIFF32,
+
 /* 8 bit signed offset in (ix+d) or (iy+d).  */
   BFD_RELOC_Z80_DISP8,
 
diff --git a/bfd/elf32-xtensa.c b/bfd/elf32-xtensa.c
index 473a9d7..fded42d 100644
--- a/bfd/elf32-xtensa.c
+++ b/bfd/elf32-xtensa.c
@@ -325,6 +325,20 @@ static reloc_howto_type elf_howto_table[] =
   HOWTO (R_XTENSA_TLS_CALL, 0, 0, 0, FALSE, 0, complain_overflow_dont,
 	 bfd_elf_xtensa_reloc, "R_XTENSA_TLS_CALL",
 	 FALSE, 0, 0, FALSE),
+
+  HOWTO (R_XTENSA_PDIFF8, 0, 0, 8, FALSE, 0, complain_overflow_bitfield,
+	 bfd_elf_xtensa_reloc, "R_XTENSA_PDIFF8", FALSE, 0, 0xff, FALSE),
+  HOWTO (R_XTENSA_PDIFF16, 0, 1, 16, FALSE, 0, complain_overflow_bitfield,
+	 bfd_elf_xtensa_reloc, "R_XTENSA_PDIFF16", FALSE, 0, 0xffff, FALSE),
+  HOWTO (R_XTENSA_PDIFF32, 0, 2, 32, FALSE, 0, complain_overflow_bitfield,
+	 bfd_elf_xtensa_reloc, "R_XTENSA_PDIFF32", FALSE, 0, 0xffffffff, FALSE),
+
+  HOWTO (R_XTENSA_NDIFF8, 0, 0, 8, FALSE, 0, complain_overflow_bitfield,
+	 bfd_elf_xtensa_reloc, "R_XTENSA_NDIFF8", FALSE, 0, 0xff, FALSE),
+  HOWTO (R_XTENSA_NDIFF16, 0, 1, 16, FALSE, 0, complain_overflow_bitfield,
+	 bfd_elf_xtensa_reloc, "R_XTENSA_NDIFF16", FALSE, 0, 0xffff, FALSE),
+  HOWTO (R_XTENSA_NDIFF32, 0, 2, 32, FALSE, 0, complain_overflow_bitfield,
+	 bfd_elf_xtensa_reloc, "R_XTENSA_NDIFF32", FALSE, 0, 0xffffffff, FALSE),
 };
 
 #if DEBUG_GEN_RELOC
@@ -364,6 +378,30 @@ elf_xtensa_reloc_type_lookup (bfd *abfd ATTRIBUTE_UNUSED,
       TRACE ("BFD_RELOC_XTENSA_DIFF32");
       return &elf_howto_table[(unsigned) R_XTENSA_DIFF32 ];
 
+    case BFD_RELOC_XTENSA_PDIFF8:
+      TRACE ("BFD_RELOC_XTENSA_PDIFF8");
+      return &elf_howto_table[(unsigned) R_XTENSA_PDIFF8 ];
+
+    case BFD_RELOC_XTENSA_PDIFF16:
+      TRACE ("BFD_RELOC_XTENSA_PDIFF16");
+      return &elf_howto_table[(unsigned) R_XTENSA_PDIFF16 ];
+
+    case BFD_RELOC_XTENSA_PDIFF32:
+      TRACE ("BFD_RELOC_XTENSA_PDIFF32");
+      return &elf_howto_table[(unsigned) R_XTENSA_PDIFF32 ];
+
+    case BFD_RELOC_XTENSA_NDIFF8:
+      TRACE ("BFD_RELOC_XTENSA_NDIFF8");
+      return &elf_howto_table[(unsigned) R_XTENSA_NDIFF8 ];
+
+    case BFD_RELOC_XTENSA_NDIFF16:
+      TRACE ("BFD_RELOC_XTENSA_NDIFF16");
+      return &elf_howto_table[(unsigned) R_XTENSA_NDIFF16 ];
+
+    case BFD_RELOC_XTENSA_NDIFF32:
+      TRACE ("BFD_RELOC_XTENSA_NDIFF32");
+      return &elf_howto_table[(unsigned) R_XTENSA_NDIFF32 ];
+
     case BFD_RELOC_XTENSA_RTLD:
       TRACE ("BFD_RELOC_XTENSA_RTLD");
       return &elf_howto_table[(unsigned) R_XTENSA_RTLD ];
@@ -1851,6 +1889,12 @@ elf_xtensa_do_reloc (reloc_howto_type *howto,
     case R_XTENSA_DIFF8:
     case R_XTENSA_DIFF16:
     case R_XTENSA_DIFF32:
+    case R_XTENSA_PDIFF8:
+    case R_XTENSA_PDIFF16:
+    case R_XTENSA_PDIFF32:
+    case R_XTENSA_NDIFF8:
+    case R_XTENSA_NDIFF16:
+    case R_XTENSA_NDIFF32:
     case R_XTENSA_TLS_FUNC:
     case R_XTENSA_TLS_ARG:
     case R_XTENSA_TLS_CALL:
@@ -9604,7 +9648,13 @@ relax_section (bfd *abfd, asection *sec, struct bfd_link_info *link_info)
 
 	      if (r_type == R_XTENSA_DIFF8
 		  || r_type == R_XTENSA_DIFF16
-		  || r_type == R_XTENSA_DIFF32)
+		  || r_type == R_XTENSA_DIFF32
+		  || r_type == R_XTENSA_PDIFF8
+		  || r_type == R_XTENSA_PDIFF16
+		  || r_type == R_XTENSA_PDIFF32
+		  || r_type == R_XTENSA_NDIFF8
+		  || r_type == R_XTENSA_NDIFF16
+		  || r_type == R_XTENSA_NDIFF32)
 		{
 		  bfd_signed_vma diff_value = 0;
 		  bfd_vma new_end_offset, diff_mask = 0;
@@ -9631,8 +9681,27 @@ relax_section (bfd *abfd, asection *sec, struct bfd_link_info *link_info)
 		      diff_value =
 			bfd_get_signed_32 (abfd, &contents[old_source_offset]);
 		      break;
+		    case R_XTENSA_PDIFF8:
+		    case R_XTENSA_NDIFF8:
+		      diff_value =
+			bfd_get_8 (abfd, &contents[old_source_offset]);
+		      break;
+		    case R_XTENSA_PDIFF16:
+		    case R_XTENSA_NDIFF16:
+		      diff_value =
+			bfd_get_16 (abfd, &contents[old_source_offset]);
+		      break;
+		    case R_XTENSA_PDIFF32:
+		    case R_XTENSA_NDIFF32:
+		      diff_value =
+			bfd_get_32 (abfd, &contents[old_source_offset]);
+		      break;
 		    }
 
+		  if (r_type >= R_XTENSA_NDIFF8
+		      && r_type <= R_XTENSA_NDIFF32)
+		    diff_value = -diff_value;
+
 		  new_end_offset = offset_with_removed_text_map
 		    (&target_relax_info->action_list,
 		     r_rel.target_offset + diff_value);
@@ -9655,6 +9724,24 @@ relax_section (bfd *abfd, asection *sec, struct bfd_link_info *link_info)
 		      bfd_put_signed_32 (abfd, diff_value,
 				  &contents[old_source_offset]);
 		      break;
+		    case R_XTENSA_PDIFF8:
+		    case R_XTENSA_NDIFF8:
+		      diff_mask = 0xff;
+		      bfd_put_8 (abfd, diff_value,
+				 &contents[old_source_offset]);
+		      break;
+		    case R_XTENSA_PDIFF16:
+		    case R_XTENSA_NDIFF16:
+		      diff_mask = 0xffff;
+		      bfd_put_16 (abfd, diff_value,
+				  &contents[old_source_offset]);
+		      break;
+		    case R_XTENSA_PDIFF32:
+		    case R_XTENSA_NDIFF32:
+		      diff_mask = 0xffffffff;
+		      bfd_put_32 (abfd, diff_value,
+				  &contents[old_source_offset]);
+		      break;
 		    }
 
 		  /* Check for overflow. Sign bits must be all zeroes or all ones */
diff --git a/bfd/libbfd.h b/bfd/libbfd.h
index 348ccfd..6aeaf18 100644
--- a/bfd/libbfd.h
+++ b/bfd/libbfd.h
@@ -2919,6 +2919,12 @@ static const char *const bfd_reloc_code_real_names[] = { "@@uninitialized@@",
   "BFD_RELOC_XTENSA_TLS_FUNC",
   "BFD_RELOC_XTENSA_TLS_ARG",
   "BFD_RELOC_XTENSA_TLS_CALL",
+  "BFD_RELOC_XTENSA_PDIFF8",
+  "BFD_RELOC_XTENSA_PDIFF16",
+  "BFD_RELOC_XTENSA_PDIFF32",
+  "BFD_RELOC_XTENSA_NDIFF8",
+  "BFD_RELOC_XTENSA_NDIFF16",
+  "BFD_RELOC_XTENSA_NDIFF32",
   "BFD_RELOC_Z80_DISP8",
   "BFD_RELOC_Z80_BYTE0",
   "BFD_RELOC_Z80_BYTE1",
diff --git a/bfd/reloc.c b/bfd/reloc.c
index c4dec86..f5df8e2 100644
--- a/bfd/reloc.c
+++ b/bfd/reloc.c
@@ -6556,6 +6556,8 @@ ENUMX
 ENUMX
   BFD_RELOC_XTENSA_DIFF32
 ENUMDOC
+  Xtensa relocations for backward compatibility.  These have been replaced
+  by BFD_RELOC_XTENSA_PDIFF and BFD_RELOC_XTENSA_NDIFF.
   Xtensa relocations to mark the difference of two local symbols.
   These are only needed to support linker relaxation and can be ignored
   when not relaxing.  The field is set to the value of the difference
@@ -6668,6 +6670,28 @@ ENUMX
   BFD_RELOC_XTENSA_TLS_CALL
 ENUMDOC
   Xtensa TLS relocations.
+ENUM
+  BFD_RELOC_XTENSA_PDIFF8
+ENUMX
+  BFD_RELOC_XTENSA_PDIFF16
+ENUMX
+  BFD_RELOC_XTENSA_PDIFF32
+ENUMX
+  BFD_RELOC_XTENSA_NDIFF8
+ENUMX
+  BFD_RELOC_XTENSA_NDIFF16
+ENUMX
+  BFD_RELOC_XTENSA_NDIFF32
+ENUMDOC
+  Xtensa relocations to mark the difference of two local symbols.
+  These are only needed to support linker relaxation and can be ignored
+  when not relaxing.  The field is set to the value of the difference
+  assuming no relaxation.  The relocation encodes the position of the
+  subtracted symbol so the linker can determine whether to adjust the field
+  value.  PDIFF relocations are used for positive differences, NDIFF
+  relocations are used for negative differences.  The difference value
+  is treated as unsigned with these relocation types, giving full
+  8/16 value ranges.
 
 ENUM
   BFD_RELOC_Z80_DISP8