Commit: Fix unsigned vs signed comparisons in SH code

[Alan Modra]

On Tue, Nov 26, 2019 at 02:06:16PM +0000, Nick Clifton wrote:
> -      if (sym_value < (bfd_vma) -0x1000 || sym_value >= 0x1000)
> +      if ((bfd_signed_vma) sym_value < -0x1000 || sym_value >= 0x1000)

Presumably the idea is to check for the range [-0x1000,0x1000).  This
still isn't correct.  sym_value >= 0x1000 is true for 0x1000 to
0xff..ffff.  (And I guess clang ought to complain that this test
subsumes the sym_value < -0x1000 test.)

Huh, but there are more bugs here.

      sym_value += (insn & 0xfff) << 1;
      if (insn & 0x800)
	sym_value -= 0x1000;
      insn = (insn & 0xf000) | (sym_value & 0xfff);

Pull a value out of the insn, shift it left, then put it back?
There's a missing shift right here.

I'm about to apply the following patch.

Using bfd_vma for insn is to avoid having to worry about sign
propagation in expressions involving insn and sym_value when bfd_vma
is not the same as unsigned long.

	* elf32-sh.c (sh_reloc): Use a bfd_vma insn.
	(sh_reloc <R_SH_IND12W>): Divide calculated relocation value
	by two before applying to insn.  Correct overflow test.
	* coff-sh.c (sh_reloc): Likewise.

diff --git a/bfd/coff-sh.c b/bfd/coff-sh.c
index 1077a20e6c..e1bfaf0a04 100644
--- a/bfd/coff-sh.c
+++ b/bfd/coff-sh.c
@@ -567,7 +567,7 @@ sh_reloc (bfd *      abfd,
 	  bfd *      output_bfd,
 	  char **    error_message ATTRIBUTE_UNUSED)
 {
-  unsigned long insn;
+  bfd_vma insn;
   bfd_vma sym_value;
   unsigned short r_type;
   bfd_vma addr = reloc_entry->address;
@@ -610,14 +610,14 @@ sh_reloc (bfd *      abfd,
 #endif
       insn = bfd_get_32 (abfd, hit_data);
       insn += sym_value + reloc_entry->addend;
-      bfd_put_32 (abfd, (bfd_vma) insn, hit_data);
+      bfd_put_32 (abfd, insn, hit_data);
       break;
 #ifdef COFF_WITH_PE
     case R_SH_IMAGEBASE:
       insn = bfd_get_32 (abfd, hit_data);
       insn += sym_value + reloc_entry->addend;
       insn -= pe_data (input_section->output_section->owner)->pe_opthdr.ImageBase;
-      bfd_put_32 (abfd, (bfd_vma) insn, hit_data);
+      bfd_put_32 (abfd, insn, hit_data);
       break;
 #endif
     case R_SH_PCDISP:
@@ -627,12 +627,10 @@ sh_reloc (bfd *      abfd,
 		    + input_section->output_offset
 		    + addr
 		    + 4);
-      sym_value += (insn & 0xfff) << 1;
-      if (insn & 0x800)
-	sym_value -= 0x1000;
-      insn = (insn & 0xf000) | (sym_value & 0xfff);
-      bfd_put_16 (abfd, (bfd_vma) insn, hit_data);
-      if ((bfd_signed_vma) sym_value < -0x1000 || sym_value >= 0x1000)
+      sym_value += (((insn & 0xfff) ^ 0x800) - 0x800) << 1;
+      insn = (insn & 0xf000) | ((sym_value >> 1) & 0xfff);
+      bfd_put_16 (abfd, insn, hit_data);
+      if (sym_value + 0x1000 >= 0x2000 || (sym_value & 1) != 0)
 	return bfd_reloc_overflow;
       break;
     default:
diff --git a/bfd/elf32-sh.c b/bfd/elf32-sh.c
index 863e2e1bfc..be4256c585 100644
--- a/bfd/elf32-sh.c
+++ b/bfd/elf32-sh.c
@@ -232,7 +232,7 @@ sh_elf_reloc (bfd *abfd, arelent *reloc_entry, asymbol *symbol_in,
 	      void *data, asection *input_section, bfd *output_bfd,
 	      char **error_message ATTRIBUTE_UNUSED)
 {
-  unsigned long insn;
+  bfd_vma insn;
   bfd_vma sym_value;
   enum elf_sh_reloc_type r_type;
   bfd_vma addr = reloc_entry->address;
@@ -274,7 +274,7 @@ sh_elf_reloc (bfd *abfd, arelent *reloc_entry, asymbol *symbol_in,
     case R_SH_DIR32:
       insn = bfd_get_32 (abfd, hit_data);
       insn += sym_value + reloc_entry->addend;
-      bfd_put_32 (abfd, (bfd_vma) insn, hit_data);
+      bfd_put_32 (abfd, insn, hit_data);
       break;
     case R_SH_IND12W:
       insn = bfd_get_16 (abfd, hit_data);
@@ -283,12 +283,10 @@ sh_elf_reloc (bfd *abfd, arelent *reloc_entry, asymbol *symbol_in,
 		    + input_section->output_offset
 		    + addr
 		    + 4);
-      sym_value += (insn & 0xfff) << 1;
-      if (insn & 0x800)
-	sym_value -= 0x1000;
-      insn = (insn & 0xf000) | (sym_value & 0xfff);
-      bfd_put_16 (abfd, (bfd_vma) insn, hit_data);
-      if ((bfd_signed_vma) sym_value < -0x1000 || sym_value >= 0x1000)
+      sym_value += (((insn & 0xfff) ^ 0x800) - 0x800) << 1;
+      insn = (insn & 0xf000) | ((sym_value >> 1) & 0xfff);
+      bfd_put_16 (abfd, insn, hit_data);
+      if (sym_value + 0x1000 >= 0x2000 || (sym_value & 1) != 0)
 	return bfd_reloc_overflow;
       break;
     default:


-- 
Alan Modra
Australia Development Lab, IBM