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PATCH: Properly handle protected function for ia32 and x86_64


On Thu, Jan 20, 2005 at 09:33:54AM -0800, H. J. Lu wrote:
> On Thu, Jan 20, 2005 at 11:17:55AM +0100, Andreas Schwab wrote:
> > "H. J. Lu" <hjl@lucon.org> writes:
> > 
> > > I don't think we should worry about anything, like wrong insn, r_offset
> > > == 0, jump table or data section.
> > 
> > At least we shouldn't crash.
> 
> How about this patch?
> 
> 

I updated the patch to make ia32 and x86_64 the same in dealing with
protected function symbols. On ia32, I disallow R_386_GOTOFF on
protected function and on x86_64, I allow 32bit relative branch on
protected function. Since we only warn global symbols, there is no
need to check if h is NULL. Also I updated error message.


H.J.
----
2005-01-24  H.J. Lu  <hongjiu.lu@intel.com>

	* elf32-i386.c (elf_i386_relocate_section): Disallow R_386_GOTOFF
	against protected function when building shared library.

	PR 584
	* elf64-x86-64.c (is_32bit_relative_branch): New.
	(elf64_x86_64_relocate_section): Alllow R_X86_64_PC32 on a
	protected function symbol when building shared library for
	32bit relative branch instruction.

--- bfd/elf32-i386.c.prot	2005-01-11 09:09:27.000000000 -0800
+++ bfd/elf32-i386.c	2005-01-24 12:52:26.233408808 -0800
@@ -2274,6 +2274,22 @@ elf_i386_relocate_section (bfd *output_b
 	  /* Relocation is relative to the start of the global offset
 	     table.  */
 
+	  /* Check to make sure it isn't a protected function symbol
+	     for shared library since it may not be local when used
+	     as function address.  */
+	  if (info->shared
+	      && h
+	      && h->def_regular
+	      && h->type == STT_FUNC
+	      && ELF_ST_VISIBILITY (h->other) == STV_PROTECTED)
+	    {
+	      (*_bfd_error_handler)
+		(_("%B: relocation R_386_GOTOFF against protected function `%s' can not be used when making a shared object"),
+		 input_bfd, h->root.root.string);
+	      bfd_set_error (bfd_error_bad_value);
+	      return FALSE;
+	    }
+
 	  /* Note that sgot is not involved in this
 	     calculation.  We always want the start of .got.plt.  If we
 	     defined _GLOBAL_OFFSET_TABLE_ in a different way, as is
--- bfd/elf64-x86-64.c.prot	2005-01-11 09:10:28.000000000 -0800
+++ bfd/elf64-x86-64.c	2005-01-24 13:08:28.622633929 -0800
@@ -1745,6 +1745,24 @@ tpoff (struct bfd_link_info *info, bfd_v
   return address - htab->tls_size - htab->tls_sec->vma;
 }
 
+/* Is the instruction before OFFSET in CONTENTS a 32bit relative
+   branch?  */
+
+static bfd_boolean
+is_32bit_relative_branch (bfd_byte *contents, bfd_vma offset)
+{
+  /* Opcode		Instruction
+     0xe8		call
+     0xe9		jump
+     0x0f 0x8x		conditional jump */
+  return ((offset > 0
+	   && (contents [offset - 1] == 0xe8
+	       || contents [offset - 1] == 0xe9))
+	  || (offset > 1
+	      && contents [offset - 2] == 0x0f
+	      && (contents [offset - 1] & 0xf0) == 0x80));
+}
+
 /* Relocate an x86_64 ELF section.  */
 
 static bfd_boolean
@@ -1950,13 +1968,26 @@ elf64_x86_64_relocate_section (bfd *outp
 	  if (info->shared
 	      && !SYMBOL_REFERENCES_LOCAL (info, h)
 	      && (input_section->flags & SEC_ALLOC) != 0
-	      && (input_section->flags & SEC_READONLY) != 0)
+	      && (input_section->flags & SEC_READONLY) != 0
+	      && (!h->def_regular
+		  || r_type != R_X86_64_PC32
+		  || h->type != STT_FUNC
+		  || ELF_ST_VISIBILITY (h->other) != STV_PROTECTED
+		  || !is_32bit_relative_branch (contents,
+						rel->r_offset)))
 	    {
-	      (*_bfd_error_handler)
-		(_("%B: relocation %s against `%s' can not be used when making a shared object; recompile with -fPIC"),
-		 input_bfd,
-		 x86_64_elf_howto_table[r_type].name,
-		 (h) ? h->root.root.string : "a local symbol");
+	      if (h->def_regular
+		  && r_type == R_X86_64_PC32
+		  && h->type == STT_FUNC
+		  && ELF_ST_VISIBILITY (h->other) == STV_PROTECTED)
+		(*_bfd_error_handler)
+		   (_("%B: relocation R_X86_64_PC32 against protected function `%s' can not be used when making a shared object"),
+		    input_bfd, h->root.root.string);
+	      else
+		(*_bfd_error_handler)
+		  (_("%B: relocation %s against `%s' can not be used when making a shared object; recompile with -fPIC"),
+		   input_bfd, x86_64_elf_howto_table[r_type].name,
+		   h->root.root.string);
 	      bfd_set_error (bfd_error_bad_value);
 	      return FALSE;
 	    }


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