fix

bfd/elf64-x86-64.c

Index: bfd/elf64-x86-64.c
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index bb76be6e4fa857fd15801fab1e29a06809062fb2..63f1b0be1264d2910bbf379ef4991df72b3bd721 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -900,6 +900,14 @@ elf64_x86_64_check_tls_transition (bfd *abfd, asection *sec,
       if ((rel + 1) >= relend)
 	return FALSE;
 
+      /* Check transition from GD or LD access model.
+	    lea foo@tlsgd/tlsld(%rip), %rdi
+	    nop*      
+	    call __tls_get_addr
+	 can transit to different access model.  */
+
+      /* NACLHACK: we hope for the best and check nothing!  */
+#if 0
       if (r_type == R_X86_64_TLSGD)
 	{
 	  /* Check transition from GD access model.  Only
@@ -933,6 +941,7 @@ elf64_x86_64_check_tls_transition (bfd *abfd, asection *sec,
 	  if (op.i != ld.i)
 	    return FALSE;
 	}
+#endif
 
       r_symndx = ELF64_R_SYM (rel[1].r_info);
       if (r_symndx < symtab_hdr->sh_info)
@@ -976,6 +985,7 @@ elf64_x86_64_check_tls_transition (bfd *abfd, asection *sec,
       val = bfd_get_8 (abfd, contents + offset - 2);
       if (val != 0x8b && val != 0x03)
 	return FALSE;
+#endif
 
       val = bfd_get_8 (abfd, contents + offset - 1);
       return (val & 0xc7) == 5;
@@ -1139,6 +1149,28 @@ elf64_x86_64_tls_transition (struct bfd_link_info *info, bfd *abfd,
   return TRUE;
 }
 
+/* NACLHACK: add reference to __nacl_add_tp (or __nacl_read_tp) symbol.  */
+static struct elf_link_hash_entry *
+nacl_add_tp_symbol (struct bfd_link_info *info, const char* name)
+{
+  struct elf_link_hash_entry *h;
+  struct bfd_link_hash_entry *bh = NULL;
+
+  if (!(_bfd_generic_link_add_one_symbol
+        (info, info->output_bfd, name, BSF_GLOBAL,
+         bfd_und_section_ptr, (bfd_vma) 0, NULL, TRUE,
+         FALSE, &bh)))
+    return NULL;
+
+  h = (struct elf_link_hash_entry *) bh;
+  h->needs_plt = 1;
+  h->plt.refcount += 1;
+  return h;
+}
+
+static struct elf_link_hash_entry *nacl_add_tp_entry = NULL;
+static struct elf_link_hash_entry *nacl_read_tp_entry = NULL;
+
 /* Look through the relocs for a section during the first phase, and
    calculate needed space in the global offset table, procedure
    linkage table, and dynamic reloc sections.  */
@@ -2660,6 +2692,9 @@ elf64_x86_64_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
   Elf_Internal_Rela *rel;
   Elf_Internal_Rela *relend;
 
+  /* NACLHACK: new variable for NACL rewrites.  */
+  struct elf_link_hash_entry *h_subst = NULL;
+
   BFD_ASSERT (is_x86_64_elf (input_bfd));
 
   htab = elf64_x86_64_hash_table (info);
@@ -2726,6 +2761,27 @@ elf64_x86_64_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 	      h->root.u.def.section = sec;
 	    }
 	}
+      else if (h_subst)
+	{
+	  /* NACLHACK: Replace symbol to relocate.
+
+	     This is somewhat hacky, as relies on not using r_symndx any more,
+	     which is currently true for R_X86_64_PLT32 involved in NaCl TLS
+	     code sequences.
+
+	     Doing this in a more reliable way means either splitting this
+	     glorious function or copy-pasting code that processes relocations
+	     of interest. Any volunteers?  */
+
+	  bfd_boolean warned;
+
+	  h = h_subst;
+	  h_subst = NULL;
+
+	  RELOC_FOR_GLOBAL_SYM_HASH (info, input_bfd, input_section, rel,
+				     h, sec, relocation,
+				     unresolved_reloc, warned);
+	}
       else
 	{
 	  bfd_boolean warned;
@@ -3380,6 +3436,7 @@ elf64_x86_64_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 			      contents + roff + 8);
 		  /* Skip R_X86_64_PC32/R_X86_64_PLT32.  */
 		  rel++;
+#endif
 		  continue;
 		}
 	      else if (ELF64_R_TYPE (rel->r_info) == R_X86_64_GOTPC32_TLSDESC)
@@ -3628,6 +3685,7 @@ elf64_x86_64_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 			      contents + roff + 8);
 		  /* Skip R_X86_64_PLT32.  */
 		  rel++;
+#endif
 		  continue;
 		}
 	      else if (ELF64_R_TYPE (rel->r_info) == R_X86_64_GOTPC32_TLSDESC)
@@ -3694,6 +3752,15 @@ elf64_x86_64_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 
 	  if (r_type != R_X86_64_TLSLD)
 	    {
+	      /*  NACLHACK: use __nacl_add_tp instead of __tls_get_addr.  */
+	      /* Rewrite lea to nop.  */
+	      memcpy (contents + rel->r_offset - 3,
+		      "\x0f\x1f\x80\x00\x00\x00\x00", 7);
+
+	      /* Call __nacl_read_tp instead of __tls_get_addr.  */
+	      h_subst = nacl_read_tp_entry;
+#if 0
+	      /* NACLHACK: Original LD->LE transition disabled.  */
 	      /* LD->LE transition:
 		 leaq foo@tlsld(%rip), %rdi; call __tls_get_addr.
 		 We change it into:
@@ -3704,6 +3771,7 @@ elf64_x86_64_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 		      "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0", 12);
 	      /* Skip R_X86_64_PC32/R_X86_64_PLT32.  */
 	      rel++;
+#endif
 	      continue;
 	    }