[ARM] Add TLS relocations for FDPIC.

Define and handle TLS relocations for FDPIC in BFD and gas.

In gas, the new relocations are rejected if the --fdpic option was not
specified.

We also define the __tdata_start symbol to mark the start of the
.tdata section. This allows FDPIC static binaries to find the start of
.tdata section, since phdr->p_vaddr of TLS segment is not a valid
value for FDPIC.

2018-04-25  Christophe Lyon  <christophe.lyon@st.com>
	Mickaël Guêné  <mickael.guene@st.com>

	bfd/:
	* bfd-in2.h (BFD_RELOC_ARM_TLS_GD32_FDPIC)
	(BFD_RELOC_ARM_TLS_LDM32_FDPIC, BFD_RELOC_ARM_TLS_IE32_FDPIC): New
	relocations.
	* elf32-arm.c (elf32_arm_howto_table_2): Add R_ARM_TLS_GD32_FDPIC,
	R_ARM_TLS_LDM32_FDPIC, R_ARM_TLS_IE32_FDPIC relocations.
	(elf32_arm_reloc_map): Add R_ARM_TLS_GD32_FDPIC,
	R_ARM_TLS_LDM32_FDPIC, R_ARM_TLS_IE32_FDPIC.
	(struct elf32_arm_link_hash_table): Update comment.
	(elf32_arm_final_link_relocate): Handle TLS FDPIC relocations.
	(IS_ARM_TLS_RELOC): Likewise.
	(elf32_arm_check_relocs): Likewise.
	(allocate_dynrelocs_for_symbol): Likewise.
	(elf32_arm_size_dynamic_sections): Update comment.
	* reloc.c: Add BFD_RELOC_ARM_TLS_GD32_FDPIC,
	BFD_RELOC_ARM_TLS_LDM32_FDPIC, BFD_RELOC_ARM_TLS_IE32_FDPIC.

	gas/
	* config/tc-arm.c (reloc_names): Add TLSGD_FDPIC, TLSLDM_FDPIC,
	GOTTPOFF_FDIC relocations.
	(md_apply_fix): Handle the new TLS FDPIC relocations.
	(tc_gen_reloc): Likewise.
	(arm_fix_adjustable): Likewise.

	include/
	* elf/arm.h: Add R_ARM_TLS_GD32_FDPIC, R_ARM_TLS_LDM32_FDPIC,
	R_ARM_TLS_IE32_FDPIC.

	ld/
	* scripttempl/elf.sc: Define __tdata_start for .tdata section.

2 files changed, 34 insertions, 1 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 122daaa..ce832e9 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,6 +1,15 @@
 2018-04-25  Christophe Lyon  <christophe.lyon@st.com>
 	Mickaël Guêné  <mickael.guene@st.com>
 
+	* config/tc-arm.c (reloc_names): Add TLSGD_FDPIC, TLSLDM_FDPIC,
+	GOTTPOFF_FDIC relocations.
+	(md_apply_fix): Handle the new TLS FDPIC relocations.
+	(tc_gen_reloc): Likewise.
+	(arm_fix_adjustable): Likewise.
+
+2018-04-25  Christophe Lyon  <christophe.lyon@st.com>
+	Mickaël Guêné  <mickael.guene@st.com>
+
 	* config/tc-arm.c (reloc_names): Add gotfuncdesc, gotofffuncdesc,
 	funcdesc.
 	(md_apply_fix): Support the new relocations.
diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index 33a88bb..760afab 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -19309,7 +19309,10 @@ static struct reloc_entry reloc_names[] =
   { "gotofffuncdesc", BFD_RELOC_ARM_GOTOFFFUNCDESC },
 	{ "GOTOFFFUNCDESC", BFD_RELOC_ARM_GOTOFFFUNCDESC },
   { "funcdesc", BFD_RELOC_ARM_FUNCDESC },
-	{ "FUNCDESC", BFD_RELOC_ARM_FUNCDESC }
+	{ "FUNCDESC", BFD_RELOC_ARM_FUNCDESC },
+   { "tlsgd_fdpic", BFD_RELOC_ARM_TLS_GD32_FDPIC },      { "TLSGD_FDPIC", BFD_RELOC_ARM_TLS_GD32_FDPIC },
+   { "tlsldm_fdpic", BFD_RELOC_ARM_TLS_LDM32_FDPIC },    { "TLSLDM_FDPIC", BFD_RELOC_ARM_TLS_LDM32_FDPIC },
+   { "gottpoff_fdpic", BFD_RELOC_ARM_TLS_IE32_FDPIC },   { "GOTTPOFF_FDIC", BFD_RELOC_ARM_TLS_IE32_FDPIC },
 };
 #endif
 
@@ -23982,6 +23985,21 @@ md_apply_fix (fixS *	fixP,
       S_SET_THREAD_LOCAL (fixP->fx_addsy);
       break;
 
+      /* Same handling as above, but with the arm_fdpic guard.  */
+    case BFD_RELOC_ARM_TLS_GD32_FDPIC:
+    case BFD_RELOC_ARM_TLS_IE32_FDPIC:
+    case BFD_RELOC_ARM_TLS_LDM32_FDPIC:
+      if (arm_fdpic)
+	{
+	  S_SET_THREAD_LOCAL (fixP->fx_addsy);
+	}
+      else
+	{
+	  as_bad_where (fixP->fx_file, fixP->fx_line,
+			_("Relocation supported only in FDPIC mode"));
+	}
+      break;
+
     case BFD_RELOC_ARM_GOT32:
     case BFD_RELOC_ARM_GOTOFF:
       break;
@@ -24783,9 +24801,12 @@ tc_gen_reloc (asection *section, fixS *fixp)
 
     case BFD_RELOC_ARM_TLS_GOTDESC:
     case BFD_RELOC_ARM_TLS_GD32:
+    case BFD_RELOC_ARM_TLS_GD32_FDPIC:
     case BFD_RELOC_ARM_TLS_LE32:
     case BFD_RELOC_ARM_TLS_IE32:
+    case BFD_RELOC_ARM_TLS_IE32_FDPIC:
     case BFD_RELOC_ARM_TLS_LDM32:
+    case BFD_RELOC_ARM_TLS_LDM32_FDPIC:
       /* BFD will include the symbol's address in the addend.
 	 But we don't want that, so subtract it out again here.  */
       if (!S_IS_COMMON (fixp->fx_addsy))
@@ -25051,9 +25072,12 @@ arm_fix_adjustable (fixS * fixP)
       || fixP->fx_r_type == BFD_RELOC_ARM_GOT32
       || fixP->fx_r_type == BFD_RELOC_ARM_GOTOFF
       || fixP->fx_r_type == BFD_RELOC_ARM_TLS_GD32
+      || fixP->fx_r_type == BFD_RELOC_ARM_TLS_GD32_FDPIC
       || fixP->fx_r_type == BFD_RELOC_ARM_TLS_LE32
       || fixP->fx_r_type == BFD_RELOC_ARM_TLS_IE32
+      || fixP->fx_r_type == BFD_RELOC_ARM_TLS_IE32_FDPIC
       || fixP->fx_r_type == BFD_RELOC_ARM_TLS_LDM32
+      || fixP->fx_r_type == BFD_RELOC_ARM_TLS_LDM32_FDPIC
       || fixP->fx_r_type == BFD_RELOC_ARM_TLS_LDO32
       || fixP->fx_r_type == BFD_RELOC_ARM_TLS_GOTDESC
       || fixP->fx_r_type == BFD_RELOC_ARM_TLS_CALL