[patch] Thumb entry points

[Paul Brook <paul at codesourcery dot com>]

The attached patch makes the Arm linker set the low bit of the entry point 
address when the symbol is a Thumb function.

Tested with cross to arm-none-eabi
Ok?

Paul

2006-02-04  Paul Brook  <paul@codesourcery.com>

ld/
	* emultempl/armelf.em: Include elf/arm.h.
	(arm_elf_finish): Set low address bit if enty point is a Thumb
	function.
ld/testsuite/
	* ld-arm/arm-elf.exp: Add thumb-entry test.
	* ld-arm/thumb-entry.d: New test.
	* ld-arm/thumb-entry.s: New test.

Index: ld/emultempl/armelf.em
===================================================================
RCS file: /var/cvsroot/src-cvs/src/ld/emultempl/armelf.em,v
retrieving revision 1.48
diff -u -p -r1.48 armelf.em
--- ld/emultempl/armelf.em	17 Nov 2005 00:10:05 -0000	1.48
+++ ld/emultempl/armelf.em	4 Feb 2006 02:53:53 -0000
@@ -26,6 +26,8 @@
 test -z "$TARGET2_TYPE" && TARGET2_TYPE="rel"
 cat >>e${EMULATION_NAME}.c <<EOF
 
+#include "elf/arm.h"
+
 static char *thumb_entry_symbol = NULL;
 static bfd *bfd_for_interwork;
 static int byteswap_code = 0;
@@ -150,11 +152,25 @@ arm_elf_finish (void)
   /* Call the elf32.em routine.  */
   gld${EMULATION_NAME}_finish ();
 
-  if (thumb_entry_symbol == NULL)
-    return;
+  if (thumb_entry_symbol)
+    {
+      h = bfd_link_hash_lookup (link_info.hash, thumb_entry_symbol,
+				FALSE, FALSE, TRUE);
+    }
+  else
+    {
+      struct elf_link_hash_entry * eh;
+
+      if (!entry_symbol.name)
+	return;
+
+      h = bfd_link_hash_lookup (link_info.hash, entry_symbol.name,
+				FALSE, FALSE, TRUE);
+      eh = (struct elf_link_hash_entry *)h;
+      if (!h || ELF_ST_TYPE(eh->type) != STT_ARM_TFUNC)
+	return;
+    }
 
-  h = bfd_link_hash_lookup (link_info.hash, thumb_entry_symbol,
-			    FALSE, FALSE, TRUE);
 
   if (h != (struct bfd_link_hash_entry *) NULL
       && (h->type == bfd_link_hash_defined
@@ -180,7 +196,8 @@ arm_elf_finish (void)
 
       sprintf_vma (buffer + 2, val);
 
-      if (entry_symbol.name != NULL && entry_from_cmdline)
+      if (thumb_entry_symbol != NULL && entry_symbol.name != NULL
+	  && entry_from_cmdline)
 	einfo (_("%P: warning: '--thumb-entry %s' is overriding '-e %s'\n"),
 	       thumb_entry_symbol, entry_symbol.name);
       entry_symbol.name = buffer;
Index: ld/testsuite/ld-arm/arm-elf.exp
===================================================================
RCS file: /var/cvsroot/src-cvs/src/ld/testsuite/ld-arm/arm-elf.exp,v
retrieving revision 1.9
diff -u -p -r1.9 arm-elf.exp
--- ld/testsuite/ld-arm/arm-elf.exp	12 Dec 2005 17:03:40 -0000	1.9
+++ ld/testsuite/ld-arm/arm-elf.exp	4 Feb 2006 02:47:51 -0000
@@ -89,6 +89,9 @@ set armelftests {
     {"TLS dynamic application" "-T arm-dyn.ld tmpdir/tls-lib.so" "" {tls-app.s}
      {{objdump -fdw tls-app.d} {objdump -Rw tls-app.r}}
      "tls-app"}
+    {"Thumb entry point" "-T arm.ld" "" {thumb-entry.s}
+     {{readelf -h thumb-entry.d}}
+     "thumb-entry"}
 }
 
 run_ld_link_tests $armelftests
Index: ld/testsuite/ld-arm/thumb-entry.d
===================================================================
RCS file: ld/testsuite/ld-arm/thumb-entry.d
diff -N ld/testsuite/ld-arm/thumb-entry.d
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-arm/thumb-entry.d	4 Feb 2006 02:31:13 -0000
@@ -0,0 +1,3 @@
+#...
+  Entry point address:               0x8001
+#...
Index: ld/testsuite/ld-arm/thumb-entry.s
===================================================================
RCS file: ld/testsuite/ld-arm/thumb-entry.s
diff -N ld/testsuite/ld-arm/thumb-entry.s
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-arm/thumb-entry.s	4 Feb 2006 02:32:17 -0000
@@ -0,0 +1,8 @@
+	.text
+	.arch armv4t
+	.thumb
+	.global _start
+	.thumb_func
+_start:
+	bx lr
+