PATCH: Allow building x32 DSO from x86-64 object file

["H.J. Lu" <hongjiu dot lu at intel dot com>]

Hi,

I found a need to build x32 DSO from x86-64 object file.  I checked
in this patch to support it.

H.J.
---
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index f9b3688..25fa50b 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,5 +1,11 @@
 2011-06-08  H.J. Lu  <hongjiu.lu@intel.com>
 
+	* elf64-x86-64.c (elf_x86_64_check_relocs): Allow R_X86_64_64
+	relocations in SEC_DEBUGGING sections when building shared
+	libraries.
+
+2011-06-08  H.J. Lu  <hongjiu.lu@intel.com>
+
 	PR ld/12851
 	* elflink.c (elf_gc_sweep): Don't check SHT_NOTE sections here.
 	(bfd_elf_gc_sections): Also check SHT_NOTE sections.
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 9d6d4a4..72a7cc1 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -1217,6 +1217,13 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	    break;
 
 	  case R_X86_64_64:
+	    /* Allow R_X86_64_64 relocations in SEC_DEBUGGING sections
+	       when building shared libraries.  */
+	    if (info->shared
+		&& !info->executable
+		&& (sec->flags & SEC_DEBUGGING) != 0)
+	      break;
+
 	  case R_X86_64_DTPOFF64:
 	  case R_X86_64_TPOFF64:
 	  case R_X86_64_PC64:
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index dcefc10..93096b0 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,5 +1,13 @@
 2011-06-08  H.J. Lu  <hongjiu.lu@intel.com>
 
+	* ld-x86-64/simple.c: New.
+	* ld-x86-64/x86-64-x32.rd: Likewise.
+
+	* ld-x86-64/x86-64.exp: Check building x32 DSO from x86-64
+	object file.
+
+2011-06-08  H.J. Lu  <hongjiu.lu@intel.com>
+
 	PR ld/12851
 	* ld-elf/pr12851.d: New.
 	* ld-elf/pr12851.s: Likewise.
diff --git a/ld/testsuite/ld-x86-64/simple.c b/ld/testsuite/ld-x86-64/simple.c
new file mode 100644
index 0000000..4ce3e8f
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/simple.c
@@ -0,0 +1,5 @@
+int
+foo (int x)
+{
+  return x * 4;
+}
diff --git a/ld/testsuite/ld-x86-64/x86-64-x32.rd b/ld/testsuite/ld-x86-64/x86-64-x32.rd
new file mode 100644
index 0000000..7118cb9
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/x86-64-x32.rd
@@ -0,0 +1,5 @@
+Symbol table '\.dynsym' contains [0-9]+ entries:
+ +Num: +Value +Size Type +Bind +Vis +Ndx Name
+#...
+ +[0-9]+: +[0-9a-f]+ +[0-9a-f]+ +FUNC +GLOBAL +DEFAULT +[0-9]+ +foo
+#...
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index c77640b..8d4ed2c 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -203,3 +203,26 @@ run_dump_test "ia32-3"
 run_dump_test "lp64-1"
 run_dump_test "lp64-2"
 run_dump_test "lp64-3"
+
+# Need the C compiler
+if { [which $CC] != 0 } {
+    run_cc_link_tests {
+	{"Helper X32 DSO from x86-64 object" "" "-m64 -fPIC -g"
+	 {simple.c} {} "libsimple.a"}
+    }
+
+    set convertx32 "$objcopy -O elf32-x86-64 tmpdir/simple.o tmpdir/simple-x32.o"
+    send_log "$convertx32\n"
+    set got [remote_exec host "$convertx32"]
+    if { [lindex $got 0] != 0 || ![string match "" [lindex $got 1]] } then {
+	send_log "$got\n"
+	fail "Convert x86-64 object to x32"
+	return
+    }
+
+    run_ld_link_tests {
+	{"X32 DSO from x86-64 object"
+	 "-shared -melf32_x86_64 tmpdir/simple-x32.o" "--x32"
+	{dummy.s} {{readelf {-s --wide} x86-64-x32.rd}} "x86-64-x32"}
+    }
+}