Make import libraries relocatable objects

For ELF targets --out-implib currently generates an executable file
(e_type is ET_EXEC) despite the file being expected to be linked against
some other object file to make an executable later. It seems therefore
more sensible to make the import library a relocatable object file
(e_type set to ET_REL).

Incidentally, as dicted by requirement 8 of
"ARM v8-M Security Extensions: Requirements on Development Tools"
(document ARM-ECM-0359818) version 1.0, import libraries generated when
using --cmse-implib *must* be relocatable object file so this commit
also adds an assert there in case the type of ELF import library is
changed again in the future.

2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	Backport from mainline
	2017-05-08  Thomas Preud'homme  <thomas.preudhomme@arm.com>

bfd/
	* elflink.c (elf_output_implib): Remove executable flag from import
	library bfd.
	* elf32-arm.c (elf32_arm_filter_implib_symbols): Assert that the import
	library is a relocatable object file.

gas/
	* testsuite/ld-arm/arm-elf.exp
	(Secure gateway import library generation): Check e_type field
	of import library and executable produced.
	* testsuite/ld-arm/cmse-implib.type: Expectations for e_type field.

6 files changed, 37 insertions, 2 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 7d7416941fd..cae30e6b20e 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,13 @@
+2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	Backport from mainline
+	2017-05-08  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	* elflink.c (elf_output_implib): Remove executable flag from import
+	library bfd.
+	* elf32-arm.c (elf32_arm_filter_implib_symbols): Assert that the import
+	library is a relocatable object file.
+
 2017-06-13  Nick Clifton  <nickc@redhat.com>
 
 	Import this fix from the mainline sources:
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index cc8fd15cade..90286a84fa6 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -17500,6 +17500,10 @@ elf32_arm_filter_implib_symbols (bfd *abfd ATTRIBUTE_UNUSED,
 {
   struct elf32_arm_link_hash_table *globals = elf32_arm_hash_table (info);
 
+  /* Requirement 8 of "ARM v8-M Security Extensions: Requirements on
+     Development Tools" (ARM-ECM-0359818) mandates Secure Gateway import
+     library to be a relocatable object file.  */
+  BFD_ASSERT (!(bfd_get_file_flags (info->out_implib_bfd) & EXEC_P));
   if (globals->cmse_implib)
     return elf32_arm_filter_cmse_symbols (abfd, info, syms, symcount);
   else
diff --git a/bfd/elflink.c b/bfd/elflink.c
index cd03a137577..f82bd8202ba 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -11146,10 +11146,11 @@ elf_output_implib (bfd *abfd, struct bfd_link_info *info)
   if (!bfd_set_format (implib_bfd, bfd_object))
     return FALSE;
 
+  /* Use flag from executable but make it a relocatable object.  */
   flags = bfd_get_file_flags (abfd);
   flags &= ~HAS_RELOC;
   if (!bfd_set_start_address (implib_bfd, 0)
-      || !bfd_set_file_flags (implib_bfd, flags))
+      || !bfd_set_file_flags (implib_bfd, flags & ~EXEC_P))
     return FALSE;
 
   /* Copy architecture of output file to import library file.  */
diff --git a/gas/ChangeLog b/gas/ChangeLog
index a05355a1484..e75237552bb 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,13 @@
+2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	Backport from mainline
+	2017-05-08  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	* testsuite/ld-arm/arm-elf.exp
+	(Secure gateway import library generation): Check e_type field
+	of import library and executable produced.
+	* testsuite/ld-arm/cmse-implib.type: Expectations for e_type field.
+
 2017-06-05  Alan Modra  <amodra@gmail.com>
 
 	Apply from master
diff --git a/ld/testsuite/ld-arm/arm-elf.exp b/ld/testsuite/ld-arm/arm-elf.exp
index 1a4d262e608..2e193324907 100644
--- a/ld/testsuite/ld-arm/arm-elf.exp
+++ b/ld/testsuite/ld-arm/arm-elf.exp
@@ -685,7 +685,8 @@ set armeabitests_nonacl {
      "--section-start .gnu.sgstubs=0x20000 --out-implib=tmpdir/cmse-implib.lib --cmse-implib" ""
      "-march=armv8-m.base -mthumb --defsym VER=1"
      {cmse-implib.s}
-     {{readelf {-s tmpdir/cmse-implib.lib} cmse-implib.rd}}
+     {{readelf {-s tmpdir/cmse-implib.lib} cmse-implib.rd}
+      {readelf {-h tmpdir/cmse-implib.lib} cmse-implib.type}}
      "cmse-implib"}
     {"Input secure gateway import library"
      "--section-start .gnu.sgstubs=0x20000 --out-implib=tmpdir/cmse-new-implib.lib --in-implib=tmpdir/cmse-implib.lib --cmse-implib" ""
diff --git a/ld/testsuite/ld-arm/cmse-implib.type b/ld/testsuite/ld-arm/cmse-implib.type
new file mode 100644
index 00000000000..7bb3bccc8e5
--- /dev/null
+++ b/ld/testsuite/ld-arm/cmse-implib.type
@@ -0,0 +1,9 @@
+#...
+File: tmpdir/cmse-implib.lib
+#...
+[[:space:]]+Type:[[:space:]]+REL \(Relocatable file\)
+#...
+File: tmpdir/cmse-implib
+#...
+[[:space:]]+Type:[[:space:]]+EXEC \(Executable file\)
+#...