[BFD, AArch64, x86] Improve warning for --force-bti

The AArch64 linker option to turn on BTI (--force-bti) warns in case there are
input objects which have a missing GNU NOTE section for BTI. This patch is trying
to improve the warnings that come out.

In order to do so, I propose adding a new argument to elf_merge_gnu_properties
and the backend function merge_gnu_properties. This new argument makes sure
that we now pass both the objects along with the properties to which they
belong to. The x86 backend function has also been updated to match this
change.

*** bfd/ChangeLog ***

2019-03-21  Sudakshina Das  <sudi.das@arm.com>

	* elf-bfd.h (struct elf_backend_data): Add argument to
	merge_gnu_properties.
	* elf-properties.c (elf_merge_gnu_properties): Add argument to
	itself and while calling bed->merge_gnu_properties.
	(elf_merge_gnu_property_list): Update the calls for
	elf_merge_gnu_properties.
	* elfnn-aarch64.c (elfNN_aarch64_merge_gnu_properties): Update handling
	of --force-bti warning and add argument.
	* elfxx-aarch64.c (_bfd_aarch64_elf_link_setup_gnu_properties): Add
	warning.
	* elfxx-x86.c (_bfd_x86_elf_merge_gnu_properties): Add argument.
	* elfxx-x86.h (_bfd_x86_elf_merge_gnu_properties): Likewise in
	declaration.

*** ld/ChangeLog ***

2019-03-21  Sudakshina Das  <sudi.das@arm.com>

	* testsuite/ld-aarch64/aarch64-elf.exp: Add new test.
	* testsuite/ld-aarch64/bti-plt-1.s: Add .ifdef for PAC note section.
	* testsuite/ld-aarch64/bti-plt-6.d: Update warning.
	* testsuite/ld-aarch64/bti-plt-7.d: Likewise.
	* testsuite/ld-aarch64/bti-warn.d: New test.

6 files changed, 48 insertions, 4 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 6116ca6..2853c09 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,11 @@
+2019-03-21  Sudakshina Das  <sudi.das@arm.com>
+
+	* testsuite/ld-aarch64/aarch64-elf.exp: Add new test.
+	* testsuite/ld-aarch64/bti-plt-1.s: Add .ifdef for PAC note section.
+	* testsuite/ld-aarch64/bti-plt-6.d: Update warning.
+	* testsuite/ld-aarch64/bti-plt-7.d: Likewise.
+	* testsuite/ld-aarch64/bti-warn.d: New test.
+
 2019-03-21  Alan Modra  <amodra@gmail.com>
 
 	* testsuite/ld-elf/fini2.s: Reduce alignment.
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index 12c2d97..ba3ce36 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -407,3 +407,5 @@ run_dump_test "pac-plt-1"
 run_dump_test "pac-plt-2"
 run_dump_test "bti-pac-plt-1"
 run_dump_test "bti-pac-plt-2"
+
+run_dump_test "bti-warn"
diff --git a/ld/testsuite/ld-aarch64/bti-plt-1.s b/ld/testsuite/ld-aarch64/bti-plt-1.s
index b798ca4..8bb39c4 100644
--- a/ld/testsuite/ld-aarch64/bti-plt-1.s
+++ b/ld/testsuite/ld-aarch64/bti-plt-1.s
@@ -21,3 +21,20 @@ _start:
 	.p2align 3
 5:
 .endif
+.ifdef __property_pac__
+	.section ".note.gnu.property", "a"
+	.p2align 3
+	.long 1f - 0f		/* name length */
+	.long 5f - 2f		/* data length */
+	.long 5			/* note type */
+0:	.asciz "GNU"		/* vendor name */
+1:
+	.p2align 3
+2:	.long 0xc0000000	/* pr_type.  */
+	.long 4f - 3f		/* pr_datasz.  */
+3:
+	.long 0x2		/* PAC.  */
+4:
+	.p2align 3
+5:
+.endif
diff --git a/ld/testsuite/ld-aarch64/bti-plt-6.d b/ld/testsuite/ld-aarch64/bti-plt-6.d
index c7d5169..30d225d 100644
--- a/ld/testsuite/ld-aarch64/bti-plt-6.d
+++ b/ld/testsuite/ld-aarch64/bti-plt-6.d
@@ -1,9 +1,9 @@
 #name: Warn with one missing GNU NOTE BTI input
-#source: property-bti-pac1.s
 #source: property-bti-pac2.s
+#source: property-bti-pac1.s
 #as: -mabi=lp64 -defsym __property_pac__=1
 #ld: -shared --force-bti
-#warning: .*: warning: BTI turned on by --force-bti.*$
+#warning: .*property-bti-pac2.*: warning: BTI turned on by --force-bti.*$
 #readelf: -n
 
 # Should warn about the missing input BTI NOTE but should
diff --git a/ld/testsuite/ld-aarch64/bti-plt-7.d b/ld/testsuite/ld-aarch64/bti-plt-7.d
index 625f284..e8fa0d3 100644
--- a/ld/testsuite/ld-aarch64/bti-plt-7.d
+++ b/ld/testsuite/ld-aarch64/bti-plt-7.d
@@ -1,9 +1,10 @@
 #name: Warn when neither inputs has GNU NOTE BTI
-#source: property-bti-pac1.s
+#source: property-bti-pac2.s
 #source: plt_mapping_symbol.s
 #as: -mabi=lp64
 #ld: -shared --force-bti
-#warning: .*: warning: BTI turned on by --force-bti.*$
+#warning: .*plt_mapping_symbol.*: warning: BTI turned on by --force-bti.*
+#warning: .*property-bti-pac2.*: warning: BTI turned on by --force-bti.*
 #readelf: -n
 
 # Should warn about the missing input BTI NOTE but should
diff --git a/ld/testsuite/ld-aarch64/bti-warn.d b/ld/testsuite/ld-aarch64/bti-warn.d
new file mode 100644
index 0000000..c2edccf
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/bti-warn.d
@@ -0,0 +1,16 @@
+#name: Warn when both have GNU prop but neither BTI
+#source: property-bti-pac2.s
+#source: bti-plt-1.s
+#as: -mabi=lp64 --defsym __guard_property_bti__=1 --defsym __property_pac__=1
+#ld: -shared --force-bti
+#warning: .*property-bti-pac2.*: warning: BTI turned on by --force-bti.*
+#warning: .*bti-plt-1.*: warning: BTI turned on by --force-bti.*
+#readelf: -n
+
+# Should warn about the missing input BTI NOTE but should
+# still mark output as BTI
+
+Displaying notes found in: .note.gnu.property
+  Owner                 Data size	Description
+  GNU                  0x00000010	NT_GNU_PROPERTY_TYPE_0
+      Properties: AArch64 feature: BTI, PAC