Emit a warning when -z relro is unsupported

ld silently accepts -z relro and -z norelro for targets that lack the
necessary GNU_RELRO support.  This patch makes those targets emit a
warning instead, and adds testsuite infrastructure to detect when
relro is unsupported.

binutils/
	* testsuite/config/default.exp (ld_elf_shared_opt): Don't set.
	* testsuite/lib/binutils-common.exp (check_relro_support): New proc.
	(run_dump_test): Use check_relro_support to decide whether to pass
	extra ld option "-z norelro".
ld/
	* emultempl/elf.em (gld${EMULATION_NAME}_handle_option): Omit
	-z relro and -z norelro when target support for GNU_RELRO is lacking.
	(gld${EMULATION_NAME}_before_parse): Ignore RELRO default too.
	* emultempl/aarch64elf.em (gld${EMULATION_NAME}_before_parse): Ignore
	RELRO default when target support for GNU_RELRO is lacking.
	* emultempl/armelf.em (gld${EMULATION_NAME}_before_parse): Likewise.
	* emultempl/linux.em (gld${EMULATION_NAME}_before_parse): Likewise.
	* emultempl/scoreelf.em (gld${EMULATION_NAME}_before_parse): Likewise.
	* testsuite/config/default.exp (ld_elf_shared_opt): Don't set.
	* testsuite/ld-elf/pr16322.d: xfail when no relro support.
	* testsuite/ld-elf/pr22393-1a.d: Likewise.
	* testsuite/ld-elf/pr22393-1b.d: Likewise.
	* testsuite/ld-elf/shared.exp (pr20995-2.so, pr20995-2): Likewise.
	* testsuite/lib/ld-lib.exp (run_ld_link_tests): Use check_relro_support
	to decide whether to pass extra ld option "-z norelro".

2 files changed, 23 insertions, 6 deletions

diff --git a/binutils/testsuite/config/default.exp b/binutils/testsuite/config/default.exp
index e3eae97..c02136c 100644
--- a/binutils/testsuite/config/default.exp
+++ b/binutils/testsuite/config/default.exp
@@ -34,8 +34,6 @@ if ![info exists LD] then {
 if ![info exists LDFLAGS] then {
     set LDFLAGS ""
 }
-set ld_elf_shared_opt "-z norelro"
-
 if ![info exists NM] then {
     set NM [findfile $base_dir/nm-new $base_dir/nm-new [transform nm]]
 }
diff --git a/binutils/testsuite/lib/binutils-common.exp b/binutils/testsuite/lib/binutils-common.exp
index b9e3c6d..491cd8d 100644
--- a/binutils/testsuite/lib/binutils-common.exp
+++ b/binutils/testsuite/lib/binutils-common.exp
@@ -308,6 +308,25 @@ proc check_pie_support { } {
     return $pie_available_saved
 }
 
+proc check_relro_support { } {
+    global relro_available_saved
+    global ld
+
+    if {![info exists relro_available_saved]} {
+	remote_file host delete norelro
+	set ld_output [remote_exec host $ld "-z norelro"]
+	if { [string first "not supported" $ld_output] >= 0
+	     || [string first "unrecognized option" $ld_output] >= 0
+	     || [string first "-z norelro ignored" $ld_output] >= 0
+	     || [string first "cannot find norelro" $ld_output] >= 0 } {
+	    set relro_available_saved 0
+	} else {
+	    set relro_available_saved 1
+	}
+    }
+    return $relro_available_saved
+}
+
 # Compare two files line-by-line.  FILE_1 is the actual output and FILE_2
 # is the expected output.  Ignore blank lines in either file.
 #
@@ -729,7 +748,7 @@ proc run_dump_test { name {extra_options {}} } {
     global ADDR2LINE ADDR2LINEFLAGS AS ASFLAGS ELFEDIT ELFEDITFLAGS LD LDFLAGS
     global NM NMFLAGS OBJCOPY OBJCOPYFLAGS OBJDUMP OBJDUMPFLAGS
     global READELF READELFFLAGS STRIP STRIPFLAGS
-    global copyfile env ld_elf_shared_opt runtests srcdir subdir verbose
+    global copyfile env runtests srcdir subdir verbose
 
     if [string match "*/*" $name] {
 	set file $name
@@ -1119,9 +1138,9 @@ proc run_dump_test { name {extra_options {}} } {
             set ld_extra_opt ""
             global ld
             set ld "$LD"
-            if { [is_elf_format] && [check_shared_lib_support] } {
-                set ld_extra_opt "$ld_elf_shared_opt"
-            }
+	    if [check_relro_support] {
+		set ld_extra_opt "-z norelro"
+	    }
 
             # Add -L$srcdir/$subdir so that the linker command can use
             # linker scripts in the source directory.