ld: Add NOCF_PROTECTION_CFLAGS to turn off -fcf-protection

GCC in Ubuntu 20.04 enables -fcf-protection by default, which leads to

FAIL: S-records
FAIL: S-records with constructors
FAIL: Build plt-main with -z bndplt
FAIL: Build plt-main with PIE and -z bndplt
FAIL: Build plt-main with -z bndplt -z now
FAIL: Build plt-main with PIE and -z bndplt -z now

on x86-64.  Add NOCF_PROTECTION_CFLAGS to pass -fcf-protection=none on
these tests.

	* testsuite/config/default.exp (NOCF_PROTECTION_CFLAGS): New.
	Set to "-fcf-protection=none" if target compiler supports it.
	* testsuite/ld-srec/srec.exp: Add $NOCF_PROTECTION_CFLAGS to
	CC and CXX.
	* testsuite/ld-x86-64/x86-64.exp: Add $NOCF_PROTECTION_CFLAGS
	to PLT BND tests.

1 files changed, 38 insertions, 0 deletions

diff --git a/ld/testsuite/config/default.exp b/ld/testsuite/config/default.exp
index 7fa7911..7998f4e 100644
--- a/ld/testsuite/config/default.exp
+++ b/ld/testsuite/config/default.exp
@@ -344,6 +344,44 @@ if { ![info exists NOPIE_CFLAGS] || ![info exists NOPIE_LDFLAGS] } then {
     }
 }
 
+# Set NOCF_PROTECTION_CFLAGS to "-fcf-protection=none" if target compiler
+# supports it.
+
+if { ![info exists NOCF_PROTECTION_CFLAGS] } then {
+    if { [check_compiler_available] } {
+	# Check if gcc supports -fcf-protection=none.
+	set flags ""
+	if [board_info [target_info name] exists cflags] {
+	    append flags " [board_info [target_info name] cflags]"
+	}
+	if [board_info [target_info name] exists ldflags] {
+	    append flags " [board_info [target_info name] ldflags]"
+	}
+
+	set basename "tmpdir/nopie[pid]"
+	set src ${basename}.c
+	set output ${basename}
+	set f [open $src "w"]
+	puts $f "int main (void) { return 0; }"
+	close $f
+	if [is_remote host] {
+	    set src [remote_download host $src]
+	}
+	set nopie_available [run_host_cmd_yesno "$CC" "$flags -fcf-protection=none $src -o $output"]
+	remote_file host delete $src
+	remote_file host delete $output
+	file delete $src
+
+	if { $nopie_available == 1 } then {
+	    set NOCF_PROTECTION_CFLAGS "-fcf-protection=none"
+	} else {
+	    set NOCF_PROTECTION_CFLAGS ""
+	}
+    } else {
+	set NOCF_PROTECTION_CFLAGS ""
+    }
+}
+
 # Set GNU2_CFLAGS to "-mtls-dialect=gnu2" if target compiler supports it.
 
 if { ![info exists GNU2_CFLAGS] } then {