powerpc: suppress some linker warnings in recent linker versions

This is a follow on from commit

  0d362be5b1 ("Makefile: link with -z noexecstack --no-warn-rwx-segments")

for arch/powerpc/boot to address wanrings like:

  ld: warning: opal-calls.o: missing .note.GNU-stack section implies executable stack
  ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
  ld: warning: arch/powerpc/boot/zImage.epapr has a LOAD segment with RWX permissions

This fixes issue https://github.com/linuxppc/issues/issues/417

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221010165721.106267e6@canb.auug.org.au

arch/powerpc/boot/wrapper

@@ -215,6 +215,11 @@ ld_version()
     }'
 }
 
+ld_is_lld()
+{
+	${CROSS}ld -V 2>&1 | grep -q LLD
+}
+
 # Do not include PT_INTERP segment when linking pie. Non-pie linking
 # just ignores this option.
 LD_VERSION=$(${CROSS}ld --version | ld_version)
@@ -223,6 +228,14 @@ if [ "$LD_VERSION" -ge "$LD_NO_DL_MIN_VERSION" ] ; then
 	nodl="--no-dynamic-linker"
 fi
 
+# suppress some warnings in recent ld versions
+nowarn="-z noexecstack"
+if ! ld_is_lld; then
+	if [ "$LD_VERSION" -ge "$(echo 2.39 | ld_version)" ]; then
+		nowarn="$nowarn --no-warn-rwx-segments"
+	fi
+fi
+
 platformo=$object/"$platform".o
 lds=$object/zImage.lds
 ext=strip
@@ -504,7 +517,7 @@ if [ "$platform" != "miboot" ]; then
         text_start="-Ttext $link_address"
     fi
 #link everything
-    ${CROSS}ld -m $format -T $lds $text_start $pie $nodl $rodynamic $notext -o "$ofile" $map \
+    ${CROSS}ld -m $format -T $lds $text_start $pie $nodl $nowarn $rodynamic $notext -o "$ofile" $map \
 	$platformo $tmp $object/wrapper.a
     rm $tmp
 fi