arm64: xcompile: Add support for A53 erratum 843419

This patch adds support to enable a linker workaround to a hardware
erratum on some early Cortex-A53 revisions. Since the linker option was
added very recently, we use xcompile to test whether the toolchain
supports it first. It is also guarded by a Kconfig since only a few
ARM64 SoCs will need this and it incurs a performance penalty.

BRANCH=none
BUG=none
TEST=Turned it on or off for Smaug and confirmed that it (dis)appeared
in verbose make output accordingly.

Change-Id: I01c9642d3cf489134645f0db6f79f1c788ddb00d
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Original-Commit-Id: 57128785760c4dfa32d6e6d764756443a9323cb7
Original-Change-Id: Ia5dd124f484e38460d75fb864304e7e8b18d16b7
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/294745
Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/11403
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
diff --git a/payloads/libpayload/bin/lpgcc b/payloads/libpayload/bin/lpgcc
index 17d8eda..8d0260b 100755
--- a/payloads/libpayload/bin/lpgcc
+++ b/payloads/libpayload/bin/lpgcc
@@ -181,6 +181,12 @@
 	    echo "Could not find head.o"
 	    exit 1
     fi
+
+    if grep -q ARM64_A53_ERRATUM_843419=y $BASE/../libpayload.config &&
+       grep -q fix-cortex-a53-843419 $BASE/../libpayload.xcompile; then
+            _LDFLAGS+=" -Wl,--fix-cortex-a53-843419"
+    fi
+
     if [ $DEBUGME -eq 1 ]; then
 	echo "$DEFAULT_CC $_LDFLAGS $HEAD_O $CMDLINE $_CFLAGS -lpayload $_LIBGCC"
     fi