powerpc/boot: Add a global entry point for pseries

When entering the boot wrapper in little endian, we will need to fix
the endian order using a fixup trampoline like in the kernel. This
patch overrides the _zimage_start entry point for this purpose.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/boot/Makefile

@@ -99,6 +99,11 @@ src-plat-$(CONFIG_EMBEDDED6xx) += cuboot-pq2.c cuboot-mpc7448hpc2.c \
 src-plat-$(CONFIG_AMIGAONE) += cuboot-amigaone.c
 src-plat-$(CONFIG_PPC_PS3) += ps3-head.S ps3-hvcall.S ps3.c
 src-plat-$(CONFIG_EPAPR_BOOT) += epapr.c epapr-wrapper.c
+src-plat-$(CONFIG_PPC_PSERIES) += pseries-head.S
+src-plat-$(CONFIG_PPC_POWERNV) += pseries-head.S
+src-plat-$(CONFIG_PPC_IBM_CELL_BLADE) += pseries-head.S
+src-plat-$(CONFIG_PPC_CELLEB) += pseries-head.S
+src-plat-$(CONFIG_PPC_CELL_QPACE) += pseries-head.S
 
 src-wlib := $(sort $(src-wlib-y))
 src-plat := $(sort $(src-plat-y))

arch/powerpc/boot/pseries-head.S

+	.text
+
+	.globl _zimage_start
+_zimage_start:
+	b _zimage_start_lib

arch/powerpc/boot/wrapper

@@ -152,7 +152,7 @@ of)
     make_space=n
     ;;
 pseries)
-    platformo="$object/of.o $object/epapr.o"
+    platformo="$object/pseries-head.o $object/of.o $object/epapr.o"
     link_address='0x4000000'
     make_space=n
     ;;