[RFC PATCH 16/18] powerpc/boot: add support for 64bit big endian wrapper

[Cédric Le Goater]

The boot wrapper is now compiled using -m64 for 64bit kernels.

The linker script is generated using the kernel preprocessor flags
to make use of the CONFIG_PPC64 definitions and the wrapper script is
modified to take into account the new elf64ppc format.

zImage is compiled as a position independent executable (-pie) which
makes it loadable at any address by the firmware. This is subject to
comment as I am not sure what are the requirement for the different
boot loaders.

Signed-off-by: Cédric Le Goater <clg at fr.ibm.com>
---

There is probably a better way to compile in 64bit than what this 
patch is proposing. Suggestions ?

 arch/powerpc/boot/Makefile     |    9 ++++++++-
 arch/powerpc/boot/wrapper      |   14 +++++++++++++-
 arch/powerpc/boot/zImage.lds.S |   25 ++++++++++++++++++++++++-
 3 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index 4c4ec163a7a1..bedbd46273e4 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -24,6 +24,9 @@ BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		 -fomit-frame-pointer -fno-builtin -fPIC -nostdinc \
 		 -isystem $(shell $(CROSS32CC) -print-file-name=include) \
 		 -mbig-endian
+ifdef CONFIG_PPC64
+BOOTCFLAGS	+= -m64
+endif
 BOOTAFLAGS	:= -D__ASSEMBLY__ $(BOOTCFLAGS) -traditional -nostdinc
 
 ifdef CONFIG_DEBUG_INFO
@@ -139,7 +142,11 @@ $(addprefix $(obj)/,$(libfdt) $(libfdtheader)): $(obj)/%: $(srctree)/scripts/dtc
 $(obj)/empty.c:
 	@touch $@
 
-$(obj)/zImage.lds $(obj)/zImage.coff.lds $(obj)/zImage.ps3.lds: $(obj)/%: $(srctree)/$(src)/%.S
+$(obj)/zImage.lds: $(obj)/%: $(srctree)/$(src)/%.S
+	$(CROSS32CC) $(cpp_flags) -E -Wp,-MD,$(depfile) -P -Upowerpc \
+		-D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<
+
+$(obj)/zImage.coff.lds $(obj)/zImage.ps3.lds : $(obj)/%: $(srctree)/$(src)/%.S
 	@cp $< $@
 
 clean-files := $(zlib) $(zlibheader) $(zliblinuxheader) \
diff --git a/arch/powerpc/boot/wrapper b/arch/powerpc/boot/wrapper
index cd0101f1d457..6eca1b4ecfa4 100755
--- a/arch/powerpc/boot/wrapper
+++ b/arch/powerpc/boot/wrapper
@@ -40,6 +40,7 @@ cacheit=
 binary=
 gzip=.gz
 pie=
+format=
 
 # cross-compilation prefix
 CROSS=
@@ -136,6 +137,13 @@ if [ -z "$kernel" ]; then
     kernel=vmlinux
 fi
 
+elfformat="`${CROSS}objdump -p "$kernel" | grep 'file format' | awk '{print $4}'`"
+case "$elfformat" in
+    elf64-powerpc)	format=elf64ppc	;;
+    elf32-powerpc)	format=elf32ppc	;;
+esac
+
+
 platformo=$object/"$platform".o
 lds=$object/zImage.lds
 ext=strip
@@ -154,6 +162,10 @@ of)
 pseries)
     platformo="$object/pseries-head.o $object/of.o $object/epapr.o"
     link_address='0x4000000'
+    if [ "$format" != "elf32ppc" ]; then
+	link_address=
+	pie=-pie
+    fi
     make_space=n
     ;;
 maple)
@@ -375,7 +387,7 @@ if [ "$platform" != "miboot" ]; then
     if [ -n "$link_address" ] ; then
         text_start="-Ttext $link_address"
     fi
-    ${CROSS}ld -m elf32ppc -T $lds $text_start $pie -o "$ofile" \
+    ${CROSS}ld -m $format -T $lds $text_start $pie -o "$ofile" \
 	$platformo $tmp $object/wrapper.a
     rm $tmp
 fi
diff --git a/arch/powerpc/boot/zImage.lds.S b/arch/powerpc/boot/zImage.lds.S
index 2bd8731f1365..afecab0aff5c 100644
--- a/arch/powerpc/boot/zImage.lds.S
+++ b/arch/powerpc/boot/zImage.lds.S
@@ -1,4 +1,10 @@
+#include <asm-generic/vmlinux.lds.h>
+
+#ifdef CONFIG_PPC64
+OUTPUT_ARCH(powerpc:common64)
+#else
 OUTPUT_ARCH(powerpc:common)
+#endif
 ENTRY(_zimage_start)
 EXTERN(_zimage_start)
 SECTIONS
@@ -16,7 +22,9 @@ SECTIONS
     *(.rodata*)
     *(.data*)
     *(.sdata*)
+#ifdef CONFIG_PPC32
     *(.got2)
+#endif
   }
   .dynsym : { *(.dynsym) }
   .dynstr : { *(.dynstr) }
@@ -27,7 +35,13 @@ SECTIONS
   }
   .hash : { *(.hash) }
   .interp : { *(.interp) }
-  .rela.dyn : { *(.rela*) }
+  .rela.dyn :
+  {
+#ifdef CONFIG_PPC64
+    __rela_dyn_start = .;
+#endif
+    *(.rela*)
+  }
 
   . = ALIGN(8);
   .kernel:dtb :
@@ -53,6 +67,15 @@ SECTIONS
     _initrd_end =  .;
   }
 
+#ifdef CONFIG_PPC64
+  .got :
+  {
+    __toc_start = .;
+    *(.got)
+    *(.toc)
+  }
+#endif
+
   . = ALIGN(4096);
   .bss       :
   {
-- 
1.7.10.4