5 files changed, 94 insertions, 3 deletions
diff --git a/arch/arm/boot/Makefile b/arch/arm/boot/Makefile
index 50f8d1be7fcb..a3af4dc08c3e 100644
--- a/arch/arm/boot/Makefile
+++ b/arch/arm/boot/Makefile
@@ -31,8 +31,19 @@ targets := Image zImage xipImage bootpImage uImage
 
 ifeq ($(CONFIG_XIP_KERNEL),y)
 
+cmd_deflate_xip_data = $(CONFIG_SHELL) -c \
+	'$(srctree)/$(src)/deflate_xip_data.sh $< $@ || { rm -f $@; false; }'
+
+ifeq ($(CONFIG_XIP_DEFLATED_DATA),y)
+quiet_cmd_mkxip = XIPZ    $@
+cmd_mkxip = $(cmd_objcopy) && $(cmd_deflate_xip_data)
+else
+quiet_cmd_mkxip = $(quiet_cmd_objcopy)
+cmd_mkxip = $(cmd_objcopy)
+endif
+
 $(obj)/xipImage: vmlinux FORCE
-	$(call if_changed,objcopy)
+	$(call if_changed,mkxip)
 	@$(kecho) '  Physical Address of xipImage: $(CONFIG_XIP_PHYS_ADDR)'
 
 $(obj)/Image $(obj)/zImage: FORCE
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index a5889238fc9f..45a6b9b7af2a 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -117,8 +117,11 @@ ccflags-y := -fpic -mno-single-pic-base -fno-builtin -I$(obj)
 asflags-y := -DZIMAGE
 
 # Supply kernel BSS size to the decompressor via a linker symbol.
-KBSS_SZ = $(shell $(CROSS_COMPILE)size $(obj)/../../../../vmlinux | \
-		awk 'END{print $$3}')
+KBSS_SZ = $(shell $(CROSS_COMPILE)nm $(obj)/../../../../vmlinux | \
+		perl -e 'while (<>) { \
+			$$bss_start=hex($$1) if /^([[:xdigit:]]+) B __bss_start$$/; \
+			$$bss_end=hex($$1) if /^([[:xdigit:]]+) B __bss_stop$$/; \
+		}; printf "%d\n", $$bss_end - $$bss_start;')
 LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ)
 # Supply ZRELADDR to the decompressor via a linker symbol.
 ifneq ($(CONFIG_AUTO_ZRELADDR),y)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 8a756870c238..45c8823c3750 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -143,6 +143,8 @@ start:
 		.word	_magic_start	@ absolute load/run zImage address
 		.word	_magic_end	@ zImage end address
 		.word	0x04030201	@ endianness flag
+		.word	0x45454545	@ another magic number to indicate
+		.word	_magic_table	@ additional data table
 
 		__EFI_HEADER
 1:
diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
index 7d06aa19c3e6..e6bf6774c4bb 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.S
+++ b/arch/arm/boot/compressed/vmlinux.lds.S
@@ -44,12 +44,22 @@ SECTIONS
     *(.glue_7t)
     *(.glue_7)
   }
+  .table : ALIGN(4) {
+    _table_start = .;
+    LONG(ZIMAGE_MAGIC(2))
+    LONG(ZIMAGE_MAGIC(0x5a534c4b))
+    LONG(ZIMAGE_MAGIC(__piggy_size_addr - _start))
+    LONG(ZIMAGE_MAGIC(_kernel_bss_size))
+    LONG(0)
+    _table_end = .;
+  }
   .rodata : {
     *(.rodata)
     *(.rodata.*)
   }
   .piggydata : {
     *(.piggydata)
+    __piggy_size_addr = . - 4;
   }
 
   . = ALIGN(4);
@@ -97,6 +107,7 @@ SECTIONS
   _magic_sig = ZIMAGE_MAGIC(0x016f2818);
   _magic_start = ZIMAGE_MAGIC(_start);
   _magic_end = ZIMAGE_MAGIC(_edata);
+  _magic_table = ZIMAGE_MAGIC(_table_start - _start);
 
   . = BSS_START;
   __bss_start = .;
diff --git a/arch/arm/boot/deflate_xip_data.sh b/arch/arm/boot/deflate_xip_data.sh
new file mode 100755
index 000000000000..1189598a25eb
--- /dev/null
+++ b/arch/arm/boot/deflate_xip_data.sh
@@ -0,0 +1,64 @@
+#!/bin/sh
+
+# XIP kernel .data segment compressor
+#
+# Created by:	Nicolas Pitre, August 2017
+# Copyright:	(C) 2017  Linaro Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+# This script locates the start of the .data section in xipImage and
+# substitutes it with a compressed version. The needed offsets are obtained
+# from symbol addresses in vmlinux. It is expected that .data extends to
+# the end of xipImage.
+
+set -e
+
+VMLINUX="$1"
+XIPIMAGE="$2"
+
+DD="dd status=none"
+
+# Use "make V=1" to debug this script.
+case "$KBUILD_VERBOSE" in
+*1*)
+	set -x
+	;;
+esac
+
+sym_val() {
+	# extract hex value for symbol in $1
+	local val=$($NM "$VMLINUX" | sed -n "/ $1$/{s/ .*$//p;q}")
+	[ "$val" ] || { echo "can't find $1 in $VMLINUX" 1>&2; exit 1; }
+	# convert from hex to decimal
+	echo $((0x$val))
+}
+
+__data_loc=$(sym_val __data_loc)
+_edata_loc=$(sym_val _edata_loc)
+base_offset=$(sym_val _xiprom)
+
+# convert to file based offsets
+data_start=$(($__data_loc - $base_offset))
+data_end=$(($_edata_loc - $base_offset))
+
+# Make sure data occupies the last part of the file.
+file_end=$(stat -c "%s" "$XIPIMAGE")
+if [ "$file_end" != "$data_end" ]; then
+	printf "end of xipImage doesn't match with _edata_loc (%#x vs %#x)\n" \
+	       $(($file_end + $base_offset)) $_edata_loc 2>&1
+	exit 1;
+fi
+
+# be ready to clean up
+trap 'rm -f "$XIPIMAGE.tmp"' 0 1 2 3
+
+# substitute the data section by a compressed version
+$DD if="$XIPIMAGE" count=$data_start iflag=count_bytes of="$XIPIMAGE.tmp"
+$DD if="$XIPIMAGE"  skip=$data_start iflag=skip_bytes |
+gzip -9 >> "$XIPIMAGE.tmp"
+
+# replace kernel binary
+mv -f "$XIPIMAGE.tmp" "$XIPIMAGE"