powerpc/boot: Add support for XZ compression

This patch adds an option to use XZ compression for the kernel image.

Currently this is only enabled for 64-bit Book3S targets, which is
roughly equivalent to the platforms that use the kernel's zImage
wrapper, and that have been tested.

The bulk of the 32-bit platforms and 64-bit BookE use uboot images,
which relies on uboot implementing XZ. In future we can enable XZ
support for those targets once someone has tested it.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/boot/Makefile

@@ -20,6 +20,7 @@
 all: $(obj)/zImage
 
 compress-$(CONFIG_KERNEL_GZIP) := CONFIG_KERNEL_GZIP
+compress-$(CONFIG_KERNEL_XZ)   := CONFIG_KERNEL_XZ
 
 BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		 -fno-strict-aliasing -Os -msoft-float -pipe \
@@ -226,6 +227,7 @@ endif
 endif
 
 compressor-$(CONFIG_KERNEL_GZIP) := gz
+compressor-$(CONFIG_KERNEL_XZ)   := xz
 
 # args (to if_changed): 1 = (this rule), 2 = platform, 3 = dts 4=dtb 5=initrd
 quiet_cmd_wrap	= WRAP    $@
@@ -433,6 +435,7 @@ clean-files += $(image-) $(initrd-) cuImage.* dtbImage.* treeImage.* \
 # clean up files cached by wrapper
 clean-kernel-base := vmlinux.strip vmlinux.bin
 clean-kernel := $(addsuffix .gz,$(clean-kernel-base))
+clean-kernel += $(addsuffix .xz,$(clean-kernel-base))
 # If not absolute clean-files are relative to $(obj).
 clean-files += $(addprefix $(objtree)/, $(clean-kernel))
 

arch/powerpc/boot/decompress.c

@@ -37,6 +37,11 @@
 #	include "decompress_inflate.c"
 #endif
 
+#ifdef CONFIG_KERNEL_XZ
+#	include "xz_config.h"
+#	include "../../../lib/decompress_unxz.c"
+#endif
+
 /* globals for tracking the state of the decompression */
 static unsigned long decompressed_bytes;
 static unsigned long limit;

arch/powerpc/boot/stdbool.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) IBM Corporation 2016.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This file is only necessary because some of the pre-boot decompressors
+ * expect stdbool.h to be available.
+ *
+ */
+
+#include "types.h"

arch/powerpc/boot/stdint.h

@@ -0,0 +1,13 @@
+/*
+ * Copyright (C) IBM Corporation 2016.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This file is only necessary because some of the pre-boot decompressors
+ * expect stdint.h to be available.
+ */
+
+#include "types.h"

arch/powerpc/boot/types.h

@@ -1,6 +1,8 @@
 #ifndef _TYPES_H_
 #define _TYPES_H_
 
+#include <stdbool.h>
+
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
 typedef unsigned char		u8;
@@ -34,4 +36,16 @@ typedef s64 int64_t;
 	(void) (&_x == &_y);	\
 	_x > _y ? _x : _y; })
 
+#define min_t(type, a, b) min(((type) a), ((type) b))
+#define max_t(type, a, b) max(((type) a), ((type) b))
+
+typedef int bool;
+
+#ifndef true
+#define true 1
+#endif
+
+#ifndef false
+#define false 0
+#endif
 #endif /* _TYPES_H_ */

arch/powerpc/boot/xz_config.h

@@ -0,0 +1,39 @@
+#ifndef __XZ_CONFIG_H__
+#define __XZ_CONFIG_H__
+
+/*
+ * most of this is copied from lib/xz/xz_private.h, we can't use their defines
+ * since the boot wrapper is not built in the same environment as the rest of
+ * the kernel.
+ */
+
+#include "types.h"
+#include "swab.h"
+
+static inline uint32_t swab32p(void *p)
+{
+	uint32_t *q = p;
+
+	return swab32(*q);
+}
+
+#ifdef __LITTLE_ENDIAN__
+#define get_le32(p) (*((uint32_t *) (p)))
+#else
+#define get_le32(p) swab32p(p)
+#endif
+
+#define memeq(a, b, size) (memcmp(a, b, size) == 0)
+#define memzero(buf, size) memset(buf, 0, size)
+
+/* prevent the inclusion of the xz-preboot MM headers */
+#define DECOMPR_MM_H
+#define memmove memmove
+#define XZ_EXTERN static
+
+/* xz.h needs to be included directly since we need enum xz_mode */
+#include "../../../include/linux/xz.h"
+
+#undef XZ_EXTERN
+
+#endif

arch/powerpc/platforms/Kconfig.cputype

@@ -74,6 +74,7 @@ config PPC_BOOK3S_64
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select ARCH_SUPPORTS_NUMA_BALANCING
 	select IRQ_WORK
+	select HAVE_KERNEL_XZ
 
 config PPC_BOOK3E_64
 	bool "Embedded processors"