lib: add support for LZ4-compressed kernel

Add support for extracting LZ4-compressed kernel images, as well as
LZ4-compressed ramdisk images in the kernel boot process.

Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Yann Collet <yann.collet.73@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

10 files changed, 243 insertions, 2 deletions

diff --git a/include/linux/decompress/unlz4.h b/include/linux/decompress/unlz4.h
new file mode 100644
index 000000000000..d5b68bf3ec92
--- /dev/null
+++ b/include/linux/decompress/unlz4.h
@@ -0,0 +1,10 @@
+#ifndef DECOMPRESS_UNLZ4_H
+#define DECOMPRESS_UNLZ4_H
+
+int unlz4(unsigned char *inbuf, int len,
+        int(*fill)(void*, unsigned int),
+        int(*flush)(void*, unsigned int),
+        unsigned char *output,
+        int *pos,
+        void(*error)(char *x));
+#endif
diff --git a/init/Kconfig b/init/Kconfig
index ea1be003275a..54d3fa5ae723 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -112,10 +112,13 @@ config HAVE_KERNEL_XZ
 config HAVE_KERNEL_LZO
         bool
 
+config HAVE_KERNEL_LZ4
+        bool
+
 choice
         prompt "Kernel compression mode"
         default KERNEL_GZIP
-        depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
+        depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
         help
           The linux kernel is a kind of self-extracting executable.
           Several compression algorithms are available, which differ
@@ -182,6 +185,18 @@ config KERNEL_LZO
           size is about 10% bigger than gzip; however its speed
           (both compression and decompression) is the fastest.
 
+config KERNEL_LZ4
+        bool "LZ4"
+        depends on HAVE_KERNEL_LZ4
+        help
+          LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
+          A preliminary version of LZ4 de/compression tool is available at
+          <https://code.google.com/p/lz4/>.
+
+          Its compression ratio is worse than LZO. The size of the kernel
+          is about 8% bigger than LZO. But the decompression speed is
+          faster than LZO.
+
 endchoice
 
 config DEFAULT_HOSTNAME
diff --git a/lib/Kconfig b/lib/Kconfig
index f1ed53c3aa44..e9cdc8ffdcee 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -194,6 +194,9 @@ config LZO_COMPRESS
 config LZO_DECOMPRESS
         tristate
 
+config LZ4_DECOMPRESS
+        tristate
+
 source "lib/xz/Kconfig"
 
 #
@@ -218,6 +221,10 @@ config DECOMPRESS_LZO
         select LZO_DECOMPRESS
         tristate
 
+config DECOMPRESS_LZ4
+        select LZ4_DECOMPRESS
+        tristate
+
 #
 # Generic allocator support is selected if needed
 #
diff --git a/lib/Makefile b/lib/Makefile
index 9afb4f745e8f..326f6c7e6db1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_REED_SOLOMON) += reed_solomon/
 obj-$(CONFIG_BCH) += bch.o
 obj-$(CONFIG_LZO_COMPRESS) += lzo/
 obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
+obj-$(CONFIG_LZ4_DECOMPRESS) += lz4/
 obj-$(CONFIG_XZ_DEC) += xz/
 obj-$(CONFIG_RAID6_PQ) += raid6/
 
@@ -83,6 +84,7 @@ lib-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o
 lib-$(CONFIG_DECOMPRESS_LZMA) += decompress_unlzma.o
 lib-$(CONFIG_DECOMPRESS_XZ) += decompress_unxz.o
 lib-$(CONFIG_DECOMPRESS_LZO) += decompress_unlzo.o
+lib-$(CONFIG_DECOMPRESS_LZ4) += decompress_unlz4.o
 
 obj-$(CONFIG_TEXTSEARCH) += textsearch.o
 obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o
diff --git a/lib/decompress.c b/lib/decompress.c
index f8fdedaf7b3d..4d1cd0397aab 100644
--- a/lib/decompress.c
+++ b/lib/decompress.c
@@ -11,6 +11,7 @@
 #include <linux/decompress/unxz.h>
 #include <linux/decompress/inflate.h>
 #include <linux/decompress/unlzo.h>
+#include <linux/decompress/unlz4.h>
 
 #include <linux/types.h>
 #include <linux/string.h>
@@ -31,6 +32,9 @@
 #ifndef CONFIG_DECOMPRESS_LZO
 # define unlzo NULL
 #endif
+#ifndef CONFIG_DECOMPRESS_LZ4
+# define unlz4 NULL
+#endif
 
 struct compress_format {
         unsigned char magic[2];
@@ -45,6 +49,7 @@ static const struct compress_format compressed_formats[] __initconst = {
         { {0x5d, 0x00}, "lzma", unlzma },
         { {0xfd, 0x37}, "xz", unxz },
         { {0x89, 0x4c}, "lzo", unlzo },
+        { {0x02, 0x21}, "lz4", unlz4 },
         { {0, 0}, NULL, NULL }
 };
 
diff --git a/lib/decompress_unlz4.c b/lib/decompress_unlz4.c
new file mode 100644
index 000000000000..3e67cfad16ad
--- /dev/null
+++ b/lib/decompress_unlz4.c
@@ -0,0 +1,187 @@
+/*
+ * Wrapper for decompressing LZ4-compressed kernel, initramfs, and initrd
+ *
+ * Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>
+ *
+ * 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.
+ */
+
+#ifdef STATIC
+#define PREBOOT
+#include "lz4/lz4_decompress.c"
+#else
+#include <linux/decompress/unlz4.h>
+#endif
+#include <linux/types.h>
+#include <linux/lz4.h>
+#include <linux/decompress/mm.h>
+#include <linux/compiler.h>
+
+#include <asm/unaligned.h>
+
+/*
+ * Note: Uncompressed chunk size is used in the compressor side
+ * (userspace side for compression).
+ * It is hardcoded because there is not proper way to extract it
+ * from the binary stream which is generated by the preliminary
+ * version of LZ4 tool so far.
+ */
+#define LZ4_DEFAULT_UNCOMPRESSED_CHUNK_SIZE (8 << 20)
+#define ARCHIVE_MAGICNUMBER 0x184C2102
+
+STATIC inline int INIT unlz4(u8 *input, int in_len,
+                                int (*fill) (void *, unsigned int),
+                                int (*flush) (void *, unsigned int),
+                                u8 *output, int *posp,
+                                void (*error) (char *x))
+{
+        int ret = -1;
+        size_t chunksize = 0;
+        size_t uncomp_chunksize = LZ4_DEFAULT_UNCOMPRESSED_CHUNK_SIZE;
+        u8 *inp;
+        u8 *inp_start;
+        u8 *outp;
+        int size = in_len;
+#ifdef PREBOOT
+        size_t out_len = get_unaligned_le32(input + in_len);
+#endif
+        size_t dest_len;
+
+
+        if (output) {
+                outp = output;
+        } else if (!flush) {
+                error("NULL output pointer and no flush function provided");
+                goto exit_0;
+        } else {
+                outp = large_malloc(uncomp_chunksize);
+                if (!outp) {
+                        error("Could not allocate output buffer");
+                        goto exit_0;
+                }
+        }
+
+        if (input && fill) {
+                error("Both input pointer and fill function provided,");
+                goto exit_1;
+        } else if (input) {
+                inp = input;
+        } else if (!fill) {
+                error("NULL input pointer and missing fill function");
+                goto exit_1;
+        } else {
+                inp = large_malloc(lz4_compressbound(uncomp_chunksize));
+                if (!inp) {
+                        error("Could not allocate input buffer");
+                        goto exit_1;
+                }
+        }
+        inp_start = inp;
+
+        if (posp)
+                *posp = 0;
+
+        if (fill)
+                fill(inp, 4);
+
+        chunksize = get_unaligned_le32(inp);
+        if (chunksize == ARCHIVE_MAGICNUMBER) {
+                inp += 4;
+                size -= 4;
+        } else {
+                error("invalid header");
+                goto exit_2;
+        }
+
+        if (posp)
+                *posp += 4;
+
+        for (;;) {
+
+                if (fill)
+                        fill(inp, 4);
+
+                chunksize = get_unaligned_le32(inp);
+                if (chunksize == ARCHIVE_MAGICNUMBER) {
+                        inp += 4;
+                        size -= 4;
+                        if (posp)
+                                *posp += 4;
+                        continue;
+                }
+                inp += 4;
+                size -= 4;
+
+                if (posp)
+                        *posp += 4;
+
+                if (fill) {
+                        if (chunksize > lz4_compressbound(uncomp_chunksize)) {
+                                error("chunk length is longer than allocated");
+                                goto exit_2;
+                        }
+                        fill(inp, chunksize);
+                }
+#ifdef PREBOOT
+                if (out_len >= uncomp_chunksize) {
+                        dest_len = uncomp_chunksize;
+                        out_len -= dest_len;
+                } else
+                        dest_len = out_len;
+                ret = lz4_decompress(inp, &chunksize, outp, dest_len);
+#else
+                dest_len = uncomp_chunksize;
+                ret = lz4_decompress_unknownoutputsize(inp, chunksize, outp,
+                                &dest_len);
+#endif
+                if (ret < 0) {
+                        error("Decoding failed");
+                        goto exit_2;
+                }
+
+                if (flush && flush(outp, dest_len) != dest_len)
+                        goto exit_2;
+                if (output)
+                        outp += dest_len;
+                if (posp)
+                        *posp += chunksize;
+
+                size -= chunksize;
+
+                if (size == 0)
+                        break;
+                else if (size < 0) {
+                        error("data corrupted");
+                        goto exit_2;
+                }
+
+                inp += chunksize;
+                if (fill)
+                        inp = inp_start;
+        }
+
+        ret = 0;
+exit_2:
+        if (!input)
+                large_free(inp_start);
+exit_1:
+        if (!output)
+                large_free(outp);
+exit_0:
+        return ret;
+}
+
+#ifdef PREBOOT
+STATIC int INIT decompress(unsigned char *buf, int in_len,
+                              int(*fill)(void*, unsigned int),
+                              int(*flush)(void*, unsigned int),
+                              unsigned char *output,
+                              int *posp,
+                              void(*error)(char *x)
+        )
+{
+        return unlz4(buf, in_len - 4, fill, flush, output, posp, error);
+}
+#endif
diff --git a/lib/lz4/Makefile b/lib/lz4/Makefile
new file mode 100644
index 000000000000..7f548c6d1c5c
--- /dev/null
+++ b/lib/lz4/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_LZ4_DECOMPRESS) += lz4_decompress.o
diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index dcc89753af65..d3414eae73a1 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -1,7 +1,7 @@
 /*
  * LZ4 Decompressor for Linux kernel
  *
- * Copyright (C) 2013 LG Electronics Co., Ltd. (http://www.lge.com/)
+ * Copyright (C) 2013, LG Electronics, Kyungsik Lee <kyungsik.lee@lge.com>
  *
  * Based on LZ4 implementation by Yann Collet.
  *
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index f97869f1f09b..6031e2380638 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -311,6 +311,11 @@ cmd_lzo = (cat $(filter-out FORCE,$^) | \
         lzop -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
         (rm -f $@ ; false)
 
+quiet_cmd_lz4 = LZ4     $@
+cmd_lz4 = (cat $(filter-out FORCE,$^) | \
+        lz4c -l -c1 stdin stdout && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
+        (rm -f $@ ; false)
+
 # U-Boot mkimage
 # ---------------------------------------------------------------------------
 
diff --git a/usr/Kconfig b/usr/Kconfig
index 085872bb2bb5..642f503d3e9f 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -90,6 +90,15 @@ config RD_LZO
           Support loading of a LZO encoded initial ramdisk or cpio buffer
           If unsure, say N.
 
+config RD_LZ4
+        bool "Support initial ramdisks compressed using LZ4" if EXPERT
+        default !EXPERT
+        depends on BLK_DEV_INITRD
+        select DECOMPRESS_LZ4
+        help
+          Support loading of a LZ4 encoded initial ramdisk or cpio buffer
+          If unsure, say N.
+
 choice
         prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
         help