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>

1 files changed, 187 insertions, 0 deletions

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