[RFC PATCH v2 1/4] decompressor: Add LZ4 decompressor module

Kyungsik Lee
2013-02-26T06:24:50Z

This patch adds support for LZ4 decompression in the Linux Kernel.
LZ4 Decompression APIs for kernel are based on LZ4 implementation
by Yann Collet.

LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
LZ4 source repository : http://code.google.com/p/lz4/

Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>

v2:
- Clean up code
- Enable unaligned access for ARM v6 and above with
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
- Add lz4_decompress() for faster decompression with
uncompressed output size
---
include/linux/lz4.h | 48 +++++++
lib/lz4/lz4_decompress.c | 331 +++++++++++++++++++++++++++++++++++++++++++++++
lib/lz4/lz4defs.h | 93 +++++++++++++
3 files changed, 472 insertions(+)
create mode 100644 include/linux/lz4.h
create mode 100644 lib/lz4/lz4_decompress.c
create mode 100644 lib/lz4/lz4defs.h

diff --git a/include/linux/lz4.h b/include/linux/lz4.h
new file mode 100644
index 0000000..66b504c
--- /dev/null
+++ b/include/linux/lz4.h
@@ -0,0 +1,48 @@
+#ifndef __LZ4_H__
+#define __LZ4_H__
+/*
+ * LZ4 Kernel Interface
+ *
+ * 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.
+ */
+
+/*
+ * LZ4_COMPRESSBOUND()
+ * Provides the maximum size that LZ4 may output in a "worst case" scenario
+ * (input data not compressible)
+ */
+#define LZ4_COMPRESSBOUND(isize) (isize + ((isize)/255) + 16)
+
+/*
+ * lz4_decompress()
+ * src : source address of the compressed data
+ * src_len : is the input size, whcih is returned after decompress done
+ * dest : output buffer address of the decompressed data
+ * actual_dest_len: is the size of uncompressed data, supposing it's known
+ * return : Success if return 0
+ * Error if return (< 0)
+ * note : Destination buffer must be already allocated.
+ * a bit faster than lz4_decompress_unknownoutputsize()
+ */
+int lz4_decompress(const char *src, size_t *src_len, char *dest,
+ size_t actual_dest_len);
+
+/*
+ * lz4_decompress_unknownoutputsize()
+ * src : source address of the compressed data
+ * src_len : is the input size, therefore the compressed size
+ * dest : output buffer address of the decompressed data
+ * dest_len: is the max size of the destination buffer, which is
+ * returned with actual size of decompressed data after
+ * decompress done
+ * return : Success if return 0
+ * Error if return (< 0)
+ * note : Destination buffer must be already allocated.
+ */
+int lz4_decompress_unknownoutputsize(const char *src, size_t src_len,
+ char *dest, size_t *dest_len);
+#endif
diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
new file mode 100644
index 0000000..1998d7a
--- /dev/null
+++ b/lib/lz4/lz4_decompress.c
@@ -0,0 +1,331 @@
+/*
+ * LZ4 Decompressor for Linux kernel
+ *
+ * Copyright (C) 2013 LG Electronics Co., Ltd. (http://www.lge.com/)
+ *
+ * Based on LZ4 implementation by Yann Collet.
+ *
+ * LZ4 - Fast LZ compression algorithm
+ * Copyright (C) 2011-2012, Yann Collet.
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * You can contact the author at :
+ * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
+ * - LZ4 source repository : http://code.google.com/p/lz4/
+ */
+
+#ifndef STATIC
+#include <linux/module.h>
+#include <linux/kernel.h>
+#endif
+#include <linux/lz4.h>
+
+#include <asm/unaligned.h>
+
+#include "lz4defs.h"
+
+static int lz4_uncompress(const char *source, char *dest, int osize)
+{
+ const BYTE *ip = (const BYTE *) source;
+ const BYTE *ref;
+
+ BYTE *op = (BYTE *) dest;
+ BYTE * const oend = op + osize;
+ BYTE *cpy;
+
+ unsigned token;
+
+ size_t length;
+ size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
+#if LZ4_ARCH64
+ size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
+#endif
+
+ while (1) {
+
+ /* get runlength */
+ token = *ip++;
+ length = (token >> ML_BITS);
+ if (length == RUN_MASK) {
+ size_t len;
+
+ /* for (; (len = *ip++) == 255; length += 255){} */
+ len = *ip++;
+ for (; len == 255; length += 255)
+ len = *ip++;
+ length += len;
+ }
+
+ /* copy literals */
+ cpy = op + length;
+ if (unlikely(cpy > oend - COPYLENGTH)) {
+
+ /*
+ * Error: not enough place for another match
+ * (min 4) + 5 literals
+ */
+ if (cpy != oend)
+ goto _output_error;
+
+ memcpy(op, ip, length);
+ ip += length;
+ break; /* EOF */
+ }
+ LZ4_WILDCOPY(ip, op, cpy);
+ ip -= (op - cpy);
+ op = cpy;
+
+ /* get offset */
+ LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
+ ip += 2;
+
+ /* Error: offset create reference outside destination buffer */
+ if (unlikely(ref < (BYTE *const)dest))
+ goto _output_error;
+
+ /* get matchlength */
+ length = token & ML_MASK;
+ if (length == ML_MASK) {
+ for (; *ip == 255; length += 255)
+ ip++;
+ length += *ip++;
+ }
+
+ /* copy repeated sequence */
+ if (unlikely((op - ref) < STEPSIZE)) {
+#if LZ4_ARCH64
+ size_t dec64 = dec64table[op - ref];
+#else
+ const int dec64 = 0;
+#endif
+ op[0] = ref[0];
+ op[1] = ref[1];
+ op[2] = ref[2];
+ op[3] = ref[3];
+ op += 4;
+ ref += 4;
+ ref -= dec32table[op-ref];
+ PUT4(ref, op);
+ op += STEPSIZE - 4;
+ ref -= dec64;
+ } else {
+ LZ4_COPYSTEP(ref, op);
+ }
+ cpy = op + length - (STEPSIZE - 4);
+ if (cpy > oend - COPYLENGTH) {
+
+ /* Error: request to write beyond destination buffer */
+ if (cpy > oend)
+ goto _output_error;
+ LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
+ while (op < cpy)
+ *op++ = *ref++;
+ op = cpy;
+ /*
+ * Check EOF (should never happen, since last 5 bytes
+ * are supposed to be literals)
+ */
+ if (op == oend)
+ goto _output_error;
+ continue;
+ }
+ LZ4_SECURECOPY(ref, op, cpy);
+ op = cpy; /* correction */
+ }
+ /* end of decoding */
+ return (int) (((char *)ip) - source);
+
+ /* write overflow error detected */
+_output_error:
+ return (int) (-(((char *)ip) - source));
+}
+
+static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
+ int isize, size_t maxoutputsize)
+{
+ const BYTE *ip = (const BYTE *) source;
+ const BYTE *const iend = ip + isize;
+ const BYTE *ref;
+
+
+ BYTE *op = (BYTE *) dest;
+ BYTE * const oend = op + maxoutputsize;
+ BYTE *cpy;
+
+ size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
+#if LZ4_ARCH64
+ size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
+#endif
+
+ /* Main Loop */
+ while (ip < iend) {
+
+ unsigned token;
+ size_t length;
+
+ /* get runlength */
+ token = *ip++;
+ length = (token >> ML_BITS);
+ if (length == RUN_MASK) {
+ int s = 255;
+ while ((ip < iend) && (s == 255)) {
+ s = *ip++;
+ length += s;
+ }
+ }
+ /* copy literals */
+ cpy = op + length;
+ if ((cpy > oend - COPYLENGTH) ||
+ (ip + length > iend - COPYLENGTH)) {
+
+ if (cpy > oend)
+ goto _output_error;/* writes beyond buffer */
+
+ if (ip + length != iend)
+ goto _output_error;/*
+ * Error: LZ4 format requires
+ * to consume all input
+ * at this stage
+ */
+ memcpy(op, ip, length);
+ op += length;
+ break;/* Necessarily EOF, due to parsing restrictions */
+ }
+ LZ4_WILDCOPY(ip, op, cpy);
+ ip -= (op - cpy);
+ op = cpy;
+
+ /* get offset */
+ LZ4_READ_LITTLEENDIAN_16(ref, cpy, ip);
+ ip += 2;
+ if (ref < (BYTE * const)dest)
+ goto _output_error;
+ /*
+ * Error : offset creates reference
+ * outside of destination buffer
+ */
+
+ /* get matchlength */
+ length = (token & ML_MASK);
+ if (length == ML_MASK) {
+ while (ip < iend) {
+ int s = *ip++;
+ length += s;
+ if (s == 255)
+ continue;
+ break;
+ }
+ }
+
+ /* copy repeated sequence */
+ if (unlikely(op - ref < STEPSIZE)) {
+#if LZ4_ARCH64
+ size_t dec64 = dec64table[op - ref];
+#else
+ const int dec64 = 0;
+#endif
+ op[0] = ref[0];
+ op[1] = ref[1];
+ op[2] = ref[2];
+ op[3] = ref[3];
+ op += 4;
+ ref += 4;
+ ref -= dec32table[op - ref];
+ PUT4(ref, op);
+ op += STEPSIZE - 4;
+ ref -= dec64;
+ } else {
+ LZ4_COPYSTEP(ref, op);
+ }
+ cpy = op + length - (STEPSIZE-4);
+ if (cpy > oend - COPYLENGTH) {
+ if (cpy > oend)
+ goto _output_error; /* write outside of buf */
+
+ LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
+ while (op < cpy)
+ *op++ = *ref++;
+ op = cpy;
+ /*
+ * Check EOF (should never happen, since last 5 bytes
+ * are supposed to be literals)
+ */
+ if (op == oend)
+ goto _output_error;
+ continue;
+ }
+ LZ4_SECURECOPY(ref, op, cpy);
+ op = cpy; /* correction */
+ }
+ /* end of decoding */
+ return (int) (((char *)op) - dest);
+
+ /* write overflow error detected */
+_output_error:
+ return (int) (-(((char *)ip) - source));
+}
+
+int lz4_decompress(const char *src, size_t *src_len, char *dest,
+ size_t actual_dest_len)
+{
+ int ret = -1;
+ int input_len = 0;
+
+ input_len = lz4_uncompress(src, dest, actual_dest_len);
+ if (input_len < 0)
+ goto exit_0;
+ *src_len = input_len;
+
+ return 0;
+exit_0:
+ return ret;
+}
+#ifndef STATIC
+EXPORT_SYMBOL_GPL(lz4_decompress);
+#endif
+
+int lz4_decompress_unknownoutputsize(const char *src, size_t src_len,
+ char *dest, size_t *dest_len)
+{
+ int ret = -1;
+ int out_len = 0;
+
+ out_len = lz4_uncompress_unknownoutputsize(src, dest, src_len,
+ *dest_len);
+ if (out_len < 0)
+ goto exit_0;
+ *dest_len = out_len;
+
+ return 0;
+exit_0:
+ return ret;
+}
+#ifndef STATIC
+EXPORT_SYMBOL_GPL(lz4_decompress_unknownoutputsize);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LZ4 Decompressor");
+#endif
diff --git a/lib/lz4/lz4defs.h b/lib/lz4/lz4defs.h
new file mode 100644
index 0000000..fde76e6
--- /dev/null
+++ b/lib/lz4/lz4defs.h
@@ -0,0 +1,93 @@
+/*
+ * lz4defs.h -- architecture specific defines
+ *
+ * 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.
+ */
+
+/*
+ * Detects 64 bits mode
+ */
+#if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) \
+ || defined(__ppc64__) || defined(__LP64__))
+#define LZ4_ARCH64 1
+#else
+#define LZ4_ARCH64 0
+#endif
+
+/*
+ * Architecture-specific macros
+ */
+#define BYTE u8
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) || defined(CONFIG_ARM) \
+ && __LINUX_ARM_ARCH__ >= 6 \
+ && defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+typedef struct _U32_S { u32 v; } U32_S;
+typedef struct _U64_S { u64 v; } U64_S;
+
+#define A32(x) (((U32_S *)(x))->v)
+#define A64(x) (((U64_S *)(x))->v)
+
+#define PUT4(s, d) (A32(d) = A32(s))
+#define PUT8(s, d) (A64(d) = A64(s))
+#else /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
+
+#define PUT4(s, d) \
+ put_unaligned(get_unaligned((const u32 *) s), (u32 *) d)
+#define PUT8(s, d) \
+ put_unaligned(get_unaligned((const u64 *) s), (u64 *) d)
+#endif
+
+#define COPYLENGTH 8
+#define ML_BITS 4
+#define ML_MASK ((1U << ML_BITS) - 1)
+#define RUN_BITS (8 - ML_BITS)
+#define RUN_MASK ((1U << RUN_BITS) - 1)
+
+#if LZ4_ARCH64/* 64-bit */
+#define STEPSIZE 8
+
+#define LZ4_COPYSTEP(s, d) \
+ do { \
+ PUT8(s, d); \
+ d += 8; \
+ s += 8; \
+ } while (0)
+
+#define LZ4_COPYPACKET(s, d) LZ4_COPYSTEP(s, d)
+
+#define LZ4_SECURECOPY(s, d, e) \
+ do { \
+ if (d < e) { \
+ LZ4_WILDCOPY(s, d, e); \
+ } \
+ } while (0)
+
+#else /* 32-bit */
+#define STEPSIZE 4
+
+#define LZ4_COPYSTEP(s, d) \
+ do { \
+ PUT4(s, d); \
+ d += 4; \
+ s += 4; \
+ } while (0)
+
+#define LZ4_COPYPACKET(s, d) \
+ do { \
+ LZ4_COPYSTEP(s, d); \
+ LZ4_COPYSTEP(s, d); \
+ } while (0)
+
+#define LZ4_SECURECOPY LZ4_WILDCOPY
+#endif
+
+#define LZ4_READ_LITTLEENDIAN_16(d, s, p) \
+ (d = s - get_unaligned_le16(p))
+#define LZ4_WILDCOPY(s, d, e) \
+ do { \
+ LZ4_COPYPACKET(s, d); \
+ } while (d < e)
--
1.8.1.1