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Subject[PATCH 18/25] staging: erofs: introduce a customized LZ4 decompression
Date
We have to reduce the memory cost as much as possible,
so we don't want to decompress more data beyond
the output buffer size, however "LZ4_decompress_safe_partial"
doesn't guarantee to stop at the arbitary end position,
but stop just after its current LZ4 "sequence" is completed.

Link: https://groups.google.com/forum/#!topic/lz4c/_3kkz5N6n00

Therefore, I hacked the LZ4 decompression logic by hand,
probably NOT the fastest approach, and hope for better
implementation.

Signed-off-by: Miao Xie <miaoxie@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
drivers/staging/erofs/Makefile | 2 +-
drivers/staging/erofs/lz4defs.h | 227 ++++++++++++++++++++++++++++++++++
drivers/staging/erofs/unzip_lz4.c | 251 ++++++++++++++++++++++++++++++++++++++
3 files changed, 479 insertions(+), 1 deletion(-)
create mode 100644 drivers/staging/erofs/lz4defs.h
create mode 100644 drivers/staging/erofs/unzip_lz4.c

diff --git a/drivers/staging/erofs/Makefile b/drivers/staging/erofs/Makefile
index 490fa6c..e409637 100644
--- a/drivers/staging/erofs/Makefile
+++ b/drivers/staging/erofs/Makefile
@@ -9,5 +9,5 @@ obj-$(CONFIG_EROFS_FS) += erofs.o
ccflags-y += -I$(src)/include
erofs-objs := super.o inode.o data.o namei.o dir.o utils.o
erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
-erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o
+erofs-$(CONFIG_EROFS_FS_ZIP) += unzip_vle.o unzip_lz4.o

diff --git a/drivers/staging/erofs/lz4defs.h b/drivers/staging/erofs/lz4defs.h
new file mode 100644
index 0000000..00a0b58
--- /dev/null
+++ b/drivers/staging/erofs/lz4defs.h
@@ -0,0 +1,227 @@
+#ifndef __LZ4DEFS_H__
+#define __LZ4DEFS_H__
+
+/*
+ * lz4defs.h -- common and architecture specific defines for the kernel usage
+
+ * LZ4 - Fast LZ compression algorithm
+ * Copyright (C) 2011-2016, 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://www.lz4.org
+ * - LZ4 source repository : https://github.com/lz4/lz4
+ *
+ * Changed for kernel usage by:
+ * Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
+ */
+
+#include <asm/unaligned.h>
+#include <linux/string.h> /* memset, memcpy */
+
+#define FORCE_INLINE __always_inline
+
+/*-************************************
+ * Basic Types
+ **************************************/
+#include <linux/types.h>
+
+typedef uint8_t BYTE;
+typedef uint16_t U16;
+typedef uint32_t U32;
+typedef int32_t S32;
+typedef uint64_t U64;
+typedef uintptr_t uptrval;
+
+/*-************************************
+ * Architecture specifics
+ **************************************/
+#if defined(CONFIG_64BIT)
+#define LZ4_ARCH64 1
+#else
+#define LZ4_ARCH64 0
+#endif
+
+#if defined(__LITTLE_ENDIAN)
+#define LZ4_LITTLE_ENDIAN 1
+#else
+#define LZ4_LITTLE_ENDIAN 0
+#endif
+
+/*-************************************
+ * Constants
+ **************************************/
+#define MINMATCH 4
+
+#define WILDCOPYLENGTH 8
+#define LASTLITERALS 5
+#define MFLIMIT (WILDCOPYLENGTH + MINMATCH)
+
+/* Increase this value ==> compression run slower on incompressible data */
+#define LZ4_SKIPTRIGGER 6
+
+#define HASH_UNIT sizeof(size_t)
+
+#define KB (1 << 10)
+#define MB (1 << 20)
+#define GB (1U << 30)
+
+#define MAXD_LOG 16
+#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
+#define STEPSIZE sizeof(size_t)
+
+#define ML_BITS 4
+#define ML_MASK ((1U << ML_BITS) - 1)
+#define RUN_BITS (8 - ML_BITS)
+#define RUN_MASK ((1U << RUN_BITS) - 1)
+
+/*-************************************
+ * Reading and writing into memory
+ **************************************/
+static FORCE_INLINE U16 LZ4_read16(const void *ptr)
+{
+ return get_unaligned((const U16 *)ptr);
+}
+
+static FORCE_INLINE U32 LZ4_read32(const void *ptr)
+{
+ return get_unaligned((const U32 *)ptr);
+}
+
+static FORCE_INLINE size_t LZ4_read_ARCH(const void *ptr)
+{
+ return get_unaligned((const size_t *)ptr);
+}
+
+static FORCE_INLINE void LZ4_write16(void *memPtr, U16 value)
+{
+ put_unaligned(value, (U16 *)memPtr);
+}
+
+static FORCE_INLINE void LZ4_write32(void *memPtr, U32 value)
+{
+ put_unaligned(value, (U32 *)memPtr);
+}
+
+static FORCE_INLINE U16 LZ4_readLE16(const void *memPtr)
+{
+ return get_unaligned_le16(memPtr);
+}
+
+static FORCE_INLINE void LZ4_writeLE16(void *memPtr, U16 value)
+{
+ return put_unaligned_le16(value, memPtr);
+}
+
+static FORCE_INLINE void LZ4_copy8(void *dst, const void *src)
+{
+#if LZ4_ARCH64
+ U64 a = get_unaligned((const U64 *)src);
+
+ put_unaligned(a, (U64 *)dst);
+#else
+ U32 a = get_unaligned((const U32 *)src);
+ U32 b = get_unaligned((const U32 *)src + 1);
+
+ put_unaligned(a, (U32 *)dst);
+ put_unaligned(b, (U32 *)dst + 1);
+#endif
+}
+
+/*
+ * customized variant of memcpy,
+ * which can overwrite up to 7 bytes beyond dstEnd
+ */
+static FORCE_INLINE void LZ4_wildCopy(void *dstPtr,
+ const void *srcPtr, void *dstEnd)
+{
+ BYTE *d = (BYTE *)dstPtr;
+ const BYTE *s = (const BYTE *)srcPtr;
+ BYTE *const e = (BYTE *)dstEnd;
+
+ do {
+ LZ4_copy8(d, s);
+ d += 8;
+ s += 8;
+ } while (d < e);
+}
+
+static FORCE_INLINE unsigned int LZ4_NbCommonBytes(register size_t val)
+{
+#if LZ4_LITTLE_ENDIAN
+ return __ffs(val) >> 3;
+#else
+ return (BITS_PER_LONG - 1 - __fls(val)) >> 3;
+#endif
+}
+
+static FORCE_INLINE unsigned int LZ4_count(
+ const BYTE *pIn,
+ const BYTE *pMatch,
+ const BYTE *pInLimit)
+{
+ const BYTE *const pStart = pIn;
+
+ while (likely(pIn < pInLimit - (STEPSIZE - 1))) {
+ size_t const diff = LZ4_read_ARCH(pMatch) ^ LZ4_read_ARCH(pIn);
+
+ if (!diff) {
+ pIn += STEPSIZE;
+ pMatch += STEPSIZE;
+ continue;
+ }
+
+ pIn += LZ4_NbCommonBytes(diff);
+
+ return (unsigned int)(pIn - pStart);
+ }
+
+#if LZ4_ARCH64
+ if ((pIn < (pInLimit - 3))
+ && (LZ4_read32(pMatch) == LZ4_read32(pIn))) {
+ pIn += 4;
+ pMatch += 4;
+ }
+#endif
+
+ if ((pIn < (pInLimit - 1))
+ && (LZ4_read16(pMatch) == LZ4_read16(pIn))) {
+ pIn += 2;
+ pMatch += 2;
+ }
+
+ if ((pIn < pInLimit) && (*pMatch == *pIn))
+ pIn++;
+
+ return (unsigned int)(pIn - pStart);
+}
+
+typedef enum { noLimit = 0, limitedOutput = 1 } limitedOutput_directive;
+typedef enum { byPtr, byU32, byU16 } tableType_t;
+
+typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
+typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;
+
+typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
+typedef enum { full = 0, partial = 1 } earlyEnd_directive;
+
+#endif
diff --git a/drivers/staging/erofs/unzip_lz4.c b/drivers/staging/erofs/unzip_lz4.c
new file mode 100644
index 0000000..b1ea23f
--- /dev/null
+++ b/drivers/staging/erofs/unzip_lz4.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * linux/drivers/staging/erofs/unzip_lz4.c
+ *
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ *
+ * Original code taken from 'linux/lib/lz4/lz4_decompress.c'
+ */
+
+/*
+ * LZ4 - Fast LZ compression algorithm
+ * Copyright (C) 2011 - 2016, 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://www.lz4.org
+ * - LZ4 source repository : https://github.com/lz4/lz4
+ *
+ * Changed for kernel usage by:
+ * Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
+ */
+#include "internal.h"
+#include <asm/unaligned.h>
+#include "lz4defs.h"
+
+/*
+ * no public solution to solve our requirement yet.
+ * see: <required buffer size for LZ4_decompress_safe_partial>
+ * https://groups.google.com/forum/#!topic/lz4c/_3kkz5N6n00
+ */
+static FORCE_INLINE int customized_lz4_decompress_safe_partial(
+ const void * const source,
+ void * const dest,
+ int inputSize,
+ int outputSize)
+{
+ /* Local Variables */
+ const BYTE *ip = (const BYTE *) source;
+ const BYTE * const iend = ip + inputSize;
+
+ BYTE *op = (BYTE *) dest;
+ BYTE * const oend = op + outputSize;
+ BYTE *cpy;
+
+ static const unsigned int dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };
+ static const int dec64table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };
+
+ /* Empty output buffer */
+ if (unlikely(outputSize == 0))
+ return ((inputSize == 1) && (*ip == 0)) ? 0 : -1;
+
+ /* Main Loop : decode sequences */
+ while (1) {
+ size_t length;
+ const BYTE *match;
+ size_t offset;
+
+ /* get literal length */
+ unsigned int const token = *ip++;
+
+ length = token>>ML_BITS;
+
+ if (length == RUN_MASK) {
+ unsigned int s;
+
+ do {
+ s = *ip++;
+ length += s;
+ } while ((ip < iend - RUN_MASK) & (s == 255));
+
+ if (unlikely((size_t)(op + length) < (size_t)(op))) {
+ /* overflow detection */
+ goto _output_error;
+ }
+ if (unlikely((size_t)(ip + length) < (size_t)(ip))) {
+ /* overflow detection */
+ goto _output_error;
+ }
+ }
+
+ /* copy literals */
+ cpy = op + length;
+ if ((cpy > oend - WILDCOPYLENGTH) ||
+ (ip + length > iend - (2 + 1 + LASTLITERALS))) {
+ if (cpy > oend) {
+ memcpy(op, ip, length = oend - op);
+ op += length;
+ break;
+ }
+
+ if (unlikely(ip + length > iend)) {
+ /*
+ * Error :
+ * read attempt beyond
+ * end of input buffer
+ */
+ goto _output_error;
+ }
+
+ memcpy(op, ip, length);
+ ip += length;
+ op += length;
+
+ if (ip > iend - 2)
+ break;
+ /* Necessarily EOF, due to parsing restrictions */
+ /* break; */
+ } else {
+ LZ4_wildCopy(op, ip, cpy);
+ ip += length;
+ op = cpy;
+ }
+
+ /* get offset */
+ offset = LZ4_readLE16(ip);
+ ip += 2;
+ match = op - offset;
+
+ if (unlikely(match < (const BYTE *)dest)) {
+ /* Error : offset outside buffers */
+ goto _output_error;
+ }
+
+ /* get matchlength */
+ length = token & ML_MASK;
+ if (length == ML_MASK) {
+ unsigned int s;
+
+ do {
+ s = *ip++;
+
+ if (ip > iend - LASTLITERALS)
+ goto _output_error;
+
+ length += s;
+ } while (s == 255);
+
+ if (unlikely((size_t)(op + length) < (size_t)op)) {
+ /* overflow detection */
+ goto _output_error;
+ }
+ }
+
+ length += MINMATCH;
+
+ /* copy match within block */
+ cpy = op + length;
+
+ if (unlikely(cpy >= oend - WILDCOPYLENGTH)) {
+ if (cpy >= oend) {
+ while (op < oend)
+ *op++ = *match++;
+ break;
+ }
+ goto __match;
+ }
+
+ /* costs ~1%; silence an msan warning when offset == 0 */
+ LZ4_write32(op, (U32)offset);
+
+ if (unlikely(offset < 8)) {
+ const int dec64 = dec64table[offset];
+
+ op[0] = match[0];
+ op[1] = match[1];
+ op[2] = match[2];
+ op[3] = match[3];
+ match += dec32table[offset];
+ memcpy(op + 4, match, 4);
+ match -= dec64;
+ } else {
+ LZ4_copy8(op, match);
+ match += 8;
+ }
+
+ op += 8;
+
+ if (unlikely(cpy > oend - 12)) {
+ BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
+
+ if (op < oCopyLimit) {
+ LZ4_wildCopy(op, match, oCopyLimit);
+ match += oCopyLimit - op;
+ op = oCopyLimit;
+ }
+__match:
+ while (op < cpy)
+ *op++ = *match++;
+ } else {
+ LZ4_copy8(op, match);
+
+ if (length > 16)
+ LZ4_wildCopy(op + 8, match + 8, cpy);
+ }
+
+ op = cpy; /* correction */
+ }
+ DBG_BUGON((void *)ip - source > inputSize);
+ DBG_BUGON((void *)op - dest > outputSize);
+
+ /* Nb of output bytes decoded */
+ return (int) ((void *)op - dest);
+
+ /* Overflow error detected */
+_output_error:
+ return -ERANGE;
+}
+
+int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen)
+{
+ int ret = customized_lz4_decompress_safe_partial(in,
+ out, inlen, outlen);
+
+ if (ret >= 0)
+ return ret;
+
+ /*
+ * LZ4_decompress_safe will return an error code
+ * (< 0) if decompression failed
+ */
+ errln("%s, failed to decompress, in[%p, %zu] outlen[%p, %zu]",
+ __func__, in, inlen, out, outlen);
+ WARN_ON(1);
+ print_hex_dump(KERN_DEBUG, "raw data [in]: ", DUMP_PREFIX_OFFSET,
+ 16, 1, in, inlen, true);
+ print_hex_dump(KERN_DEBUG, "raw data [out]: ", DUMP_PREFIX_OFFSET,
+ 16, 1, out, outlen, true);
+ return -EIO;
+}
+
--
1.9.1
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