Commit 7dd65feb authored by Albin Tonnerre's avatar Albin Tonnerre Committed by Linus Torvalds

lib: add support for LZO-compressed kernels

This patch series adds generic support for creating and extracting
LZO-compressed kernel images, as well as support for using such images on
the x86 and ARM architectures, and support for creating and using
LZO-compressed initrd and initramfs images.

Russell King said:

: Testing on a Cortex A9 model:
: - lzo decompressor is 65% of the time gzip takes to decompress a kernel
: - lzo kernel is 9% larger than a gzip kernel
:
: which I'm happy to say confirms your figures when comparing the two.
:
: However, when comparing your new gzip code to the old gzip code:
: - new is 99% of the size of the old code
: - new takes 42% of the time to decompress than the old code
:
: What this means is that for a proper comparison, the results get even better:
: - lzo is 7.5% larger than the old gzip'd kernel image
: - lzo takes 28% of the time that the old gzip code took
:
: So the expense seems definitely worth the effort.  The only reason I
: can think of ever using gzip would be if you needed the additional
: compression (eg, because you have limited flash to store the image.)
:
: I would argue that the default for ARM should therefore be LZO.

This patch:

The lzo compressor is worse than gzip at compression, but faster at
extraction.  Here are some figures for an ARM board I'm working on:

Uncompressed size: 3.24Mo
gzip  1.61Mo 0.72s
lzo   1.75Mo 0.48s

So for a compression ratio that is still relatively close to gzip, it's
much faster to extract, at least in that case.

This part contains:
 - Makefile routine to support lzo compression
 - Fixes to the existing lzo compressor so that it can be used in
   compressed kernels
 - wrapper around the existing lzo1x_decompress, as it only extracts one
   block at a time, while we need to extract a whole file here
 - config dialog for kernel compression

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: 's avatarAlbin Tonnerre <albin.tonnerre@free-electrons.com>
Tested-by: 's avatarWu Zhangjin <wuzhangjin@gmail.com>
Acked-by: 's avatar"H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Tested-by: 's avatarRussell King <rmk@arm.linux.org.uk>
Acked-by: 's avatarRussell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ac4c2a3b
#ifndef DECOMPRESS_UNLZO_H
#define DECOMPRESS_UNLZO_H
int unlzo(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
......@@ -115,10 +115,13 @@ config HAVE_KERNEL_BZIP2
config HAVE_KERNEL_LZMA
bool
config HAVE_KERNEL_LZO
bool
choice
prompt "Kernel compression mode"
default KERNEL_GZIP
depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
help
The linux kernel is a kind of self-extracting executable.
Several compression algorithms are available, which differ
......@@ -141,9 +144,8 @@ config KERNEL_GZIP
bool "Gzip"
depends on HAVE_KERNEL_GZIP
help
The old and tried gzip compression. Its compression ratio is
the poorest among the 3 choices; however its speed (both
compression and decompression) is the fastest.
The old and tried gzip compression. It provides a good balance
between compression ratio and decompression speed.
config KERNEL_BZIP2
bool "Bzip2"
......@@ -164,6 +166,14 @@ config KERNEL_LZMA
two. Compression is slowest. The kernel size is about 33%
smaller with LZMA in comparison to gzip.
config KERNEL_LZO
bool "LZO"
depends on HAVE_KERNEL_LZO
help
Its compression ratio is the poorest among the 4. The kernel
size is about about 10% bigger than gzip; however its speed
(both compression and decompression) is the fastest.
endchoice
config SWAP
......
/*
* LZO decompressor for the Linux kernel. Code borrowed from the lzo
* implementation by Markus Franz Xaver Johannes Oberhumer.
*
* Linux kernel adaptation:
* Copyright (C) 2009
* Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
*
* Original code:
* Copyright (C) 1996-2005 Markus Franz Xaver Johannes Oberhumer
* All Rights Reserved.
*
* lzop and the LZO library are free software; you can redistribute them
* and/or modify them 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 program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING.
* If not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Markus F.X.J. Oberhumer
* <markus@oberhumer.com>
* http://www.oberhumer.com/opensource/lzop/
*/
#ifdef STATIC
#include "lzo/lzo1x_decompress.c"
#else
#include <linux/slab.h>
#include <linux/decompress/unlzo.h>
#endif
#include <linux/types.h>
#include <linux/lzo.h>
#include <linux/decompress/mm.h>
#include <linux/compiler.h>
#include <asm/unaligned.h>
static const unsigned char lzop_magic[] = {
0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a };
#define LZO_BLOCK_SIZE (256*1024l)
#define HEADER_HAS_FILTER 0x00000800L
STATIC inline int INIT parse_header(u8 *input, u8 *skip)
{
int l;
u8 *parse = input;
u8 level = 0;
u16 version;
/* read magic: 9 first bits */
for (l = 0; l < 9; l++) {
if (*parse++ != lzop_magic[l])
return 0;
}
/* get version (2bytes), skip library version (2),
* 'need to be extracted' version (2) and
* method (1) */
version = get_unaligned_be16(parse);
parse += 7;
if (version >= 0x0940)
level = *parse++;
if (get_unaligned_be32(parse) & HEADER_HAS_FILTER)
parse += 8; /* flags + filter info */
else
parse += 4; /* flags */
/* skip mode and mtime_low */
parse += 8;
if (version >= 0x0940)
parse += 4; /* skip mtime_high */
l = *parse++;
/* don't care about the file name, and skip checksum */
parse += l + 4;
*skip = parse - input;
return 1;
}
STATIC inline int INIT unlzo(u8 *input, int in_len,
int (*fill) (void *, unsigned int),
int (*flush) (void *, unsigned int),
u8 *output, int *posp,
void (*error_fn) (char *x))
{
u8 skip = 0, r = 0;
u32 src_len, dst_len;
size_t tmp;
u8 *in_buf, *in_buf_save, *out_buf;
int obytes_processed = 0;
set_error_fn(error_fn);
if (output) {
out_buf = output;
} else if (!flush) {
error("NULL output pointer and no flush function provided");
goto exit;
} else {
out_buf = malloc(LZO_BLOCK_SIZE);
if (!out_buf) {
error("Could not allocate output buffer");
goto exit;
}
}
if (input && fill) {
error("Both input pointer and fill function provided, don't know what to do");
goto exit_1;
} else if (input) {
in_buf = input;
} else if (!fill || !posp) {
error("NULL input pointer and missing position pointer or fill function");
goto exit_1;
} else {
in_buf = malloc(lzo1x_worst_compress(LZO_BLOCK_SIZE));
if (!in_buf) {
error("Could not allocate input buffer");
goto exit_1;
}
}
in_buf_save = in_buf;
if (posp)
*posp = 0;
if (fill)
fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
if (!parse_header(input, &skip)) {
error("invalid header");
goto exit_2;
}
in_buf += skip;
if (posp)
*posp = skip;
for (;;) {
/* read uncompressed block size */
dst_len = get_unaligned_be32(in_buf);
in_buf += 4;
/* exit if last block */
if (dst_len == 0) {
if (posp)
*posp += 4;
break;
}
if (dst_len > LZO_BLOCK_SIZE) {
error("dest len longer than block size");
goto exit_2;
}
/* read compressed block size, and skip block checksum info */
src_len = get_unaligned_be32(in_buf);
in_buf += 8;
if (src_len <= 0 || src_len > dst_len) {
error("file corrupted");
goto exit_2;
}
/* decompress */
tmp = dst_len;
r = lzo1x_decompress_safe((u8 *) in_buf, src_len,
out_buf, &tmp);
if (r != LZO_E_OK || dst_len != tmp) {
error("Compressed data violation");
goto exit_2;
}
obytes_processed += dst_len;
if (flush)
flush(out_buf, dst_len);
if (output)
out_buf += dst_len;
if (posp)
*posp += src_len + 12;
if (fill) {
in_buf = in_buf_save;
fill(in_buf, lzo1x_worst_compress(LZO_BLOCK_SIZE));
} else
in_buf += src_len;
}
exit_2:
if (!input)
free(in_buf);
exit_1:
if (!output)
free(out_buf);
exit:
return obytes_processed;
}
#define decompress unlzo
......@@ -11,11 +11,13 @@
* Richard Purdie <rpurdie@openedhand.com>
*/
#ifndef STATIC
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/lzo.h>
#include <asm/byteorder.h>
#endif
#include <asm/unaligned.h>
#include <linux/lzo.h>
#include "lzodefs.h"
#define HAVE_IP(x, ip_end, ip) ((size_t)(ip_end - ip) < (x))
......@@ -244,9 +246,10 @@ int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
*out_len = op - out;
return LZO_E_LOOKBEHIND_OVERRUN;
}
#ifndef STATIC
EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LZO1X Decompressor");
#endif
......@@ -235,3 +235,8 @@ quiet_cmd_lzma = LZMA $@
cmd_lzma = (cat $(filter-out FORCE,$^) | \
lzma -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
(rm -f $@ ; false)
quiet_cmd_lzo = LZO $@
cmd_lzo = (cat $(filter-out FORCE,$^) | \
lzop -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
(rm -f $@ ; false)
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