> On Mar 16, 2020, at 6:50 AM, Petr Malat <oss@xxxxxxxxx> wrote: > > Add support for extracting ZSTD-compressed kernel images, as well as > ZSTD-compressed initramfs. Hi Petr, Thanks for putting up this patch! In the last month I rebased, retested, and refactored my patches [0][1], because we had a new use case for a zstd compressed initramfs. We have been using the patches I put up for quite some time internally, so we know they work well. I will re-submit my patches today, once I write all the commit summaries and a new cover letter. Thanks for the kick in the butt to resubmit it. Your patches are missing several things that I have included in my patches [0][1]: * Invocations of EXPORT_SYMBOL() and MODULE_LICENSE() in the pre-boot either emitted warnings or didn’t work in the pre-boot environment, unless that has changed. * The memcpy() inside of ZSTD_copy8() which is the core of zstd’s hot loop gets outlined in the x86 preboot environment unless you use __builtin_memcpy(). This destroys decompression speed. * unzstd() can use less memory when fill & flush are both NULL by calling ZSTD_decompressDCtx(). * ZO_z_extra_bytes needs to be bumped because zstd can overlap more than Other compressors. If it isn’t you could corrupt the kernel. I think it would be better to go with my patches. They have already been tested in production for both correctness and performance, and I have boot tested on x86, arm, and aarch64. I will make my case fully when I resubmit my patches. Thanks again for submitting this, because I have been dawdling! Nick [0] https://lore.kernel.org/patchwork/patch/839674/ [1] https://lore.kernel.org/patchwork/patch/839675/ > Signed-off-by: Petr Malat <oss@xxxxxxxxx> > --- > include/linux/decompress/unzstd.h | 12 +++ > init/Kconfig | 15 ++- > lib/Kconfig | 4 + > lib/Makefile | 1 + > lib/decompress.c | 5 + > lib/decompress_unzstd.c | 159 ++++++++++++++++++++++++++++++ > lib/zstd/decompress.c | 2 + > lib/zstd/fse_decompress.c | 4 +- > scripts/Makefile.lib | 3 + > usr/Kconfig | 24 +++++ > 10 files changed, 227 insertions(+), 2 deletions(-) > create mode 100644 include/linux/decompress/unzstd.h > create mode 100644 lib/decompress_unzstd.c > > diff --git a/include/linux/decompress/unzstd.h b/include/linux/decompress/unzstd.h > new file mode 100644 > index 000000000000..dd2c49d47456 > --- /dev/null > +++ b/include/linux/decompress/unzstd.h > @@ -0,0 +1,12 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef DECOMPRESS_UNZSTD_H > +#define DECOMPRESS_UNZSTD_H > + > +int unzstd(unsigned char *inbuf, long len, > + long (*fill)(void*, unsigned long), > + long (*flush)(void*, unsigned long), > + unsigned char *output, > + long *pos, > + void (*error)(char *x)); > +#endif > + > diff --git a/init/Kconfig b/init/Kconfig > index a34064a031a5..628eb3c290a2 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -172,13 +172,16 @@ config HAVE_KERNEL_LZO > config HAVE_KERNEL_LZ4 > bool > > +config HAVE_KERNEL_ZSTD > + bool > + > config HAVE_KERNEL_UNCOMPRESSED > 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 || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED > + depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED > help > The linux kernel is a kind of self-extracting executable. > Several compression algorithms are available, which differ > @@ -257,6 +260,16 @@ config KERNEL_LZ4 > is about 8% bigger than LZO. But the decompression speed is > faster than LZO. > > +config KERNEL_ZSTD > + bool "ZSTD" > + depends on HAVE_KERNEL_ZSTD > + help > + Its compression ratio is roughly 10% worst than xz, but the > + decompression is 10x faster. Currently, this is one of the optimal > + algorithms available in the kernel, as there isn't an algorithm, > + which would provide a better compression ratio and a shorter > + decompression time. > + > config KERNEL_UNCOMPRESSED > bool "None" > depends on HAVE_KERNEL_UNCOMPRESSED > diff --git a/lib/Kconfig b/lib/Kconfig > index 6e790dc55c5b..df301bd888d7 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -329,6 +329,10 @@ config DECOMPRESS_LZ4 > select LZ4_DECOMPRESS > tristate > > +config DECOMPRESS_ZSTD > + select ZSTD_DECOMPRESS > + tristate > + > # > # Generic allocator support is selected if needed > # > diff --git a/lib/Makefile b/lib/Makefile > index 93217d44237f..3ab9f4c31f8b 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -158,6 +158,7 @@ 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 > +lib-$(CONFIG_DECOMPRESS_ZSTD) += decompress_unzstd.o > > obj-$(CONFIG_TEXTSEARCH) += textsearch.o > obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o > diff --git a/lib/decompress.c b/lib/decompress.c > index 857ab1af1ef3..ab3fc90ffc64 100644 > --- a/lib/decompress.c > +++ b/lib/decompress.c > @@ -13,6 +13,7 @@ > #include <linux/decompress/inflate.h> > #include <linux/decompress/unlzo.h> > #include <linux/decompress/unlz4.h> > +#include <linux/decompress/unzstd.h> > > #include <linux/types.h> > #include <linux/string.h> > @@ -37,6 +38,9 @@ > #ifndef CONFIG_DECOMPRESS_LZ4 > # define unlz4 NULL > #endif > +#ifndef CONFIG_DECOMPRESS_ZSTD > +# define unzstd NULL > +#endif > > struct compress_format { > unsigned char magic[2]; > @@ -52,6 +56,7 @@ static const struct compress_format compressed_formats[] __initconst = { > { {0xfd, 0x37}, "xz", unxz }, > { {0x89, 0x4c}, "lzo", unlzo }, > { {0x02, 0x21}, "lz4", unlz4 }, > + { {0x28, 0xb5}, "zstd", unzstd }, > { {0, 0}, NULL, NULL } > }; > > diff --git a/lib/decompress_unzstd.c b/lib/decompress_unzstd.c > new file mode 100644 > index 000000000000..5af647a49885 > --- /dev/null > +++ b/lib/decompress_unzstd.c > @@ -0,0 +1,159 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Wrapper for decompressing ZSTD-compressed kernel, initramfs, and initrd > + * Based on decompress_unlz4.c > + * > + * Copyright (C) 2020, Petr Malat <oss@xxxxxxxxx> > + */ > + > +#ifdef STATIC > +#define PREBOOT > +#include "zstd/zstd_internal.h" > +#include "zstd/huf_decompress.c" > +#include "zstd/entropy_common.c" > +#include "zstd/fse_decompress.c" > +#include "zstd/zstd_common.c" > +#include "zstd/decompress.c" > +#include "xxhash.c" > +#else > +#include <linux/decompress/unzstd.h> > +#include <linux/zstd.h> > +#endif > +#include <linux/types.h> > +#include <linux/decompress/mm.h> > +#include <linux/compiler.h> > + > +STATIC inline int INIT unzstd(u8 *input, long in_len, > + long (*fill)(void *, unsigned long), > + long (*flush)(void *, unsigned long), > + u8 *output, long *posp, > + void (*error)(char *x)) > +{ > + int ret = -1, ws = 1 << ZSTD_WINDOWLOG_MAX; > + u8 *inp, *outp; > + ZSTD_DStream *zstd; > + void *workspace; > + size_t workspace_size; > + ZSTD_outBuffer out; > + ZSTD_inBuffer in; > + unsigned long out_len; > + unsigned long pos; > + > + if (output) { > + out_len = ULONG_MAX; // Caller knows data will fit > + outp = output; > + } else if (!flush) { > + error("NULL output pointer and no flush function provided"); > + goto exit_0; > + } else { > + out_len = ZSTD_DStreamOutSize(); > + outp = large_malloc(out_len); > + 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) { > + ZSTD_frameParams p; > + > + inp = input; > + if (!ZSTD_getFrameParams(&p, input, in_len)) > + ws = p.windowSize; > + } else if (!fill) { > + error("NULL input pointer and missing fill function"); > + goto exit_1; > + } else { > + in_len = ZSTD_DStreamInSize(); > + inp = large_malloc(in_len); > + if (!inp) { > + error("Could not allocate input buffer"); > + goto exit_1; > + } > + } > + > + workspace_size = ZSTD_DStreamWorkspaceBound(ws); > + workspace = large_malloc(workspace_size); > + if (!workspace) { > + error("Could not allocate workspace"); > + goto exit_2; > + } > + > + zstd = ZSTD_initDStream(ws, workspace, workspace_size); > + if (!zstd) { > + error("Could not initialize ZSTD"); > + goto exit_3; > + } > + > + in.src = inp; > + in.size = in_len; > + in.pos = 0; > + if (posp) > + *posp = 0; > + > + for (;;) { > + if (fill) { > + in.size = fill(inp, in_len); > + if (in.size == 0) > + break; > + } else if (in.size == in.pos) { > + break; > + } > +init: out.dst = outp; > + out.size = out_len; > + out.pos = 0; > + pos = in.pos; > + > + ret = ZSTD_decompressStream(zstd, &out, &in); > + if (posp) > + *posp += in.pos - pos; > + if (ZSTD_isError(ret)) { > + error("Decompression failed"); > + ret = -EIO; > + goto exit_3; > + } > + > + if (flush && out.pos) { > + if (flush(out.dst, out.pos) != out.pos) { > + ret = -EIO; > + goto exit_3; > + } > + goto init; > + } > + > + if (ret == 0) { > + ret = ZSTD_resetDStream(zstd); > + if (ZSTD_isError(ret)) { > + ret = -EIO; > + goto exit_3; > + } > + } > + if (in.pos < in.size) > + goto init_out; > + } > + > + ret = 0; > + > +exit_3: large_free(workspace); > +exit_2: if (!input) > + large_free(inp); > +exit_1: if (!output) > + large_free(outp); > +exit_0: return ret; > +} > + > +#ifdef PREBOOT > +STATIC int INIT __decompress(unsigned char *buf, long in_len, > + long (*fill)(void*, unsigned long), > + long (*flush)(void*, unsigned long), > + unsigned char *output, long out_len, > + long *posp, > + void (*error)(char *x) > + ) > +{ > + return unzstd(buf, in_len, fill, flush, output, posp, error); > +} > +#endif > diff --git a/lib/zstd/decompress.c b/lib/zstd/decompress.c > index 269ee9a796c1..6a5e1ce22719 100644 > --- a/lib/zstd/decompress.c > +++ b/lib/zstd/decompress.c > @@ -42,9 +42,11 @@ > /*-************************************* > * Macros > ***************************************/ > +#ifndef PREBOOT > #define ZSTD_isError ERR_isError /* for inlining */ > #define FSE_isError ERR_isError > #define HUF_isError ERR_isError > +#endif > > /*_******************************************************* > * Memory operations > diff --git a/lib/zstd/fse_decompress.c b/lib/zstd/fse_decompress.c > index a84300e5a013..bd4e9c891d96 100644 > --- a/lib/zstd/fse_decompress.c > +++ b/lib/zstd/fse_decompress.c > @@ -54,12 +54,13 @@ > /* ************************************************************** > * Error Management > ****************************************************************/ > -#define FSE_isError ERR_isError > #define FSE_STATIC_ASSERT(c) \ > { \ > enum { FSE_static_assert = 1 / (int)(!!(c)) }; \ > } /* use only *after* variable declarations */ > > +#ifndef PREBOOT > +#define FSE_isError ERR_isError > /* check and forward error code */ > #define CHECK_F(f) \ > { \ > @@ -67,6 +68,7 @@ > if (FSE_isError(e)) \ > return e; \ > } > +#endif > > /* ************************************************************** > * Templates > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 3fa32f83b2d7..1c2f2dc528dc 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -337,6 +337,9 @@ quiet_cmd_lz4 = LZ4 $@ > cmd_lz4 = { cat $(real-prereqs) | lz4c -l -c1 stdin stdout; \ > $(size_append); } > $@ > > +quiet_cmd_zstd = ZSTD $@ > + cmd_zstd = { cat $(real-prereqs) | zstd -19 --zstd=wlog=21; $(size_append); } > $@ > + > # U-Boot mkimage > # --------------------------------------------------------------------------- > > diff --git a/usr/Kconfig b/usr/Kconfig > index a6b68503d177..892eb15957db 100644 > --- a/usr/Kconfig > +++ b/usr/Kconfig > @@ -106,6 +106,15 @@ config RD_LZ4 > Support loading of a LZ4 encoded initial ramdisk or cpio buffer > If unsure, say N. > > +config RD_ZSTD > + bool "Support initial ramdisk/ramfs compressed using ZSTD" > + default y > + depends on BLK_DEV_INITRD > + select DECOMPRESS_ZSTD > + help > + Support loading of a ZSTD encoded initial ramdisk or cpio buffer > + If unsure, say N. > + > choice > prompt "Built-in initramfs compression mode" > depends on INITRAMFS_SOURCE!="" > @@ -214,6 +223,19 @@ config INITRAMFS_COMPRESSION_LZ4 > If you choose this, keep in mind that most distros don't provide lz4 > by default which could cause a build failure. > > +config INITRAMFS_COMPRESSION_ZSTD > + bool "ZSTD" > + depends on RD_ZSTD > + help > + Its compression ratio is roughly 10% worst than xz, but the > + decompression is 10x faster. Currently, this is one of the optimal > + algorithms available in the kernel, as there isn't an algorithm, > + which would provide a better compression ratio and a shorter > + decompression time. > + > + If you choose this, keep in mind that you may need to install the zstd > + tool to be able to compress the initram. > + > endchoice > > config INITRAMFS_COMPRESSION > @@ -226,10 +248,12 @@ config INITRAMFS_COMPRESSION > default ".xz" if INITRAMFS_COMPRESSION_XZ > default ".lzo" if INITRAMFS_COMPRESSION_LZO > default ".lz4" if INITRAMFS_COMPRESSION_LZ4 > + default ".zst" if INITRAMFS_COMPRESSION_ZSTD > default ".gz" if RD_GZIP > default ".lz4" if RD_LZ4 > default ".lzo" if RD_LZO > default ".xz" if RD_XZ > default ".lzma" if RD_LZMA > default ".bz2" if RD_BZIP2 > + default ".zst" if RD_ZSTD > default "" > -- > 2.20.1 >
