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acrn-kernel/fs/erofs/decompressor.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2019 HUAWEI, Inc.
* https://www.huawei.com/
*/
#include "compress.h"
#include <linux/module.h>
#include <linux/lz4.h>
#ifndef LZ4_DISTANCE_MAX /* history window size */
#define LZ4_DISTANCE_MAX 65535 /* set to maximum value by default */
#endif
#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
#endif
struct z_erofs_lz4_decompress_ctx {
struct z_erofs_decompress_req *rq;
/* # of encoded, decoded pages */
unsigned int inpages, outpages;
/* decoded block total length (used for in-place decompression) */
unsigned int oend;
};
int z_erofs_load_lz4_config(struct super_block *sb,
struct erofs_super_block *dsb,
struct z_erofs_lz4_cfgs *lz4, int size)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
u16 distance;
if (lz4) {
if (size < sizeof(struct z_erofs_lz4_cfgs)) {
erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
return -EINVAL;
}
distance = le16_to_cpu(lz4->max_distance);
sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
if (!sbi->lz4.max_pclusterblks) {
sbi->lz4.max_pclusterblks = 1; /* reserved case */
} else if (sbi->lz4.max_pclusterblks >
Z_EROFS_PCLUSTER_MAX_SIZE / EROFS_BLKSIZ) {
erofs_err(sb, "too large lz4 pclusterblks %u",
sbi->lz4.max_pclusterblks);
return -EINVAL;
} else if (sbi->lz4.max_pclusterblks >= 2) {
erofs_info(sb, "EXPERIMENTAL big pcluster feature in use. Use at your own risk!");
}
} else {
distance = le16_to_cpu(dsb->u1.lz4_max_distance);
sbi->lz4.max_pclusterblks = 1;
}
sbi->lz4.max_distance_pages = distance ?
DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
LZ4_MAX_DISTANCE_PAGES;
return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
}
/*
* Fill all gaps with bounce pages if it's a sparse page list. Also check if
* all physical pages are consecutive, which can be seen for moderate CR.
*/
static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
struct page **pagepool)
{
struct z_erofs_decompress_req *rq = ctx->rq;
struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
BITS_PER_LONG)] = { 0 };
unsigned int lz4_max_distance_pages =
EROFS_SB(rq->sb)->lz4.max_distance_pages;
void *kaddr = NULL;
unsigned int i, j, top;
top = 0;
for (i = j = 0; i < ctx->outpages; ++i, ++j) {
struct page *const page = rq->out[i];
struct page *victim;
if (j >= lz4_max_distance_pages)
j = 0;
/* 'valid' bounced can only be tested after a complete round */
if (test_bit(j, bounced)) {
DBG_BUGON(i < lz4_max_distance_pages);
DBG_BUGON(top >= lz4_max_distance_pages);
availables[top++] = rq->out[i - lz4_max_distance_pages];
}
if (page) {
__clear_bit(j, bounced);
if (kaddr) {
if (kaddr + PAGE_SIZE == page_address(page))
kaddr += PAGE_SIZE;
else
kaddr = NULL;
} else if (!i) {
kaddr = page_address(page);
}
continue;
}
kaddr = NULL;
__set_bit(j, bounced);
if (top) {
victim = availables[--top];
get_page(victim);
} else {
victim = erofs_allocpage(pagepool,
GFP_KERNEL | __GFP_NOFAIL);
set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
}
rq->out[i] = victim;
}
return kaddr ? 1 : 0;
}
static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
void *inpage, unsigned int *inputmargin, int *maptype,
bool may_inplace)
{
struct z_erofs_decompress_req *rq = ctx->rq;
unsigned int omargin, total, i, j;
struct page **in;
void *src, *tmp;
if (rq->inplace_io) {
omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
if (rq->partial_decoding || !may_inplace ||
omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
goto docopy;
for (i = 0; i < ctx->inpages; ++i) {
DBG_BUGON(rq->in[i] == NULL);
for (j = 0; j < ctx->outpages - ctx->inpages + i; ++j)
if (rq->out[j] == rq->in[i])
goto docopy;
}
}
if (ctx->inpages <= 1) {
*maptype = 0;
return inpage;
}
kunmap_atomic(inpage);
might_sleep();
src = erofs_vm_map_ram(rq->in, ctx->inpages);
if (!src)
return ERR_PTR(-ENOMEM);
*maptype = 1;
return src;
docopy:
/* Or copy compressed data which can be overlapped to per-CPU buffer */
in = rq->in;
src = erofs_get_pcpubuf(ctx->inpages);
if (!src) {
DBG_BUGON(1);
kunmap_atomic(inpage);
return ERR_PTR(-EFAULT);
}
tmp = src;
total = rq->inputsize;
while (total) {
unsigned int page_copycnt =
min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
if (!inpage)
inpage = kmap_atomic(*in);
memcpy(tmp, inpage + *inputmargin, page_copycnt);
kunmap_atomic(inpage);
inpage = NULL;
tmp += page_copycnt;
total -= page_copycnt;
++in;
*inputmargin = 0;
}
*maptype = 2;
return src;
}
/*
* Get the exact inputsize with zero_padding feature.
* - For LZ4, it should work if zero_padding feature is on (5.3+);
* - For MicroLZMA, it'd be enabled all the time.
*/
int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
unsigned int padbufsize)
{
const char *padend;
padend = memchr_inv(padbuf, 0, padbufsize);
if (!padend)
return -EFSCORRUPTED;
rq->inputsize -= padend - padbuf;
rq->pageofs_in += padend - padbuf;
return 0;
}
static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
u8 *out)
{
struct z_erofs_decompress_req *rq = ctx->rq;
bool support_0padding = false, may_inplace = false;
unsigned int inputmargin;
u8 *headpage, *src;
int ret, maptype;
DBG_BUGON(*rq->in == NULL);
headpage = kmap_atomic(*rq->in);
/* LZ4 decompression inplace is only safe if zero_padding is enabled */
if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
support_0padding = true;
ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
min_t(unsigned int, rq->inputsize,
EROFS_BLKSIZ - rq->pageofs_in));
if (ret) {
kunmap_atomic(headpage);
return ret;
}
may_inplace = !((rq->pageofs_in + rq->inputsize) &
(EROFS_BLKSIZ - 1));
}
inputmargin = rq->pageofs_in;
src = z_erofs_lz4_handle_overlap(ctx, headpage, &inputmargin,
&maptype, may_inplace);
if (IS_ERR(src))
return PTR_ERR(src);
/* legacy format could compress extra data in a pcluster. */
if (rq->partial_decoding || !support_0padding)
ret = LZ4_decompress_safe_partial(src + inputmargin, out,
rq->inputsize, rq->outputsize, rq->outputsize);
else
ret = LZ4_decompress_safe(src + inputmargin, out,
rq->inputsize, rq->outputsize);
if (ret != rq->outputsize) {
erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
ret, rq->inputsize, inputmargin, rq->outputsize);
print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
16, 1, src + inputmargin, rq->inputsize, true);
print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
16, 1, out, rq->outputsize, true);
if (ret >= 0)
memset(out + ret, 0, rq->outputsize - ret);
ret = -EIO;
} else {
ret = 0;
}
if (maptype == 0) {
kunmap_atomic(headpage);
} else if (maptype == 1) {
vm_unmap_ram(src, ctx->inpages);
} else if (maptype == 2) {
erofs_put_pcpubuf(src);
} else {
DBG_BUGON(1);
return -EFAULT;
}
return ret;
}
static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
struct z_erofs_lz4_decompress_ctx ctx;
unsigned int dst_maptype;
void *dst;
int ret;
ctx.rq = rq;
ctx.oend = rq->pageofs_out + rq->outputsize;
ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
/* one optimized fast path only for non bigpcluster cases yet */
if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
DBG_BUGON(!*rq->out);
dst = kmap_atomic(*rq->out);
dst_maptype = 0;
goto dstmap_out;
}
/* general decoding path which can be used for all cases */
ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
if (ret < 0) {
return ret;
} else if (ret > 0) {
dst = page_address(*rq->out);
dst_maptype = 1;
} else {
dst = erofs_vm_map_ram(rq->out, ctx.outpages);
if (!dst)
return -ENOMEM;
dst_maptype = 2;
}
dstmap_out:
ret = z_erofs_lz4_decompress_mem(&ctx, dst + rq->pageofs_out);
if (!dst_maptype)
kunmap_atomic(dst);
else if (dst_maptype == 2)
vm_unmap_ram(dst, ctx.outpages);
return ret;
}
static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
const unsigned int nrpages_out =
PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
const unsigned int righthalf = min_t(unsigned int, rq->outputsize,
PAGE_SIZE - rq->pageofs_out);
unsigned char *src, *dst;
if (nrpages_out > 2) {
DBG_BUGON(1);
return -EIO;
}
if (rq->out[0] == *rq->in) {
DBG_BUGON(nrpages_out != 1);
return 0;
}
src = kmap_atomic(*rq->in) + rq->pageofs_in;
if (rq->out[0]) {
dst = kmap_atomic(rq->out[0]);
memcpy(dst + rq->pageofs_out, src, righthalf);
kunmap_atomic(dst);
}
if (nrpages_out == 2) {
DBG_BUGON(!rq->out[1]);
if (rq->out[1] == *rq->in) {
memmove(src, src + righthalf, rq->pageofs_out);
} else {
dst = kmap_atomic(rq->out[1]);
memcpy(dst, src + righthalf, rq->pageofs_out);
kunmap_atomic(dst);
}
}
kunmap_atomic(src);
return 0;
}
static struct z_erofs_decompressor decompressors[] = {
[Z_EROFS_COMPRESSION_SHIFTED] = {
.decompress = z_erofs_shifted_transform,
.name = "shifted"
},
[Z_EROFS_COMPRESSION_LZ4] = {
.decompress = z_erofs_lz4_decompress,
.name = "lz4"
},
#ifdef CONFIG_EROFS_FS_ZIP_LZMA
[Z_EROFS_COMPRESSION_LZMA] = {
.decompress = z_erofs_lzma_decompress,
.name = "lzma"
},
#endif
};
int z_erofs_decompress(struct z_erofs_decompress_req *rq,
struct page **pagepool)
{
return decompressors[rq->alg].decompress(rq, pagepool);
}
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