From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- fs/erofs/decompressor.c | 516 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 516 insertions(+) create mode 100644 fs/erofs/decompressor.c (limited to 'fs/erofs/decompressor.c') diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c new file mode 100644 index 000000000..3c54e9596 --- /dev/null +++ b/fs/erofs/decompressor.c @@ -0,0 +1,516 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2019 HUAWEI, Inc. + * https://www.huawei.com/ + * Copyright (C) 2024 Alibaba Cloud + */ +#include "compress.h" +#include + +#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1) + +static int z_erofs_load_lz4_config(struct super_block *sb, + struct erofs_super_block *dsb, void *data, int size) +{ + struct erofs_sb_info *sbi = EROFS_SB(sb); + struct z_erofs_lz4_cfgs *lz4 = data; + 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 > + erofs_blknr(sb, Z_EROFS_PCLUSTER_MAX_SIZE)) { + erofs_err(sb, "too large lz4 pclusterblks %u", + sbi->lz4.max_pclusterblks); + return -EINVAL; + } + } else { + distance = le16_to_cpu(dsb->u1.lz4_max_distance); + if (!distance && !erofs_sb_has_lz4_0padding(sbi)) + return 0; + sbi->lz4.max_pclusterblks = 1; + sbi->available_compr_algs = 1 << Z_EROFS_COMPRESSION_LZ4; + } + + sbi->lz4.max_distance_pages = distance ? + DIV_ROUND_UP(distance, PAGE_SIZE) + 1 : + LZ4_MAX_DISTANCE_PAGES; + return z_erofs_gbuf_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_decompress_req *rq, + struct page **pagepool) +{ + 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 < rq->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 (!rq->fillgaps && 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 (!PageHighMem(page)) { + if (!i) { + kaddr = page_address(page); + continue; + } + if (kaddr && + kaddr + PAGE_SIZE == page_address(page)) { + kaddr += PAGE_SIZE; + continue; + } + } + kaddr = NULL; + continue; + } + kaddr = NULL; + __set_bit(j, bounced); + + if (top) { + victim = availables[--top]; + } else { + victim = __erofs_allocpage(pagepool, rq->gfp, true); + if (!victim) + return -ENOMEM; + set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE); + } + rq->out[i] = victim; + } + return kaddr ? 1 : 0; +} + +static void *z_erofs_lz4_handle_overlap(const struct z_erofs_decompress_req *rq, + void *inpage, void *out, unsigned int *inputmargin, + int *maptype, bool may_inplace) +{ + unsigned int oend, omargin, cnt, i; + struct page **in; + void *src; + + /* + * If in-place I/O isn't used, for example, the bounce compressed cache + * can hold data for incomplete read requests. Just map the compressed + * buffer as well and decompress directly. + */ + if (!rq->inplace_io) { + if (rq->inpages <= 1) { + *maptype = 0; + return inpage; + } + kunmap_local(inpage); + src = erofs_vm_map_ram(rq->in, rq->inpages); + if (!src) + return ERR_PTR(-ENOMEM); + *maptype = 1; + return src; + } + /* + * Then, deal with in-place I/Os. The reasons why in-place I/O is useful + * are: (1) It minimizes memory footprint during the I/O submission, + * which is useful for slow storage (including network devices and + * low-end HDDs/eMMCs) but with a lot inflight I/Os; (2) If in-place + * decompression can also be applied, it will reuse the unique buffer so + * that no extra CPU D-cache is polluted with temporary compressed data + * for extreme performance. + */ + oend = rq->pageofs_out + rq->outputsize; + omargin = PAGE_ALIGN(oend) - oend; + if (!rq->partial_decoding && may_inplace && + omargin >= LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize)) { + for (i = 0; i < rq->inpages; ++i) + if (rq->out[rq->outpages - rq->inpages + i] != + rq->in[i]) + break; + if (i >= rq->inpages) { + kunmap_local(inpage); + *maptype = 3; + return out + ((rq->outpages - rq->inpages) << PAGE_SHIFT); + } + } + /* + * If in-place decompression can't be applied, copy compressed data that + * may potentially overlap during decompression to a per-CPU buffer. + */ + src = z_erofs_get_gbuf(rq->inpages); + if (!src) { + DBG_BUGON(1); + kunmap_local(inpage); + return ERR_PTR(-EFAULT); + } + + for (i = 0, in = rq->in; i < rq->inputsize; i += cnt, ++in) { + cnt = min_t(u32, rq->inputsize - i, PAGE_SIZE - *inputmargin); + if (!inpage) + inpage = kmap_local_page(*in); + memcpy(src + i, inpage + *inputmargin, cnt); + kunmap_local(inpage); + inpage = NULL; + *inputmargin = 0; + } + *maptype = 2; + return src; +} + +/* + * Get the exact on-disk size of the compressed data: + * - For LZ4, it should apply if the zero_padding feature is on (5.3+); + * - For others, zero_padding is enabled all the time. + */ +const char *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 "compressed data start not found"; + rq->inputsize -= padend - padbuf; + rq->pageofs_in += padend - padbuf; + return NULL; +} + +static const char *__z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, + u8 *dst) +{ + bool may_inplace = false; + unsigned int inputmargin; + u8 *out, *headpage, *src; + const char *reason; + int ret, maptype; + + headpage = kmap_local_page(*rq->in); + reason = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in, + min_t(unsigned int, rq->inputsize, + rq->sb->s_blocksize - rq->pageofs_in)); + if (reason) { + kunmap_local(headpage); + return reason; + } + may_inplace = !((rq->pageofs_in + rq->inputsize) & + (rq->sb->s_blocksize - 1)); + + inputmargin = rq->pageofs_in; + src = z_erofs_lz4_handle_overlap(rq, headpage, dst, &inputmargin, + &maptype, may_inplace); + if (IS_ERR(src)) + return ERR_CAST(src); + + out = dst + rq->pageofs_out; + if (rq->partial_decoding) + 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) + reason = NULL; + else if (ret < 0) + reason = "corrupted compressed data"; + else + reason = "unexpected end of stream"; + + if (!maptype) { + kunmap_local(headpage); + } else if (maptype == 1) { + vm_unmap_ram(src, rq->inpages); + } else if (maptype == 2) { + z_erofs_put_gbuf(src); + } else if (maptype != 3) { + DBG_BUGON(1); + return ERR_PTR(-EFAULT); + } + return reason; +} + +static const char *z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, + struct page **pagepool) +{ + unsigned int dst_maptype; + const char *reason; + void *dst; + int ret; + + /* one optimized fast path only for non bigpcluster cases yet */ + if (rq->inpages == 1 && rq->outpages == 1 && !rq->inplace_io) { + DBG_BUGON(!*rq->out); + dst = kmap_local_page(*rq->out); + dst_maptype = 0; + } else { + /* general decoding path which can be used for all cases */ + ret = z_erofs_lz4_prepare_dstpages(rq, pagepool); + if (ret < 0) + return ERR_PTR(ret); + if (ret > 0) { + dst = page_address(*rq->out); + dst_maptype = 1; + } else { + dst = erofs_vm_map_ram(rq->out, rq->outpages); + if (!dst) + return ERR_PTR(-ENOMEM); + dst_maptype = 2; + } + } + reason = __z_erofs_lz4_decompress(rq, dst); + if (!dst_maptype) + kunmap_local(dst); + else if (dst_maptype == 2) + vm_unmap_ram(dst, rq->outpages); + return reason; +} + +static const char *z_erofs_transform_plain(struct z_erofs_decompress_req *rq, + struct page **pagepool) +{ + const unsigned int nrpages_in = rq->inpages, nrpages_out = rq->outpages; + const unsigned int bs = rq->sb->s_blocksize; + unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt; + u8 *kin; + + if (rq->outputsize > rq->inputsize) + return ERR_PTR(-EOPNOTSUPP); + if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) { + cur = bs - (rq->pageofs_out & (bs - 1)); + pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK; + cur = min(cur, rq->outputsize); + if (cur && rq->out[0]) { + kin = kmap_local_page(rq->in[nrpages_in - 1]); + if (rq->out[0] == rq->in[nrpages_in - 1]) + memmove(kin + rq->pageofs_out, kin + pi, cur); + else + memcpy_to_page(rq->out[0], rq->pageofs_out, + kin + pi, cur); + kunmap_local(kin); + } + rq->outputsize -= cur; + } + + for (; rq->outputsize; rq->pageofs_in = 0, cur += insz, ni++) { + insz = min(PAGE_SIZE - rq->pageofs_in, rq->outputsize); + rq->outputsize -= insz; + if (!rq->in[ni]) + continue; + kin = kmap_local_page(rq->in[ni]); + pi = 0; + do { + no = (rq->pageofs_out + cur + pi) >> PAGE_SHIFT; + po = (rq->pageofs_out + cur + pi) & ~PAGE_MASK; + DBG_BUGON(no >= nrpages_out); + cnt = min(insz - pi, PAGE_SIZE - po); + if (rq->out[no] == rq->in[ni]) + memmove(kin + po, + kin + rq->pageofs_in + pi, cnt); + else if (rq->out[no]) + memcpy_to_page(rq->out[no], po, + kin + rq->pageofs_in + pi, cnt); + pi += cnt; + } while (pi < insz); + kunmap_local(kin); + } + DBG_BUGON(ni > nrpages_in); + return NULL; +} + +const char *z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, + void **dst, void **src, struct page **pgpl) +{ + struct z_erofs_decompress_req *rq = dctx->rq; + struct page **pgo, *tmppage; + unsigned int j; + + if (!dctx->avail_out) { + if (++dctx->no >= rq->outpages || !rq->outputsize) + return "insufficient space for decompressed data"; + + if (dctx->kout) + kunmap_local(dctx->kout); + dctx->avail_out = min(rq->outputsize, PAGE_SIZE - rq->pageofs_out); + rq->outputsize -= dctx->avail_out; + pgo = &rq->out[dctx->no]; + if (!*pgo && rq->fillgaps) { /* deduped */ + *pgo = erofs_allocpage(pgpl, rq->gfp); + if (!*pgo) { + dctx->kout = NULL; + return ERR_PTR(-ENOMEM); + } + set_page_private(*pgo, Z_EROFS_SHORTLIVED_PAGE); + } + if (*pgo) { + dctx->kout = kmap_local_page(*pgo); + *dst = dctx->kout + rq->pageofs_out; + } else { + *dst = dctx->kout = NULL; + } + rq->pageofs_out = 0; + } + + if (dctx->inbuf_pos == dctx->inbuf_sz && rq->inputsize) { + if (++dctx->ni >= rq->inpages) + return "invalid compressed data"; + if (dctx->kout) /* unlike kmap(), take care of the orders */ + kunmap_local(dctx->kout); + kunmap_local(dctx->kin); + + dctx->inbuf_sz = min_t(u32, rq->inputsize, PAGE_SIZE); + rq->inputsize -= dctx->inbuf_sz; + dctx->kin = kmap_local_page(rq->in[dctx->ni]); + *src = dctx->kin; + dctx->bounced = false; + if (dctx->kout) { + j = (u8 *)*dst - dctx->kout; + dctx->kout = kmap_local_page(rq->out[dctx->no]); + *dst = dctx->kout + j; + } + dctx->inbuf_pos = 0; + } + + /* + * Handle overlapping: Use the given bounce buffer if the input data is + * under processing; Or utilize short-lived pages from the on-stack page + * pool, where pages are shared among the same request. Note that only + * a few inplace I/O pages need to be doubled. + */ + if (!dctx->bounced && rq->out[dctx->no] == rq->in[dctx->ni]) { + memcpy(dctx->bounce, *src, dctx->inbuf_sz); + *src = dctx->bounce; + dctx->bounced = true; + } + + for (j = dctx->ni + 1; j < rq->inpages; ++j) { + if (rq->out[dctx->no] != rq->in[j]) + continue; + tmppage = erofs_allocpage(pgpl, rq->gfp); + if (!tmppage) + return ERR_PTR(-ENOMEM); + set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE); + copy_highpage(tmppage, rq->in[j]); + rq->in[j] = tmppage; + } + return NULL; +} + +const struct z_erofs_decompressor *z_erofs_decomp[] = { + [Z_EROFS_COMPRESSION_SHIFTED] = &(const struct z_erofs_decompressor) { + .decompress = z_erofs_transform_plain, + .name = "shifted" + }, + [Z_EROFS_COMPRESSION_INTERLACED] = &(const struct z_erofs_decompressor) { + .decompress = z_erofs_transform_plain, + .name = "interlaced" + }, + [Z_EROFS_COMPRESSION_LZ4] = &(const struct z_erofs_decompressor) { + .config = z_erofs_load_lz4_config, + .decompress = z_erofs_lz4_decompress, + .init = z_erofs_gbuf_init, + .exit = z_erofs_gbuf_exit, + .name = "lz4" + }, +#ifdef CONFIG_EROFS_FS_ZIP_LZMA + [Z_EROFS_COMPRESSION_LZMA] = &z_erofs_lzma_decomp, +#endif +#ifdef CONFIG_EROFS_FS_ZIP_DEFLATE + [Z_EROFS_COMPRESSION_DEFLATE] = &z_erofs_deflate_decomp, +#endif +#ifdef CONFIG_EROFS_FS_ZIP_ZSTD + [Z_EROFS_COMPRESSION_ZSTD] = &z_erofs_zstd_decomp, +#endif +}; + +int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb) +{ + struct erofs_sb_info *sbi = EROFS_SB(sb); + struct erofs_buf buf = __EROFS_BUF_INITIALIZER; + unsigned long algs, alg; + erofs_off_t offset; + int size, ret = 0; + + if (!erofs_sb_has_compr_cfgs(sbi)) + return z_erofs_load_lz4_config(sb, dsb, NULL, 0); + + algs = le16_to_cpu(dsb->u1.available_compr_algs); + sbi->available_compr_algs = algs; + if (algs & ~Z_EROFS_ALL_COMPR_ALGS) { + erofs_err(sb, "unidentified algorithms %lx, please upgrade kernel", + algs & ~Z_EROFS_ALL_COMPR_ALGS); + return -EOPNOTSUPP; + } + + (void)erofs_init_metabuf(&buf, sb, false); + offset = EROFS_SUPER_OFFSET + sbi->sb_size; + for_each_set_bit(alg, &algs, Z_EROFS_COMPRESSION_MAX) { + const struct z_erofs_decompressor *dec = z_erofs_decomp[alg]; + void *data; + + data = erofs_read_metadata(sb, &buf, &offset, &size); + if (IS_ERR(data)) { + ret = PTR_ERR(data); + break; + } + + if (dec && dec->config) { + ret = dec->config(sb, dsb, data, size); + } else { + erofs_err(sb, "algorithm %ld isn't enabled on this kernel", + alg); + ret = -EOPNOTSUPP; + } + kfree(data); + if (ret) + break; + } + erofs_put_metabuf(&buf); + return ret; +} + +int __init z_erofs_init_decompressor(void) +{ + int i, err; + + for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) { + err = z_erofs_decomp[i] ? z_erofs_decomp[i]->init() : 0; + if (err) { + while (i--) + if (z_erofs_decomp[i]) + z_erofs_decomp[i]->exit(); + return err; + } + } + return 0; +} + +void z_erofs_exit_decompressor(void) +{ + int i; + + for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) + if (z_erofs_decomp[i]) + z_erofs_decomp[i]->exit(); +} -- cgit v1.3.1