// SPDX-License-Identifier: GPL-2.0-or-later /* * 842 Software Compression * * Copyright (C) 2015 Dan Streetman, IBM Corp * * See 842.h for details of the 842 compressed format. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #define MODULE_NAME "842_compress" #include <linux/hashtable.h> #include "842.h" #include "842_debugfs.h" #define SW842_HASHTABLE8_BITS (10) #define SW842_HASHTABLE4_BITS (11) #define SW842_HASHTABLE2_BITS (10) /* By default, we allow compressing input buffers of any length, but we must * use the non-standard "short data" template so the decompressor can correctly * reproduce the uncompressed data buffer at the right length. However the * hardware 842 compressor will not recognize the "short data" template, and * will fail to decompress any compressed buffer containing it (I have no idea * why anyone would want to use software to compress and hardware to decompress * but that's beside the point). This parameter forces the compression * function to simply reject any input buffer that isn't a multiple of 8 bytes * long, instead of using the "short data" template, so that all compressed * buffers produced by this function will be decompressable by the 842 hardware * decompressor. Unless you have a specific need for that, leave this disabled * so that any length buffer can be compressed. */ static bool sw842_strict; module_param_named(strict, sw842_strict, bool, 0644); static u8 comp_ops[OPS_MAX][5] = { /* params size in bits */ { I8, N0, N0, N0, 0x19 }, /* 8 */ { I4, I4, N0, N0, 0x18 }, /* 18 */ { I4, I2, I2, N0, 0x17 }, /* 25 */ { I2, I2, I4, N0, 0x13 }, /* 25 */ { I2, I2, I2, I2, 0x12 }, /* 32 */ { I4, I2, D2, N0, 0x16 }, /* 33 */ { I4, D2, I2, N0, 0x15 }, /* 33 */ { I2, D2, I4, N0, 0x0e }, /* 33 */ { D2, I2, I4, N0, 0x09 }, /* 33 */ { I2, I2, I2, D2, 0x11 }, /* 40 */ { I2, I2, D2, I2, 0x10 }, /* 40 */ { I2, D2, I2, I2, 0x0d }, /* 40 */ { D2, I2, I2, I2, 0x08 }, /* 40 */ { I4, D4, N0, N0, 0x14 }, /* 41 */ { D4, I4, N0, N0, 0x04 }, /* 41 */ { I2, I2, D4, N0, 0x0f }, /* 48 */ { I2, D2, I2, D2, 0x0c }, /* 48 */ { I2, D4, I2, N0, 0x0b }, /* 48 */ { D2, I2, I2, D2, 0x07 }, /* 48 */ { D2, I2, D2, I2, 0x06 }, /* 48 */ { D4, I2, I2, N0, 0x03 }, /* 48 */ { I2, D2, D4, N0, 0x0a }, /* 56 */ { D2, I2, D4, N0, 0x05 }, /* 56 */ { D4, I2, D2, N0, 0x02 }, /* 56 */ { D4, D2, I2, N0, 0x01 }, /* 56 */ { D8, N0, N0, N0, 0x00 }, /* 64 */ }; struct sw842_hlist_node8 { struct hlist_node node; u64 data; u8 index; }; struct sw842_hlist_node4 { struct hlist_node node; u32 data; u16 index; }; struct sw842_hlist_node2 { struct hlist_node node; u16 data; u8 index; }; #define INDEX_NOT_FOUND (-1) #define INDEX_NOT_CHECKED (-2) struct sw842_param { u8 *in; u8 *instart; u64 ilen; u8 *out; u64 olen; u8 bit; u64 data8[1]; u32 data4[2]; u16 data2[4]; int index8[1]; int index4[2]; int index2[4]; DECLARE_HASHTABLE(htable8, SW842_HASHTABLE8_BITS); DECLARE_HASHTABLE(htable4, SW842_HASHTABLE4_BITS); DECLARE_HASHTABLE(htable2, SW842_HASHTABLE2_BITS); struct sw842_hlist_node8 node8[1 << I8_BITS]; struct sw842_hlist_node4 node4[1 << I4_BITS]; struct sw842_hlist_node2 node2[1 << I2_BITS]; }; #define get_input_data(p, o, b) \ be##b##_to_cpu(get_unaligned((__be##b *)((p)->in + (o)))) #define init_hashtable_nodes(p, b) do { \ int _i; \ hash_init((p)->htable##b); \ for (_i = 0; _i < ARRAY_SIZE((p)->node##b); _i++) { \ (p)->node##b[_i].index = _i; \ (p)->node##b[_i].data = 0; \ INIT_HLIST_NODE(&(p)->node##b[_i].node); \ } \ } while (0) #define find_index(p, b, n) ({ \ struct sw842_hlist_node##b *_n; \ p->index##b[n] = INDEX_NOT_FOUND; \ hash_for_each_possible(p->htable##b, _n, node, p->data##b[n]) { \ if (p->data##b[n] == _n->data) { \ p->index##b[n] = _n->index; \ break; \ } \ } \ p->index##b[n] >= 0; \ }) #define check_index(p, b, n) \ ((p)->index##b[n] == INDEX_NOT_CHECKED \ ? find_index(p, b, n) \ : (p)->index##b[n] >= 0) #define replace_hash(p, b, i, d) do { \ struct sw842_hlist_node##b *_n = &(p)->node##b[(i)+(d)]; \ hash_del(&_n->node); \ _n->data = (p)->data##b[d]; \ pr_debug("add hash index%x %x pos %x data %lx\n", b, \ (unsigned int)_n->index, \ (unsigned int)((p)->in - (p)->instart), \ (unsigned long)_n->data); \ hash_add((p)->htable##b, &_n->node, _n->data); \ } while (0) static u8 bmask[8] = { 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe }; static int add_bits(struct sw842_param *p, u64 d, u8 n); static int __split_add_bits(struct sw842_param *p, u64 d, u8 n, u8 s) { int ret; if (n <= s) return -EINVAL; ret = add_bits(p, d >> s, n - s); if (ret) return ret; return add_bits(p, d & GENMASK_ULL(s - 1, 0), s); } static int add_bits(struct sw842_param *p, u64 d, u8 n) { int b = p->bit, bits = b + n, s = round_up(bits, 8) - bits; u64 o; u8 *out = p->out; pr_debug("add %u bits %lx\n", (unsigned char)n, (unsigned long)d); if (n > 64) return -EINVAL; /* split this up if writing to > 8 bytes (i.e. n == 64 && p->bit > 0), * or if we're at the end of the output buffer and would write past end */ if (bits > 64) return __split_add_bits(p, d, n, 32); else if (p->olen < 8 && bits > 32 && bits <= 56) return __split_add_bits(p, d, n, 16); else if (p->olen < 4 && bits > 16 && bits <= 24) return __split_add_bits(p, d, n, 8); if (DIV_ROUND_UP(bits, 8) > p->olen) return -ENOSPC; o = *out & bmask[b]; d <<= s; if (bits <= 8) *out = o | d; else if (bits <= 16) put_unaligned(cpu_to_be16(o << 8 | d), (__be16 *)out); else if (bits <= 24) put_unaligned(cpu_to_be32(o << 24 | d << 8), (__be32 *)out); else if (bits <= 32) put_unaligned(cpu_to_be32(o << 24 | d), (__be32 *)out); else if (bits <= 40) put_unaligned(cpu_to_be64(o << 56 | d << 24), (__be64 *)out); else if (bits <= 48) put_unaligned(cpu_to_be64(o << 56 | d << 16), (__be64 *)out); else if (bits <= 56) put_unaligned(cpu_to_be64(o << 56 | d << 8), (__be64 *)out); else put_unaligned(cpu_to_be64(o << 56 | d), (__be64 *)out); p->bit += n; if (p->bit > 7) { p->out += p->bit / 8; p->olen -= p->bit / 8; p->bit %= 8; } return 0; } static int add_template(struct sw842_param *p, u8 c) { int ret, i, b = 0; u8 *t = comp_ops[c]; bool inv = false; if (c >= OPS_MAX) return -EINVAL; pr_debug("template %x\n", t[4]); ret = add_bits(p, t[4], OP_BITS); if (ret) return ret; for (i = 0; i < 4; i++) { pr_debug("op %x\n", t[i]); switch (t[i] & OP_AMOUNT) { case OP_AMOUNT_8: if (b) inv = true; else if (t[i] & OP_ACTION_INDEX) ret = add_bits(p, p->index8[0], I8_BITS); else if (t[i] & OP_ACTION_DATA) ret = add_bits(p, p->data8[0], 64); else inv = true; break; case OP_AMOUNT_4: if (b == 2 && t[i] & OP_ACTION_DATA) ret = add_bits(p, get_input_data(p, 2, 32), 32); else if (b != 0 && b != 4) inv = true; else if (t[i] & OP_ACTION_INDEX) ret = add_bits(p, p->index4[b >> 2], I4_BITS); else if (t[i] & OP_ACTION_DATA) ret = add_bits(p, p->data4[b >> 2], 32); else inv = true; break; case OP_AMOUNT_2: if (b != 0 && b != 2 && b != 4 && b != 6) inv = true; if (t[i] & OP_ACTION_INDEX) ret = add_bits(p, p->index2[b >> 1], I2_BITS); else if (t[i] & OP_ACTION_DATA) ret = add_bits(p, p->data2[b >> 1], 16); else inv = true; break; case OP_AMOUNT_0: inv = (b != 8) || !(t[i] & OP_ACTION_NOOP); break; default: inv = true; break; } if (ret) return ret; if (inv) { pr_err("Invalid templ %x op %d : %x %x %x %x\n", c, i, t[0], t[1], t[2], t[3]); return -EINVAL; } b += t[i] & OP_AMOUNT; } if (b != 8) { pr_err("Invalid template %x len %x : %x %x %x %x\n", c, b, t[0], t[1], t[2], t[3]); return -EINVAL; } if (sw842_template_counts) atomic_inc(&template_count[t[4]]); return 0; } static int add_repeat_template(struct sw842_param *p, u8 r) { int ret; /* repeat param is 0-based */ if (!r || --r > REPEAT_BITS_MAX) return -EINVAL; ret = add_bits(p, OP_REPEAT, OP_BITS); if (ret) return ret; ret = add_bits(p, r, REPEAT_BITS); if (ret) return ret; if (sw842_template_counts) atomic_inc(&template_repeat_count); return 0; } static int add_short_data_template(struct sw842_param *p, u8 b) { int ret, i; if (!b || b > SHORT_DATA_BITS_MAX) return -EINVAL; ret = add_bits(p, OP_SHORT_DATA, OP_BITS); if (ret) return ret; ret = add_bits(p, b, SHORT_DATA_BITS); if (ret) return ret; for (i = 0; i < b; i++) { ret = add_bits(p, p->in[i], 8); if (ret) return ret; } if (sw842_template_counts) atomic_inc(&template_short_data_count); return 0; } static int add_zeros_template(struct sw842_param *p) { int ret = add_bits(p, OP_ZEROS, OP_BITS); if (ret) return ret; if (sw842_template_counts) atomic_inc(&template_zeros_count); return 0; } static int add_end_template(struct sw842_param *p) { int ret = add_bits(p, OP_END, OP_BITS); if (ret) return ret; if (sw842_template_counts) atomic_inc(&template_end_count); return 0; } static bool check_template(struct sw842_param *p, u8 c) { u8 *t = comp_ops[c]; int i, match, b = 0; if (c >= OPS_MAX) return false; for (i = 0; i < 4; i++) { if (t[i] & OP_ACTION_INDEX) { if (t[i] & OP_AMOUNT_2) match = check_index(p, 2, b >> 1); else if (t[i] & OP_AMOUNT_4) match = check_index(p, 4, b >> 2); else if (t[i] & OP_AMOUNT_8) match = check_index(p, 8, 0); else return false; if (!match) return false; } b += t[i] & OP_AMOUNT; } return true; } static void get_next_data(struct sw842_param *p) { p->data8[0] = get_input_data(p, 0, 64); p->data4[0] = get_input_data(p, 0, 32); p->data4[1] = get_input_data(p, 4, 32); p->data2[0] = get_input_data(p, 0, 16); p->data2[1] = get_input_data(p, 2, 16); p->data2[2] = get_input_data(p, 4, 16); p->data2[3] = get_input_data(p, 6, 16); } /* update the hashtable entries. * only call this after finding/adding the current template * the dataN fields for the current 8 byte block must be already updated */ static void update_hashtables(struct sw842_param *p) { u64 pos = p->in - p->instart; u64 n8 = (pos >> 3) % (1 << I8_BITS); u64 n4 = (pos >> 2) % (1 << I4_BITS); u64 n2 = (pos >> 1) % (1 << I2_BITS); replace_hash(p, 8, n8, 0); replace_hash(p, 4, n4, 0); replace_hash(p, 4, n4, 1); replace_hash(p, 2, n2, 0); replace_hash(p, 2, n2, 1); replace_hash(p, 2, n2, 2); replace_hash(p, 2, n2, 3); } /* find the next template to use, and add it * the p->dataN fields must already be set for the current 8 byte block */ static int process_next(struct sw842_param *p) { int ret, i; p->index8[0] = INDEX_NOT_CHECKED; p->index4[0] = INDEX_NOT_CHECKED; p->index4[1] = INDEX_NOT_CHECKED; p->index2[0] = INDEX_NOT_CHECKED; p->index2[1] = INDEX_NOT_CHECKED; p->index2[2] = INDEX_NOT_CHECKED; p->index2[3] = INDEX_NOT_CHECKED; /* check up to OPS_MAX - 1; last op is our fallback */ for (i = 0; i < OPS_MAX - 1; i++) { if (check_template(p, i)) break; } ret = add_template(p, i); if (ret) return ret; return 0; } /** * sw842_compress * * Compress the uncompressed buffer of length @ilen at @in to the output buffer * @out, using no more than @olen bytes, using the 842 compression format. * * Returns: 0 on success, error on failure. The @olen parameter * will contain the number of output bytes written on success, or * 0 on error. */ int sw842_compress(const u8 *in, unsigned int ilen, u8 *out, unsigned int *olen, void *wmem) { struct sw842_param *p = (struct sw842_param *)wmem; int ret; u64 last, next, pad, total; u8 repeat_count = 0; u32 crc; BUILD_BUG_ON(sizeof(*p) > SW842_MEM_COMPRESS); init_hashtable_nodes(p, 8); init_hashtable_nodes(p, 4); init_hashtable_nodes(p, 2); p->in = (u8 *)in; p->instart = p->in; p->ilen = ilen; p->out = out; p->olen = *olen; p->bit = 0; total = p->olen; *olen = 0; /* if using strict mode, we can only compress a multiple of 8 */ if (sw842_strict && (ilen % 8)) { pr_err("Using strict mode, can't compress len %d\n", ilen); return -EINVAL; } /* let's compress at least 8 bytes, mkay? */ if (unlikely(ilen < 8)) goto skip_comp; /* make initial 'last' different so we don't match the first time */ last = ~get_unaligned((u64 *)p->in); while (p->ilen > 7) { next = get_unaligned((u64 *)p->in); /* must get the next data, as we need to update the hashtable * entries with the new data every time */ get_next_data(p); /* we don't care about endianness in last or next; * we're just comparing 8 bytes to another 8 bytes, * they're both the same endianness */ if (next == last) { /* repeat count bits are 0-based, so we stop at +1 */ if (++repeat_count <= REPEAT_BITS_MAX) goto repeat; } if (repeat_count) { ret = add_repeat_template(p, repeat_count); repeat_count = 0; if (next == last) /* reached max repeat bits */ goto repeat; } if (next == 0) ret = add_zeros_template(p); else ret = process_next(p); if (ret) return ret; repeat: last = next; update_hashtables(p); p->in += 8; p->ilen -= 8; } if (repeat_count) { ret = add_repeat_template(p, repeat_count); if (ret) return ret; } skip_comp: if (p->ilen > 0) { ret = add_short_data_template(p, p->ilen); if (ret) return ret; p->in += p->ilen; p->ilen = 0; } ret = add_end_template(p); if (ret) return ret; /* * crc(0:31) is appended to target data starting with the next * bit after End of stream template. * nx842 calculates CRC for data in big-endian format. So doing * same here so that sw842 decompression can be used for both * compressed data. */ crc = crc32_be(0, in, ilen); ret = add_bits(p, crc, CRC_BITS); if (ret) return ret; if (p->bit) { p->out++; p->olen--; p->bit = 0; } /* pad compressed length to multiple of 8 */ pad = (8 - ((total - p->olen) % 8)) % 8; if (pad) { if (pad > p->olen) /* we were so close! */ return -ENOSPC; memset(p->out, 0, pad); p->out += pad; p->olen -= pad; } if (unlikely((total - p->olen) > UINT_MAX)) return -ENOSPC; *olen = total - p->olen; return 0; } EXPORT_SYMBOL_GPL(sw842_compress); static int __init sw842_init(void) { if (sw842_template_counts) sw842_debugfs_create(); return 0; } module_init(sw842_init); static void __exit sw842_exit(void) { if (sw842_template_counts) sw842_debugfs_remove(); } module_exit(sw842_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Software 842 Compressor"); MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");