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linux/lib/842/842_compress.c

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/*
* 842 Software Compression
*
* Copyright (C) 2015 Dan Streetman, IBM Corp
*
* This program is free software; you can redistribute it and/or modify
* it 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.
*
* 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;
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;
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>");
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