lib: add software 842 compression/decompression

S:	Supported

F:	drivers/crypto/nx/nx-842.c

F:	include/linux/nx842.h

F:	include/linux/sw842.h

F:	lib/842/

IBM Power Linux RAID adapter

M:	Brian King <brking@us.ibm.com>

#ifndef __SW842_H__

#define __SW842_H__

#define SW842_MEM_COMPRESS	(0xf000)

int sw842_compress(const u8 *src, unsigned int srclen,

		   u8 *dst, unsigned int *destlen, void *wmem);

int sw842_decompress(const u8 *src, unsigned int srclen,

		     u8 *dst, unsigned int *destlen);

#endif

#ifndef __842_H__

#define __842_H__

/* The 842 compressed format is made up of multiple blocks, each of

 * which have the format:

 *

 * <template>[arg1][arg2][arg3][arg4]

 *

 * where there are between 0 and 4 template args, depending on the specific

 * template operation.  For normal operations, each arg is either a specific

 * number of data bytes to add to the output buffer, or an index pointing

 * to a previously-written number of data bytes to copy to the output buffer.

 *

 * The template code is a 5-bit value.  This code indicates what to do with

 * the following data.  Template codes from 0 to 0x19 should use the template

 * table, the static "decomp_ops" table used in decompress.  For each template

 * (table row), there are between 1 and 4 actions; each action corresponds to

 * an arg following the template code bits.  Each action is either a "data"

 * type action, or a "index" type action, and each action results in 2, 4, or 8

 * bytes being written to the output buffer.  Each template (i.e. all actions

 * in the table row) will add up to 8 bytes being written to the output buffer.

 * Any row with less than 4 actions is padded with noop actions, indicated by

 * N0 (for which there is no corresponding arg in the compressed data buffer).

 *

 * "Data" actions, indicated in the table by D2, D4, and D8, mean that the

 * corresponding arg is 2, 4, or 8 bytes, respectively, in the compressed data

 * buffer should be copied directly to the output buffer.

 *

 * "Index" actions, indicated in the table by I2, I4, and I8, mean the

 * corresponding arg is an index parameter that points to, respectively, a 2,

 * 4, or 8 byte value already in the output buffer, that should be copied to

 * the end of the output buffer.  Essentially, the index points to a position

 * in a ring buffer that contains the last N bytes of output buffer data.

 * The number of bits for each index's arg are: 8 bits for I2, 9 bits for I4,

 * and 8 bits for I8.  Since each index points to a 2, 4, or 8 byte section,

 * this means that I2 can reference 512 bytes ((2^8 bits = 256) * 2 bytes), I4

 * can reference 2048 bytes ((2^9 = 512) * 4 bytes), and I8 can reference 2048

 * bytes ((2^8 = 256) * 8 bytes).  Think of it as a kind-of ring buffer for

 * each of I2, I4, and I8 that are updated for each byte written to the output

 * buffer.  In this implementation, the output buffer is directly used for each

 * index; there is no additional memory required.  Note that the index is into

 * a ring buffer, not a sliding window; for example, if there have been 260

 * bytes written to the output buffer, an I2 index of 0 would index to byte 256

 * in the output buffer, while an I2 index of 16 would index to byte 16 in the

 * output buffer.

 *

 * There are also 3 special template codes; 0x1b for "repeat", 0x1c for

 * "zeros", and 0x1e for "end".  The "repeat" operation is followed by a 6 bit

 * arg N indicating how many times to repeat.  The last 8 bytes written to the

 * output buffer are written again to the output buffer, N + 1 times.  The

 * "zeros" operation, which has no arg bits, writes 8 zeros to the output

 * buffer.  The "end" operation, which also has no arg bits, signals the end

 * of the compressed data.  There may be some number of padding (don't care,

 * but usually 0) bits after the "end" operation bits, to fill the buffer

 * length to a specific byte multiple (usually a multiple of 8, 16, or 32

 * bytes).

 *

 * This software implementation also uses one of the undefined template values,

 * 0x1d as a special "short data" template code, to represent less than 8 bytes

 * of uncompressed data.  It is followed by a 3 bit arg N indicating how many

 * data bytes will follow, and then N bytes of data, which should be copied to

 * the output buffer.  This allows the software 842 compressor to accept input

 * buffers that are not an exact multiple of 8 bytes long.  However, those

 * compressed buffers containing this sw-only template will be rejected by

 * the 842 hardware decompressor, and must be decompressed with this software

 * library.  The 842 software compression module includes a parameter to

 * disable using this sw-only "short data" template, and instead simply

 * reject any input buffer that is not a multiple of 8 bytes long.

 *

 * After all actions for each operation code are processed, another template

 * code is in the next 5 bits.  The decompression ends once the "end" template

 * code is detected.

 */

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/bitops.h>

#include <asm/unaligned.h>

#include <linux/sw842.h>

/* special templates */

#define OP_REPEAT	(0x1B)

#define OP_ZEROS	(0x1C)

#define OP_END		(0x1E)

/* sw only template - this is not in the hw design; it's used only by this

 * software compressor and decompressor, to allow input buffers that aren't

 * a multiple of 8.

 */

#define OP_SHORT_DATA	(0x1D)

/* additional bits of each op param */

#define OP_BITS		(5)

#define REPEAT_BITS	(6)

#define SHORT_DATA_BITS	(3)

#define I2_BITS		(8)

#define I4_BITS		(9)

#define I8_BITS		(8)

#define REPEAT_BITS_MAX		(0x3f)

#define SHORT_DATA_BITS_MAX	(0x7)

/* Arbitrary values used to indicate action */

#define OP_ACTION	(0x70)

#define OP_ACTION_INDEX	(0x10)

#define OP_ACTION_DATA	(0x20)

#define OP_ACTION_NOOP	(0x40)

#define OP_AMOUNT	(0x0f)

#define OP_AMOUNT_0	(0x00)

#define OP_AMOUNT_2	(0x02)

#define OP_AMOUNT_4	(0x04)

#define OP_AMOUNT_8	(0x08)

#define D2		(OP_ACTION_DATA  | OP_AMOUNT_2)

#define D4		(OP_ACTION_DATA  | OP_AMOUNT_4)

#define D8		(OP_ACTION_DATA  | OP_AMOUNT_8)

#define I2		(OP_ACTION_INDEX | OP_AMOUNT_2)

#define I4		(OP_ACTION_INDEX | OP_AMOUNT_4)

#define I8		(OP_ACTION_INDEX | OP_AMOUNT_8)

#define N0		(OP_ACTION_NOOP  | OP_AMOUNT_0)

/* the max of the regular templates - not including the special templates */

#define OPS_MAX		(0x1a)

#endif

/*

 * 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