lib: add software 842 compression/decompression

Add 842-format software compression and decompression functions.
Update the MAINTAINERS 842 section to include the new files.

The 842 compression function can compress any input data into the 842
compression format.  The 842 decompression function can decompress any
standard-format 842 compressed data - specifically, either a compressed
data buffer created by the 842 software compression function, or a
compressed data buffer created by the 842 hardware compressor (located
in PowerPC coprocessors).

The 842 compressed data format is explained in the header comments.

This is used in a later patch to provide a full software 842 compression
and decompression crypto interface.

Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 626 insertions, 0 deletions

diff --git a/lib/842/842_compress.c b/lib/842/842_compress.c
new file mode 100644
index 000000000000..7ce68948e68c
--- /dev/null
+++ b/lib/842/842_compress.c
@@ -0,0 +1,626 @@
+/*
+ * 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>");