1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (C) 2014 Sergey Senozhatsky.
  4 */
  5
  6#include <linux/kernel.h>
  7#include <linux/string.h>
  8#include <linux/err.h>
  9#include <linux/slab.h>
 10#include <linux/wait.h>
 11#include <linux/sched.h>
 12#include <linux/cpu.h>
 13#include <linux/crypto.h>
 14
 15#include "zcomp.h"
 16
 17static const char * const backends[] = {
 18#if IS_ENABLED(CONFIG_CRYPTO_LZO)
 19	"lzo",
 20	"lzo-rle",
 21#endif
 22#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
 23	"lz4",
 24#endif
 25#if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
 26	"lz4hc",
 27#endif
 28#if IS_ENABLED(CONFIG_CRYPTO_842)
 29	"842",
 30#endif
 31#if IS_ENABLED(CONFIG_CRYPTO_ZSTD)
 32	"zstd",
 33#endif
 34};
 35
 36static void zcomp_strm_free(struct zcomp_strm *zstrm)
 37{
 38	if (!IS_ERR_OR_NULL(zstrm->tfm))
 39		crypto_free_comp(zstrm->tfm);
 40	free_pages((unsigned long)zstrm->buffer, 1);
 41	zstrm->tfm = NULL;
 42	zstrm->buffer = NULL;
 43}
 44
 45/*
 46 * Initialize zcomp_strm structure with ->tfm initialized by backend, and
 47 * ->buffer. Return a negative value on error.
 48 */
 49static int zcomp_strm_init(struct zcomp_strm *zstrm, struct zcomp *comp)
 50{
 51	zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
 52	/*
 53	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
 54	 * case when compressed size is larger than the original one
 55	 */
 56	zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
 57	if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
 58		zcomp_strm_free(zstrm);
 59		return -ENOMEM;
 60	}
 61	return 0;
 62}
 63
 64bool zcomp_available_algorithm(const char *comp)
 65{
 66	int i;
 67
 68	i = sysfs_match_string(backends, comp);
 69	if (i >= 0)
 70		return true;
 71
 72	/*
 73	 * Crypto does not ignore a trailing new line symbol,
 74	 * so make sure you don't supply a string containing
 75	 * one.
 76	 * This also means that we permit zcomp initialisation
 77	 * with any compressing algorithm known to crypto api.
 78	 */
 79	return crypto_has_comp(comp, 0, 0) == 1;
 80}
 81
 82/* show available compressors */
 83ssize_t zcomp_available_show(const char *comp, char *buf)
 84{
 85	bool known_algorithm = false;
 86	ssize_t sz = 0;
 87	int i;
 88
 89	for (i = 0; i < ARRAY_SIZE(backends); i++) {
 90		if (!strcmp(comp, backends[i])) {
 91			known_algorithm = true;
 92			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 93					"[%s] ", backends[i]);
 94		} else {
 95			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 96					"%s ", backends[i]);
 97		}
 98	}
 99
100	/*
101	 * Out-of-tree module known to crypto api or a missing
102	 * entry in `backends'.
103	 */
104	if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
105		sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
106				"[%s] ", comp);
107
108	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
109	return sz;
110}
111
112struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
113{
114	local_lock(&comp->stream->lock);
115	return this_cpu_ptr(comp->stream);
116}
117
118void zcomp_stream_put(struct zcomp *comp)
119{
120	local_unlock(&comp->stream->lock);
121}
122
123int zcomp_compress(struct zcomp_strm *zstrm,
124		const void *src, unsigned int *dst_len)
125{
126	/*
127	 * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
128	 * because sometimes we can endup having a bigger compressed data
129	 * due to various reasons: for example compression algorithms tend
130	 * to add some padding to the compressed buffer. Speaking of padding,
131	 * comp algorithm `842' pads the compressed length to multiple of 8
132	 * and returns -ENOSP when the dst memory is not big enough, which
133	 * is not something that ZRAM wants to see. We can handle the
134	 * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
135	 * receive -ERRNO from the compressing backend we can't help it
136	 * anymore. To make `842' happy we need to tell the exact size of
137	 * the dst buffer, zram_drv will take care of the fact that
138	 * compressed buffer is too big.
139	 */
140	*dst_len = PAGE_SIZE * 2;
141
142	return crypto_comp_compress(zstrm->tfm,
143			src, PAGE_SIZE,
144			zstrm->buffer, dst_len);
145}
146
147int zcomp_decompress(struct zcomp_strm *zstrm,
148		const void *src, unsigned int src_len, void *dst)
149{
150	unsigned int dst_len = PAGE_SIZE;
151
152	return crypto_comp_decompress(zstrm->tfm,
153			src, src_len,
154			dst, &dst_len);
155}
156
157int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
158{
159	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
160	struct zcomp_strm *zstrm;
161	int ret;
162
163	zstrm = per_cpu_ptr(comp->stream, cpu);
164	local_lock_init(&zstrm->lock);
165
166	ret = zcomp_strm_init(zstrm, comp);
167	if (ret)
168		pr_err("Can't allocate a compression stream\n");
169	return ret;
170}
171
172int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
173{
174	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
175	struct zcomp_strm *zstrm;
176
177	zstrm = per_cpu_ptr(comp->stream, cpu);
178	zcomp_strm_free(zstrm);
179	return 0;
180}
181
182static int zcomp_init(struct zcomp *comp)
183{
184	int ret;
185
186	comp->stream = alloc_percpu(struct zcomp_strm);
187	if (!comp->stream)
188		return -ENOMEM;
189
190	ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
191	if (ret < 0)
192		goto cleanup;
193	return 0;
194
195cleanup:
196	free_percpu(comp->stream);
197	return ret;
198}
199
200void zcomp_destroy(struct zcomp *comp)
201{
202	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
203	free_percpu(comp->stream);
204	kfree(comp);
205}
206
207/*
208 * search available compressors for requested algorithm.
209 * allocate new zcomp and initialize it. return compressing
210 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
211 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
212 * case of allocation error, or any other error potentially
213 * returned by zcomp_init().
214 */
215struct zcomp *zcomp_create(const char *compress)
216{
217	struct zcomp *comp;
218	int error;
219
220	if (!zcomp_available_algorithm(compress))
221		return ERR_PTR(-EINVAL);
222
223	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
224	if (!comp)
225		return ERR_PTR(-ENOMEM);
226
227	comp->name = compress;
228	error = zcomp_init(comp);
229	if (error) {
230		kfree(comp);
231		return ERR_PTR(error);
232	}
233	return comp;
234}