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#include <linux/vmalloc.h>
15
16#include "zcomp.h"
17
18static const char * const backends[] = {
19#if IS_ENABLED(CONFIG_CRYPTO_LZO)
20	"lzo",
21	"lzo-rle",
22#endif
23#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
24	"lz4",
25#endif
26#if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
27	"lz4hc",
28#endif
29#if IS_ENABLED(CONFIG_CRYPTO_842)
30	"842",
31#endif
32#if IS_ENABLED(CONFIG_CRYPTO_ZSTD)
33	"zstd",
34#endif
35};
36
37static void zcomp_strm_free(struct zcomp_strm *zstrm)
38{
39	if (!IS_ERR_OR_NULL(zstrm->tfm))
40		crypto_free_comp(zstrm->tfm);
41	vfree(zstrm->buffer);
42	zstrm->tfm = NULL;
43	zstrm->buffer = NULL;
44}
45
46/*
47 * Initialize zcomp_strm structure with ->tfm initialized by backend, and
48 * ->buffer. Return a negative value on error.
49 */
50static int zcomp_strm_init(struct zcomp_strm *zstrm, struct zcomp *comp)
51{
52	zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
53	/*
54	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
55	 * case when compressed size is larger than the original one
56	 */
57	zstrm->buffer = vzalloc(2 * PAGE_SIZE);
58	if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
59		zcomp_strm_free(zstrm);
60		return -ENOMEM;
61	}
62	return 0;
63}
64
65bool zcomp_available_algorithm(const char *comp)
66{
67	/*
68	 * Crypto does not ignore a trailing new line symbol,
69	 * so make sure you don't supply a string containing
70	 * one.
71	 * This also means that we permit zcomp initialisation
72	 * with any compressing algorithm known to crypto api.
73	 */
74	return crypto_has_comp(comp, 0, 0) == 1;
75}
76
77/* show available compressors */
78ssize_t zcomp_available_show(const char *comp, char *buf)
79{
80	bool known_algorithm = false;
81	ssize_t sz = 0;
82	int i;
83
84	for (i = 0; i < ARRAY_SIZE(backends); i++) {
85		if (!strcmp(comp, backends[i])) {
86			known_algorithm = true;
87			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
88					"[%s] ", backends[i]);
89		} else {
90			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
91					"%s ", backends[i]);
92		}
93	}
94
95	/*
96	 * Out-of-tree module known to crypto api or a missing
97	 * entry in `backends'.
98	 */
99	if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
100		sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
101				"[%s] ", comp);
102
103	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
104	return sz;
105}
106
107struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
108{
109	local_lock(&comp->stream->lock);
110	return this_cpu_ptr(comp->stream);
111}
112
113void zcomp_stream_put(struct zcomp *comp)
114{
115	local_unlock(&comp->stream->lock);
116}
117
118int zcomp_compress(struct zcomp_strm *zstrm,
119		const void *src, unsigned int *dst_len)
120{
121	/*
122	 * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
123	 * because sometimes we can endup having a bigger compressed data
124	 * due to various reasons: for example compression algorithms tend
125	 * to add some padding to the compressed buffer. Speaking of padding,
126	 * comp algorithm `842' pads the compressed length to multiple of 8
127	 * and returns -ENOSP when the dst memory is not big enough, which
128	 * is not something that ZRAM wants to see. We can handle the
129	 * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
130	 * receive -ERRNO from the compressing backend we can't help it
131	 * anymore. To make `842' happy we need to tell the exact size of
132	 * the dst buffer, zram_drv will take care of the fact that
133	 * compressed buffer is too big.
134	 */
135	*dst_len = PAGE_SIZE * 2;
136
137	return crypto_comp_compress(zstrm->tfm,
138			src, PAGE_SIZE,
139			zstrm->buffer, dst_len);
140}
141
142int zcomp_decompress(struct zcomp_strm *zstrm,
143		const void *src, unsigned int src_len, void *dst)
144{
145	unsigned int dst_len = PAGE_SIZE;
146
147	return crypto_comp_decompress(zstrm->tfm,
148			src, src_len,
149			dst, &dst_len);
150}
151
152int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
153{
154	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
155	struct zcomp_strm *zstrm;
156	int ret;
157
158	zstrm = per_cpu_ptr(comp->stream, cpu);
159	local_lock_init(&zstrm->lock);
160
161	ret = zcomp_strm_init(zstrm, comp);
162	if (ret)
163		pr_err("Can't allocate a compression stream\n");
164	return ret;
165}
166
167int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
168{
169	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
170	struct zcomp_strm *zstrm;
171
172	zstrm = per_cpu_ptr(comp->stream, cpu);
173	zcomp_strm_free(zstrm);
174	return 0;
175}
176
177static int zcomp_init(struct zcomp *comp)
178{
179	int ret;
180
181	comp->stream = alloc_percpu(struct zcomp_strm);
182	if (!comp->stream)
183		return -ENOMEM;
184
185	ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
186	if (ret < 0)
187		goto cleanup;
188	return 0;
189
190cleanup:
191	free_percpu(comp->stream);
192	return ret;
193}
194
195void zcomp_destroy(struct zcomp *comp)
196{
197	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
198	free_percpu(comp->stream);
199	kfree(comp);
200}
201
202/*
203 * search available compressors for requested algorithm.
204 * allocate new zcomp and initialize it. return compressing
205 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
206 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
207 * case of allocation error, or any other error potentially
208 * returned by zcomp_init().
209 */
210struct zcomp *zcomp_create(const char *alg)
211{
212	struct zcomp *comp;
213	int error;
214
215	/*
216	 * Crypto API will execute /sbin/modprobe if the compression module
217	 * is not loaded yet. We must do it here, otherwise we are about to
218	 * call /sbin/modprobe under CPU hot-plug lock.
219	 */
220	if (!zcomp_available_algorithm(alg))
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 = alg;
228	error = zcomp_init(comp);
229	if (error) {
230		kfree(comp);
231		return ERR_PTR(error);
232	}
233	return comp;
234}
235