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	/*
67	 * Crypto does not ignore a trailing new line symbol,
68	 * so make sure you don't supply a string containing
69	 * one.
70	 * This also means that we permit zcomp initialisation
71	 * with any compressing algorithm known to crypto api.
72	 */
73	return crypto_has_comp(comp, 0, 0) == 1;
74}
75
76/* show available compressors */
77ssize_t zcomp_available_show(const char *comp, char *buf)
78{
79	bool known_algorithm = false;
80	ssize_t sz = 0;
81	int i;
82
83	for (i = 0; i < ARRAY_SIZE(backends); i++) {
84		if (!strcmp(comp, backends[i])) {
85			known_algorithm = true;
86			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
87					"[%s] ", backends[i]);
88		} else {
89			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
90					"%s ", backends[i]);
91		}
92	}
93
94	/*
95	 * Out-of-tree module known to crypto api or a missing
96	 * entry in `backends'.
97	 */
98	if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
99		sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
100				"[%s] ", comp);
101
102	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
103	return sz;
104}
105
106struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
107{
108	local_lock(&comp->stream->lock);
109	return this_cpu_ptr(comp->stream);
110}
111
112void zcomp_stream_put(struct zcomp *comp)
113{
114	local_unlock(&comp->stream->lock);
115}
116
117int zcomp_compress(struct zcomp_strm *zstrm,
118		const void *src, unsigned int *dst_len)
119{
120	/*
121	 * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
122	 * because sometimes we can endup having a bigger compressed data
123	 * due to various reasons: for example compression algorithms tend
124	 * to add some padding to the compressed buffer. Speaking of padding,
125	 * comp algorithm `842' pads the compressed length to multiple of 8
126	 * and returns -ENOSP when the dst memory is not big enough, which
127	 * is not something that ZRAM wants to see. We can handle the
128	 * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
129	 * receive -ERRNO from the compressing backend we can't help it
130	 * anymore. To make `842' happy we need to tell the exact size of
131	 * the dst buffer, zram_drv will take care of the fact that
132	 * compressed buffer is too big.
133	 */
134	*dst_len = PAGE_SIZE * 2;
135
136	return crypto_comp_compress(zstrm->tfm,
137			src, PAGE_SIZE,
138			zstrm->buffer, dst_len);
139}
140
141int zcomp_decompress(struct zcomp_strm *zstrm,
142		const void *src, unsigned int src_len, void *dst)
143{
144	unsigned int dst_len = PAGE_SIZE;
145
146	return crypto_comp_decompress(zstrm->tfm,
147			src, src_len,
148			dst, &dst_len);
149}
150
151int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
152{
153	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
154	struct zcomp_strm *zstrm;
155	int ret;
156
157	zstrm = per_cpu_ptr(comp->stream, cpu);
158	local_lock_init(&zstrm->lock);
159
160	ret = zcomp_strm_init(zstrm, comp);
161	if (ret)
162		pr_err("Can't allocate a compression stream\n");
163	return ret;
164}
165
166int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
167{
168	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
169	struct zcomp_strm *zstrm;
170
171	zstrm = per_cpu_ptr(comp->stream, cpu);
172	zcomp_strm_free(zstrm);
173	return 0;
174}
175
176static int zcomp_init(struct zcomp *comp)
177{
178	int ret;
179
180	comp->stream = alloc_percpu(struct zcomp_strm);
181	if (!comp->stream)
182		return -ENOMEM;
183
184	ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
185	if (ret < 0)
186		goto cleanup;
187	return 0;
188
189cleanup:
190	free_percpu(comp->stream);
191	return ret;
192}
193
194void zcomp_destroy(struct zcomp *comp)
195{
196	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
197	free_percpu(comp->stream);
198	kfree(comp);
199}
200
201/*
202 * search available compressors for requested algorithm.
203 * allocate new zcomp and initialize it. return compressing
204 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
205 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
206 * case of allocation error, or any other error potentially
207 * returned by zcomp_init().
208 */
209struct zcomp *zcomp_create(const char *alg)
210{
211	struct zcomp *comp;
212	int error;
213
214	/*
215	 * Crypto API will execute /sbin/modprobe if the compression module
216	 * is not loaded yet. We must do it here, otherwise we are about to
217	 * call /sbin/modprobe under CPU hot-plug lock.
218	 */
219	if (!zcomp_available_algorithm(alg))
220		return ERR_PTR(-EINVAL);
221
222	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
223	if (!comp)
224		return ERR_PTR(-ENOMEM);
225
226	comp->name = alg;
227	error = zcomp_init(comp);
228	if (error) {
229		kfree(comp);
230		return ERR_PTR(error);
231	}
232	return comp;
233}
234