xref: /openbmc/linux/drivers/block/zram/zcomp.c (revision e5bd61e8)
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 
17 static 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 
36 static 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  */
49 static 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 
64 bool 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 */
83 ssize_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 
112 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
113 {
114 	local_lock(&comp->stream->lock);
115 	return this_cpu_ptr(comp->stream);
116 }
117 
118 void zcomp_stream_put(struct zcomp *comp)
119 {
120 	local_unlock(&comp->stream->lock);
121 }
122 
123 int 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 
147 int 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 
157 int 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 
172 int 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 
182 static 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 
195 cleanup:
196 	free_percpu(comp->stream);
197 	return ret;
198 }
199 
200 void 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  */
215 struct 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 }
235