xref: /openbmc/linux/drivers/block/zram/zcomp.c (revision 6da2ec56)
1 /*
2  * Copyright (C) 2014 Sergey Senozhatsky.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License
6  * as published by the Free Software Foundation; either version
7  * 2 of the License, or (at your option) any later version.
8  */
9 
10 #include <linux/kernel.h>
11 #include <linux/string.h>
12 #include <linux/err.h>
13 #include <linux/slab.h>
14 #include <linux/wait.h>
15 #include <linux/sched.h>
16 #include <linux/cpu.h>
17 #include <linux/crypto.h>
18 
19 #include "zcomp.h"
20 
21 static const char * const backends[] = {
22 	"lzo",
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 	NULL
36 };
37 
38 static void zcomp_strm_free(struct zcomp_strm *zstrm)
39 {
40 	if (!IS_ERR_OR_NULL(zstrm->tfm))
41 		crypto_free_comp(zstrm->tfm);
42 	free_pages((unsigned long)zstrm->buffer, 1);
43 	kfree(zstrm);
44 }
45 
46 /*
47  * allocate new zcomp_strm structure with ->tfm initialized by
48  * backend, return NULL on error
49  */
50 static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
51 {
52 	struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
53 	if (!zstrm)
54 		return NULL;
55 
56 	zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
57 	/*
58 	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
59 	 * case when compressed size is larger than the original one
60 	 */
61 	zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
62 	if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
63 		zcomp_strm_free(zstrm);
64 		zstrm = NULL;
65 	}
66 	return zstrm;
67 }
68 
69 bool zcomp_available_algorithm(const char *comp)
70 {
71 	int i;
72 
73 	i = __sysfs_match_string(backends, -1, comp);
74 	if (i >= 0)
75 		return true;
76 
77 	/*
78 	 * Crypto does not ignore a trailing new line symbol,
79 	 * so make sure you don't supply a string containing
80 	 * one.
81 	 * This also means that we permit zcomp initialisation
82 	 * with any compressing algorithm known to crypto api.
83 	 */
84 	return crypto_has_comp(comp, 0, 0) == 1;
85 }
86 
87 /* show available compressors */
88 ssize_t zcomp_available_show(const char *comp, char *buf)
89 {
90 	bool known_algorithm = false;
91 	ssize_t sz = 0;
92 	int i = 0;
93 
94 	for (; backends[i]; i++) {
95 		if (!strcmp(comp, backends[i])) {
96 			known_algorithm = true;
97 			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
98 					"[%s] ", backends[i]);
99 		} else {
100 			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
101 					"%s ", backends[i]);
102 		}
103 	}
104 
105 	/*
106 	 * Out-of-tree module known to crypto api or a missing
107 	 * entry in `backends'.
108 	 */
109 	if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
110 		sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
111 				"[%s] ", comp);
112 
113 	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
114 	return sz;
115 }
116 
117 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
118 {
119 	return *get_cpu_ptr(comp->stream);
120 }
121 
122 void zcomp_stream_put(struct zcomp *comp)
123 {
124 	put_cpu_ptr(comp->stream);
125 }
126 
127 int zcomp_compress(struct zcomp_strm *zstrm,
128 		const void *src, unsigned int *dst_len)
129 {
130 	/*
131 	 * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
132 	 * because sometimes we can endup having a bigger compressed data
133 	 * due to various reasons: for example compression algorithms tend
134 	 * to add some padding to the compressed buffer. Speaking of padding,
135 	 * comp algorithm `842' pads the compressed length to multiple of 8
136 	 * and returns -ENOSP when the dst memory is not big enough, which
137 	 * is not something that ZRAM wants to see. We can handle the
138 	 * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
139 	 * receive -ERRNO from the compressing backend we can't help it
140 	 * anymore. To make `842' happy we need to tell the exact size of
141 	 * the dst buffer, zram_drv will take care of the fact that
142 	 * compressed buffer is too big.
143 	 */
144 	*dst_len = PAGE_SIZE * 2;
145 
146 	return crypto_comp_compress(zstrm->tfm,
147 			src, PAGE_SIZE,
148 			zstrm->buffer, dst_len);
149 }
150 
151 int zcomp_decompress(struct zcomp_strm *zstrm,
152 		const void *src, unsigned int src_len, void *dst)
153 {
154 	unsigned int dst_len = PAGE_SIZE;
155 
156 	return crypto_comp_decompress(zstrm->tfm,
157 			src, src_len,
158 			dst, &dst_len);
159 }
160 
161 int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
162 {
163 	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
164 	struct zcomp_strm *zstrm;
165 
166 	if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))
167 		return 0;
168 
169 	zstrm = zcomp_strm_alloc(comp);
170 	if (IS_ERR_OR_NULL(zstrm)) {
171 		pr_err("Can't allocate a compression stream\n");
172 		return -ENOMEM;
173 	}
174 	*per_cpu_ptr(comp->stream, cpu) = zstrm;
175 	return 0;
176 }
177 
178 int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
179 {
180 	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
181 	struct zcomp_strm *zstrm;
182 
183 	zstrm = *per_cpu_ptr(comp->stream, cpu);
184 	if (!IS_ERR_OR_NULL(zstrm))
185 		zcomp_strm_free(zstrm);
186 	*per_cpu_ptr(comp->stream, cpu) = NULL;
187 	return 0;
188 }
189 
190 static int zcomp_init(struct zcomp *comp)
191 {
192 	int ret;
193 
194 	comp->stream = alloc_percpu(struct zcomp_strm *);
195 	if (!comp->stream)
196 		return -ENOMEM;
197 
198 	ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
199 	if (ret < 0)
200 		goto cleanup;
201 	return 0;
202 
203 cleanup:
204 	free_percpu(comp->stream);
205 	return ret;
206 }
207 
208 void zcomp_destroy(struct zcomp *comp)
209 {
210 	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
211 	free_percpu(comp->stream);
212 	kfree(comp);
213 }
214 
215 /*
216  * search available compressors for requested algorithm.
217  * allocate new zcomp and initialize it. return compressing
218  * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
219  * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
220  * case of allocation error, or any other error potentially
221  * returned by zcomp_init().
222  */
223 struct zcomp *zcomp_create(const char *compress)
224 {
225 	struct zcomp *comp;
226 	int error;
227 
228 	if (!zcomp_available_algorithm(compress))
229 		return ERR_PTR(-EINVAL);
230 
231 	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
232 	if (!comp)
233 		return ERR_PTR(-ENOMEM);
234 
235 	comp->name = compress;
236 	error = zcomp_init(comp);
237 	if (error) {
238 		kfree(comp);
239 		return ERR_PTR(error);
240 	}
241 	return comp;
242 }
243