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
zcomp_strm_free(struct zcomp_strm * zstrm)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 */
zcomp_strm_init(struct zcomp_strm * zstrm,struct zcomp * comp)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
zcomp_available_algorithm(const char * comp)64 bool 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 */
zcomp_available_show(const char * comp,char * buf)77 ssize_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
zcomp_stream_get(struct zcomp * comp)106 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
107 {
108 local_lock(&comp->stream->lock);
109 return this_cpu_ptr(comp->stream);
110 }
111
zcomp_stream_put(struct zcomp * comp)112 void zcomp_stream_put(struct zcomp *comp)
113 {
114 local_unlock(&comp->stream->lock);
115 }
116
zcomp_compress(struct zcomp_strm * zstrm,const void * src,unsigned int * dst_len)117 int 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
zcomp_decompress(struct zcomp_strm * zstrm,const void * src,unsigned int src_len,void * dst)141 int 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
zcomp_cpu_up_prepare(unsigned int cpu,struct hlist_node * node)151 int 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
zcomp_cpu_dead(unsigned int cpu,struct hlist_node * node)166 int 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
zcomp_init(struct zcomp * comp)176 static 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
189 cleanup:
190 free_percpu(comp->stream);
191 return ret;
192 }
193
zcomp_destroy(struct zcomp * comp)194 void 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 */
zcomp_create(const char * alg)209 struct 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