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_DEFLATE)
27 "deflate",
28 #endif
29 #if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
30 "lz4hc",
31 #endif
32 #if IS_ENABLED(CONFIG_CRYPTO_842)
33 "842",
34 #endif
35 NULL
36 };
37
zcomp_strm_free(struct zcomp_strm * zstrm)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 */
zcomp_strm_alloc(struct zcomp * comp)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
zcomp_available_algorithm(const char * comp)69 bool zcomp_available_algorithm(const char *comp)
70 {
71 int i = 0;
72
73 while (backends[i]) {
74 if (sysfs_streq(comp, backends[i]))
75 return true;
76 i++;
77 }
78
79 /*
80 * Crypto does not ignore a trailing new line symbol,
81 * so make sure you don't supply a string containing
82 * one.
83 * This also means that we permit zcomp initialisation
84 * with any compressing algorithm known to crypto api.
85 */
86 return crypto_has_comp(comp, 0, 0) == 1;
87 }
88
89 /* show available compressors */
zcomp_available_show(const char * comp,char * buf)90 ssize_t zcomp_available_show(const char *comp, char *buf)
91 {
92 bool known_algorithm = false;
93 ssize_t sz = 0;
94 int i = 0;
95
96 for (; backends[i]; i++) {
97 if (!strcmp(comp, backends[i])) {
98 known_algorithm = true;
99 sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
100 "[%s] ", backends[i]);
101 } else {
102 sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
103 "%s ", backends[i]);
104 }
105 }
106
107 /*
108 * Out-of-tree module known to crypto api or a missing
109 * entry in `backends'.
110 */
111 if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
112 sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
113 "[%s] ", comp);
114
115 sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
116 return sz;
117 }
118
zcomp_stream_get(struct zcomp * comp)119 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
120 {
121 return *get_cpu_ptr(comp->stream);
122 }
123
zcomp_stream_put(struct zcomp * comp)124 void zcomp_stream_put(struct zcomp *comp)
125 {
126 put_cpu_ptr(comp->stream);
127 }
128
zcomp_compress(struct zcomp_strm * zstrm,const void * src,unsigned int * dst_len)129 int zcomp_compress(struct zcomp_strm *zstrm,
130 const void *src, unsigned int *dst_len)
131 {
132 /*
133 * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
134 * because sometimes we can endup having a bigger compressed data
135 * due to various reasons: for example compression algorithms tend
136 * to add some padding to the compressed buffer. Speaking of padding,
137 * comp algorithm `842' pads the compressed length to multiple of 8
138 * and returns -ENOSP when the dst memory is not big enough, which
139 * is not something that ZRAM wants to see. We can handle the
140 * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
141 * receive -ERRNO from the compressing backend we can't help it
142 * anymore. To make `842' happy we need to tell the exact size of
143 * the dst buffer, zram_drv will take care of the fact that
144 * compressed buffer is too big.
145 */
146 *dst_len = PAGE_SIZE * 2;
147
148 return crypto_comp_compress(zstrm->tfm,
149 src, PAGE_SIZE,
150 zstrm->buffer, dst_len);
151 }
152
zcomp_decompress(struct zcomp_strm * zstrm,const void * src,unsigned int src_len,void * dst)153 int zcomp_decompress(struct zcomp_strm *zstrm,
154 const void *src, unsigned int src_len, void *dst)
155 {
156 unsigned int dst_len = PAGE_SIZE;
157
158 return crypto_comp_decompress(zstrm->tfm,
159 src, src_len,
160 dst, &dst_len);
161 }
162
__zcomp_cpu_notifier(struct zcomp * comp,unsigned long action,unsigned long cpu)163 static int __zcomp_cpu_notifier(struct zcomp *comp,
164 unsigned long action, unsigned long cpu)
165 {
166 struct zcomp_strm *zstrm;
167
168 switch (action) {
169 case CPU_UP_PREPARE:
170 if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))
171 break;
172 zstrm = zcomp_strm_alloc(comp);
173 if (IS_ERR_OR_NULL(zstrm)) {
174 pr_err("Can't allocate a compression stream\n");
175 return NOTIFY_BAD;
176 }
177 *per_cpu_ptr(comp->stream, cpu) = zstrm;
178 break;
179 case CPU_DEAD:
180 case CPU_UP_CANCELED:
181 zstrm = *per_cpu_ptr(comp->stream, cpu);
182 if (!IS_ERR_OR_NULL(zstrm))
183 zcomp_strm_free(zstrm);
184 *per_cpu_ptr(comp->stream, cpu) = NULL;
185 break;
186 default:
187 break;
188 }
189 return NOTIFY_OK;
190 }
191
zcomp_cpu_notifier(struct notifier_block * nb,unsigned long action,void * pcpu)192 static int zcomp_cpu_notifier(struct notifier_block *nb,
193 unsigned long action, void *pcpu)
194 {
195 unsigned long cpu = (unsigned long)pcpu;
196 struct zcomp *comp = container_of(nb, typeof(*comp), notifier);
197
198 return __zcomp_cpu_notifier(comp, action, cpu);
199 }
200
zcomp_init(struct zcomp * comp)201 static int zcomp_init(struct zcomp *comp)
202 {
203 unsigned long cpu;
204 int ret;
205
206 comp->notifier.notifier_call = zcomp_cpu_notifier;
207
208 comp->stream = alloc_percpu(struct zcomp_strm *);
209 if (!comp->stream)
210 return -ENOMEM;
211
212 cpu_notifier_register_begin();
213 for_each_online_cpu(cpu) {
214 ret = __zcomp_cpu_notifier(comp, CPU_UP_PREPARE, cpu);
215 if (ret == NOTIFY_BAD)
216 goto cleanup;
217 }
218 __register_cpu_notifier(&comp->notifier);
219 cpu_notifier_register_done();
220 return 0;
221
222 cleanup:
223 for_each_online_cpu(cpu)
224 __zcomp_cpu_notifier(comp, CPU_UP_CANCELED, cpu);
225 cpu_notifier_register_done();
226 return -ENOMEM;
227 }
228
zcomp_destroy(struct zcomp * comp)229 void zcomp_destroy(struct zcomp *comp)
230 {
231 unsigned long cpu;
232
233 cpu_notifier_register_begin();
234 for_each_online_cpu(cpu)
235 __zcomp_cpu_notifier(comp, CPU_UP_CANCELED, cpu);
236 __unregister_cpu_notifier(&comp->notifier);
237 cpu_notifier_register_done();
238
239 free_percpu(comp->stream);
240 kfree(comp);
241 }
242
243 /*
244 * search available compressors for requested algorithm.
245 * allocate new zcomp and initialize it. return compressing
246 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
247 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
248 * case of allocation error, or any other error potentially
249 * returned by zcomp_init().
250 */
zcomp_create(const char * compress)251 struct zcomp *zcomp_create(const char *compress)
252 {
253 struct zcomp *comp;
254 int error;
255
256 if (!zcomp_available_algorithm(compress))
257 return ERR_PTR(-EINVAL);
258
259 comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
260 if (!comp)
261 return ERR_PTR(-ENOMEM);
262
263 comp->name = compress;
264 error = zcomp_init(comp);
265 if (error) {
266 kfree(comp);
267 return ERR_PTR(error);
268 }
269 return comp;
270 }
271