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