drivers/block/zram/zcomp.c

   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         "lzo",
  19         "lzo-rle",
  20 #if IS_ENABLED(CONFIG_CRYPTO_LZ4)
  21         "lz4",
  22 #endif
  23 #if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
  24         "lz4hc",
  25 #endif
  26 #if IS_ENABLED(CONFIG_CRYPTO_842)
  27         "842",
  28 #endif
  29 #if IS_ENABLED(CONFIG_CRYPTO_ZSTD)
  30         "zstd",
  31 #endif
  32         NULL
  33 };
  34
  35 static void zcomp_strm_free(struct zcomp_strm *zstrm)
  36 {
  37         if (!IS_ERR_OR_NULL(zstrm->tfm))
  38                 crypto_free_comp(zstrm->tfm);
  39         free_pages((unsigned long)zstrm->buffer, 1);
  40         kfree(zstrm);
  41 }
  42
  43 /*
  44  * allocate new zcomp_strm structure with ->tfm initialized by
  45  * backend, return NULL on error
  46  */
  47 static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
  48 {
  49         struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
  50         if (!zstrm)
  51                 return NULL;
  52
  53         zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
  54         /*
  55          * allocate 2 pages. 1 for compressed data, plus 1 extra for the
  56          * case when compressed size is larger than the original one
  57          */
  58         zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
  59         if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
  60                 zcomp_strm_free(zstrm);
  61                 zstrm = NULL;
  62         }
  63         return zstrm;
  64 }
  65
  66 bool zcomp_available_algorithm(const char *comp)
  67 {
  68         int i;
  69
  70         i = __sysfs_match_string(backends, -1, comp);
  71         if (i >= 0)
  72                 return true;
  73
  74         /*
  75          * Crypto does not ignore a trailing new line symbol,
  76          * so make sure you don't supply a string containing
  77          * one.
  78          * This also means that we permit zcomp initialisation
  79          * with any compressing algorithm known to crypto api.
  80          */
  81         return crypto_has_comp(comp, 0, 0) == 1;
  82 }
  83
  84 /* show available compressors */
  85 ssize_t zcomp_available_show(const char *comp, char *buf)
  86 {
  87         bool known_algorithm = false;
  88         ssize_t sz = 0;
  89         int i = 0;
  90
  91         for (; backends[i]; i++) {
  92                 if (!strcmp(comp, backends[i])) {
  93                         known_algorithm = true;
  94                         sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
  95                                         "[%s] ", backends[i]);
  96                 } else {
  97                         sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
  98                                         "%s ", backends[i]);
  99                 }
 100         }
 101
 102         /*
 103          * Out-of-tree module known to crypto api or a missing
 104          * entry in `backends'.
 105          */
 106         if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
 107                 sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 108                                 "[%s] ", comp);
 109
 110         sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
 111         return sz;
 112 }
 113
 114 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
 115 {
 116         return *get_cpu_ptr(comp->stream);
 117 }
 118
 119 void zcomp_stream_put(struct zcomp *comp)
 120 {
 121         put_cpu_ptr(comp->stream);
 122 }
 123
 124 int zcomp_compress(struct zcomp_strm *zstrm,
 125                 const void *src, unsigned int *dst_len)
 126 {
 127         /*
 128          * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
 129          * because sometimes we can endup having a bigger compressed data
 130          * due to various reasons: for example compression algorithms tend
 131          * to add some padding to the compressed buffer. Speaking of padding,
 132          * comp algorithm `842' pads the compressed length to multiple of 8
 133          * and returns -ENOSP when the dst memory is not big enough, which
 134          * is not something that ZRAM wants to see. We can handle the
 135          * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
 136          * receive -ERRNO from the compressing backend we can't help it
 137          * anymore. To make `842' happy we need to tell the exact size of
 138          * the dst buffer, zram_drv will take care of the fact that
 139          * compressed buffer is too big.
 140          */
 141         *dst_len = PAGE_SIZE * 2;
 142
 143         return crypto_comp_compress(zstrm->tfm,
 144                         src, PAGE_SIZE,
 145                         zstrm->buffer, dst_len);
 146 }
 147
 148 int zcomp_decompress(struct zcomp_strm *zstrm,
 149                 const void *src, unsigned int src_len, void *dst)
 150 {
 151         unsigned int dst_len = PAGE_SIZE;
 152
 153         return crypto_comp_decompress(zstrm->tfm,
 154                         src, src_len,
 155                         dst, &dst_len);
 156 }
 157
 158 int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
 159 {
 160         struct zcomp *comp = hlist_entry(node, struct zcomp, node);
 161         struct zcomp_strm *zstrm;
 162
 163         if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))
 164                 return 0;
 165
 166         zstrm = zcomp_strm_alloc(comp);
 167         if (IS_ERR_OR_NULL(zstrm)) {
 168                 pr_err("Can't allocate a compression stream\n");
 169                 return -ENOMEM;
 170         }
 171         *per_cpu_ptr(comp->stream, cpu) = zstrm;
 172         return 0;
 173 }
 174
 175 int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
 176 {
 177         struct zcomp *comp = hlist_entry(node, struct zcomp, node);
 178         struct zcomp_strm *zstrm;
 179
 180         zstrm = *per_cpu_ptr(comp->stream, cpu);
 181         if (!IS_ERR_OR_NULL(zstrm))
 182                 zcomp_strm_free(zstrm);
 183         *per_cpu_ptr(comp->stream, cpu) = NULL;
 184         return 0;
 185 }
 186
 187 static int zcomp_init(struct zcomp *comp)
 188 {
 189         int ret;
 190
 191         comp->stream = alloc_percpu(struct zcomp_strm *);
 192         if (!comp->stream)
 193                 return -ENOMEM;
 194
 195         ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
 196         if (ret < 0)
 197                 goto cleanup;
 198         return 0;
 199
 200 cleanup:
 201         free_percpu(comp->stream);
 202         return ret;
 203 }
 204
 205 void zcomp_destroy(struct zcomp *comp)
 206 {
 207         cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
 208         free_percpu(comp->stream);
 209         kfree(comp);
 210 }
 211
 212 /*
 213  * search available compressors for requested algorithm.
 214  * allocate new zcomp and initialize it. return compressing
 215  * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
 216  * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
 217  * case of allocation error, or any other error potentially
 218  * returned by zcomp_init().
 219  */
 220 struct zcomp *zcomp_create(const char *compress)
 221 {
 222         struct zcomp *comp;
 223         int error;
 224
 225         if (!zcomp_available_algorithm(compress))
 226                 return ERR_PTR(-EINVAL);
 227
 228         comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
 229         if (!comp)
 230                 return ERR_PTR(-ENOMEM);
 231
 232         comp->name = compress;
 233         error = zcomp_init(comp);
 234         if (error) {
 235                 kfree(comp);
 236                 return ERR_PTR(error);
 237         }
 238         return comp;
 239 }