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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2014 Sergey Senozhatsky.
*/
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/cpu.h>
#include <linux/crypto.h>
#include "zcomp.h"
static const char * const backends[] = {
#if IS_ENABLED(CONFIG_CRYPTO_LZO)
"lzo",
"lzo-rle",
#endif
#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
"lz4",
#endif
#if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
"lz4hc",
#endif
#if IS_ENABLED(CONFIG_CRYPTO_842)
"842",
#endif
#if IS_ENABLED(CONFIG_CRYPTO_ZSTD)
"zstd",
#endif
};
static void zcomp_strm_free(struct zcomp_strm *zstrm)
{
if (!IS_ERR_OR_NULL(zstrm->tfm))
crypto_free_comp(zstrm->tfm);
free_pages((unsigned long)zstrm->buffer, 1);
zstrm->tfm = NULL;
zstrm->buffer = NULL;
}
/*
* Initialize zcomp_strm structure with ->tfm initialized by backend, and
* ->buffer. Return a negative value on error.
*/
static int zcomp_strm_init(struct zcomp_strm *zstrm, struct zcomp *comp)
{
zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
/*
* allocate 2 pages. 1 for compressed data, plus 1 extra for the
* case when compressed size is larger than the original one
*/
zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
zcomp_strm_free(zstrm);
return -ENOMEM;
}
return 0;
}
bool zcomp_available_algorithm(const char *comp)
{
/*
* Crypto does not ignore a trailing new line symbol,
* so make sure you don't supply a string containing
* one.
* This also means that we permit zcomp initialisation
* with any compressing algorithm known to crypto api.
*/
return crypto_has_comp(comp, 0, 0) == 1;
}
/* show available compressors */
ssize_t zcomp_available_show(const char *comp, char *buf)
{
bool known_algorithm = false;
ssize_t sz = 0;
int i;
for (i = 0; i < ARRAY_SIZE(backends); i++) {
if (!strcmp(comp, backends[i])) {
known_algorithm = true;
sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
"[%s] ", backends[i]);
} else {
sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
"%s ", backends[i]);
}
}
/*
* Out-of-tree module known to crypto api or a missing
* entry in `backends'.
*/
if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
"[%s] ", comp);
sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
return sz;
}
struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
{
local_lock(&comp->stream->lock);
return this_cpu_ptr(comp->stream);
}
void zcomp_stream_put(struct zcomp *comp)
{
local_unlock(&comp->stream->lock);
}
int zcomp_compress(struct zcomp_strm *zstrm,
const void *src, unsigned int *dst_len)
{
/*
* Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
* because sometimes we can endup having a bigger compressed data
* due to various reasons: for example compression algorithms tend
* to add some padding to the compressed buffer. Speaking of padding,
* comp algorithm `842' pads the compressed length to multiple of 8
* and returns -ENOSP when the dst memory is not big enough, which
* is not something that ZRAM wants to see. We can handle the
* `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
* receive -ERRNO from the compressing backend we can't help it
* anymore. To make `842' happy we need to tell the exact size of
* the dst buffer, zram_drv will take care of the fact that
* compressed buffer is too big.
*/
*dst_len = PAGE_SIZE * 2;
return crypto_comp_compress(zstrm->tfm,
src, PAGE_SIZE,
zstrm->buffer, dst_len);
}
int zcomp_decompress(struct zcomp_strm *zstrm,
const void *src, unsigned int src_len, void *dst)
{
unsigned int dst_len = PAGE_SIZE;
return crypto_comp_decompress(zstrm->tfm,
src, src_len,
dst, &dst_len);
}
int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zcomp *comp = hlist_entry(node, struct zcomp, node);
struct zcomp_strm *zstrm;
int ret;
zstrm = per_cpu_ptr(comp->stream, cpu);
local_lock_init(&zstrm->lock);
ret = zcomp_strm_init(zstrm, comp);
if (ret)
pr_err("Can't allocate a compression stream\n");
return ret;
}
int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
{
struct zcomp *comp = hlist_entry(node, struct zcomp, node);
struct zcomp_strm *zstrm;
zstrm = per_cpu_ptr(comp->stream, cpu);
zcomp_strm_free(zstrm);
return 0;
}
static int zcomp_init(struct zcomp *comp)
{
int ret;
comp->stream = alloc_percpu(struct zcomp_strm);
if (!comp->stream)
return -ENOMEM;
ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
if (ret < 0)
goto cleanup;
return 0;
cleanup:
free_percpu(comp->stream);
return ret;
}
void zcomp_destroy(struct zcomp *comp)
{
cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
free_percpu(comp->stream);
kfree(comp);
}
/*
* search available compressors for requested algorithm.
* allocate new zcomp and initialize it. return compressing
* backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
* if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
* case of allocation error, or any other error potentially
* returned by zcomp_init().
*/
struct zcomp *zcomp_create(const char *alg)
{
struct zcomp *comp;
int error;
/*
* Crypto API will execute /sbin/modprobe if the compression module
* is not loaded yet. We must do it here, otherwise we are about to
* call /sbin/modprobe under CPU hot-plug lock.
*/
if (!zcomp_available_algorithm(alg))
return ERR_PTR(-EINVAL);
comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
if (!comp)
return ERR_PTR(-ENOMEM);
comp->name = alg;
error = zcomp_init(comp);
if (error) {
kfree(comp);
return ERR_PTR(error);
}
return comp;
}
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