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
17static 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};
33
34static void zcomp_strm_free(struct zcomp_strm *zstrm)
35{
36	if (!IS_ERR_OR_NULL(zstrm->tfm))
37		crypto_free_comp(zstrm->tfm);
38	free_pages((unsigned long)zstrm->buffer, 1);
39	zstrm->tfm = NULL;
40	zstrm->buffer = NULL;
41}
42
43/*
44 * Initialize zcomp_strm structure with ->tfm initialized by backend, and
45 * ->buffer. Return a negative value on error.
46 */
47static int zcomp_strm_init(struct zcomp_strm *zstrm, struct zcomp *comp)
48{
49	zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
50	/*
51	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
52	 * case when compressed size is larger than the original one
53	 */
54	zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
55	if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
56		zcomp_strm_free(zstrm);
57		return -ENOMEM;
58	}
59	return 0;
60}
61
62bool zcomp_available_algorithm(const char *comp)
63{
64	/*
65	 * Crypto does not ignore a trailing new line symbol,
66	 * so make sure you don't supply a string containing
67	 * one.
68	 * This also means that we permit zcomp initialisation
69	 * with any compressing algorithm known to crypto api.
70	 */
71	return crypto_has_comp(comp, 0, 0) == 1;
72}
73
74/* show available compressors */
75ssize_t zcomp_available_show(const char *comp, char *buf)
76{
77	bool known_algorithm = false;
78	ssize_t sz = 0;
79	int i;
80
81	for (i = 0; i < ARRAY_SIZE(backends); i++) {
82		if (!strcmp(comp, backends[i])) {
83			known_algorithm = true;
84			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
85					"[%s] ", backends[i]);
86		} else {
87			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
88					"%s ", backends[i]);
89		}
90	}
91
92	/*
93	 * Out-of-tree module known to crypto api or a missing
94	 * entry in `backends'.
95	 */
96	if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
97		sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
98				"[%s] ", comp);
99
100	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
101	return sz;
102}
103
104struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
105{
106	local_lock(&comp->stream->lock);
107	return this_cpu_ptr(comp->stream);
108}
109
110void zcomp_stream_put(struct zcomp *comp)
111{
112	local_unlock(&comp->stream->lock);
113}
114
115int zcomp_compress(struct zcomp_strm *zstrm,
116		const void *src, unsigned int *dst_len)
117{
118	/*
119	 * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
120	 * because sometimes we can endup having a bigger compressed data
121	 * due to various reasons: for example compression algorithms tend
122	 * to add some padding to the compressed buffer. Speaking of padding,
123	 * comp algorithm `842' pads the compressed length to multiple of 8
124	 * and returns -ENOSP when the dst memory is not big enough, which
125	 * is not something that ZRAM wants to see. We can handle the
126	 * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
127	 * receive -ERRNO from the compressing backend we can't help it
128	 * anymore. To make `842' happy we need to tell the exact size of
129	 * the dst buffer, zram_drv will take care of the fact that
130	 * compressed buffer is too big.
131	 */
132	*dst_len = PAGE_SIZE * 2;
133
134	return crypto_comp_compress(zstrm->tfm,
135			src, PAGE_SIZE,
136			zstrm->buffer, dst_len);
137}
138
139int zcomp_decompress(struct zcomp_strm *zstrm,
140		const void *src, unsigned int src_len, void *dst)
141{
142	unsigned int dst_len = PAGE_SIZE;
143
144	return crypto_comp_decompress(zstrm->tfm,
145			src, src_len,
146			dst, &dst_len);
147}
148
149int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
150{
151	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
152	struct zcomp_strm *zstrm;
153	int ret;
154
155	zstrm = per_cpu_ptr(comp->stream, cpu);
156	local_lock_init(&zstrm->lock);
157
158	ret = zcomp_strm_init(zstrm, comp);
159	if (ret)
160		pr_err("Can't allocate a compression stream\n");
161	return ret;
162}
163
164int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
165{
166	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
167	struct zcomp_strm *zstrm;
168
169	zstrm = per_cpu_ptr(comp->stream, cpu);
170	zcomp_strm_free(zstrm);
171	return 0;
172}
173
174static int zcomp_init(struct zcomp *comp)
175{
176	int ret;
177
178	comp->stream = alloc_percpu(struct zcomp_strm);
179	if (!comp->stream)
180		return -ENOMEM;
181
182	ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
183	if (ret < 0)
184		goto cleanup;
185	return 0;
186
187cleanup:
188	free_percpu(comp->stream);
189	return ret;
190}
191
192void zcomp_destroy(struct zcomp *comp)
193{
194	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
195	free_percpu(comp->stream);
196	kfree(comp);
197}
198
199/*
200 * search available compressors for requested algorithm.
201 * allocate new zcomp and initialize it. return compressing
202 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
203 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
204 * case of allocation error, or any other error potentially
205 * returned by zcomp_init().
206 */
207struct zcomp *zcomp_create(const char *compress)
208{
209	struct zcomp *comp;
210	int error;
211
212	/*
213	 * Crypto API will execute /sbin/modprobe if the compression module
214	 * is not loaded yet. We must do it here, otherwise we are about to
215	 * call /sbin/modprobe under CPU hot-plug lock.
216	 */
217	if (!zcomp_available_algorithm(compress))
218		return ERR_PTR(-EINVAL);
219
220	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
221	if (!comp)
222		return ERR_PTR(-ENOMEM);
223
224	comp->name = compress;
225	error = zcomp_init(comp);
226	if (error) {
227		kfree(comp);
228		return ERR_PTR(error);
229	}
230	return comp;
231}
232