1 files changed, 231 insertions, 0 deletions
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
new file mode 100644
index 000000000..b08650417
--- /dev/null
+++ b/drivers/block/zram/zcomp.c
@@ -0,0 +1,231 @@
+// 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[] = {
+	"lzo",
+	"lzo-rle",
+#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 *compress)
+{
+	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(compress))
+		return ERR_PTR(-EINVAL);
+
+	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
+	if (!comp)
+		return ERR_PTR(-ENOMEM);
+
+	comp->name = compress;
+	error = zcomp_init(comp);
+	if (error) {
+		kfree(comp);
+		return ERR_PTR(error);
+	}
+	return comp;
+}