crypto: add rocksoft 64b crc guard tag framework

Hardware specific features may be able to calculate a crc64, so provide
a framework for drivers to register their implementation. If nothing is
registered, fallback to the generic table lookup implementation. The
implementation is modeled after the crct10dif equivalent.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20220303201312.3255347-7-kbusch@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 126 insertions, 0 deletions

diff --git a/lib/crc64-rocksoft.c b/lib/crc64-rocksoft.c
new file mode 100644
index 000000000000..fc9ae0da5df7
--- /dev/null
+++ b/lib/crc64-rocksoft.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/crc64.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <crypto/hash.h>
+#include <crypto/algapi.h>
+#include <linux/static_key.h>
+#include <linux/notifier.h>
+
+static struct crypto_shash __rcu *crc64_rocksoft_tfm;
+static DEFINE_STATIC_KEY_TRUE(crc64_rocksoft_fallback);
+static DEFINE_MUTEX(crc64_rocksoft_mutex);
+static struct work_struct crc64_rocksoft_rehash_work;
+
+static int crc64_rocksoft_notify(struct notifier_block *self, unsigned long val, void *data)
+{
+	struct crypto_alg *alg = data;
+
+	if (val != CRYPTO_MSG_ALG_LOADED ||
+	    strcmp(alg->cra_name, CRC64_ROCKSOFT_STRING))
+		return NOTIFY_DONE;
+
+	schedule_work(&crc64_rocksoft_rehash_work);
+	return NOTIFY_OK;
+}
+
+static void crc64_rocksoft_rehash(struct work_struct *work)
+{
+	struct crypto_shash *new, *old;
+
+	mutex_lock(&crc64_rocksoft_mutex);
+	old = rcu_dereference_protected(crc64_rocksoft_tfm,
+					lockdep_is_held(&crc64_rocksoft_mutex));
+	new = crypto_alloc_shash(CRC64_ROCKSOFT_STRING, 0, 0);
+	if (IS_ERR(new)) {
+		mutex_unlock(&crc64_rocksoft_mutex);
+		return;
+	}
+	rcu_assign_pointer(crc64_rocksoft_tfm, new);
+	mutex_unlock(&crc64_rocksoft_mutex);
+
+	if (old) {
+		synchronize_rcu();
+		crypto_free_shash(old);
+	} else {
+		static_branch_disable(&crc64_rocksoft_fallback);
+	}
+}
+
+static struct notifier_block crc64_rocksoft_nb = {
+	.notifier_call = crc64_rocksoft_notify,
+};
+
+u64 crc64_rocksoft_update(u64 crc, const unsigned char *buffer, size_t len)
+{
+	struct {
+		struct shash_desc shash;
+		u64 crc;
+	} desc;
+	int err;
+
+	if (static_branch_unlikely(&crc64_rocksoft_fallback))
+		return crc64_rocksoft_generic(crc, buffer, len);
+
+	rcu_read_lock();
+	desc.shash.tfm = rcu_dereference(crc64_rocksoft_tfm);
+	desc.crc = crc;
+	err = crypto_shash_update(&desc.shash, buffer, len);
+	rcu_read_unlock();
+
+	BUG_ON(err);
+
+	return desc.crc;
+}
+EXPORT_SYMBOL_GPL(crc64_rocksoft_update);
+
+u64 crc64_rocksoft(const unsigned char *buffer, size_t len)
+{
+	return crc64_rocksoft_update(0, buffer, len);
+}
+EXPORT_SYMBOL_GPL(crc64_rocksoft);
+
+static int __init crc64_rocksoft_mod_init(void)
+{
+	INIT_WORK(&crc64_rocksoft_rehash_work, crc64_rocksoft_rehash);
+	crypto_register_notifier(&crc64_rocksoft_nb);
+	crc64_rocksoft_rehash(&crc64_rocksoft_rehash_work);
+	return 0;
+}
+
+static void __exit crc64_rocksoft_mod_fini(void)
+{
+	crypto_unregister_notifier(&crc64_rocksoft_nb);
+	cancel_work_sync(&crc64_rocksoft_rehash_work);
+	crypto_free_shash(rcu_dereference_protected(crc64_rocksoft_tfm, 1));
+}
+
+module_init(crc64_rocksoft_mod_init);
+module_exit(crc64_rocksoft_mod_fini);
+
+static int crc64_rocksoft_transform_show(char *buffer, const struct kernel_param *kp)
+{
+	struct crypto_shash *tfm;
+	int len;
+
+	if (static_branch_unlikely(&crc64_rocksoft_fallback))
+		return sprintf(buffer, "fallback\n");
+
+	rcu_read_lock();
+	tfm = rcu_dereference(crc64_rocksoft_tfm);
+	len = snprintf(buffer, PAGE_SIZE, "%s\n",
+		       crypto_shash_driver_name(tfm));
+	rcu_read_unlock();
+
+	return len;
+}
+
+module_param_call(transform, NULL, crc64_rocksoft_transform_show, NULL, 0444);
+
+MODULE_AUTHOR("Keith Busch <kbusch@kernel.org>");
+MODULE_DESCRIPTION("Rocksoft model CRC64 calculation (library API)");
+MODULE_LICENSE("GPL");
+MODULE_SOFTDEP("pre: crc64");