scsi: target: iscsi: switch to using the crc32c library

Now that the crc32c() library function directly takes advantage of
architecture-specific optimizations, it is unnecessary to go through the
crypto API. Just use crc32c(). This is much simpler, and it improves
performance due to eliminating the crypto API overhead.

Reviewed-by: Ard Biesheuvel <[e-mail]>
Reviewed-by: Martin K. Petersen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Eric Biggers <[e-mail]>

drivers/target/iscsi/Kconfig

···
 config ISCSI_TARGET
 	tristate "SCSI Target Mode Stack"
 	depends on INET
+	select CRC32
 	select CRYPTO
-	select CRYPTO_CRC32C
+	select CRYPTO_HASH
 	help
 	Say M to enable the SCSI target mode stack. A SCSI target mode stack
 	is software that makes local storage available over a storage network

drivers/target/iscsi/iscsi_target.c

···
  *
  ******************************************************************************/
 
-#include <crypto/hash.h>
+#include <linux/crc32c.h>
 #include <linux/string.h>
 #include <linux/kthread.h>
 #include <linux/completion.h>
···
 }
 EXPORT_SYMBOL(iscsit_aborted_task);
 
-static void iscsit_do_crypto_hash_buf(struct ahash_request *, const void *,
-				      u32, u32, const void *, void *);
+static u32 iscsit_crc_buf(const void *buf, u32 payload_length,
+			  u32 padding, const void *pad_bytes);
 static void iscsit_tx_thread_wait_for_tcp(struct iscsit_conn *);
 
 static int
···
 	if (conn->conn_ops->HeaderDigest) {
 		u32 *header_digest = (u32 *)&cmd->pdu[ISCSI_HDR_LEN];
 
-		iscsit_do_crypto_hash_buf(conn->conn_tx_hash, hdr,
-					  ISCSI_HDR_LEN, 0, NULL,
-					  header_digest);
+		*header_digest = iscsit_crc_buf(hdr, ISCSI_HDR_LEN, 0, NULL);
 
 		iov[0].iov_len += ISCSI_CRC_LEN;
 		tx_size += ISCSI_CRC_LEN;
···
 		}
 
 		if (conn->conn_ops->DataDigest) {
-			iscsit_do_crypto_hash_buf(conn->conn_tx_hash,
-						  data_buf, data_buf_len,
-						  padding, &cmd->pad_bytes,
-						  &cmd->data_crc);
-
+			cmd->data_crc = iscsit_crc_buf(data_buf, data_buf_len,
+						       padding,
+						       &cmd->pad_bytes);
 			iov[niov].iov_base = &cmd->data_crc;
 			iov[niov++].iov_len = ISCSI_CRC_LEN;
 			tx_size += ISCSI_CRC_LEN;
···
 static int iscsit_map_iovec(struct iscsit_cmd *cmd, struct kvec *iov, int nvec,
 			    u32 data_offset, u32 data_length);
 static void iscsit_unmap_iovec(struct iscsit_cmd *);
-static u32 iscsit_do_crypto_hash_sg(struct ahash_request *, struct iscsit_cmd *,
-				    u32, u32, u32, u8 *);
+static u32 iscsit_crc_sglist(const struct iscsit_cmd *cmd, u32 data_length,
+			     u32 padding, const u8 *pad_bytes);
 static int
 iscsit_xmit_datain_pdu(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
 		       const struct iscsi_datain *datain)
···
 	if (conn->conn_ops->HeaderDigest) {
 		u32 *header_digest = (u32 *)&cmd->pdu[ISCSI_HDR_LEN];
 
-		iscsit_do_crypto_hash_buf(conn->conn_tx_hash, cmd->pdu,
-					  ISCSI_HDR_LEN, 0, NULL,
-					  header_digest);
-
+		*header_digest = iscsit_crc_buf(cmd->pdu, ISCSI_HDR_LEN, 0,
+						NULL);
 		iov[0].iov_len += ISCSI_CRC_LEN;
 		tx_size += ISCSI_CRC_LEN;
 
···
 	}
 
 	if (conn->conn_ops->DataDigest) {
-		cmd->data_crc = iscsit_do_crypto_hash_sg(conn->conn_tx_hash,
-							 cmd, datain->offset,
-							 datain->length,
-							 cmd->padding,
-							 cmd->pad_bytes);
-
+		cmd->data_crc = iscsit_crc_sglist(cmd, datain->length,
+						  cmd->padding, cmd->pad_bytes);
 		iov[iov_count].iov_base	= &cmd->data_crc;
 		iov[iov_count++].iov_len = ISCSI_CRC_LEN;
 		tx_size += ISCSI_CRC_LEN;
···
 	return iscsit_get_immediate_data(cmd, hdr, dump_payload);
 }
 
-static u32 iscsit_do_crypto_hash_sg(
-	struct ahash_request *hash,
-	struct iscsit_cmd *cmd,
-	u32 data_offset,
-	u32 data_length,
-	u32 padding,
-	u8 *pad_bytes)
+static u32 iscsit_crc_sglist(const struct iscsit_cmd *cmd, u32 data_length,
+			     u32 padding, const u8 *pad_bytes)
 {
-	u32 data_crc;
-	struct scatterlist *sg;
-	unsigned int page_off;
-
-	crypto_ahash_init(hash);
-
-	sg = cmd->first_data_sg;
-	page_off = cmd->first_data_sg_off;
-
-	if (data_length && page_off) {
-		struct scatterlist first_sg;
-		u32 len = min_t(u32, data_length, sg->length - page_off);
-
-		sg_init_table(&first_sg, 1);
-		sg_set_page(&first_sg, sg_page(sg), len, sg->offset + page_off);
-
-		ahash_request_set_crypt(hash, &first_sg, NULL, len);
-		crypto_ahash_update(hash);
-
-		data_length -= len;
-		sg = sg_next(sg);
-	}
+	struct scatterlist *sg = cmd->first_data_sg;
+	unsigned int page_off = cmd->first_data_sg_off;
+	u32 crc = ~0;
 
 	while (data_length) {
-		u32 cur_len = min_t(u32, data_length, sg->length);
+		u32 cur_len = min_t(u32, data_length, sg->length - page_off);
+		const void *virt;
 
-		ahash_request_set_crypt(hash, sg, NULL, cur_len);
-		crypto_ahash_update(hash);
+		virt = kmap_local_page(sg_page(sg)) + sg->offset + page_off;
+		crc = crc32c(crc, virt, cur_len);
+		kunmap_local(virt);
 
-		data_length -= cur_len;
 		/* iscsit_map_iovec has already checked for invalid sg pointers */
 		sg = sg_next(sg);
+
+		page_off = 0;
+		data_length -= cur_len;
 	}
 
-	if (padding) {
-		struct scatterlist pad_sg;
+	if (padding)
+		crc = crc32c(crc, pad_bytes, padding);
 
-		sg_init_one(&pad_sg, pad_bytes, padding);
-		ahash_request_set_crypt(hash, &pad_sg, (u8 *)&data_crc,
-					padding);
-		crypto_ahash_finup(hash);
-	} else {
-		ahash_request_set_crypt(hash, NULL, (u8 *)&data_crc, 0);
-		crypto_ahash_final(hash);
-	}
-
-	return data_crc;
+	return ~crc;
 }
 
-static void iscsit_do_crypto_hash_buf(struct ahash_request *hash,
-	const void *buf, u32 payload_length, u32 padding,
-	const void *pad_bytes, void *data_crc)
+static u32 iscsit_crc_buf(const void *buf, u32 payload_length,
+			  u32 padding, const void *pad_bytes)
 {
-	struct scatterlist sg[2];
+	u32 crc = ~0;
 
-	sg_init_table(sg, ARRAY_SIZE(sg));
-	sg_set_buf(sg, buf, payload_length);
+	crc = crc32c(crc, buf, payload_length);
+
 	if (padding)
-		sg_set_buf(sg + 1, pad_bytes, padding);
+		crc = crc32c(crc, pad_bytes, padding);
 
-	ahash_request_set_crypt(hash, sg, data_crc, payload_length + padding);
-
-	crypto_ahash_digest(hash);
+	return ~crc;
 }
 
 int
···
 	if (conn->conn_ops->DataDigest) {
 		u32 data_crc;
 
-		data_crc = iscsit_do_crypto_hash_sg(conn->conn_rx_hash, cmd,
-						    be32_to_cpu(hdr->offset),
-						    payload_length, padding,
-						    cmd->pad_bytes);
-
+		data_crc = iscsit_crc_sglist(cmd, payload_length, padding,
+					     cmd->pad_bytes);
 		if (checksum != data_crc) {
 			pr_err("ITT: 0x%08x, Offset: %u, Length: %u,"
 				" DataSN: 0x%08x, CRC32C DataDigest 0x%08x"
···
 		}
 
 		if (conn->conn_ops->DataDigest) {
-			iscsit_do_crypto_hash_buf(conn->conn_rx_hash, ping_data,
-						  payload_length, padding,
-						  cmd->pad_bytes, &data_crc);
-
+			data_crc = iscsit_crc_buf(ping_data, payload_length,
+						  padding, cmd->pad_bytes);
 			if (checksum != data_crc) {
 				pr_err("Ping data CRC32C DataDigest"
 				" 0x%08x does not match computed 0x%08x\n",
···
 			goto reject;
 
 		if (conn->conn_ops->DataDigest) {
-			iscsit_do_crypto_hash_buf(conn->conn_rx_hash,
-						  text_in, rx_size, 0, NULL,
-						  &data_crc);
-
+			data_crc = iscsit_crc_buf(text_in, rx_size, 0, NULL);
 			if (checksum != data_crc) {
 				pr_err("Text data CRC32C DataDigest"
 					" 0x%08x does not match computed"
···
 	if (conn->conn_ops->DataDigest) {
 		u32 data_crc;
 
-		data_crc = iscsit_do_crypto_hash_sg(conn->conn_rx_hash, cmd,
-						    cmd->write_data_done, length, padding,
-						    cmd->pad_bytes);
-
+		data_crc = iscsit_crc_sglist(cmd, length, padding,
+					     cmd->pad_bytes);
 		if (checksum != data_crc) {
 			pr_err("ImmediateData CRC32C DataDigest 0x%08x"
 				" does not match computed 0x%08x\n", checksum,
···
 				break;
 			}
 
-			iscsit_do_crypto_hash_buf(conn->conn_rx_hash, buffer,
-						  ISCSI_HDR_LEN, 0, NULL,
-						  &checksum);
-
+			checksum = iscsit_crc_buf(buffer, ISCSI_HDR_LEN, 0,
+						  NULL);
 			if (digest != checksum) {
 				pr_err("HeaderDigest CRC32C failed,"
 					" received 0x%08x, computed 0x%08x\n",
···
 	 * must wait until they have completed.
 	 */
 	iscsit_check_conn_usage_count(conn);
-
-	ahash_request_free(conn->conn_tx_hash);
-	if (conn->conn_rx_hash) {
-		struct crypto_ahash *tfm;
-
-		tfm = crypto_ahash_reqtfm(conn->conn_rx_hash);
-		ahash_request_free(conn->conn_rx_hash);
-		crypto_free_ahash(tfm);
-	}
 
 	if (conn->sock)
 		sock_release(conn->sock);

drivers/target/iscsi/iscsi_target_login.c

···
  *
  ******************************************************************************/
 
-#include <crypto/hash.h>
 #include <linux/module.h>
 #include <linux/string.h>
 #include <linux/kthread.h>
···
 out_login:
 	kfree(login);
 	return NULL;
-}
-
-/*
- * Used by iscsi_target_nego.c:iscsi_target_locate_portal() to setup
- * per struct iscsit_conn libcrypto contexts for crc32c and crc32-intel
- */
-int iscsi_login_setup_crypto(struct iscsit_conn *conn)
-{
-	struct crypto_ahash *tfm;
-
-	/*
-	 * Setup slicing by CRC32C algorithm for RX and TX libcrypto contexts
-	 * which will default to crc32c_intel.ko for cpu_has_xmm4_2, or fallback
-	 * to software 1x8 byte slicing from crc32c.ko
-	 */
-	tfm = crypto_alloc_ahash("crc32c", 0, CRYPTO_ALG_ASYNC);
-	if (IS_ERR(tfm)) {
-		pr_err("crypto_alloc_ahash() failed\n");
-		return -ENOMEM;
-	}
-
-	conn->conn_rx_hash = ahash_request_alloc(tfm, GFP_KERNEL);
-	if (!conn->conn_rx_hash) {
-		pr_err("ahash_request_alloc() failed for conn_rx_hash\n");
-		crypto_free_ahash(tfm);
-		return -ENOMEM;
-	}
-	ahash_request_set_callback(conn->conn_rx_hash, 0, NULL, NULL);
-
-	conn->conn_tx_hash = ahash_request_alloc(tfm, GFP_KERNEL);
-	if (!conn->conn_tx_hash) {
-		pr_err("ahash_request_alloc() failed for conn_tx_hash\n");
-		ahash_request_free(conn->conn_rx_hash);
-		conn->conn_rx_hash = NULL;
-		crypto_free_ahash(tfm);
-		return -ENOMEM;
-	}
-	ahash_request_set_callback(conn->conn_tx_hash, 0, NULL, NULL);
-
-	return 0;
 }
 
 static int iscsi_login_check_initiator_version(
···
 		} else
 			spin_unlock_bh(&conn->sess->conn_lock);
 		iscsit_dec_session_usage_count(conn->sess);
-	}
-
-	ahash_request_free(conn->conn_tx_hash);
-	if (conn->conn_rx_hash) {
-		struct crypto_ahash *tfm;
-
-		tfm = crypto_ahash_reqtfm(conn->conn_rx_hash);
-		ahash_request_free(conn->conn_rx_hash);
-		crypto_free_ahash(tfm);
 	}
 
 	if (conn->param_list) {

drivers/target/iscsi/iscsi_target_login.h

···
 struct iscsi_np;
 struct sockaddr_storage;
 
-extern int iscsi_login_setup_crypto(struct iscsit_conn *);
 extern int iscsi_check_for_session_reinstatement(struct iscsit_conn *);
 extern int iscsi_login_post_auth_non_zero_tsih(struct iscsit_conn *, u16, u32);
 extern int iscsit_setup_np(struct iscsi_np *,

drivers/target/iscsi/iscsi_target_nego.c

···
 			goto get_target;
 
 		sess->sess_ops->SessionType = 1;
-		/*
-		 * Setup crc32c modules from libcrypto
-		 */
-		if (iscsi_login_setup_crypto(conn) < 0) {
-			pr_err("iscsi_login_setup_crypto() failed\n");
-			ret = -1;
-			goto out;
-		}
+
 		/*
 		 * Serialize access across the discovery struct iscsi_portal_group to
 		 * process login attempt.
···
 	}
 	conn->tpg_np = tpg_np;
 	pr_debug("Located Portal Group Object: %hu\n", conn->tpg->tpgt);
-	/*
-	 * Setup crc32c modules from libcrypto
-	 */
-	if (iscsi_login_setup_crypto(conn) < 0) {
-		pr_err("iscsi_login_setup_crypto() failed\n");
-		kref_put(&tpg_np->tpg_np_kref, iscsit_login_kref_put);
-		iscsit_put_tiqn_for_login(tiqn);
-		conn->tpg = NULL;
-		ret = -1;
-		goto out;
-	}
+
 	/*
 	 * Serialize access across the struct iscsi_portal_group to
 	 * process login attempt.

include/target/iscsi/iscsi_target_core.h

···
 	spinlock_t		state_lock;
 	spinlock_t		login_timer_lock;
 	spinlock_t		login_worker_lock;
-	/* libcrypto RX and TX contexts for crc32c */
-	struct ahash_request	*conn_rx_hash;
-	struct ahash_request	*conn_tx_hash;
 	/* Used for scheduling TX and RX connection kthreads */
 	cpumask_var_t		conn_cpumask;
 	cpumask_var_t		allowed_cpumask;