arch/powerpc/crypto/aes-spe-glue.c - linux/kernel/git/dhowells/linux-fs - Git at Google


            
            // SPDX-License-Identifier: GPL-2.0-or-later

            
            /*

            
             * Glue code for AES implementation for SPE instructions (PPC)

            
             *

            
             * Based on generic implementation. The assembler module takes care

            
             * about the SPE registers so it can run from interrupt context.

            
             *

            
             * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>

            
             */


            #include <crypto/aes.h>

            
            #include <linux/minmax.h>

            
            #include <linux/module.h>

            
            #include <linux/init.h>

            
            #include <linux/types.h>

            
            #include <linux/errno.h>

            
            #include <linux/crypto.h>

            
            #include <asm/byteorder.h>

            
            #include <asm/switch_to.h>

            
            #include <crypto/algapi.h>

            
            #include <crypto/internal/skcipher.h>

            
            #include <crypto/xts.h>

            
            #include <crypto/gf128mul.h>

            
            #include <crypto/scatterwalk.h>


            /*

            
             * MAX_BYTES defines the number of bytes that are allowed to be processed

            
             * between preempt_disable() and preempt_enable(). e500 cores can issue two

            
             * instructions per clock cycle using one 32/64 bit unit (SU1) and one 32

            
             * bit unit (SU2). One of these can be a memory access that is executed via

            
             * a single load and store unit (LSU). XTS-AES-256 takes ~780 operations per

            
             * 16 byte block or 25 cycles per byte. Thus 768 bytes of input data

            
             * will need an estimated maximum of 20,000 cycles. Headroom for cache misses

            
             * included. Even with the low end model clocked at 667 MHz this equals to a

            
             * critical time window of less than 30us. The value has been chosen to

            
             * process a 512 byte disk block in one or a large 1400 bytes IPsec network

            
             * packet in two runs.

            
             *

            
             */

            
            #define MAX_BYTES 768


            struct ppc_aes_ctx {

            
            	u32 key_enc[AES_MAX_KEYLENGTH_U32];

            
            	u32 key_dec[AES_MAX_KEYLENGTH_U32];

            
            	u32 rounds;

            
            };


            struct ppc_xts_ctx {

            
            	u32 key_enc[AES_MAX_KEYLENGTH_U32];

            
            	u32 key_dec[AES_MAX_KEYLENGTH_U32];

            
            	u32 key_twk[AES_MAX_KEYLENGTH_U32];

            
            	u32 rounds;

            
            };


            static void spe_begin(void)

            
            {

            
            	/* disable preemption and save users SPE registers if required */

            
            	preempt_disable();

            
            	enable_kernel_spe();

            
            }


            static void spe_end(void)

            
            {

            
            	disable_kernel_spe();

            
            	/* reenable preemption */

            
            	preempt_enable();

            
            }


            static int ppc_aes_setkey_skcipher(struct crypto_skcipher *tfm,

            
            				   const u8 *in_key, unsigned int key_len)

            
            {

            
            	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);


            	switch (key_len) {

            
            	case AES_KEYSIZE_128:

            
            		ctx->rounds = 4;

            
            		ppc_expand_key_128(ctx->key_enc, in_key);

            
            		break;

            
            	case AES_KEYSIZE_192:

            
            		ctx->rounds = 5;

            
            		ppc_expand_key_192(ctx->key_enc, in_key);

            
            		break;

            
            	case AES_KEYSIZE_256:

            
            		ctx->rounds = 6;

            
            		ppc_expand_key_256(ctx->key_enc, in_key);

            
            		break;

            
            	default:

            
            		return -EINVAL;

            
            	}


            	ppc_generate_decrypt_key(ctx->key_dec, ctx->key_enc, key_len);


            	return 0;

            
            }


            static int ppc_xts_setkey(struct crypto_skcipher *tfm, const u8 *in_key,

            
            		   unsigned int key_len)

            
            {

            
            	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);

            
            	int err;


            	err = xts_verify_key(tfm, in_key, key_len);

            
            	if (err)

            
            		return err;


            	key_len >>= 1;


            	switch (key_len) {

            
            	case AES_KEYSIZE_128:

            
            		ctx->rounds = 4;

            
            		ppc_expand_key_128(ctx->key_enc, in_key);

            
            		ppc_expand_key_128(ctx->key_twk, in_key + AES_KEYSIZE_128);

            
            		break;

            
            	case AES_KEYSIZE_192:

            
            		ctx->rounds = 5;

            
            		ppc_expand_key_192(ctx->key_enc, in_key);

            
            		ppc_expand_key_192(ctx->key_twk, in_key + AES_KEYSIZE_192);

            
            		break;

            
            	case AES_KEYSIZE_256:

            
            		ctx->rounds = 6;

            
            		ppc_expand_key_256(ctx->key_enc, in_key);

            
            		ppc_expand_key_256(ctx->key_twk, in_key + AES_KEYSIZE_256);

            
            		break;

            
            	default:

            
            		return -EINVAL;

            
            	}


            	ppc_generate_decrypt_key(ctx->key_dec, ctx->key_enc, key_len);


            	return 0;

            
            }


            static int ppc_ecb_crypt(struct skcipher_request *req, bool enc)

            
            {

            
            	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

            
            	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);

            
            	struct skcipher_walk walk;

            
            	unsigned int nbytes;

            
            	int err;


            	err = skcipher_walk_virt(&walk, req, false);


            	while ((nbytes = walk.nbytes) != 0) {

            
            		nbytes = min(nbytes, MAX_BYTES);

            
            		nbytes = round_down(nbytes, AES_BLOCK_SIZE);


            		spe_begin();

            
            		if (enc)

            
            			ppc_encrypt_ecb(walk.dst.virt.addr, walk.src.virt.addr,

            
            					ctx->key_enc, ctx->rounds, nbytes);

            
            		else

            
            			ppc_decrypt_ecb(walk.dst.virt.addr, walk.src.virt.addr,

            
            					ctx->key_dec, ctx->rounds, nbytes);

            
            		spe_end();


            		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);

            
            	}


            	return err;

            
            }


            static int ppc_ecb_encrypt(struct skcipher_request *req)

            
            {

            
            	return ppc_ecb_crypt(req, true);

            
            }


            static int ppc_ecb_decrypt(struct skcipher_request *req)

            
            {

            
            	return ppc_ecb_crypt(req, false);

            
            }


            static int ppc_cbc_crypt(struct skcipher_request *req, bool enc)

            
            {

            
            	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

            
            	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);

            
            	struct skcipher_walk walk;

            
            	unsigned int nbytes;

            
            	int err;


            	err = skcipher_walk_virt(&walk, req, false);


            	while ((nbytes = walk.nbytes) != 0) {

            
            		nbytes = min(nbytes, MAX_BYTES);

            
            		nbytes = round_down(nbytes, AES_BLOCK_SIZE);


            		spe_begin();

            
            		if (enc)

            
            			ppc_encrypt_cbc(walk.dst.virt.addr, walk.src.virt.addr,

            
            					ctx->key_enc, ctx->rounds, nbytes,

            
            					walk.iv);

            
            		else

            
            			ppc_decrypt_cbc(walk.dst.virt.addr, walk.src.virt.addr,

            
            					ctx->key_dec, ctx->rounds, nbytes,

            
            					walk.iv);

            
            		spe_end();


            		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);

            
            	}


            	return err;

            
            }


            static int ppc_cbc_encrypt(struct skcipher_request *req)

            
            {

            
            	return ppc_cbc_crypt(req, true);

            
            }


            static int ppc_cbc_decrypt(struct skcipher_request *req)

            
            {

            
            	return ppc_cbc_crypt(req, false);

            
            }


            static int ppc_ctr_crypt(struct skcipher_request *req)

            
            {

            
            	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

            
            	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);

            
            	struct skcipher_walk walk;

            
            	unsigned int nbytes;

            
            	int err;


            	err = skcipher_walk_virt(&walk, req, false);


            	while ((nbytes = walk.nbytes) != 0) {

            
            		nbytes = min(nbytes, MAX_BYTES);

            
            		if (nbytes < walk.total)

            
            			nbytes = round_down(nbytes, AES_BLOCK_SIZE);


            		spe_begin();

            
            		ppc_crypt_ctr(walk.dst.virt.addr, walk.src.virt.addr,

            
            			      ctx->key_enc, ctx->rounds, nbytes, walk.iv);

            
            		spe_end();


            		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);

            
            	}


            	return err;

            
            }


            static int ppc_xts_crypt(struct skcipher_request *req, bool enc)

            
            {

            
            	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

            
            	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);

            
            	struct skcipher_walk walk;

            
            	unsigned int nbytes;

            
            	int err;

            
            	u32 *twk;


            	err = skcipher_walk_virt(&walk, req, false);

            
            	twk = ctx->key_twk;


            	while ((nbytes = walk.nbytes) != 0) {

            
            		nbytes = min(nbytes, MAX_BYTES);

            
            		nbytes = round_down(nbytes, AES_BLOCK_SIZE);


            		spe_begin();

            
            		if (enc)

            
            			ppc_encrypt_xts(walk.dst.virt.addr, walk.src.virt.addr,

            
            					ctx->key_enc, ctx->rounds, nbytes,

            
            					walk.iv, twk);

            
            		else

            
            			ppc_decrypt_xts(walk.dst.virt.addr, walk.src.virt.addr,

            
            					ctx->key_dec, ctx->rounds, nbytes,

            
            					walk.iv, twk);

            
            		spe_end();


            		twk = NULL;

            
            		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);

            
            	}


            	return err;

            
            }


            static int ppc_xts_encrypt(struct skcipher_request *req)

            
            {

            
            	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

            
            	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);

            
            	int tail = req->cryptlen % AES_BLOCK_SIZE;

            
            	int offset = req->cryptlen - tail - AES_BLOCK_SIZE;

            
            	struct skcipher_request subreq;

            
            	u8 b[2][AES_BLOCK_SIZE];

            
            	int err;


            	if (req->cryptlen < AES_BLOCK_SIZE)

            
            		return -EINVAL;


            	if (tail) {

            
            		subreq = *req;

            
            		skcipher_request_set_crypt(&subreq, req->src, req->dst,

            
            					   req->cryptlen - tail, req->iv);

            
            		req = &subreq;

            
            	}


            	err = ppc_xts_crypt(req, true);

            
            	if (err || !tail)

            
            		return err;


            	scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE, 0);

            
            	memcpy(b[1], b[0], tail);

            
            	scatterwalk_map_and_copy(b[0], req->src, offset + AES_BLOCK_SIZE, tail, 0);


            	spe_begin();

            
            	ppc_encrypt_xts(b[0], b[0], ctx->key_enc, ctx->rounds, AES_BLOCK_SIZE,

            
            			req->iv, NULL);

            
            	spe_end();


            	scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE + tail, 1);


            	return 0;

            
            }


            static int ppc_xts_decrypt(struct skcipher_request *req)

            
            {

            
            	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

            
            	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);

            
            	int tail = req->cryptlen % AES_BLOCK_SIZE;

            
            	int offset = req->cryptlen - tail - AES_BLOCK_SIZE;

            
            	struct skcipher_request subreq;

            
            	u8 b[3][AES_BLOCK_SIZE];

            
            	le128 twk;

            
            	int err;


            	if (req->cryptlen < AES_BLOCK_SIZE)

            
            		return -EINVAL;


            	if (tail) {

            
            		subreq = *req;

            
            		skcipher_request_set_crypt(&subreq, req->src, req->dst,

            
            					   offset, req->iv);

            
            		req = &subreq;

            
            	}


            	err = ppc_xts_crypt(req, false);

            
            	if (err || !tail)

            
            		return err;


            	scatterwalk_map_and_copy(b[1], req->src, offset, AES_BLOCK_SIZE + tail, 0);


            	spe_begin();

            
            	if (!offset)

            
            		ppc_encrypt_ecb(req->iv, req->iv, ctx->key_twk, ctx->rounds,

            
            				AES_BLOCK_SIZE);


            	gf128mul_x_ble(&twk, (le128 *)req->iv);


            	ppc_decrypt_xts(b[1], b[1], ctx->key_dec, ctx->rounds, AES_BLOCK_SIZE,

            
            			(u8 *)&twk, NULL);

            
            	memcpy(b[0], b[2], tail);

            
            	memcpy(b[0] + tail, b[1] + tail, AES_BLOCK_SIZE - tail);

            
            	ppc_decrypt_xts(b[0], b[0], ctx->key_dec, ctx->rounds, AES_BLOCK_SIZE,

            
            			req->iv, NULL);

            
            	spe_end();


            	scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE + tail, 1);


            	return 0;

            
            }


            /*

            
             * Algorithm definitions. Disabling alignment (cra_alignmask=0) was chosen

            
             * because the e500 platform can handle unaligned reads/writes very efficiently.

            
             * This improves IPsec thoughput by another few percent. Additionally we assume

            
             * that AES context is always aligned to at least 8 bytes because it is created

            
             * with kmalloc() in the crypto infrastructure

            
             */


            static struct skcipher_alg aes_skcipher_algs[] = {

            
            	{

            
            		.base.cra_name		=	"ecb(aes)",

            
            		.base.cra_driver_name	=	"ecb-ppc-spe",

            
            		.base.cra_priority	=	300,

            
            		.base.cra_blocksize	=	AES_BLOCK_SIZE,

            
            		.base.cra_ctxsize	=	sizeof(struct ppc_aes_ctx),

            
            		.base.cra_module	=	THIS_MODULE,

            
            		.min_keysize		=	AES_MIN_KEY_SIZE,

            
            		.max_keysize		=	AES_MAX_KEY_SIZE,

            
            		.setkey			=	ppc_aes_setkey_skcipher,

            
            		.encrypt		=	ppc_ecb_encrypt,

            
            		.decrypt		=	ppc_ecb_decrypt,

            
            	}, {

            
            		.base.cra_name		=	"cbc(aes)",

            
            		.base.cra_driver_name	=	"cbc-ppc-spe",

            
            		.base.cra_priority	=	300,

            
            		.base.cra_blocksize	=	AES_BLOCK_SIZE,

            
            		.base.cra_ctxsize	=	sizeof(struct ppc_aes_ctx),

            
            		.base.cra_module	=	THIS_MODULE,

            
            		.min_keysize		=	AES_MIN_KEY_SIZE,

            
            		.max_keysize		=	AES_MAX_KEY_SIZE,

            
            		.ivsize			=	AES_BLOCK_SIZE,

            
            		.setkey			=	ppc_aes_setkey_skcipher,

            
            		.encrypt		=	ppc_cbc_encrypt,

            
            		.decrypt		=	ppc_cbc_decrypt,

            
            	}, {

            
            		.base.cra_name		=	"ctr(aes)",

            
            		.base.cra_driver_name	=	"ctr-ppc-spe",

            
            		.base.cra_priority	=	300,

            
            		.base.cra_blocksize	=	1,

            
            		.base.cra_ctxsize	=	sizeof(struct ppc_aes_ctx),

            
            		.base.cra_module	=	THIS_MODULE,

            
            		.min_keysize		=	AES_MIN_KEY_SIZE,

            
            		.max_keysize		=	AES_MAX_KEY_SIZE,

            
            		.ivsize			=	AES_BLOCK_SIZE,

            
            		.setkey			=	ppc_aes_setkey_skcipher,

            
            		.encrypt		=	ppc_ctr_crypt,

            
            		.decrypt		=	ppc_ctr_crypt,

            
            		.chunksize		=	AES_BLOCK_SIZE,

            
            	}, {

            
            		.base.cra_name		=	"xts(aes)",

            
            		.base.cra_driver_name	=	"xts-ppc-spe",

            
            		.base.cra_priority	=	300,

            
            		.base.cra_blocksize	=	AES_BLOCK_SIZE,

            
            		.base.cra_ctxsize	=	sizeof(struct ppc_xts_ctx),

            
            		.base.cra_module	=	THIS_MODULE,

            
            		.min_keysize		=	AES_MIN_KEY_SIZE * 2,

            
            		.max_keysize		=	AES_MAX_KEY_SIZE * 2,

            
            		.ivsize			=	AES_BLOCK_SIZE,

            
            		.setkey			=	ppc_xts_setkey,

            
            		.encrypt		=	ppc_xts_encrypt,

            
            		.decrypt		=	ppc_xts_decrypt,

            
            	}

            
            };


            static int __init ppc_aes_mod_init(void)

            
            {

            
            	return crypto_register_skciphers(aes_skcipher_algs,

            
            					 ARRAY_SIZE(aes_skcipher_algs));

            
            }


            static void __exit ppc_aes_mod_fini(void)

            
            {

            
            	crypto_unregister_skciphers(aes_skcipher_algs,

            
            				    ARRAY_SIZE(aes_skcipher_algs));

            
            }


            module_init(ppc_aes_mod_init);

            
            module_exit(ppc_aes_mod_fini);


            MODULE_LICENSE("GPL");

            
            MODULE_DESCRIPTION("AES-ECB/CBC/CTR/XTS, SPE optimized");


            MODULE_ALIAS_CRYPTO("aes");

            
            MODULE_ALIAS_CRYPTO("ecb(aes)");

            
            MODULE_ALIAS_CRYPTO("cbc(aes)");

            
            MODULE_ALIAS_CRYPTO("ctr(aes)");

            
            MODULE_ALIAS_CRYPTO("xts(aes)");

            
            MODULE_ALIAS_CRYPTO("aes-ppc-spe");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Glue code for AES implementation for SPE instructions (PPC)
	*
	* Based on generic implementation. The assembler module takes care
	* about the SPE registers so it can run from interrupt context.
	*
	* Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
	*/

	#include <crypto/aes.h>
	#include <linux/minmax.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/types.h>
	#include <linux/errno.h>
	#include <linux/crypto.h>
	#include <asm/byteorder.h>
	#include <asm/switch_to.h>
	#include <crypto/algapi.h>
	#include <crypto/internal/skcipher.h>
	#include <crypto/xts.h>
	#include <crypto/gf128mul.h>
	#include <crypto/scatterwalk.h>

	/*
	* MAX_BYTES defines the number of bytes that are allowed to be processed
	* between preempt_disable() and preempt_enable(). e500 cores can issue two
	* instructions per clock cycle using one 32/64 bit unit (SU1) and one 32
	* bit unit (SU2). One of these can be a memory access that is executed via
	* a single load and store unit (LSU). XTS-AES-256 takes ~780 operations per
	* 16 byte block or 25 cycles per byte. Thus 768 bytes of input data
	* will need an estimated maximum of 20,000 cycles. Headroom for cache misses
	* included. Even with the low end model clocked at 667 MHz this equals to a
	* critical time window of less than 30us. The value has been chosen to
	* process a 512 byte disk block in one or a large 1400 bytes IPsec network
	* packet in two runs.
	*
	*/
	#define MAX_BYTES 768

	struct ppc_aes_ctx {
	u32 key_enc[AES_MAX_KEYLENGTH_U32];
	u32 key_dec[AES_MAX_KEYLENGTH_U32];
	u32 rounds;
	};

	struct ppc_xts_ctx {
	u32 key_enc[AES_MAX_KEYLENGTH_U32];
	u32 key_dec[AES_MAX_KEYLENGTH_U32];
	u32 key_twk[AES_MAX_KEYLENGTH_U32];
	u32 rounds;
	};

	static void spe_begin(void)
	{
	/* disable preemption and save users SPE registers if required */
	preempt_disable();
	enable_kernel_spe();
	}

	static void spe_end(void)
	{
	disable_kernel_spe();
	/* reenable preemption */
	preempt_enable();
	}

	static int ppc_aes_setkey_skcipher(struct crypto_skcipher *tfm,
	const u8 *in_key, unsigned int key_len)
	{
	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);

	switch (key_len) {
	case AES_KEYSIZE_128:
	ctx->rounds = 4;
	ppc_expand_key_128(ctx->key_enc, in_key);
	break;
	case AES_KEYSIZE_192:
	ctx->rounds = 5;
	ppc_expand_key_192(ctx->key_enc, in_key);
	break;
	case AES_KEYSIZE_256:
	ctx->rounds = 6;
	ppc_expand_key_256(ctx->key_enc, in_key);
	break;
	default:
	return -EINVAL;
	}

	ppc_generate_decrypt_key(ctx->key_dec, ctx->key_enc, key_len);

	return 0;
	}

	static int ppc_xts_setkey(struct crypto_skcipher tfm, const u8 in_key,
	unsigned int key_len)
	{
	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
	int err;

	err = xts_verify_key(tfm, in_key, key_len);
	if (err)
	return err;

	key_len >>= 1;

	switch (key_len) {
	case AES_KEYSIZE_128:
	ctx->rounds = 4;
	ppc_expand_key_128(ctx->key_enc, in_key);
	ppc_expand_key_128(ctx->key_twk, in_key + AES_KEYSIZE_128);
	break;
	case AES_KEYSIZE_192:
	ctx->rounds = 5;
	ppc_expand_key_192(ctx->key_enc, in_key);
	ppc_expand_key_192(ctx->key_twk, in_key + AES_KEYSIZE_192);
	break;
	case AES_KEYSIZE_256:
	ctx->rounds = 6;
	ppc_expand_key_256(ctx->key_enc, in_key);
	ppc_expand_key_256(ctx->key_twk, in_key + AES_KEYSIZE_256);
	break;
	default:
	return -EINVAL;
	}

	ppc_generate_decrypt_key(ctx->key_dec, ctx->key_enc, key_len);

	return 0;
	}

	static int ppc_ecb_crypt(struct skcipher_request *req, bool enc)
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((nbytes = walk.nbytes) != 0) {
	nbytes = min(nbytes, MAX_BYTES);
	nbytes = round_down(nbytes, AES_BLOCK_SIZE);

	spe_begin();
	if (enc)
	ppc_encrypt_ecb(walk.dst.virt.addr, walk.src.virt.addr,
	ctx->key_enc, ctx->rounds, nbytes);
	else
	ppc_decrypt_ecb(walk.dst.virt.addr, walk.src.virt.addr,
	ctx->key_dec, ctx->rounds, nbytes);
	spe_end();

	err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
	}

	return err;
	}

	static int ppc_ecb_encrypt(struct skcipher_request *req)
	{
	return ppc_ecb_crypt(req, true);
	}

	static int ppc_ecb_decrypt(struct skcipher_request *req)
	{
	return ppc_ecb_crypt(req, false);
	}

	static int ppc_cbc_crypt(struct skcipher_request *req, bool enc)
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((nbytes = walk.nbytes) != 0) {
	nbytes = min(nbytes, MAX_BYTES);
	nbytes = round_down(nbytes, AES_BLOCK_SIZE);

	spe_begin();
	if (enc)
	ppc_encrypt_cbc(walk.dst.virt.addr, walk.src.virt.addr,
	ctx->key_enc, ctx->rounds, nbytes,
	walk.iv);
	else
	ppc_decrypt_cbc(walk.dst.virt.addr, walk.src.virt.addr,
	ctx->key_dec, ctx->rounds, nbytes,
	walk.iv);
	spe_end();

	err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
	}

	return err;
	}

	static int ppc_cbc_encrypt(struct skcipher_request *req)
	{
	return ppc_cbc_crypt(req, true);
	}

	static int ppc_cbc_decrypt(struct skcipher_request *req)
	{
	return ppc_cbc_crypt(req, false);
	}

	static int ppc_ctr_crypt(struct skcipher_request *req)
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((nbytes = walk.nbytes) != 0) {
	nbytes = min(nbytes, MAX_BYTES);
	if (nbytes < walk.total)
	nbytes = round_down(nbytes, AES_BLOCK_SIZE);

	spe_begin();
	ppc_crypt_ctr(walk.dst.virt.addr, walk.src.virt.addr,
	ctx->key_enc, ctx->rounds, nbytes, walk.iv);
	spe_end();

	err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
	}

	return err;
	}

	static int ppc_xts_crypt(struct skcipher_request *req, bool enc)
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	unsigned int nbytes;
	int err;
	u32 *twk;

	err = skcipher_walk_virt(&walk, req, false);
	twk = ctx->key_twk;

	while ((nbytes = walk.nbytes) != 0) {
	nbytes = min(nbytes, MAX_BYTES);
	nbytes = round_down(nbytes, AES_BLOCK_SIZE);

	spe_begin();
	if (enc)
	ppc_encrypt_xts(walk.dst.virt.addr, walk.src.virt.addr,
	ctx->key_enc, ctx->rounds, nbytes,
	walk.iv, twk);
	else
	ppc_decrypt_xts(walk.dst.virt.addr, walk.src.virt.addr,
	ctx->key_dec, ctx->rounds, nbytes,
	walk.iv, twk);
	spe_end();

	twk = NULL;
	err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
	}

	return err;
	}

	static int ppc_xts_encrypt(struct skcipher_request *req)
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
	int tail = req->cryptlen % AES_BLOCK_SIZE;
	int offset = req->cryptlen - tail - AES_BLOCK_SIZE;
	struct skcipher_request subreq;
	u8 b[2][AES_BLOCK_SIZE];
	int err;

	if (req->cryptlen < AES_BLOCK_SIZE)
	return -EINVAL;

	if (tail) {
	subreq = *req;
	skcipher_request_set_crypt(&subreq, req->src, req->dst,
	req->cryptlen - tail, req->iv);
	req = &subreq;
	}

	err = ppc_xts_crypt(req, true);
	if (err \|\| !tail)
	return err;

	scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE, 0);
	memcpy(b[1], b[0], tail);
	scatterwalk_map_and_copy(b[0], req->src, offset + AES_BLOCK_SIZE, tail, 0);

	spe_begin();
	ppc_encrypt_xts(b[0], b[0], ctx->key_enc, ctx->rounds, AES_BLOCK_SIZE,
	req->iv, NULL);
	spe_end();

	scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE + tail, 1);

	return 0;
	}

	static int ppc_xts_decrypt(struct skcipher_request *req)
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
	int tail = req->cryptlen % AES_BLOCK_SIZE;
	int offset = req->cryptlen - tail - AES_BLOCK_SIZE;
	struct skcipher_request subreq;
	u8 b[3][AES_BLOCK_SIZE];
	le128 twk;
	int err;

	if (req->cryptlen < AES_BLOCK_SIZE)
	return -EINVAL;

	if (tail) {
	subreq = *req;
	skcipher_request_set_crypt(&subreq, req->src, req->dst,
	offset, req->iv);
	req = &subreq;
	}

	err = ppc_xts_crypt(req, false);
	if (err \|\| !tail)
	return err;

	scatterwalk_map_and_copy(b[1], req->src, offset, AES_BLOCK_SIZE + tail, 0);

	spe_begin();
	if (!offset)
	ppc_encrypt_ecb(req->iv, req->iv, ctx->key_twk, ctx->rounds,
	AES_BLOCK_SIZE);

	gf128mul_x_ble(&twk, (le128 *)req->iv);

	ppc_decrypt_xts(b[1], b[1], ctx->key_dec, ctx->rounds, AES_BLOCK_SIZE,
	(u8 *)&twk, NULL);
	memcpy(b[0], b[2], tail);
	memcpy(b[0] + tail, b[1] + tail, AES_BLOCK_SIZE - tail);
	ppc_decrypt_xts(b[0], b[0], ctx->key_dec, ctx->rounds, AES_BLOCK_SIZE,
	req->iv, NULL);
	spe_end();

	scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE + tail, 1);

	return 0;
	}

	/*
	* Algorithm definitions. Disabling alignment (cra_alignmask=0) was chosen
	* because the e500 platform can handle unaligned reads/writes very efficiently.
	* This improves IPsec thoughput by another few percent. Additionally we assume
	* that AES context is always aligned to at least 8 bytes because it is created
	* with kmalloc() in the crypto infrastructure
	*/

	static struct skcipher_alg aes_skcipher_algs[] = {
	{
	.base.cra_name = "ecb(aes)",
	.base.cra_driver_name = "ecb-ppc-spe",
	.base.cra_priority = 300,
	.base.cra_blocksize = AES_BLOCK_SIZE,
	.base.cra_ctxsize = sizeof(struct ppc_aes_ctx),
	.base.cra_module = THIS_MODULE,
	.min_keysize = AES_MIN_KEY_SIZE,
	.max_keysize = AES_MAX_KEY_SIZE,
	.setkey = ppc_aes_setkey_skcipher,
	.encrypt = ppc_ecb_encrypt,
	.decrypt = ppc_ecb_decrypt,
	}, {
	.base.cra_name = "cbc(aes)",
	.base.cra_driver_name = "cbc-ppc-spe",
	.base.cra_priority = 300,
	.base.cra_blocksize = AES_BLOCK_SIZE,
	.base.cra_ctxsize = sizeof(struct ppc_aes_ctx),
	.base.cra_module = THIS_MODULE,
	.min_keysize = AES_MIN_KEY_SIZE,
	.max_keysize = AES_MAX_KEY_SIZE,
	.ivsize = AES_BLOCK_SIZE,
	.setkey = ppc_aes_setkey_skcipher,
	.encrypt = ppc_cbc_encrypt,
	.decrypt = ppc_cbc_decrypt,
	}, {
	.base.cra_name = "ctr(aes)",
	.base.cra_driver_name = "ctr-ppc-spe",
	.base.cra_priority = 300,
	.base.cra_blocksize = 1,
	.base.cra_ctxsize = sizeof(struct ppc_aes_ctx),
	.base.cra_module = THIS_MODULE,
	.min_keysize = AES_MIN_KEY_SIZE,
	.max_keysize = AES_MAX_KEY_SIZE,
	.ivsize = AES_BLOCK_SIZE,
	.setkey = ppc_aes_setkey_skcipher,
	.encrypt = ppc_ctr_crypt,
	.decrypt = ppc_ctr_crypt,
	.chunksize = AES_BLOCK_SIZE,
	}, {
	.base.cra_name = "xts(aes)",
	.base.cra_driver_name = "xts-ppc-spe",
	.base.cra_priority = 300,
	.base.cra_blocksize = AES_BLOCK_SIZE,
	.base.cra_ctxsize = sizeof(struct ppc_xts_ctx),
	.base.cra_module = THIS_MODULE,
	.min_keysize = AES_MIN_KEY_SIZE * 2,
	.max_keysize = AES_MAX_KEY_SIZE * 2,
	.ivsize = AES_BLOCK_SIZE,
	.setkey = ppc_xts_setkey,
	.encrypt = ppc_xts_encrypt,
	.decrypt = ppc_xts_decrypt,
	}
	};

	static int __init ppc_aes_mod_init(void)
	{
	return crypto_register_skciphers(aes_skcipher_algs,
	ARRAY_SIZE(aes_skcipher_algs));
	}

	static void __exit ppc_aes_mod_fini(void)
	{
	crypto_unregister_skciphers(aes_skcipher_algs,
	ARRAY_SIZE(aes_skcipher_algs));
	}

	module_init(ppc_aes_mod_init);
	module_exit(ppc_aes_mod_fini);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("AES-ECB/CBC/CTR/XTS, SPE optimized");

	MODULE_ALIAS_CRYPTO("aes");
	MODULE_ALIAS_CRYPTO("ecb(aes)");
	MODULE_ALIAS_CRYPTO("cbc(aes)");
	MODULE_ALIAS_CRYPTO("ctr(aes)");
	MODULE_ALIAS_CRYPTO("xts(aes)");
	MODULE_ALIAS_CRYPTO("aes-ppc-spe");