// SPDX-License-Identifier: GPL-2.0-only
/*
 * AES XTS routines supporting VMX In-core instructions on Power 8
 *
 * Copyright (C) 2015 International Business Machines Inc.
 *
 * Author: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
 */

#include <asm/simd.h>
#include <asm/switch_to.h>
#include <crypto/aes.h>
#include <crypto/internal/simd.h>
#include <crypto/internal/skcipher.h>
#include <crypto/xts.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/uaccess.h>

#include "aesp8-ppc.h"

struct p8_aes_xts_ctx {
        struct crypto_skcipher *fallback;
        struct p8_aes_key enc_key;
        struct p8_aes_key dec_key;
        struct p8_aes_key tweak_key;
};

static int p8_aes_xts_init(struct crypto_skcipher *tfm)
{
        struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
        struct crypto_skcipher *fallback;

        fallback = crypto_alloc_skcipher("xts(aes)", 0,
                                         CRYPTO_ALG_NEED_FALLBACK |
                                         CRYPTO_ALG_ASYNC);
        if (IS_ERR(fallback)) {
                pr_err("Failed to allocate xts(aes) fallback: %ld\n",
                       PTR_ERR(fallback));
                return PTR_ERR(fallback);
        }

        crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
                                    crypto_skcipher_reqsize(fallback));
        ctx->fallback = fallback;
        return 0;
}

static void p8_aes_xts_exit(struct crypto_skcipher *tfm)
{
        struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);

        crypto_free_skcipher(ctx->fallback);
}

static int p8_aes_xts_setkey(struct crypto_skcipher *tfm, const u8 *key,
                             unsigned int keylen)
{
        struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
        int ret;

        ret = xts_verify_key(tfm, key, keylen);
        if (ret)
                return ret;

        preempt_disable();
        pagefault_disable();
        enable_kernel_vsx();
        ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key);
        ret |= aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key);
        ret |= aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key);
        disable_kernel_vsx();
        pagefault_enable();
        preempt_enable();

        ret |= crypto_skcipher_setkey(ctx->fallback, key, keylen);

        return ret ? -EINVAL : 0;
}

static int p8_aes_xts_crypt(struct skcipher_request *req, int enc)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        const struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        u8 tweak[AES_BLOCK_SIZE];
        int ret;

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

        if (!crypto_simd_usable() || (req->cryptlen % XTS_BLOCK_SIZE) != 0) {
                struct skcipher_request *subreq = skcipher_request_ctx(req);

                *subreq = *req;
                skcipher_request_set_tfm(subreq, ctx->fallback);
                return enc ? crypto_skcipher_encrypt(subreq) :
                             crypto_skcipher_decrypt(subreq);
        }

        ret = skcipher_walk_virt(&walk, req, false);
        if (ret)
                return ret;

        preempt_disable();
        pagefault_disable();
        enable_kernel_vsx();

        aes_p8_encrypt(walk.iv, tweak, &ctx->tweak_key);

        disable_kernel_vsx();
        pagefault_enable();
        preempt_enable();

        while ((nbytes = walk.nbytes) != 0) {
                preempt_disable();
                pagefault_disable();
                enable_kernel_vsx();
                if (enc)
                        aes_p8_xts_encrypt(walk.src.virt.addr,
                                           walk.dst.virt.addr,
                                           round_down(nbytes, AES_BLOCK_SIZE),
                                           &ctx->enc_key, NULL, tweak);
                else
                        aes_p8_xts_decrypt(walk.src.virt.addr,
                                           walk.dst.virt.addr,
                                           round_down(nbytes, AES_BLOCK_SIZE),
                                           &ctx->dec_key, NULL, tweak);
                disable_kernel_vsx();
                pagefault_enable();
                preempt_enable();

                ret = skcipher_walk_done(&walk, nbytes % AES_BLOCK_SIZE);
        }
        return ret;
}

static int p8_aes_xts_encrypt(struct skcipher_request *req)
{
        return p8_aes_xts_crypt(req, 1);
}

static int p8_aes_xts_decrypt(struct skcipher_request *req)
{
        return p8_aes_xts_crypt(req, 0);
}

struct skcipher_alg p8_aes_xts_alg = {
        .base.cra_name = "xts(aes)",
        .base.cra_driver_name = "p8_aes_xts",
        .base.cra_module = THIS_MODULE,
        .base.cra_priority = 2000,
        .base.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
        .base.cra_blocksize = AES_BLOCK_SIZE,
        .base.cra_ctxsize = sizeof(struct p8_aes_xts_ctx),
        .setkey = p8_aes_xts_setkey,
        .encrypt = p8_aes_xts_encrypt,
        .decrypt = p8_aes_xts_decrypt,
        .init = p8_aes_xts_init,
        .exit = p8_aes_xts_exit,
        .min_keysize = 2 * AES_MIN_KEY_SIZE,
        .max_keysize = 2 * AES_MAX_KEY_SIZE,
        .ivsize = AES_BLOCK_SIZE,
};