// SPDX-License-Identifier: GPL-2.0-only
/*
 * AES CTR routines supporting VMX instructions on the Power 8
 *
 * Copyright (C) 2015 International Business Machines Inc.
 *
 * Author: Marcelo Henrique Cerri <mhcerri@br.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 <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/uaccess.h>

#include "aesp8-ppc.h"

struct p8_aes_ctr_ctx {
        struct crypto_skcipher *fallback;
        struct p8_aes_key enc_key;
};

static int p8_aes_ctr_init(struct crypto_skcipher *tfm)
{
        struct p8_aes_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
        struct crypto_skcipher *fallback;

        fallback = crypto_alloc_skcipher("ctr(aes)", 0,
                                         CRYPTO_ALG_NEED_FALLBACK |
                                         CRYPTO_ALG_ASYNC);
        if (IS_ERR(fallback)) {
                pr_err("Failed to allocate ctr(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_ctr_exit(struct crypto_skcipher *tfm)
{
        struct p8_aes_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);

        crypto_free_skcipher(ctx->fallback);
}

static int p8_aes_ctr_setkey(struct crypto_skcipher *tfm, const u8 *key,
                             unsigned int keylen)
{
        struct p8_aes_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
        int ret;

        preempt_disable();
        pagefault_disable();
        enable_kernel_vsx();
        ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
        disable_kernel_vsx();
        pagefault_enable();
        preempt_enable();

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

        return ret ? -EINVAL : 0;
}

static void p8_aes_ctr_final(const struct p8_aes_ctr_ctx *ctx,
                             struct skcipher_walk *walk)
{
        const u8 *src = walk->src.virt.addr;
        u8 *ctrblk = walk->iv;
        u8 keystream[AES_BLOCK_SIZE];
        u8 *dst = walk->dst.virt.addr;
        unsigned int nbytes = walk->nbytes;

        preempt_disable();
        pagefault_disable();
        enable_kernel_vsx();
        aes_p8_encrypt(ctrblk, keystream, &ctx->enc_key);
        disable_kernel_vsx();
        pagefault_enable();
        preempt_enable();

        crypto_xor_cpy(dst, keystream, src, nbytes);
        crypto_inc(ctrblk, AES_BLOCK_SIZE);
}

static int p8_aes_ctr_crypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        const struct p8_aes_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        int ret;

        if (!crypto_simd_usable()) {
                struct skcipher_request *subreq = skcipher_request_ctx(req);

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

        ret = skcipher_walk_virt(&walk, req, false);
        while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
                preempt_disable();
                pagefault_disable();
                enable_kernel_vsx();
                aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
                                            walk.dst.virt.addr,
                                            nbytes / AES_BLOCK_SIZE,
                                            &ctx->enc_key, walk.iv);
                disable_kernel_vsx();
                pagefault_enable();
                preempt_enable();

                do {
                        crypto_inc(walk.iv, AES_BLOCK_SIZE);
                } while ((nbytes -= AES_BLOCK_SIZE) >= AES_BLOCK_SIZE);

                ret = skcipher_walk_done(&walk, nbytes);
        }
        if (nbytes) {
                p8_aes_ctr_final(ctx, &walk);
                ret = skcipher_walk_done(&walk, 0);
        }
        return ret;
}

struct skcipher_alg p8_aes_ctr_alg = {
        .base.cra_name = "ctr(aes)",
        .base.cra_driver_name = "p8_aes_ctr",
        .base.cra_module = THIS_MODULE,
        .base.cra_priority = 2000,
        .base.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
        .base.cra_blocksize = 1,
        .base.cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
        .setkey = p8_aes_ctr_setkey,
        .encrypt = p8_aes_ctr_crypt,
        .decrypt = p8_aes_ctr_crypt,
        .init = p8_aes_ctr_init,
        .exit = p8_aes_ctr_exit,
        .min_keysize = AES_MIN_KEY_SIZE,
        .max_keysize = AES_MAX_KEY_SIZE,
        .ivsize = AES_BLOCK_SIZE,
        .chunksize = AES_BLOCK_SIZE,
};