// SPDX-License-Identifier: GPL-2.0-only
/* 
 * Cryptographic API.
 *
 * Support for VIA PadLock hardware crypto engine.
 *
 * Copyright (c) 2004  Michal Ludvig <michal@logix.cz>
 *
 */

#include <crypto/algapi.h>
#include <crypto/aes.h>
#include <crypto/internal/skcipher.h>
#include <crypto/padlock.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/slab.h>
#include <asm/cpu_device_id.h>
#include <asm/byteorder.h>
#include <asm/processor.h>
#include <asm/fpu/api.h>

/*
 * Number of data blocks actually fetched for each xcrypt insn.
 * Processors with prefetch errata will fetch extra blocks.
 */
static unsigned int ecb_fetch_blocks = 2;
#define MAX_ECB_FETCH_BLOCKS (8)
#define ecb_fetch_bytes (ecb_fetch_blocks * AES_BLOCK_SIZE)

static unsigned int cbc_fetch_blocks = 1;
#define MAX_CBC_FETCH_BLOCKS (4)
#define cbc_fetch_bytes (cbc_fetch_blocks * AES_BLOCK_SIZE)

/* Control word. */
struct cword {
        unsigned int __attribute__ ((__packed__))
                rounds:4,
                algo:3,
                keygen:1,
                interm:1,
                encdec:1,
                ksize:2;
} __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));

/* Whenever making any changes to the following
 * structure *make sure* you keep E, d_data
 * and cword aligned on 16 Bytes boundaries and
 * the Hardware can access 16 * 16 bytes of E and d_data
 * (only the first 15 * 16 bytes matter but the HW reads
 * more).
 */
struct aes_ctx {
        u32 E[AES_MAX_KEYLENGTH_U32]
                __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
        u32 d_data[AES_MAX_KEYLENGTH_U32]
                __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
        struct {
                struct cword encrypt;
                struct cword decrypt;
        } cword;
        u32 *D;
};

static DEFINE_PER_CPU(struct cword *, paes_last_cword);

/* Tells whether the ACE is capable to generate
   the extended key for a given key_len. */
static inline int
aes_hw_extkey_available(uint8_t key_len)
{
        /* TODO: We should check the actual CPU model/stepping
                 as it's possible that the capability will be
                 added in the next CPU revisions. */
        if (key_len == 16)
                return 1;
        return 0;
}

static inline struct aes_ctx *aes_ctx_common(void *ctx)
{
        unsigned long addr = (unsigned long)ctx;
        unsigned long align = PADLOCK_ALIGNMENT;

        if (align <= crypto_tfm_ctx_alignment())
                align = 1;
        return (struct aes_ctx *)ALIGN(addr, align);
}

static inline struct aes_ctx *aes_ctx(struct crypto_tfm *tfm)
{
        return aes_ctx_common(crypto_tfm_ctx(tfm));
}

static inline struct aes_ctx *skcipher_aes_ctx(struct crypto_skcipher *tfm)
{
        return aes_ctx_common(crypto_skcipher_ctx(tfm));
}

static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
                       unsigned int key_len)
{
        struct aes_ctx *ctx = aes_ctx(tfm);
        const __le32 *key = (const __le32 *)in_key;
        struct crypto_aes_ctx gen_aes;
        int cpu;

        if (key_len % 8)
                return -EINVAL;

        /*
         * If the hardware is capable of generating the extended key
         * itself we must supply the plain key for both encryption
         * and decryption.
         */
        ctx->D = ctx->E;

        ctx->E[0] = le32_to_cpu(key[0]);
        ctx->E[1] = le32_to_cpu(key[1]);
        ctx->E[2] = le32_to_cpu(key[2]);
        ctx->E[3] = le32_to_cpu(key[3]);

        /* Prepare control words. */
        memset(&ctx->cword, 0, sizeof(ctx->cword));

        ctx->cword.decrypt.encdec = 1;
        ctx->cword.encrypt.rounds = 10 + (key_len - 16) / 4;
        ctx->cword.decrypt.rounds = ctx->cword.encrypt.rounds;
        ctx->cword.encrypt.ksize = (key_len - 16) / 8;
        ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;

        /* Don't generate extended keys if the hardware can do it. */
        if (aes_hw_extkey_available(key_len))
                goto ok;

        ctx->D = ctx->d_data;
        ctx->cword.encrypt.keygen = 1;
        ctx->cword.decrypt.keygen = 1;

        if (aes_expandkey(&gen_aes, in_key, key_len))
                return -EINVAL;

        memcpy(ctx->E, gen_aes.key_enc, AES_MAX_KEYLENGTH);
        memcpy(ctx->D, gen_aes.key_dec, AES_MAX_KEYLENGTH);

ok:
        for_each_online_cpu(cpu)
                if (&ctx->cword.encrypt == per_cpu(paes_last_cword, cpu) ||
                    &ctx->cword.decrypt == per_cpu(paes_last_cword, cpu))
                        per_cpu(paes_last_cword, cpu) = NULL;

        return 0;
}

static int aes_set_key_skcipher(struct crypto_skcipher *tfm, const u8 *in_key,
                                unsigned int key_len)
{
        return aes_set_key(crypto_skcipher_tfm(tfm), in_key, key_len);
}

/* ====== Encryption/decryption routines ====== */

/* These are the real call to PadLock. */
static inline void padlock_reset_key(struct cword *cword)
{
        int cpu = raw_smp_processor_id();

        if (cword != per_cpu(paes_last_cword, cpu))
#ifndef CONFIG_X86_64
                asm volatile ("pushfl; popfl");
#else
                asm volatile ("pushfq; popfq");
#endif
}

static inline void padlock_store_cword(struct cword *cword)
{
        per_cpu(paes_last_cword, raw_smp_processor_id()) = cword;
}

/*
 * While the padlock instructions don't use FP/SSE registers, they
 * generate a spurious DNA fault when CR0.TS is '1'.  Fortunately,
 * the kernel doesn't use CR0.TS.
 */

static inline void rep_xcrypt_ecb(const u8 *input, u8 *output, void *key,
                                  struct cword *control_word, int count)
{
        asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
                      : "+S"(input), "+D"(output)
                      : "d"(control_word), "b"(key), "c"(count));
}

static inline u8 *rep_xcrypt_cbc(const u8 *input, u8 *output, void *key,
                                 u8 *iv, struct cword *control_word, int count)
{
        asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
                      : "+S" (input), "+D" (output), "+a" (iv)
                      : "d" (control_word), "b" (key), "c" (count));
        return iv;
}

static void ecb_crypt_copy(const u8 *in, u8 *out, u32 *key,
                           struct cword *cword, int count)
{
        /*
         * Padlock prefetches extra data so we must provide mapped input buffers.
         * Assume there are at least 16 bytes of stack already in use.
         */
        u8 buf[AES_BLOCK_SIZE * (MAX_ECB_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
        u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);

        memcpy(tmp, in, count * AES_BLOCK_SIZE);
        rep_xcrypt_ecb(tmp, out, key, cword, count);
}

static u8 *cbc_crypt_copy(const u8 *in, u8 *out, u32 *key,
                           u8 *iv, struct cword *cword, int count)
{
        /*
         * Padlock prefetches extra data so we must provide mapped input buffers.
         * Assume there are at least 16 bytes of stack already in use.
         */
        u8 buf[AES_BLOCK_SIZE * (MAX_CBC_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
        u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);

        memcpy(tmp, in, count * AES_BLOCK_SIZE);
        return rep_xcrypt_cbc(tmp, out, key, iv, cword, count);
}

static inline void ecb_crypt(const u8 *in, u8 *out, u32 *key,
                             struct cword *cword, int count)
{
        /* Padlock in ECB mode fetches at least ecb_fetch_bytes of data.
         * We could avoid some copying here but it's probably not worth it.
         */
        if (unlikely(offset_in_page(in) + ecb_fetch_bytes > PAGE_SIZE)) {
                ecb_crypt_copy(in, out, key, cword, count);
                return;
        }

        rep_xcrypt_ecb(in, out, key, cword, count);
}

static inline u8 *cbc_crypt(const u8 *in, u8 *out, u32 *key,
                            u8 *iv, struct cword *cword, int count)
{
        /* Padlock in CBC mode fetches at least cbc_fetch_bytes of data. */
        if (unlikely(offset_in_page(in) + cbc_fetch_bytes > PAGE_SIZE))
                return cbc_crypt_copy(in, out, key, iv, cword, count);

        return rep_xcrypt_cbc(in, out, key, iv, cword, count);
}

static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
                                      void *control_word, u32 count)
{
        u32 initial = count & (ecb_fetch_blocks - 1);

        if (count < ecb_fetch_blocks) {
                ecb_crypt(input, output, key, control_word, count);
                return;
        }

        count -= initial;

        if (initial)
                asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
                              : "+S"(input), "+D"(output)
                              : "d"(control_word), "b"(key), "c"(initial));

        asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
                      : "+S"(input), "+D"(output)
                      : "d"(control_word), "b"(key), "c"(count));
}

static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
                                     u8 *iv, void *control_word, u32 count)
{
        u32 initial = count & (cbc_fetch_blocks - 1);

        if (count < cbc_fetch_blocks)
                return cbc_crypt(input, output, key, iv, control_word, count);

        count -= initial;

        if (initial)
                asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
                              : "+S" (input), "+D" (output), "+a" (iv)
                              : "d" (control_word), "b" (key), "c" (initial));

        asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
                      : "+S" (input), "+D" (output), "+a" (iv)
                      : "d" (control_word), "b" (key), "c" (count));
        return iv;
}

static void padlock_aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
        struct aes_ctx *ctx = aes_ctx(tfm);

        padlock_reset_key(&ctx->cword.encrypt);
        ecb_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
        padlock_store_cword(&ctx->cword.encrypt);
}

static void padlock_aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
        struct aes_ctx *ctx = aes_ctx(tfm);

        padlock_reset_key(&ctx->cword.encrypt);
        ecb_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
        padlock_store_cword(&ctx->cword.encrypt);
}

static struct crypto_alg aes_alg = {
        .cra_name               =       "aes",
        .cra_driver_name        =       "aes-padlock",
        .cra_priority           =       PADLOCK_CRA_PRIORITY,
        .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
        .cra_blocksize          =       AES_BLOCK_SIZE,
        .cra_ctxsize            =       sizeof(struct aes_ctx),
        .cra_alignmask          =       PADLOCK_ALIGNMENT - 1,
        .cra_module             =       THIS_MODULE,
        .cra_u                  =       {
                .cipher = {
                        .cia_min_keysize        =       AES_MIN_KEY_SIZE,
                        .cia_max_keysize        =       AES_MAX_KEY_SIZE,
                        .cia_setkey             =       aes_set_key,
                        .cia_encrypt            =       padlock_aes_encrypt,
                        .cia_decrypt            =       padlock_aes_decrypt,
                }
        }
};

static int ecb_aes_encrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct aes_ctx *ctx = skcipher_aes_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        int err;

        padlock_reset_key(&ctx->cword.encrypt);

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

        while ((nbytes = walk.nbytes) != 0) {
                padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
                                   ctx->E, &ctx->cword.encrypt,
                                   nbytes / AES_BLOCK_SIZE);
                nbytes &= AES_BLOCK_SIZE - 1;
                err = skcipher_walk_done(&walk, nbytes);
        }

        padlock_store_cword(&ctx->cword.encrypt);

        return err;
}

static int ecb_aes_decrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct aes_ctx *ctx = skcipher_aes_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        int err;

        padlock_reset_key(&ctx->cword.decrypt);

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

        while ((nbytes = walk.nbytes) != 0) {
                padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
                                   ctx->D, &ctx->cword.decrypt,
                                   nbytes / AES_BLOCK_SIZE);
                nbytes &= AES_BLOCK_SIZE - 1;
                err = skcipher_walk_done(&walk, nbytes);
        }

        padlock_store_cword(&ctx->cword.encrypt);

        return err;
}

static struct skcipher_alg ecb_aes_alg = {
        .base.cra_name          =       "ecb(aes)",
        .base.cra_driver_name   =       "ecb-aes-padlock",
        .base.cra_priority      =       PADLOCK_COMPOSITE_PRIORITY,
        .base.cra_blocksize     =       AES_BLOCK_SIZE,
        .base.cra_ctxsize       =       sizeof(struct aes_ctx),
        .base.cra_alignmask     =       PADLOCK_ALIGNMENT - 1,
        .base.cra_module        =       THIS_MODULE,
        .min_keysize            =       AES_MIN_KEY_SIZE,
        .max_keysize            =       AES_MAX_KEY_SIZE,
        .setkey                 =       aes_set_key_skcipher,
        .encrypt                =       ecb_aes_encrypt,
        .decrypt                =       ecb_aes_decrypt,
};

static int cbc_aes_encrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct aes_ctx *ctx = skcipher_aes_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        int err;

        padlock_reset_key(&ctx->cword.encrypt);

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

        while ((nbytes = walk.nbytes) != 0) {
                u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
                                            walk.dst.virt.addr, ctx->E,
                                            walk.iv, &ctx->cword.encrypt,
                                            nbytes / AES_BLOCK_SIZE);
                memcpy(walk.iv, iv, AES_BLOCK_SIZE);
                nbytes &= AES_BLOCK_SIZE - 1;
                err = skcipher_walk_done(&walk, nbytes);
        }

        padlock_store_cword(&ctx->cword.decrypt);

        return err;
}

static int cbc_aes_decrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct aes_ctx *ctx = skcipher_aes_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        int err;

        padlock_reset_key(&ctx->cword.encrypt);

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

        while ((nbytes = walk.nbytes) != 0) {
                padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
                                   ctx->D, walk.iv, &ctx->cword.decrypt,
                                   nbytes / AES_BLOCK_SIZE);
                nbytes &= AES_BLOCK_SIZE - 1;
                err = skcipher_walk_done(&walk, nbytes);
        }

        padlock_store_cword(&ctx->cword.encrypt);

        return err;
}

static struct skcipher_alg cbc_aes_alg = {
        .base.cra_name          =       "cbc(aes)",
        .base.cra_driver_name   =       "cbc-aes-padlock",
        .base.cra_priority      =       PADLOCK_COMPOSITE_PRIORITY,
        .base.cra_blocksize     =       AES_BLOCK_SIZE,
        .base.cra_ctxsize       =       sizeof(struct aes_ctx),
        .base.cra_alignmask     =       PADLOCK_ALIGNMENT - 1,
        .base.cra_module        =       THIS_MODULE,
        .min_keysize            =       AES_MIN_KEY_SIZE,
        .max_keysize            =       AES_MAX_KEY_SIZE,
        .ivsize                 =       AES_BLOCK_SIZE,
        .setkey                 =       aes_set_key_skcipher,
        .encrypt                =       cbc_aes_encrypt,
        .decrypt                =       cbc_aes_decrypt,
};

static const struct x86_cpu_id padlock_cpu_id[] = {
        X86_MATCH_FEATURE(X86_FEATURE_XCRYPT, NULL),
        {}
};
MODULE_DEVICE_TABLE(x86cpu, padlock_cpu_id);

static int __init padlock_init(void)
{
        int ret;
        struct cpuinfo_x86 *c = &cpu_data(0);

        if (!x86_match_cpu(padlock_cpu_id))
                return -ENODEV;

        if (!boot_cpu_has(X86_FEATURE_XCRYPT_EN)) {
                printk(KERN_NOTICE PFX "VIA PadLock detected, but not enabled. Hmm, strange...\n");
                return -ENODEV;
        }

        if ((ret = crypto_register_alg(&aes_alg)) != 0)
                goto aes_err;

        if ((ret = crypto_register_skcipher(&ecb_aes_alg)) != 0)
                goto ecb_aes_err;

        if ((ret = crypto_register_skcipher(&cbc_aes_alg)) != 0)
                goto cbc_aes_err;

        printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");

        if (c->x86 == 6 && c->x86_model == 15 && c->x86_stepping == 2) {
                ecb_fetch_blocks = MAX_ECB_FETCH_BLOCKS;
                cbc_fetch_blocks = MAX_CBC_FETCH_BLOCKS;
                printk(KERN_NOTICE PFX "VIA Nano stepping 2 detected: enabling workaround.\n");
        }

out:
        return ret;

cbc_aes_err:
        crypto_unregister_skcipher(&ecb_aes_alg);
ecb_aes_err:
        crypto_unregister_alg(&aes_alg);
aes_err:
        printk(KERN_ERR PFX "VIA PadLock AES initialization failed.\n");
        goto out;
}

static void __exit padlock_fini(void)
{
        crypto_unregister_skcipher(&cbc_aes_alg);
        crypto_unregister_skcipher(&ecb_aes_alg);
        crypto_unregister_alg(&aes_alg);
}

module_init(padlock_init);
module_exit(padlock_fini);

MODULE_DESCRIPTION("VIA PadLock AES algorithm support");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michal Ludvig");

MODULE_ALIAS_CRYPTO("aes");