Michael Ellerman <m...@ellerman.id.au> writes:

> Daniel Axtens <d...@axtens.net> writes:
>> VMX ghash was using a fallback that did not support interleaving simd
>> and nosimd operations, leading to failures in the extended test suite.
>>
>> If I understood correctly, Eric's suggestion was to use the same
>> data format that the generic code uses, allowing us to call into it
>> with the same contexts. I wasn't able to get that to work - I think
>> there's a very different key structure and data layout being used.
>>
>> So instead steal the arm64 approach and perform the fallback
>> operations directly if required.
>>
>> Reported-by: Eric Biggers <ebigg...@google.com>
>> Signed-off-by: Daniel Axtens <d...@axtens.net>
>
> This probably needs a fixes tag?
>
> I assume it goes back to the original submission, ie.
>
>   Fixes: cc333cd68dfa ("crypto: vmx - Adding GHASH routines for VMX module")
>   Cc: sta...@vger.kernel.org # v4.1+
>
> Or did something change in the interim to expose this?

Yes, I think that's the right fixes tag. Not quite sure how I managed to
miss that! Herbert, I assume this will go via your tree: do you want me
to send a v2 with the tag or are you OK to just add that in when you
merge it?

Regards,
Daniel



>
>
>> ---
>>
>> Tested on BE and LE in qemu-tcg, so more testing would be lovely.
>
> I tested this on power8 with fuzz_iterations=10000, no problems.
> Previously it would fail very quickly.
>
> Tested-by: Michael Ellerman <m...@ellerman.id.au>
>
>
> cheers
>
>
>> diff --git a/drivers/crypto/vmx/ghash.c b/drivers/crypto/vmx/ghash.c
>> index b5a6883bb09e..14807ac2e3b9 100644
>> --- a/drivers/crypto/vmx/ghash.c
>> +++ b/drivers/crypto/vmx/ghash.c
>> @@ -1,22 +1,14 @@
>> +// SPDX-License-Identifier: GPL-2.0
>>  /**
>>   * GHASH routines supporting VMX instructions on the Power 8
>>   *
>> - * Copyright (C) 2015 International Business Machines Inc.
>> - *
>> - * This program is free software; you can redistribute it and/or modify
>> - * it under the terms of the GNU General Public License as published by
>> - * the Free Software Foundation; version 2 only.
>> - *
>> - * This program is distributed in the hope that it will be useful,
>> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> - * GNU General Public License for more details.
>> - *
>> - * You should have received a copy of the GNU General Public License
>> - * along with this program; if not, write to the Free Software
>> - * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
>> + * Copyright (C) 2015, 2019 International Business Machines Inc.
>>   *
>>   * Author: Marcelo Henrique Cerri <mhce...@br.ibm.com>
>> + *
>> + * Extended by Daniel Axtens <d...@axtens.net> to replace the fallback
>> + * mechanism. The new approach is based on arm64 code, which is:
>> + *   Copyright (C) 2014 - 2018 Linaro Ltd. <ard.biesheu...@linaro.org>
>>   */
>>  
>>  #include <linux/types.h>
>> @@ -38,70 +30,25 @@ void gcm_ghash_p8(u64 Xi[2], const u128 htable[16],
>>                const u8 *in, size_t len);
>>  
>>  struct p8_ghash_ctx {
>> +    /* key used by vector asm */
>>      u128 htable[16];
>> -    struct crypto_shash *fallback;
>> +    /* key used by software fallback */
>> +    be128 key;
>>  };
>>  
>>  struct p8_ghash_desc_ctx {
>>      u64 shash[2];
>>      u8 buffer[GHASH_DIGEST_SIZE];
>>      int bytes;
>> -    struct shash_desc fallback_desc;
>>  };
>>  
>> -static int p8_ghash_init_tfm(struct crypto_tfm *tfm)
>> -{
>> -    const char *alg = "ghash-generic";
>> -    struct crypto_shash *fallback;
>> -    struct crypto_shash *shash_tfm = __crypto_shash_cast(tfm);
>> -    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
>> -
>> -    fallback = crypto_alloc_shash(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
>> -    if (IS_ERR(fallback)) {
>> -            printk(KERN_ERR
>> -                   "Failed to allocate transformation for '%s': %ld\n",
>> -                   alg, PTR_ERR(fallback));
>> -            return PTR_ERR(fallback);
>> -    }
>> -
>> -    crypto_shash_set_flags(fallback,
>> -                           crypto_shash_get_flags((struct crypto_shash
>> -                                                   *) tfm));
>> -
>> -    /* Check if the descsize defined in the algorithm is still enough. */
>> -    if (shash_tfm->descsize < sizeof(struct p8_ghash_desc_ctx)
>> -        + crypto_shash_descsize(fallback)) {
>> -            printk(KERN_ERR
>> -                   "Desc size of the fallback implementation (%s) does not 
>> match the expected value: %lu vs %u\n",
>> -                   alg,
>> -                   shash_tfm->descsize - sizeof(struct p8_ghash_desc_ctx),
>> -                   crypto_shash_descsize(fallback));
>> -            return -EINVAL;
>> -    }
>> -    ctx->fallback = fallback;
>> -
>> -    return 0;
>> -}
>> -
>> -static void p8_ghash_exit_tfm(struct crypto_tfm *tfm)
>> -{
>> -    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
>> -
>> -    if (ctx->fallback) {
>> -            crypto_free_shash(ctx->fallback);
>> -            ctx->fallback = NULL;
>> -    }
>> -}
>> -
>>  static int p8_ghash_init(struct shash_desc *desc)
>>  {
>> -    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
>>      struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
>>  
>>      dctx->bytes = 0;
>>      memset(dctx->shash, 0, GHASH_DIGEST_SIZE);
>> -    dctx->fallback_desc.tfm = ctx->fallback;
>> -    return crypto_shash_init(&dctx->fallback_desc);
>> +    return 0;
>>  }
>>  
>>  static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
>> @@ -119,7 +66,51 @@ static int p8_ghash_setkey(struct crypto_shash *tfm, 
>> const u8 *key,
>>      disable_kernel_vsx();
>>      pagefault_enable();
>>      preempt_enable();
>> -    return crypto_shash_setkey(ctx->fallback, key, keylen);
>> +
>> +    memcpy(&ctx->key, key, GHASH_BLOCK_SIZE);
>> +
>> +    return 0;
>> +}
>> +
>> +static inline void __ghash_block(struct p8_ghash_ctx *ctx,
>> +                             struct p8_ghash_desc_ctx *dctx)
>> +{
>> +    if (crypto_simd_usable()) {
>> +            preempt_disable();
>> +            pagefault_disable();
>> +            enable_kernel_vsx();
>> +            gcm_ghash_p8(dctx->shash, ctx->htable,
>> +                            dctx->buffer, GHASH_DIGEST_SIZE);
>> +            disable_kernel_vsx();
>> +            pagefault_enable();
>> +            preempt_enable();
>> +    } else {
>> +            crypto_xor((u8 *)dctx->shash, dctx->buffer, GHASH_BLOCK_SIZE);
>> +            gf128mul_lle((be128 *)dctx->shash, &ctx->key);
>> +    }
>> +}
>> +
>> +static inline void __ghash_blocks(struct p8_ghash_ctx *ctx,
>> +                              struct p8_ghash_desc_ctx *dctx,
>> +                              const u8 *src, unsigned int srclen)
>> +{
>> +    if (crypto_simd_usable()) {
>> +            preempt_disable();
>> +            pagefault_disable();
>> +            enable_kernel_vsx();
>> +            gcm_ghash_p8(dctx->shash, ctx->htable,
>> +                            src, srclen);
>> +            disable_kernel_vsx();
>> +            pagefault_enable();
>> +            preempt_enable();
>> +    } else {
>> +            while (srclen >= GHASH_BLOCK_SIZE) {
>> +                    crypto_xor((u8 *)dctx->shash, src, GHASH_BLOCK_SIZE);
>> +                    gf128mul_lle((be128 *)dctx->shash, &ctx->key);
>> +                    srclen -= GHASH_BLOCK_SIZE;
>> +                    src += GHASH_BLOCK_SIZE;
>> +            }
>> +    }
>>  }
>>  
>>  static int p8_ghash_update(struct shash_desc *desc,
>> @@ -129,49 +120,33 @@ static int p8_ghash_update(struct shash_desc *desc,
>>      struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
>>      struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
>>  
>> -    if (!crypto_simd_usable()) {
>> -            return crypto_shash_update(&dctx->fallback_desc, src,
>> -                                       srclen);
>> -    } else {
>> -            if (dctx->bytes) {
>> -                    if (dctx->bytes + srclen < GHASH_DIGEST_SIZE) {
>> -                            memcpy(dctx->buffer + dctx->bytes, src,
>> -                                   srclen);
>> -                            dctx->bytes += srclen;
>> -                            return 0;
>> -                    }
>> +    if (dctx->bytes) {
>> +            if (dctx->bytes + srclen < GHASH_DIGEST_SIZE) {
>>                      memcpy(dctx->buffer + dctx->bytes, src,
>> -                           GHASH_DIGEST_SIZE - dctx->bytes);
>> -                    preempt_disable();
>> -                    pagefault_disable();
>> -                    enable_kernel_vsx();
>> -                    gcm_ghash_p8(dctx->shash, ctx->htable,
>> -                                 dctx->buffer, GHASH_DIGEST_SIZE);
>> -                    disable_kernel_vsx();
>> -                    pagefault_enable();
>> -                    preempt_enable();
>> -                    src += GHASH_DIGEST_SIZE - dctx->bytes;
>> -                    srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
>> -                    dctx->bytes = 0;
>> -            }
>> -            len = srclen & ~(GHASH_DIGEST_SIZE - 1);
>> -            if (len) {
>> -                    preempt_disable();
>> -                    pagefault_disable();
>> -                    enable_kernel_vsx();
>> -                    gcm_ghash_p8(dctx->shash, ctx->htable, src, len);
>> -                    disable_kernel_vsx();
>> -                    pagefault_enable();
>> -                    preempt_enable();
>> -                    src += len;
>> -                    srclen -= len;
>> -            }
>> -            if (srclen) {
>> -                    memcpy(dctx->buffer, src, srclen);
>> -                    dctx->bytes = srclen;
>> +                            srclen);
>> +                    dctx->bytes += srclen;
>> +                    return 0;
>>              }
>> -            return 0;
>> +            memcpy(dctx->buffer + dctx->bytes, src,
>> +                    GHASH_DIGEST_SIZE - dctx->bytes);
>> +
>> +            __ghash_block(ctx, dctx);
>> +
>> +            src += GHASH_DIGEST_SIZE - dctx->bytes;
>> +            srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
>> +            dctx->bytes = 0;
>> +    }
>> +    len = srclen & ~(GHASH_DIGEST_SIZE - 1);
>> +    if (len) {
>> +            __ghash_blocks(ctx, dctx, src, len);
>> +            src += len;
>> +            srclen -= len;
>>      }
>> +    if (srclen) {
>> +            memcpy(dctx->buffer, src, srclen);
>> +            dctx->bytes = srclen;
>> +    }
>> +    return 0;
>>  }
>>  
>>  static int p8_ghash_final(struct shash_desc *desc, u8 *out)
>> @@ -180,25 +155,14 @@ static int p8_ghash_final(struct shash_desc *desc, u8 
>> *out)
>>      struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));
>>      struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
>>  
>> -    if (!crypto_simd_usable()) {
>> -            return crypto_shash_final(&dctx->fallback_desc, out);
>> -    } else {
>> -            if (dctx->bytes) {
>> -                    for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)
>> -                            dctx->buffer[i] = 0;
>> -                    preempt_disable();
>> -                    pagefault_disable();
>> -                    enable_kernel_vsx();
>> -                    gcm_ghash_p8(dctx->shash, ctx->htable,
>> -                                 dctx->buffer, GHASH_DIGEST_SIZE);
>> -                    disable_kernel_vsx();
>> -                    pagefault_enable();
>> -                    preempt_enable();
>> -                    dctx->bytes = 0;
>> -            }
>> -            memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
>> -            return 0;
>> +    if (dctx->bytes) {
>> +            for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)
>> +                    dctx->buffer[i] = 0;
>> +            __ghash_block(ctx, dctx);
>> +            dctx->bytes = 0;
>>      }
>> +    memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
>> +    return 0;
>>  }
>>  
>>  struct shash_alg p8_ghash_alg = {
>> @@ -213,11 +177,8 @@ struct shash_alg p8_ghash_alg = {
>>               .cra_name = "ghash",
>>               .cra_driver_name = "p8_ghash",
>>               .cra_priority = 1000,
>> -             .cra_flags = CRYPTO_ALG_NEED_FALLBACK,
>>               .cra_blocksize = GHASH_BLOCK_SIZE,
>>               .cra_ctxsize = sizeof(struct p8_ghash_ctx),
>>               .cra_module = THIS_MODULE,
>> -             .cra_init = p8_ghash_init_tfm,
>> -             .cra_exit = p8_ghash_exit_tfm,
>>      },
>>  };
>> -- 
>> 2.19.1

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