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crypto: algapi - make crypto_xor() take separate dst and src arguments

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There are quite a number of occurrences in the kernel of the pattern

  if (dst != src)
          memcpy(dst, src, walk.total % AES_BLOCK_SIZE);
  crypto_xor(dst, final, walk.total % AES_BLOCK_SIZE);

or

  crypto_xor(keystream, src, nbytes);
  memcpy(dst, keystream, nbytes);

where crypto_xor() is preceded or followed by a memcpy() invocation
that is only there because crypto_xor() uses its output parameter as
one of the inputs. To avoid having to add new instances of this pattern
in the arm64 code, which will be refactored to implement non-SIMD
fallbacks, add an alternative implementation called crypto_xor_cpy(),
taking separate input and output arguments. This removes the need for
the separate memcpy().

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel 2017-07-24 11:28:04 +01:00 • committed by Herbert Xu
commit 45fe93dff2
1 changed files with 42 additions and 40 deletions
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3
crypto/ctr.c
View file

@ -65,8 +65,7 @@ static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
unsigned int nbytes = walk->nbytes;
crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
crypto_xor(keystream, src, nbytes);
memcpy(dst, keystream, nbytes);
crypto_xor_cpy(dst, keystream, src, nbytes);
crypto_inc(ctrblk, bsize);
}