target/linux/generic/backport-5.4/080-wireguard-0005-crypto-arm64-chacha-depend-on-generic-chacha-library.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Ard Biesheuvel <ardb@kernel.org>
   3 Date: Fri, 8 Nov 2019 13:22:11 +0100
   4 Subject: [PATCH] crypto: arm64/chacha - depend on generic chacha library
   5  instead of crypto driver
   6
   7 commit c77da4867cbb7841177275dbb250f5c09679fae4 upstream.
   8
   9 Depend on the generic ChaCha library routines instead of pulling in the
  10 generic ChaCha skcipher driver, which is more than we need, and makes
  11 managing the dependencies between the generic library, generic driver,
  12 accelerated library and driver more complicated.
  13
  14 While at it, drop the logic to prefer the scalar code on short inputs.
  15 Turning the NEON on and off is cheap these days, and one major use case
  16 for ChaCha20 is ChaCha20-Poly1305, which is guaranteed to hit the scalar
  17 path upon every invocation  (when doing the Poly1305 nonce generation)
  18
  19 Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
  20 Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
  21 Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
  22 ---
  23  arch/arm64/crypto/Kconfig            |  2 +-
  24  arch/arm64/crypto/chacha-neon-glue.c | 40 +++++++++++++++-------------
  25  2 files changed, 23 insertions(+), 19 deletions(-)
  26
  27 --- a/arch/arm64/crypto/Kconfig
  28 +++ b/arch/arm64/crypto/Kconfig
  29 @@ -103,7 +103,7 @@ config CRYPTO_CHACHA20_NEON
  30         tristate "ChaCha20, XChaCha20, and XChaCha12 stream ciphers using NEON instructions"
  31         depends on KERNEL_MODE_NEON
  32         select CRYPTO_BLKCIPHER
  33 -       select CRYPTO_CHACHA20
  34 +       select CRYPTO_LIB_CHACHA_GENERIC
  35
  36  config CRYPTO_NHPOLY1305_NEON
  37         tristate "NHPoly1305 hash function using NEON instructions (for Adiantum)"
  38 --- a/arch/arm64/crypto/chacha-neon-glue.c
  39 +++ b/arch/arm64/crypto/chacha-neon-glue.c
  40 @@ -68,7 +68,7 @@ static int chacha_neon_stream_xor(struct
  41
  42         err = skcipher_walk_virt(&walk, req, false);
  43
  44 -       crypto_chacha_init(state, ctx, iv);
  45 +       chacha_init_generic(state, ctx->key, iv);
  46
  47         while (walk.nbytes > 0) {
  48                 unsigned int nbytes = walk.nbytes;
  49 @@ -76,10 +76,16 @@ static int chacha_neon_stream_xor(struct
  50                 if (nbytes < walk.total)
  51                         nbytes = rounddown(nbytes, walk.stride);
  52
  53 -               kernel_neon_begin();
  54 -               chacha_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
  55 -                             nbytes, ctx->nrounds);
  56 -               kernel_neon_end();
  57 +               if (!crypto_simd_usable()) {
  58 +                       chacha_crypt_generic(state, walk.dst.virt.addr,
  59 +                                            walk.src.virt.addr, nbytes,
  60 +                                            ctx->nrounds);
  61 +               } else {
  62 +                       kernel_neon_begin();
  63 +                       chacha_doneon(state, walk.dst.virt.addr,
  64 +                                     walk.src.virt.addr, nbytes, ctx->nrounds);
  65 +                       kernel_neon_end();
  66 +               }
  67                 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
  68         }
  69
  70 @@ -91,9 +97,6 @@ static int chacha_neon(struct skcipher_r
  71         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  72         struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
  73
  74 -       if (req->cryptlen <= CHACHA_BLOCK_SIZE || !crypto_simd_usable())
  75 -               return crypto_chacha_crypt(req);
  76 -
  77         return chacha_neon_stream_xor(req, ctx, req->iv);
  78  }
  79
  80 @@ -105,14 +108,15 @@ static int xchacha_neon(struct skcipher_
  81         u32 state[16];
  82         u8 real_iv[16];
  83
  84 -       if (req->cryptlen <= CHACHA_BLOCK_SIZE || !crypto_simd_usable())
  85 -               return crypto_xchacha_crypt(req);
  86 -
  87 -       crypto_chacha_init(state, ctx, req->iv);
  88 +       chacha_init_generic(state, ctx->key, req->iv);
  89
  90 -       kernel_neon_begin();
  91 -       hchacha_block_neon(state, subctx.key, ctx->nrounds);
  92 -       kernel_neon_end();
  93 +       if (crypto_simd_usable()) {
  94 +               kernel_neon_begin();
  95 +               hchacha_block_neon(state, subctx.key, ctx->nrounds);
  96 +               kernel_neon_end();
  97 +       } else {
  98 +               hchacha_block_generic(state, subctx.key, ctx->nrounds);
  99 +       }
 100         subctx.nrounds = ctx->nrounds;
 101
 102         memcpy(&real_iv[0], req->iv + 24, 8);
 103 @@ -134,7 +138,7 @@ static struct skcipher_alg algs[] = {
 104                 .ivsize                 = CHACHA_IV_SIZE,
 105                 .chunksize              = CHACHA_BLOCK_SIZE,
 106                 .walksize               = 5 * CHACHA_BLOCK_SIZE,
 107 -               .setkey                 = crypto_chacha20_setkey,
 108 +               .setkey                 = chacha20_setkey,
 109                 .encrypt                = chacha_neon,
 110                 .decrypt                = chacha_neon,
 111         }, {
 112 @@ -150,7 +154,7 @@ static struct skcipher_alg algs[] = {
 113                 .ivsize                 = XCHACHA_IV_SIZE,
 114                 .chunksize              = CHACHA_BLOCK_SIZE,
 115                 .walksize               = 5 * CHACHA_BLOCK_SIZE,
 116 -               .setkey                 = crypto_chacha20_setkey,
 117 +               .setkey                 = chacha20_setkey,
 118                 .encrypt                = xchacha_neon,
 119                 .decrypt                = xchacha_neon,
 120         }, {
 121 @@ -166,7 +170,7 @@ static struct skcipher_alg algs[] = {
 122                 .ivsize                 = XCHACHA_IV_SIZE,
 123                 .chunksize              = CHACHA_BLOCK_SIZE,
 124                 .walksize               = 5 * CHACHA_BLOCK_SIZE,
 125 -               .setkey                 = crypto_chacha12_setkey,
 126 +               .setkey                 = chacha12_setkey,
 127                 .encrypt                = xchacha_neon,
 128                 .decrypt                = xchacha_neon,
 129         }