crypto: ghash-clmulni-intel - use C implementation for setkey()

The GHASH setkey() function uses SSE registers but fails to call
kernel_fpu_begin()/kernel_fpu_end(). Instead of adding these calls, and
then having to deal with the restriction that they cannot be called from
interrupt context, move the setkey() implementation to the C domain.

Note that setkey() does not use any particular SSE features and is not
expected to become a performance bottleneck.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Fixes: 0e1227d356e9b (crypto: ghash - Add PCLMULQDQ accelerated implementation)
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/x86/crypto/ghash-clmulni-intel_asm.S b/arch/x86/crypto/ghash-clmulni-intel_asm.S
index 586f41a..185fad4 100644 (file)
--- a/arch/x86/crypto/ghash-clmulni-intel_asm.S
+++ b/arch/x86/crypto/ghash-clmulni-intel_asm.S
@@ -24,10 +24,6 @@
 .align 16
 .Lbswap_mask:
        .octa 0x000102030405060708090a0b0c0d0e0f
-.Lpoly:
-       .octa 0xc2000000000000000000000000000001
-.Ltwo_one:
-       .octa 0x00000001000000000000000000000001
 
 #define DATA   %xmm0
 #define SHASH  %xmm1
@@ -134,28 +130,3 @@ ENTRY(clmul_ghash_update)
 .Lupdate_just_ret:
        ret
 ENDPROC(clmul_ghash_update)
-
-/*
- * void clmul_ghash_setkey(be128 *shash, const u8 *key);
- *
- * Calculate hash_key << 1 mod poly
- */
-ENTRY(clmul_ghash_setkey)
-       movaps .Lbswap_mask, BSWAP
-       movups (%rsi), %xmm0
-       PSHUFB_XMM BSWAP %xmm0
-       movaps %xmm0, %xmm1
-       psllq $1, %xmm0
-       psrlq $63, %xmm1
-       movaps %xmm1, %xmm2
-       pslldq $8, %xmm1
-       psrldq $8, %xmm2
-       por %xmm1, %xmm0
-       # reduction
-       pshufd $0b00100100, %xmm2, %xmm1
-       pcmpeqd .Ltwo_one, %xmm1
-       pand .Lpoly, %xmm1
-       pxor %xmm1, %xmm0
-       movups %xmm0, (%rdi)
-       ret
-ENDPROC(clmul_ghash_setkey)

diff --git a/arch/x86/crypto/ghash-clmulni-intel_glue.c b/arch/x86/crypto/ghash-clmulni-intel_glue.c
index 6759dd1..d785cf2 100644 (file)
--- a/arch/x86/crypto/ghash-clmulni-intel_glue.c
+++ b/arch/x86/crypto/ghash-clmulni-intel_glue.c
@@ -30,8 +30,6 @@ void clmul_ghash_mul(char *dst, const be128 *shash);
 void clmul_ghash_update(char *dst, const char *src, unsigned int srclen,
                        const be128 *shash);
 
-void clmul_ghash_setkey(be128 *shash, const u8 *key);
-
 struct ghash_async_ctx {
        struct cryptd_ahash *cryptd_tfm;
 };
@@ -58,13 +56,23 @@ static int ghash_setkey(struct crypto_shash *tfm,
                        const u8 *key, unsigned int keylen)
 {
        struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
+       be128 *x = (be128 *)key;
+       u64 a, b;
 
        if (keylen != GHASH_BLOCK_SIZE) {
                crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
                return -EINVAL;
        }
 
-       clmul_ghash_setkey(&ctx->shash, key);
+       /* perform multiplication by 'x' in GF(2^128) */
+       a = be64_to_cpu(x->a);
+       b = be64_to_cpu(x->b);
+
+       ctx->shash.a = (__be64)((b << 1) | (a >> 63));
+       ctx->shash.b = (__be64)((a << 1) | (b >> 63));
+
+       if (a >> 63)
+               ctx->shash.b ^= cpu_to_be64(0xc2);
 
        return 0;
 }