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>

2 files changed, 11 insertions, 32 deletions

diff --git a/arch/x86/crypto/ghash-clmulni-intel_asm.S b/arch/x86/crypto/ghash-clmulni-intel_asm.S
index 586f41aac361..185fad49d86f 100644
--- 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 6759dd1135be..d785cf2c529c 100644
--- 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;
 }