crypto: Create sm4_subword

Allows sharing of sm4_subword between different targets.

Signed-off-by: Max Chou <max.chou@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Max Chou <max.chou@sifive.com>
Message-ID: <20230711165917.2629866-14-max.chou@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

include/crypto/sm4.h

@@ -3,4 +3,12 @@
 
 extern const uint8_t sm4_sbox[256];
 
+static inline uint32_t sm4_subword(uint32_t word)
+{
+    return sm4_sbox[word & 0xff] |
+           sm4_sbox[(word >> 8) & 0xff] << 8 |
+           sm4_sbox[(word >> 16) & 0xff] << 16 |
+           sm4_sbox[(word >> 24) & 0xff] << 24;
+}
+
 #endif

target/arm/tcg/crypto_helper.c

@@ -614,10 +614,7 @@ static void do_crypto_sm4e(uint64_t *rd, uint64_t *rn, uint64_t *rm)
             CR_ST_WORD(d, (i + 3) % 4) ^
             CR_ST_WORD(n, i);
 
-        t = sm4_sbox[t & 0xff] |
-            sm4_sbox[(t >> 8) & 0xff] << 8 |
-            sm4_sbox[(t >> 16) & 0xff] << 16 |
-            sm4_sbox[(t >> 24) & 0xff] << 24;
+        t = sm4_subword(t);
 
         CR_ST_WORD(d, i) ^= t ^ rol32(t, 2) ^ rol32(t, 10) ^ rol32(t, 18) ^
                             rol32(t, 24);
@@ -651,10 +648,7 @@ static void do_crypto_sm4ekey(uint64_t *rd, uint64_t *rn, uint64_t *rm)
             CR_ST_WORD(d, (i + 3) % 4) ^
             CR_ST_WORD(m, i);
 
-        t = sm4_sbox[t & 0xff] |
-            sm4_sbox[(t >> 8) & 0xff] << 8 |
-            sm4_sbox[(t >> 16) & 0xff] << 16 |
-            sm4_sbox[(t >> 24) & 0xff] << 24;
+        t = sm4_subword(t);
 
         CR_ST_WORD(d, i) ^= t ^ rol32(t, 13) ^ rol32(t, 23);
     }