crypto: Add generic 32-bit carry-less multiply routines

Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
qemu · Sep 15, 2023 · 9a65a57 · 9a65a57
1 parent a2c6734
commit 9a65a57
Show file tree

Hide file tree

Showing 2 changed files with 20 additions and 0 deletions.
diff --git a/crypto/clmul.c b/crypto/clmul.c
@@ -79,3 +79,16 @@ uint64_t clmul_16x2_odd(uint64_t n, uint64_t m)
 {
     return clmul_16x2_even(n >> 16, m >> 16);
 }
+
+uint64_t clmul_32(uint32_t n, uint32_t m32)
+{
+    uint64_t r = 0;
+    uint64_t m = m32;
+
+    for (int i = 0; i < 32; ++i) {
+        r ^= n & 1 ? m : 0;
+        n >>= 1;
+        m <<= 1;
+    }
+    return r;
+}
diff --git a/include/crypto/clmul.h b/include/crypto/clmul.h
@@ -54,4 +54,11 @@ uint64_t clmul_16x2_even(uint64_t, uint64_t);
  */
 uint64_t clmul_16x2_odd(uint64_t, uint64_t);
 
+/**
+ * clmul_32:
+ *
+ * Perform a 32x32->64 carry-less multiply.
+ */
+uint64_t clmul_32(uint32_t, uint32_t);
+
 #endif /* CRYPTO_CLMUL_H */