crypto: arm64/gcm - use inline helper to suppress indirect calls

Introduce an inline wrapper for ghash_do_update() that incorporates
the indirect call to the asm routine that is passed as an argument,
and keep the non-SIMD fallback code out of line. This ensures that
all references to the function pointer are inlined where the address
is taken, removing the need for any indirect calls to begin with.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/ghash-ce-glue.c

@@ -69,17 +69,8 @@ static int ghash_init(struct shash_desc *desc)
 }
 
 static void ghash_do_update(int blocks, u64 dg[], const char *src,
-			    struct ghash_key *key, const char *head,
-			    void (*simd_update)(int blocks, u64 dg[],
-						const char *src,
-						u64 const h[][2],
-						const char *head))
+			    struct ghash_key *key, const char *head)
 {
-	if (likely(crypto_simd_usable() && simd_update)) {
-		kernel_neon_begin();
-		simd_update(blocks, dg, src, key->h, head);
-		kernel_neon_end();
-	} else {
 	be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
 
 	do {
@@ -99,6 +90,22 @@ static void ghash_do_update(int blocks, u64 dg[], const char *src,
 
 	dg[0] = be64_to_cpu(dst.b);
 	dg[1] = be64_to_cpu(dst.a);
+}
+
+static __always_inline
+void ghash_do_simd_update(int blocks, u64 dg[], const char *src,
+			  struct ghash_key *key, const char *head,
+			  void (*simd_update)(int blocks, u64 dg[],
+					      const char *src,
+					      u64 const h[][2],
+					      const char *head))
+{
+	if (likely(crypto_simd_usable())) {
+		kernel_neon_begin();
+		simd_update(blocks, dg, src, key->h, head);
+		kernel_neon_end();
+	} else {
+		ghash_do_update(blocks, dg, src, key, head);
 	}
 }
 
@@ -131,7 +138,7 @@ static int ghash_update(struct shash_desc *desc, const u8 *src,
 		do {
 			int chunk = min(blocks, MAX_BLOCKS);
 
-			ghash_do_update(chunk, ctx->digest, src, key,
+			ghash_do_simd_update(chunk, ctx->digest, src, key,
 					     partial ? ctx->buf : NULL,
 					     pmull_ghash_update_p8);
 
@@ -155,7 +162,7 @@ static int ghash_final(struct shash_desc *desc, u8 *dst)
 
 		memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
 
-		ghash_do_update(1, ctx->digest, ctx->buf, key, NULL,
+		ghash_do_simd_update(1, ctx->digest, ctx->buf, key, NULL,
 				     pmull_ghash_update_p8);
 	}
 	put_unaligned_be64(ctx->digest[1], dst);
@@ -280,7 +287,7 @@ static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
 	if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
 		int blocks = count / GHASH_BLOCK_SIZE;
 
-		ghash_do_update(blocks, dg, src, &ctx->ghash_key,
+		ghash_do_simd_update(blocks, dg, src, &ctx->ghash_key,
 				     *buf_count ? buf : NULL,
 				     pmull_ghash_update_p64);
 
@@ -326,7 +333,7 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[])
 
 	if (buf_count) {
 		memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
-		ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL,
+		ghash_do_simd_update(1, dg, buf, &ctx->ghash_key, NULL,
 				     pmull_ghash_update_p64);
 	}
 }
@@ -403,7 +410,7 @@ static int gcm_encrypt(struct aead_request *req)
 			} while (--remaining > 0);
 
 			ghash_do_update(blocks, dg, walk.dst.virt.addr,
-					&ctx->ghash_key, NULL, NULL);
+					&ctx->ghash_key, NULL);
 
 			err = skcipher_walk_done(&walk,
 						 walk.nbytes % AES_BLOCK_SIZE);
@@ -422,7 +429,7 @@ static int gcm_encrypt(struct aead_request *req)
 
 		tag = (u8 *)&lengths;
 		ghash_do_update(1, dg, tag, &ctx->ghash_key,
-				walk.nbytes ? buf : NULL, NULL);
+				walk.nbytes ? buf : NULL);
 
 		if (walk.nbytes)
 			err = skcipher_walk_done(&walk, 0);
@@ -507,7 +514,7 @@ static int gcm_decrypt(struct aead_request *req)
 			u8 *dst = walk.dst.virt.addr;
 
 			ghash_do_update(blocks, dg, walk.src.virt.addr,
-					&ctx->ghash_key, NULL, NULL);
+					&ctx->ghash_key, NULL);
 
 			do {
 				aes_encrypt(&ctx->aes_key, buf, iv);
@@ -530,7 +537,7 @@ static int gcm_decrypt(struct aead_request *req)
 
 		tag = (u8 *)&lengths;
 		ghash_do_update(1, dg, tag, &ctx->ghash_key,
-				walk.nbytes ? buf : NULL, NULL);
+				walk.nbytes ? buf : NULL);
 
 		if (walk.nbytes) {
 			aes_encrypt(&ctx->aes_key, buf, iv);