[PATCH v7 5/7] crypto: arm64/aes-ccm - remove non-SIMD fallback path

[Ard Biesheuvel]

AES/CCM on arm64 is implemented as a synchronous AEAD, and so it is
guaranteed by the API that it is only invoked in task or softirq
context. Since softirqs are now only handled when the SIMD is not
being used in the task context that was interrupted to service the
softirq, we no longer need a fallback path. Let's remove it.

Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
Reviewed-by: Eric Biggers <ebiggers at google.com>
---
 arch/arm64/crypto/aes-ce-ccm-glue.c | 153 ++++----------------
 1 file changed, 32 insertions(+), 121 deletions(-)

diff --git a/arch/arm64/crypto/aes-ce-ccm-glue.c b/arch/arm64/crypto/aes-ce-ccm-glue.c
index fe9c837ac4b9..c1f221a181a5 100644
--- a/arch/arm64/crypto/aes-ce-ccm-glue.c
+++ b/arch/arm64/crypto/aes-ce-ccm-glue.c
@@ -6,12 +6,10 @@
  */
 
 #include <asm/neon.h>
-#include <asm/simd.h>
 #include <asm/unaligned.h>
 #include <crypto/aes.h>
 #include <crypto/scatterwalk.h>
 #include <crypto/internal/aead.h>
-#include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/module.h>
 
@@ -99,36 +97,10 @@ static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
 static void ccm_update_mac(struct crypto_aes_ctx *key, u8 mac[], u8 const in[],
 			   u32 abytes, u32 *macp)
 {
-	if (crypto_simd_usable()) {
-		kernel_neon_begin();
-		ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc,
-				     num_rounds(key));
-		kernel_neon_end();
-	} else {
-		if (*macp > 0 && *macp < AES_BLOCK_SIZE) {
-			int added = min(abytes, AES_BLOCK_SIZE - *macp);
-
-			crypto_xor(&mac[*macp], in, added);
-
-			*macp += added;
-			in += added;
-			abytes -= added;
-		}
-
-		while (abytes >= AES_BLOCK_SIZE) {
-			aes_encrypt(key, mac, mac);
-			crypto_xor(mac, in, AES_BLOCK_SIZE);
-
-			in += AES_BLOCK_SIZE;
-			abytes -= AES_BLOCK_SIZE;
-		}
-
-		if (abytes > 0) {
-			aes_encrypt(key, mac, mac);
-			crypto_xor(mac, in, abytes);
-			*macp = abytes;
-		}
-	}
+	kernel_neon_begin();
+	ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc,
+			     num_rounds(key));
+	kernel_neon_end();
 }
 
 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
@@ -172,54 +144,6 @@ static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
 	} while (len);
 }
 
-static int ccm_crypt_fallback(struct skcipher_walk *walk, u8 mac[], u8 iv0[],
-			      struct crypto_aes_ctx *ctx, bool enc)
-{
-	u8 buf[AES_BLOCK_SIZE];
-	int err = 0;
-
-	while (walk->nbytes) {
-		int blocks = walk->nbytes / AES_BLOCK_SIZE;
-		u32 tail = walk->nbytes % AES_BLOCK_SIZE;
-		u8 *dst = walk->dst.virt.addr;
-		u8 *src = walk->src.virt.addr;
-		u32 nbytes = walk->nbytes;
-
-		if (nbytes == walk->total && tail > 0) {
-			blocks++;
-			tail = 0;
-		}
-
-		do {
-			u32 bsize = AES_BLOCK_SIZE;
-
-			if (nbytes < AES_BLOCK_SIZE)
-				bsize = nbytes;
-
-			crypto_inc(walk->iv, AES_BLOCK_SIZE);
-			aes_encrypt(ctx, buf, walk->iv);
-			aes_encrypt(ctx, mac, mac);
-			if (enc)
-				crypto_xor(mac, src, bsize);
-			crypto_xor_cpy(dst, src, buf, bsize);
-			if (!enc)
-				crypto_xor(mac, dst, bsize);
-			dst += bsize;
-			src += bsize;
-			nbytes -= bsize;
-		} while (--blocks);
-
-		err = skcipher_walk_done(walk, tail);
-	}
-
-	if (!err) {
-		aes_encrypt(ctx, buf, iv0);
-		aes_encrypt(ctx, mac, mac);
-		crypto_xor(mac, buf, AES_BLOCK_SIZE);
-	}
-	return err;
-}
-
 static int ccm_encrypt(struct aead_request *req)
 {
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
@@ -242,30 +166,24 @@ static int ccm_encrypt(struct aead_request *req)
 
 	err = skcipher_walk_aead_encrypt(&walk, req, false);
 
-	if (crypto_simd_usable()) {
-		while (walk.nbytes) {
-			u32 tail = walk.nbytes % AES_BLOCK_SIZE;
+	while (walk.nbytes) {
+		u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 
-			if (walk.nbytes == walk.total)
-				tail = 0;
+		if (walk.nbytes == walk.total)
+			tail = 0;
 
-			kernel_neon_begin();
-			ce_aes_ccm_encrypt(walk.dst.virt.addr,
-					   walk.src.virt.addr,
-					   walk.nbytes - tail, ctx->key_enc,
-					   num_rounds(ctx), mac, walk.iv);
-			kernel_neon_end();
+		kernel_neon_begin();
+		ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
+				   walk.nbytes - tail, ctx->key_enc,
+				   num_rounds(ctx), mac, walk.iv);
+		kernel_neon_end();
 
-			err = skcipher_walk_done(&walk, tail);
-		}
-		if (!err) {
-			kernel_neon_begin();
-			ce_aes_ccm_final(mac, buf, ctx->key_enc,
-					 num_rounds(ctx));
-			kernel_neon_end();
-		}
-	} else {
-		err = ccm_crypt_fallback(&walk, mac, buf, ctx, true);
+		err = skcipher_walk_done(&walk, tail);
+	}
+	if (!err) {
+		kernel_neon_begin();
+		ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
+		kernel_neon_end();
 	}
 	if (err)
 		return err;
@@ -300,32 +218,25 @@ static int ccm_decrypt(struct aead_request *req)
 
 	err = skcipher_walk_aead_decrypt(&walk, req, false);
 
-	if (crypto_simd_usable()) {
-		while (walk.nbytes) {
-			u32 tail = walk.nbytes % AES_BLOCK_SIZE;
+	while (walk.nbytes) {
+		u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 
-			if (walk.nbytes == walk.total)
-				tail = 0;
+		if (walk.nbytes == walk.total)
+			tail = 0;
 
-			kernel_neon_begin();
-			ce_aes_ccm_decrypt(walk.dst.virt.addr,
-					   walk.src.virt.addr,
+		kernel_neon_begin();
+		ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
 					   walk.nbytes - tail, ctx->key_enc,
 					   num_rounds(ctx), mac, walk.iv);
-			kernel_neon_end();
+		kernel_neon_end();
 
-			err = skcipher_walk_done(&walk, tail);
-		}
-		if (!err) {
-			kernel_neon_begin();
-			ce_aes_ccm_final(mac, buf, ctx->key_enc,
-					 num_rounds(ctx));
-			kernel_neon_end();
-		}
-	} else {
-		err = ccm_crypt_fallback(&walk, mac, buf, ctx, false);
+		err = skcipher_walk_done(&walk, tail);
+	}
+	if (!err) {
+		kernel_neon_begin();
+		ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
+		kernel_neon_end();
 	}
-
 	if (err)
 		return err;
 
-- 
2.30.2