crypto: arm64/aes-ce-cipher: add non-SIMD generic fallback

The arm64 kernel will shortly disallow nested kernel mode NEON, so
add a fallback to scalar code that can be invoked in that case.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Author: Ard Biesheuvel

arch/arm64/crypto/Kconfig

@@ -52,6 +52,7 @@ config CRYPTO_AES_ARM64_CE
 	tristate "AES core cipher using ARMv8 Crypto Extensions"
 	depends on ARM64 && KERNEL_MODE_NEON
 	select CRYPTO_ALGAPI
+	select CRYPTO_AES_ARM64
 
 config CRYPTO_AES_ARM64_CE_CCM
 	tristate "AES in CCM mode using ARMv8 Crypto Extensions"

arch/arm64/crypto/aes-ce-cipher.c

@@ -9,6 +9,7 @@
  */
 
 #include <asm/neon.h>
+#include <asm/simd.h>
 #include <asm/unaligned.h>
 #include <crypto/aes.h>
 #include <linux/cpufeature.h>
@@ -21,6 +22,9 @@ MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 MODULE_LICENSE("GPL v2");
 
+asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
+asmlinkage void __aes_arm64_decrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
+
 struct aes_block {
 	u8 b[AES_BLOCK_SIZE];
 };
@@ -45,7 +49,12 @@ static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
 	void *dummy0;
 	int dummy1;
 
-	kernel_neon_begin_partial(4);
+	if (!may_use_simd()) {
+		__aes_arm64_encrypt(ctx->key_enc, dst, src, num_rounds(ctx));
+		return;
+	}
+
+	kernel_neon_begin();
 
 	__asm__("	ld1	{v0.16b}, %[in]			;"
 		"	ld1	{v1.4s}, [%[key]], #16		;"
@@ -90,7 +99,12 @@ static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
 	void *dummy0;
 	int dummy1;
 
-	kernel_neon_begin_partial(4);
+	if (!may_use_simd()) {
+		__aes_arm64_decrypt(ctx->key_dec, dst, src, num_rounds(ctx));
+		return;
+	}
+
+	kernel_neon_begin();
 
 	__asm__("	ld1	{v0.16b}, %[in]			;"
 		"	ld1	{v1.4s}, [%[key]], #16		;"
@@ -170,7 +184,7 @@ int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
 	for (i = 0; i < kwords; i++)
 		ctx->key_enc[i] = get_unaligned_le32(in_key + i * sizeof(u32));
 
-	kernel_neon_begin_partial(2);
+	kernel_neon_begin();
 	for (i = 0; i < sizeof(rcon); i++) {
 		u32 *rki = ctx->key_enc + (i * kwords);
 		u32 *rko = rki + kwords;