diff mbox

[5/5] arm64: add Crypto Extensions based synchronous core AES cipher

Message ID 1391014246-9715-6-git-send-email-ard.biesheuvel@linaro.org
State New
Headers show

Commit Message

Ard Biesheuvel Jan. 29, 2014, 4:50 p.m. UTC 
This implements the core AES cipher using the Crypto Extensions,
using only NEON registers q0 and q1.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/arm64/Makefile               |   1 +
 arch/arm64/crypto/Makefile        |  13 +++++
 arch/arm64/crypto/aes-ce-cipher.c | 103 ++++++++++++++++++++++++++++++++++++++
 crypto/Kconfig                    |   6 +++
 4 files changed, 123 insertions(+)
 create mode 100644 arch/arm64/crypto/Makefile
 create mode 100644 arch/arm64/crypto/aes-ce-cipher.c

Comments

Ard Biesheuvel Jan. 30, 2014, 7:20 p.m. UTC | #1 
On 30 January 2014 19:56, Will Deacon <will.deacon@arm.com> wrote:
> Hi Ard,
>
> On Wed, Jan 29, 2014 at 04:50:46PM +0000, Ard Biesheuvel wrote:
>> diff --git a/arch/arm64/crypto/aes-ce-cipher.c b/arch/arm64/crypto/aes-ce-cipher.c
>> new file mode 100644
>> index 000000000000..b5a5d5d6e4b8
>> --- /dev/null
>> +++ b/arch/arm64/crypto/aes-ce-cipher.c
>> @@ -0,0 +1,103 @@
>> +/*
>> + * linux/arch/arm64/crypto/aes-ce-cipher.c
>> + *
>> + * Copyright (C) 2013 Linaro Ltd <ard.biesheuvel@linaro.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#include <asm/neon.h>
>> +#include <crypto/aes.h>
>> +#include <linux/crypto.h>
>> +#include <linux/module.h>
>> +#include <linux/cpufeature.h>
>> +
>> +MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
>> +MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
>> +MODULE_LICENSE("GPL");
>> +
>> +static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
>> +{
>> +     struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
>> +     u32 rounds = 6 + ctx->key_length / 4;
>
> Can you document these constants please?
>

Sure.

>> +
>> +     kernel_neon_begin();
>> +
>> +     __asm__("       ld1             {v0.16b}, [%[in]]               ;"
>> +             "       ld1             {v1.16b}, [%[key]], #16         ;"
>> +             "0:     aese            v0.16b, v1.16b                  ;"
>> +             "       subs            %[rounds], %[rounds], #1        ;"
>> +             "       ld1             {v1.16b}, [%[key]], #16         ;"
>> +             "       beq             1f                              ;"
>> +             "       aesmc           v0.16b, v0.16b                  ;"
>> +             "       b               0b                              ;"
>> +             "1:     eor             v0.16b, v0.16b, v1.16b          ;"
>> +             "       st1             {v0.16b}, [%[out]]              ;"
>> +     : :
>> +             [out]           "r"(dst),
>> +             [in]            "r"(src),
>> +             [rounds]        "r"(rounds),
>> +             [key]           "r"(ctx->key_enc)
>> +     :                       "cc");
>
> You probably need a memory output to stop this being re-ordered by the
> compiler. Can GCC not generate the addressing modes you need directly,
> allowing you to avoid moving everything into registers?
>

Would a memory clobber work as well?

Re addressing modes: I would prefer to explicitly use v0 and v1, I
have another patch pending that allows partial saves/restores of the
NEON register file when called from interrupt context. I suppose I
could use 'register asm("v0")' or something like that, but that won't
make it any prettier.

>
>> +     kernel_neon_end();
>> +}
>> +
>> +static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
>> +{
>> +     struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
>> +     u32 rounds = 6 + ctx->key_length / 4;
>> +
>> +     kernel_neon_begin();
>> +
>> +     __asm__("       ld1             {v0.16b}, [%[in]]               ;"
>> +             "       ld1             {v1.16b}, [%[key]], #16         ;"
>> +             "0:     aesd            v0.16b, v1.16b                  ;"
>> +             "       ld1             {v1.16b}, [%[key]], #16         ;"
>> +             "       subs            %[rounds], %[rounds], #1        ;"
>> +             "       beq             1f                              ;"
>> +             "       aesimc          v0.16b, v0.16b                  ;"
>> +             "       b               0b                              ;"
>> +             "1:     eor             v0.16b, v0.16b, v1.16b          ;"
>> +             "       st1             {v0.16b}, [%[out]]              ;"
>> +     : :
>> +             [out]           "r"(dst),
>> +             [in]            "r"(src),
>> +             [rounds]        "r"(rounds),
>> +             [key]           "r"(ctx->key_dec)
>> +     :                       "cc");
>
> Same comments here.
>
> FWIW: I spoke to the guy at ARM who designed the crypto instructions and he
> reckons your code works :)
>

Good!

Care to comment on the rest of the series?

Cheers.
Ard.
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diff mbox

Patch

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 2fceb71ac3b7..8185a913c5ed 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -45,6 +45,7 @@  export	TEXT_OFFSET GZFLAGS
 core-y		+= arch/arm64/kernel/ arch/arm64/mm/
 core-$(CONFIG_KVM) += arch/arm64/kvm/
 core-$(CONFIG_XEN) += arch/arm64/xen/
+core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
 libs-y		:= arch/arm64/lib/ $(libs-y)
 libs-y		+= $(LIBGCC)
 
diff --git a/arch/arm64/crypto/Makefile b/arch/arm64/crypto/Makefile
new file mode 100644
index 000000000000..ac58945c50b3
--- /dev/null
+++ b/arch/arm64/crypto/Makefile
@@ -0,0 +1,13 @@ 
+#
+# linux/arch/arm64/crypto/Makefile
+#
+# Copyright (C) 2013 Linaro Ltd <ard.biesheuvel@linaro.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+
+obj-$(CONFIG_CRYPTO_AES_ARM64_CE) += aes-ce-cipher.o
+
+CFLAGS_aes-ce-cipher.o += -march=armv8-a+crypto
diff --git a/arch/arm64/crypto/aes-ce-cipher.c b/arch/arm64/crypto/aes-ce-cipher.c
new file mode 100644
index 000000000000..b5a5d5d6e4b8
--- /dev/null
+++ b/arch/arm64/crypto/aes-ce-cipher.c
@@ -0,0 +1,103 @@ 
+/*
+ * linux/arch/arm64/crypto/aes-ce-cipher.c
+ *
+ * Copyright (C) 2013 Linaro Ltd <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/neon.h>
+#include <crypto/aes.h>
+#include <linux/crypto.h>
+#include <linux/module.h>
+#include <linux/cpufeature.h>
+
+MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
+MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
+MODULE_LICENSE("GPL");
+
+static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
+{
+	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
+	u32 rounds = 6 + ctx->key_length / 4;
+
+	kernel_neon_begin();
+
+	__asm__("	ld1		{v0.16b}, [%[in]]		;"
+		"	ld1		{v1.16b}, [%[key]], #16		;"
+		"0:	aese		v0.16b, v1.16b			;"
+		"	subs		%[rounds], %[rounds], #1	;"
+		"	ld1		{v1.16b}, [%[key]], #16		;"
+		"	beq		1f				;"
+		"	aesmc		v0.16b, v0.16b			;"
+		"	b		0b				;"
+		"1:	eor		v0.16b, v0.16b, v1.16b		;"
+		"	st1		{v0.16b}, [%[out]]		;"
+	: :
+		[out]		"r"(dst),
+		[in]		"r"(src),
+		[rounds]	"r"(rounds),
+		[key]		"r"(ctx->key_enc)
+	:			"cc");
+
+	kernel_neon_end();
+}
+
+static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
+{
+	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
+	u32 rounds = 6 + ctx->key_length / 4;
+
+	kernel_neon_begin();
+
+	__asm__("	ld1		{v0.16b}, [%[in]]		;"
+		"	ld1		{v1.16b}, [%[key]], #16		;"
+		"0:	aesd		v0.16b, v1.16b			;"
+		"	ld1		{v1.16b}, [%[key]], #16		;"
+		"	subs		%[rounds], %[rounds], #1	;"
+		"	beq		1f				;"
+		"	aesimc		v0.16b, v0.16b			;"
+		"	b		0b				;"
+		"1:	eor		v0.16b, v0.16b, v1.16b		;"
+		"	st1		{v0.16b}, [%[out]]		;"
+	: :
+		[out]		"r"(dst),
+		[in]		"r"(src),
+		[rounds]	"r"(rounds),
+		[key]		"r"(ctx->key_dec)
+	:			"cc");
+
+	kernel_neon_end();
+}
+
+static struct crypto_alg aes_alg = {
+	.cra_name		= "aes",
+	.cra_driver_name	= "aes-ce",
+	.cra_priority		= 300,
+	.cra_flags		= CRYPTO_ALG_TYPE_CIPHER,
+	.cra_blocksize		= AES_BLOCK_SIZE,
+	.cra_ctxsize		= sizeof(struct crypto_aes_ctx),
+	.cra_module		= THIS_MODULE,
+	.cra_cipher = {
+		.cia_min_keysize	= AES_MIN_KEY_SIZE,
+		.cia_max_keysize	= AES_MAX_KEY_SIZE,
+		.cia_setkey		= crypto_aes_set_key,
+		.cia_encrypt		= aes_cipher_encrypt,
+		.cia_decrypt		= aes_cipher_decrypt
+	}
+};
+
+static int __init aes_mod_init(void)
+{
+	return crypto_register_alg(&aes_alg);
+}
+
+static void __exit aes_mod_exit(void)
+{
+	crypto_unregister_alg(&aes_alg);
+}
+
+module_cpu_feature_match(AES, aes_mod_init);
+module_exit(aes_mod_exit);
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 7bcb70d216e1..f1d98bc346b6 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -791,6 +791,12 @@  config CRYPTO_AES_ARM_BS
 	  This implementation does not rely on any lookup tables so it is
 	  believed to be invulnerable to cache timing attacks.
 
+config CRYPTO_AES_ARM64_CE
+	tristate "Synchronous AES cipher using ARMv8 Crypto Extensions"
+	depends on ARM64 && KERNEL_MODE_NEON
+	select CRYPTO_ALGAPI
+	select CRYPTO_AES
+
 config CRYPTO_ANUBIS
 	tristate "Anubis cipher algorithm"
 	select CRYPTO_ALGAPI