The arm64 kernel will shortly disallow nested kernel mode NEON, so
add a fallback to scalar C code that can be invoked in that case.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm64/crypto/Kconfig | 3 +-
arch/arm64/crypto/ghash-ce-glue.c | 49 ++++++++++++++++----
2 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
index d92293747d63..7d75a363e317 100644
--- a/arch/arm64/crypto/Kconfig
+++ b/arch/arm64/crypto/Kconfig
@@ -28,8 +28,9 @@ config CRYPTO_SHA2_ARM64_CE
config CRYPTO_GHASH_ARM64_CE
tristate "GHASH (for GCM chaining mode) using ARMv8 Crypto Extensions"
- depends on ARM64 && KERNEL_MODE_NEON
+ depends on KERNEL_MODE_NEON
select CRYPTO_HASH
+ select CRYPTO_GF128MUL
config CRYPTO_CRCT10DIF_ARM64_CE
tristate "CRCT10DIF digest algorithm using PMULL instructions"
diff --git a/arch/arm64/crypto/ghash-ce-glue.c b/arch/arm64/crypto/ghash-ce-glue.c
index 833ec1e3f3e9..3e1a778b181a 100644
--- a/arch/arm64/crypto/ghash-ce-glue.c
+++ b/arch/arm64/crypto/ghash-ce-glue.c
@@ -1,7 +1,7 @@
/*
* Accelerated GHASH implementation with ARMv8 PMULL instructions.
*
- * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@xxxxxxxxxx>
+ * Copyright (C) 2014 - 2017 Linaro Ltd. <ard.biesheuvel@xxxxxxxxxx>
*
* 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
@@ -9,7 +9,9 @@
*/
#include <asm/neon.h>
+#include <asm/simd.h>
#include <asm/unaligned.h>
+#include <crypto/gf128mul.h>
#include <crypto/internal/hash.h>
#include <linux/cpufeature.h>
#include <linux/crypto.h>
@@ -25,6 +27,7 @@ MODULE_LICENSE("GPL v2");
struct ghash_key {
u64 a;
u64 b;
+ be128 k;
};
struct ghash_desc_ctx {
@@ -44,6 +47,36 @@ static int ghash_init(struct shash_desc *desc)
return 0;
}
+static void ghash_do_update(int blocks, u64 dg[], const char *src,
+ struct ghash_key *key, const char *head)
+{
+ if (may_use_simd()) {
+ kernel_neon_begin();
+ pmull_ghash_update(blocks, dg, src, key, head);
+ kernel_neon_end();
+ } else {
+ be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
+
+ do {
+ const u8 *in = src;
+
+ if (head) {
+ in = head;
+ blocks++;
+ head = NULL;
+ } else {
+ src += GHASH_BLOCK_SIZE;
+ }
+
+ crypto_xor((u8 *)&dst, in, GHASH_BLOCK_SIZE);
+ gf128mul_lle(&dst, &key->k);
+ } while (--blocks);
+
+ dg[0] = be64_to_cpu(dst.b);
+ dg[1] = be64_to_cpu(dst.a);
+ }
+}
+
static int ghash_update(struct shash_desc *desc, const u8 *src,
unsigned int len)
{
@@ -67,10 +100,9 @@ static int ghash_update(struct shash_desc *desc, const u8 *src,
blocks = len / GHASH_BLOCK_SIZE;
len %= GHASH_BLOCK_SIZE;
- kernel_neon_begin_partial(8);
- pmull_ghash_update(blocks, ctx->digest, src, key,
- partial ? ctx->buf : NULL);
- kernel_neon_end();
+ ghash_do_update(blocks, ctx->digest, src, key,
+ partial ? ctx->buf : NULL);
+
src += blocks * GHASH_BLOCK_SIZE;
partial = 0;
}
@@ -89,9 +121,7 @@ static int ghash_final(struct shash_desc *desc, u8 *dst)
memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
- kernel_neon_begin_partial(8);
- pmull_ghash_update(1, ctx->digest, ctx->buf, key, NULL);
- kernel_neon_end();
+ ghash_do_update(1, ctx->digest, ctx->buf, key, NULL);
}
put_unaligned_be64(ctx->digest[1], dst);
put_unaligned_be64(ctx->digest[0], dst + 8);
@@ -111,6 +141,9 @@ static int ghash_setkey(struct crypto_shash *tfm,
return -EINVAL;
}
+ /* needed for the fallback */
+ memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
+
/* perform multiplication by 'x' in GF(2^128) */
b = get_unaligned_be64(inkey);
a = get_unaligned_be64(inkey + 8);
--
2.7.4
