[v1,2/3] SHA256 for PPC/SPE - glue

diff --git a/arch/powerpc/crypto/sha256_spe_glue.c b/arch/powerpc/crypto/sha256_spe_glue.c
new file mode 100644
index 0000000..02e88b2
--- /dev/null
+++ b/arch/powerpc/crypto/sha256_spe_glue.c
@@ -0,0 +1,291 @@ 
+/*
+ * Glue code for SHA-256 implementation for SPE instructions (PPC)
+ *
+ * Based on generic implementation.
+ *
+ * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include <crypto/internal/hash.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/cryptohash.h>
+#include <linux/types.h>
+#include <crypto/sha.h>
+#include <asm/byteorder.h>
+#include <asm/switch_to.h>
+#include <linux/hardirq.h>
+
+/*
+ * MAX_BYTES defines the number of bytes that are allowed to be processed
+ * between preempt_disable() and preempt_enable(). SHA256 takes ~2,000
+ * operations per 64 bytes. e500 cores can issue two arithmetic instructions
+ * per clock cycle using one 32/64 bit unit (SU1) and one 32 bit unit (SU2).
+ * Thus 1KB of input data will need an estimated maximum of 18,000 cycles.
+ * Headroom for cache misses included. Even with the low end model clocked
+ * at 667 MHz this equals to a critical time window of less than 27us.
+ *
+ */
+#define MAX_BYTES 1024
+
+extern void ppc_spe_sha256_transform(u32 *state, const u8 *src, u32 blocks);
+
+static bool spe_usable(void)
+{
+	/* SPE instructions not allowed in interrupt context */
+	return !in_interrupt();
+}
+
+static void spe_begin(void)
+{
+	/* disable preemption and save SPE registers if required */
+	preempt_disable();
+	enable_kernel_spe();
+}
+
+static void spe_end(void)
+{
+	/* reenable preemption */
+	preempt_enable();
+}
+
+static inline void ppc_sha256_clear_context(struct sha256_state *sctx)
+{
+	int count = sizeof(struct sha256_state) >> 2;
+	u32 *ptr = (u32 *)sctx;
+
+	/* make sure we can clear the fast way */
+	BUILD_BUG_ON(sizeof(struct sha256_state) % 4);
+	do { *ptr++ = 0; } while (--count);
+}
+
+static int ppc_spe_sha256_init(struct shash_desc *desc)
+{
+	struct sha256_state *sctx = shash_desc_ctx(desc);
+
+	sctx->state[0] = SHA256_H0;
+	sctx->state[1] = SHA256_H1;
+	sctx->state[2] = SHA256_H2;
+	sctx->state[3] = SHA256_H3;
+	sctx->state[4] = SHA256_H4;
+	sctx->state[5] = SHA256_H5;
+	sctx->state[6] = SHA256_H6;
+	sctx->state[7] = SHA256_H7;
+	sctx->count = 0;
+
+	return 0;
+}
+
+static int ppc_spe_sha224_init(struct shash_desc *desc)
+{
+	struct sha256_state *sctx = shash_desc_ctx(desc);
+
+	sctx->state[0] = SHA224_H0;
+	sctx->state[1] = SHA224_H1;
+	sctx->state[2] = SHA224_H2;
+	sctx->state[3] = SHA224_H3;
+	sctx->state[4] = SHA224_H4;
+	sctx->state[5] = SHA224_H5;
+	sctx->state[6] = SHA224_H6;
+	sctx->state[7] = SHA224_H7;
+	sctx->count = 0;
+
+	return 0;
+}
+
+static int ppc_spe_sha256_update(struct shash_desc *desc, const u8 *data,
+			unsigned int len)
+{
+	struct sha256_state *sctx = shash_desc_ctx(desc);
+	const unsigned int offset = sctx->count & 0x3f;
+	const unsigned int avail = 64 - offset;
+	unsigned int bytes;
+	const u8 *src = data;
+
+	if (avail > len) {
+		sctx->count += len;
+		memcpy((char *)sctx->buf + offset, src, len);
+		return 0;
+	}
+
+	if (!spe_usable()) {
+		/* call generic module */
+		return crypto_sha256_update(desc, data, len);
+	}
+
+	sctx->count += len;
+
+	if (offset) {
+		memcpy((char *)sctx->buf + offset, src, avail);
+
+		spe_begin();
+		ppc_spe_sha256_transform(sctx->state, (const u8 *)sctx->buf, 1);
+		spe_end();
+
+		len -= avail;
+		src += avail;
+	}
+
+	while (len > 63) {
+		bytes = (len > MAX_BYTES) ? MAX_BYTES : len;
+		bytes = bytes & ~0x3f;
+
+		spe_begin();
+		ppc_spe_sha256_transform(sctx->state, src, bytes >> 6);
+		spe_end();
+
+		src += bytes;
+		len -= bytes;
+	};
+
+	memcpy((char *)sctx->buf, src, len);
+	return 0;
+}
+
+static int ppc_spe_sha256_final(struct shash_desc *desc, u8 *out)
+{
+	struct sha256_state *sctx = shash_desc_ctx(desc);
+	const unsigned int offset = sctx->count & 0x3f;
+	char *p = (char *)sctx->buf + offset;
+	int padlen;
+	__be64 bits;
+	__be64 *pbits = (__be64 *)(((char *)&sctx->buf) + 56);
+	__be32 *dst = (__be32 *)out;
+	static const u8 paddata[SHA256_BLOCK_SIZE] = { 0x80, };
+
+	if (!spe_usable()) {
+		/* call generic module */
+		padlen = (offset < 56) ? (56 - offset) : ((64+56) - offset);
+		bits = cpu_to_be64(sctx->count << 3);
+		crypto_sha256_update(desc, paddata, padlen);
+		crypto_sha256_update(desc, (const u8 *)&bits, 8);
+	} else {
+		padlen = 55 - offset;
+		*p++ = 0x80;
+
+		spe_begin();
+
+		if (padlen < 0) {
+			memset(p, 0x00, padlen + sizeof (u64));
+			ppc_spe_sha256_transform(sctx->state, sctx->buf, 1);
+			p = (char *)sctx->buf;
+			padlen = 56;
+		}
+
+		memset(p, 0, padlen);
+		*pbits = cpu_to_be64(sctx->count << 3);
+		ppc_spe_sha256_transform(sctx->state, sctx->buf, 1);
+
+		spe_end();
+	}
+
+	dst[0] = cpu_to_be32(sctx->state[0]);
+	dst[1] = cpu_to_be32(sctx->state[1]);
+	dst[2] = cpu_to_be32(sctx->state[2]);
+	dst[3] = cpu_to_be32(sctx->state[3]);
+	dst[4] = cpu_to_be32(sctx->state[4]);
+	dst[5] = cpu_to_be32(sctx->state[5]);
+	dst[6] = cpu_to_be32(sctx->state[6]);
+	dst[7] = cpu_to_be32(sctx->state[7]);
+
+	ppc_sha256_clear_context(sctx);
+	return 0;
+}
+
+static int ppc_spe_sha224_final(struct shash_desc *desc, u8 *out)
+{
+	u32 D[SHA256_DIGEST_SIZE >> 2];
+	__be32 *dst = (__be32 *)out;
+
+	ppc_spe_sha256_final(desc, (u8 *)D);
+
+	/* avoid bytewise memcpy */
+	dst[0] = D[0];
+	dst[1] = D[1];
+	dst[2] = D[2];
+	dst[3] = D[3];
+	dst[4] = D[4];
+	dst[5] = D[5];
+	dst[6] = D[6];
+
+	/* clear sensitive data */
+	memset(D, 0, SHA256_DIGEST_SIZE);
+	return 0;
+}
+
+static int ppc_spe_sha256_export(struct shash_desc *desc, void *out)
+{
+	struct sha256_state *sctx = shash_desc_ctx(desc);
+
+	memcpy(out, sctx, sizeof(*sctx));
+	return 0;
+}
+
+static int ppc_spe_sha256_import(struct shash_desc *desc, const void *in)
+{
+	struct sha256_state *sctx = shash_desc_ctx(desc);
+
+	memcpy(sctx, in, sizeof(*sctx));
+	return 0;
+}
+
+static struct shash_alg algs[2] = { {
+	.digestsize	=	SHA256_DIGEST_SIZE,
+	.init		=	ppc_spe_sha256_init,
+	.update		=	ppc_spe_sha256_update,
+	.final		=	ppc_spe_sha256_final,
+	.export		=	ppc_spe_sha256_export,
+	.import		=	ppc_spe_sha256_import,
+	.descsize	=	sizeof(struct sha256_state),
+	.statesize	=	sizeof(struct sha256_state),
+	.base		=	{
+		.cra_name	=	"sha256",
+		.cra_driver_name=	"sha256-ppc-spe",
+		.cra_priority	=	200,
+		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
+		.cra_blocksize	=	SHA256_BLOCK_SIZE,
+		.cra_module	=	THIS_MODULE,
+	}
+}, {
+	.digestsize	=	SHA224_DIGEST_SIZE,
+	.init		=	ppc_spe_sha224_init,
+	.update		=	ppc_spe_sha256_update,
+	.final		=	ppc_spe_sha224_final,
+	.export		=	ppc_spe_sha256_export,
+	.import		=	ppc_spe_sha256_import,
+	.descsize	=	sizeof(struct sha256_state),
+	.statesize	=	sizeof(struct sha256_state),
+	.base		=	{
+		.cra_name	=	"sha224",
+		.cra_driver_name=	"sha224-ppc-spe",
+		.cra_priority	=	200,
+		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
+		.cra_blocksize	=	SHA224_BLOCK_SIZE,
+		.cra_module	=	THIS_MODULE,
+	}
+} };
+
+static int __init ppc_spe_sha256_mod_init(void)
+{
+	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
+}
+
+static void __exit ppc_spe_sha256_mod_fini(void)
+{
+	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
+}
+
+module_init(ppc_spe_sha256_mod_init);
+module_exit(ppc_spe_sha256_mod_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SHA256 Secure Hash Algorithm, SPE accelerated");
+
+MODULE_ALIAS("sha256-ppc-spe");