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/*
* Glue code for SHA-256 implementation for SPE instructions (PPC)
*
* Based on generic implementation. The assembler module takes care
* about the SPE registers so it can run from interrupt context.
*
* 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 void spe_begin(void)
{
/* We just start SPE operations and will save SPE registers later. */
preempt_disable();
enable_kernel_spe();
}
static void spe_end(void)
{
disable_kernel_spe();
/* 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;
}
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) {
/* cut input data into smaller blocks */
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 *pbits = (__be64 *)(((char *)&sctx->buf) + 56);
__be32 *dst = (__be32 *)out;
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 */
memzero_explicit(D, 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 = 300,
.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 = 300,
.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("SHA-224 and SHA-256 Secure Hash Algorithm, SPE optimized");
MODULE_ALIAS_CRYPTO("sha224");
MODULE_ALIAS_CRYPTO("sha224-ppc-spe");
MODULE_ALIAS_CRYPTO("sha256");
MODULE_ALIAS_CRYPTO("sha256-ppc-spe");
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