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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* SHA-256 Secure Hash Algorithm, SPE optimized
*
* 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>
*/
#include <asm/switch_to.h>
#include <linux/preempt.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(struct sha256_block_state *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 void sha256_blocks(struct sha256_block_state *state,
const u8 *data, size_t nblocks)
{
do {
/* cut input data into smaller blocks */
u32 unit = min_t(size_t, nblocks,
MAX_BYTES / SHA256_BLOCK_SIZE);
spe_begin();
ppc_spe_sha256_transform(state, data, unit);
spe_end();
data += unit * SHA256_BLOCK_SIZE;
nblocks -= unit;
} while (nblocks);
}
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