sha1.h

 1/* SPDX-License-Identifier: GPL-2.0-or-later */
 2/*
 3 * SHA-1 optimized for PowerPC
 4 *
 5 * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
 6 */
 7
 8#include <asm/switch_to.h>
 9#include <linux/preempt.h>
10
11#ifdef CONFIG_SPE
12/*
13 * MAX_BYTES defines the number of bytes that are allowed to be processed
14 * between preempt_disable() and preempt_enable(). SHA1 takes ~1000
15 * operations per 64 bytes. e500 cores can issue two arithmetic instructions
16 * per clock cycle using one 32/64 bit unit (SU1) and one 32 bit unit (SU2).
17 * Thus 2KB of input data will need an estimated maximum of 18,000 cycles.
18 * Headroom for cache misses included. Even with the low end model clocked
19 * at 667 MHz this equals to a critical time window of less than 27us.
20 *
21 */
22#define MAX_BYTES 2048
23
24asmlinkage void ppc_spe_sha1_transform(struct sha1_block_state *state,
25				       const u8 *data, u32 nblocks);
26
27static void spe_begin(void)
28{
29	/* We just start SPE operations and will save SPE registers later. */
30	preempt_disable();
31	enable_kernel_spe();
32}
33
34static void spe_end(void)
35{
36	disable_kernel_spe();
37	/* reenable preemption */
38	preempt_enable();
39}
40
41static void sha1_blocks(struct sha1_block_state *state,
42			const u8 *data, size_t nblocks)
43{
44	do {
45		u32 unit = min_t(size_t, nblocks, MAX_BYTES / SHA1_BLOCK_SIZE);
46
47		spe_begin();
48		ppc_spe_sha1_transform(state, data, unit);
49		spe_end();
50
51		data += unit * SHA1_BLOCK_SIZE;
52		nblocks -= unit;
53	} while (nblocks);
54}
55#else /* CONFIG_SPE */
56asmlinkage void powerpc_sha_transform(struct sha1_block_state *state,
57				      const u8 data[SHA1_BLOCK_SIZE]);
58
59static void sha1_blocks(struct sha1_block_state *state,
60			const u8 *data, size_t nblocks)
61{
62	do {
63		powerpc_sha_transform(state, data);
64		data += SHA1_BLOCK_SIZE;
65	} while (--nblocks);
66}
67#endif /* !CONFIG_SPE */