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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 */