1*e96cb950SEric Biggers /* SPDX-License-Identifier: GPL-2.0-or-later */
2*e96cb950SEric Biggers /*
3*e96cb950SEric Biggers * SHA-256 Secure Hash Algorithm, SPE optimized
4*e96cb950SEric Biggers *
5*e96cb950SEric Biggers * Based on generic implementation. The assembler module takes care
6*e96cb950SEric Biggers * about the SPE registers so it can run from interrupt context.
7*e96cb950SEric Biggers *
8*e96cb950SEric Biggers * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
9*e96cb950SEric Biggers */
10*e96cb950SEric Biggers
11*e96cb950SEric Biggers #include <asm/switch_to.h>
12*e96cb950SEric Biggers #include <linux/preempt.h>
13*e96cb950SEric Biggers
14*e96cb950SEric Biggers /*
15*e96cb950SEric Biggers * MAX_BYTES defines the number of bytes that are allowed to be processed
16*e96cb950SEric Biggers * between preempt_disable() and preempt_enable(). SHA256 takes ~2,000
17*e96cb950SEric Biggers * operations per 64 bytes. e500 cores can issue two arithmetic instructions
18*e96cb950SEric Biggers * per clock cycle using one 32/64 bit unit (SU1) and one 32 bit unit (SU2).
19*e96cb950SEric Biggers * Thus 1KB of input data will need an estimated maximum of 18,000 cycles.
20*e96cb950SEric Biggers * Headroom for cache misses included. Even with the low end model clocked
21*e96cb950SEric Biggers * at 667 MHz this equals to a critical time window of less than 27us.
22*e96cb950SEric Biggers *
23*e96cb950SEric Biggers */
24*e96cb950SEric Biggers #define MAX_BYTES 1024
25*e96cb950SEric Biggers
26*e96cb950SEric Biggers extern void ppc_spe_sha256_transform(struct sha256_block_state *state,
27*e96cb950SEric Biggers const u8 *src, u32 blocks);
28*e96cb950SEric Biggers
spe_begin(void)29*e96cb950SEric Biggers static void spe_begin(void)
30*e96cb950SEric Biggers {
31*e96cb950SEric Biggers /* We just start SPE operations and will save SPE registers later. */
32*e96cb950SEric Biggers preempt_disable();
33*e96cb950SEric Biggers enable_kernel_spe();
34*e96cb950SEric Biggers }
35*e96cb950SEric Biggers
spe_end(void)36*e96cb950SEric Biggers static void spe_end(void)
37*e96cb950SEric Biggers {
38*e96cb950SEric Biggers disable_kernel_spe();
39*e96cb950SEric Biggers /* reenable preemption */
40*e96cb950SEric Biggers preempt_enable();
41*e96cb950SEric Biggers }
42*e96cb950SEric Biggers
sha256_blocks(struct sha256_block_state * state,const u8 * data,size_t nblocks)43*e96cb950SEric Biggers static void sha256_blocks(struct sha256_block_state *state,
44*e96cb950SEric Biggers const u8 *data, size_t nblocks)
45*e96cb950SEric Biggers {
46*e96cb950SEric Biggers do {
47*e96cb950SEric Biggers /* cut input data into smaller blocks */
48*e96cb950SEric Biggers u32 unit = min_t(size_t, nblocks,
49*e96cb950SEric Biggers MAX_BYTES / SHA256_BLOCK_SIZE);
50*e96cb950SEric Biggers
51*e96cb950SEric Biggers spe_begin();
52*e96cb950SEric Biggers ppc_spe_sha256_transform(state, data, unit);
53*e96cb950SEric Biggers spe_end();
54*e96cb950SEric Biggers
55*e96cb950SEric Biggers data += unit * SHA256_BLOCK_SIZE;
56*e96cb950SEric Biggers nblocks -= unit;
57*e96cb950SEric Biggers } while (nblocks);
58*e96cb950SEric Biggers }
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