1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * SHA-256 Secure Hash Algorithm, SPE optimized 4 * 5 * Based on generic implementation. The assembler module takes care 6 * about the SPE registers so it can run from interrupt context. 7 * 8 * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de> 9 */ 10 11 #include <asm/switch_to.h> 12 #include <linux/preempt.h> 13 14 /* 15 * MAX_BYTES defines the number of bytes that are allowed to be processed 16 * between preempt_disable() and preempt_enable(). SHA256 takes ~2,000 17 * operations per 64 bytes. e500 cores can issue two arithmetic instructions 18 * per clock cycle using one 32/64 bit unit (SU1) and one 32 bit unit (SU2). 19 * Thus 1KB of input data will need an estimated maximum of 18,000 cycles. 20 * Headroom for cache misses included. Even with the low end model clocked 21 * at 667 MHz this equals to a critical time window of less than 27us. 22 * 23 */ 24 #define MAX_BYTES 1024 25 26 extern void ppc_spe_sha256_transform(struct sha256_block_state *state, 27 const u8 *src, u32 blocks); 28 29 static void spe_begin(void) 30 { 31 /* We just start SPE operations and will save SPE registers later. */ 32 preempt_disable(); 33 enable_kernel_spe(); 34 } 35 36 static void spe_end(void) 37 { 38 disable_kernel_spe(); 39 /* reenable preemption */ 40 preempt_enable(); 41 } 42 43 static void sha256_blocks(struct sha256_block_state *state, 44 const u8 *data, size_t nblocks) 45 { 46 do { 47 /* cut input data into smaller blocks */ 48 u32 unit = min_t(size_t, nblocks, 49 MAX_BYTES / SHA256_BLOCK_SIZE); 50 51 spe_begin(); 52 ppc_spe_sha256_transform(state, data, unit); 53 spe_end(); 54 55 data += unit * SHA256_BLOCK_SIZE; 56 nblocks -= unit; 57 } while (nblocks); 58 } 59