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 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 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 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 } 59