OVMS3-idf/components/esp32/hwcrypto/sha.c
Angus Gratton 94ed7b8298 hwcrypto sha: Use spinlocks instead of semaphores for small state changes
Significant performance improvement and smaller RAM footprint.
2019-01-23 18:18:13 +08:00

334 lines
9.1 KiB
C

/*
* ESP32 hardware accelerated SHA1/256/512 implementation
* based on mbedTLS FIPS-197 compliant version.
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* Additions Copyright (C) 2016, Espressif Systems (Shanghai) PTE Ltd
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
/*
* The SHA-1 standard was published by NIST in 1993.
*
* http://www.itl.nist.gov/fipspubs/fip180-1.htm
*/
#include <string.h>
#include <stdio.h>
#include <byteswap.h>
#include <assert.h>
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "hwcrypto/sha.h"
#include "rom/ets_sys.h"
#include "soc/dport_reg.h"
#include "soc/hwcrypto_reg.h"
#include "driver/periph_ctrl.h"
inline static uint32_t SHA_LOAD_REG(esp_sha_type sha_type) {
return SHA_1_LOAD_REG + sha_type * 0x10;
}
inline static uint32_t SHA_BUSY_REG(esp_sha_type sha_type) {
return SHA_1_BUSY_REG + sha_type * 0x10;
}
inline static uint32_t SHA_START_REG(esp_sha_type sha_type) {
return SHA_1_START_REG + sha_type * 0x10;
}
inline static uint32_t SHA_CONTINUE_REG(esp_sha_type sha_type) {
return SHA_1_CONTINUE_REG + sha_type * 0x10;
}
/* Single spinlock for SHA engine memory block
*/
static portMUX_TYPE memory_block_lock = portMUX_INITIALIZER_UNLOCKED;
/* Binary semaphore managing the state of each concurrent SHA engine.
Available = noone is using this SHA engine
Taken = a SHA session is running on this SHA engine
Indexes:
0 = SHA1
1 = SHA2_256
2 = SHA2_384 or SHA2_512
*/
static SemaphoreHandle_t engine_states[3];
static uint8_t engines_in_use;
/* Spinlock for engines_in_use counter
*/
static portMUX_TYPE engines_in_use_lock = portMUX_INITIALIZER_UNLOCKED;
/* Index into the engine_states array */
inline static size_t sha_engine_index(esp_sha_type type) {
switch(type) {
case SHA1:
return 0;
case SHA2_256:
return 1;
default:
return 2;
}
}
/* Return digest length (in bytes) for a given SHA type */
inline static size_t sha_length(esp_sha_type type) {
switch(type) {
case SHA1:
return 20;
case SHA2_256:
return 32;
case SHA2_384:
return 48;
case SHA2_512:
return 64;
default:
return 0;
}
}
/* Return block size (in bytes) for a given SHA type */
inline static size_t block_length(esp_sha_type type) {
switch(type) {
case SHA1:
case SHA2_256:
return 64;
case SHA2_384:
case SHA2_512:
return 128;
default:
return 0;
}
}
void esp_sha_lock_memory_block(void)
{
portENTER_CRITICAL(&memory_block_lock);
}
void esp_sha_unlock_memory_block(void)
{
portEXIT_CRITICAL(&memory_block_lock);
}
static SemaphoreHandle_t sha_get_engine_state(esp_sha_type sha_type)
{
unsigned idx = sha_engine_index(sha_type);
volatile SemaphoreHandle_t *engine = &engine_states[idx];
SemaphoreHandle_t result = *engine;
if (result == NULL) {
// Create a new semaphore for 'in use' flag
SemaphoreHandle_t new_engine = xSemaphoreCreateBinary();
assert(new_engine != NULL);
xSemaphoreGive(new_engine); // start available
// try to atomically set the previously NULL *engine to new_engine
uint32_t set_engine = (uint32_t)new_engine;
uxPortCompareSet((volatile uint32_t *)engine, 0, &set_engine);
if (set_engine != 0) { // we lost a race setting *engine
vSemaphoreDelete(new_engine);
}
result = *engine;
}
return result;
}
static bool esp_sha_lock_engine_common(esp_sha_type sha_type, TickType_t ticks_to_wait);
bool esp_sha_try_lock_engine(esp_sha_type sha_type)
{
return esp_sha_lock_engine_common(sha_type, 0);
}
void esp_sha_lock_engine(esp_sha_type sha_type)
{
esp_sha_lock_engine_common(sha_type, portMAX_DELAY);
}
static bool esp_sha_lock_engine_common(esp_sha_type sha_type, TickType_t ticks_to_wait)
{
SemaphoreHandle_t engine_state = sha_get_engine_state(sha_type);
BaseType_t result = xSemaphoreTake(engine_state, ticks_to_wait);
if (result == pdFALSE) {
// failed to take semaphore
return false;
}
portENTER_CRITICAL(&engines_in_use_lock);
if (engines_in_use == 0) {
/* Just locked first engine,
so enable SHA hardware */
periph_module_enable(PERIPH_SHA_MODULE);
DPORT_STALL_OTHER_CPU_START();
ets_sha_enable();
DPORT_STALL_OTHER_CPU_END();
}
engines_in_use++;
assert(engines_in_use <= 3);
portEXIT_CRITICAL(&engines_in_use_lock);
return true;
}
void esp_sha_unlock_engine(esp_sha_type sha_type)
{
SemaphoreHandle_t *engine_state = sha_get_engine_state(sha_type);
portENTER_CRITICAL(&engines_in_use_lock);
engines_in_use--;
if (engines_in_use == 0) {
/* About to release last engine, so
disable SHA hardware */
periph_module_disable(PERIPH_SHA_MODULE);
}
portEXIT_CRITICAL(&engines_in_use_lock);
xSemaphoreGive(engine_state);
}
void esp_sha_wait_idle(void)
{
while(1) {
if(DPORT_REG_READ(SHA_1_BUSY_REG) == 0
&& DPORT_REG_READ(SHA_256_BUSY_REG) == 0
&& DPORT_REG_READ(SHA_384_BUSY_REG) == 0
&& DPORT_REG_READ(SHA_512_BUSY_REG) == 0) {
break;
}
}
}
void esp_sha_read_digest_state(esp_sha_type sha_type, void *digest_state)
{
#ifndef NDEBUG
{
SemaphoreHandle_t *engine_state = sha_get_engine_state(sha_type);
assert(uxSemaphoreGetCount(engine_state) == 0 &&
"SHA engine should be locked" );
}
#endif
// preemptively do this before entering the critical section, then re-check once in it
esp_sha_wait_idle();
esp_sha_lock_memory_block();
esp_sha_wait_idle();
DPORT_REG_WRITE(SHA_LOAD_REG(sha_type), 1);
while(DPORT_REG_READ(SHA_BUSY_REG(sha_type)) == 1) { }
uint32_t *digest_state_words = (uint32_t *)digest_state;
uint32_t *reg_addr_buf = (uint32_t *)(SHA_TEXT_BASE);
if(sha_type == SHA2_384 || sha_type == SHA2_512) {
/* for these ciphers using 64-bit states, swap each pair of words */
DPORT_INTERRUPT_DISABLE(); // Disable interrupt only on current CPU.
for(int i = 0; i < sha_length(sha_type)/4; i += 2) {
digest_state_words[i+1] = DPORT_SEQUENCE_REG_READ((uint32_t)&reg_addr_buf[i]);
digest_state_words[i] = DPORT_SEQUENCE_REG_READ((uint32_t)&reg_addr_buf[i+1]);
}
DPORT_INTERRUPT_RESTORE(); // restore the previous interrupt level
} else {
esp_dport_access_read_buffer(digest_state_words, (uint32_t)&reg_addr_buf[0], sha_length(sha_type)/4);
}
esp_sha_unlock_memory_block();
}
void esp_sha_block(esp_sha_type sha_type, const void *data_block, bool is_first_block)
{
#ifndef NDEBUG
{
SemaphoreHandle_t *engine_state = sha_get_engine_state(sha_type);
assert(uxSemaphoreGetCount(engine_state) == 0 &&
"SHA engine should be locked" );
}
#endif
// preemptively do this before entering the critical section, then re-check once in it
esp_sha_wait_idle();
esp_sha_lock_memory_block();
esp_sha_wait_idle();
/* Fill the data block */
uint32_t *reg_addr_buf = (uint32_t *)(SHA_TEXT_BASE);
uint32_t *data_words = (uint32_t *)data_block;
for (int i = 0; i < block_length(sha_type) / 4; i++) {
reg_addr_buf[i] = __bswap_32(data_words[i]);
}
asm volatile ("memw");
if(is_first_block) {
DPORT_REG_WRITE(SHA_START_REG(sha_type), 1);
} else {
DPORT_REG_WRITE(SHA_CONTINUE_REG(sha_type), 1);
}
esp_sha_unlock_memory_block();
/* Note: deliberately not waiting for this operation to complete,
as a performance tweak - delay waiting until the next time we need the SHA
unit, instead.
*/
}
void esp_sha(esp_sha_type sha_type, const unsigned char *input, size_t ilen, unsigned char *output)
{
size_t block_len = block_length(sha_type);
esp_sha_lock_engine(sha_type);
SHA_CTX ctx;
ets_sha_init(&ctx);
esp_sha_lock_memory_block();
while(ilen > 0) {
size_t chunk_len = (ilen > block_len) ? block_len : ilen;
esp_sha_wait_idle();
DPORT_STALL_OTHER_CPU_START();
{
// This SHA ROM function reads DPORT regs
ets_sha_update(&ctx, sha_type, input, chunk_len * 8);
}
DPORT_STALL_OTHER_CPU_END();
input += chunk_len;
ilen -= chunk_len;
}
esp_sha_wait_idle();
DPORT_STALL_OTHER_CPU_START();
{
ets_sha_finish(&ctx, sha_type, output);
}
DPORT_STALL_OTHER_CPU_END();
esp_sha_unlock_memory_block();
esp_sha_unlock_engine(sha_type);
}