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mbedtls hardware bignum: Support "RSA" interrupt for end of operation

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Allows CPU to do other things which bignum operation is in
progress.
This commit is contained in:
Angus Gratton 2016-11-18 15:53:00 +11:00
parent 68d370542a
commit 36f29017b6
2 changed files with 60 additions and 4 deletions
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16
components/mbedtls/Kconfig
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@ -51,6 +51,22 @@ config MBEDTLS_HARDWARE_MPI
These operations are used by RSA.
config MBEDTLS_MPI_USE_INTERRUPT
bool "Use interrupt for MPI operations"
depends on MBEDTLS_HARDWARE_MPI
default y
help
Use an interrupt to coordinate MPI operations.
This allows other code to run on the CPU while an MPI operation is pending.
Otherwise the CPU busy-waits.
config MBEDTLS_MPI_INTERRUPT_NUM
int "MPI Interrupt number"
depends on MBEDTLS_MPI_USE_INTERRUPT
default 18
help
CPU interrupt number for MPI interrupt to connect to. Must be otherwise unused.
Eventually this assignment will be handled automatically at runtime.
endmenu

48
components/mbedtls/port/esp_bignum.c
View file

@ -31,12 +31,43 @@
#include "soc/hwcrypto_reg.h"
#include "esp_system.h"
#include "esp_log.h"
#include "esp_intr.h"
#include "esp_attr.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#if defined(MBEDTLS_MPI_MUL_MPI_ALT) || defined(MBEDTLS_MPI_EXP_MOD_ALT)
static const char *TAG = "bignum";
#if defined(CONFIG_MBEDTLS_MPI_USE_INTERRUPT)
static SemaphoreHandle_t op_complete_sem;
static IRAM_ATTR void rsa_complete_isr(void *arg)
{
BaseType_t higher_woken;
REG_WRITE(RSA_INTERRUPT_REG, 1);
xSemaphoreGiveFromISR(op_complete_sem, &higher_woken);
if (higher_woken) {
portYIELD_FROM_ISR();
}
}
static void rsa_isr_initialise()
{
if (op_complete_sem == NULL) {
op_complete_sem = xSemaphoreCreateBinary();
intr_matrix_set(xPortGetCoreID(), ETS_RSA_INTR_SOURCE, CONFIG_MBEDTLS_MPI_INTERRUPT_NUM);
xt_set_interrupt_handler(CONFIG_MBEDTLS_MPI_INTERRUPT_NUM, &rsa_complete_isr, NULL);
xthal_set_intclear(1 << CONFIG_MBEDTLS_MPI_INTERRUPT_NUM);
xt_ints_on(1 << CONFIG_MBEDTLS_MPI_INTERRUPT_NUM);
}
}
#endif /* CONFIG_MBEDTLS_MPI_USE_INTERRUPT */
static _lock_t mpi_lock;
/* At the moment these hardware locking functions aren't exposed publically
@ -47,6 +78,9 @@ static void esp_mpi_acquire_hardware( void )
/* newlib locks lazy initialize on ESP-IDF */
_lock_acquire(&mpi_lock);
ets_bigint_enable();
#ifdef CONFIG_MBEDTLS_MPI_USE_INTERRUPT
rsa_isr_initialise();
#endif
}
static void esp_mpi_release_hardware( void )
@ -187,13 +221,21 @@ static int calculate_rinv(mbedtls_mpi *Rinv, const mbedtls_mpi *M, int num_words
*/
static inline void execute_op(uint32_t op_reg)
{
/* Clear interrupt status, start operation */
/* Clear interrupt status */
REG_WRITE(RSA_INTERRUPT_REG, 1);
REG_WRITE(op_reg, 1);
/* TODO: use interrupt instead of busywaiting */
#ifdef CONFIG_MBEDTLS_MPI_USE_INTERRUPT
if (!xSemaphoreTake(op_complete_sem, 2000 / portTICK_PERIOD_MS)) {
ESP_LOGE(TAG, "Timed out waiting for RSA operation (op_reg 0x%x int_reg 0x%x)",
op_reg, REG_READ(RSA_INTERRUPT_REG));
abort(); /* indicates a fundamental problem with driver */
}
#else
while(REG_READ(RSA_INTERRUPT_REG) != 1)
{ }
#endif
/* clear the interrupt */
REG_WRITE(RSA_INTERRUPT_REG, 1);
@ -356,8 +398,6 @@ static int modular_multiply_finish(mbedtls_mpi *Z, const mbedtls_mpi *X, const m
#if defined(MBEDTLS_MPI_MUL_MPI_ALT) /* MBEDTLS_MPI_MUL_MPI_ALT */
static const char *TAG = "bignum";
static int mpi_mult_mpi_failover_mod_mult(mbedtls_mpi *Z, const mbedtls_mpi *X, const mbedtls_mpi *Y, size_t num_words);
/* Z = X * Y */