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esp32 hwcrypto: Use spinlock instead of lock to protect AES

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More than doubles performance of mbedTLS AES self-tests.
This commit is contained in:
Angus Gratton 2017-08-16 09:06:52 +10:00 committed by Angus Gratton
parent 2624e10055
commit 50e0a54630
1 changed files with 18 additions and 3 deletions
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21
components/esp32/hwcrypto/aes.c
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@ -32,12 +32,26 @@
#include "soc/hwcrypto_reg.h"
#include <sys/lock.h>
static _lock_t aes_lock;
#include <freertos/FreeRTOS.h>
#include "soc/cpu.h"
#include <stdio.h>
/* AES uses a spinlock mux not a lock as the underlying block operation
only takes 208 cycles (to write key & compute block), +600 cycles
for DPORT protection but +3400 cycles again if you use a full sized lock.
For CBC, CFB, etc. this may mean that interrupts are disabled for a longer
period of time for bigger lengths. However at the moment this has to happen
anyway due to DPORT protection...
*/
static portMUX_TYPE aes_spinlock = portMUX_INITIALIZER_UNLOCKED;
void esp_aes_acquire_hardware( void )
{
/* newlib locks lazy initialize on ESP-IDF */
_lock_acquire(&aes_lock);
portENTER_CRITICAL(&aes_spinlock);
DPORT_STALL_OTHER_CPU_START();
{
@ -65,7 +79,7 @@ void esp_aes_release_hardware( void )
}
DPORT_STALL_OTHER_CPU_END();
_lock_release(&aes_lock);
portEXIT_CRITICAL(&aes_spinlock);
}
void esp_aes_init( esp_aes_context *ctx )
@ -178,6 +192,7 @@ int esp_aes_crypt_ecb( esp_aes_context *ctx,
esp_aes_setkey_hardware(ctx, mode);
esp_aes_block(input, output);
esp_aes_release_hardware();
return 0;
}