Tasmota/tasmota/StackThunk_light.cpp

148 lines
4.5 KiB
C++

/*
StackThunk_light.c - Allow use second stack for BearSSL calls
Light version with reduced Stack size due to Tasmota optimizations.
BearSSL uses a significant amount of stack space, much larger than
the default Arduino core stack. These routines handle swapping
between a secondary, user-allocated stack on the heap and the real
stack.
Copyright (C) 2021 Earle F. Philhower, III. All rights reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Modified 8 May 2015 by Hristo Gochkov (proper post and file upload handling)
*/
#include "my_user_config.h"
#include "tasmota_configurations.h"
#include <stdint.h>
#include <stdlib.h>
#include "StackThunk_light.h"
#include <ets_sys.h>
extern "C" {
uint32_t *stack_thunk_light_ptr = NULL;
uint32_t *stack_thunk_light_top = NULL;
uint32_t *stack_thunk_light_save = NULL; /* Saved A1 while in BearSSL */
uint32_t stack_thunk_light_refcnt = 0;
//#define _stackSize (5600/4)
#if defined(USE_MQTT_AWS_IOT)
#define _stackSize (5300/4) // using a light version of bearssl we can save 300 bytes
#elif defined(USE_MQTT_TLS_FORCE_EC_CIPHER) || defined(USE_4K_RSA)
#define _stackSize (4800/4) // no private key, we can reduce a little, max observed 4300
#else
#define _stackSize (3600/4) // using a light version of bearssl we can save 2k
#endif
#define _stackPaint 0xdeadbeef
/* Add a reference, and allocate the stack if necessary */
void stack_thunk_light_add_ref()
{
stack_thunk_light_refcnt++;
if (stack_thunk_light_refcnt == 1) {
stack_thunk_light_ptr = (uint32_t *)malloc(_stackSize * sizeof(uint32_t));
stack_thunk_light_top = stack_thunk_light_ptr + _stackSize - 1;
stack_thunk_light_save = NULL;
stack_thunk_light_repaint();
}
}
/* Drop a reference, and free stack if no more in use */
void stack_thunk_light_del_ref()
{
if (stack_thunk_light_refcnt == 0) {
/* Error! */
return;
}
stack_thunk_light_refcnt--;
if (!stack_thunk_light_refcnt) {
free(stack_thunk_light_ptr);
stack_thunk_light_ptr = NULL;
stack_thunk_light_top = NULL;
stack_thunk_light_save = NULL;
}
}
void stack_thunk_light_repaint()
{
if (stack_thunk_light_ptr) {
for (int i=0; i < _stackSize; i++) {
stack_thunk_light_ptr[i] = _stackPaint;
}
}
}
/* Simple accessor functions used by postmortem */
uint32_t stack_thunk_light_get_refcnt() {
return stack_thunk_light_refcnt;
}
uint32_t stack_thunk_light_get_stack_top() {
return (uint32_t)stack_thunk_light_top;
}
uint32_t stack_thunk_light_get_stack_bot() {
return (uint32_t)stack_thunk_light_ptr;
}
uint32_t stack_thunk_light_get_cont_sp() {
return (uint32_t)stack_thunk_light_save;
}
/* Return the number of bytes ever used since the stack was created */
uint32_t stack_thunk_light_get_max_usage()
{
uint32_t cnt = 0;
/* No stack == no usage by definition! */
if (!stack_thunk_light_ptr) {
return 0;
}
for (cnt=0; (cnt < _stackSize) && (stack_thunk_light_ptr[cnt] == _stackPaint); cnt++) {
/* Noop, all work done in for() */
}
return 4 * (_stackSize - cnt);
}
/* Print the stack from the first used 16-byte chunk to the top, decodable by the exception decoder */
// void stack_thunk_light_dump_stack()
// {
// uint32_t *pos = stack_thunk_light_top;
// while (pos < stack_thunk_light_ptr) {
// if ((pos[0] != _stackPaint) || (pos[1] != _stackPaint) || (pos[2] != _stackPaint) || (pos[3] != _stackPaint))
// break;
// pos += 4;
// }
// ets_printf(">>>stack>>>\n");
// while (pos < stack_thunk_light_ptr) {
// ets_printf("%08x: %08x %08x %08x %08x\n", (int32_t)pos, pos[0], pos[1], pos[2], pos[3]);
// pos += 4;
// }
// ets_printf("<<<stack<<<\n");
// }
/* Called when the stack overflow is detected by a thunk. Main memory is corrupted at this point. Do not return. */
void stack_thunk_light_fatal_overflow()
{
// ets_printf("FATAL ERROR: BSSL stack overflow\n");
abort();
}
};