ardupilot/libraries/memcheck/memcheck.cpp

71 lines
1.7 KiB
C++

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
* note that we use a 32 bit sentinel to reduce the chance
* of false positives with uninitialised stack variables
*/
#include <stdlib.h>
#include <stdint.h>
#include <AP_HAL_Boards.h>
static const uint32_t *stack_low;
extern unsigned __brkval;
#define STACK_OFFSET 2
#define SENTINEL 0x28021967
/*
* return the current stack pointer
*/
static __attribute__((noinline)) const uint32_t *current_stackptr(void)
{
return (const uint32_t *)__builtin_frame_address(0);
}
/*
* this can be added in deeply nested code to ensure we catch
* deep stack usage. It should be caught by the sentinel, but this
* is an added protection
*/
void memcheck_update_stackptr(void)
{
if (current_stackptr() < stack_low) {
uintptr_t s = (uintptr_t)(current_stackptr() - STACK_OFFSET);
stack_low = (uint32_t *)(s & ~3);
}
}
/*
* initialise memcheck, setting up the sentinels
*/
void memcheck_init(void)
{
#if CONFIG_HAL_BOARD != HAL_BOARD_AVR_SITL
uint32_t *p;
free(malloc(1)); // ensure heap is initialised
stack_low = current_stackptr();
memcheck_update_stackptr();
for (p=(uint32_t *)(stack_low-1); p>(uint32_t *)__brkval; p--) {
*p = SENTINEL;
}
#endif
}
/*
* this returns the real amount of free memory by looking for
* overwrites of the stack sentinel values
*/
unsigned memcheck_available_memory(void)
{
#if CONFIG_HAL_BOARD == HAL_BOARD_AVR_SITL
return 0x1000;
#else
memcheck_update_stackptr();
while (*stack_low != SENTINEL && stack_low > (const uint32_t *)__brkval) {
stack_low--;
}
return (uintptr_t)(stack_low) - __brkval;
#endif
}