circuitpython/supervisor/shared/stack.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "stack.h"

#include "py/mpconfig.h"
#include "py/runtime.h"
#include "supervisor/cpu.h"

extern uint32_t _estack;

static uint32_t next_stack_size = CIRCUITPY_DEFAULT_STACK_SIZE;
static uint32_t current_stack_size = 0;
supervisor_allocation* stack_alloc = NULL;

#define EXCEPTION_STACK_SIZE 1024

#define STACK_CANARY_VALUE 0x017829ef

void allocate_stack(void) {
    mp_uint_t regs[10];
    mp_uint_t sp = cpu_get_regs_and_sp(regs);

    mp_uint_t c_size = (uint32_t) &_estack - sp;

    stack_alloc = allocate_memory(c_size + next_stack_size + EXCEPTION_STACK_SIZE, true);
    if (stack_alloc == NULL) {
        stack_alloc = allocate_memory(c_size + CIRCUITPY_DEFAULT_STACK_SIZE + EXCEPTION_STACK_SIZE, true);
        current_stack_size = CIRCUITPY_DEFAULT_STACK_SIZE;
    } else {
        current_stack_size = next_stack_size;
    }
    *stack_alloc->ptr = STACK_CANARY_VALUE;
}

inline bool stack_ok(void) {
    return *stack_alloc->ptr == STACK_CANARY_VALUE;
}

inline void assert_heap_ok(void) {
    if (!stack_ok()) {
        asm("nop");
        while(true) {}
        mp_raise_RuntimeError(translate("Stack clobbered heap."));
    }
}

void stack_init(void) {
    allocate_stack();
}

void stack_resize(void) {
    if (next_stack_size == current_stack_size) {
        *stack_alloc->ptr = STACK_CANARY_VALUE;
        return;
    }
    free_memory(stack_alloc);
    stack_alloc = NULL;
    allocate_stack();
}

void set_next_stack_size(uint32_t size) {
    next_stack_size = size;
}

uint32_t get_current_stack_size(void) {
    return current_stack_size;
}