circuitpython/py/stackctrl.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2014 Paul Sokolovsky
*
* 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 "py/runtime.h"
#include "py/stackctrl.h"
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void mp_stack_ctrl_init(void) {
// Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
__asm volatile ("");
volatile int stack_dummy;
MP_STATE_THREAD(stack_top) = (char*)&stack_dummy;
}
void mp_stack_set_top(void *top) {
MP_STATE_THREAD(stack_top) = top;
}
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mp_uint_t mp_stack_usage(void) {
// Assumes descending stack
// Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
__asm volatile ("");
volatile int stack_dummy;
return MP_STATE_THREAD(stack_top) - (char*)&stack_dummy;
}
#if MICROPY_STACK_CHECK
void mp_stack_set_limit(mp_uint_t limit) {
MP_STATE_THREAD(stack_limit) = limit;
}
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void mp_stack_check(void) {
if (mp_stack_usage() >= MP_STATE_THREAD(stack_limit)) {
mp_raise_recursion_depth();
}
}
#endif // MICROPY_STACK_CHECK
#if MICROPY_MAX_STACK_USAGE
// Fill stack space with this unusual value.
const char MP_MAX_STACK_USAGE_SENTINEL_BYTE = 0xEE;
// Record absolute bottom (logical limit) of stack.
void mp_stack_set_bottom(void* stack_bottom) {
MP_STATE_THREAD(stack_bottom) = stack_bottom;
}
// Return the current frame pointer. This can be used as an
// approximation for the stack pointer of the _calling_ function.
// This routine must not be inlined. This method is
// architecture-independent, as opposed to using asm("sp") or similar.
//
// The stack_dummy approach used elsewhere in this file is not safe in
// all cases. That value may be below the actual top of the stack.
static void* approx_stack_pointer(void){
__asm volatile ("");
return __builtin_frame_address(0);
}
// Fill stack space down toward the stack limit with a known unusual value.
void mp_stack_fill_with_sentinel(void) {
// Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
__asm volatile ("");
// Start filling stack just below the current stack frame.
// Continue until we've hit the bottom of the stack (lowest address,
// logical "ceiling" of stack).
char* p = (char *) approx_stack_pointer() - 1;
while(p >= MP_STATE_THREAD(stack_bottom)) {
*p-- = MP_MAX_STACK_USAGE_SENTINEL_BYTE;
}
}
#endif // MICROPY_MAX_STACK_USAGE