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Allow max stack checking to be used with -flto build by determining top

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of stack in a different way.
This commit is contained in:
Dan Halbert 2017-08-05 17:43:48 -04:00 committed by Scott Shawcroft
parent 91d4cdb476
commit 5d509ecace
2 changed files with 18 additions and 4 deletions
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1
atmel-samd/Makefile
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@ -132,6 +132,7 @@ CFLAGS = $(INC) -Wall -Werror -std=gnu11 -nostdlib $(CFLAGS_CORTEX_M0) $(CFLAGS_
ifeq ($(DEBUG), 1) ifeq ($(DEBUG), 1)
# NDEBUG disables assert() statements. This reduces code size pretty dramatically, per tannewt. # NDEBUG disables assert() statements. This reduces code size pretty dramatically, per tannewt.
# Turn on Python modules useful for debugging (e.g. uheap, ustack). # Turn on Python modules useful for debugging (e.g. uheap, ustack).
# -DMICROPY_DEBUG_MODULES may also be added to an -flto build, if you wish.
CFLAGS += -Os -ggdb -DNDEBUG -DENABLE_MICRO_TRACE_BUFFER -DMICROPY_DEBUG_MODULES CFLAGS += -Os -ggdb -DNDEBUG -DENABLE_MICRO_TRACE_BUFFER -DMICROPY_DEBUG_MODULES
else else
CFLAGS += -Os -DNDEBUG -flto CFLAGS += -Os -DNDEBUG -flto

21
py/stackctrl.c
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@ -77,14 +77,27 @@ void mp_stack_set_bottom(void* stack_bottom) {
MP_STATE_THREAD(stack_bottom) = 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. // Fill stack space down toward the stack limit with a known unusual value.
void mp_stack_fill_with_sentinel(void) { void mp_stack_fill_with_sentinel(void) {
// Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto. // Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
__asm volatile (""); __asm volatile ("");
volatile char* volatile p; // Start filling stack just below the current stack frame.
// Start filling stack just below the last variable in the current stack frame, which is p. // Continue until we've hit the bottom of the stack (lowest address,
// Continue until we've hit the bottom of the stack (lowest address, logical "ceiling" of stack). // logical "ceiling" of stack).
p = (char *) (&p - 1); char* p = (char *) approx_stack_pointer() - 1;
while(p >= MP_STATE_THREAD(stack_bottom)) { while(p >= MP_STATE_THREAD(stack_bottom)) {
*p-- = MP_MAX_STACK_USAGE_SENTINEL_BYTE; *p-- = MP_MAX_STACK_USAGE_SENTINEL_BYTE;
} }