Function unwind_stack_one

freebsd/arm/arm/unwind.c:547–575

* Unwind a single stack frame. * Return 0 on success or 1 if the stack cannot be unwound any further. * * XXX The can_lock argument is no longer germane; a sweep of callers should be * made to remove it after this new code has proven itself for a while. */

 * made to remove it after this new code has proven itself for a while.
 */
int
unwind_stack_one(struct unwind_state *state, int can_lock __unused)
{
	struct unwind_idx *index;

	/* Reset the mask of updated registers */
	state->update_mask = 0;

	/* The pc value is correct and will be overwritten, save it */
	state->start_pc = state->registers[PC];

	/* Find the item to run */
	index = find_index(state->start_pc);
	if (index == NULL || index->insn == EXIDX_CANTUNWIND)
		return 1;

	if (index->insn & (1U << 31)) {
		/* The data is within the instruction */
		state->insn = &index->insn;
	} else {
		/* A prel31 offset to the unwind table */
		state->insn = (uint32_t *)
		    ((uintptr_t)&index->insn +
		     expand_prel31(index->insn));
	}

	/* Run the unwind function, return its finished/not-finished status. */
	return (unwind_tab(state));
}