static int lookup_prev_stack_frame()

in kernel/unwind.c [125:152]

• 20 lines of code
• 6 McCabe index (conditional complexity)

static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
				   unsigned long leaf_return,
				   unsigned long *pprev_fp,
				   unsigned long *pprev_pc)
{
	unsigned long *prologue = NULL;

	/* _switch_to is a special leaf function */
	if (pc != (unsigned long) &_switch_to)
		prologue = find_frame_creation((unsigned long *)pc);

	if (prologue) {
		long frame_size = get_frame_size(*prologue);

		*pprev_fp = fp + frame_size;
		*pprev_pc = *(unsigned long *)fp;
	} else {
		if (!leaf_return)
			return -EINVAL;
		*pprev_pc = leaf_return;
		*pprev_fp = fp;
	}

	/* NOTE: don't check kernel_text_address here, to allow display
	 *	 of userland return address
	 */
	return (!*pprev_pc || (*pprev_pc & 3)) ? -EINVAL : 0;
}