static int unwind_special()

in kernel/unwind.c [214:272]

• 46 lines of code
• 8 McCabe index (conditional complexity)

static int unwind_special(struct unwind_frame_info *info, unsigned long pc, int frame_size)
{
	/*
	 * We have to use void * instead of a function pointer, because
	 * function pointers aren't a pointer to the function on 64-bit.
	 * Make them const so the compiler knows they live in .text
	 * Note: We could use dereference_kernel_function_descriptor()
	 * instead but we want to keep it simple here.
	 */
	extern void * const handle_interruption;
	extern void * const ret_from_kernel_thread;
	extern void * const syscall_exit;
	extern void * const intr_return;
	extern void * const _switch_to_ret;
#ifdef CONFIG_IRQSTACKS
	extern void * const _call_on_stack;
#endif /* CONFIG_IRQSTACKS */

	if (pc_is_kernel_fn(pc, handle_interruption)) {
		struct pt_regs *regs = (struct pt_regs *)(info->sp - frame_size - PT_SZ_ALGN);
		dbg("Unwinding through handle_interruption()\n");
		info->prev_sp = regs->gr[30];
		info->prev_ip = regs->iaoq[0];
		return 1;
	}

	if (pc_is_kernel_fn(pc, ret_from_kernel_thread) ||
	    pc_is_kernel_fn(pc, syscall_exit)) {
		info->prev_sp = info->prev_ip = 0;
		return 1;
	}

	if (pc_is_kernel_fn(pc, intr_return)) {
		struct pt_regs *regs;

		dbg("Found intr_return()\n");
		regs = (struct pt_regs *)(info->sp - PT_SZ_ALGN);
		info->prev_sp = regs->gr[30];
		info->prev_ip = regs->iaoq[0];
		info->rp = regs->gr[2];
		return 1;
	}

	if (pc_is_kernel_fn(pc, _switch_to) ||
	    pc_is_kernel_fn(pc, _switch_to_ret)) {
		info->prev_sp = info->sp - CALLEE_SAVE_FRAME_SIZE;
		info->prev_ip = *(unsigned long *)(info->prev_sp - RP_OFFSET);
		return 1;
	}

#ifdef CONFIG_IRQSTACKS
	if (pc_is_kernel_fn(pc, _call_on_stack)) {
		info->prev_sp = *(unsigned long *)(info->sp - FRAME_SIZE - REG_SZ);
		info->prev_ip = *(unsigned long *)(info->sp - FRAME_SIZE - RP_OFFSET);
		return 1;
	}
#endif
	return 0;
}