void notrace walk_stackframe()

in kernel/stacktrace.c [16:57]

• 35 lines of code
• 9 McCabe index (conditional complexity)

void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
			     bool (*fn)(unsigned long, void *), void *arg)
{
	unsigned long fp, sp, pc;

	if (regs) {
		fp = frame_pointer(regs);
		sp = user_stack_pointer(regs);
		pc = instruction_pointer(regs);
	} else if (task == NULL || task == current) {
		const register unsigned long current_sp __asm__ ("sp");
		const register unsigned long current_fp __asm__ ("r8");
		fp = current_fp;
		sp = current_sp;
		pc = (unsigned long)walk_stackframe;
	} else {
		/* task blocked in __switch_to */
		fp = thread_saved_fp(task);
		sp = thread_saved_sp(task);
		pc = thread_saved_lr(task);
	}

	for (;;) {
		unsigned long low, high;
		struct stackframe *frame;

		if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
			break;

		/* Validate frame pointer */
		low = sp;
		high = ALIGN(sp, THREAD_SIZE);
		if (unlikely(fp < low || fp > high || fp & 0x3))
			break;
		/* Unwind stack frame */
		frame = (struct stackframe *)fp;
		sp = fp;
		fp = frame->fp;
		pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
					   (unsigned long *)(fp - 8));
	}
}