Linux 内核irq_stack遍历

环境Centos 4.18.0-80.el8.x86_64

一、x86架构堆栈类型说明

https://www.kernel.org/doc/Documentation/x86/kernel-stacks

int get_stack_info(unsigned long *stack, struct task_struct *task,struct stack_info *info, unsigned long *visit_mask)
{if (!stack)goto unknown;task = task ? : current;if (in_task_stack(stack, task, info))goto recursion_check;if (task != current)goto unknown;if (in_exception_stack(stack, info))goto recursion_check;if (in_irq_stack(stack, info))goto recursion_check;if (in_entry_stack(stack, info))goto recursion_check;goto unknown;
}

从上述函数可以看出堆栈类型存在4种，在函数show_trace_log_lvl中有一段说明如下：

	/** Iterate through the stacks, starting with the current stack pointer.* Each stack has a pointer to the next one.** x86-64 can have several stacks:* - task stack* - interrupt stack* - HW exception stacks (double fault, nmi, debug, mce)* - entry stack** x86-32 can have up to four stacks:* - task stack* - softirq stack* - hardirq stack* - entry stack*/

x86架构中一般用寄存器sp来存在栈指针。

类型	说明
task_stack	进程栈 stack_trace_save可导出进程栈
exception_stack	异常栈
irq_stack	中断栈，大小为IRQ_STACK_SIZE 16KB
entry_stack	入口栈

二、Linux 内核函数 dump_stack

在之前的文章也介绍过这个函数的作用，可以打印函数调用栈。

lib/dump_stack.c

/*** dump_stack - dump the current task information and its stack trace** Architectures can override this implementation by implementing its own.*/
#ifdef CONFIG_SMP
static atomic_t dump_lock = ATOMIC_INIT(-1);asmlinkage __visible void dump_stack(void)
{unsigned long flags;int was_locked;int old;int cpu;/** Permit this cpu to perform nested stack dumps while serialising* against other CPUs*/
retry:local_irq_save(flags);cpu = smp_processor_id();old = atomic_cmpxchg(&dump_lock, -1, cpu);if (old == -1) {was_locked = 0;} else if (old == cpu) {was_locked = 1;} else {local_irq_restore(flags);cpu_relax();goto retry;}__dump_stack();if (!was_locked)atomic_set(&dump_lock, -1);local_irq_restore(flags);
}

|- dump_stack();	// lib/dump_stack.c|- __dump_stack();	// arch/x86/kernel/dumpstack.c|-