Linux 内核自己的栈在什么位置？

Roemer

从 elf 格式的vmlinux 或 vmlinux.lds.s 能读出来么？

kgn28

只是知道0号进程有个init_thread_union作为他的内核栈，其他无论什么进程还是内核线程都是使用动态创建的栈吧，就算是在启动过程中也只需要一个临时的栈就可以。有需要规定栈在确切的位置吗？

nettom

内核栈应该是固定的吧，2页大小。

32位  8k。  
64位  16k。

网上也有人说  内核栈和中断栈分开了， 内核只有1页。
不是很清楚，希望有高手解惑。

zyr-linux

没有所谓的内核自己的栈，只有各个进程在内核态下的栈
各种arch下不可一概而论，下面是最常见的x8664，按CPU分。

unsigned long kernelstack;  /* top of kernel stack for current */
char *irqstackptr;        /* top of irqstack */

1. /* Per processor datastructure. %gs points to it while the kernel runs */
   
2. struct x8664_pda {
   
3.         struct task_struct *pcurrent;        /* Current process */
   
4.         unsigned long data_offset;        /* Per cpu data offset from linker address */
   
5.         unsigned long kernelstack;  /* top of kernel stack for current */
   
6.         unsigned long oldrsp;             /* user rsp for system call */
   
7. #if DEBUG_STKSZ > EXCEPTION_STKSZ
   
8.         unsigned long debugstack;   /* #DB/#BP stack. */
   
9. #endif
   
10.         int irqcount;                    /* Irq nesting counter. Starts with -1 */         
    
11.         int cpunumber;                    /* Logical CPU number */
    
12.         char *irqstackptr;        /* top of irqstack */
    
13.         int nodenumber;                    /* number of current node */
    
14.         unsigned int __softirq_pending;
    
15.         unsigned int __nmi_count;        /* number of NMI on this CPUs */
    
16.         struct mm_struct *active_mm;
    
17.         int mmu_state;     
    
18.         unsigned apic_timer_irqs;
    
19. } ____cacheline_aligned_in_smp;

复制代码

kgn28

回复 3# nettom

4.6.1.4. Multiple Kernel Mode stacks
As mentioned in the section "Identifying a Process" in Chapter 3, the thread_info descriptor of each process is coupled with a Kernel Mode stack in a thread_union data structure composed by one or two page frames, according to an option selected when the kernel has been compiled. If the size of the tHRead_union structure is 8 KB, the Kernel Mode stack of the current process is used for every type of kernel control path: exceptions, interrupts, and deferrable functions (see the later section "Softirqs and Tasklets"). Conversely, if the size of the thread_union structure is 4 KB, the kernel makes use of three types of Kernel Mode stacks:

The exception stack is used when handling exceptions (including system calls). This is the stack contained in the per-process thread_union data structure, thus the kernel makes use of a different exception stack for each process in the system.

The hard IRQ stack is used when handling interrupts. There is one hard IRQ stack for each CPU in the system, and each stack is contained in a single page frame.

The soft IRQ stack is used when handling deferrable functions (softirqs or tasklets; see the later section "Softirqs and Tasklets"). There is one soft IRQ stack for each CPU in the system, and each stack is contained in a single page frame.

All hard IRQ stacks are contained in the hardirq_stack array, while all soft IRQ stacks are contained in the softirq_stack array. Each array element is a union of type irq_ctx that span a single page. At the bottom of this page is stored a thread_info structure, while the spare memory locations are used for the stack; remember that each stack grows towards lower addresses. Thus, hard IRQ stacks and soft IRQ stacks are very similar to the exception stacks described in the section "Identifying a Process" in Chapter 3; the only difference is that the tHRead_info structure coupled with each stack is associated with a CPU rather than a process.

The hardirq_ctx and softirq_ctx arrays allow the kernel to quickly determine the hard IRQ stack and soft IRQ stack of a given CPU, respectively: they contain pointers to the corresponding irq_ctx elements.

貌似，如果是4K，那么内核栈就是分类了的（异常没进城一个，中断（软硬）每cpu一个），如果是8K，那么都在8K中了。