Posted on 2012-10-15 10:37
鑫龙 阅读(595)
评论(0) 编辑 收藏 引用 所属分类:
linux内核
Linux通过slab分配器动态分配task_struct结构，该结构定义在了<include/linux/sched.h>文件中，进程描述符中包含一个具体进程的所有信息，各个进程的task_struct存放在它们内核栈的尾端。在栈底（对于向下增长的栈）或栈顶（对于向上增长的栈）创建一个新的结构struct thread_info。利用这个新的机构来迅速的找到task_struct的位置。 下面是kernel2.6.32.10里task_struct的定义（对于x86类型的CPU来说文件位于：arch/x86/include/asm /include/asm/thread_info.h）：- struct thread_info {
- struct task_struct *task; /* main task structure */
- struct exec_domain *exec_domain; /* execution domain */
- __u32 flags; /* low level flags */
- __u32 status; /* thread synchronous flags */
- __u32 cpu; /* current CPU */
- int preempt_count; /* 0 => preemptable, <0 => BUG */
- mm_segment_t addr_limit;
- struct restart_block restart_block;
- void __user *sysenter_return;
- #ifdef CONFIG_X86_32
- unsigned long previous_esp; /* ESP of the previous stack in case of nested (IRQ) stacks*/
- __u8 supervisor_stack[0];
- #endif
- int uaccess_err;
- };
- /* how to get the current stack pointer from C */
- register unsigned long current_stack_pointer asm("esp") __used;
- /* how to get the thread information struct from C */
- static inline struct thread_info *current_thread_info(void)
- {
- return (struct thread_info *)
- (current_stack_pointer & ~(THREAD_SIZE - 1));
- };