linux – 了解从进程内核堆栈获取task_struct指针

26 struct thread_info {
 27         struct task_struct      *task;          /* main task structure */
 28         struct exec_domain      *exec_domain;   /* execution domain */
 29         __u32                   flags;          /* low level flags */
 30         __u32                   status;         /* thread synchronous flags */
 31         __u32                   cpu;            /* current cpu */
 32         int                     preempt_count;  /* 0 => preemptable,33                                                    <0 => BUG */
 34         mm_segment_t            addr_limit;
 35         struct restarT_Block    restarT_Block;
 36         void __user             *sysenter_return;
 37 #ifdef CONfig_X86_32
 38         unsigned long           prevIoUs_esp;   /* ESP of the prevIoUs stack in
 39                                                    case of nested (IRQ) stacks
 40                                                 */
 41         __u8                    supervisor_stack[0];
 42 #endif
 43         unsigned int            sig_on_uaccess_error:1;
 44         unsigned int            uaccess_err:1;  /* uaccess Failed */
 45 };

因此,要获取task_struct,您需要从ASM代码获取带有GET_THREAD_INFO的thread_info指针：

183 /* how to get the thread information struct from ASM */
184 #define GET_THREAD_INFO(reg)     \
185         movl $-THREAD_SIZE,reg; \
186         andl %esp,reg

…或者使用C代码中的current_thread_info：

174 /* how to get the thread information struct from C */
175 static inline struct thread_info *current_thread_info(void)
176 {
177         return (struct thread_info *)
178                 (current_stack_pointer & ~(THREAD_SIZE - 1));
179 }

注意,对于x86_32和x86_64,定义为(PAGE_SIZE<<< THREAD_SIZE_ORDER)和THREAD_SIZE_ORDER的THREAD_SIZE等于1,因此THREAD_SIZE导致8192(2 ^ 13或1 <<<<<<< 13).