1 #ifndef _LINUX_SCHED_TASK_STACK_H 2 #define _LINUX_SCHED_TASK_STACK_H 3 4 /* 5 * task->stack (kernel stack) handling interfaces: 6 */ 7 8 #include <linux/sched.h> 9 #include <linux/magic.h> 10 11 #ifdef CONFIG_THREAD_INFO_IN_TASK 12 13 /* 14 * When accessing the stack of a non-current task that might exit, use 15 * try_get_task_stack() instead. task_stack_page will return a pointer 16 * that could get freed out from under you. 17 */ 18 static inline void *task_stack_page(const struct task_struct *task) 19 { 20 return task->stack; 21 } 22 23 #define setup_thread_stack(new,old) do { } while(0) 24 25 static inline unsigned long *end_of_stack(const struct task_struct *task) 26 { 27 return task->stack; 28 } 29 30 #elif !defined(__HAVE_THREAD_FUNCTIONS) 31 32 #define task_stack_page(task) ((void *)(task)->stack) 33 34 static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org) 35 { 36 *task_thread_info(p) = *task_thread_info(org); 37 task_thread_info(p)->task = p; 38 } 39 40 /* 41 * Return the address of the last usable long on the stack. 42 * 43 * When the stack grows down, this is just above the thread 44 * info struct. Going any lower will corrupt the threadinfo. 45 * 46 * When the stack grows up, this is the highest address. 47 * Beyond that position, we corrupt data on the next page. 48 */ 49 static inline unsigned long *end_of_stack(struct task_struct *p) 50 { 51 #ifdef CONFIG_STACK_GROWSUP 52 return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1; 53 #else 54 return (unsigned long *)(task_thread_info(p) + 1); 55 #endif 56 } 57 58 #endif 59 60 #ifdef CONFIG_THREAD_INFO_IN_TASK 61 static inline void *try_get_task_stack(struct task_struct *tsk) 62 { 63 return atomic_inc_not_zero(&tsk->stack_refcount) ? 64 task_stack_page(tsk) : NULL; 65 } 66 67 extern void put_task_stack(struct task_struct *tsk); 68 #else 69 static inline void *try_get_task_stack(struct task_struct *tsk) 70 { 71 return task_stack_page(tsk); 72 } 73 74 static inline void put_task_stack(struct task_struct *tsk) {} 75 #endif 76 77 #define task_stack_end_corrupted(task) \ 78 (*(end_of_stack(task)) != STACK_END_MAGIC) 79 80 static inline int object_is_on_stack(void *obj) 81 { 82 void *stack = task_stack_page(current); 83 84 return (obj >= stack) && (obj < (stack + THREAD_SIZE)); 85 } 86 87 extern void thread_stack_cache_init(void); 88 89 #ifdef CONFIG_DEBUG_STACK_USAGE 90 static inline unsigned long stack_not_used(struct task_struct *p) 91 { 92 unsigned long *n = end_of_stack(p); 93 94 do { /* Skip over canary */ 95 # ifdef CONFIG_STACK_GROWSUP 96 n--; 97 # else 98 n++; 99 # endif 100 } while (!*n); 101 102 # ifdef CONFIG_STACK_GROWSUP 103 return (unsigned long)end_of_stack(p) - (unsigned long)n; 104 # else 105 return (unsigned long)n - (unsigned long)end_of_stack(p); 106 # endif 107 } 108 #endif 109 extern void set_task_stack_end_magic(struct task_struct *tsk); 110 111 #ifndef __HAVE_ARCH_KSTACK_END 112 static inline int kstack_end(void *addr) 113 { 114 /* Reliable end of stack detection: 115 * Some APM bios versions misalign the stack 116 */ 117 return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*))); 118 } 119 #endif 120 121 #endif /* _LINUX_SCHED_TASK_STACK_H */ 122