include/linux/sched/task_stack.h

   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 */