LXR linux/include/linux/sched/task

   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 */
  18static 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
  25static 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
  34static 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 */
  49static 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
  61static 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
  67extern void put_task_stack(struct task_struct *tsk);
  68#else
  69static inline void *try_get_task_stack(struct task_struct *tsk)
  70{
  71        return task_stack_page(tsk);
  72}
  73
  74static 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
  80static 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
  87extern void thread_stack_cache_init(void);
  88
  89#ifdef CONFIG_DEBUG_STACK_USAGE
  90static 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
 109extern void set_task_stack_end_magic(struct task_struct *tsk);
 110
 111#ifndef __HAVE_ARCH_KSTACK_END
 112static 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