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TOMOYO Linux Cross Reference
Linux/include/linux/sched/task_stack.h

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 #ifndef _LINUX_SCHED_TASK_STACK_H
  3 #define _LINUX_SCHED_TASK_STACK_H
  4 
  5 /*
  6  * task->stack (kernel stack) handling interfaces:
  7  */
  8 
  9 #include <linux/sched.h>
 10 #include <linux/magic.h>
 11 
 12 #ifdef CONFIG_THREAD_INFO_IN_TASK
 13 
 14 /*
 15  * When accessing the stack of a non-current task that might exit, use
 16  * try_get_task_stack() instead.  task_stack_page will return a pointer
 17  * that could get freed out from under you.
 18  */
 19 static inline void *task_stack_page(const struct task_struct *task)
 20 {
 21         return task->stack;
 22 }
 23 
 24 #define setup_thread_stack(new,old)     do { } while(0)
 25 
 26 static inline unsigned long *end_of_stack(const struct task_struct *task)
 27 {
 28         return task->stack;
 29 }
 30 
 31 #elif !defined(__HAVE_THREAD_FUNCTIONS)
 32 
 33 #define task_stack_page(task)   ((void *)(task)->stack)
 34 
 35 static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
 36 {
 37         *task_thread_info(p) = *task_thread_info(org);
 38         task_thread_info(p)->task = p;
 39 }
 40 
 41 /*
 42  * Return the address of the last usable long on the stack.
 43  *
 44  * When the stack grows down, this is just above the thread
 45  * info struct. Going any lower will corrupt the threadinfo.
 46  *
 47  * When the stack grows up, this is the highest address.
 48  * Beyond that position, we corrupt data on the next page.
 49  */
 50 static inline unsigned long *end_of_stack(struct task_struct *p)
 51 {
 52 #ifdef CONFIG_STACK_GROWSUP
 53         return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
 54 #else
 55         return (unsigned long *)(task_thread_info(p) + 1);
 56 #endif
 57 }
 58 
 59 #endif
 60 
 61 #ifdef CONFIG_THREAD_INFO_IN_TASK
 62 static inline void *try_get_task_stack(struct task_struct *tsk)
 63 {
 64         return atomic_inc_not_zero(&tsk->stack_refcount) ?
 65                 task_stack_page(tsk) : NULL;
 66 }
 67 
 68 extern void put_task_stack(struct task_struct *tsk);
 69 #else
 70 static inline void *try_get_task_stack(struct task_struct *tsk)
 71 {
 72         return task_stack_page(tsk);
 73 }
 74 
 75 static inline void put_task_stack(struct task_struct *tsk) {}
 76 #endif
 77 
 78 #define task_stack_end_corrupted(task) \
 79                 (*(end_of_stack(task)) != STACK_END_MAGIC)
 80 
 81 static inline int object_is_on_stack(const void *obj)
 82 {
 83         void *stack = task_stack_page(current);
 84 
 85         return (obj >= stack) && (obj < (stack + THREAD_SIZE));
 86 }
 87 
 88 extern void thread_stack_cache_init(void);
 89 
 90 #ifdef CONFIG_DEBUG_STACK_USAGE
 91 static inline unsigned long stack_not_used(struct task_struct *p)
 92 {
 93         unsigned long *n = end_of_stack(p);
 94 
 95         do {    /* Skip over canary */
 96 # ifdef CONFIG_STACK_GROWSUP
 97                 n--;
 98 # else
 99                 n++;
100 # endif
101         } while (!*n);
102 
103 # ifdef CONFIG_STACK_GROWSUP
104         return (unsigned long)end_of_stack(p) - (unsigned long)n;
105 # else
106         return (unsigned long)n - (unsigned long)end_of_stack(p);
107 # endif
108 }
109 #endif
110 extern void set_task_stack_end_magic(struct task_struct *tsk);
111 
112 #ifndef __HAVE_ARCH_KSTACK_END
113 static inline int kstack_end(void *addr)
114 {
115         /* Reliable end of stack detection:
116          * Some APM bios versions misalign the stack
117          */
118         return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
119 }
120 #endif
121 
122 #endif /* _LINUX_SCHED_TASK_STACK_H */
123 

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