Line data    Source code

       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     8648183 : static inline void *task_stack_page(const struct task_struct *task)
      20             : {
      21     7519927 :         return task->stack;
      22             : }
      23             : 
      24             : #define setup_thread_stack(new,old)     do { } while(0)
      25             : 
      26         917 : static inline unsigned long *end_of_stack(const struct task_struct *task)
      27             : {
      28         916 :         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          54 : static inline void *try_get_task_stack(struct task_struct *tsk)
      63             : {
      64          54 :         return refcount_inc_not_zero(&tsk->stack_refcount) ?
      65          54 :                 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     1128202 : static inline int object_is_on_stack(const void *obj)
      82             : {
      83     1128202 :         void *stack = task_stack_page(current);
      84             : 
      85     1128202 :         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 */