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             : static __always_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 __always_inline unsigned long *end_of_stack(const struct task_struct *task)
      27             : {
      28             : #ifdef CONFIG_STACK_GROWSUP
      29             :         return (unsigned long *)((unsigned long)task->stack + THREAD_SIZE) - 1;
      30             : #else
      31             :         return task->stack;
      32             : #endif
      33             : }
      34             : 
      35             : #elif !defined(__HAVE_THREAD_FUNCTIONS)
      36             : 
      37             : #define task_stack_page(task)   ((void *)(task)->stack)
      38             : 
      39             : static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
      40             : {
      41         175 :         *task_thread_info(p) = *task_thread_info(org);
      42         175 :         task_thread_info(p)->task = p;
      43             : }
      44             : 
      45             : /*
      46             :  * Return the address of the last usable long on the stack.
      47             :  *
      48             :  * When the stack grows down, this is just above the thread
      49             :  * info struct. Going any lower will corrupt the threadinfo.
      50             :  *
      51             :  * When the stack grows up, this is the highest address.
      52             :  * Beyond that position, we corrupt data on the next page.
      53             :  */
      54             : static inline unsigned long *end_of_stack(struct task_struct *p)
      55             : {
      56             : #ifdef CONFIG_STACK_GROWSUP
      57             :         return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
      58             : #else
      59             :         return (unsigned long *)(task_thread_info(p) + 1);
      60             : #endif
      61             : }
      62             : 
      63             : #endif
      64             : 
      65             : #ifdef CONFIG_THREAD_INFO_IN_TASK
      66             : static inline void *try_get_task_stack(struct task_struct *tsk)
      67             : {
      68             :         return refcount_inc_not_zero(&tsk->stack_refcount) ?
      69             :                 task_stack_page(tsk) : NULL;
      70             : }
      71             : 
      72             : extern void put_task_stack(struct task_struct *tsk);
      73             : #else
      74             : static inline void *try_get_task_stack(struct task_struct *tsk)
      75             : {
      76             :         return task_stack_page(tsk);
      77             : }
      78             : 
      79             : static inline void put_task_stack(struct task_struct *tsk) {}
      80             : #endif
      81             : 
      82             : void exit_task_stack_account(struct task_struct *tsk);
      83             : 
      84             : #define task_stack_end_corrupted(task) \
      85             :                 (*(end_of_stack(task)) != STACK_END_MAGIC)
      86             : 
      87             : static inline int object_is_on_stack(const void *obj)
      88             : {
      89           0 :         void *stack = task_stack_page(current);
      90             : 
      91           0 :         return (obj >= stack) && (obj < (stack + THREAD_SIZE));
      92             : }
      93             : 
      94             : extern void thread_stack_cache_init(void);
      95             : 
      96             : #ifdef CONFIG_DEBUG_STACK_USAGE
      97             : static inline unsigned long stack_not_used(struct task_struct *p)
      98             : {
      99             :         unsigned long *n = end_of_stack(p);
     100             : 
     101             :         do {    /* Skip over canary */
     102             : # ifdef CONFIG_STACK_GROWSUP
     103             :                 n--;
     104             : # else
     105             :                 n++;
     106             : # endif
     107             :         } while (!*n);
     108             : 
     109             : # ifdef CONFIG_STACK_GROWSUP
     110             :         return (unsigned long)end_of_stack(p) - (unsigned long)n;
     111             : # else
     112             :         return (unsigned long)n - (unsigned long)end_of_stack(p);
     113             : # endif
     114             : }
     115             : #endif
     116             : extern void set_task_stack_end_magic(struct task_struct *tsk);
     117             : 
     118             : #ifndef __HAVE_ARCH_KSTACK_END
     119             : static inline int kstack_end(void *addr)
     120             : {
     121             :         /* Reliable end of stack detection:
     122             :          * Some APM bios versions misalign the stack
     123             :          */
     124          12 :         return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
     125             : }
     126             : #endif
     127             : 
     128             : #endif /* _LINUX_SCHED_TASK_STACK_H */