include/linux/sched/task_stack.h

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