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  */
task_stack_page(const struct task_struct * task)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 
end_of_stack(const struct task_struct * task)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 
setup_thread_stack(struct task_struct * p,struct task_struct * org)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  */
end_of_stack(struct task_struct * p)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
try_get_task_stack(struct task_struct * tsk)62 static inline void *try_get_task_stack(struct task_struct *tsk)
63 {
64 	return refcount_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
try_get_task_stack(struct task_struct * tsk)70 static inline void *try_get_task_stack(struct task_struct *tsk)
71 {
72 	return task_stack_page(tsk);
73 }
74 
put_task_stack(struct task_struct * tsk)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 
object_is_on_stack(const void * obj)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
stack_not_used(struct task_struct * p)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
kstack_end(void * addr)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