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 */
19static 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
26static 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
35static 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 */
50static 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
62static 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
68extern void put_task_stack(struct task_struct *tsk);
69#else
70static inline void *try_get_task_stack(struct task_struct *tsk)
71{
72 return task_stack_page(tsk);
73}
74
75static 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
81static 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
88extern void thread_stack_cache_init(void);
89
90#ifdef CONFIG_DEBUG_STACK_USAGE
91static 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
110extern void set_task_stack_end_magic(struct task_struct *tsk);
111
112#ifndef __HAVE_ARCH_KSTACK_END
113static 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