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 __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
26static 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
39static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
40{
41 *task_thread_info(p) = *task_thread_info(org);
42 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 */
54static 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
66static 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
72extern void put_task_stack(struct task_struct *tsk);
73#else
74static inline void *try_get_task_stack(struct task_struct *tsk)
75{
76 return task_stack_page(tsk);
77}
78
79static inline void put_task_stack(struct task_struct *tsk) {}
80#endif
81
82void 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
87static inline int object_is_on_stack(const void *obj)
88{
89 void *stack = task_stack_page(current);
90
91 return (obj >= stack) && (obj < (stack + THREAD_SIZE));
92}
93
94extern void thread_stack_cache_init(void);
95
96#ifdef CONFIG_DEBUG_STACK_USAGE
97static 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
116extern void set_task_stack_end_magic(struct task_struct *tsk);
117
118#ifndef __HAVE_ARCH_KSTACK_END
119static inline int kstack_end(void *addr)
120{
121 /* Reliable end of stack detection:
122 * Some APM bios versions misalign the stack
123 */
124 return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
125}
126#endif
127
128#endif /* _LINUX_SCHED_TASK_STACK_H */
129

source code of linux/include/linux/sched/task_stack.h