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 */
21static __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
28static __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
41static 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 */
56static 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
68static inline void *try_get_task_stack(struct task_struct *tsk)
69{
70 return refcount_inc_not_zero(r: &tsk->stack_refcount) ?
71 task_stack_page(task: tsk) : NULL;
72}
73
74extern void put_task_stack(struct task_struct *tsk);
75#else
76static inline void *try_get_task_stack(struct task_struct *tsk)
77{
78 return task_stack_page(tsk);
79}
80
81static inline void put_task_stack(struct task_struct *tsk) {}
82#endif
83
84void 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
89static inline int object_is_on_stack(const void *obj)
90{
91 void *stack = task_stack_page(current);
92
93 obj = kasan_reset_tag(addr: obj);
94 return (obj >= stack) && (obj < (stack + THREAD_SIZE));
95}
96
97extern void thread_stack_cache_init(void);
98
99#ifdef CONFIG_DEBUG_STACK_USAGE
100unsigned long stack_not_used(struct task_struct *p);
101#else
102static inline unsigned long stack_not_used(struct task_struct *p)
103{
104 return 0;
105}
106#endif
107extern void set_task_stack_end_magic(struct task_struct *tsk);
108
109static inline int kstack_end(void *addr)
110{
111 /* Reliable end of stack detection:
112 * Some APM bios versions misalign the stack
113 */
114 return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
115}
116
117#endif /* _LINUX_SCHED_TASK_STACK_H */
118

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

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