1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCHED_TASK_STACK_H 2 #ifndef _LINUX_SCHED_TASK_STACK_H
3 #define _LINUX_SCHED_TASK_STACK_H 3 #define _LINUX_SCHED_TASK_STACK_H
4 4
5 /* 5 /*
6 * task->stack (kernel stack) handling interfa 6 * task->stack (kernel stack) handling interfaces:
7 */ 7 */
8 8
9 #include <linux/sched.h> 9 #include <linux/sched.h>
10 #include <linux/magic.h> 10 #include <linux/magic.h>
11 #include <linux/refcount.h> <<
12 11
13 #ifdef CONFIG_THREAD_INFO_IN_TASK 12 #ifdef CONFIG_THREAD_INFO_IN_TASK
14 13
15 /* 14 /*
16 * When accessing the stack of a non-current t 15 * When accessing the stack of a non-current task that might exit, use
17 * try_get_task_stack() instead. task_stack_p 16 * try_get_task_stack() instead. task_stack_page will return a pointer
18 * that could get freed out from under you. 17 * that could get freed out from under you.
19 */ 18 */
20 static __always_inline void *task_stack_page(c 19 static __always_inline void *task_stack_page(const struct task_struct *task)
21 { 20 {
22 return task->stack; 21 return task->stack;
23 } 22 }
24 23
25 #define setup_thread_stack(new,old) do { } 24 #define setup_thread_stack(new,old) do { } while(0)
26 25
27 static __always_inline unsigned long *end_of_s 26 static __always_inline unsigned long *end_of_stack(const struct task_struct *task)
28 { 27 {
29 #ifdef CONFIG_STACK_GROWSUP 28 #ifdef CONFIG_STACK_GROWSUP
30 return (unsigned long *)((unsigned lon 29 return (unsigned long *)((unsigned long)task->stack + THREAD_SIZE) - 1;
31 #else 30 #else
32 return task->stack; 31 return task->stack;
33 #endif 32 #endif
34 } 33 }
35 34
36 #elif !defined(__HAVE_THREAD_FUNCTIONS) 35 #elif !defined(__HAVE_THREAD_FUNCTIONS)
37 36
38 #define task_stack_page(task) ((void *)(task 37 #define task_stack_page(task) ((void *)(task)->stack)
39 38
40 static inline void setup_thread_stack(struct t 39 static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
41 { 40 {
42 *task_thread_info(p) = *task_thread_in 41 *task_thread_info(p) = *task_thread_info(org);
43 task_thread_info(p)->task = p; 42 task_thread_info(p)->task = p;
44 } 43 }
45 44
46 /* 45 /*
47 * Return the address of the last usable long 46 * Return the address of the last usable long on the stack.
48 * 47 *
49 * When the stack grows down, this is just abo 48 * When the stack grows down, this is just above the thread
50 * info struct. Going any lower will corrupt t 49 * info struct. Going any lower will corrupt the threadinfo.
51 * 50 *
52 * When the stack grows up, this is the highes 51 * When the stack grows up, this is the highest address.
53 * Beyond that position, we corrupt data on th 52 * Beyond that position, we corrupt data on the next page.
54 */ 53 */
55 static inline unsigned long *end_of_stack(stru 54 static inline unsigned long *end_of_stack(struct task_struct *p)
56 { 55 {
57 #ifdef CONFIG_STACK_GROWSUP 56 #ifdef CONFIG_STACK_GROWSUP
58 return (unsigned long *)((unsigned lon 57 return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
59 #else 58 #else
60 return (unsigned long *)(task_thread_i 59 return (unsigned long *)(task_thread_info(p) + 1);
61 #endif 60 #endif
62 } 61 }
63 62
64 #endif 63 #endif
65 64
66 #ifdef CONFIG_THREAD_INFO_IN_TASK 65 #ifdef CONFIG_THREAD_INFO_IN_TASK
67 static inline void *try_get_task_stack(struct 66 static inline void *try_get_task_stack(struct task_struct *tsk)
68 { 67 {
69 return refcount_inc_not_zero(&tsk->sta 68 return refcount_inc_not_zero(&tsk->stack_refcount) ?
70 task_stack_page(tsk) : NULL; 69 task_stack_page(tsk) : NULL;
71 } 70 }
72 71
73 extern void put_task_stack(struct task_struct 72 extern void put_task_stack(struct task_struct *tsk);
74 #else 73 #else
75 static inline void *try_get_task_stack(struct 74 static inline void *try_get_task_stack(struct task_struct *tsk)
76 { 75 {
77 return task_stack_page(tsk); 76 return task_stack_page(tsk);
78 } 77 }
79 78
80 static inline void put_task_stack(struct task_ 79 static inline void put_task_stack(struct task_struct *tsk) {}
81 #endif 80 #endif
82 81
83 void exit_task_stack_account(struct task_struc 82 void exit_task_stack_account(struct task_struct *tsk);
84 83
85 #define task_stack_end_corrupted(task) \ 84 #define task_stack_end_corrupted(task) \
86 (*(end_of_stack(task)) != STAC 85 (*(end_of_stack(task)) != STACK_END_MAGIC)
87 86
88 static inline int object_is_on_stack(const voi 87 static inline int object_is_on_stack(const void *obj)
89 { 88 {
90 void *stack = task_stack_page(current) 89 void *stack = task_stack_page(current);
91 90
92 return (obj >= stack) && (obj < (stack 91 return (obj >= stack) && (obj < (stack + THREAD_SIZE));
93 } 92 }
94 93
95 extern void thread_stack_cache_init(void); 94 extern void thread_stack_cache_init(void);
96 95
97 #ifdef CONFIG_DEBUG_STACK_USAGE 96 #ifdef CONFIG_DEBUG_STACK_USAGE
98 unsigned long stack_not_used(struct task_struc <<
99 #else <<
100 static inline unsigned long stack_not_used(str 97 static inline unsigned long stack_not_used(struct task_struct *p)
101 { 98 {
102 return 0; !! 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
103 } 114 }
104 #endif 115 #endif
105 extern void set_task_stack_end_magic(struct ta 116 extern void set_task_stack_end_magic(struct task_struct *tsk);
106 117
107 #ifndef __HAVE_ARCH_KSTACK_END 118 #ifndef __HAVE_ARCH_KSTACK_END
108 static inline int kstack_end(void *addr) 119 static inline int kstack_end(void *addr)
109 { 120 {
110 /* Reliable end of stack detection: 121 /* Reliable end of stack detection:
111 * Some APM bios versions misalign the 122 * Some APM bios versions misalign the stack
112 */ 123 */
113 return !(((unsigned long)addr+sizeof(v 124 return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
114 } 125 }
115 #endif 126 #endif
116 127
117 #endif /* _LINUX_SCHED_TASK_STACK_H */ 128 #endif /* _LINUX_SCHED_TASK_STACK_H */
118 129
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