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 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 inline unsigned long *end_of_stack(const struct task_struct *task)
28 { 27 {
29 #ifdef CONFIG_STACK_GROWSUP <<
30 return (unsigned long *)((unsigned lon <<
31 #else <<
32 return task->stack; 28 return task->stack;
33 #endif <<
34 } 29 }
35 30
36 #elif !defined(__HAVE_THREAD_FUNCTIONS) 31 #elif !defined(__HAVE_THREAD_FUNCTIONS)
37 32
38 #define task_stack_page(task) ((void *)(task 33 #define task_stack_page(task) ((void *)(task)->stack)
39 34
40 static inline void setup_thread_stack(struct t 35 static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
41 { 36 {
42 *task_thread_info(p) = *task_thread_in 37 *task_thread_info(p) = *task_thread_info(org);
43 task_thread_info(p)->task = p; 38 task_thread_info(p)->task = p;
44 } 39 }
45 40
46 /* 41 /*
47 * Return the address of the last usable long 42 * Return the address of the last usable long on the stack.
48 * 43 *
49 * When the stack grows down, this is just abo 44 * When the stack grows down, this is just above the thread
50 * info struct. Going any lower will corrupt t 45 * info struct. Going any lower will corrupt the threadinfo.
51 * 46 *
52 * When the stack grows up, this is the highes 47 * When the stack grows up, this is the highest address.
53 * Beyond that position, we corrupt data on th 48 * Beyond that position, we corrupt data on the next page.
54 */ 49 */
55 static inline unsigned long *end_of_stack(stru 50 static inline unsigned long *end_of_stack(struct task_struct *p)
56 { 51 {
57 #ifdef CONFIG_STACK_GROWSUP 52 #ifdef CONFIG_STACK_GROWSUP
58 return (unsigned long *)((unsigned lon 53 return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
59 #else 54 #else
60 return (unsigned long *)(task_thread_i 55 return (unsigned long *)(task_thread_info(p) + 1);
61 #endif 56 #endif
62 } 57 }
63 58
64 #endif 59 #endif
65 60
66 #ifdef CONFIG_THREAD_INFO_IN_TASK 61 #ifdef CONFIG_THREAD_INFO_IN_TASK
67 static inline void *try_get_task_stack(struct 62 static inline void *try_get_task_stack(struct task_struct *tsk)
68 { 63 {
69 return refcount_inc_not_zero(&tsk->sta 64 return refcount_inc_not_zero(&tsk->stack_refcount) ?
70 task_stack_page(tsk) : NULL; 65 task_stack_page(tsk) : NULL;
71 } 66 }
72 67
73 extern void put_task_stack(struct task_struct 68 extern void put_task_stack(struct task_struct *tsk);
74 #else 69 #else
75 static inline void *try_get_task_stack(struct 70 static inline void *try_get_task_stack(struct task_struct *tsk)
76 { 71 {
77 return task_stack_page(tsk); 72 return task_stack_page(tsk);
78 } 73 }
79 74
80 static inline void put_task_stack(struct task_ 75 static inline void put_task_stack(struct task_struct *tsk) {}
81 #endif 76 #endif
82 77
83 void exit_task_stack_account(struct task_struc <<
84 <<
85 #define task_stack_end_corrupted(task) \ 78 #define task_stack_end_corrupted(task) \
86 (*(end_of_stack(task)) != STAC 79 (*(end_of_stack(task)) != STACK_END_MAGIC)
87 80
88 static inline int object_is_on_stack(const voi 81 static inline int object_is_on_stack(const void *obj)
89 { 82 {
90 void *stack = task_stack_page(current) 83 void *stack = task_stack_page(current);
91 84
92 return (obj >= stack) && (obj < (stack 85 return (obj >= stack) && (obj < (stack + THREAD_SIZE));
93 } 86 }
94 87
95 extern void thread_stack_cache_init(void); 88 extern void thread_stack_cache_init(void);
96 89
97 #ifdef CONFIG_DEBUG_STACK_USAGE 90 #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 91 static inline unsigned long stack_not_used(struct task_struct *p)
101 { 92 {
102 return 0; !! 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
103 } 108 }
104 #endif 109 #endif
105 extern void set_task_stack_end_magic(struct ta 110 extern void set_task_stack_end_magic(struct task_struct *tsk);
106 111
107 #ifndef __HAVE_ARCH_KSTACK_END 112 #ifndef __HAVE_ARCH_KSTACK_END
108 static inline int kstack_end(void *addr) 113 static inline int kstack_end(void *addr)
109 { 114 {
110 /* Reliable end of stack detection: 115 /* Reliable end of stack detection:
111 * Some APM bios versions misalign the 116 * Some APM bios versions misalign the stack
112 */ 117 */
113 return !(((unsigned long)addr+sizeof(v 118 return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
114 } 119 }
115 #endif 120 #endif
116 121
117 #endif /* _LINUX_SCHED_TASK_STACK_H */ 122 #endif /* _LINUX_SCHED_TASK_STACK_H */
118 123
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