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 */ 19 static __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 26 static __always_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 39 static 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 */ 54 static 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 66 static 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 72 extern void put_task_stack(struct task_struct *tsk); 73 #else 74 static inline void *try_get_task_stack(struct task_struct *tsk) 75 { 76 return task_stack_page(tsk); 77 } 78 79 static inline void put_task_stack(struct task_struct *tsk) {} 80 #endif 81 82 void 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 87 static 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 94 extern void thread_stack_cache_init(void); 95 96 #ifdef CONFIG_DEBUG_STACK_USAGE 97 static 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 116 extern void set_task_stack_end_magic(struct task_struct *tsk); 117 118 #ifndef __HAVE_ARCH_KSTACK_END 119 static 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