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 */ task_stack_page(const struct task_struct * task)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 end_of_stack(const struct task_struct * task)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 #elif !defined(__HAVE_THREAD_FUNCTIONS) 38 39 #define task_stack_page(task) ((void *)(task)->stack) 40 setup_thread_stack(struct task_struct * p,struct task_struct * org)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 */ end_of_stack(struct task_struct * p)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 try_get_task_stack(struct task_struct * tsk)68static inline void *try_get_task_stack(struct task_struct *tsk) 69 { 70 return refcount_inc_not_zero(&tsk->stack_refcount) ? 71 task_stack_page(tsk) : NULL; 72 } 73 74 extern void put_task_stack(struct task_struct *tsk); 75 #else try_get_task_stack(struct task_struct * tsk)76static inline void *try_get_task_stack(struct task_struct *tsk) 77 { 78 return task_stack_page(tsk); 79 } 80 put_task_stack(struct task_struct * tsk)81static inline void put_task_stack(struct task_struct *tsk) {} 82 #endif 83 84 void 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 object_is_on_stack(const void * obj)89static inline int object_is_on_stack(const void *obj) 90 { 91 void *stack = task_stack_page(current); 92 93 obj = kasan_reset_tag(obj); 94 return (obj >= stack) && (obj < (stack + THREAD_SIZE)); 95 } 96 97 extern void thread_stack_cache_init(void); 98 99 #ifdef CONFIG_DEBUG_STACK_USAGE 100 unsigned long stack_not_used(struct task_struct *p); 101 #else stack_not_used(struct task_struct * p)102static inline unsigned long stack_not_used(struct task_struct *p) 103 { 104 return 0; 105 } 106 #endif 107 extern void set_task_stack_end_magic(struct task_struct *tsk); 108 109 #ifndef __HAVE_ARCH_KSTACK_END kstack_end(void * addr)110static inline int kstack_end(void *addr) 111 { 112 /* Reliable end of stack detection: 113 * Some APM bios versions misalign the stack 114 */ 115 return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*))); 116 } 117 #endif 118 119 #endif /* _LINUX_SCHED_TASK_STACK_H */ 120