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 13 #ifdef CONFIG_THREAD_INFO_IN_TASK 14 15 /* 16 * When accessing the stack of a non-current task that might exit, use 17 * try_get_task_stack() instead. task_stack_page will return a pointer 18 * that could get freed out from under you. 19 */ task_stack_page(const struct task_struct * task)20static __always_inline void *task_stack_page(const struct task_struct *task) 21 { 22 return task->stack; 23 } 24 25 #define setup_thread_stack(new,old) do { } while(0) 26 end_of_stack(const struct task_struct * task)27static __always_inline unsigned long *end_of_stack(const struct task_struct *task) 28 { 29 #ifdef CONFIG_STACK_GROWSUP 30 return (unsigned long *)((unsigned long)task->stack + THREAD_SIZE) - 1; 31 #else 32 return task->stack; 33 #endif 34 } 35 36 #elif !defined(__HAVE_THREAD_FUNCTIONS) 37 38 #define task_stack_page(task) ((void *)(task)->stack) 39 setup_thread_stack(struct task_struct * p,struct task_struct * org)40static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org) 41 { 42 *task_thread_info(p) = *task_thread_info(org); 43 task_thread_info(p)->task = p; 44 } 45 46 /* 47 * Return the address of the last usable long on the stack. 48 * 49 * When the stack grows down, this is just above the thread 50 * info struct. Going any lower will corrupt the threadinfo. 51 * 52 * When the stack grows up, this is the highest address. 53 * Beyond that position, we corrupt data on the next page. 54 */ end_of_stack(struct task_struct * p)55static inline unsigned long *end_of_stack(struct task_struct *p) 56 { 57 #ifdef CONFIG_STACK_GROWSUP 58 return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1; 59 #else 60 return (unsigned long *)(task_thread_info(p) + 1); 61 #endif 62 } 63 64 #endif 65 66 #ifdef CONFIG_THREAD_INFO_IN_TASK try_get_task_stack(struct task_struct * tsk)67static inline void *try_get_task_stack(struct task_struct *tsk) 68 { 69 return refcount_inc_not_zero(&tsk->stack_refcount) ? 70 task_stack_page(tsk) : NULL; 71 } 72 73 extern void put_task_stack(struct task_struct *tsk); 74 #else try_get_task_stack(struct task_struct * tsk)75static inline void *try_get_task_stack(struct task_struct *tsk) 76 { 77 return task_stack_page(tsk); 78 } 79 put_task_stack(struct task_struct * tsk)80static inline void put_task_stack(struct task_struct *tsk) {} 81 #endif 82 83 void exit_task_stack_account(struct task_struct *tsk); 84 85 #define task_stack_end_corrupted(task) \ 86 (*(end_of_stack(task)) != STACK_END_MAGIC) 87 object_is_on_stack(const void * obj)88static inline int object_is_on_stack(const void *obj) 89 { 90 void *stack = task_stack_page(current); 91 92 return (obj >= stack) && (obj < (stack + THREAD_SIZE)); 93 } 94 95 extern void thread_stack_cache_init(void); 96 97 #ifdef CONFIG_DEBUG_STACK_USAGE stack_not_used(struct task_struct * p)98static inline unsigned long stack_not_used(struct task_struct *p) 99 { 100 unsigned long *n = end_of_stack(p); 101 102 do { /* Skip over canary */ 103 # ifdef CONFIG_STACK_GROWSUP 104 n--; 105 # else 106 n++; 107 # endif 108 } while (!*n); 109 110 # ifdef CONFIG_STACK_GROWSUP 111 return (unsigned long)end_of_stack(p) - (unsigned long)n; 112 # else 113 return (unsigned long)n - (unsigned long)end_of_stack(p); 114 # endif 115 } 116 #endif 117 extern void set_task_stack_end_magic(struct task_struct *tsk); 118 119 #ifndef __HAVE_ARCH_KSTACK_END kstack_end(void * addr)120static inline int kstack_end(void *addr) 121 { 122 /* Reliable end of stack detection: 123 * Some APM bios versions misalign the stack 124 */ 125 return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*))); 126 } 127 #endif 128 129 #endif /* _LINUX_SCHED_TASK_STACK_H */ 130