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 */ 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 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 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 */ 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 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 73extern void put_task_stack(struct task_struct *tsk); 74#else 75static inline void *try_get_task_stack(struct task_struct *tsk) 76{ 77 return task_stack_page(tsk); 78} 79 80static inline void put_task_stack(struct task_struct *tsk) {} 81#endif 82 83void 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 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 95extern void thread_stack_cache_init(void); 96 97#ifdef CONFIG_DEBUG_STACK_USAGE 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 117extern void set_task_stack_end_magic(struct task_struct *tsk); 118 119#ifndef __HAVE_ARCH_KSTACK_END 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