task_stack.h

  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 */
 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
 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#else
 38
 39#define task_stack_page(task)	((void *)(task)->stack)
 40
 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 */
 56static inline unsigned long *end_of_stack(const 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
 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
 74extern void put_task_stack(struct task_struct *tsk);
 75#else
 76static inline void *try_get_task_stack(struct task_struct *tsk)
 77{
 78	return task_stack_page(tsk);
 79}
 80
 81static inline void put_task_stack(struct task_struct *tsk) {}
 82#endif
 83
 84void 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
 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
 97extern void thread_stack_cache_init(void);
 98
 99#ifdef CONFIG_DEBUG_STACK_USAGE
100unsigned long stack_not_used(struct task_struct *p);
101#else
102static inline unsigned long stack_not_used(struct task_struct *p)
103{
104	return 0;
105}
106#endif
107extern void set_task_stack_end_magic(struct task_struct *tsk);
108
109static inline int kstack_end(void *addr)
110{
111	/* Reliable end of stack detection:
112	 * Some APM bios versions misalign the stack
113	 */
114	return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
115}
116
117#endif /* _LINUX_SCHED_TASK_STACK_H */