LXR linux/include/linux/sched/task

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