text: #ifndef _LINUX_PTRACE_H
  #define _LINUX_PTRACE_H
  
  #include <linux/compiler.h>		/* For unlikely.  */
  #include <linux/sched.h>		/* For struct task_struct.  */
  #include <linux/err.h>			/* for IS_ERR_VALUE */
  #include <linux/bug.h>			/* For BUG_ON.  */
  #include <linux/pid_namespace.h>	/* For task_active_pid_ns.  */
  #include <uapi/linux/ptrace.h>
  
  /*
   * Ptrace flags
   *
   * The owner ship rules for task->ptrace which holds the ptrace
   * flags is simple.  When a task is running it owns it's task->ptrace
   * flags.  When the a task is stopped the ptracer owns task->ptrace.
   */
  
  #define PT_SEIZED	0x00010000	/* SEIZE used, enable new behavior */
  #define PT_PTRACED	0x00000001
  #define PT_DTRACE	0x00000002	/* delayed trace (used on m68k, i386) */
  #define PT_PTRACE_CAP	0x00000004	/* ptracer can follow suid-exec */
  
  #define PT_OPT_FLAG_SHIFT	3
  /* PT_TRACE_* event enable flags */
  #define PT_EVENT_FLAG(event)	(1 << (PT_OPT_FLAG_SHIFT + (event)))
  #define PT_TRACESYSGOOD		PT_EVENT_FLAG(0)
  #define PT_TRACE_FORK		PT_EVENT_FLAG(PTRACE_EVENT_FORK)
  #define PT_TRACE_VFORK		PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
  #define PT_TRACE_CLONE		PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
  #define PT_TRACE_EXEC		PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
  #define PT_TRACE_VFORK_DONE	PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
  #define PT_TRACE_EXIT		PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
  #define PT_TRACE_SECCOMP	PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
  
  #define PT_EXITKILL		(PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
  #define PT_SUSPEND_SECCOMP	(PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
  
  /* single stepping state bits (used on ARM and PA-RISC) */
  #define PT_SINGLESTEP_BIT	31
  #define PT_SINGLESTEP		(1<<PT_SINGLESTEP_BIT)
  #define PT_BLOCKSTEP_BIT	30
  #define PT_BLOCKSTEP		(1<<PT_BLOCKSTEP_BIT)
  
  extern long arch_ptrace(struct task_struct *child, long request,
  			unsigned long addr, unsigned long data);
  extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  extern void ptrace_disable(struct task_struct *);
  extern int ptrace_request(struct task_struct *child, long request,
  			  unsigned long addr, unsigned long data);
  extern void ptrace_notify(int exit_code);
  extern void __ptrace_link(struct task_struct *child,
  			  struct task_struct *new_parent);
  extern void __ptrace_unlink(struct task_struct *child);
  extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
  #define PTRACE_MODE_READ	0x01
  #define PTRACE_MODE_ATTACH	0x02
  #define PTRACE_MODE_NOAUDIT	0x04
  /* Returns true on success, false on denial. */
  extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  
  static inline int ptrace_reparented(struct task_struct *child)
  {
  	return !same_thread_group(child->real_parent, child->parent);
  }
  
  static inline void ptrace_unlink(struct task_struct *child)
  {
  	if (unlikely(child->ptrace))
  		__ptrace_unlink(child);
  }
  
  int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
  			    unsigned long data);
  int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
  			    unsigned long data);
  
  /**
   * ptrace_parent - return the task that is tracing the given task
   * @task: task to consider
   *
   * Returns %NULL if no one is tracing @task, or the &struct task_struct
   * pointer to its tracer.
   *
   * Must called under rcu_read_lock().  The pointer returned might be kept
   * live only by RCU.  During exec, this may be called with task_lock() held
   * on @task, still held from when check_unsafe_exec() was called.
   */
  static inline struct task_struct *ptrace_parent(struct task_struct *task)
  {
  	if (unlikely(task->ptrace))
  		return rcu_dereference(task->parent);
  	return NULL;
  }
  
  /**
   * ptrace_event_enabled - test whether a ptrace event is enabled
   * @task: ptracee of interest
   * @event: %PTRACE_EVENT_* to test
   *
   * Test whether @event is enabled for ptracee @task.
   *
   * Returns %true if @event is enabled, %false otherwise.
   */
  static inline bool ptrace_event_enabled(struct task_struct *task, int event)
  {
  	return task->ptrace & PT_EVENT_FLAG(event);
  }
  
  /**
   * ptrace_event - possibly stop for a ptrace event notification
   * @event:	%PTRACE_EVENT_* value to report
   * @message:	value for %PTRACE_GETEVENTMSG to return
   *
   * Check whether @event is enabled and, if so, report @event and @message
   * to the ptrace parent.
   *
   * Called without locks.
   */
  static inline void ptrace_event(int event, unsigned long message)
  {
  	if (unlikely(ptrace_event_enabled(current, event))) {
  		current->ptrace_message = message;
  		ptrace_notify((event << 8) | SIGTRAP);
  	} else if (event == PTRACE_EVENT_EXEC) {
  		/* legacy EXEC report via SIGTRAP */
  		if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
  			send_sig(SIGTRAP, current, 0);
  	}
  }
  
  /**
   * ptrace_event_pid - possibly stop for a ptrace event notification
   * @event:	%PTRACE_EVENT_* value to report
   * @pid:	process identifier for %PTRACE_GETEVENTMSG to return
   *
   * Check whether @event is enabled and, if so, report @event and @pid
   * to the ptrace parent.  @pid is reported as the pid_t seen from the
   * the ptrace parent's pid namespace.
   *
   * Called without locks.
   */
  static inline void ptrace_event_pid(int event, struct pid *pid)
  {
  	/*
  	 * FIXME: There's a potential race if a ptracer in a different pid
  	 * namespace than parent attaches between computing message below and
  	 * when we acquire tasklist_lock in ptrace_stop().  If this happens,
  	 * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
  	 */
  	unsigned long message = 0;
  	struct pid_namespace *ns;
  
  	rcu_read_lock();
  	ns = task_active_pid_ns(rcu_dereference(current->parent));
  	if (ns)
  		message = pid_nr_ns(pid, ns);
  	rcu_read_unlock();
  
  	ptrace_event(event, message);
  }
  
  /**
   * ptrace_init_task - initialize ptrace state for a new child
   * @child:		new child task
   * @ptrace:		true if child should be ptrace'd by parent's tracer
   *
   * This is called immediately after adding @child to its parent's children
   * list.  @ptrace is false in the normal case, and true to ptrace @child.
   *
   * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
   */
  static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
  {
  	INIT_LIST_HEAD(&child->ptrace_entry);
  	INIT_LIST_HEAD(&child->ptraced);
  	child->jobctl = 0;
  	child->ptrace = 0;
  	child->parent = child->real_parent;
  
  	if (unlikely(ptrace) && current->ptrace) {
  		child->ptrace = current->ptrace;
  		__ptrace_link(child, current->parent);
  
  		if (child->ptrace & PT_SEIZED)
  			task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
  		else
  			sigaddset(&child->pending.signal, SIGSTOP);
  
  		set_tsk_thread_flag(child, TIF_SIGPENDING);
  	}
  }
  
  /**
   * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
   * @task:	task in %EXIT_DEAD state
   *
   * Called with write_lock(&tasklist_lock) held.
   */
  static inline void ptrace_release_task(struct task_struct *task)
  {
  	BUG_ON(!list_empty(&task->ptraced));
  	ptrace_unlink(task);
  	BUG_ON(!list_empty(&task->ptrace_entry));
  }
  
  #ifndef force_successful_syscall_return
  /*
   * System call handlers that, upon successful completion, need to return a
   * negative value should call force_successful_syscall_return() right before
   * returning.  On architectures where the syscall convention provides for a
   * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
   * others), this macro can be used to ensure that the error flag will not get
   * set.  On architectures which do not support a separate error flag, the macro
   * is a no-op and the spurious error condition needs to be filtered out by some
   * other means (e.g., in user-level, by passing an extra argument to the
   * syscall handler, or something along those lines).
   */
  #define force_successful_syscall_return() do { } while (0)
  #endif
  
  #ifndef is_syscall_success
  /*
   * On most systems we can tell if a syscall is a success based on if the retval
   * is an error value.  On some systems like ia64 and powerpc they have different
   * indicators of success/failure and must define their own.
   */
  #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
  #endif
  
  /*
   * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
   *
   * These do-nothing inlines are used when the arch does not
   * implement single-step.  The kerneldoc comments are here
   * to document the interface for all arch definitions.
   */
  
  #ifndef arch_has_single_step
  /**
   * arch_has_single_step - does this CPU support user-mode single-step?
   *
   * If this is defined, then there must be function declarations or
   * inlines for user_enable_single_step() and user_disable_single_step().
   * arch_has_single_step() should evaluate to nonzero iff the machine
   * supports instruction single-step for user mode.
   * It can be a constant or it can test a CPU feature bit.
   */
  #define arch_has_single_step()		(0)
  
  /**
   * user_enable_single_step - single-step in user-mode task
   * @task: either current or a task stopped in %TASK_TRACED
   *
   * This can only be called when arch_has_single_step() has returned nonzero.
   * Set @task so that when it returns to user mode, it will trap after the
   * next single instruction executes.  If arch_has_block_step() is defined,
   * this must clear the effects of user_enable_block_step() too.
   */
  static inline void user_enable_single_step(struct task_struct *task)
  {
  	BUG();			/* This can never be called.  */
  }
  
  /**
   * user_disable_single_step - cancel user-mode single-step
   * @task: either current or a task stopped in %TASK_TRACED
   *
   * Clear @task of the effects of user_enable_single_step() and
   * user_enable_block_step().  This can be called whether or not either
   * of those was ever called on @task, and even if arch_has_single_step()
   * returned zero.
   */
  static inline void user_disable_single_step(struct task_struct *task)
  {
  }
  #else
  extern void user_enable_single_step(struct task_struct *);
  extern void user_disable_single_step(struct task_struct *);
  #endif	/* arch_has_single_step */
  
  #ifndef arch_has_block_step
  /**
   * arch_has_block_step - does this CPU support user-mode block-step?
   *
   * If this is defined, then there must be a function declaration or inline
   * for user_enable_block_step(), and arch_has_single_step() must be defined
   * too.  arch_has_block_step() should evaluate to nonzero iff the machine
   * supports step-until-branch for user mode.  It can be a constant or it
   * can test a CPU feature bit.
   */
  #define arch_has_block_step()		(0)
  
  /**
   * user_enable_block_step - step until branch in user-mode task
   * @task: either current or a task stopped in %TASK_TRACED
   *
   * This can only be called when arch_has_block_step() has returned nonzero,
   * and will never be called when single-instruction stepping is being used.
   * Set @task so that when it returns to user mode, it will trap after the
   * next branch or trap taken.
   */
  static inline void user_enable_block_step(struct task_struct *task)
  {
  	BUG();			/* This can never be called.  */
  }
  #else
  extern void user_enable_block_step(struct task_struct *);
  #endif	/* arch_has_block_step */
  
  #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
  extern void user_single_step_siginfo(struct task_struct *tsk,
  				struct pt_regs *regs, siginfo_t *info);
  #else
  static inline void user_single_step_siginfo(struct task_struct *tsk,
  				struct pt_regs *regs, siginfo_t *info)
  {
  	memset(info, 0, sizeof(*info));
  	info->si_signo = SIGTRAP;
  }
  #endif
  
  #ifndef arch_ptrace_stop_needed
  /**
   * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
   * @code:	current->exit_code value ptrace will stop with
   * @info:	siginfo_t pointer (or %NULL) for signal ptrace will stop with
   *
   * This is called with the siglock held, to decide whether or not it's
   * necessary to release the siglock and call arch_ptrace_stop() with the
   * same @code and @info arguments.  It can be defined to a constant if
   * arch_ptrace_stop() is never required, or always is.  On machines where
   * this makes sense, it should be defined to a quick test to optimize out
   * calling arch_ptrace_stop() when it would be superfluous.  For example,
   * if the thread has not been back to user mode since the last stop, the
   * thread state might indicate that nothing needs to be done.
   *
   * This is guaranteed to be invoked once before a task stops for ptrace and
   * may include arch-specific operations necessary prior to a ptrace stop.
   */
  #define arch_ptrace_stop_needed(code, info)	(0)
  #endif
  
  #ifndef arch_ptrace_stop
  /**
   * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
   * @code:	current->exit_code value ptrace will stop with
   * @info:	siginfo_t pointer (or %NULL) for signal ptrace will stop with
   *
   * This is called with no locks held when arch_ptrace_stop_needed() has
   * just returned nonzero.  It is allowed to block, e.g. for user memory
   * access.  The arch can have machine-specific work to be done before
   * ptrace stops.  On ia64, register backing store gets written back to user
   * memory here.  Since this can be costly (requires dropping the siglock),
   * we only do it when the arch requires it for this particular stop, as
   * indicated by arch_ptrace_stop_needed().
   */
  #define arch_ptrace_stop(code, info)		do { } while (0)
  #endif
  
  #ifndef current_pt_regs
  #define current_pt_regs() task_pt_regs(current)
  #endif
  
  #ifndef ptrace_signal_deliver
  #define ptrace_signal_deliver() ((void)0)
  #endif
  
  /*
   * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
   * on *all* architectures; the only reason to have a per-arch definition
   * is optimisation.
   */
  #ifndef signal_pt_regs
  #define signal_pt_regs() task_pt_regs(current)
  #endif
  
  #ifndef current_user_stack_pointer
  #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
  #endif
  
  extern int task_current_syscall(struct task_struct *target, long *callno,
  				unsigned long args[6], unsigned int maxargs,
  				unsigned long *sp, unsigned long *pc);
  
  #endif
  