include/linux/ptrace.h - arm/linux-arm64-legacy - Git at Google

 #ifndef _LINUX_PTRACE_H
 #define _LINUX_PTRACE_H
 /* ptrace.h */
 /* structs and defines to help the user use the ptrace system call. */

 /* has the defines to get at the registers. */

 #define PTRACE_TRACEME		   0
 #define PTRACE_PEEKTEXT		   1
 #define PTRACE_PEEKDATA		   2
 #define PTRACE_PEEKUSR		   3
 #define PTRACE_POKETEXT		   4
 #define PTRACE_POKEDATA		   5
 #define PTRACE_POKEUSR		   6
 #define PTRACE_CONT		   7
 #define PTRACE_KILL		   8
 #define PTRACE_SINGLESTEP	   9

 #define PTRACE_ATTACH		  16
 #define PTRACE_DETACH		  17

 #define PTRACE_SYSCALL		  24

 /* 0x4200-0x4300 are reserved for architecture-independent additions.  */
 #define PTRACE_SETOPTIONS	0x4200
 #define PTRACE_GETEVENTMSG	0x4201
 #define PTRACE_GETSIGINFO	0x4202
 #define PTRACE_SETSIGINFO	0x4203

 /*
  * Generic ptrace interface that exports the architecture specific regsets
  * using the corresponding NT_* types (which are also used in the core dump).
  * Please note that the NT_PRSTATUS note type in a core dump contains a full
  * 'struct elf_prstatus'. But the user_regset for NT_PRSTATUS contains just the
  * elf_gregset_t that is the pr_reg field of 'struct elf_prstatus'. For all the
  * other user_regset flavors, the user_regset layout and the ELF core dump note
  * payload are exactly the same layout.
  *
  * This interface usage is as follows:
  *	struct iovec iov = { buf, len};
  *
  *	ret = ptrace(PTRACE_GETREGSET/PTRACE_SETREGSET, pid, NT_XXX_TYPE, &iov);
  *
  * On the successful completion, iov.len will be updated by the kernel,
  * specifying how much the kernel has written/read to/from the user's iov.buf.
  */
 #define PTRACE_GETREGSET	0x4204
 #define PTRACE_SETREGSET	0x4205

 /* options set using PTRACE_SETOPTIONS */
 #define PTRACE_O_TRACESYSGOOD	0x00000001
 #define PTRACE_O_TRACEFORK	0x00000002
 #define PTRACE_O_TRACEVFORK	0x00000004
 #define PTRACE_O_TRACECLONE	0x00000008
 #define PTRACE_O_TRACEEXEC	0x00000010
 #define PTRACE_O_TRACEVFORKDONE	0x00000020
 #define PTRACE_O_TRACEEXIT	0x00000040

 #define PTRACE_O_MASK		0x0000007f

 /* Wait extended result codes for the above trace options.  */
 #define PTRACE_EVENT_FORK	1
 #define PTRACE_EVENT_VFORK	2
 #define PTRACE_EVENT_CLONE	3
 #define PTRACE_EVENT_EXEC	4
 #define PTRACE_EVENT_VFORK_DONE	5
 #define PTRACE_EVENT_EXIT	6

 #include <asm/ptrace.h>

 #ifdef __KERNEL__
 /*
  * 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_PTRACED	0x00000001
 #define PT_DTRACE	0x00000002	/* delayed trace (used on m68k, i386) */
 #define PT_TRACESYSGOOD	0x00000004
 #define PT_PTRACE_CAP	0x00000008	/* ptracer can follow suid-exec */
 #define PT_TRACE_FORK	0x00000010
 #define PT_TRACE_VFORK	0x00000020
 #define PT_TRACE_CLONE	0x00000040
 #define PT_TRACE_EXEC	0x00000080
 #define PT_TRACE_VFORK_DONE	0x00000100
 #define PT_TRACE_EXIT	0x00000200

 #define PT_TRACE_MASK	0x000003f4

 /* 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)

 #include <linux/compiler.h>		/* For unlikely.  */
 #include <linux/sched.h>		/* For struct task_struct.  */


 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_check_attach(struct task_struct *task, int kill);
 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);
 #define PTRACE_MODE_READ   1
 #define PTRACE_MODE_ATTACH 2
 /* Returns 0 on success, -errno on denial. */
 extern int __ptrace_may_access(struct task_struct *task, unsigned int mode);
 /* 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 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);

 /**
  * task_ptrace - return %PT_* flags that apply to a task
  * @task:	pointer to &task_struct in question
  *
  * Returns the %PT_* flags that apply to @task.
  */
 static inline int task_ptrace(struct task_struct *task)
 {
 	return task->ptrace;
 }

 /**
  * ptrace_event - possibly stop for a ptrace event notification
  * @mask:	%PT_* bit to check in @current->ptrace
  * @event:	%PTRACE_EVENT_* value to report if @mask is set
  * @message:	value for %PTRACE_GETEVENTMSG to return
  *
  * This checks the @mask bit to see if ptrace wants stops for this event.
  * If so we stop, reporting @event and @message to the ptrace parent.
  *
  * Returns nonzero if we did a ptrace notification, zero if not.
  *
  * Called without locks.
  */
 static inline int ptrace_event(int mask, int event, unsigned long message)
 {
 	if (mask && likely(!(current->ptrace & mask)))
 		return 0;
 	current->ptrace_message = message;
 	ptrace_notify((event << 8) | SIGTRAP);
 	return 1;
 }

 /**
  * 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->parent = child->real_parent;
 	child->ptrace = 0;
 	if (unlikely(ptrace) && (current->ptrace & PT_PTRACED)) {
 		child->ptrace = current->ptrace;
 		__ptrace_link(child, current->parent);
 	}
 }

 /**
  * 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

 /*
  * <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.
  */
 #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

 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

 #endif
	#ifndef _LINUX_PTRACE_H
	#define _LINUX_PTRACE_H
	/* ptrace.h */
	/* structs and defines to help the user use the ptrace system call. */

	/* has the defines to get at the registers. */

	#define PTRACE_TRACEME 0
	#define PTRACE_PEEKTEXT 1
	#define PTRACE_PEEKDATA 2
	#define PTRACE_PEEKUSR 3
	#define PTRACE_POKETEXT 4
	#define PTRACE_POKEDATA 5
	#define PTRACE_POKEUSR 6
	#define PTRACE_CONT 7
	#define PTRACE_KILL 8
	#define PTRACE_SINGLESTEP 9

	#define PTRACE_ATTACH 16
	#define PTRACE_DETACH 17

	#define PTRACE_SYSCALL 24

	/* 0x4200-0x4300 are reserved for architecture-independent additions. */
	#define PTRACE_SETOPTIONS 0x4200
	#define PTRACE_GETEVENTMSG 0x4201
	#define PTRACE_GETSIGINFO 0x4202
	#define PTRACE_SETSIGINFO 0x4203

	/*
	* Generic ptrace interface that exports the architecture specific regsets
	* using the corresponding NT_* types (which are also used in the core dump).
	* Please note that the NT_PRSTATUS note type in a core dump contains a full
	* 'struct elf_prstatus'. But the user_regset for NT_PRSTATUS contains just the
	* elf_gregset_t that is the pr_reg field of 'struct elf_prstatus'. For all the
	* other user_regset flavors, the user_regset layout and the ELF core dump note
	* payload are exactly the same layout.
	*
	* This interface usage is as follows:
	* struct iovec iov = { buf, len};
	*
	* ret = ptrace(PTRACE_GETREGSET/PTRACE_SETREGSET, pid, NT_XXX_TYPE, &iov);
	*
	* On the successful completion, iov.len will be updated by the kernel,
	* specifying how much the kernel has written/read to/from the user's iov.buf.
	*/
	#define PTRACE_GETREGSET 0x4204
	#define PTRACE_SETREGSET 0x4205

	/* options set using PTRACE_SETOPTIONS */
	#define PTRACE_O_TRACESYSGOOD 0x00000001
	#define PTRACE_O_TRACEFORK 0x00000002
	#define PTRACE_O_TRACEVFORK 0x00000004
	#define PTRACE_O_TRACECLONE 0x00000008
	#define PTRACE_O_TRACEEXEC 0x00000010
	#define PTRACE_O_TRACEVFORKDONE 0x00000020
	#define PTRACE_O_TRACEEXIT 0x00000040

	#define PTRACE_O_MASK 0x0000007f

	/* Wait extended result codes for the above trace options. */
	#define PTRACE_EVENT_FORK 1
	#define PTRACE_EVENT_VFORK 2
	#define PTRACE_EVENT_CLONE 3
	#define PTRACE_EVENT_EXEC 4
	#define PTRACE_EVENT_VFORK_DONE 5
	#define PTRACE_EVENT_EXIT 6

	#include <asm/ptrace.h>

	#ifdef __KERNEL__
	/*
	* 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_PTRACED 0x00000001
	#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */
	#define PT_TRACESYSGOOD 0x00000004
	#define PT_PTRACE_CAP 0x00000008 /* ptracer can follow suid-exec */
	#define PT_TRACE_FORK 0x00000010
	#define PT_TRACE_VFORK 0x00000020
	#define PT_TRACE_CLONE 0x00000040
	#define PT_TRACE_EXEC 0x00000080
	#define PT_TRACE_VFORK_DONE 0x00000100
	#define PT_TRACE_EXIT 0x00000200

	#define PT_TRACE_MASK 0x000003f4

	/* 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)

	#include <linux/compiler.h> /* For unlikely. */
	#include <linux/sched.h> /* For struct task_struct. */


	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_check_attach(struct task_struct *task, int kill);
	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);
	#define PTRACE_MODE_READ 1
	#define PTRACE_MODE_ATTACH 2
	/* Returns 0 on success, -errno on denial. */
	extern int __ptrace_may_access(struct task_struct *task, unsigned int mode);
	/* 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 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);

	/**
	* task_ptrace - return %PT_* flags that apply to a task
	* @task: pointer to &task_struct in question
	*
	* Returns the %PT_* flags that apply to @task.
	*/
	static inline int task_ptrace(struct task_struct *task)
	{
	return task->ptrace;
	}

	/**
	* ptrace_event - possibly stop for a ptrace event notification
	* @mask: %PT_* bit to check in @current->ptrace
	* @event: %PTRACE_EVENT_* value to report if @mask is set
	* @message: value for %PTRACE_GETEVENTMSG to return
	*
	* This checks the @mask bit to see if ptrace wants stops for this event.
	* If so we stop, reporting @event and @message to the ptrace parent.
	*
	* Returns nonzero if we did a ptrace notification, zero if not.
	*
	* Called without locks.
	*/
	static inline int ptrace_event(int mask, int event, unsigned long message)
	{
	if (mask && likely(!(current->ptrace & mask)))
	return 0;
	current->ptrace_message = message;
	ptrace_notify((event << 8) \| SIGTRAP);
	return 1;
	}

	/**
	* 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->parent = child->real_parent;
	child->ptrace = 0;
	if (unlikely(ptrace) && (current->ptrace & PT_PTRACED)) {
	child->ptrace = current->ptrace;
	__ptrace_link(child, current->parent);
	}
	}

	/**
	* 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

	/*
	* <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.
	*/
	#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

	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

	#endif