[mirror_ubuntu-artful-kernel.git] / include / linux / ptrace.h

#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 <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)

/* 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);
#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_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.
 */
#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
Commit	Line	Data
1da177e4 LT	1	#ifndef _LINUX_PTRACE_H
1da177e4 LT	2	#define _LINUX_PTRACE_H
1da177e4	3
607ca46e DH	4	#include <linux/compiler.h> /* For unlikely. */
	5	#include <linux/sched.h> /* For struct task_struct. */
	6	#include <linux/err.h> /* for IS_ERR_VALUE */
	7	#include <linux/bug.h> /* For BUG_ON. */
	8	#include <uapi/linux/ptrace.h>
1da177e4	9
1da177e4 LT	10	/*
1da177e4 LT	11	* Ptrace flags
260ea101 EB	12	*
	13	* The owner ship rules for task->ptrace which holds the ptrace
	14	* flags is simple. When a task is running it owns it's task->ptrace
	15	* flags. When the a task is stopped the ptracer owns task->ptrace.
1da177e4 LT	16	*/
1da177e4 LT	17
3544d72a	18	#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */
1da177e4 LT	19	#define PT_PTRACED 0x00000001
1da177e4 LT	20	#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */
86b6c1f3	21	#define PT_PTRACE_CAP 0x00000004 /* ptracer can follow suid-exec */
643ad838	22
86b6c1f3	23	#define PT_OPT_FLAG_SHIFT 3
643ad838	24	/* PT_TRACE_* event enable flags */
86b6c1f3 DV	25	#define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event)))
86b6c1f3 DV	26	#define PT_TRACESYSGOOD PT_EVENT_FLAG(0)
643ad838 TH	27	#define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK)
	28	#define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
	29	#define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
	30	#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
	31	#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
	32	#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
fb0fadf9	33	#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
1da177e4	34
992fb6e1 ON	35	#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
992fb6e1 ON	36
1da177e4 LT	37	/* single stepping state bits (used on ARM and PA-RISC) */
	38	#define PT_SINGLESTEP_BIT 31
	39	#define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT)
	40	#define PT_BLOCKSTEP_BIT 30
	41	#define PT_BLOCKSTEP (1<<PT_BLOCKSTEP_BIT)
	42
9b05a69e NK	43	extern long arch_ptrace(struct task_struct *child, long request,
9b05a69e NK	44	unsigned long addr, unsigned long data);
1da177e4 LT	45	extern int ptrace_readdata(struct task_struct tsk, unsigned long src, char __user dst, int len);
1da177e4 LT	46	extern int ptrace_writedata(struct task_struct tsk, char __user src, unsigned long dst, int len);
1da177e4	47	extern void ptrace_disable(struct task_struct *);
4abf9869 NK	48	extern int ptrace_request(struct task_struct *child, long request,
4abf9869 NK	49	unsigned long addr, unsigned long data);
1da177e4 LT	50	extern void ptrace_notify(int exit_code);
	51	extern void __ptrace_link(struct task_struct *child,
	52	struct task_struct *new_parent);
	53	extern void __ptrace_unlink(struct task_struct *child);
39c626ae	54	extern void exit_ptrace(struct task_struct *tracer);
69f594a3 EP	55	#define PTRACE_MODE_READ 0x01
	56	#define PTRACE_MODE_ATTACH 0x02
	57	#define PTRACE_MODE_NOAUDIT 0x04
006ebb40 SS	58	/* Returns true on success, false on denial. */
006ebb40 SS	59	extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
1da177e4	60
53b6f9fb ON	61	static inline int ptrace_reparented(struct task_struct *child)
53b6f9fb ON	62	{
0347e177	63	return !same_thread_group(child->real_parent, child->parent);
53b6f9fb	64	}
c6a47cc2	65
1da177e4 LT	66	static inline void ptrace_unlink(struct task_struct *child)
	67	{
	68	if (unlikely(child->ptrace))
	69	__ptrace_unlink(child);
	70	}
	71
4abf9869 NK	72	int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
	73	unsigned long data);
	74	int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
	75	unsigned long data);
1da177e4	76
06d98473 TH	77	/**
	78	* ptrace_parent - return the task that is tracing the given task
	79	* @task: task to consider
	80	*
	81	* Returns %NULL if no one is tracing @task, or the &struct task_struct
	82	* pointer to its tracer.
	83	*
	84	* Must called under rcu_read_lock(). The pointer returned might be kept
	85	* live only by RCU. During exec, this may be called with task_lock() held
	86	* on @task, still held from when check_unsafe_exec() was called.
	87	*/
	88	static inline struct task_struct ptrace_parent(struct task_struct task)
	89	{
	90	if (unlikely(task->ptrace))
	91	return rcu_dereference(task->parent);
	92	return NULL;
	93	}
	94
643ad838 TH	95	/**
	96	* ptrace_event_enabled - test whether a ptrace event is enabled
	97	* @task: ptracee of interest
	98	* @event: %PTRACE_EVENT_* to test
	99	*
	100	* Test whether @event is enabled for ptracee @task.
	101	*
	102	* Returns %true if @event is enabled, %false otherwise.
	103	*/
	104	static inline bool ptrace_event_enabled(struct task_struct *task, int event)
	105	{
	106	return task->ptrace & PT_EVENT_FLAG(event);
	107	}
	108
88ac2921 RM	109	/**
88ac2921 RM	110	* ptrace_event - possibly stop for a ptrace event notification
643ad838	111	* @event: %PTRACE_EVENT_* value to report
88ac2921 RM	112	* @message: value for %PTRACE_GETEVENTMSG to return
88ac2921 RM	113	*
643ad838 TH	114	* Check whether @event is enabled and, if so, report @event and @message
643ad838 TH	115	* to the ptrace parent.
88ac2921	116	*
88ac2921 RM	117	* Called without locks.
88ac2921 RM	118	*/
f3c04b93	119	static inline void ptrace_event(int event, unsigned long message)
88ac2921	120	{
f3c04b93 TH	121	if (unlikely(ptrace_event_enabled(current, event))) {
	122	current->ptrace_message = message;
	123	ptrace_notify((event << 8) \| SIGTRAP);
b1845ff5	124	} else if (event == PTRACE_EVENT_EXEC) {
f3c04b93	125	/* legacy EXEC report via SIGTRAP */
b1845ff5 ON	126	if ((current->ptrace & (PT_PTRACED\|PT_SEIZED)) == PT_PTRACED)
b1845ff5 ON	127	send_sig(SIGTRAP, current, 0);
f3c04b93	128	}
88ac2921 RM	129	}
88ac2921 RM	130
09a05394 RM	131	/**
	132	* ptrace_init_task - initialize ptrace state for a new child
	133	* @child: new child task
	134	* @ptrace: true if child should be ptrace'd by parent's tracer
	135	*
	136	* This is called immediately after adding @child to its parent's children
	137	* list. @ptrace is false in the normal case, and true to ptrace @child.
	138	*
	139	* Called with current's siglock and write_lock_irq(&tasklist_lock) held.
	140	*/
	141	static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
	142	{
	143	INIT_LIST_HEAD(&child->ptrace_entry);
	144	INIT_LIST_HEAD(&child->ptraced);
6634ae10	145	child->jobctl = 0;
09a05394	146	child->ptrace = 0;
6634ae10 ON	147	child->parent = child->real_parent;
	148
	149	if (unlikely(ptrace) && current->ptrace) {
09a05394	150	child->ptrace = current->ptrace;
c6a47cc2	151	__ptrace_link(child, current->parent);
dcace06c	152
d184d6eb ON	153	if (child->ptrace & PT_SEIZED)
	154	task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
	155	else
	156	sigaddset(&child->pending.signal, SIGSTOP);
	157
dcace06c	158	set_tsk_thread_flag(child, TIF_SIGPENDING);
09a05394 RM	159	}
	160	}
	161
dae33574 RM	162	/**
	163	* ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
	164	* @task: task in %EXIT_DEAD state
	165	*
	166	* Called with write_lock(&tasklist_lock) held.
	167	*/
	168	static inline void ptrace_release_task(struct task_struct *task)
	169	{
	170	BUG_ON(!list_empty(&task->ptraced));
	171	ptrace_unlink(task);
	172	BUG_ON(!list_empty(&task->ptrace_entry));
	173	}
	174
1da177e4 LT	175	#ifndef force_successful_syscall_return
	176	/*
	177	* System call handlers that, upon successful completion, need to return a
	178	* negative value should call force_successful_syscall_return() right before
	179	* returning. On architectures where the syscall convention provides for a
	180	* separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
	181	* others), this macro can be used to ensure that the error flag will not get
	182	* set. On architectures which do not support a separate error flag, the macro
	183	* is a no-op and the spurious error condition needs to be filtered out by some
	184	* other means (e.g., in user-level, by passing an extra argument to the
	185	* syscall handler, or something along those lines).
	186	*/
	187	#define force_successful_syscall_return() do { } while (0)
	188	#endif
	189
d7e7528b EP	190	#ifndef is_syscall_success
	191	/*
	192	* On most systems we can tell if a syscall is a success based on if the retval
	193	* is an error value. On some systems like ia64 and powerpc they have different
	194	* indicators of success/failure and must define their own.
	195	*/
	196	#define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
	197	#endif
	198
fb7fa8f1 RM	199	/*
	200	* <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
	201	*
	202	* These do-nothing inlines are used when the arch does not
	203	* implement single-step. The kerneldoc comments are here
	204	* to document the interface for all arch definitions.
	205	*/
	206
	207	#ifndef arch_has_single_step
	208	/**
	209	* arch_has_single_step - does this CPU support user-mode single-step?
	210	*
	211	* If this is defined, then there must be function declarations or
	212	* inlines for user_enable_single_step() and user_disable_single_step().
	213	* arch_has_single_step() should evaluate to nonzero iff the machine
	214	* supports instruction single-step for user mode.
	215	* It can be a constant or it can test a CPU feature bit.
	216	*/
	217	#define arch_has_single_step() (0)
	218
	219	/**
	220	* user_enable_single_step - single-step in user-mode task
	221	* @task: either current or a task stopped in %TASK_TRACED
	222	*
	223	* This can only be called when arch_has_single_step() has returned nonzero.
	224	* Set @task so that when it returns to user mode, it will trap after the
dc802c2d RM	225	* next single instruction executes. If arch_has_block_step() is defined,
dc802c2d RM	226	* this must clear the effects of user_enable_block_step() too.
fb7fa8f1 RM	227	*/
	228	static inline void user_enable_single_step(struct task_struct *task)
	229	{
	230	BUG(); /* This can never be called. */
	231	}
	232
	233	/**
	234	* user_disable_single_step - cancel user-mode single-step
	235	* @task: either current or a task stopped in %TASK_TRACED
	236	*
dc802c2d RM	237	* Clear @task of the effects of user_enable_single_step() and
	238	* user_enable_block_step(). This can be called whether or not either
	239	* of those was ever called on @task, and even if arch_has_single_step()
	240	* returned zero.
fb7fa8f1 RM	241	*/
	242	static inline void user_disable_single_step(struct task_struct *task)
	243	{
	244	}
dacbe41f CH	245	#else
	246	extern void user_enable_single_step(struct task_struct *);
	247	extern void user_disable_single_step(struct task_struct *);
fb7fa8f1 RM	248	#endif /* arch_has_single_step */
fb7fa8f1 RM	249
dc802c2d RM	250	#ifndef arch_has_block_step
	251	/**
	252	* arch_has_block_step - does this CPU support user-mode block-step?
	253	*
	254	* If this is defined, then there must be a function declaration or inline
	255	* for user_enable_block_step(), and arch_has_single_step() must be defined
	256	* too. arch_has_block_step() should evaluate to nonzero iff the machine
	257	* supports step-until-branch for user mode. It can be a constant or it
	258	* can test a CPU feature bit.
	259	*/
5b88abbf	260	#define arch_has_block_step() (0)
dc802c2d RM	261
	262	/**
	263	* user_enable_block_step - step until branch in user-mode task
	264	* @task: either current or a task stopped in %TASK_TRACED
	265	*
	266	* This can only be called when arch_has_block_step() has returned nonzero,
	267	* and will never be called when single-instruction stepping is being used.
	268	* Set @task so that when it returns to user mode, it will trap after the
	269	* next branch or trap taken.
	270	*/
	271	static inline void user_enable_block_step(struct task_struct *task)
	272	{
	273	BUG(); /* This can never be called. */
	274	}
dacbe41f CH	275	#else
dacbe41f CH	276	extern void user_enable_block_step(struct task_struct *);
dc802c2d RM	277	#endif /* arch_has_block_step */
dc802c2d RM	278
85ec7fd9 ON	279	#ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
	280	extern void user_single_step_siginfo(struct task_struct *tsk,
	281	struct pt_regs regs, siginfo_t info);
	282	#else
	283	static inline void user_single_step_siginfo(struct task_struct *tsk,
	284	struct pt_regs regs, siginfo_t info)
	285	{
	286	memset(info, 0, sizeof(*info));
	287	info->si_signo = SIGTRAP;
	288	}
	289	#endif
	290
1a669c2f RM	291	#ifndef arch_ptrace_stop_needed
	292	/**
	293	* arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
	294	* @code: current->exit_code value ptrace will stop with
	295	* @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with
	296	*
	297	* This is called with the siglock held, to decide whether or not it's
	298	* necessary to release the siglock and call arch_ptrace_stop() with the
	299	* same @code and @info arguments. It can be defined to a constant if
	300	* arch_ptrace_stop() is never required, or always is. On machines where
	301	* this makes sense, it should be defined to a quick test to optimize out
	302	* calling arch_ptrace_stop() when it would be superfluous. For example,
	303	* if the thread has not been back to user mode since the last stop, the
	304	* thread state might indicate that nothing needs to be done.
	305	*/
	306	#define arch_ptrace_stop_needed(code, info) (0)
	307	#endif
	308
	309	#ifndef arch_ptrace_stop
	310	/**
	311	* arch_ptrace_stop - Do machine-specific work before stopping for ptrace
	312	* @code: current->exit_code value ptrace will stop with
	313	* @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with
	314	*
	315	* This is called with no locks held when arch_ptrace_stop_needed() has
	316	* just returned nonzero. It is allowed to block, e.g. for user memory
	317	* access. The arch can have machine-specific work to be done before
	318	* ptrace stops. On ia64, register backing store gets written back to user
	319	* memory here. Since this can be costly (requires dropping the siglock),
	320	* we only do it when the arch requires it for this particular stop, as
	321	* indicated by arch_ptrace_stop_needed().
	322	*/
	323	#define arch_ptrace_stop(code, info) do { } while (0)
	324	#endif
	325
a3460a59 AV	326	#ifndef current_pt_regs
	327	#define current_pt_regs() task_pt_regs(current)
	328	#endif
	329
4f4202fe	330	#ifndef ptrace_signal_deliver
b7f9591c	331	#define ptrace_signal_deliver() ((void)0)
4f4202fe AV	332	#endif
4f4202fe AV	333
22062a96 AV	334	/*
	335	* unlike current_pt_regs(), this one is equal to task_pt_regs(current)
	336	* on all architectures; the only reason to have a per-arch definition
	337	* is optimisation.
	338	*/
	339	#ifndef signal_pt_regs
	340	#define signal_pt_regs() task_pt_regs(current)
	341	#endif
	342
1ca97bb5 AV	343	#ifndef current_user_stack_pointer
	344	#define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
	345	#endif
	346
bbc69863 RM	347	extern int task_current_syscall(struct task_struct target, long callno,
	348	unsigned long args[6], unsigned int maxargs,
	349	unsigned long sp, unsigned long pc);
	350
1da177e4	351	#endif