initial_commit

1 files changed, 942 insertions, 0 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
new file mode 100644
index 00000000..2df11579
--- /dev/null
+++ b/kernel/ptrace.c
@@ -0,0 +1,942 @@
+/*
+ * linux/kernel/ptrace.c
+ *
+ * (C) Copyright 1999 Linus Torvalds
+ *
+ * Common interfaces for "ptrace()" which we do not want
+ * to continually duplicate across every architecture.
+ */
+
+#include <linux/capability.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/ptrace.h>
+#include <linux/security.h>
+#include <linux/signal.h>
+#include <linux/audit.h>
+#include <linux/pid_namespace.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+#include <linux/regset.h>
+#include <linux/hw_breakpoint.h>
+
+
+/*
+ * ptrace a task: make the debugger its new parent and
+ * move it to the ptrace list.
+ *
+ * Must be called with the tasklist lock write-held.
+ */
+void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
+{
+	BUG_ON(!list_empty(&child->ptrace_entry));
+	list_add(&child->ptrace_entry, &new_parent->ptraced);
+	child->parent = new_parent;
+}
+
+/**
+ * __ptrace_unlink - unlink ptracee and restore its execution state
+ * @child: ptracee to be unlinked
+ *
+ * Remove @child from the ptrace list, move it back to the original parent,
+ * and restore the execution state so that it conforms to the group stop
+ * state.
+ *
+ * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
+ * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
+ * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
+ * If the ptracer is exiting, the ptracee can be in any state.
+ *
+ * After detach, the ptracee should be in a state which conforms to the
+ * group stop.  If the group is stopped or in the process of stopping, the
+ * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
+ * up from TASK_TRACED.
+ *
+ * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
+ * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
+ * to but in the opposite direction of what happens while attaching to a
+ * stopped task.  However, in this direction, the intermediate RUNNING
+ * state is not hidden even from the current ptracer and if it immediately
+ * re-attaches and performs a WNOHANG wait(2), it may fail.
+ *
+ * CONTEXT:
+ * write_lock_irq(tasklist_lock)
+ */
+void __ptrace_unlink(struct task_struct *child)
+{
+	BUG_ON(!child->ptrace);
+
+	child->ptrace = 0;
+	child->parent = child->real_parent;
+	list_del_init(&child->ptrace_entry);
+
+	spin_lock(&child->sighand->siglock);
+
+	/*
+	 * Reinstate GROUP_STOP_PENDING if group stop is in effect and
+	 * @child isn't dead.
+	 */
+	if (!(child->flags & PF_EXITING) &&
+	    (child->signal->flags & SIGNAL_STOP_STOPPED ||
+	     child->signal->group_stop_count))
+		child->group_stop |= GROUP_STOP_PENDING;
+
+	/*
+	 * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
+	 * @child in the butt.  Note that @resume should be used iff @child
+	 * is in TASK_TRACED; otherwise, we might unduly disrupt
+	 * TASK_KILLABLE sleeps.
+	 */
+	if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
+		signal_wake_up(child, task_is_traced(child));
+
+	spin_unlock(&child->sighand->siglock);
+}
+
+/*
+ * Check that we have indeed attached to the thing..
+ */
+int ptrace_check_attach(struct task_struct *child, int kill)
+{
+	int ret = -ESRCH;
+
+	/*
+	 * We take the read lock around doing both checks to close a
+	 * possible race where someone else was tracing our child and
+	 * detached between these two checks.  After this locked check,
+	 * we are sure that this is our traced child and that can only
+	 * be changed by us so it's not changing right after this.
+	 */
+	read_lock(&tasklist_lock);
+	if ((child->ptrace & PT_PTRACED) && child->parent == current) {
+		/*
+		 * child->sighand can't be NULL, release_task()
+		 * does ptrace_unlink() before __exit_signal().
+		 */
+		spin_lock_irq(&child->sighand->siglock);
+		WARN_ON_ONCE(task_is_stopped(child));
+		if (task_is_traced(child) || kill)
+			ret = 0;
+		spin_unlock_irq(&child->sighand->siglock);
+	}
+	read_unlock(&tasklist_lock);
+
+	if (!ret && !kill)
+		ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
+
+	/* All systems go.. */
+	return ret;
+}
+
+int __ptrace_may_access(struct task_struct *task, unsigned int mode)
+{
+	const struct cred *cred = current_cred(), *tcred;
+
+	/* May we inspect the given task?
+	 * This check is used both for attaching with ptrace
+	 * and for allowing access to sensitive information in /proc.
+	 *
+	 * ptrace_attach denies several cases that /proc allows
+	 * because setting up the necessary parent/child relationship
+	 * or halting the specified task is impossible.
+	 */
+	int dumpable = 0;
+	/* Don't let security modules deny introspection */
+	if (task == current)
+		return 0;
+	rcu_read_lock();
+	tcred = __task_cred(task);
+	if (cred->user->user_ns == tcred->user->user_ns &&
+	    (cred->uid == tcred->euid &&
+	     cred->uid == tcred->suid &&
+	     cred->uid == tcred->uid  &&
+	     cred->gid == tcred->egid &&
+	     cred->gid == tcred->sgid &&
+	     cred->gid == tcred->gid))
+		goto ok;
+	if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
+		goto ok;
+	rcu_read_unlock();
+	return -EPERM;
+ok:
+	rcu_read_unlock();
+	smp_rmb();
+	if (task->mm)
+		dumpable = get_dumpable(task->mm);
+	if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
+		return -EPERM;
+
+	return security_ptrace_access_check(task, mode);
+}
+
+bool ptrace_may_access(struct task_struct *task, unsigned int mode)
+{
+	int err;
+	task_lock(task);
+	err = __ptrace_may_access(task, mode);
+	task_unlock(task);
+	return !err;
+}
+
+static int ptrace_attach(struct task_struct *task)
+{
+	bool wait_trap = false;
+	int retval;
+
+	audit_ptrace(task);
+
+	retval = -EPERM;
+	if (unlikely(task->flags & PF_KTHREAD))
+		goto out;
+	if (same_thread_group(task, current))
+		goto out;
+
+	/*
+	 * Protect exec's credential calculations against our interference;
+	 * interference; SUID, SGID and LSM creds get determined differently
+	 * under ptrace.
+	 */
+	retval = -ERESTARTNOINTR;
+	if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
+		goto out;
+
+	task_lock(task);
+	retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
+	task_unlock(task);
+	if (retval)
+		goto unlock_creds;
+
+	write_lock_irq(&tasklist_lock);
+	retval = -EPERM;
+	if (unlikely(task->exit_state))
+		goto unlock_tasklist;
+	if (task->ptrace)
+		goto unlock_tasklist;
+
+	task->ptrace = PT_PTRACED;
+	if (task_ns_capable(task, CAP_SYS_PTRACE))
+		task->ptrace |= PT_PTRACE_CAP;
+
+	__ptrace_link(task, current);
+	send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+
+	spin_lock(&task->sighand->siglock);
+
+	/*
+	 * If the task is already STOPPED, set GROUP_STOP_PENDING and
+	 * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
+	 * will be cleared if the child completes the transition or any
+	 * event which clears the group stop states happens.  We'll wait
+	 * for the transition to complete before returning from this
+	 * function.
+	 *
+	 * This hides STOPPED -> RUNNING -> TRACED transition from the
+	 * attaching thread but a different thread in the same group can
+	 * still observe the transient RUNNING state.  IOW, if another
+	 * thread's WNOHANG wait(2) on the stopped tracee races against
+	 * ATTACH, the wait(2) may fail due to the transient RUNNING.
+	 *
+	 * The following task_is_stopped() test is safe as both transitions
+	 * in and out of STOPPED are protected by siglock.
+	 */
+	if (task_is_stopped(task)) {
+		task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
+		signal_wake_up(task, 1);
+		wait_trap = true;
+	}
+
+	spin_unlock(&task->sighand->siglock);
+
+	retval = 0;
+unlock_tasklist:
+	write_unlock_irq(&tasklist_lock);
+unlock_creds:
+	mutex_unlock(&task->signal->cred_guard_mutex);
+out:
+	if (wait_trap)
+		wait_event(current->signal->wait_chldexit,
+			   !(task->group_stop & GROUP_STOP_TRAPPING));
+	return retval;
+}
+
+/**
+ * ptrace_traceme  --  helper for PTRACE_TRACEME
+ *
+ * Performs checks and sets PT_PTRACED.
+ * Should be used by all ptrace implementations for PTRACE_TRACEME.
+ */
+static int ptrace_traceme(void)
+{
+	int ret = -EPERM;
+
+	write_lock_irq(&tasklist_lock);
+	/* Are we already being traced? */
+	if (!current->ptrace) {
+		ret = security_ptrace_traceme(current->parent);
+		/*
+		 * Check PF_EXITING to ensure ->real_parent has not passed
+		 * exit_ptrace(). Otherwise we don't report the error but
+		 * pretend ->real_parent untraces us right after return.
+		 */
+		if (!ret && !(current->real_parent->flags & PF_EXITING)) {
+			current->ptrace = PT_PTRACED;
+			__ptrace_link(current, current->real_parent);
+		}
+	}
+	write_unlock_irq(&tasklist_lock);
+
+	return ret;
+}
+
+/*
+ * Called with irqs disabled, returns true if childs should reap themselves.
+ */
+static int ignoring_children(struct sighand_struct *sigh)
+{
+	int ret;
+	spin_lock(&sigh->siglock);
+	ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
+	      (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
+	spin_unlock(&sigh->siglock);
+	return ret;
+}
+
+/*
+ * Called with tasklist_lock held for writing.
+ * Unlink a traced task, and clean it up if it was a traced zombie.
+ * Return true if it needs to be reaped with release_task().
+ * (We can't call release_task() here because we already hold tasklist_lock.)
+ *
+ * If it's a zombie, our attachedness prevented normal parent notification
+ * or self-reaping.  Do notification now if it would have happened earlier.
+ * If it should reap itself, return true.
+ *
+ * If it's our own child, there is no notification to do. But if our normal
+ * children self-reap, then this child was prevented by ptrace and we must
+ * reap it now, in that case we must also wake up sub-threads sleeping in
+ * do_wait().
+ */
+static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+	__ptrace_unlink(p);
+
+	if (p->exit_state == EXIT_ZOMBIE) {
+		if (!task_detached(p) && thread_group_empty(p)) {
+			if (!same_thread_group(p->real_parent, tracer))
+				do_notify_parent(p, p->exit_signal);
+			else if (ignoring_children(tracer->sighand)) {
+				__wake_up_parent(p, tracer);
+				p->exit_signal = -1;
+			}
+		}
+		if (task_detached(p)) {
+			/* Mark it as in the process of being reaped. */
+			p->exit_state = EXIT_DEAD;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static int ptrace_detach(struct task_struct *child, unsigned int data)
+{
+	bool dead = false;
+
+	if (!valid_signal(data))
+		return -EIO;
+
+	/* Architecture-specific hardware disable .. */
+	ptrace_disable(child);
+	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+
+	write_lock_irq(&tasklist_lock);
+	/*
+	 * This child can be already killed. Make sure de_thread() or
+	 * our sub-thread doing do_wait() didn't do release_task() yet.
+	 */
+	if (child->ptrace) {
+		child->exit_code = data;
+		dead = __ptrace_detach(current, child);
+	}
+	write_unlock_irq(&tasklist_lock);
+
+	if (unlikely(dead))
+		release_task(child);
+
+	return 0;
+}
+
+/*
+ * Detach all tasks we were using ptrace on. Called with tasklist held
+ * for writing, and returns with it held too. But note it can release
+ * and reacquire the lock.
+ */
+void exit_ptrace(struct task_struct *tracer)
+	__releases(&tasklist_lock)
+	__acquires(&tasklist_lock)
+{
+	struct task_struct *p, *n;
+	LIST_HEAD(ptrace_dead);
+
+	if (likely(list_empty(&tracer->ptraced)))
+		return;
+
+	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+		if (__ptrace_detach(tracer, p))
+			list_add(&p->ptrace_entry, &ptrace_dead);
+	}
+
+	write_unlock_irq(&tasklist_lock);
+	BUG_ON(!list_empty(&tracer->ptraced));
+
+	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
+		list_del_init(&p->ptrace_entry);
+		release_task(p);
+	}
+
+	write_lock_irq(&tasklist_lock);
+}
+
+int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
+{
+	int copied = 0;
+
+	while (len > 0) {
+		char buf[128];
+		int this_len, retval;
+
+		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
+		retval = access_process_vm(tsk, src, buf, this_len, 0);
+		if (!retval) {
+			if (copied)
+				break;
+			return -EIO;
+		}
+		if (copy_to_user(dst, buf, retval))
+			return -EFAULT;
+		copied += retval;
+		src += retval;
+		dst += retval;
+		len -= retval;
+	}
+	return copied;
+}
+
+int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
+{
+	int copied = 0;
+
+	while (len > 0) {
+		char buf[128];
+		int this_len, retval;
+
+		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
+		if (copy_from_user(buf, src, this_len))
+			return -EFAULT;
+		retval = access_process_vm(tsk, dst, buf, this_len, 1);
+		if (!retval) {
+			if (copied)
+				break;
+			return -EIO;
+		}
+		copied += retval;
+		src += retval;
+		dst += retval;
+		len -= retval;
+	}
+	return copied;
+}
+
+static int ptrace_setoptions(struct task_struct *child, unsigned long data)
+{
+	child->ptrace &= ~PT_TRACE_MASK;
+
+	if (data & PTRACE_O_TRACESYSGOOD)
+		child->ptrace |= PT_TRACESYSGOOD;
+
+	if (data & PTRACE_O_TRACEFORK)
+		child->ptrace |= PT_TRACE_FORK;
+
+	if (data & PTRACE_O_TRACEVFORK)
+		child->ptrace |= PT_TRACE_VFORK;
+
+	if (data & PTRACE_O_TRACECLONE)
+		child->ptrace |= PT_TRACE_CLONE;
+
+	if (data & PTRACE_O_TRACEEXEC)
+		child->ptrace |= PT_TRACE_EXEC;
+
+	if (data & PTRACE_O_TRACEVFORKDONE)
+		child->ptrace |= PT_TRACE_VFORK_DONE;
+
+	if (data & PTRACE_O_TRACEEXIT)
+		child->ptrace |= PT_TRACE_EXIT;
+
+	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
+}
+
+static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
+{
+	unsigned long flags;
+	int error = -ESRCH;
+
+	if (lock_task_sighand(child, &flags)) {
+		error = -EINVAL;
+		if (likely(child->last_siginfo != NULL)) {
+			*info = *child->last_siginfo;
+			error = 0;
+		}
+		unlock_task_sighand(child, &flags);
+	}
+	return error;
+}
+
+static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
+{
+	unsigned long flags;
+	int error = -ESRCH;
+
+	if (lock_task_sighand(child, &flags)) {
+		error = -EINVAL;
+		if (likely(child->last_siginfo != NULL)) {
+			*child->last_siginfo = *info;
+			error = 0;
+		}
+		unlock_task_sighand(child, &flags);
+	}
+	return error;
+}
+
+
+#ifdef PTRACE_SINGLESTEP
+#define is_singlestep(request)		((request) == PTRACE_SINGLESTEP)
+#else
+#define is_singlestep(request)		0
+#endif
+
+#ifdef PTRACE_SINGLEBLOCK
+#define is_singleblock(request)		((request) == PTRACE_SINGLEBLOCK)
+#else
+#define is_singleblock(request)		0
+#endif
+
+#ifdef PTRACE_SYSEMU
+#define is_sysemu_singlestep(request)	((request) == PTRACE_SYSEMU_SINGLESTEP)
+#else
+#define is_sysemu_singlestep(request)	0
+#endif
+
+static int ptrace_resume(struct task_struct *child, long request,
+			 unsigned long data)
+{
+	if (!valid_signal(data))
+		return -EIO;
+
+	if (request == PTRACE_SYSCALL)
+		set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+	else
+		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+
+#ifdef TIF_SYSCALL_EMU
+	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
+		set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+	else
+		clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+#endif
+
+	if (is_singleblock(request)) {
+		if (unlikely(!arch_has_block_step()))
+			return -EIO;
+		user_enable_block_step(child);
+	} else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
+		if (unlikely(!arch_has_single_step()))
+			return -EIO;
+		user_enable_single_step(child);
+	} else {
+		user_disable_single_step(child);
+	}
+
+	child->exit_code = data;
+	wake_up_state(child, __TASK_TRACED);
+
+	return 0;
+}
+
+#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
+
+static const struct user_regset *
+find_regset(const struct user_regset_view *view, unsigned int type)
+{
+	const struct user_regset *regset;
+	int n;
+
+	for (n = 0; n < view->n; ++n) {
+		regset = view->regsets + n;
+		if (regset->core_note_type == type)
+			return regset;
+	}
+
+	return NULL;
+}
+
+static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
+			 struct iovec *kiov)
+{
+	const struct user_regset_view *view = task_user_regset_view(task);
+	const struct user_regset *regset = find_regset(view, type);
+	int regset_no;
+
+	if (!regset || (kiov->iov_len % regset->size) != 0)
+		return -EINVAL;
+
+	regset_no = regset - view->regsets;
+	kiov->iov_len = min(kiov->iov_len,
+			    (__kernel_size_t) (regset->n * regset->size));
+
+	if (req == PTRACE_GETREGSET)
+		return copy_regset_to_user(task, view, regset_no, 0,
+					   kiov->iov_len, kiov->iov_base);
+	else
+		return copy_regset_from_user(task, view, regset_no, 0,
+					     kiov->iov_len, kiov->iov_base);
+}
+
+#endif
+
+int ptrace_request(struct task_struct *child, long request,
+		   unsigned long addr, unsigned long data)
+{
+	int ret = -EIO;
+	siginfo_t siginfo;
+	void __user *datavp = (void __user *) data;
+	unsigned long __user *datalp = datavp;
+
+	switch (request) {
+	case PTRACE_PEEKTEXT:
+	case PTRACE_PEEKDATA:
+		return generic_ptrace_peekdata(child, addr, data);
+	case PTRACE_POKETEXT:
+	case PTRACE_POKEDATA:
+		return generic_ptrace_pokedata(child, addr, data);
+
+#ifdef PTRACE_OLDSETOPTIONS
+	case PTRACE_OLDSETOPTIONS:
+#endif
+	case PTRACE_SETOPTIONS:
+		ret = ptrace_setoptions(child, data);
+		break;
+	case PTRACE_GETEVENTMSG:
+		ret = put_user(child->ptrace_message, datalp);
+		break;
+
+	case PTRACE_GETSIGINFO:
+		ret = ptrace_getsiginfo(child, &siginfo);
+		if (!ret)
+			ret = copy_siginfo_to_user(datavp, &siginfo);
+		break;
+
+	case PTRACE_SETSIGINFO:
+		if (copy_from_user(&siginfo, datavp, sizeof siginfo))
+			ret = -EFAULT;
+		else
+			ret = ptrace_setsiginfo(child, &siginfo);
+		break;
+
+	case PTRACE_DETACH:	 /* detach a process that was attached. */
+		ret = ptrace_detach(child, data);
+		break;
+
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+	case PTRACE_GETFDPIC: {
+		struct mm_struct *mm = get_task_mm(child);
+		unsigned long tmp = 0;
+
+		ret = -ESRCH;
+		if (!mm)
+			break;
+
+		switch (addr) {
+		case PTRACE_GETFDPIC_EXEC:
+			tmp = mm->context.exec_fdpic_loadmap;
+			break;
+		case PTRACE_GETFDPIC_INTERP:
+			tmp = mm->context.interp_fdpic_loadmap;
+			break;
+		default:
+			break;
+		}
+		mmput(mm);
+
+		ret = put_user(tmp, datalp);
+		break;
+	}
+#endif
+
+#ifdef PTRACE_SINGLESTEP
+	case PTRACE_SINGLESTEP:
+#endif
+#ifdef PTRACE_SINGLEBLOCK
+	case PTRACE_SINGLEBLOCK:
+#endif
+#ifdef PTRACE_SYSEMU
+	case PTRACE_SYSEMU:
+	case PTRACE_SYSEMU_SINGLESTEP:
+#endif
+	case PTRACE_SYSCALL:
+	case PTRACE_CONT:
+		return ptrace_resume(child, request, data);
+
+	case PTRACE_KILL:
+		if (child->exit_state)	/* already dead */
+			return 0;
+		return ptrace_resume(child, request, SIGKILL);
+
+#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
+	case PTRACE_GETREGSET:
+	case PTRACE_SETREGSET:
+	{
+		struct iovec kiov;
+		struct iovec __user *uiov = datavp;
+
+		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
+			return -EFAULT;
+
+		if (__get_user(kiov.iov_base, &uiov->iov_base) ||
+		    __get_user(kiov.iov_len, &uiov->iov_len))
+			return -EFAULT;
+
+		ret = ptrace_regset(child, request, addr, &kiov);
+		if (!ret)
+			ret = __put_user(kiov.iov_len, &uiov->iov_len);
+		break;
+	}
+#endif
+	default:
+		break;
+	}
+
+	return ret;
+}
+
+static struct task_struct *ptrace_get_task_struct(pid_t pid)
+{
+	struct task_struct *child;
+
+	rcu_read_lock();
+	child = find_task_by_vpid(pid);
+	if (child)
+		get_task_struct(child);
+	rcu_read_unlock();
+
+	if (!child)
+		return ERR_PTR(-ESRCH);
+	return child;
+}
+
+#ifndef arch_ptrace_attach
+#define arch_ptrace_attach(child)	do { } while (0)
+#endif
+
+SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
+		unsigned long, data)
+{
+	struct task_struct *child;
+	long ret;
+
+	if (request == PTRACE_TRACEME) {
+		ret = ptrace_traceme();
+		if (!ret)
+			arch_ptrace_attach(current);
+		goto out;
+	}
+
+	child = ptrace_get_task_struct(pid);
+	if (IS_ERR(child)) {
+		ret = PTR_ERR(child);
+		goto out;
+	}
+
+	if (request == PTRACE_ATTACH) {
+		ret = ptrace_attach(child);
+		/*
+		 * Some architectures need to do book-keeping after
+		 * a ptrace attach.
+		 */
+		if (!ret)
+			arch_ptrace_attach(child);
+		goto out_put_task_struct;
+	}
+
+	ret = ptrace_check_attach(child, request == PTRACE_KILL);
+	if (ret < 0)
+		goto out_put_task_struct;
+
+	ret = arch_ptrace(child, request, addr, data);
+
+ out_put_task_struct:
+	put_task_struct(child);
+ out:
+	return ret;
+}
+
+int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
+			    unsigned long data)
+{
+	unsigned long tmp;
+	int copied;
+
+	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
+	if (copied != sizeof(tmp))
+		return -EIO;
+	return put_user(tmp, (unsigned long __user *)data);
+}
+
+int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
+			    unsigned long data)
+{
+	int copied;
+
+	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
+	return (copied == sizeof(data)) ? 0 : -EIO;
+}
+
+#if defined CONFIG_COMPAT
+#include <linux/compat.h>
+
+int compat_ptrace_request(struct task_struct *child, compat_long_t request,
+			  compat_ulong_t addr, compat_ulong_t data)
+{
+	compat_ulong_t __user *datap = compat_ptr(data);
+	compat_ulong_t word;
+	siginfo_t siginfo;
+	int ret;
+
+	switch (request) {
+	case PTRACE_PEEKTEXT:
+	case PTRACE_PEEKDATA:
+		ret = access_process_vm(child, addr, &word, sizeof(word), 0);
+		if (ret != sizeof(word))
+			ret = -EIO;
+		else
+			ret = put_user(word, datap);
+		break;
+
+	case PTRACE_POKETEXT:
+	case PTRACE_POKEDATA:
+		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
+		ret = (ret != sizeof(data) ? -EIO : 0);
+		break;
+
+	case PTRACE_GETEVENTMSG:
+		ret = put_user((compat_ulong_t) child->ptrace_message, datap);
+		break;
+
+	case PTRACE_GETSIGINFO:
+		ret = ptrace_getsiginfo(child, &siginfo);
+		if (!ret)
+			ret = copy_siginfo_to_user32(
+				(struct compat_siginfo __user *) datap,
+				&siginfo);
+		break;
+
+	case PTRACE_SETSIGINFO:
+		memset(&siginfo, 0, sizeof siginfo);
+		if (copy_siginfo_from_user32(
+			    &siginfo, (struct compat_siginfo __user *) datap))
+			ret = -EFAULT;
+		else
+			ret = ptrace_setsiginfo(child, &siginfo);
+		break;
+#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
+	case PTRACE_GETREGSET:
+	case PTRACE_SETREGSET:
+	{
+		struct iovec kiov;
+		struct compat_iovec __user *uiov =
+			(struct compat_iovec __user *) datap;
+		compat_uptr_t ptr;
+		compat_size_t len;
+
+		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
+			return -EFAULT;
+
+		if (__get_user(ptr, &uiov->iov_base) ||
+		    __get_user(len, &uiov->iov_len))
+			return -EFAULT;
+
+		kiov.iov_base = compat_ptr(ptr);
+		kiov.iov_len = len;
+
+		ret = ptrace_regset(child, request, addr, &kiov);
+		if (!ret)
+			ret = __put_user(kiov.iov_len, &uiov->iov_len);
+		break;
+	}
+#endif
+
+	default:
+		ret = ptrace_request(child, request, addr, data);
+	}
+
+	return ret;
+}
+
+asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
+				  compat_long_t addr, compat_long_t data)
+{
+	struct task_struct *child;
+	long ret;
+
+	if (request == PTRACE_TRACEME) {
+		ret = ptrace_traceme();
+		goto out;
+	}
+
+	child = ptrace_get_task_struct(pid);
+	if (IS_ERR(child)) {
+		ret = PTR_ERR(child);
+		goto out;
+	}
+
+	if (request == PTRACE_ATTACH) {
+		ret = ptrace_attach(child);
+		/*
+		 * Some architectures need to do book-keeping after
+		 * a ptrace attach.
+		 */
+		if (!ret)
+			arch_ptrace_attach(child);
+		goto out_put_task_struct;
+	}
+
+	ret = ptrace_check_attach(child, request == PTRACE_KILL);
+	if (!ret)
+		ret = compat_arch_ptrace(child, request, addr, data);
+
+ out_put_task_struct:
+	put_task_struct(child);
+ out:
+	return ret;
+}
+#endif	/* CONFIG_COMPAT */
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+int ptrace_get_breakpoints(struct task_struct *tsk)
+{
+	if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
+		return 0;
+
+	return -1;
+}
+
+void ptrace_put_breakpoints(struct task_struct *tsk)
+{
+	if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
+		flush_ptrace_hw_breakpoint(tsk);
+}
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */