long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
	long i, ret;
	unsigned ui;

	switch (request) {
	/* when I and D space are separate, these will need to be fixed. */
	case PTRACE_PEEKTEXT: /* read word at location addr. */ 
	case PTRACE_PEEKDATA:
		ret = generic_ptrace_peekdata(child, addr, data);
		break;

	/* read the word at location addr in the USER area. */
	case PTRACE_PEEKUSR: {
		unsigned long tmp;

		ret = -EIO;
		if ((addr & 7) ||
		    addr > sizeof(struct user) - 7)
			break;

		switch (addr) { 
		case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
			tmp = getreg(child, addr);
			break;
		case offsetof(struct user, u_debugreg[0]):
			tmp = child->thread.debugreg0;
			break;
		case offsetof(struct user, u_debugreg[1]):
			tmp = child->thread.debugreg1;
			break;
		case offsetof(struct user, u_debugreg[2]):
			tmp = child->thread.debugreg2;
			break;
		case offsetof(struct user, u_debugreg[3]):
			tmp = child->thread.debugreg3;
			break;
		case offsetof(struct user, u_debugreg[6]):
			tmp = child->thread.debugreg6;
			break;
		case offsetof(struct user, u_debugreg[7]):
			tmp = child->thread.debugreg7;
			break;
		default:
			tmp = 0;
			break;
		}
		ret = put_user(tmp,(unsigned long __user *) data);
		break;
	}

	/* when I and D space are separate, this will have to be fixed. */
	case PTRACE_POKETEXT: /* write the word at location addr. */
	case PTRACE_POKEDATA:
		ret = generic_ptrace_pokedata(child, addr, data);
		break;

	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
	{
		int dsize = test_tsk_thread_flag(child, TIF_IA32) ? 3 : 7;
		ret = -EIO;
		if ((addr & 7) ||
		    addr > sizeof(struct user) - 7)
			break;

		switch (addr) { 
		case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
			ret = putreg(child, addr, data);
			break;
		/* Disallows to set a breakpoint into the vsyscall */
		case offsetof(struct user, u_debugreg[0]):
			if (data >= TASK_SIZE_OF(child) - dsize) break;
			child->thread.debugreg0 = data;
			ret = 0;
			break;
		case offsetof(struct user, u_debugreg[1]):
			if (data >= TASK_SIZE_OF(child) - dsize) break;
			child->thread.debugreg1 = data;
			ret = 0;
			break;
		case offsetof(struct user, u_debugreg[2]):
			if (data >= TASK_SIZE_OF(child) - dsize) break;
			child->thread.debugreg2 = data;
			ret = 0;
			break;
		case offsetof(struct user, u_debugreg[3]):
			if (data >= TASK_SIZE_OF(child) - dsize) break;
			child->thread.debugreg3 = data;
			ret = 0;
			break;
		case offsetof(struct user, u_debugreg[6]):
				  if (data >> 32)
				break; 
			child->thread.debugreg6 = data;
			ret = 0;
			break;
		case offsetof(struct user, u_debugreg[7]):
			/* See arch/i386/kernel/ptrace.c for an explanation of
			 * this awkward check.*/
			data &= ~DR_CONTROL_RESERVED;
			for(i=0; i<4; i++)
				if ((0x5554 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
					break;
			if (i == 4) {
			  child->thread.debugreg7 = data;
			  if (data)
			  	set_tsk_thread_flag(child, TIF_DEBUG);
			  else
			  	clear_tsk_thread_flag(child, TIF_DEBUG);
			  ret = 0;
		  	}
		  break;
		}
		break;
	}
	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
	case PTRACE_CONT:    /* restart after signal. */

		ret = -EIO;
		if (!valid_signal(data))
			break;
		if (request == PTRACE_SYSCALL)
			set_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
		else
			clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
		clear_tsk_thread_flag(child, TIF_SINGLESTEP);
		child->exit_code = data;
		/* make sure the single step bit is not set. */
		clear_singlestep(child);
		wake_up_process(child);
		ret = 0;
		break;

#ifdef CONFIG_IA32_EMULATION
		/* This makes only sense with 32bit programs. Allow a
		   64bit debugger to fully examine them too. Better
		   don't use it against 64bit processes, use
		   PTRACE_ARCH_PRCTL instead. */
	case PTRACE_SET_THREAD_AREA: {
		struct user_desc __user *p;
		int old; 
		p = (struct user_desc __user *)data;
		get_user(old,  &p->entry_number); 
		put_user(addr, &p->entry_number);
		ret = do_set_thread_area(&child->thread, p);
		put_user(old,  &p->entry_number); 
		break;
	case PTRACE_GET_THREAD_AREA:
		p = (struct user_desc __user *)data;
		get_user(old,  &p->entry_number); 
		put_user(addr, &p->entry_number);
		ret = do_get_thread_area(&child->thread, p);
		put_user(old,  &p->entry_number); 
		break;
	} 
#endif
		/* normal 64bit interface to access TLS data. 
		   Works just like arch_prctl, except that the arguments
		   are reversed. */
	case PTRACE_ARCH_PRCTL: 
		ret = do_arch_prctl(child, data, addr);
		break;

/*
 * make the child exit.  Best I can do is send it a sigkill. 
 * perhaps it should be put in the status that it wants to 
 * exit.
 */
	case PTRACE_KILL:
		ret = 0;
		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
			break;
		clear_tsk_thread_flag(child, TIF_SINGLESTEP);
		child->exit_code = SIGKILL;
		/* make sure the single step bit is not set. */
		clear_singlestep(child);
		wake_up_process(child);
		break;

	case PTRACE_SINGLESTEP:    /* set the trap flag. */
		ret = -EIO;
		if (!valid_signal(data))
			break;
		clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
		set_singlestep(child);
		child->exit_code = data;
		/* give it a chance to run. */
		wake_up_process(child);
		ret = 0;
		break;

	case PTRACE_DETACH:
		/* detach a process that was attached. */
		ret = ptrace_detach(child, data);
		break;

	case PTRACE_GETREGS: { /* Get all gp regs from the child. */
	  	if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
			       sizeof(struct user_regs_struct))) {
			ret = -EIO;
			break;
		}
		ret = 0;
		for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
			ret |= __put_user(getreg(child, ui),(unsigned long __user *) data);
			data += sizeof(long);
		}
		break;
	}

	case PTRACE_SETREGS: { /* Set all gp regs in the child. */
		unsigned long tmp;
	  	if (!access_ok(VERIFY_READ, (unsigned __user *)data,
			       sizeof(struct user_regs_struct))) {
			ret = -EIO;
			break;
		}
		ret = 0;
		for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
			ret = __get_user(tmp, (unsigned long __user *) data);
			if (ret)
				break;
			ret = putreg(child, ui, tmp);
			if (ret)
				break;
			data += sizeof(long);
		}
		break;
	}

	case PTRACE_GETFPREGS: { /* Get the child extended FPU state. */
		if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
			       sizeof(struct user_i387_struct))) {
			ret = -EIO;
			break;
		}
		ret = get_fpregs((struct user_i387_struct __user *)data, child);
		break;
	}

	case PTRACE_SETFPREGS: { /* Set the child extended FPU state. */
		if (!access_ok(VERIFY_READ, (unsigned __user *)data,
			       sizeof(struct user_i387_struct))) {
			ret = -EIO;
			break;
		}
		set_stopped_child_used_math(child);
		ret = set_fpregs(child, (struct user_i387_struct __user *)data);
		break;
	}

	default:
		ret = ptrace_request(child, request, addr, data);
		break;
	}
	return ret;
}