1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * along with this program; if not, write to the Free Software
14 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
15 *
16 * Copyright (C) IBM Corporation, 2011
17 *
18 * Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
19 *          Anton Blanchard <anton@au.ibm.com>
20 */
21#include <linux/uaccess.h>
22#include <linux/hardirq.h>
23#include <asm/switch_to.h>
24
25int enter_vmx_usercopy(void)
26{
27	if (in_interrupt())
28		return 0;
29
30	/* This acts as preempt_disable() as well and will make
31	 * enable_kernel_altivec(). We need to disable page faults
32	 * as they can call schedule and thus make us lose the VMX
33	 * context. So on page faults, we just fail which will cause
34	 * a fallback to the normal non-vmx copy.
35	 */
36	pagefault_disable();
37
38	enable_kernel_altivec();
39
40	return 1;
41}
42
43/*
44 * This function must return 0 because we tail call optimise when calling
45 * from __copy_tofrom_user_power7 which returns 0 on success.
46 */
47int exit_vmx_usercopy(void)
48{
49	pagefault_enable();
50	return 0;
51}
52
53int enter_vmx_copy(void)
54{
55	if (in_interrupt())
56		return 0;
57
58	preempt_disable();
59
60	enable_kernel_altivec();
61
62	return 1;
63}
64
65/*
66 * All calls to this function will be optimised into tail calls. We are
67 * passed a pointer to the destination which we return as required by a
68 * memcpy implementation.
69 */
70void *exit_vmx_copy(void *dest)
71{
72	preempt_enable();
73	return dest;
74}
75