1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *
4  * Copyright (C) IBM Corporation, 2011
5  *
6  * Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
7  *          Anton Blanchard <anton@au.ibm.com>
8  */
9 #include <linux/uaccess.h>
10 #include <linux/hardirq.h>
11 #include <asm/switch_to.h>
12 #include <asm/asm-prototypes.h>
13 
enter_vmx_usercopy(void)14 int enter_vmx_usercopy(void)
15 {
16 	if (in_interrupt())
17 		return 0;
18 
19 	preempt_disable();
20 	/*
21 	 * We need to disable page faults as they can call schedule and
22 	 * thus make us lose the VMX context. So on page faults, we just
23 	 * fail which will cause a fallback to the normal non-vmx copy.
24 	 */
25 	pagefault_disable();
26 
27 	enable_kernel_altivec();
28 
29 	return 1;
30 }
31 
32 /*
33  * This function must return 0 because we tail call optimise when calling
34  * from __copy_tofrom_user_power7 which returns 0 on success.
35  */
exit_vmx_usercopy(void)36 int exit_vmx_usercopy(void)
37 {
38 	disable_kernel_altivec();
39 	pagefault_enable();
40 	preempt_enable();
41 	return 0;
42 }
43 
enter_vmx_ops(void)44 int enter_vmx_ops(void)
45 {
46 	if (in_interrupt())
47 		return 0;
48 
49 	preempt_disable();
50 
51 	enable_kernel_altivec();
52 
53 	return 1;
54 }
55 
56 /*
57  * All calls to this function will be optimised into tail calls. We are
58  * passed a pointer to the destination which we return as required by a
59  * memcpy implementation.
60  */
exit_vmx_ops(void * dest)61 void *exit_vmx_ops(void *dest)
62 {
63 	disable_kernel_altivec();
64 	preempt_enable();
65 	return dest;
66 }
67