powerpc/lib/vmx-helper.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *
0004  * Copyright (C) IBM Corporation, 2011
0005  *
0006  * Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
0007  *          Anton Blanchard <anton@au.ibm.com>
0008  */
0009 #include <linux/uaccess.h>
0010 #include <linux/hardirq.h>
0011 #include <asm/switch_to.h>
0012
0013 int enter_vmx_usercopy(void)
0014 {
0015     if (in_interrupt())
0016         return 0;
0017
0018     preempt_disable();
0019     /*
0020      * We need to disable page faults as they can call schedule and
0021      * thus make us lose the VMX context. So on page faults, we just
0022      * fail which will cause a fallback to the normal non-vmx copy.
0023      */
0024     pagefault_disable();
0025
0026     enable_kernel_altivec();
0027
0028     return 1;
0029 }
0030
0031 /*
0032  * This function must return 0 because we tail call optimise when calling
0033  * from __copy_tofrom_user_power7 which returns 0 on success.
0034  */
0035 int exit_vmx_usercopy(void)
0036 {
0037     disable_kernel_altivec();
0038     pagefault_enable();
0039     preempt_enable();
0040     return 0;
0041 }
0042
0043 int enter_vmx_ops(void)
0044 {
0045     if (in_interrupt())
0046         return 0;
0047
0048     preempt_disable();
0049
0050     enable_kernel_altivec();
0051
0052     return 1;
0053 }
0054
0055 /*
0056  * All calls to this function will be optimised into tail calls. We are
0057  * passed a pointer to the destination which we return as required by a
0058  * memcpy implementation.
0059  */
0060 void *exit_vmx_ops(void *dest)
0061 {
0062     disable_kernel_altivec();
0063     preempt_enable();
0064     return dest;
0065 }