arch/powerpc/lib/vmx-helper.c

   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
  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  */
  36 int exit_vmx_usercopy(void)
  37 {
  38         disable_kernel_altivec();
  39         pagefault_enable();
  40         preempt_enable();
  41         return 0;
  42 }
  43
  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  */
  61 void *exit_vmx_ops(void *dest)
  62 {
  63         disable_kernel_altivec();
  64         preempt_enable();
  65         return dest;
  66 }