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// SPDX-License-Identifier: GPL-2.0-or-later
/*
*
* Copyright (C) IBM Corporation, 2011
*
* Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
* Anton Blanchard <anton@au.ibm.com>
*/
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <asm/switch_to.h>
int enter_vmx_usercopy(void)
{
if (in_interrupt())
return 0;
preempt_disable();
/*
* We need to disable page faults as they can call schedule and
* thus make us lose the VMX context. So on page faults, we just
* fail which will cause a fallback to the normal non-vmx copy.
*/
pagefault_disable();
enable_kernel_altivec();
return 1;
}
/*
* This function must return 0 because we tail call optimise when calling
* from __copy_tofrom_user_power7 which returns 0 on success.
*/
int exit_vmx_usercopy(void)
{
disable_kernel_altivec();
pagefault_enable();
preempt_enable_no_resched();
/*
* Must never explicitly call schedule (including preempt_enable())
* while in a kuap-unlocked user copy, because the AMR register will
* not be saved and restored across context switch. However preempt
* kernels need to be preempted as soon as possible if need_resched is
* set and we are preemptible. The hack here is to schedule a
* decrementer to fire here and reschedule for us if necessary.
*/
if (IS_ENABLED(CONFIG_PREEMPT) && need_resched())
set_dec(1);
return 0;
}
int enter_vmx_ops(void)
{
if (in_interrupt())
return 0;
preempt_disable();
enable_kernel_altivec();
return 1;
}
/*
* All calls to this function will be optimised into tail calls. We are
* passed a pointer to the destination which we return as required by a
* memcpy implementation.
*/
void *exit_vmx_ops(void *dest)
{
disable_kernel_altivec();
preempt_enable();
return dest;
}
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