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