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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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dc4fbba11e
The enable_kernel_*() functions leave the relevant MSR bits enabled until we exit the kernel sometime later. Create disable versions that wrap the kernel use of FP, Altivec VSX or SPE. While we don't want to disable it normally for performance reasons (MSR writes are slow), it will be used for a debug boot option that does this and catches bad uses in other areas of the kernel. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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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();
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return 0;
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}
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int enter_vmx_copy(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_copy(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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