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42aa12e74e
The comm page which is mapped into the guest kernel address space at 0x0 has the unfortunate side effect of allowing guest kernel NULL pointer dereferences to succeed. The only constraint on this address is that it must be within 32KiB of 0x0, so that single lw/sw instructions (which have 16-bit signed offset fields) can be used to access it, using the zero register as a base. So lets move the comm page as high as possible within that constraint so that 0x0 can be left unmapped, at least for page sizes < 32KiB. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
34 lines
886 B
C
34 lines
886 B
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* commpage, currently used for Virtual COP0 registers.
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* Mapped into the guest kernel @ KVM_GUEST_COMMPAGE_ADDR.
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*
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* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
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* Authors: Sanjay Lal <sanjayl@kymasys.com>
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*/
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#include <linux/errno.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/vmalloc.h>
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#include <linux/fs.h>
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#include <linux/bootmem.h>
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#include <asm/page.h>
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#include <asm/cacheflush.h>
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#include <asm/mmu_context.h>
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#include <linux/kvm_host.h>
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#include "commpage.h"
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void kvm_mips_commpage_init(struct kvm_vcpu *vcpu)
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{
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struct kvm_mips_commpage *page = vcpu->arch.kseg0_commpage;
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/* Specific init values for fields */
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vcpu->arch.cop0 = &page->cop0;
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}
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