Differential D29417 Diff 86307 sys/amd64/include/asan.h

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sys/amd64/include/asan.h

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				/*-
				* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
				*
				* Copyright (c) 2020 The FreeBSD Foundation
				*
				* This software was developed by Mark Johnston under sponsorship from the
				* FreeBSD Foundation.
				*
				* Redistribution and use in source and binary forms, with or without
				* modification, are permitted provided that the following conditions are
				* met:
				* 1. Redistributions of source code must retain the above copyright
				* notice, this list of conditions and the following disclaimer.
				* 2. Redistributions in binary form must reproduce the above copyright
				* notice, this list of conditions and the following disclaimer in
				* the documentation and/or other materials provided with the distribution.
				*
				* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
				* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
				* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
				* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
				* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
				* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
				* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
				* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
				* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
				* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
				* SUCH DAMAGE.
				*/

				#ifndef _MACHINE_ASAN_H_
				#define _MACHINE_ASAN_H_

				#ifdef KASAN

				#include <vm/vm.h>
				#include <vm/pmap.h>
				#include <vm/vm_page.h>
				#include <machine/vmparam.h>

				alcUnsubmitted Not Done Inline Actions This is already included by vm/pmap.h. alc: This is already included by vm/pmap.h.
				static inline vm_offset_t
				kasan_md_addr_to_shad(vm_offset_t addr)
				{
				return (((addr - VM_MIN_KERNEL_ADDRESS) >> KASAN_SHADOW_SCALE_SHIFT) +
				KASAN_MIN_ADDRESS);
				}

				static inline bool
				kasan_md_unsupported(vm_offset_t addr)
				{
				vm_offset_t kernmin;

				/*
				* The vm_page array is mapped at the beginning of the kernel map. For
				* now simply permit all accesses. We must handle the fact that KASAN
				* is initialized before the vm_page array is mapped.
				*/
				kernmin = (vm_offset_t)vm_page_array +
				vm_page_array_size * sizeof(struct vm_page);
				return (addr < kernmin \|\| addr < VM_MIN_KERNEL_ADDRESS \|\|
				kibUnsubmitted Not Done Inline Actions Why the check for < VM_MIN_KERNEL_ADDRESS is needed? From my understanding of current layout, (vm_offset_t)vm_page_array == VM_MIN_KERNEL_ADDRESS. kib: Why the check for < VM_MIN_KERNEL_ADDRESS is needed? From my understanding of current layout…
				markjAuthorUnsubmitted Done Inline Actions vm_page_array is not set until SI_SUB_VM, but we enable KASAN before starting sysinits. I tried to explain it with the comment, I'll try to make it more clear. BTW, another solution is to create a shadow map of the vm_page array in pmap_page_array_startup(). Because we do not validate accesses to vm_pages, we can use a single 4KB or 2MB physical page for the entire shadow. In fact I did it this way originally but it added some complexity, and maybe a shadow map for vm_pages could become useful some day. markj: vm_page_array is not set until SI_SUB_VM, but we enable KASAN before starting sysinits. I tried…
				kibUnsubmitted Done Inline Actions I see what you mean. It would be enough, IMO, to note that vm_page_array is initialized after first use of kasan_md_unsupported(). kib: I see what you mean. It would be enough, IMO, to note that vm_page_array is initialized after…
				addr >= VM_MAX_KERNEL_ADDRESS);
				}

				static inline void
				kasan_md_init(void)
				{
				}

				#endif /* KASAN */

				#endif /* !_MACHINE_ASAN_H_ */