a422084abb
KMSAN enables the use of LLVM's MemorySanitizer in the kernel. This enables precise detection of uses of uninitialized memory. As with KASAN, this feature has substantial runtime overhead and is intended to be used as part of some automated testing regime. The runtime maintains a pair of shadow maps. One is used to track the state of memory in the kernel map at bit-granularity: a bit in the kernel map is initialized when the corresponding shadow bit is clear, and is uninitialized otherwise. The second shadow map stores information about the origin of uninitialized regions of the kernel map, simplifying debugging. KMSAN relies on being able to intercept certain functions which cannot be instrumented by the compiler. KMSAN thus implements interceptors which manually update shadow state and in some cases explicitly check for uninitialized bytes. For instance, all calls to copyout() are subject to such checks. The runtime exports several functions which can be used to verify the shadow map for a given buffer. Helpers provide the same functionality for a few structures commonly used for I/O, such as CAM CCBs, BIOs and mbufs. These are handy when debugging a KMSAN report whose proximate and root causes are far away from each other. Obtained from: NetBSD Sponsored by: The FreeBSD Foundation
85 lines
2.7 KiB
C
85 lines
2.7 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2021 The FreeBSD Foundation
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*
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* This software was developed by Mark Johnston under sponsorship from the
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* FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _MACHINE_MSAN_H_
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#define _MACHINE_MSAN_H_
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#ifdef KMSAN
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_page.h>
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#include <machine/vmparam.h>
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typedef uint32_t msan_orig_t;
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/*
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* Our 32-bit origin cells encode a 2-bit type and 30-bit pointer. The pointer
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* is compressed by making it a positive offset relative to KERNBASE.
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*/
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#define KMSAN_ORIG_TYPE_SHIFT 30u
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#define KMSAN_ORIG_PTR_MASK ((1u << KMSAN_ORIG_TYPE_SHIFT) - 1)
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static inline msan_orig_t
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kmsan_md_orig_encode(int type, uintptr_t ptr)
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{
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return ((type << KMSAN_ORIG_TYPE_SHIFT) |
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((ptr & KMSAN_ORIG_PTR_MASK)));
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}
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static inline void
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kmsan_md_orig_decode(msan_orig_t orig, int *type, uintptr_t *ptr)
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{
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*type = orig >> KMSAN_ORIG_TYPE_SHIFT;
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*ptr = (orig & KMSAN_ORIG_PTR_MASK) | KERNBASE;
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}
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static inline vm_offset_t
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kmsan_md_addr_to_shad(vm_offset_t addr)
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{
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return (addr - VM_MIN_KERNEL_ADDRESS + KMSAN_SHAD_MIN_ADDRESS);
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}
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static inline vm_offset_t
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kmsan_md_addr_to_orig(vm_offset_t addr)
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{
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return (addr - VM_MIN_KERNEL_ADDRESS + KMSAN_ORIG_MIN_ADDRESS);
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}
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static inline bool
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kmsan_md_unsupported(vm_offset_t addr)
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{
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return (addr < VM_MIN_KERNEL_ADDRESS || addr >= KERNBASE);
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}
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#endif /* KMSAN */
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#endif /* !_MACHINE_MSAN_H_ */
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