cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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kasan_def.h (2726B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*
      3 *  arch/arm/include/asm/kasan_def.h
      4 *
      5 *  Copyright (c) 2018 Huawei Technologies Co., Ltd.
      6 *
      7 *  Author: Abbott Liu <liuwenliang@huawei.com>
      8 */
      9
     10#ifndef __ASM_KASAN_DEF_H
     11#define __ASM_KASAN_DEF_H
     12
     13#ifdef CONFIG_KASAN
     14
     15/*
     16 * Define KASAN_SHADOW_OFFSET,KASAN_SHADOW_START and KASAN_SHADOW_END for
     17 * the Arm kernel address sanitizer. We are "stealing" lowmem (the 4GB
     18 * addressable by a 32bit architecture) out of the virtual address
     19 * space to use as shadow memory for KASan as follows:
     20 *
     21 * +----+ 0xffffffff
     22 * |    |							\
     23 * |    | |-> Static kernel image (vmlinux) BSS and page table
     24 * |    |/
     25 * +----+ PAGE_OFFSET
     26 * |    |							\
     27 * |    | |->  Loadable kernel modules virtual address space area
     28 * |    |/
     29 * +----+ MODULES_VADDR = KASAN_SHADOW_END
     30 * |    |						\
     31 * |    | |-> The shadow area of kernel virtual address.
     32 * |    |/
     33 * +----+->  TASK_SIZE (start of kernel space) = KASAN_SHADOW_START the
     34 * |    |\   shadow address of MODULES_VADDR
     35 * |    | |
     36 * |    | |
     37 * |    | |-> The user space area in lowmem. The kernel address
     38 * |    | |   sanitizer do not use this space, nor does it map it.
     39 * |    | |
     40 * |    | |
     41 * |    | |
     42 * |    | |
     43 * |    |/
     44 * ------ 0
     45 *
     46 * 1) KASAN_SHADOW_START
     47 *   This value begins with the MODULE_VADDR's shadow address. It is the
     48 *   start of kernel virtual space. Since we have modules to load, we need
     49 *   to cover also that area with shadow memory so we can find memory
     50 *   bugs in modules.
     51 *
     52 * 2) KASAN_SHADOW_END
     53 *   This value is the 0x100000000's shadow address: the mapping that would
     54 *   be after the end of the kernel memory at 0xffffffff. It is the end of
     55 *   kernel address sanitizer shadow area. It is also the start of the
     56 *   module area.
     57 *
     58 * 3) KASAN_SHADOW_OFFSET:
     59 *   This value is used to map an address to the corresponding shadow
     60 *   address by the following formula:
     61 *
     62 *	shadow_addr = (address >> 3) + KASAN_SHADOW_OFFSET;
     63 *
     64 *  As you would expect, >> 3 is equal to dividing by 8, meaning each
     65 *  byte in the shadow memory covers 8 bytes of kernel memory, so one
     66 *  bit shadow memory per byte of kernel memory is used.
     67 *
     68 *  The KASAN_SHADOW_OFFSET is provided in a Kconfig option depending
     69 *  on the VMSPLIT layout of the system: the kernel and userspace can
     70 *  split up lowmem in different ways according to needs, so we calculate
     71 *  the shadow offset depending on this.
     72 */
     73
     74#define KASAN_SHADOW_SCALE_SHIFT	3
     75#define KASAN_SHADOW_OFFSET	_AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
     76#define KASAN_SHADOW_END	((UL(1) << (32 - KASAN_SHADOW_SCALE_SHIFT)) \
     77				 + KASAN_SHADOW_OFFSET)
     78#define KASAN_SHADOW_START      ((KASAN_SHADOW_END >> 3) + KASAN_SHADOW_OFFSET)
     79
     80#endif
     81#endif