bareflank-hypervisor/loader/include/alloc_and_copy_mk_code_aliases.h
Rian Quinn dcbe19368c Adds missing unit tests for the loader
This patch:
- Completes the unit tests for the loader
- Fixes issues with Clang Tidy
2021-10-15 08:07:34 -06:00

80 lines
3.5 KiB
C

/**
* @copyright
* Copyright (C) 2020 Assured Information Security, Inc.
*
* @copyright
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* @copyright
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* @copyright
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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*/
#ifndef ALLOC_AND_COPY_MK_CODE_ALIASES_H
#define ALLOC_AND_COPY_MK_CODE_ALIASES_H
#include <code_aliases_t.h>
#include <types.h>
#ifdef __cplusplus
extern "C"
{
#endif
/**
* <!-- description -->
* @brief The function's main purpose is allocate pages for all of the
* executable code that is currently linked into the kernel module, and
* copy this code into the newly allocated pages so that they can be
* mapped into the microkernel's page tables, creating an alias.
* The following diagram is what we are doing here:
*
* |-------> physical address (OS kernel)
* |
* virtual address <----|
* |
* |-------> physical address (microkernel)
*
* As you can see, the same virtual address for both the OS kernel and
* the microkernel point to two different physical addresses. The
* physical address for the microkernel is the alias, and we create
* the alias by copying the page located in the OS kenrel to the page
* located in the microkernel. This is done because we cannot actually
* get the physical address of the OS kernel, but we can access the
* contents of the page using the virtual address. So we copy the page
* to a page that we can get the physical address of and point the
* microkernel to that page instead. It should be noted that on Linux,
* if you do try to get the physical address of the code that we need
* to map into the microkernel, you will actually get what looks like
* a valid physical address, but be warned that the page it returns
* is actually garbage. You can only get the physical address of
* memory that is allocated using vmalloc(), which is why we need to
* create the aliases, as we need the physical address of the code so
* that we can map it into the microkernel's page tables.
*
* <!-- inputs/outputs -->
* @param pmut_a a pointer to a code_aliases_t that will store the
* resulting aliases.
* @return LOADER_SUCCESS on success, LOADER_FAILURE on failure.
*/
NODISCARD int64_t alloc_and_copy_mk_code_aliases(struct code_aliases_t *const pmut_a) NOEXCEPT;
#ifdef __cplusplus
}
#endif
#endif