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Kernel: Add convenient ways to map whole BIOS and EBDA into memory

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This patch adds a MappedROM abstraction to the Kernel VM subsystem.
It's basically the read-only byte buffer equivalent of a TypedMapping.

We use this in the ACPI and MP table parsers to scan for interesting
stuff in low memory instead of doing a bunch of address arithmetic.
This commit is contained in:
Andreas Kling 2020-05-22 12:55:23 +02:00
parent 6b5d2afd00
commit 84b7bc5e14
8 changed files with 169 additions and 47 deletions
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59
Kernel/Arch/PC/BIOS.cpp Normal file
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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
*/
#include <AK/StringView.h>
#include <Kernel/Arch/PC/BIOS.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/TypedMapping.h>
namespace Kernel {
MappedROM map_bios()
{
MappedROM mapping;
mapping.size = 128 * KB;
mapping.paddr = PhysicalAddress(0xe0000);
mapping.region = MM.allocate_kernel_region(mapping.paddr, PAGE_ROUND_UP(mapping.size), {}, Region::Access::Read);
return mapping;
}
MappedROM map_ebda()
{
auto ebda_segment_ptr = map_typed<u16>(PhysicalAddress(0x40e));
auto ebda_length_ptr = map_typed<u16>(PhysicalAddress(0x413));
PhysicalAddress ebda_paddr(*ebda_segment_ptr << 4);
size_t ebda_size = *ebda_length_ptr;
MappedROM mapping;
mapping.region = MM.allocate_kernel_region(ebda_paddr.page_base(), PAGE_ROUND_UP(ebda_size), {}, Region::Access::Read);
mapping.offset = ebda_paddr.offset_in_page();
mapping.size = ebda_size;
mapping.paddr = ebda_paddr;
return mapping;
}
}