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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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35
Kernel/ACPI/Parser.cpp
View file

@ -27,11 +27,12 @@
#include <AK/StringView.h>
#include <Kernel/ACPI/Parser.h>
#include <Kernel/Arch/PC/BIOS.h>
#include <Kernel/IO.h>
#include <Kernel/PCI/Access.h>
#include <Kernel/StdLib.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/TypedMapping.h>
#include <Kernel/IO.h>
#include <Kernel/StdLib.h>
namespace Kernel {
namespace ACPI {
@ -321,32 +322,25 @@ Parser::Parser(PhysicalAddress rsdp)
locate_static_data();
}
static PhysicalAddress find_rsdp_in_ebda(u16 ebda_segment)
static PhysicalAddress find_rsdp_in_ebda()
{
auto rsdp_region = MM.allocate_kernel_region(PhysicalAddress(page_base_of((u32)(ebda_segment << 4))), PAGE_ROUND_UP(1024), "ACPI Static Parser RSDP Finding #1", Region::Access::Read, false, true);
char* p_rsdp_str = (char*)(PhysicalAddress(ebda_segment << 4).as_ptr());
for (char* rsdp_str = (char*)rsdp_region->vaddr().offset(offset_in_page((u32)(ebda_segment << 4))).as_ptr(); rsdp_str < (char*)(rsdp_region->vaddr().offset(offset_in_page((u32)(ebda_segment << 4))).get() + 1024); rsdp_str += 16) {
auto ebda = map_ebda();
for (auto* rsdp_str = ebda.base(); rsdp_str < ebda.end(); rsdp_str += 16) {
#ifdef ACPI_DEBUG
dbg() << "ACPI: Looking for RSDP in EBDA @ V " << (void*)rsdp_str << ", P " << (void*)p_rsdp_str;
#endif
if (!strncmp("RSD PTR ", rsdp_str, strlen("RSD PTR ")))
return PhysicalAddress((FlatPtr)p_rsdp_str);
p_rsdp_str += 16;
if (!strncmp("RSD PTR ", (const char*)rsdp_str, strlen("RSD PTR ")))
return ebda.paddr_of(rsdp_str);
}
return {};
}
static PhysicalAddress find_rsdp_in_bios_area()
{
auto rsdp_region = MM.allocate_kernel_region(PhysicalAddress(0xE0000), PAGE_ROUND_UP(0xFFFFF - 0xE0000), "ACPI Static Parser RSDP Finding #2", Region::Access::Read, false, true);
char* p_rsdp_str = (char*)(PhysicalAddress(0xE0000).as_ptr());
for (char* rsdp_str = (char*)rsdp_region->vaddr().offset(offset_in_page((u32)(0xE0000))).as_ptr(); rsdp_str < (char*)(rsdp_region->vaddr().offset(offset_in_page((u32)(0xE0000))).get() + (0xFFFFF - 0xE0000)); rsdp_str += 16) {
#ifdef ACPI_DEBUG
dbg() << "ACPI: Looking for RSDP in BIOS ROM area @ V " << (void*)rsdp_str << ", P " << (void*)p_rsdp_str;
#endif
if (!strncmp("RSD PTR ", rsdp_str, strlen("RSD PTR ")))
return PhysicalAddress((FlatPtr)p_rsdp_str);
p_rsdp_str += 16;
auto bios = map_bios();
for (auto* rsdp_str = bios.base(); rsdp_str < bios.end(); rsdp_str += 16) {
if (!strncmp("RSD PTR ", (const char*)rsdp_str, strlen("RSD PTR ")))
return bios.paddr_of(rsdp_str);
}
return {};
}
@ -364,9 +358,8 @@ static bool validate_table(const Structures::SDTHeader& v_header, size_t length)
PhysicalAddress StaticParsing::find_rsdp()
{
auto ebda_seg_ptr = map_typed<u16>(PhysicalAddress(0x40e));
klog() << "ACPI: Probing EBDA, Segment 0x" << String::format("%x", *ebda_seg_ptr);
auto rsdp = find_rsdp_in_ebda(*ebda_seg_ptr);
klog() << "ACPI: Probing EBDA";
auto rsdp = find_rsdp_in_ebda();
if (!rsdp.is_null())
return rsdp;
return find_rsdp_in_bios_area();