RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-07-08 20:17:34 +00:00
Code Issues Activity Actions

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

Browse source 
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
Download patch file Download diff file Expand all files Collapse all files

37
Kernel/ACPI/MultiProcessorParser.cpp
View file

@ -27,6 +27,7 @@
#include <AK/StringView.h>
#include <Kernel/ACPI/MultiProcessorParser.h>
#include <Kernel/Arch/PC/BIOS.h>
#include <Kernel/Interrupts/IOAPIC.h>
#include <Kernel/StdLib.h>
#include <Kernel/VM/MemoryManager.h>
@ -115,42 +116,28 @@ void MultiProcessorParser::parse_configuration_table()
PhysicalAddress MultiProcessorParser::search_floating_pointer()
{
PhysicalAddress mp_floating_pointer;
auto region = MM.allocate_kernel_region(PhysicalAddress(0), PAGE_SIZE, "MultiProcessor Parser Floating Pointer Structure Finding", Region::Access::Read);
u16 ebda_seg = (u16) * ((uint16_t*)((region->vaddr().get() & PAGE_MASK) + 0x40e));
klog() << "MultiProcessor: Probing EBDA, Segment 0x" << String::format("%x", ebda_seg);
mp_floating_pointer = search_floating_pointer_in_ebda(ebda_seg);
auto mp_floating_pointer = search_floating_pointer_in_ebda();
if (!mp_floating_pointer.is_null())
return mp_floating_pointer;
return search_floating_pointer_in_bios_area();
}
PhysicalAddress MultiProcessorParser::search_floating_pointer_in_ebda(u16 ebda_segment)
PhysicalAddress MultiProcessorParser::search_floating_pointer_in_ebda()
{
auto floating_pointer_region = MM.allocate_kernel_region(PhysicalAddress(page_base_of((u32)(ebda_segment << 4))), PAGE_ROUND_UP(1024), "MultiProcessor Parser floating_pointer Finding #1", Region::Access::Read, false, true);
char* p_floating_pointer_str = (char*)(PhysicalAddress(ebda_segment << 4).as_ptr());
for (char* floating_pointer_str = (char*)floating_pointer_region->vaddr().offset(offset_in_page((u32)(ebda_segment << 4))).as_ptr(); floating_pointer_str < (char*)(floating_pointer_region->vaddr().offset(offset_in_page((u32)(ebda_segment << 4))).get() + 1024); floating_pointer_str += 16) {
#ifdef MULTIPROCESSOR_DEBUG
//dbg() << "MultiProcessor: Looking for floating pointer structure in EBDA @ V0x " << String::format("%x", floating_pointer_str) << ", P0x" << String::format("%x", p_floating_pointer_str);
#endif
if (!strncmp("_MP_", floating_pointer_str, strlen("_MP_")))
return PhysicalAddress((FlatPtr)p_floating_pointer_str);
p_floating_pointer_str += 16;
klog() << "MultiProcessor: Probing EBDA";
auto ebda = map_ebda();
for (auto* floating_pointer_str = ebda.base(); floating_pointer_str < ebda.end(); floating_pointer_str += 16) {
if (!strncmp("_MP_", (const char*)floating_pointer_str, strlen("_MP_")))
return ebda.paddr_of(floating_pointer_str);
}
return {};
}
PhysicalAddress MultiProcessorParser::search_floating_pointer_in_bios_area()
{
auto floating_pointer_region = MM.allocate_kernel_region(PhysicalAddress(page_base_of((u32)0xE0000)), PAGE_ROUND_UP(0xFFFFF - 0xE0000), "MultiProcessor Parser floating_pointer Finding #2", Region::Access::Read, false, true);
char* p_floating_pointer_str = (char*)(PhysicalAddress(0xE0000).as_ptr());
for (char* floating_pointer_str = (char*)floating_pointer_region->vaddr().offset(offset_in_page((u32)(0xE0000))).as_ptr(); floating_pointer_str < (char*)(floating_pointer_region->vaddr().offset(offset_in_page((u32)(0xE0000))).get() + (0xFFFFF - 0xE0000)); floating_pointer_str += 16) {
#ifdef MULTIPROCESSOR_DEBUG
//dbg() << "MultiProcessor: Looking for floating pointer structure in BIOS area @ V0x " << String::format("%x", floating_pointer_str) << ", P0x" << String::format("%x", p_floating_pointer_str);
#endif
if (!strncmp("_MP_", floating_pointer_str, strlen("_MP_")))
return PhysicalAddress((FlatPtr)p_floating_pointer_str);
p_floating_pointer_str += 16;
auto bios = map_bios();
for (auto* floating_pointer_str = bios.base(); floating_pointer_str < bios.end(); floating_pointer_str += 16) {
if (!strncmp("_MP_", (const char*)floating_pointer_str, strlen("_MP_")))
return bios.paddr_of(floating_pointer_str);
}
return {};
}