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Kernel: Move GDT to Processor

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Bananymous
2024-03-06 00:02:18 +02:00
parent 8670364f44
commit 58aca68726
6 changed files with 142 additions and 99 deletions
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112
kernel/arch/x86_64/GDT.cpp
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@@ -1,68 +1,35 @@
#include <BAN/Array.h>
#include <kernel/GDT.h>
#include <kernel/Debug.h>
#include <string.h>
namespace Kernel::GDT
namespace Kernel
{
struct TaskStateSegment
GDT* GDT::create()
{
uint32_t reserved1;
uint64_t rsp0;
uint64_t rsp1;
uint64_t rsp2;
uint64_t reserved2;
uint64_t ist1;
uint64_t ist2;
uint64_t ist3;
uint64_t ist4;
uint64_t ist5;
uint64_t ist6;
uint64_t ist7;
uint64_t reserved3;
uint16_t reserved4;
uint16_t iopb;
} __attribute__((packed));
auto* gdt = new GDT();
ASSERT(gdt);
union SegmentDescriptor
{
struct
{
uint16_t limit1;
uint16_t base1;
uint8_t base2;
uint8_t access;
uint8_t limit2 : 4;
uint8_t flags : 4;
uint8_t base3;
} __attribute__((packed));
gdt->write_entry(0x00, 0x00000000, 0x00000, 0x00, 0x0); // null
gdt->write_entry(0x08, 0x00000000, 0xFFFFF, 0x9A, 0xA); // kernel code
gdt->write_entry(0x10, 0x00000000, 0xFFFFF, 0x92, 0xC); // kernel data
gdt->write_entry(0x18, 0x00000000, 0xFFFFF, 0xFA, 0xA); // user code
gdt->write_entry(0x20, 0x00000000, 0xFFFFF, 0xF2, 0xC); // user data
gdt->write_tss();
struct
{
uint32_t low;
uint32_t high;
} __attribute__((packed));
gdt->flush_gdt();
gdt->flush_tss();
} __attribute__((packed));
return gdt;
}
struct GDTR
{
uint16_t size;
uint64_t address;
} __attribute__((packed));
static constexpr uint16_t s_tss_offset = 0x28;
static TaskStateSegment s_tss;
static BAN::Array<SegmentDescriptor, 7> s_gdt; // null, kernel code, kernel data, user code, user data, tss low, tss high
static GDTR s_gdtr;
static void write_entry(uint8_t offset, uint32_t base, uint32_t limit, uint8_t access, uint8_t flags)
void GDT::write_entry(uint8_t offset, uint32_t base, uint32_t limit, uint8_t access, uint8_t flags)
{
ASSERT(offset % sizeof(SegmentDescriptor) == 0);
uint8_t idx = offset / sizeof(SegmentDescriptor);
SegmentDescriptor& desc = s_gdt[offset / sizeof(SegmentDescriptor)];
auto& desc = m_gdt[idx];
desc.base1 = (base >> 0) & 0xFFFF;
desc.base2 = (base >> 16) & 0xFF;
desc.base3 = (base >> 24) & 0xFF;
@@ -75,49 +42,18 @@ namespace Kernel::GDT
desc.flags = flags & 0x0F;
}
static void write_tss()
void GDT::write_tss()
{
memset(&s_tss, 0x00, sizeof(TaskStateSegment));
s_tss.iopb = sizeof(TaskStateSegment);
memset(&m_tss, 0x00, sizeof(TaskStateSegment));
m_tss.iopb = sizeof(TaskStateSegment);
uint64_t base = (uint64_t)&s_tss;
uint64_t base = reinterpret_cast<uint64_t>(&m_tss);
write_entry(s_tss_offset, (uint32_t)base, sizeof(TaskStateSegment), 0x89, 0x0);
write_entry(0x28, (uint32_t)base, sizeof(TaskStateSegment), 0x89, 0x0);
SegmentDescriptor& desc = s_gdt[s_tss_offset / sizeof(SegmentDescriptor) + 1];
auto& desc = m_gdt[0x30 / sizeof(SegmentDescriptor)];
desc.low = base >> 32;
desc.high = 0;
}
void set_tss_stack(uintptr_t rsp)
{
s_tss.rsp0 = rsp;
}
static void flush_gdt()
{
asm volatile("lgdt %0" :: "m"(s_gdtr));
}
static void flush_tss()
{
asm volatile("ltr %0" :: "m"(s_tss_offset));
}
void initialize()
{
s_gdtr.address = (uint64_t)&s_gdt;
s_gdtr.size = s_gdt.size() * sizeof(SegmentDescriptor) - 1;
write_entry(0x00, 0x00000000, 0x00000, 0x00, 0x0); // null
write_entry(0x08, 0x00000000, 0xFFFFF, 0x9A, 0xA); // kernel code
write_entry(0x10, 0x00000000, 0xFFFFF, 0x92, 0xC); // kernel data
write_entry(0x18, 0x00000000, 0xFFFFF, 0xFA, 0xA); // user code
write_entry(0x20, 0x00000000, 0xFFFFF, 0xF2, 0xC); // user data
write_tss();
flush_gdt();
flush_tss();
}
}