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Load a bare-bones TSS for CPU0

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This commit is contained in:
apio 2022-09-17 17:40:35 +02:00
parent 355ca6ea9f
commit 59ab8c016d
2 changed files with 59 additions and 5 deletions
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5
kernel/src/gdt/GDT.asm
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@ -14,3 +14,8 @@ load_gdt:
retfq
.reload_CS:
ret
global load_tr
load_tr:
mov rax, rdi
ltr ax
ret

59
kernel/src/gdt/GDT.cpp
View File

@ -1,7 +1,10 @@
#define MODULE "gdt"
#include "gdt/GDT.h"
#include "assert.h"
#include "log/Log.h"
#include "memory/KernelMemoryManager.h"
#include "std/string.h"
#include <stdint.h>
struct GDTR
@ -20,28 +23,74 @@ struct GDTEntry
uint8_t base2;
} __attribute__((packed));
struct HighGDTEntry
{
uint32_t base_high;
uint32_t reserved;
} __attribute__((packed));
struct TSS
{
uint32_t reserved0;
uint64_t rsp[3];
uint64_t reserved1;
uint64_t ist[7];
uint64_t reserved2;
uint16_t reserved3;
uint16_t iomap_base;
} __attribute__((packed));
struct InternalGDT
{
GDTEntry null;
GDTEntry kernel_code;
GDTEntry kernel_data;
GDTEntry user_null;
GDTEntry user_code;
GDTEntry user_data;
GDTEntry tss;
HighGDTEntry tss2;
} __attribute__((packed)) __attribute((aligned(0x1000)));
__attribute__((aligned(0x1000))) static InternalGDT internal_gdt = {
{0x0000, 0x0000, 0x00, 0x00, 0x00, 0x00}, {0xffff, 0x0000, 0x00, 0x9a, 0xaf, 0x00},
{0xffff, 0x0000, 0x00, 0x92, 0xcf, 0x00}, {0x0000, 0x0000, 0x00, 0x00, 0x00, 0x00},
{0xffff, 0x0000, 0x00, 0xfa, 0xaf, 0x00}, {0xffff, 0x0000, 0x00, 0xf2, 0xcf, 0x00}};
__attribute__((aligned(0x1000))) static InternalGDT internal_gdt = {{0x0000, 0x0000, 0x00, 0x00, 0x00, 0x00},
{0xffff, 0x0000, 0x00, 0x9a, 0xaf, 0x00},
{0xffff, 0x0000, 0x00, 0x92, 0xcf, 0x00},
{0xffff, 0x0000, 0x00, 0xfa, 0xaf, 0x00},
{0xffff, 0x0000, 0x00, 0xf2, 0xcf, 0x00},
{0x0000, 0x0000, 0x00, 0xe9, 0xcf, 0x00},
{0x00000000, 0x00000000}};
static TSS main_tss;
extern "C" void load_gdt(GDTR* gdtr);
extern "C" void load_tr(int segment);
static void set_base(GDTEntry* entry, uint32_t base)
{
entry->base0 = (base & 0xFFFF);
entry->base1 = (base >> 16) & 0xFF;
entry->base2 = (base >> 24) & 0xFF;
}
static void set_limit(GDTEntry* entry, uint32_t limit)
{
ASSERT(limit <= 0xFFFFF);
entry->limit0 = limit;
entry->limit1_flags = (entry->limit1_flags & 0xF0) | (limit & 0xF);
}
void GDT::load()
{
static GDTR gdtr;
gdtr.offset = (uint64_t)&internal_gdt;
gdtr.size = sizeof(InternalGDT);
memset(&main_tss, 0, sizeof(TSS));
main_tss.rsp[0] =
(uint64_t)KernelMemoryManager::get_pages(4) + (4096 * 4) - 8; // allocate 16KB for the syscall stack
set_base(&internal_gdt.tss, (uint64_t)&main_tss & 0xffffffff);
internal_gdt.tss2.base_high = (uint64_t)&main_tss >> 32;
set_limit(&internal_gdt.tss, sizeof(TSS) - 1);
kdbgln("Loading GDT at offset %lx, size %d", gdtr.offset, gdtr.size);
load_gdt(&gdtr);
kdbgln("Loading TR (GDT entry 0x28)");
load_tr(0x28);
}