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The great 64-bit rewrite

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* We did loose tasking and only have a paging skeleton, but hey it took like 4 months so i'm happy that there's something :p
This commit is contained in:
Tom-on
2026-02-08 13:04:39 +01:00
parent d9471572b8
commit 50a1d6198e
42 changed files with 2206 additions and 1786 deletions
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kernel/src/gdt.c
+85 -33
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@@ -2,54 +2,106 @@
#include <string.h>
#include <gdt.h>
static struct gdt_entry gdt[GDT_ENTRIES];
static struct gdt_entries gdt;
static struct gdt_pointer gdtp;
static struct tss_pointer tss;
void gdt_reload(void) {
__asm__ volatile (
"cli\n"
"lgdt (%0)\n"
"movw $0x10, %%ax\n"
"movw %%ax, %%ds\n"
"movw %%ax, %%es\n"
"movw %%ax, %%fs\n"
"movw %%ax, %%gs\n"
"movw %%ax, %%ss\n"
"ljmp $0x08, $1f\n"
"1:"
:
: "m" (gdtp)
: "memory", "rax"
"lgdt %0\n"
"pushq %[kcs]\n"
"lea 1f(%%rip), %%rax\n"
"pushq %%rax\n"
"lretq\n"
"1:\n"
"mov %[kds], %%ax\n"
"mov %%ax, %%ds\n"
"mov %%ax, %%es\n"
"mov %%ax, %%fs\n"
"mov %%ax, %%gs\n"
"mov %%ax, %%ss\n"
:
: "m"(gdtp),
[kcs] "i"(GDT_KERNEL_CODE),
[kds] "i"(GDT_KERNEL_DATA)
: "rax", "memory"
);
}
void tss_reload(void) {
__asm__ volatile ("ltr %0" : : "rm"(GDT_TSS));
void tss_load(struct tss_pointer* tss) {
size_t addr = (size_t)tss;
gdt.tss.length = 104;
gdt.tss.base_low = (uint16_t)addr;
gdt.tss.base_mid = (uint8_t)(addr >> 16);
gdt.tss.access = 0x89;
gdt.tss.flags = 0;
gdt.tss.base_high = (uint8_t)(addr >> 24);
gdt.tss.base_upper32 = (uint32_t)(addr >> 32);
gdt.tss.__reserved = 0;
__asm__ volatile ("ltr %0" : : "rm"(GDT_TSS) : "memory");
}
void tss_esp0(uint32_t esp0) { tss.esp0 = esp0; }
int gdt_init(void) {
// Null descriptor
gdt.entries[0].limit = 0;
gdt.entries[0].base_low = 0;
gdt.entries[0].base_mid = 0;
gdt.entries[0].access = 0;
gdt.entries[0].flags = 0;
gdt.entries[0].base_high = 0;
// Kernel code
gdt.entries[1].limit = 0xFFFF;
gdt.entries[1].base_low = 0;
gdt.entries[1].base_mid = 0;
gdt.entries[1].access = 0x9A;
gdt.entries[1].flags = 0xAF;
gdt.entries[1].base_high = 0;
// Kernel data
gdt.entries[2].limit = 0xFFFF;
gdt.entries[2].base_low = 0;
gdt.entries[2].base_mid = 0;
gdt.entries[2].access = 0x92;
gdt.entries[2].flags = 0xCF;
gdt.entries[2].base_high = 0;
// User data
gdt.entries[3].limit = 0xFFFF;
gdt.entries[3].base_low = 0;
gdt.entries[3].base_mid = 0;
gdt.entries[3].access = 0xF2;
gdt.entries[3].flags = 0xCF;
gdt.entries[3].base_high = 0;
// User code
gdt.entries[4].limit = 0xFFFF;
gdt.entries[4].base_low = 0;
gdt.entries[4].base_mid = 0;
gdt.entries[4].access = 0xFA;
gdt.entries[4].flags = 0xAF;
gdt.entries[4].base_high = 0;
// Task State Segment (TSS)
gdt.tss.length = 104;
gdt.tss.base_low = 0;
gdt.tss.base_mid = 0;
gdt.tss.access = 0x89; //0b10001001;
gdt.tss.flags = 0;
gdt.tss.base_high = 0;
gdt.tss.base_upper32 = 0;
gdt.tss.__reserved = 0;
// GDT Pointer
gdtp.limit = sizeof(gdt) - 1;
gdtp.base = (uint32_t)&gdt;
// Setup TSS
memset(&tss, 0, sizeof(tss));
tss.ss0 = GDT_KERNEL_DATA;
tss.iopb = sizeof(struct tss_pointer);
// Load descriptors
gdt[0] = GDT_DESC(0, 0, 0, 0); // Null descriptor
gdt[1] = GDT_DESC(0xFFFFFFFF, 0, 0x9A, 0xC0); // Kernel code
gdt[2] = GDT_DESC(0xFFFFFFFF, 0, 0x92, 0xC0); // Kernel data
gdt[3] = GDT_DESC(0xFFFFFFFF, 0, 0xFA, 0xC0); // User code
gdt[4] = GDT_DESC(0xFFFFFFFF, 0, 0xF2, 0xC0); // User data
gdt[5] = GDT_DESC(sizeof(tss) - 1, (uint32_t)&tss, 0x89, 0);
gdtp.base = (uint64_t)&gdt;
gdt_reload();
tss_reload();
memset(&tss, 0, sizeof(tss));
tss_load(&tss);
debugf("[gdt] GDT loaded.\n");