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#include "lib/kstring.h"
#include <stdint.h>
#include "tss.h"
struct sys_seg_descriptor {
uint64_t limit0_15 : 16;
uint64_t base0_15 : 16;
uint64_t base16_23 : 8;
uint64_t type : 4;
uint64_t : 1;
uint64_t DPL : 2;
uint64_t present : 1;
uint64_t limit16_19 : 4;
uint64_t available : 1;
uint64_t : 1;
uint64_t : 1;
uint64_t gran : 1;
uint64_t base24_31 : 8;
uint64_t base32_63 : 32;
uint64_t : 32;
} __attribute__((packed));
struct tss {
uint64_t : 32;
uint64_t rsp0 : 64;
uint64_t rsp1 : 64;
uint64_t rsp2 : 64;
uint64_t : 64;
uint64_t ist1 : 64;
uint64_t ist2 : 64;
uint64_t ist3 : 64;
uint64_t ist4 : 64;
uint64_t ist5 : 64;
uint64_t ist6 : 64;
uint64_t ist7 : 64;
uint64_t : 64;
uint64_t : 16;
uint64_t iopb : 16;
} __attribute__((packed));
// tss entry
static volatile struct tss tss;
// gdt entries
extern volatile uint8_t GDT[];
static volatile struct sys_seg_descriptor *GDT_TSS;
// kernel stack pointer
extern char kern_stack_end[];
void tss_init(void)
{
uint64_t base = (uint64_t)&tss;
uint64_t limit = sizeof tss - 1;
// setup tss entry
memsetv(&tss, 0, sizeof(struct tss));
tss.rsp0 = (uint64_t)kern_stack_end;
// map tss into gdt
GDT_TSS = (volatile struct sys_seg_descriptor *)(GDT + 0x28);
memsetv(GDT_TSS, 0, sizeof(struct sys_seg_descriptor));
GDT_TSS->limit0_15 = limit & 0xFFFF;
GDT_TSS->base0_15 = base & 0xFFFF;
GDT_TSS->base16_23 = (base >> 16) & 0xFF;
GDT_TSS->type = 0x9;
GDT_TSS->DPL = 0;
GDT_TSS->present = 1;
GDT_TSS->limit16_19 = (limit >> 16) & 0xF;
GDT_TSS->available = 0;
GDT_TSS->gran = 0;
GDT_TSS->base24_31 = (base >> 24) & 0xFF;
GDT_TSS->base32_63 = (base >> 32) & 0xFFFFFFFF;
tss_flush();
}
void tss_set_stack(uint64_t stack)
{
tss.rsp0 = stack;
}
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