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#include "gdt.h"
#include "kprintf.h"
#include "asm_inline.h"
#include "memops.h"
#define NULL_DESCRIPTOR 0
#define KERNEL_CODE 1
#define KERNEL_DATA 2
#define USER_CODE 3
#define USER_DATA 4
#define TASK_STATE_SEGMENT_LOW 5
#define TASK_STATE_SEGMENT_HIGH 6
__attribute__((aligned(0x08)))
uint64_t gdt[7];
gdt_load gdt_l;
tss tss_g;
// #define KDEBUG
extern void asm_reload_segments();
int init_gdt()
{
/*
create_descriptor(NULL_DESCRIPTOR, 0, 0, 0, 0);
create_descriptor(KERNEL_CODE, 0, 0xFFFF, 0x9A, 0xA);
create_descriptor(KERNEL_DATA, 0, 0xFFFF, 0x92, 0xC);
create_descriptor(USER_CODE, 0, 0xFFFF, 0xFA, 0xA);
create_descriptor(USER_DATA, 0, 0xFFFF, 0xF2, 0xC);
*/
gdt[NULL_DESCRIPTOR] = 0x0000000000000000;
/*
gdt[KERNEL_CODE] = 0x0020980000000000; // Code, DPL=0, R/X
gdt[KERNEL_DATA] = 0x0000920000000000; // Data, DPL=0, W
gdt[USER_CODE] = 0x0020F80000000000; // Code, DPL=3, R/X
gdt[USER_DATA] = 0x0000F20000000000; // Data, DPL=3, W
*/
code_segment kernel_code = {
.limit = 0xFFFF,
.base_low = 0x0,
.base_mid = 0x0,
.A = 0x0,
.R = 0x1,
.C = 0x0, // conforming, used for privilege changes, leave it for now
.one0 = 0x1,
.one1 = 0x1,
.DPL = 0x0, // 0 -> kernel code
.P = 0x1,
.limit_high = 0xF,
.AVL = 0x0,
.L = 0x1,
.D = 0x0,
.G = 0x1,
.base_high = 0x0
};
data_segment kernel_data = {
.limit = 0xFFFF,
.base_low = 0x0,
.base_mid = 0x0,
.A = 0x0,
.W = 0x1,
.E = 0x0,
.zero = 0,
.one = 1,
.DPL = 0x0,
.P = 0x1,
.limit_high = 0xF,
.AVL = 0x0,
.L = 0x1,
.D = 0x0,
.G = 0x1,
.base_high = 0x0
};
code_segment user_code = {
.limit = 0xFFFF,
.base_low = 0x0,
.base_mid = 0x0,
.A = 0x0,
.R = 0x1, // ?
.C = 0x0, // conforming, used for privilege changes, leave it for now
.one0 = 0x1,
.one1 = 0x1,
.DPL = 0x3, // 0 -> user code
.P = 0x1,
.limit_high = 0xF,
.AVL = 0x0,
.L = 0x1,
.D = 0x0,
.G = 0x1,
.base_high = 0x0
};
data_segment user_data = {
.limit = 0xFFFF,
.base_low = 0x0,
.base_mid = 0x0,
.A = 0x0,
.W = 0x1,
.E = 0x0,
.zero = 0,
.one = 1,
.DPL = 0x3,
.P = 0x1,
.limit_high = 0xF,
.AVL = 0x0,
.L = 0x1,
.D = 0x0,
.G = 0x1,
.base_high = 0x0
};
//uint64_t addr = (uint64_t)tss_a;
//tss_a[16] = 0x00680000;
tss_g.rsv0 = 0x0;
tss_g.rsp0 = rrsp(); // <- change with ring 0 stack pointer(who knows which one is it, need to allocate or reserve?)
tss_g.rsp1 = 0x0;
tss_g.rsp2 = 0x0;
tss_g.rsv1 = 0x0;
tss_g.ist2 = 0x0;
tss_g.ist3 = 0x0;
tss_g.ist4 = 0x0;
tss_g.ist5 = 0x0;
tss_g.ist6 = 0x0;
tss_g.ist7 = 0x0;
tss_g.rsv2 = 0x0;
tss_g.rsv3 = 0x0;
tss_g.io_base = sizeof(tss);
uint64_t tss_m;
kmemcpy(&tss_g, &tss_m, sizeof(uint64_t));
tss_segment gdt_tss = {
.limit_low = 0xFFFF,
.base_low = tss_m & 0xFFFFFF,
.type = 0x9, // <- available tss ? (busy is 0xB)
.zero0 = 0x0,
.DPL = 0x0,
.P = 0x1,
.limit_high = 0xF,
.AVL = 0x0,
.zero1 = 0x0,
.zero2 = 0x0,
.G = 0x1, // <- maybe?
.base_high = (tss_m >> 24) & 0xFFFFFFFFFF,
.rsv1 = 0x0,
.zero3 = 0x0,
.rsv2 = 0x0,
};
/*
kmemcpy(&kernel_code, &gdt[KERNEL_CODE], sizeof(uint64_t));
kmemcpy(&kernel_data, &gdt[KERNEL_DATA], sizeof(uint64_t));
kmemcpy(&user_code, &gdt[USER_CODE], sizeof(uint64_t));
kmemcpy(&user_data, &gdt[USER_DATA], sizeof(uint64_t));
*/
kmemcpy(&gdt_tss, &gdt[TASK_STATE_SEGMENT_LOW], 2*sizeof(uint64_t));
uint64_t kc = convert_code_segment(&kernel_code);
uint64_t kd = convert_data_segment(&kernel_data);
uint64_t uc = convert_code_segment(&user_code);
uint64_t ud = convert_data_segment(&user_data);
gdt[KERNEL_CODE] = kc;
// gdt[KERNEL_DATA] = kd;
gdt[KERNEL_DATA] = 0x0000920000000000; // maybe my code is wrong <- yes it is, no idea why, discovered, and can be safely hardcoded for 64bit
gdt[USER_CODE] = uc;
gdt[USER_DATA] = 0x0000920000000000;
// gdt[USER_DATA] = ud;
/*
gdt[TASK_STATE_SEGMENT_LOW] = (0x0067) | ((addr & 0xFFFFFF) << 16) |
(0x00E9LL << 40) | (((addr >> 24) & 0xFF) << 56);
gdt[TASK_STATE_SEGMENT_HIGH] = (addr >> 32);
*/
#ifdef KDEBUG
kprintf("gdt pointer: %p\n", gdt);
kprintf("KERNEL CODE: %lX\n", gdt[KERNEL_CODE]);
kprintf("KERNEL DATA: %lX\n", gdt[KERNEL_DATA]);
kprintf("USER CODE: %lX\n", gdt[USER_CODE]);
kprintf("USER DATA: %lX\n", gdt[USER_DATA]);
kprintf("FUNCTION\n");
kprintf("KERNEL CODE: %lX\n", kc);
kprintf("KERNEL DATA: %lX\n", kd);
kprintf("USER CODE: %lX\n", uc);
kprintf("USER DATA: %lX\n", ud);
#endif
gdt_l.size = 7 * sizeof(uint64_t) - 1;
gdt_l.ptr = (uint64_t)(gdt);
lgdt(&gdt_l);
asm_reload_segments();
// ltr(TASK_STATE_SEGMENT_LOW << 3);
create_system_segment_descriptor();
return 1;
}
uint64_t create_descriptor(uint32_t base, uint32_t limit, uint8_t access_byte, uint16_t flag)
{
// need to redo
uint64_t descriptor;
descriptor = limit & 0x000F0000;
descriptor |= (flag << 8) & 0x00F0FF00;
descriptor |= (base >> 16) & 0x000000FF;
descriptor |= base & 0xFF000000;
descriptor <<= 32;
descriptor |= base << 16;
descriptor |= limit & 0x0000FFFF;
return descriptor;
}
void create_system_segment_descriptor()
{
}
uint64_t convert_code_segment(code_segment* segment)
{
uint64_t s = 0x0;
s = segment->limit & 0xFFFF;
s |= (uint64_t)(segment->base_low & 0xFFFF) << 16;
s |= (uint64_t)(segment->base_mid & 0xFF) << 32;
s |= (uint64_t)(segment->A & 0x1) << 40;
s |= (uint64_t)(segment->R & 0x1) << 41;
s |= (uint64_t)(segment->C & 0x1) << 42;
s |= (uint64_t)(segment->one0 & 0x1) << 43;
s |= (uint64_t)(segment->one1 & 0x1) << 44;
s |= (uint64_t)(segment->DPL & 0x3) << 45;
s |= (uint64_t)(segment->P & 0x1) << 47;
s |= (uint64_t)(segment->limit_high & 0xF) << 48;
s |= (uint64_t)(segment->AVL & 0x1) << 52;
s |= (uint64_t)(segment->L & 0x1) << 53;
s |= (uint64_t)(segment->D & 0x1) << 54;
s |= (uint64_t)(segment->G & 0x1) << 55;
s |= (uint64_t)(segment->base_high) << 56;
return s;
}
uint64_t convert_data_segment(data_segment* segment)
{
uint64_t s = 0x0;
uint32_t* ss = (uint32_t*)&s;
s = segment->limit & 0xFFFF;
s |= (uint64_t)(segment->base_low & 0xFFFF) << 16;
s |= (uint64_t)(segment->base_mid & 0xFF) << 32;
s |= (uint64_t)(segment->A & 0x1) << 40;
s |= (uint64_t)(segment->W & 0x1) << 41;
s |= (uint64_t)(segment->E & 0x1) << 42;
s |= (uint64_t)(segment->one & 0x1) << 43;
s |= (uint64_t)(segment->zero & 0x1) << 44;
s |= (uint64_t)(segment->DPL & 0x3) << 45;
s |= (uint64_t)(segment->P & 0x1) << 47;
s |= (uint64_t)(segment->limit_high & 0xF) << 48;
s |= (uint64_t)(segment->AVL & 0x1) << 52;
s |= (uint64_t)(segment->L & 0x1) << 53;
s |= (uint64_t)(segment->D & 0x1) << 54;
s |= (uint64_t)(segment->G & 0x1) << 55;
s |= (uint64_t)(segment->base_high) << 56;
return s;
}
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