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feat(gdt): add gdt kernel entries creation 

Signed-off-by: Julien CLEMENT <julien.clement@epita.fr>
This commit is contained in:
Julien CLEMENT 2021-07-13 22:31:01 +02:00
parent e862a4185b
commit a5ff8a6a92
3 changed files with 58 additions and 1 deletions
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53
k/gdt.c
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@ -4,10 +4,58 @@ static struct gdt gdt = { 0 };
static void create_kernel_ds()
{
struct gdt_entry *entry = gdt.entries + KERNEL_DS_INDEX;
uint32_t limit = 0xffff;
uint32_t base = 0x0;
entry->granularity = 1;
entry->db = 1;
entry->l = 0;
entry->available = 0;
entry->present = 1;
entry->desc_priv = 0;
entry->desc_type = 1;
entry->ex = 0;
entry->dc = 0;
entry->rw = 1;
entry->accessed = 0;
entry->limit_1 = limit & 0xffff;
entry->limit_2 = (limit >> 16) & 0xf;
entry->base_1 = base & 0xffff;
entry->base_2 = (base >> 16) & 0xff;
entry->base_3 = (base >> 24) & 0xff;
}
static void create_kernel_cs()
{
struct gdt_entry *entry = gdt.entries + KERNEL_CS_INDEX;
uint32_t limit = 0xffff;
uint32_t base = 0x0;
entry->granularity = 1;
entry->db = 1;
entry->l = 0;
entry->available = 0;
entry->present = 1;
entry->desc_priv = 0;
entry->desc_type = 1;
entry->ex = 1;
entry->dc = 0;
entry->rw = 1;
entry->accessed = 0;
entry->limit_1 = limit & 0xffff;
entry->limit_2 = (limit >> 16) & 0xf;
entry->base_1 = base & 0xffff;
entry->base_2 = (base >> 16) & 0xff;
entry->base_3 = (base >> 24) & 0xff;
}
static void create_gdt()
@ -62,13 +110,18 @@ static void load_cs()
static void reload_segment_selectors()
{
printf("Before load_ds\r\n");
load_ds();
load_cs();
}
void init_gdt()
{
printf("Before create_gdt\r\n");
create_gdt();
printf("Before load_gdt\r\n");
load_gdt();
printf("Before reload_segment_selectors\r\n");
reload_segment_selectors();
printf("All good\r\n");
}

5
k/gdt.h
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@ -14,7 +14,10 @@ struct gdt_entry
uint16_t limit_1 : 16;
uint16_t base_1 : 16;
uint8_t base_2 : 8;
uint8_t seg_type : 4;
uint8_t accessed : 1;
uint8_t rw : 1;
uint8_t dc : 1;
uint8_t ex : 1;
uint8_t desc_type : 1;
uint8_t desc_priv : 2;
uint8_t present : 1;

1
k/k.c
View File

@ -30,6 +30,7 @@
static void k_init(void)
{
init_serial();
init_gdt();
}
void k_main(unsigned long magic, multiboot_info_t *info)