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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/include/gdt.h
+43 -47
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@@ -8,7 +8,7 @@
#define DPL_USER 3
/*
* Segment selector explanation (why kcode is 0x08?)
* Segment selector explanation (why is kcode 0x08?)
*
* Each segment selector must be 16 bits. These bits
* have the following layout: (example is 0x08)
@@ -17,7 +17,7 @@
* | '--- Table indicator
* '------ Index in table
*
* Bits 0-1 are the privilege level. x86 has four,
* Bits 0-1 are the privilege level. x86(_64) has four,
* where 00 is the highest and 11 is the lowest. Only
* these two are widely used. 00 being kernel space &
* 11 being userspace. Bit 3 is the table indicator.
@@ -30,37 +30,23 @@
* s 0 for the GDT and the index is one, because it
* is the second entry in our GDT (after null desc.)
*/
#define SEGMENT_SEL(_idx, _tab, _dpl) (\
(((_dpl) ) & 3) | \
(((_tab) << 2) & 4) | \
(((_idx) << 3) ) \
)
/*
* Entries:
* 0 Null desc.
* 1 Kernel code desc.
* 2 Kernel data desc.
* 3 User code desc.
* 4 User data desc.
* 3 User data desc.
* 4 User code desc.
* 5 Task State Segment
*/
#define GDT_ENTRIES 6
#define GDT_NULL SEGMENT_SEL(0, 0, 0)
#define GDT_KERNEL_CODE SEGMENT_SEL(1, 0, DPL_KERNEL)
#define GDT_KERNEL_DATA SEGMENT_SEL(2, 0, DPL_KERNEL)
#define GDT_USER_CODE SEGMENT_SEL(3, 0, DPL_USER)
#define GDT_USER_DATA SEGMENT_SEL(4, 0, DPL_USER)
#define GDT_TSS SEGMENT_SEL(5, 0, DPL_KERNEL)
#define GDT_DESC(_lim, _base, _access, _flags) (struct gdt_entry) { \
.base_low = (_base) & 0xFFFF, \
.base_mid = ((_base) >> 16) & 0xFF, \
.base_high = ((_base) >> 24) & 0xFF, \
.limit = (_lim) & 0xFFFF, \
.flags = ((_flags) & 0xF0) | (((_lim) >> 16) & 0x0F), \
.access = (_access) \
}
#define GDT_ENTRIES 7
#define GDT_NULL 0x00
#define GDT_KERNEL_CODE 0x08
#define GDT_KERNEL_DATA 0x10
#define GDT_USER_DATA 0x18
#define GDT_USER_CODE 0x20
#define GDT_TSS 0x28
/*
* GDT descriptor/entry explanation
@@ -95,34 +81,44 @@ struct gdt_entry {
struct gdt_pointer {
uint16_t limit;
uint32_t base;
uint64_t base;
} __packed;
struct tss_entry {
uint16_t length;
uint16_t base_low;
uint8_t base_mid;
uint8_t access;
uint8_t flags;
uint8_t base_high;
uint32_t base_upper32;
uint32_t __reserved;
} __packed;
struct tss_pointer {
uint16_t prev_task, __reserved0;
uint32_t esp0;
uint16_t ss0, __reserved1;
uint32_t esp1;
uint16_t ss1, __reserved2;
uint32_t esp2;
uint16_t ss2, __reserved3;
uint32_t cr3;
uint32_t eip;
uint32_t eflags;
uint32_t eax, ecx, edx, ebx, esp, ebp, esi, edi;
uint16_t es, __reserved4;
uint16_t cs, __reserved5;
uint16_t ss, __reserved6;
uint16_t ds, __reserved7;
uint16_t fs, __reserved8;
uint16_t gs, __reserved9;
uint16_t ldtr;
uint32_t __reserved10;
uint32_t __reserved0;
uint64_t rsp0;
uint64_t rsp1;
uint64_t rsp2;
uint64_t __reserved1;
uint64_t ist1;
uint64_t ist2;
uint64_t ist3;
uint64_t ist4;
uint64_t ist5;
uint64_t ist6;
uint64_t ist7;
uint64_t __reserved2;
uint16_t __reserved3;
uint16_t iopb;
uint32_t ssp;
} __packed;
void tss_esp0(uint32_t esp0);
struct gdt_entries {
// GDT_ENTRIES - 2 to leave space for TSS
struct gdt_entry entries[GDT_ENTRIES - 2];
struct tss_entry tss;
} __packed;
int gdt_init(void);
#endif