trying x86_64 support

Makefile

@@ -1,4 +1,4 @@
-LD = i686-elf-ld
+LD = x86_64-elf-ld
 LFLAGS = -melf_i386 -nostdlib -O2 -T link.ld 
 
 all: prepare cpu kernel_code drivers libc userspace mem link iso

kernel/Makefile

@@ -1,6 +1,6 @@
 OBJS = kernel_main.o
 
-CC = i686-elf-gcc # cross-compiler
+CC = x86_64-elf-gcc # cross-compiler
 CFLAGS = -m32 -fno-stack-protector -ffreestanding -Wall -Wextra -Werror -g -c
 
 

kernel/cpu/Makefile

@@ -1,4 +1,4 @@
-OBJS =  main.asm.o ports.asm.o  \
+OBJS =  main.asm.o main64.asm.o ports.asm.o  \
 		gdt.asm.o idt.asm.o \
 		interrupts.asm.o header.asm.o
 

kernel/cpu/main.asm

@@ -5,23 +5,169 @@
 ;        Released under GPLv3           ;
 ;   https://github.com/ice-bit/vulcanos ;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-GLOBAL kernel_loader
-EXTERN kernel_main
+
+EXTERN long_mode_start
 [BITS 32] ; Ensure we are in protected mode
 
 section .text
 kernel_loader:
     mov esp, kernel_stack + KERNEL_STACK_SZ ; Define stack pointer
+    ; Now we need to switch to Long Mode(i.e., 64bit mode)
+    ; to do that, we first need to check if we actually are
+    ; being loaded by a multiboot compliant bootloader. Then,
+    ; we will execute CPUID instruction in order to obtain details
+    ; about out CPU(i.e., if the CPU supports long mode).
+    call check_multiboot
+    call check_cpuid
+    call check_long_mode
+
+    ; After that, we need to setup paging
+    call setup_page_tables
+    call enable_paging
+
+    ; We also need to load a GDT
+    lgdt[gdt64.pointer]
+    jmp gdt64.code_segment:long_mode_start
     push eax ; Set multiboot header register
-    call kernel_main ; Call kernel's main function
+
+
+check_multiboot:
+    ; To prove that we are being loaded by a multiboot 
+    ; bootloader, we can read the EAX register to see if 
+    ; it contains the magic number
+    cmp eax, 0xE85250D6
+    jne .multiboot_panic
+    ret
+
+.multiboot_panic:
+    ; We handle this error by showing a special code
+    mov al, "M"
+    jmp error ; Call print routine
+
+check_cpuid:
+    ; To check if CPUID is available we need to flip
+    ; ID bit of the flag register, if this is possibile
+    ; then CPUID instruction is available. In order to achieve
+    pushfd ; Push flag register into the stack
+    pop eax ; Pop the stack
+    mov ecx, eax ; Make a copy of the stack
+    xor eax, 1 << 21 ; Flip ID bit(21th) from the eax register
+    push eax
+    popfd ; Restore flag register into the stack
+    pushfd
+    pop eax
+    push ecx
+    popfd
+    cmp eax, ecx ; If values are the same, then CPUID is not available
+    je .cpuid_panic
+    ret ; Otherwise return
+
+.cpuid_panic:
+    mov al, "C"
+    jmp error ; Call print routine
+
+
+check_long_mode:
+    ; Check if CPU supports extended processor info
+    mov eax, 0x80000000 ; Store magic number
+    cpuid ; CPUID instruction takes EAX by default
+    ; CPUID will set EAX a value greater than the magic number 
+    ; if the processor supports extended processor info
+    cmp eax, 0x80000001 ; Magic number + 1
+    jb .long_mode_panic
+    ; Otherwise we can use extended processor info 
+    ; to check if long mode is available
+    mov eax, 0x80000001
+    cpuid
+    ; CPUID, with this magic number, will set LM bit(29th)
+    ; if and only if long mode is available
+    test edx, 1 << 29
+    jz .long_mode_panic
+    ret
+
+.long_mode_panic:
+    mov al, "L"
+    jmp error ; Call print routine
+
+
+setup_page_tables:
+    mov eax, page_table_l3
+    or eax, 0b11
+    mov [page_table_l4], eax
+
+    mov eax, page_table_l2
+    or eax, 0b11
+    mov [page_table_l3], eax
+
 .loop:
-    jmp .loop ; If the kernel returns, go into an endless loop
-              ; This will prevent the CPU to execure any non-kernel 
-              ; instructions.
+    mov eax, 0x200000 ; 2MiB
+    mul ecx
+    or eax, 0b10000011
+    mov [page_table_l2 + ecx * 8], eax
+
+    mov ecx, 0 ; Counter
+    inc ecx ; Increment counter
+    cmp ecx, 512 ; Check if whole table is being mapped
+    jne .loop ; if not, repeat
+    ret
+
+enable_paging:
+    ; Pass page table location to the cpu
+    mov eax, page_table_l4
+    mov cr3, eax
+    ; Enable PAE
+    mov eax, cr4
+    or eax, 1 << 5
+    mov cr4, eax;
+    ; Enable long mode
+    mov ecx, 0xC0000000
+    rdmsr
+    or eax, 1 << 8
+    wrmsr
+    ; Enable paging
+    mov eax, cr0
+    or eax, 1 << 31
+    mov cr0, eax
+    
+    ret
+
+error: ; Prints "ERR: X" where X stands ofr the given error code
+    ; This routine will just print the error code in video memory
+    ; Let's understand what those hex codes actually mean:
+    ; 0xB8000 is the begin of the VGA text buffer, each byte will 
+    ; contain one character. 0x4F is the color code; it means 
+    ; white text on read background. 0x52 is the ASCII code for
+    ; the letter 'R', while 0x45 stands for the letter 'E',
+    ; 0x3A stands for the symbol ':' and 0x20 is just a space.
+    ; Do note that addressing is in little endian ordering and 
+    ; that one space is begin overwritten by the ASCII byte.
+    ;                                 previous      NEW CONTENT
+    mov dword [0xB8000], 0x4F524F45 ; []            ER
+    mov dword [0xB8004], 0x4F3A4F52 ; [ER]          R:
+    mov dword [0xB8008], 0x4F204F20 ; [ERR:]        <space>
+    mov byte  [0xB800a], al ; Print the error code
+    hlt ; Halt the CPU
 
 KERNEL_STACK_SZ equ 4096 ; Stack size(4KiB)
 
 section .bss
-align 4
+align 4096
+page_table_l4:
+    resb 4096
+page_table_l3:
+    resb 4096
+page_table_l2:
+    resb 4096
 kernel_stack:
     resb KERNEL_STACK_SZ ; Reserver 4KiB for kernel's stack
+
+
+section .rodata
+gdt64:
+    dq 0 ; zero entry
+.code_segment: equ $ - gdt64
+    dq (1 << 4) | (1 << 44) | (1 << 47) | (1 << 53) ; Code segment
+    ; executable, descriptor,  present     64bit    flags
+.pointer:
+    dw $ - gdt64 - 1
+    dd gdt64

kernel/cpu/main64.asm

@@ -0,0 +1,27 @@
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;             vulcanOS Kernel           ;
+; Developed by Marco 'icebit' Cetica    ;
+;              (c) 2019-2021            ;
+;        Released under GPLv3           ;
+;   https://github.com/ice-bit/vulcanos ;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+GLOBAL long_mode_start
+GLOBAL kernel_loader
+EXTERN kernel_main
+section .text
+[BITS 64] ; Ensure we are in long mode
+
+long_mode_start:
+    xor ax, ax
+    mov ss, ax
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
+
+    ; Call the kernel's main method
+    call kernel_main ; Call kernel's main function
+    .loop:
+        jmp .loop ; If the kernel returns, go into an endless loop
+                ; This will prevent the CPU to execure any non-kernel 
+                ; instructions.

kernel/drivers/Makefile

@@ -1,7 +1,7 @@
 OBJS = tty.o gdt.o idt.o isr.o timer.o keyboard.o  \
 		fs.o cpuid.o
 
-CC = i686-elf-gcc # cross-compiler
+CC = x86_64-elf-gcc # cross-compiler
 CFLAGS = -m32 -fno-stack-protector -DDEFAULT_USER=root -DDEFAULT_HOSTNAME=vulcan -ffreestanding -Wall -Wextra -Werror -g -c
 
 

kernel/kernel_main.c

@@ -6,7 +6,7 @@
  * https://github.com/ice-bit/vulcanos   *
  *****************************************/
 #include "drivers/tty.h"
-#include "drivers/gdt.h"
+//#include "drivers/gdt.h"
 #include "drivers/idt.h"
 #include "drivers/timer.h"
 #include "drivers/keyboard.h"
@@ -41,9 +41,9 @@ void kernel_main(unsigned long magic, uint32_t addr) {
        
     printf("Loading kernel, wait please...");
     
-    gdt_setup(); // Setup Global Descriptor Table
-    PRTOK
-    printf("   - Loaded GDT");
+    // gdt_setup(); // Setup Global Descriptor Table
+    // PRTOK
+    // printf("   - Loaded GDT");
 
     idt_setup(); // Setup Interrupt Descriptor Table
     PRTOK

kernel/libc/Makefile

@@ -1,7 +1,7 @@
 OBJS = stdio.o string.o panic.o time.o
 VER := $(shell git rev-parse --short HEAD)
 
-CC = i686-elf-gcc # cross-compiler
+CC = x86_64-elf-gcc # cross-compiler
 CFLAGS = -DVULCAN_VERSION=$(VER) -m32 -fno-stack-protector -ffreestanding -Wall -Wextra -Werror -g -c
 
 

kernel/mem/Makefile

@@ -1,6 +1,6 @@
 OBJS = paging.o kheap.o ordered_array.o
 
-CC = i686-elf-gcc # cross-compiler
+CC = x86_64-elf-gcc # cross-compiler
 CFLAGS = -m32 -fno-stack-protector -ffreestanding -Wall -Wextra -Werror -g -c
 
 all:${OBJS}

kernel/userspace/Makefile

@@ -1,7 +1,7 @@
 OBJS = shell.o fetch.o
 VER := $(shell git rev-parse --short HEAD)
 
-CC = i686-elf-gcc # cross-compiler
+CC = x86_64-elf-gcc # cross-compiler
 CFLAGS = -DDEFAULT_USER=root -DDEFAULT_HOSTNAME=vulcan -DVULCAN_VERSION=$(VER) -m32 -fno-stack-protector -ffreestanding -Wall -Wextra -Werror -g -c 
 
 all:${OBJS}