feat: setup paging and map kernel to higher half

Kernel is now at 0xC0100000, but still we use 4MiB pages, instruction like 'invlpg' which are invalid for cpu prior to 486, and we don't ensure multiboot structures are mapped. Still lot of work

kernel/Makefile

@@ -1,5 +1,6 @@
 KERNEL	= vmstupid
-SRCS	= boot/head.s boot/feat.s kernel.s gdt.s pic.s isr.s idt.s pmm.s paging.s \
+SRCS	= boot/head.s \
+			kernel.s gdt.s pic.s isr.s idt.s \
 			lib/log.s drivers/serial.s
 INCS	= sys/multiboot.inc \
 			sys/i386/cpuid.inc \

kernel/boot/feat.s

@@ -1,55 +0,0 @@
-	;; File: feat.s
-%include "machdep.inc"
-%include "sys/i386/registers.inc"
-%include "sys/i386/cpuid.inc"
-%include "sys/i386/mmu.inc"
-
-section multiboot.text
-
-extern machdep
-
-	;; Function: cpuid_detect
-	;; check if cpuid is avaible.
-	;;
-	;; ripped from <osdev wiki at https://wiki.osdev.org/CPUID#Checking_CPUID_availability>
-cpuid_detect:
-	pushfd
-	pushfd
-	xor dword [esp], EFLAGS_ID
-	popfd
-	pushfd
-	pop eax
-	xor eax, [esp]
-	popfd
-	and eax, EFLAGS_ID
-	ret
-
-	;; Function: feat_detect
-global feat_detect
-feat_detect:
-	push ebp
-	mov ebp, esp
-
-	call cpuid_detect
-	test eax, eax
-	jz .has_cpuid
-	jmp .end
-.has_cpuid:
-	mov byte [V2P(machdep) + machinfo.has_cpuid], 1
-	mov eax, CPUID_GETFEATURES
-	cpuid
-
-	;; test if PSE is available
-	mov eax, edx
-	and eax, CPUID_FEAT_EDX_PSE
-	jz .end
-	mov byte [V2P(machdep) + machinfo.has_pse], 1
-
-	;; test if PAE is available (we won't support PAE for now)
-	mov eax, edx
-	and eax, CPUID_FEAT_EDX_PAE
-	jz .end
-	mov byte [V2P(machdep) + machinfo.has_pae], 1
-.end:
-	leave
-	ret

kernel/boot/head.s

@@ -1,8 +1,11 @@
 	;; File: head.s
-
+	;;
+	;; About: CPU compatibility
+	;; /!\ Only work on *486+* for now.
+	;; - `invlpg` which is not part of 386 ISA.
+	;;
 [BITS 32]
 
-%include "machdep.inc"
 %include "sys/multiboot.inc"
 %include "sys/i386/registers.inc"
 %include "sys/i386/mmu.inc"
@@ -38,24 +41,35 @@ section .multiboot.text
 	;;
 global entry
 entry:
-	extern stack_top
-	mov esp, V2P(stack_top)
+	;; disable interrupt
+	cli
 
 	;; save boot params
 	mov edi, eax
 	mov esi, ebx
 
-	extern feat_detect
-	call feat_detect
-
 	;; setup 4MB paging
 	;; TODO: check if 4MB paging is available
 	mov eax, cr4
 	or eax, CR4_PSE
 	mov cr4, eax
 
+	cmp edi, MB_MAGIC
+	jne .skip_map_multiboot
+	;; check if multiboot struct is in first 4Mib
+	;; otherwith add entry in page dir
+	mov eax, 400000
+	cmp ebx, eax
+	jg .map_multiboot
+	jmp .skip_map_multiboot
+.map_multiboot:
+	;; TODO: for now let's assume data are bellow 4Mib 
+	jmp .end
+.skip_map_multiboot:
+	add esi, KERNBASE
+.end:
 	extern page_directory
-	mov eax, V2P(page_directory)
+	mov eax, V2P(boot_page_dir)
 	mov cr3, eax
 
 	;; enable paging
@@ -63,7 +77,34 @@ entry:
 	or eax, CR0_PG | CR0_PE | CR0_WP
 	mov cr0, eax
 
-	extern page_directory
-	mov eax, page_directory - KERNBASE
-	extern kernel_start
-	mov ebx, kernel_start
+	;; Jump to higher half
+	lea eax, entry_high
+	jmp eax						; near jump, indirect
+
+section .text
+
+entry_high:
+	mov dword [boot_page_dir], 0
+	invlpg [0]
+
+	extern stack_top
+	mov esp, stack_top
+	xor ebp, ebp
+
+	push edi
+	push esi
+	extern kmain
+	call kmain
+
+	cli
+hang:
+	hlt
+	jmp hang
+
+section .data
+align 0x1000
+boot_page_dir:
+	dd 0 | PDE_P | PDE_W | PDE_PS
+	times (P2PDE(KERNBASE) - 1) dd 0
+	dd 0 | PDE_P | PDE_W | PDE_PS
+	times 0x400 - (boot_page_dir - $$) dd 0

kernel/kernel.s

@@ -1,7 +1,7 @@
 ; File: kernel.s
 [BITS 32]
 
-%include "machdep.inc"
+%include "base.inc"
 
 section .bss
 align 16
@@ -17,14 +17,16 @@ kmain:
 	push ebp
 	mov ebp, esp
 
+	extern serial_init
+	call serial_init
+
+	LOG msg_hello_world
+	
 	leave
 	ret
 
-section .data
-global machdep
-machdep:
-	istruc machinfo
-		at machinfo.has_cpuid, db 0
-		at machinfo.has_pse, db 0
-		at machinfo.has_pae, db 0
-	iend
+section .rodata
+
+msg_hello_world db "StupidOS v", STUPID_VERSION, " (built with ", __NASM_VER__, " on ",  __DATE__, " ", __TIME__, ")", 0
+
+file db __FILE__, 0

kernel/linker.ld

@@ -7,7 +7,7 @@ SECTIONS
 	
 	kernel_start = .;
 
-	.multiboot : {
+	.multiboot ALIGN(0x1000): {
 		KEEP(*(.multiboot.data))
 		KEEP(*(.multiboot.text))
 	}

kernel/machdep.inc

@@ -1,5 +0,0 @@
-struc machinfo
-	.has_cpuid: resb 1
-	.has_pse: resb 1
-	.has_pae: resb 1	
-endstruc

kernel/sys/i386/mmu.inc

@@ -45,8 +45,12 @@
 %define PDE2P(addr) (addr << 22)
 %define P2PTE(addr) ((addr >> 12) & 0x3FF)
 
-	;; Defines: PDE
-	;; PTE_P    - Present
+	;; Defines: Page Directory Flags
+	;; PDE_P   - Present
+	;; PDE_W   - Writable
+	;; PDE_U   - User
+	;; PDE_PWT - Write-Through
+	;; PDE_PS  - 4MiB page
 PDE_P   equ 1 << 0
 PDE_W   equ 1 << 1
 PDE_U   equ 1 << 2
@@ -57,7 +61,7 @@ PDE_D   equ 1 << 6
 PDE_PS  equ 1 << 7
 PDE_G   equ 1 << 8
 
-	;; Defines: PTE
+	;; Defines: Page Table Flags
 	;; PTE_P   - Present
 	;; PTE_W   - Writable
 	;; PTE_U   - User

kernel/sys/multiboot.inc

@@ -105,11 +105,18 @@ struc mb_info
 endstruc
 
 ; Defines: flags
-; 
+;
 ; MB_INFO_MEM     - todo
-; MB_INFO_BOOTDEV - todo 
-MB_INFO_MEM equ 1 << 0
-MB_INFO_BOOTDEV equ 1 << 1
+; MB_INFO_BOOTDEV - todo
+MB_INFO_MEM             equ 1 << 0
+MB_INFO_BOOTDEV         equ 1 << 1
+MB_INFO_CMDLINE         equ 1 << 2
+MB_INFO_MODULES         equ 1 << 3
+MB_INFO_MMAP            equ 1 << 6
+MB_INFO_DRIVES          equ 1 << 7
+MB_INFO_BOOTLOADER_NAME equ 1 << 9
+MB_INFO_VBE             equ 1 << 11
+MB_INFO_FRAMEBUFFER     equ 1 << 12
 
 ; Structure: mb_mmap
 struc mb_mmap

lib/base/Makefile

@@ -3,4 +3,4 @@ SRCS = log.s
 INCS = base.inc
 
 include $(TOPDIR)/share/mk/stupid.lib.mk
-include $(TOPDIR)/share/mk/stupid.inc.mk
+#include $(TOPDIR)/share/mk/stupid.inc.mk