From eaadde5453e33af6826bb03488991aab0297d3dd Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sun, 31 May 2020 20:26:40 +0200
Subject: OMG

---
 src/kernel/boot.asm            | 49 ++++++---------------------------
 src/kernel/events/event.c      |  5 +---
 src/kernel/fs/elf.c            |  5 ++--
 src/kernel/io/io.c             |  2 +-
 src/kernel/io/io.h             |  2 +-
 src/kernel/kernel.c            |  7 +++--
 src/kernel/lib/memory.c        |  1 -
 src/kernel/lib/stdio/vprintf.c |  2 +-
 src/kernel/linker.ld           | 20 ++++++--------
 src/kernel/memory/alloc.c      |  3 +-
 src/kernel/memory/paging.c     | 62 ++++++++++++++----------------------------
 src/kernel/memory/paging.h     |  4 +--
 src/kernel/multiboot.c         |  2 +-
 src/kernel/system.h            |  5 ++++
 src/kernel/tasks/process.c     |  8 +-----
 15 files changed, 56 insertions(+), 121 deletions(-)

diff --git a/src/kernel/boot.asm b/src/kernel/boot.asm
index 6aa5c1a..1e8d3ee 100644
--- a/src/kernel/boot.asm
+++ b/src/kernel/boot.asm
@@ -1,28 +1,17 @@
 bits 32
 
-; Some variables
-kernel_virt_base equ 0xC0000000
-kernel_page_number equ (kernel_virt_base >> 22)
 kernel_stack equ 0x4000
-
-section .data
-	align 0x1000
-
-	boot_page_dir:
-		dd 0x00000083
-		times (kernel_page_number - 1) dd 0
-		dd 0x00000083
-		times (1024 - kernel_page_number - 1) dd 0
+multiboot_magic equ 0xe85250d6
 
 section .text
 	align 4
 
 	multiboot:
 	header_start:
-		dd 0xe85250d6
+		dd multiboot_magic
 		dd 0
 		dd header_end - header_start
-		dd 0x100000000 - (0xe85250d6 + 0 + (header_end - header_start))
+		dd 0x100000000 - (multiboot_magic + 0 + (header_end - header_start))
 
 		; Information tag
 		align 8
@@ -34,12 +23,6 @@ section .text
 		dd 6 ; mmap
 		dd 13 ; smbios
 
-		; Page-align tag
-		align 8
-		dw 6
-		dw 0
-		dd 8
-
 		; Empty tag
 		align 8
 		dw 0
@@ -50,33 +33,17 @@ section .text
 	global boot
 	extern kernel_main
 	boot:
-		mov ecx, (boot_page_dir - kernel_virt_base)
-		mov cr3, ecx
-
-		mov ecx, cr4
-		or ecx, 0x00000010
-		mov cr4, ecx
-		
-		mov ecx, cr0
-		or ecx, 0x80000000
-		mov cr0, ecx
-
-		lea ecx, [higher_half]
-		jmp ecx
-
-	higher_half:
-		mov dword [boot_page_dir], 0
-		invlpg [0]
-		
-		mov esp, stack + kernel_stack
+		mov esp, stack_top
 		push esp
 		push ebx
 		push eax
 		cli
 		call kernel_main
 		hlt
+		jmp $
 
 section .bss
 	align 32
-	stack:
-		resb kernel_stack
\ No newline at end of file
+	stack_bottom:
+		resb kernel_stack
+	stack_top:
\ No newline at end of file
diff --git a/src/kernel/events/event.c b/src/kernel/events/event.c
index d479ab7..a50e0c7 100644
--- a/src/kernel/events/event.c
+++ b/src/kernel/events/event.c
@@ -18,10 +18,7 @@ u32 event_map(u32 id, u8 *function)
 
 u32 event_trigger(u32 id, u8 *data)
 {
-	if (id >= sizeof(event_map) / sizeof(*event_map)) {
-		panic("Unknown event id!");
-		return -1;
-	}
+	assert(id < sizeof(event_map) / sizeof(*event_map));
 
 	event_func location = (event_func)event_table[id];
 	if (!location) {
diff --git a/src/kernel/fs/elf.c b/src/kernel/fs/elf.c
index 2dddc0e..46a4876 100644
--- a/src/kernel/fs/elf.c
+++ b/src/kernel/fs/elf.c
@@ -30,7 +30,7 @@ struct process *elf_load(char *path)
 	if (current_proc)
 		prev_dir = current_proc->cr3;
 	else
-		prev_dir = current_page_directory;
+		prev_dir = page_directory;
 
 	u8 *file = read_file(path);
 	if (!file) {
@@ -73,8 +73,7 @@ struct process *elf_load(char *path)
 			       ((void *)((u32)file) + program_header->offset),
 			       program_header->filesz);
 			warn("3");
-			if (program_header->filesz > PAGE_SIZE)
-				panic("ELF binary section too large");
+			assert(program_header->filesz <= PAGE_SIZE);
 			break;
 		}
 		default:
diff --git a/src/kernel/io/io.c b/src/kernel/io/io.c
index fd7cd46..801a2fe 100644
--- a/src/kernel/io/io.c
+++ b/src/kernel/io/io.c
@@ -74,7 +74,7 @@ void outl(u16 port, u32 data)
 	asm volatile("outl %0, %1" ::"a"(data), "Nd"(port));
 }
 
-void init_serial()
+void serial_install()
 {
 	outb(0x3f8 + 1, 0x00);
 	outb(0x3f8 + 3, 0x80);
diff --git a/src/kernel/io/io.h b/src/kernel/io/io.h
index 2d078f1..b5573cc 100644
--- a/src/kernel/io/io.h
+++ b/src/kernel/io/io.h
@@ -54,7 +54,7 @@ void outl(u16 port, u32 data);
 /**
  * Initialize the serial conenction
  */
-void init_serial();
+void serial_install();
 
 /**
  * Write a single char to the serial port (QEMU logging)
diff --git a/src/kernel/kernel.c b/src/kernel/kernel.c
index bd22dfc..48525d9 100644
--- a/src/kernel/kernel.c
+++ b/src/kernel/kernel.c
@@ -40,14 +40,15 @@ void kernel_main(u32 magic, u32 addr, u32 esp)
 	info("Installing basic features of Melvix...");
 
 	// Install features
+	bss_clean();
 	gdt_install();
-	init_serial();
+	serial_install();
 	idt_install();
 	isrs_install();
 	irq_install();
 
-	paging_install(multiboot_address);
-	multiboot_parse(multiboot_address);
+	paging_install();
+	multiboot_parse();
 
 	// Install drivers
 	timer_install();
diff --git a/src/kernel/lib/memory.c b/src/kernel/lib/memory.c
index 40f6a1f..75f7870 100644
--- a/src/kernel/lib/memory.c
+++ b/src/kernel/lib/memory.c
@@ -122,7 +122,6 @@ int memory_init()
 
 void bss_clean()
 {
-	extern u8 bss_start, kernel_end;
 	u32 start = &bss_start;
 	u32 end = &kernel_end;
 	log("0x%x: 0x%x", start, end - start);
diff --git a/src/kernel/lib/stdio/vprintf.c b/src/kernel/lib/stdio/vprintf.c
index 3c4ecac..5405309 100644
--- a/src/kernel/lib/stdio/vprintf.c
+++ b/src/kernel/lib/stdio/vprintf.c
@@ -1,6 +1,6 @@
+#include <lib/lib.h>
 #include <lib/stdio.h>
 #include <lib/stdlib.h>
-#include <lib/lib.h>
 #include <stdint.h>
 
 // TODO: Use global formatting function
diff --git a/src/kernel/linker.ld b/src/kernel/linker.ld
index b7bde1d..a55b13f 100644
--- a/src/kernel/linker.ld
+++ b/src/kernel/linker.ld
@@ -1,32 +1,28 @@
 ENTRY(boot)
 
-phys = 0x100000;
-offset = 0xC0000000;
-virt = offset + phys;
-
 SECTIONS
 {
-	. = virt;
+	. = 1M;
 
-	.text : AT (ADDR (.text) - offset)
+	.text BLOCK(4K) : ALIGN(4K)
 	{
+		text_start = .;
 		*(.text)
 		*(.rodata)
-		. = ALIGN(0x1000);
 	}
 
-	.data : AT (ADDR (.data) - offset)
+	.data BLOCK(4K) : ALIGN(4K)
 	{
+		data_start = .;
 		*(.data)
-		. = ALIGN(0x1000);
 	}
 
-	.bss : AT (ADDR (.bss) - offset)
+	.bss BLOCK(4K) : ALIGN(4K)
 	{
+		bss_start = .;
 		*(.COMMON)
 		*(.bss)
-		. = ALIGN(0x1000);
 	}
 
-	KERNEL_END = .;
+	kernel_end = .;
 }
\ No newline at end of file
diff --git a/src/kernel/memory/alloc.c b/src/kernel/memory/alloc.c
index 904be3a..d1d8b47 100644
--- a/src/kernel/memory/alloc.c
+++ b/src/kernel/memory/alloc.c
@@ -162,8 +162,7 @@ static struct liballoc_major *allocate_new_page(u32 size)
 
 void *malloc(u32 req_size)
 {
-	if (!paging_enabled)
-		warn("Mallocing while paging is disabled!");
+	assert(paging_enabled);
 
 	int started_bet = 0;
 	u64 best_size = 0;
diff --git a/src/kernel/memory/paging.c b/src/kernel/memory/paging.c
index fd5ae3b..432b51c 100644
--- a/src/kernel/memory/paging.c
+++ b/src/kernel/memory/paging.c
@@ -4,55 +4,34 @@
 #include <stdint.h>
 #include <system.h>
 
-u32 **current_page_directory;
-u32 kernel_page_directory[PAGE_COUNT] __attribute__((aligned(PAGE_ALIGN)));
-u32 kernel_page_tables[PAGE_COUNT][PAGE_COUNT] __attribute__((aligned(PAGE_ALIGN)));
-u32 *temp_dir[PAGE_COUNT] __attribute__((aligned(PAGE_ALIGN)));
+u32 page_directory[1024] __attribute__((aligned(4096)));
+u32 page_tables[1024][1024] __attribute__((aligned(4096)));
 
-void paging_init(u32 **dir)
+void paging_init()
 {
 	for (u32 i = 0; i < PAGE_COUNT; i++) {
 		for (u32 j = 0; j < PAGE_COUNT; j++) {
-			dir[i][j] = ((j * PAGE_ALIGN) + (i * PAGE_SIZE)) | PT_RW | PT_USER;
+			page_tables[i][j] = ((j * PAGE_ALIGN) + (i * PAGE_SIZE)) | PT_RW | PT_USER;
 		}
 	}
 
 	for (u32 i = 0; i < PAGE_COUNT; i++) {
-		dir[i] = ((u32)dir[i]) | PD_RW | PD_PRESENT | PD_USER;
+		page_directory[i] = (u32)page_tables[i] | PD_RW | PD_PRESENT | PD_USER;
 	}
 }
 
-void paging_kernel_init(u32 *dir)
-{
-	for (u32 i = 0; i < PAGE_COUNT; i++) {
-		for (u32 j = 0; j < PAGE_COUNT; j++) {
-			kernel_page_tables[i][j] = ((j * PAGE_ALIGN) + (i * PAGE_SIZE)) | PT_RW;
-		}
-	}
-
-	for (u32 i = 0; i < PAGE_COUNT; i++) {
-		kernel_page_directory[i] = ((u32)kernel_page_tables[i]) | PD_RW | PD_PRESENT;
-	}
-
-	current_page_directory = temp_dir;
-	for (int i = 0; i < PAGE_COUNT; i++) {
-		current_page_directory[i] = kernel_page_tables[i];
-		for (int j = 0; j < PAGE_COUNT; j++) {
-			current_page_directory[i][j] = kernel_page_tables[i][j];
-		}
-	}
-}
-
-extern void KERNEL_END();
 void paging_install()
 {
-	paging_switch_directory((u32 **)kernel_page_directory);
-	paging_kernel_init(kernel_page_directory);
+	paging_init();
 
 	if (!memory_init())
 		paging_set_present(0, memory_get_all() >> 3);
-	paging_set_used(0, ((u32)KERNEL_END >> 12) + 1);
+	paging_set_used(0, ((u32)&kernel_end >> 12) + 1);
 
+	u32 cr4;
+	asm volatile("mov %%cr4, %0" : "=r"(cr4));
+	cr4 &= 0xffffffef;
+	asm volatile("mov %0, %%cr4" ::"r"(cr4));
 	paging_enable();
 	log("Installed paging");
 
@@ -99,6 +78,7 @@ void paging_disable()
 
 void paging_enable()
 {
+	asm("mov %0, %%cr3" ::"r"(page_directory));
 	u32 cr0;
 	asm("mov %%cr0, %0" : "=r"(cr0));
 	cr0 |= 0x80000000;
@@ -108,8 +88,7 @@ void paging_enable()
 
 void paging_switch_directory(u32 **dir)
 {
-	current_page_directory = dir;
-	asm("mov %0, %%cr3" ::"r"(current_page_directory));
+	asm("mov %0, %%cr3" ::"r"(dir));
 }
 
 void invlpg(u32 addr)
@@ -121,7 +100,7 @@ void paging_map(u32 phy, u32 virt, u16 flags)
 {
 	u32 pdi = virt >> 22;
 	u32 pti = virt >> 12 & 0x03FF;
-	current_page_directory[pdi][pti] = phy | flags;
+	page_tables[pdi][pti] = phy | flags;
 	invlpg(virt);
 }
 
@@ -129,21 +108,21 @@ u32 paging_get_phys(u32 virt)
 {
 	u32 pdi = virt >> 22;
 	u32 pti = (virt >> 12) & 0x03FF;
-	return current_page_directory[pdi][pti] & 0xFFFFF000;
+	return page_tables[pdi][pti] & 0xFFFFF000;
 }
 
 u16 paging_get_flags(u32 virt)
 {
 	u32 pdi = virt >> 22;
 	u32 pti = (virt >> 12) & 0x03FF;
-	return current_page_directory[pdi][pti] & 0xFFF;
+	return page_tables[pdi][pti] & 0xFFF;
 }
 
 void paging_set_flag_up(u32 virt, u32 count, u32 flag)
 {
 	u32 page_n = virt / PAGE_ALIGN;
 	for (u32 i = page_n; i < page_n + count; i++) {
-		current_page_directory[i / PAGE_COUNT][i % PAGE_COUNT] |= flag;
+		page_tables[i / PAGE_COUNT][i % PAGE_COUNT] |= flag;
 		invlpg(i * PAGE_ALIGN);
 	}
 }
@@ -152,7 +131,7 @@ void paging_set_flag_down(u32 virt, u32 count, u32 flag)
 {
 	u32 page_n = virt / PAGE_ALIGN;
 	for (u32 i = page_n; i < page_n + count; i++) {
-		current_page_directory[i / PAGE_COUNT][i % PAGE_COUNT] &= ~flag;
+		page_tables[i / PAGE_COUNT][i % PAGE_COUNT] &= ~flag;
 		invlpg(i * PAGE_ALIGN);
 	}
 }
@@ -184,8 +163,7 @@ u32 paging_find_pages(u32 count)
 	u32 start_page = 0;
 	for (u32 i = 0; i < PAGE_COUNT; i++) {
 		for (u32 j = 0; j < PAGE_COUNT; j++) {
-			if (!(current_page_directory[i][j] & PT_PRESENT) ||
-			    (current_page_directory[i][j] & PT_USED)) {
+			if (!(page_tables[i][j] & PT_PRESENT) || (page_tables[i][j] & PT_USED)) {
 				continuous = 0;
 				start_dir = i;
 				start_page = j + 1;
@@ -212,7 +190,7 @@ u32 paging_get_used_pages()
 	u32 n = 0;
 	for (u32 i = 0; i < PAGE_COUNT; i++) {
 		for (u32 j = 0; j < PAGE_COUNT; j++) {
-			u8 flags = current_page_directory[i][j] & PT_USED;
+			u8 flags = page_tables[i][j] & PT_USED;
 			if (flags == 1)
 				n++;
 		}
diff --git a/src/kernel/memory/paging.h b/src/kernel/memory/paging.h
index 3d3b176..b7ea07a 100644
--- a/src/kernel/memory/paging.h
+++ b/src/kernel/memory/paging.h
@@ -25,8 +25,7 @@
 #define PT_GLOBAL 1 << 8
 #define PT_USED 1 << 9
 
-u32 **current_page_directory;
-u32 kernel_page_directory[1024] __attribute__((aligned(4096)));
+u32 page_directory[1024] __attribute__((aligned(4096)));
 int paging_enabled;
 
 void paging_install();
@@ -34,6 +33,7 @@ void paging_enable();
 void paging_disable();
 
 u32 **paging_make_directory();
+void paging_remove_directory(u32 **dir);
 void paging_switch_directory(u32 **dir);
 
 void paging_map(u32 phy, u32 virt, u16 flags);
diff --git a/src/kernel/multiboot.c b/src/kernel/multiboot.c
index f7ac876..8bc5242 100644
--- a/src/kernel/multiboot.c
+++ b/src/kernel/multiboot.c
@@ -7,7 +7,7 @@
 #include <stdint.h>
 #include <system.h>
 
-void multiboot_parse(u32 multiboot_address)
+void multiboot_parse()
 {
 	struct multiboot_tag *tag;
 
diff --git a/src/kernel/system.h b/src/kernel/system.h
index 785aa9b..3972151 100644
--- a/src/kernel/system.h
+++ b/src/kernel/system.h
@@ -5,7 +5,12 @@
 #include <stddef.h>
 #include <stdint.h>
 
+// Passed by low level things
 u32 multiboot_address;
+extern u32 text_start;
+extern u32 data_start;
+extern u32 bss_start;
+extern u32 kernel_end;
 
 /**
  * The ASM registers as packed structure
diff --git a/src/kernel/tasks/process.c b/src/kernel/tasks/process.c
index e11cfee..5f70bc7 100644
--- a/src/kernel/tasks/process.c
+++ b/src/kernel/tasks/process.c
@@ -136,8 +136,7 @@ void process_suspend(u32 pid)
 {
 	debug("Suspending process %d", pid);
 	process_print_tree();
-	if (pid == 1)
-		panic("Root process died");
+	assert(pid != 1);
 
 	struct process *proc = process_from_pid(pid);
 
@@ -184,12 +183,7 @@ struct process *process_make_new()
 	proc->registers.ds = 0x23;
 	proc->registers.ss = 0x23;
 	proc->cr3 = paging_make_directory();
-
 	proc->brk = 0x50000000;
-
-	for (int i = 0; i < 1024; i++)
-		proc->cr3[i] = kernel_page_directory[i];
-
 	proc->pid = pid++;
 	return proc;
 }
-- 
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