paging done

README.md

@@ -29,3 +29,8 @@ slowly porting from rust.
 ## interrupts
 
 `interrupt` -> `idt[n]` -> `isrN` -> `isrDispatch` -> `handlers[n]` (default `unhandled()`)
+
+## layout
+
+`0->4Mib` kernel reserved
+`1Mib` interrupt stack

qemu.sh

@@ -12,10 +12,11 @@ start() {
         -m 1337M \
         -curses \
         -append "Hello" \
+        -drive file=disk.img,if=virtio\
         -kernel ${KERNEL}
+        # -no-reboot \
         # -device virtio-net,netdev=network0 -netdev tap,id=network0,ifname=tap0,script=no,downscript=no \
 	# build/kernel.iso
-        "$@"
 
         # this allows this switch to monitor with ^a-c, but doesn't
         # play nice with irqs apparently...

src/arch/x86/_start.s

@@ -8,6 +8,7 @@ __start:
 
     push %ebx   // Pass multiboot info structure.
     push %eax   // Pass multiboot magic code.
+
     call kmain  // Call the kernel.
 
     // Halt the CPU.

src/arch/x86/gdt.zig

@@ -125,9 +125,9 @@ pub fn initialize() void {
     loadGDT(&gdtr);
 
     // Initialize TSS.
-    const tss_entry = makeEntry(@ptrToInt(&tss), @sizeOf(TSS) - 1, TSS_ACCESS, PROTECTED);
+    // const tss_entry = makeEntry(@ptrToInt(&tss), @sizeOf(TSS) - 1, TSS_ACCESS, PROTECTED);
-    gdt[TSS_DESC / @sizeOf(GDTEntry)] = tss_entry;
+    // gdt[TSS_DESC / @sizeOf(GDTEntry)] = tss_entry;
-    x86.ltr(TSS_DESC);
+    // x86.ltr(TSS_DESC);
 
     // tty.stepOK();
 }

src/arch/x86/isr.s

@@ -1,5 +1,5 @@
 // Kernel stack for interrupt handling.
-KERNEL_STACK = 0x800000
+KERNEL_STACK = 0x10000
 // GDT selectors.
 KERNEL_DS = 0x10
 

src/arch/x86/layout.zig

@@ -0,0 +1,6 @@
+//https://wiki.osdev.org/Memory_Map_(x86)
+
+pub const KSTACK = 0x80000; // todo: move to .bss
+pub const KERNEL = 0x100000;
+pub const IDENTITY = 0x400000; // 0->4MiB
+pub const HEAP = 0x800000;

src/arch/x86/linker.ld

@@ -8,7 +8,7 @@ SECTIONS {
 	. = 0xb8000;
 	. += 80 * 25 * 2;
 
-    /* lower half kernel */
+    /* lower half kernel <1MiB */
 	. = 0x10000;
 
 	/* ensure that the multiboot header is at the beginning */
@@ -37,32 +37,12 @@ SECTIONS {
 		. = ALIGN(4K);
 	}
 
-	/* NOT A GOOD IDEA TO GROUP debug_* SYMBOLS ! */
-	/* .debug : */
-	/* { */
-	/* 	/1* KEEP(*(.debug_*)) *1/ */
-	/* 	*(.debug_*) */
-	/* 	. = ALIGN(4K); */
-	/* } */
-
 	.gdt :
 	{
 		*(.gdt)
 		. = ALIGN(4K);
 	}
 
-	.got :
-	{
-		*(.got)
-		. = ALIGN(4K);
-	}
-
-	.got.plt :
-	{
-		*(.got.plt)
-		. = ALIGN(4K);
-	}
-
 	.bss :
 	{
 		*(.bss .bss.*)

src/arch/x86/main.zig

@@ -12,26 +12,11 @@ const x86 = @import("lib/index.zig");
 /// x86 specific intialization
 /// first entry point (see linker.ld)
 pub fn x86_main(info: *const MultibootInfo) void {
-    // set up the physical frame allocator
-    memory.initialize(info);
-
-    println("{}", memory.allocator.allocate(1));
-    // println("{}", memory.allocator.allocate(1));
-    // println("{}", memory.allocator.allocate(1));
-    // println("{}", memory.allocator.allocate(1));
-
-    // setup memory segmentation
     gdt.initialize();
-
-    // setup interrupts
     idt.initialize();
+    memory.initialize(info);
+    paging.initialize();
 
     // enable interrupts
     x86.sti();
-
-    // set up the virtual page mapper
-    paging.initialize();
-
-    // test breakpoint
-    // x86.int3();
 }

src/arch/x86/memory.zig

@@ -1,124 +1,88 @@
 usingnamespace @import("kernel").multiboot;
-usingnamespace @import("../../vga.zig");
+usingnamespace @import("kernel").vga;
 const assert = @import("std").debug.assert;
-const std = @import("std");
 
-pub var allocator: bumpAllocator = undefined;
+var stack: [*]usize = undefined; // Stack of free physical page.
+var stack_index: usize = 0; // Index into the stack.
 
+// Boundaries of the frame stack.
+pub var stack_size: usize = undefined;
+pub var stack_end: usize = undefined;
+
+pub const PAGE_SIZE: usize = 4096;
+// 4095 -> 4096
+// 4096 -> 4096
+// 4097 -> 8192
+pub fn pageAlign(address: u32) u32 {
+    return (address + PAGE_SIZE - 1) & (~PAGE_SIZE +% 1);
+}
+
+////
+// Return the amount of variable elements (in bytes).
+//
+pub fn available() usize {
+    return stack_index * PAGE_SIZE;
+}
+
+////
+// Request a free physical page and return its address.
+//
+pub fn allocate() ?usize {
+    if (available() == 0) {
+        println("out of memory");
+        return null;
+    }
+
+    stack_index -= 1;
+    return stack[stack_index];
+}
+
+////
+// Free a previously allocated physical page.
+//
+// Arguments:
+//     address: Address of the page to be freed.
+//
+pub fn free(address: usize) void {
+    stack[stack_index] = address;
+    stack_index += 1;
+}
+
+////
+// Scan the memory map to index all available memory.
+//
+// Arguments:
+//     info: Information structure from bootloader.
+//
 pub fn initialize(info: *const MultibootInfo) void {
+    // Ensure the bootloader has given us the memory map.
     assert((info.flags & MULTIBOOT_INFO_MEMORY) != 0);
     assert((info.flags & MULTIBOOT_INFO_MEM_MAP) != 0);
 
-    format_multibootinfo(info);
+    // Place the stack of free pages after the last Multiboot module.
-    allocator = bumpAllocator.new(info);
+    stack = @intToPtr([*]usize, 0x200000);
-}
+    // stack = @intToPtr([*]usize, pageAlign(info.mods_addr));
-
+    // Calculate the approximate size of the stack based on the amount of total upper memory.
-fn format_multibootentry(entry: *MultibootMMapEntry) void {
+    stack_size = ((info.mem_upper * 1024) / PAGE_SIZE) * @sizeOf(usize);
-    if (entry.type == MULTIBOOT_MEMORY_AVAILABLE) {
+    stack_end = pageAlign(@ptrToInt(stack) + stack_size);
-        print("    AVAILABLE: ");
-    } else {
-        print("NOT AVAILABLE: ");
-    }
-    print("{x} ", entry.addr);
-    if (entry.len / (1024 * 1024) > 0) {
-        println("({} MB)", entry.len / (1024 * 1024));
-    } else {
-        println("({} kB)", entry.len / (1024));
-    }
-}
-
-fn format_multibootinfo(info: *const MultibootInfo) void {
-    var cmdline_ptr = @intToPtr([*c]const u8, info.cmdline);
-    var cmdline = @ptrCast([*c]const u8, cmdline_ptr);
-    // var cmdline = std.cstr.toSliceConst(info.cmdline);
-    println("flags: {b}", info.flags);
-    println("lower: {x}", info.mem_lower);
-    println("upper: {x}", info.mem_upper);
-    println("mmap_l: {}", info.mmap_length);
-    println("mmap_a: {x}", info.mmap_addr);
-    println("cmdline: {x}", cmdline_ptr);
-    println("cmdline: {}", cmdline);
 
     var map: usize = info.mmap_addr;
     while (map < info.mmap_addr + info.mmap_length) {
         var entry = @intToPtr(*MultibootMMapEntry, map);
-        format_multibootentry(entry);
+
+        // Calculate the start and end of this memory area.
+        var start = @truncate(usize, entry.addr);
+        var end = @truncate(usize, start + entry.len);
+        // Anything that comes before the end of the stack of free pages is reserved.
+        start = if (start >= stack_end) start else stack_end;
+
+        // Flag all the pages in this memory area as free.
+        if (entry.type == MULTIBOOT_MEMORY_AVAILABLE) while (start < end) : (start += PAGE_SIZE)
+            free(start);
+
+        // Go to the next entry in the memory map.
         map += entry.size + @sizeOf(@typeOf(entry.size));
     }
+
+    println("available memory: {d} MiB ", available() / 1024 / 1024);
 }
-
-// returns each available physical frame one by one in order
-pub const bumpAllocator = struct {
-    next_free_frame: PhysFrame,
-    current_area: ?*MultibootMMapEntry,
-    info: *const MultibootInfo,
-
-    pub fn new(info: *const MultibootInfo) bumpAllocator {
-        const first_area = @intToPtr(*MultibootMMapEntry, info.mmap_addr);
-        var allocato = bumpAllocator{
-            .current_area = first_area,
-            .next_free_frame = PhysFrame.from_addr(@intCast(u32, first_area.addr)),
-            .info = info,
-        };
-        return allocato;
-    }
-
-    pub fn allocate(self: var, count: u32) ?PhysFrame {
-        if (count == 0) {
-            return null;
-        }
-        if (self.current_area == null) {
-            return null;
-        }
-        if (self.current_area.?.type != MULTIBOOT_MEMORY_AVAILABLE) {
-            self.choose_next_area();
-            return self.allocate(count);
-        }
-        // <4MB identity mapped kernel, lazy trick
-        if (PhysFrame.start_addr(self.next_free_frame) < 0x400000) {
-            self.next_free_frame.number += 1;
-            return self.allocate(count);
-        }
-
-        const start_frame = self.next_free_frame;
-        const end_frame = self.next_free_frame.add(count - 1);
-        const current_area_last_frame = PhysFrame.from_addr(@intCast(u32, self.current_area.?.addr + self.current_area.?.len));
-        if (end_frame.number > current_area_last_frame.number) {
-            self.choose_next_area();
-            return self.allocate(count);
-        }
-        self.next_free_frame.number += count;
-        return start_frame;
-    }
-
-    pub fn choose_next_area(self: var) void {
-        println("choosing next area");
-        const current = self.current_area.?;
-        var next_area = @ptrToInt(current) + current.size + @sizeOf(@typeOf(current));
-        if (next_area >= self.info.mmap_addr + self.info.mmap_length) {
-            self.current_area = null;
-        } else {
-            self.current_area = @intToPtr(*MultibootMMapEntry, next_area);
-            format_multibootentry(self.current_area.?);
-            self.next_free_frame = PhysFrame.from_addr(@intCast(u32, self.current_area.?.addr));
-        }
-    }
-};
-
-pub const PAGE_SIZE = 4096;
-
-pub const PhysFrame = struct {
-    number: u32,
-
-    pub fn from_addr(addr: u32) PhysFrame {
-        return PhysFrame{ .number = @divTrunc(addr, PAGE_SIZE) };
-    }
-
-    pub fn add(self: PhysFrame, count: u32) PhysFrame {
-        return PhysFrame{ .number = self.number + count };
-    }
-
-    pub fn start_addr(self: PhysFrame) u32 {
-        return (self.number * PAGE_SIZE);
-    }
-};

src/arch/x86/paging.s

@@ -11,13 +11,15 @@ setupPaging:
   mov +4(%esp), %eax  // Fetch the phys_pd parameter.
   mov %eax, %cr3      // Point CR3 to the page directory.
 
-  // Enable Page Size Extension and Page Global.
+  // Enable Page Size Extension
   mov %cr4, %eax
-  or $0b00010000, %eax
+  or $0x10, %eax
   mov %eax, %cr4
 
   // Enable Paging.
   mov %cr0, %eax
+  mov $1, %eax
+  or $(1 << 0), %eax
   or $(1 << 31), %eax
   mov %eax, %cr0
 

src/arch/x86/paging.zig

@@ -1,89 +1,102 @@
 const x86 = @import("lib/index.zig");
-const allocator = @import("memory.zig").allocator;
+const memory = @import("memory.zig");
+const interrupt = @import("interrupt.zig");
 const assert = @import("std").debug.assert;
 const println = @import("../../vga.zig").println;
 
 extern fn setupPaging(phys_pd: usize) void;
 
-pub var mapper: Mapper = undefined;
+const PageEntry = usize;
 pub const PAGE_SIZE = 4096;
+pub const PT = @intToPtr([*]PageEntry, 0xFFC00000);
+pub const PD = @intToPtr([*]PageEntry, 0xFFFFF000);
+const PRESENT = 0x1;
+const WRITE = 0x2;
+const USER = 0x4;
+const WRITE_THRU = 0x8;
+const NOCACHE = 0x10;
+const ACCESSED = 0x20;
+const HUGE = 0x80;
+
+pub var pageDirectory: [1024]PageEntry align(4096) linksection(".bss") = [_]PageEntry{0} ** 1024;
+
+fn pageFault() void {
+    println("pagefault");
+    while (true) {
+        asm volatile ("hlt");
+    }
+}
+
+fn pageBase(addr: usize) usize {
+    return addr & (~PAGE_SIZE +% 1);
+}
+fn pde(addr: usize) *PageEntry {
+    return &PD[addr >> 22];
+}
+fn pte(addr: usize) *PageEntry {
+    return &PT[addr >> 12];
+}
+
+// virtual to physical
+pub fn translate(virt: usize) ?usize {
+    if (pde(virt).* == 0) return null;
+    return pageBase(pte(virt).*);
+}
+
+pub fn unmap(virt: usize) void {
+    var pte = pte(virt);
+    if (pte.* == 0) {
+        println("can't unmap 0x{x}, map is empty.", addr);
+        return;
+    }
+    pte.* = 0;
+    memory.free(translate(virt));
+}
+
+pub fn mmap(virt: usize, phys: ?usize) void {
+    var pde: *PageEntry = &PD[virt >> 22];
+    if (pde.* == 0) {
+        pde.* = memory.allocate() | WRITE | PRESENT;
+    }
+    var pte: *PageEntry = &PT[virt >> 12];
+    pte.* = if (phys) |p| p else allocate() | PRESENT;
+}
+
+pub fn addrspace() void {
+    var i: usize = 1;
+    i = 0;
+    while (i < 1024) : (i += 1) {
+        if (PD[i] == 0) {
+            continue;
+        }
+        println("p2[{}] -> 0x{x}", i, PD[i]);
+        if (PD[i] & HUGE != 0) {
+            continue;
+        }
+        var j: usize = 0;
+        while (j < 1024) : (j += 1) {
+            var entry: PageEntry = PT[i * 1024 + j];
+            if (entry != 0) {
+                println("p2[{}]p1[{}] -> 0x{x}", i, j, entry);
+            }
+        }
+    }
+}
 
 pub fn initialize() void {
-    const empty_page = PageDirectoryEntry{};
+    var p2 = pageDirectory[0..];
-    // var p2 = allocator.allocate(1);
-    var p2 = [_]PageDirectoryEntry{empty_page} ** 1024;
-    // var p2 = [_]u32{0} ** 1024;
-
     // identity map 0 -> 4MB
-    p2[0].pageTable = 0x0;
-    p2[0].present = true;
-    p2[0].read_write = true;
-    p2[0].huge = true;
-    // p2[0] = @bitReverse(u32, 0b10000011);
 
-    println("p2[0] {b}", p2[0]);
+    p2[0] = 0x000000 | PRESENT | WRITE | HUGE;
-    println("p2[0] {b}", @bitCast(u32, p2[0]));
+    p2[1023] = @ptrToInt(&p2[0]) | PRESENT | WRITE;
-    // x86.hang();
-    // paging.s
-    // setupPaging(@ptrToInt(&p2));
 
-    // mapper = Mapper{
+    assert(memory.stack_end < 0x400000);
-    //     .p2 = p2,
+    // const first: *u32 = @ptrCast(*u32, p2);
-    // };
+    // println("p2[0] {b}", first.*);
-    const addr = mapper.translate(0xfffff000);
+
-}
+    interrupt.register(14, pageFault);
-
+    setupPaging(@ptrToInt(&pageDirectory[0]));
-const builtin = @import("builtin");
+
-const Mapper = struct {
+    addrspace();
-    p2: PageDirectory,
+    // const addr = mapper.translate(0xfffff000);
-
-    // virt to phys
-    pub fn translate(self: Mapper, virt: u32) ?u32 {
-        const map = @bitCast(VirtAddr, virt);
-        println("{}", builtin.endian);
-        println("virt {x} -> {}-{}-{x}", virt, map.page_directory, map.page_table, map.offset);
-        return null;
-    }
-};
-
-pub const VirtAddr = packed struct {
-    page_directory: u10,
-    page_table: u10,
-    offset: u12,
-};
-
-pub const PageDirectoryEntry = packed struct {
-    pageTable: u20 = 0,
-    available: u3 = 0,
-    ignored: bool = false,
-    huge: bool = false,
-    zero: bool = false,
-    accessed: bool = false,
-    cache_disabled: bool = false,
-    write_thru: bool = false,
-    supervisor: bool = false,
-    read_write: bool = false,
-    present: bool = false,
-};
-
-pub const PageTableEntry = packed struct {
-    addr: u20 = 0,
-    available: u3 = 0,
-    global: bool = false,
-    zero: bool = false,
-    dirty: bool = false,
-    accessed: bool = false,
-    cache_disabled: bool = false,
-    write_thru: bool = false,
-    supervisor: bool = false,
-    read_write: bool = false,
-    present: bool = false,
-};
-
-pub const PageTable = [1024]PageTableEntry;
-pub const PageDirectory = [1024]PageDirectoryEntry;
-
-comptime {
-    assert(@sizeOf(PageDirectoryEntry) == 4); //32 bits
-    assert(@sizeOf(PageTableEntry) == 4); //32 bits
 }

src/console.zig

@@ -40,7 +40,6 @@ pub fn keypress(char: u8) void {
 }
 
 pub fn initialize() void {
-    // vga.clear();
     interrupt.registerIRQ(1, ps2.keyboard_handler);
     vga.writeString("> ");
 }

src/main.zig

@@ -8,9 +8,11 @@ const assert = @import("std").debug.assert;
 
 // arch independant initialization
 export fn kmain(magic: u32, info: *const MultibootInfo) noreturn {
+    clear();
     assert(magic == MULTIBOOT_BOOTLOADER_MAGIC);
 
     println("--- x86 initialization ---");
+
     x86.x86_main(info);
 
     // pagefault_test(0xfeffc000);

src/memory.zig

@@ -0,0 +1,8 @@
+const paging = @import("arch/x86/paging.zig");
+
+pub fn alloc(size: usize) usize {
+    
+}
+
+pub fn free() {
+}

src/multiboot.zig

@@ -81,8 +81,12 @@ pub const MultibootInfo = packed struct {
     // Return the ending address of the last module.
     //
     pub fn lastModuleEnd(self: *const MultibootInfo) usize {
+        if (self.mods_count > 0) {
             const mods = @intToPtr([*]MultibootModule, self.mods_addr);
             return mods[self.mods_count - 1].mod_end;
+        } else {
+            return self.mods_addr;
+        }
     }
 
     ////

src/pci.zig

@@ -17,31 +17,28 @@ pub const PciDevice = struct {
     bus: u8,
     slot: u5,
     function: u3,
-    device: u16,
+    device: u16 = undefined,
-    vendor: u16,
+    vendor: u16 = undefined,
-    class: u8,
+    class: u8 = undefined,
-    subclass: u8,
+    subclass: u8 = undefined,
-    header_type: u8,
+    header_type: u8 = undefined,
+    driver: ?Driver = null,
 
     pub fn init(bus: u8, slot: u5, function: u3) ?PciDevice {
-        var pcidevice = PciDevice{
+        var dev = PciDevice{
             .bus = bus,
             .slot = slot,
             .function = function,
-            .device = undefined,
-            .class = undefined,
-            .subclass = undefined,
-            .header_type = undefined,
-            .vendor = undefined,
         };
-        pcidevice.vendor = pci_config_read_word(pcidevice, 0);
+        dev.vendor = dev.pci_config_read_word(0);
-        if (pcidevice.vendor == 0xffff)
+        if (dev.vendor == 0xffff)
             return null;
-        pcidevice.device = pci_config_read_word(pcidevice, 2);
+        dev.device = dev.pci_config_read_word(2);
-        pcidevice.subclass = pci_config_read_byte(pcidevice, 10);
+        dev.subclass = dev.pci_config_read_byte(10);
-        pcidevice.class = pci_config_read_byte(pcidevice, 11);
+        dev.class = dev.pci_config_read_byte(11);
-        pcidevice.header_type = pci_config_read_byte(pcidevice, 14);
+        dev.header_type = dev.pci_config_read_byte(14);
-        return (pcidevice);
+        dev.driver = dev.get_driver();
+        return (dev);
     }
 
     pub fn address(self: PciDevice, offset: u8) u32 {
@@ -57,7 +54,11 @@ pub const PciDevice = struct {
     }
 
     pub fn format(self: PciDevice) void {
-        println("{}:{}.{} {x},{x}: {x} {x}", self.bus, self.slot, self.function, self.class, self.subclass, self.vendor, self.device);
+        print("{}:{}.{}", self.bus, self.slot, self.function);
+        print(" {x},{x}: {x} {x}", self.class, self.subclass, self.vendor, self.device);
+        if (self.driver) |d|
+            print(" {}", d.name);
+        println("");
     }
 
     pub fn access(self: PciDevice, offset: u8) void {
@@ -78,13 +79,33 @@ pub const PciDevice = struct {
         self.access(offset);
         return (arch.inl(PCI_CONFIG_DATA));
     }
+
+    pub fn get_driver(self: PciDevice) ?Driver {
+        var i: usize = 0;
+        while (i < Drivers.len) : (i += 1) {
+            var driver = Drivers[i];
+            if (self.class == driver.class and self.subclass == driver.subclass and (driver.vendor == null or self.vendor == driver.vendor.?)) {
+                return driver;
+            }
+        }
+        return null;
+    }
 };
 
+const Driver = struct {
+    name: [*]u8,
+    class: u8,
+    subclass: u8,
+    vendor: ?u16 = null,
+};
+
+const name = "virtio-blk";
+pub var Drivers: [1]Driver = [_]Driver{Driver{ .name = &name, .class = 0x1, .subclass = 0x0, .vendor = 0x1af4 }};
+
 pub fn lspci() void {
     var slot: u5 = 0;
     while (true) {
         if (PciDevice.init(0, slot, 0)) |device| {
-            device.format();
             var function: u3 = 0;
             while (true) {
                 if (PciDevice.init(0, slot, function)) |vf|

src/vga.zig

@@ -63,6 +63,9 @@ pub fn print(comptime format: []const u8, args: ...) void {
 pub fn println(comptime format: []const u8, args: ...) void {
     var a = std.fmt.format({}, Errors, printCallback, format ++ "\n", args);
 }
+pub fn clear() void {
+    vga.clear();
+}
 
 fn printCallback(context: void, string: []const u8) Errors!void {
     vga.writeString(string);