Makefile

@@ -1,8 +1,8 @@
-SOURCES = src/mem/paging/pmm.c src/string/string.c src/io/kbd/ps2.c src/io/serial/serial.c src/io/term/printf.c src/io/term/term.c src/idt/idt.c src/mem/gdt/gdt.c src/mem/misc/utils.c src/time/timer.c src/kmain.c
+SOURCES = src/mem/paging/paging.c src/mem/paging/pmm.c src/string/string.c src/io/kbd/ps2.c src/io/serial/serial.c src/io/term/printf.c src/io/term/term.c src/idt/idt.c src/mem/gdt/gdt.c src/mem/misc/utils.c src/time/timer.c src/kmain.c
 
 build:
 	rm -f *.o
-	x86_64-elf-gcc -g -c -I src $(SOURCES) -Wall -Wextra -std=gnu99 -nostdlib -ffreestanding -fno-stack-protector -fno-stack-check -fno-PIC -ffunction-sections -fdata-sections -mcmodel=kernel
+	x86_64-elf-gcc -g -c -Isrc $(SOURCES) -Wall -Wextra -std=gnu99 -nostdlib -ffreestanding -fno-stack-protector -fno-stack-check -fno-PIC -ffunction-sections -fdata-sections -mcmodel=kernel
 	objcopy -O elf64-x86-64 -B i386 -I binary zap-light16.psf zap-light16.o
 	nasm -f elf64 src/idt/idt.S -o idt_stub.o
 	x86_64-elf-ld -o pepperk -T linker.ld *.o

src/idt/idt.c

@@ -1,8 +1,8 @@
 #include "idt.h"
 #include <stdint.h>
 #include <stddef.h>
-#include "../io/serial/serial.h"
+#include "io/serial/serial.h"
-#include "../io/kbd/ps2.h"
+#include "io/kbd/ps2.h"
 #include <kernel.h>
 
 struct interrupt_descriptor idt[256];

src/io/kbd/ps2.c

@@ -1,9 +1,9 @@
 // PS/2 Keyboard support
 
-#include "../serial/serial.h"
+#include "io/serial/serial.h"
 #include "ps2.h"
 #include <stdint.h>
-#include "../term/term.h"
+#include "io/term/term.h"
 #include <kernel.h>
 
 // The key status bitfield will be used to see if ALT, CONTROL, or SHIFT is pressed

src/kmain.c

@@ -11,6 +11,7 @@
 #include "time/timer.h"
 #include "io/kbd/ps2.h"
 #include "mem/paging/pmm.h"
+#include "mem/paging/paging.h"
 
 // Limine version used
 __attribute__((used, section(".limine_requests")))
@@ -73,6 +74,7 @@ void kmain()
 	hhdm_display(hhdm_request.response);
 
 	pmm_init(memmap_request.response, hhdm_request.response);
+	paging_init();
 
 	CLEAR_INTERRUPTS;
 	gdt_init();

src/mem/gdt/gdt.c

@@ -1,6 +1,6 @@
 #include "gdt.h"
 #include <stdint.h>
-#include "../../io/serial/serial.h"
+#include "io/serial/serial.h"
 #include <kernel.h>
 
 // Descriptors are 8-byte wide (64bits)

src/mem/misc/utils.c

@@ -1,8 +1,8 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <limine.h>
-#include "../../kernel.h"
+#include "kernel.h"
-#include "../../string/string.h"
+#include "string/string.h"
 
 // We won't be linked to standard library, but still need the basic mem* functions
 // so everything goes allright with the compiler

src/mem/paging/paging.c

@@ -0,0 +1,13 @@
+#include "paging.h"
+#include <kernel.h>
+
+void paging_init()
+{
+    uint64_t cr3;
+    asm volatile ("mov %%cr3, %0" : "=r"(cr3));
+
+    // Root directory address (cr3 without 12 less significant bits)
+    uint64_t* pml4 = PHYS_TO_VIRT(cr3 & ~0xFFF);
+
+    DEBUG("pml4=0x%p", pml4);
+}

src/mem/paging/paging.h

@@ -1,16 +1,29 @@
-#ifndef PAGING_PMM_H
+#ifndef PAGING_H
-#define PAGING_PMM_H
+#define PAGING_H
-
-/*
-We are going to use a bitmap, consisting of an array of uint64_t
-to represent pages for the PMM (physical memory manager).
-
-Bit set (1) = page used
-Bit clear (0) = page free
-
-*/
 
 #define PAGE_SIZE 4096
 #define BITS_PER_ROW 64
 
+#include <stdint.h>
+
+void paging_init();
+
+extern uint64_t hhdm_off;
+
+#define PHYS_TO_VIRT(x) ((void*)((uintptr_t)(x) + hhdm_off))
+#define VIRT_TO_PHYS(x) ((uintptr_t)(x) - hhdm_off)
+
+// Stole it
+#define ALIGN_UP(x, align)   (((x) + ((align) - 1)) & ~((align) - 1))
+#define ALIGN_DOWN(x, align) ((x) & ~((align) - 1))
+
+// Page entry special bits
+// Bits set on a parent (directory, table) fall back to their children
+#define PTE_PRESENT  (1ULL << 0)
+#define PTE_WRITE    (1ULL << 1)
+#define PTE_USER     (1ULL << 2)
+#define PTE_HUGE     (1ULL << 7)
+#define PTE_NOEXEC   (1ULL << 63)
+
+
 #endif

src/mem/paging/pmm.c

@@ -12,7 +12,7 @@ to see which pages are used by kernel/bootloader/mmio/fb etc.
 #include <stddef.h>
 #include <stdint.h>
 #include <kernel.h>
-#include "../misc/utils.h"
+#include "mem/misc/utils.h"
 #include "pmm.h"
 
 /*
@@ -27,42 +27,6 @@ and use this for the bitmap. The reserved memory will be ignored.
 
 struct usable_memory* usable_mem;
 struct limine_memmap_entry* biggest_entry;
-/* 
-uint64_t* bitmap;
-uint64_t* usable_memory_begin;
-
-// Bitmap will be placed at the start of the biggest usable region
-// 1 bitmap page = 4096 bytes = 32768 bits
-// So 1 bitmap page can track up to 32768 pages of memory
-static void pmm_allocate_bitmap(struct limine_hhdm_response* hhdm)
-{
-    uint64_t pages = biggest_entry->length / PAGE_SIZE;
-    uint64_t bitmap_items = (pages+BITS_PER_ROW-1)/BITS_PER_ROW;
-    DEBUG("we need %u pages (bits) that will fit in %u uint64_t", pages, bitmap_items);
-
-    bitmap = (uint64_t*)(biggest_entry->base + hhdm->offset);
-    DEBUG("bitmap will live at 0x%p", bitmap);
-
-    uint64_t bitmap_bytes = bitmap_items*sizeof(uint64_t);
-
-    // All pages are marked free since we're in a USABLE region
-    memset(bitmap, 0x00, bitmap_bytes);
-
-    uint64_t bitmap_pages = (bitmap_bytes + PAGE_SIZE - 1) / PAGE_SIZE;
-
-    // The 1st memory page we can use is at bitmap + bitmap_pages
-    usable_memory_begin = (void*)((uintptr_t)bitmap + bitmap_pages*PAGE_SIZE);
-
-    // Mark bitmap as allocated
-    for (uint64_t i=0; i<bitmap_pages; i++)
-    {
-        uint64_t row = i / BITS_PER_ROW;
-        uint64_t bit = i % BITS_PER_ROW;
-        bitmap[row] |= (1ULL << bit);
-    }
-
-    DEBUG("bitmap occupies %u pages", bitmap_pages);
-} */
 
 static void pmm_find_biggest_usable_region(struct limine_memmap_response* memmap, struct limine_hhdm_response* hhdm)
 {
@@ -97,13 +61,6 @@ uint64_t hhdm_off;
 
 static uintptr_t g_freelist = 0;
 
-#define PHYS_TO_VIRT(x) ((void*)((uintptr_t)(x) + hhdm_off))
-#define VIRT_TO_PHYS(x) ((uintptr_t)(x) - hhdm_off)
-
-// Stole it
-#define ALIGN_UP(x, align)   (((x) + ((align) - 1)) & ~((align) - 1))
-#define ALIGN_DOWN(x, align) ((x) & ~((align) - 1))
-
 uintptr_t pmm_alloc()
 {
     if (!g_freelist) return 0;
@@ -130,8 +87,9 @@ static void pmm_init_freelist()
     {
         pmm_free(addr);
         //DEBUG("page %u lives at phys 0x%p (virt 0x%p)", page_count, addr, PHYS_TO_VIRT(addr));
-        //page_count++;
+        page_count++;
     }
+    DEBUG("%u frames in freelist, available for use (%u bytes)", page_count, page_count*PAGE_SIZE);
 }
 
 void pmm_init(struct limine_memmap_response* memmap, struct limine_hhdm_response* hhdm)
@@ -143,6 +101,4 @@ void pmm_init(struct limine_memmap_response* memmap, struct limine_hhdm_response
     // Now we have biggest USABLE region,
     // so to populate the free list we just iterate through it
     pmm_init_freelist();
-
-    DEBUG("Trying pmm_alloc gives us page at 0x%p", pmm_alloc());
 }

src/time/timer.c

@@ -1,5 +1,5 @@
 #include <stdint.h>
-#include "../io/serial/serial.h"
+#include "io/serial/serial.h"
 #include <kernel.h>
 
 /*