Move headers to include/

include/mem/gdt.h

@@ -0,0 +1,31 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Global Descriptor Table (for legacy reasons)
+ * @license GPL-3.0-only
+ */
+
+#ifndef GDT_H
+#define GDT_H
+
+#include <stdint.h>
+
+// We're using the GDT for segmentation, but as we want to target Long Mode,
+// we'll only use this as a requirement for paging, not more.
+// This means base 0 and no limit (whole address space)
+
+#define NUM_GDT_ENTRIES 5
+
+#define NULL_SELECTOR 0x00
+#define KERNEL_CODE_SEGMENT 0x08
+#define KERNEL_DATA_SEGMENT 0x10
+#define USER_CODE_SEGMENT 0x18
+#define USER_DATA_SEGMENT 0x20
+
+struct GDTR {
+    uint16_t limit;
+    uint64_t address;
+} __attribute__((packed));
+
+void gdt_init(void);
+
+#endif

include/mem/kheap.h

@@ -0,0 +1,32 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Kernel heap
+ * @license GPL-3.0-only
+ */
+
+#ifndef KHEAP_H
+#define KHEAP_H
+
+// We need some kind of simple kernel heap to make our linked list
+// for the VMM, as we need "malloc" and "free" for that data structure.
+// When the kernel heap is ready, we can alloc our VM object linked list
+// and then continue working on the VMM.
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+struct heap_block_t {
+    size_t size;
+    bool free; // 1byte
+    uint8_t reserved[7]; // (7+1 = 8 bytes)
+    struct heap_block_t* next;
+} __attribute__((aligned(16)));
+
+void kheap_init(void);
+void* kmalloc(size_t size);
+void kfree(void* ptr);
+void* kalloc_stack(void);
+void kheap_map_page(void);
+
+#endif

include/mem/paging.h

@@ -0,0 +1,55 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   x64 4-level paging implementation
+ * @license GPL-3.0-only
+ */
+
+#ifndef PAGING_H
+#define PAGING_H
+
+#define PAGE_SIZE 4096
+
+#include <stdint.h>
+#include <limine.h>
+#include <mem/kheap.h>
+#include <kernel.h>
+
+void paging_init(struct boot_context boot_ctx);
+void paging_map_page(uint64_t* root_table, uint64_t virt, uint64_t phys, uint64_t flags);
+
+// To swap root page tables
+void load_cr3(uint64_t value);
+
+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)
+
+#define PTE_ADDR_MASK 0x000FFFFFFFFFF000
+// Stole it
+#define ALIGN_UP(x, align)   (((x) + ((align) - 1)) & ~((align) - 1))
+#define ALIGN_DOWN(x, align) ((x) & ~((align) - 1))
+#define PAGE_ALIGN_DOWN(x) ((x) & PTE_ADDR_MASK)
+
+#define ALIGN(size) ALIGN_UP(size, 16)
+#define BLOCK_MIN_SIZE (sizeof(struct heap_block_t) + 16)
+
+#define PML4_INDEX(x) (((x) >> 39) & 0x1FF)
+#define PDPT_INDEX(x) (((x) >> 30) & 0x1FF)
+#define PD_INDEX(x)   (((x) >> 21) & 0x1FF)
+#define PT_INDEX(x)   (((x) >> 12) & 0x1FF)
+
+// Page entry special bits
+// Bits set on a parent (directory, table) fall back to their children
+enum PTE_FLAGS
+{
+    PTE_PRESENT = (1ULL << 0),
+    PTE_WRITABLE = (1ULL << 1),
+    PTE_USER = (1ULL << 2),
+    PTE_PWT = (1ULL << 3),
+    PTE_PCD = (1ULL << 4),
+    PTE_HUGE = (1ULL << 7),
+    PTE_NOEXEC = (1ULL << 63)
+};
+
+#endif

include/mem/pmm.h

@@ -0,0 +1,17 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Physical memory manager from freelist
+ * @license GPL-3.0-only
+ */
+
+#ifndef PAGING_PMM_H
+#define PAGING_PMM_H
+
+#include <limine.h>
+#include <kernel.h>
+
+void pmm_init(struct boot_context boot_ctx);
+void pmm_free(uintptr_t addr);
+uintptr_t pmm_alloc(void);
+
+#endif

include/mem/utils.h

@@ -0,0 +1,21 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Common memory utilities
+ * @license GPL-3.0-only
+ */
+
+#ifndef MEM_UTILS_H
+#define MEM_UTILS_H
+
+#include <stddef.h>
+
+void* memcpy(void* restrict dest, const void* restrict src, size_t n);
+void* memset(void* s, int c, size_t n);
+void* memmove(void *dest, const void* src, size_t n);
+int memcmp(const void* s1, const void* s2, size_t n);
+
+// DEBUG
+void memmap_display(struct limine_memmap_response* response);
+void hhdm_display(struct limine_hhdm_response* hhdm);
+
+#endif

include/mem/vmm.h

@@ -0,0 +1,34 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Virtual memory manager
+ * @license GPL-3.0-only
+ */
+
+#ifndef VMM_H
+#define VMM_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+/*
+This will be our linked list of virtual memory objects.
+Flags here aren't x86 flags, they are platform-agnostic
+kernel-defined flags.
+*/
+
+struct vm_object {
+    uintptr_t base;
+    size_t length;
+    size_t flags;
+    struct vm_object* next;
+};
+
+// Flags bitfield
+#define VM_FLAG_NONE 0
+#define VM_FLAG_WRITE (1 << 0)
+#define VM_FLAG_EXEC (1 << 1)
+#define VM_FLAG_USER (1 << 2)
+
+void vmm_init(void);
+
+#endif