Small adjustment in directory structure of memory and bootloader files in kernel

This commit is contained in:
2021-11-02 21:15:00 +01:00
parent c9b789ed7b
commit bdcf9e66f8
11 changed files with 17 additions and 137 deletions

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#include "PageDirectory.h"
#include <stdint.h>
void PageDirectory::enable(){
//set each entry to not present
int i;
for(i = 0; i < 1024; i++)
{
// This sets the following flags to the pages:
// Supervisor: Only kernel-mode can access them
// Write Enabled: It can be both read from and written to
// Not Present: The page table is not present
this->page_directory[i] = 0x00000002;
}
// holds the physical address where we want to start mapping these pages to.
// in this case, we want to map these pages to the very beginning of memory.
//we will fill all 1024 entries in the table, mapping 4 megabytes
for(unsigned int i = 0; i < 1024; i++)
{
// As the address is page aligned, it will always leave 12 bits zeroed.
// Those bits are used by the attributes ;)
first_page_table[i] = (i * 0x1000) | 3; // attributes: supervisor level, read/write, present.
}
// attributes: supervisor level, read/write, present
this->page_directory[0] = ((unsigned int)first_page_table) | 3;
loadPageDirectory(this->page_directory);
enablePaging();
}
/*
void IdentityPaging(uint32_t *first_pte, vaddr from, int size)
{
from = from & 0xFFFFF000; // Discard the bits we don't want
for (; size > 0; from += 4096, first_pte++)
{
*first_pte = from | 1; // makr page present.
}
}
*/

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#pragma once
#include <stdint.h>
extern "C" void loadPageDirectory (uint32_t* addr );
extern "C" void enablePaging();
typedef uintptr_t address_t;
#define KB 1024
static const int MAX_PAGES = 1024 * KB; // 4GB , 4kB/page
static volatile address_t pmem_stack[MAX_PAGES];
static volatile address_t pmem_stack_top = MAX_PAGES; // top down allocation
struct page_directory_entry {};
struct page_table_entry{};
class PageDirectory {
public:
void enable ();
private:
uint32_t page_directory[1024] __attribute__((aligned(4096)));
uint32_t first_page_table[1024] __attribute__((aligned(4096)));
};

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#include "PageFrameAllocator.h"

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#pragma once
#include <stdint.h>
extern void *kernel_begin;
extern void *kernel_end;

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#pragma once
/**
* We'll need something to this effect to allocate memory in the kernel
* this will hopefully someday implement a full slab allocator
**/
enum SlabState {
empty,
partial,
full
};
class CacheSlab {
const int SlabSize = 4000;
void* start = 0x0;
};
class Allocator {
public:
Allocator();
~Allocator();
void* kmalloc( int size );
void kfree (void* address);
private:
CacheSlab** _cache;
};