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KERNEL: First Kernel heap implementation

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This commit is contained in:
Nigel Barink 2022-09-03 17:27:29 +02:00
parent 656ca0baa8
commit a47879f404
8 changed files with 83 additions and 51 deletions
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15
source/kernel/kernel.cpp
View File

@ -38,11 +38,9 @@ extern "C" void kernel_main ()
extern "C" void early_main()
{
init_serial();
print_serial("Hello Higher half kernel!\n");
kterm_init();
printf("Allocated blocks: %d \n", GetUsedBlocks());
printf("Allocated blocks: 0x%x \n", GetUsedBlocks());
initGDT();
init_idt();
@ -53,8 +51,12 @@ extern "C" void early_main()
initHeap();
printf("TRY ALLOCATING 4 BYTES\n");
uint32_t* MyVariable = (uint32_t*) malloc(4); // allocate 4 bytes using my heap
free(MyVariable);
// test heap allocation
/*
struct KernelInfo {
int bar;
bool foo;
@ -64,9 +66,10 @@ extern "C" void early_main()
MyInfo->bar = 6;
MyInfo->foo = false;
printf("bar contains %d\n", MyInfo->bar);
free(MyInfo);
*/
printf("Enable Protected mode and jump to kernel main\n");

43
source/kernel/memory/KernelHeap.cpp
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@ -1,4 +1,5 @@
#include "KernelHeap.h"
#include "VirtualMemoryManager.h"
// Size of heap meta data is 5 bytes
struct heap_block{
@ -11,7 +12,7 @@ heap_block* start ;
void* malloc(size_t size)
{
printf("Received request for %d bytes of memory", size);
printf("Received request for %d bytes of memory\n", size);
heap_block* current = start;
// look for a free block
@ -20,8 +21,21 @@ void* malloc(size_t size)
if(current->Size >= size && current->Used == false )
{
// We found a spot
printf("Block found!\n");
// Set the spot to in-use
current->Used = false;
current->Used = true;
// split the block
printf("Split block.\n");
uint32_t oldSize = current->Size;
current->Size = size;
heap_block* new_block = current + sizeof(heap_block) + current->Size;
new_block->Size = oldSize - ( sizeof(heap_block) + size);
new_block->Used = false;
// return the free address
// NOTE: added an offset from the initial address to accomodate for
// meta-data.
@ -36,6 +50,7 @@ void* malloc(size_t size)
// probably ask the VMM for more
// TODO: ask for more memory | Extend kernel heap
printf("ERROR: OUT OF HEAP MEMORY CONDITION IS NOT IMPLEMENTED. HEAP NEEDS TO BE EXTENDED!\n");
}
void free(void* addr)
@ -48,6 +63,26 @@ void free(void* addr)
void initHeap()
{
// NOTE: What to do now??
// put the start of our kernel heap 1 page after the kernel_end address
// Lets calculate the address
printf("FIND SUITABLE HEAP_ADDRESS\n");
uint32_t alligned_k_end = (uint32_t) &kernel_end + ((uint32_t)&kernel_end % BLOCK_SIZE == 0 ? 4096 : 0);
uint32_t HEAP_ADDRESS = (uint32_t) alligned_k_end + 4096;
printf("HEAP_ADDRESS: 0x%x\n", HEAP_ADDRESS);
// NOTE: we can't check if the mapping has failed or not here!
AllocatePage(HEAP_ADDRESS);
start = (heap_block*) HEAP_ADDRESS;
heap_size = 4096;
printf("Clear heap\n");
// Clear the heap
printf("set at 0x%x %d bytes to zero\n", start , heap_size);
memset((void*)start, 0x00, heap_size /4);
printf("Init first heap block\n");
// initialzie
start->Size = heap_size - sizeof(heap_block);
start->Used = false;
}

3
source/kernel/memory/PhysicalMemoryManager.cpp
View File

@ -1,5 +1,4 @@
#include "./PhysicalMemoryManager.h"
#define BLOCK_SIZE 4092
#define IS_ALIGNED(addr, align) !((addr) & ~((align) - 1))
#define ALIGN(addr, align) (((addr) & ~((align) - 1 )) + (align))
@ -28,7 +27,7 @@ void SetupPhysicalMemoryManager(uint32_t mapAddress, uint32_t memorySize )
printf("Bitmap size: %d bytes\n",bitmap_size);
// Set blocks used to zero
used_blocks = 0;
used_blocks = max_blocks;
// set the address of the memory bitmap
memoryBitMap = (uint32_t*) mapAddress;

1
source/kernel/memory/PhysicalMemoryManager.h
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@ -5,6 +5,7 @@
#include "../lib/mem.h"
#include "../bitmap.h"
#define BLOCK_SIZE 4092
void SetupPhysicalMemoryManager(uint32_t mapAddress, uint32_t memorySize);

32
source/kernel/memory/VirtualMemoryManager.cpp
View File

@ -1,9 +1,16 @@
#include "VirtualMemoryManager.h"
#define ALIGN(addr, align) (((addr) & ~((align) - 1 )) + (align))
extern uint32_t boot_page_directory[1024] ;
extern uint32_t boot_page_table[1024];
void flush_cr3(){
asm volatile("movl %cr3, %ecx;"
"movl %ecx, %cr3");
}
void AllocatePage(uint32_t vaddr)
{
uint32_t page_aligned_address = ALIGN(vaddr, 4096);
@ -15,23 +22,31 @@ void AllocatePage(uint32_t vaddr)
printf("Allocation happening at PDE: %d PTE: %d\n", PageDirectoryEntryIndex, PageTableEntryIndex);
// check if the page directory entry is marked as present
if (boot_page_directory[PageDirectoryEntryIndex] & 0x1 ) {
uint32_t* page_table = (uint32_t*)((boot_page_directory[PageDirectoryEntryIndex]) & 0xFFFFE000 + 0xC0000000);
if (boot_page_directory[PageDirectoryEntryIndex] & 0x1 )
{
printf("Directory entry is marked as present\n");
uint32_t* page_table = (uint32_t*)((boot_page_directory[PageDirectoryEntryIndex]) & 0xFFFFE000) ;
page_table = (uint32_t*) ((uint32_t)page_table + 0xC0000000); // Add kernel offset
printf("Page table address: 0x%x\n", (uint32_t)page_table);
// check if the page table entry is marked as present
if ( page_table[PageTableEntryIndex] & 0x1 )
{
printf("page already present!\n");
return;
} else{
printf("Mapping a physical page.\n");
// Map the entry to a physical page
page_table[PageTableEntryIndex] = (uint32_t)(allocate_block() + 0x3);
} else{
// mark page as present
page_table[PageTableEntryIndex] = 0x3;
flush_cr3();
}
} else {
printf("Mapping a new page directory entry with a page table\n");
// mark the page table as present and allocate a physical block for it
boot_page_directory[PageDirectoryEntryIndex] = (uint32_t)(allocate_block() + 0x3);
flush_cr3();
}
@ -56,7 +71,8 @@ void FreePage(uint32_t vaddr )
}
void Map ( uint32_t vaddr, uint32_t paddr)
void Immediate_Map ( uint32_t vaddr, uint32_t paddr)
{
uint32_t page_aligned_address = ALIGN(vaddr, 4096);
@ -66,7 +82,7 @@ void Map ( uint32_t vaddr, uint32_t paddr)
}
void Unmap(uint32_t vaddr)
void Immediate_Unmap(uint32_t vaddr)
{
// NOTE: I will implement lazy unmapping for now
uint32_t page_aligned_address = ALIGN(vaddr, 4096);

12
source/kernel/memory/VirtualMemoryManager.h
View File

@ -1,10 +1,16 @@
#pragma once
#include "PhysicalMemoryManager.h"
#include "../terminal/kterm.h"
#include "../cpu.h"
#include "PhysicalMemoryManager.h"
void SetupVMM();
void AllocatePage(uint32_t v_addr );
void FreePage(uint32_t v_addr);
void Map(uint32_t p_addr, uint32_t v_addr);
void Unmap (uint32_t v_addr);
void Immediate_Map(uint32_t p_addr, uint32_t v_addr);
void Immediate_Unmap (uint32_t v_addr);
// void Demand_map(uint32_t p_addr, uint32_t v_addr);
// void Demand_Unmap (uint32_t v_addr);

11
source/kernel/prekernel/bootstructure.h
View File

@ -11,13 +11,7 @@ extern "C" const uint32_t kernel_end;
#define IS_NVS_MEMORY(MEM_TYPE) MEM_TYPE & 0x8
#define IS_BADRAM_MEMORY(MEM_TYPE) MEM_TYPE & 0x10
struct MemoryInfoBlock {
uint32_t Base_addr ;
uint32_t Memory_Size;
MemoryInfoBlock* next;
uint8_t type;
};
struct BootInfoBlock {
bool MapIsInvalid;
uint32_t bootDeviceID ;
@ -33,9 +27,4 @@ struct BootInfoBlock {
bool EnabledVBE;
bool PhysicalMemoryMapAvailable;
MemoryInfoBlock* MemoryMap;
uint32_t map_size;
uint32_t MemorySize ;
};

17
source/kernel/serial.h
View File

@ -56,20 +56,3 @@ void print_serial(const char* string ){
}
}
void test_serial(){
/** Serial test **/
kterm_writestring("Writing to COM1 serial port:");
init_serial();
write_serial('A');
write_serial('B');
write_serial('C');
write_serial('D');
write_serial('E');
char Character_received = read_serial();
kterm_writestring("\n");
kterm_writestring("received from COM 1: \n");
kterm_put(Character_received);
kterm_writestring("\n");
}