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KERNEL: Pre-kernel sets up the physical memory manager.

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* BUG: allocated blocks is possibly incorrect!
* prekernel no longer gets compiled as being in physical memory
This commit is contained in:
Nigel Barink 2022-09-03 01:00:17 +02:00
parent 01fcb0aa15
commit 656ca0baa8
9 changed files with 193 additions and 237 deletions
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2
source/kernel/bitmap.h
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@ -2,7 +2,6 @@
#include <stddef.h>
#include <stdint.h>
inline void bitmap_set( uint32_t* map , int index )
{
map[index/32] |= (1 << (index % 32));
@ -24,7 +23,6 @@ inline uint32_t bitmap_first_unset( uint32_t* map , int map_size)
for(int j = 0 ; j < 32 ; j++){
if ( (map[i] & (0x00000001 << j)) > 0)
{
printf("Found bit: byte 0x%x , bit 0x%x\n", i , j);
return (i*32)+j;
}
}

19
source/kernel/boot/boot.s
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@ -27,17 +27,10 @@ multiboot_page_table:
# Entry point
.section .multiboot.text, "a"
.global _start
.globl _start
.type _start, @function
_start:
/* push the pointer to the Multiboot information structure*/
pushl %ebx
/* push the magic value */
pushl %eax
call prekernelSetup
# Get physical address of the boot_page_table
movl $(boot_page_table - 0xC0000000), %edi
# Map address 0
@ -82,8 +75,15 @@ _start:
4:
# At this point, paging is fully set up and enabled
isPaging:
/* push the pointer to the Multiboot information structure*/
pushl %ebx
/* push the magic value */
pushl %eax
call prekernelSetup
# Unmap the identity mapping as it is now unnecessary
//movl $0, boot_page_directory + 0
movl $0, boot_page_directory + 0
# Reload cr3 to force tlb flush
movl %cr3, %ecx
@ -97,6 +97,7 @@ isPaging:
pushl $0
popf
call early_main
cli

37
source/kernel/kernel.cpp
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@ -39,13 +39,17 @@ extern "C" void early_main()
{
init_serial();
print_serial("Hello Higher half kernel!\n");
kterm_init();
printf("Allocated blocks: %d \n", GetUsedBlocks());
initGDT();
init_idt();
// Enable interrupts
asm volatile("STI");
ProcessBootInfo();
initHeap();
@ -75,33 +79,4 @@ extern "C" void early_main()
kernel_main();
}
void ProcessBootInfo(){
uint32_t BootInfoStruct = BootInfoBlock_pptr + 0xC0000000;
BootInfoBlock* BootInfo = (BootInfoBlock*) ( BootInfoBlock_pptr + 0xC0000000 );
if( BootInfo->ValidELFHeader )
{
// NOTE: Do something with it.. (Store it , process it etc...)
}
if(BootInfo->EnabledVBE)
{
// NOTE: Do something with it.. (Store it , process it etc...)
}
if(BootInfo->ValidSymbolTable)
{
// NOTE: Do something with it.. (Store it , process it etc...)
// printf("- Valid Symbol Table available at 0x%x.\n Tab Size: %d, str Size: %d\n", BootInfo->SymbolTableAddr, BootInfo->SymbolTabSize, BootInfo->SymbolStrSize);
}
if(BootInfo->PhysicalMemoryMapAvailable)
{
SetupPhysicalMemoryManager(BootInfo);
}
}
}

6
source/kernel/linker.ld
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@ -8,20 +8,16 @@ SECTIONS
_kernel_start = .;
kernel_begin = .; /* For legacy reasons */
.multiboot.data : {
*(.multiboot.data)
}
.multiboot.text : {
*(multiboot.text)
*prekernel.o(.text)
}
. += 0xC0000000; /* Addresses in the following code need to be above the 3Gb mark */
.text ALIGN (4K) : AT (ADDR (.text) - 0xC0000000)
{
*(.text)

98
source/kernel/memory/PhysicalMemoryManager.cpp
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@ -1,66 +1,46 @@
#include "./PhysicalMemoryManager.h"
#define BLOCK_SIZE 4092
#define IS_ALIGNED(addr, align) !((addr) & ~((align) - 1))
#define ALIGN(addr, align) (((addr) & ~((align) - 1 )) + (align))
const uint32_t KERNEL_OFFSET = 0xC0000000;
extern uint32_t* boot_page_directory;
extern uint32_t* boot_page_table;
extern uint32_t* multiboot_page_table;
PhysicalMemoryManagerInfoBlock* PMMInfoBlock;
uint32_t* memoryBitMap;
uint32_t pmmap_size;
uint32_t max_blocks;
int used_blocks;
void SetupPhysicalMemoryManager( BootInfoBlock* Bootinfo)
void SetupPhysicalMemoryManager(uint32_t mapAddress, uint32_t memorySize )
{
// NOTE: We should move our bitmap to just after the end of our kernel instead
PMMInfoBlock = (PhysicalMemoryManagerInfoBlock*) ( ((uint32_t)MemoryMapHeap_pptr + 80 ) + KERNEL_OFFSET );
/*
/*
Every byte contains 8 pages
A page is 4096 kib
Every block (1 bit) represent an page
*/
// Calculate the maximum number of blocks
int maximum_blocks = (uint32_t)Bootinfo->MemorySize / BLOCK_SIZE / 8;
PMMInfoBlock->max_blocks = maximum_blocks;
PMMInfoBlock->used_blocks = 0;
// Set the maximum number of blocks
max_blocks = (uint32_t)memorySize / BLOCK_SIZE ;
printf("Max Blocks: %d\n", max_blocks);
// put the map after the gdt
PMMInfoBlock->memoryBitMap = (uint32_t*) ( 0xC010b100) ;
// Set size of the bitmap
uint32_t bitmap_size = max_blocks / 32;
printf("Bitmap size: %d bytes\n",bitmap_size);
// Set blocks used to zero
used_blocks = 0;
//Size of memory map
uint32_t memMap_size = PMMInfoBlock->max_blocks / 8;
// set the address of the memory bitmap
memoryBitMap = (uint32_t*) mapAddress;
// Set all places in memory as free
memset(PMMInfoBlock->memoryBitMap, 0xFF, memMap_size );
MemoryInfoBlock* currentBlock = (MemoryInfoBlock*) ((uint32_t)Bootinfo->MemoryMap + 0xC0000000) ;
printf( "Starting address: 0x%x\n", currentBlock);
while( (uint32_t)currentBlock->next != 0x0 )
{
if(IS_AVAILABLE_MEM(currentBlock->type)){
printf("skip!\n");
}
else{
printf("allocate region 0x%x of size %d bytes\n", currentBlock->Base_addr, currentBlock->Memory_Size);
// allocate_region( currentBlock->Base_addr, currentBlock->Memory_Size); // allocate region causes #PF Exception
}
currentBlock = (MemoryInfoBlock*) ((uint32_t)currentBlock->next + 0xC0000000 );
}
uint32_t kernel_size = ((uint32_t)&kernel_end - (uint32_t)&kernel_begin ) - KERNEL_OFFSET;
printf("kernel size in memory: 0x%x\n", kernel_size);
allocate_region((uint32_t)&kernel_begin, kernel_size);
printf("allocate BIOS region\n");
allocate_region (0x0000000, 0x00100000);
memset(memoryBitMap, 0xFFFFFFFF, max_blocks / 32 );
}
// NOTE: This can only give blocks of 4kb at a time!
// We might at some point want to allocate multiple blocks at once.
void* allocate_block() {
uint8_t blocks_available = PMMInfoBlock->max_blocks - PMMInfoBlock->used_blocks;
uint8_t blocks_available = max_blocks - used_blocks;
// Are there any blocks available?
if( blocks_available <= 0)
{
@ -69,7 +49,7 @@ void* allocate_block() {
}
// Find 1 free block somewhere
int free_block_index = bitmap_first_unset(PMMInfoBlock->memoryBitMap, PMMInfoBlock->max_blocks / 8 );
int free_block_index = bitmap_first_unset(memoryBitMap, max_blocks / 8 );
if(free_block_index == -1)
{
@ -82,10 +62,10 @@ void* allocate_block() {
printf("Somethings wrong!!!\n");
// Set the block to be used!
bitmap_unset(PMMInfoBlock->memoryBitMap, free_block_index);
bitmap_unset(memoryBitMap, free_block_index);
// Increase the used_block count!
PMMInfoBlock->used_blocks++;
printf("used blocks: 0x%x\n", PMMInfoBlock->used_blocks);
used_blocks++;
printf("used blocks: 0x%x\n", used_blocks);
// return the pointer to the physical address
return (void*) (BLOCK_SIZE * free_block_index);
}
@ -99,9 +79,9 @@ void free_block(void* p) {
int index = ((uint32_t) p) / BLOCK_SIZE;
// set the block to be free
bitmap_set(PMMInfoBlock->memoryBitMap, index);
PMMInfoBlock->used_blocks--;
printf("used blocks: 0x%x, after free\n", PMMInfoBlock->used_blocks);
bitmap_set(memoryBitMap, index);
used_blocks--;
printf("used blocks: 0x%x, after free\n", used_blocks);
}
@ -111,28 +91,26 @@ void allocate_region(uint32_t startAddress, uint32_t size) {
int NumberOfBlocksToAllocate = ( size / 1024) / 4 / 8 + 1;
int startBlock = (startAddress / 1024) / 4 / 8 ;
for( int i = 0; i < NumberOfBlocksToAllocate; i++)
{
bitmap_unset(PMMInfoBlock->memoryBitMap, startBlock+ i);
PMMInfoBlock->used_blocks++;
bitmap_unset(memoryBitMap, startBlock + i);// allocate region causes #PF Exception
used_blocks++;
}
}
void deallocate_region(uint32_t StartAddress , uint32_t size ) {
// reverse of what happened in allocate_region
int NumberOfBlocks = (size / 1024) / 4 / 8 + 1;
int startBlock = (StartAddress / 1024) / 4 / 8;
for(int i = 0; i < NumberOfBlocks; i++)
{
bitmap_set(PMMInfoBlock->memoryBitMap, startBlock + i);
PMMInfoBlock->used_blocks --;
bitmap_set(memoryBitMap, startBlock + i);
used_blocks --;
}
}
int GetUsedBlocks (){
return used_blocks;
}

22
source/kernel/memory/PhysicalMemoryManager.h
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@ -5,22 +5,14 @@
#include "../lib/mem.h"
#include "../bitmap.h"
// Asumming i386 for now!
#define BLOCK_SIZE 4092
#define IS_ALIGNED(addr, align) !((addr) & ~((align) - 1))
#define ALIGN(addr, align) (((addr) & ~((align) - 1 )) + (align))
struct PhysicalMemoryManagerInfoBlock
{
uint32_t* memoryBitMap;
uint32_t pmmap_size;
uint32_t max_blocks;
int used_blocks;
};
void SetupPhysicalMemoryManager(uint32_t mapAddress, uint32_t memorySize);
void SetupPhysicalMemoryManager(BootInfoBlock* memory);
void free_block(void* ptr);
void* allocate_block();
void allocate_region(uint32_t, uint32_t);
void deallocate_region(uint32_t , uint32_t );
void free_block(void* ptr);
void allocate_region(uint32_t address, uint32_t size);
void deallocate_region(uint32_t address, uint32_t size);
int GetUsedBlocks();

2
source/kernel/memory/VirtualMemoryManager.cpp
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@ -1,5 +1,5 @@
#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];

5
source/kernel/prekernel/bootstructure.h
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@ -39,8 +39,3 @@ struct BootInfoBlock {
uint32_t MemorySize ;
};
const uint32_t pke = ((uint32_t)&kernel_end) - 0xC0000000;
const uint32_t BootInfoBlock_pptr = pke + 1000 - sizeof(BootInfoBlock);
const uint32_t MemoryMapHeap_pptr = pke + 0x1;

239
source/kernel/prekernel/prekernel.cpp
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@ -1,119 +1,140 @@
#include <stdint.h>
#include <stddef.h>
#include "multiboot.h"
#include "bootstructure.h"
#include "../memory/PhysicalMemoryManager.h"
#define CHECK_FLAG(flags, bit) ((flags) & (1 <<(bit)))
#define VADDR_TO_PADDR(vaddr) (vaddr - 0xC0000000)
#define PADDR_TO_VADDR(paddr) (paddr + 0xC0000000)
extern "C" void prekernelSetup ( unsigned long magic, multiboot_info_t* mbi) {
// Create the bootInfoBlock at its location
BootInfoBlock* BIB = (BootInfoBlock*) BootInfoBlock_pptr;
extern "C" void prekernelSetup ( unsigned long magic, multiboot_info_t* mbi)
{
/*
* Check Multiboot magic number
*/
if (magic != MULTIBOOT_BOOTLOADER_MAGIC)
{
BIB->MapIsInvalid = true;
// crash
return;
} else{
BIB->MapIsInvalid = false;
}
/* is boot device valid ? */
if (CHECK_FLAG (mbi->flags, 1))
{
BIB->bootDeviceID = mbi->boot_device;
} else{
BIB->bootDeviceID = 0x11111111;
}
/* Are mods_* valid? */
if(CHECK_FLAG ( mbi->flags, 3)){
multiboot_module_t *mod;
uint32_t i;
BIB->GrubModuleCount = mbi->mods_count;
for(i = 0, mod = (multiboot_module_t *) mbi->mods_addr; i < mbi->mods_count; i++ , mod++){
}
}
/* Is the symbol table of a.out valid? */
if (CHECK_FLAG(mbi->flags, 4))
{
BIB->ValidSymbolTable = true;
multiboot_aout_symbol_table_t *multiboot_aout_sym = &(mbi->u.aout_sym);
} else{
BIB->ValidSymbolTable = false;
}
/* Is the section header table of ELF valid? */
if (CHECK_FLAG(mbi->flags, 5))
{
BIB->ValidELFHeader = true;
multiboot_elf_section_header_table_t *multiboot_elf_sec = &(mbi->u.elf_sec);
}else{
BIB->ValidELFHeader = false;
}
/*
If we got a memory map from our bootloader we
should be parsing it to find out the memory regions available.
*/
if (CHECK_FLAG(mbi->flags, 6))
{
BIB->PhysicalMemoryMapAvailable = true;
BIB->MemoryMap = (MemoryInfoBlock*) MemoryMapHeap_pptr;
multiboot_memory_map_t *mmap = (multiboot_memory_map_t*) (mbi->mmap_addr) ;
auto MemoryMapEnd = mbi->mmap_addr + mbi->mmap_length;
auto CurrentInfoBlock = BIB->MemoryMap;
uint32_t RAM_size = 0;
while((unsigned long) mmap < MemoryMapEnd){
BIB->map_size += sizeof(MemoryInfoBlock);
CurrentInfoBlock->Base_addr = mmap->addr;
CurrentInfoBlock->Memory_Size = mmap->len;
if(mmap->type == MULTIBOOT_MEMORY_AVAILABLE)
CurrentInfoBlock->type |= 0x1;
RAM_size += mmap->len;
if(mmap->type == MULTIBOOT_MEMORY_ACPI_RECLAIMABLE)
CurrentInfoBlock->type |= 0x2;
if(mmap->type == MULTIBOOT_MEMORY_RESERVED)
CurrentInfoBlock->type |= 0x4;
if(mmap->type == MULTIBOOT_MEMORY_NVS)
CurrentInfoBlock->type |= 0x8;
if(mmap->type == MULTIBOOT_MEMORY_BADRAM)
CurrentInfoBlock->type |= 0x10;
// continue to the next block
mmap = (multiboot_memory_map_t *) ((unsigned long) mmap + mmap->size + sizeof(mmap->size));
CurrentInfoBlock->next = (MemoryInfoBlock*) CurrentInfoBlock + 16;
CurrentInfoBlock = CurrentInfoBlock->next;
/*
* Check Multiboot magic number
*/
if (magic != MULTIBOOT_BOOTLOADER_MAGIC)
{
// PANIC!!
return;
}
CurrentInfoBlock->next = (MemoryInfoBlock*) 0x0;
BIB->MemorySize = RAM_size;
} else
{
BIB->PhysicalMemoryMapAvailable = false;
}
/* Draw diagonal blue line */
if (CHECK_FLAG (mbi->flags, 12)){
BIB->EnabledVBE = true;
} else{
BIB->EnabledVBE;
}
mbi = PADDR_TO_VADDR(mbi);
// Setup the physical memory manager immmediatly
// Doing so saves the complications of doing it later when
// paging is enabled
/*
If we got a memory map from our bootloader we
should be parsing it to find out the memory regions available.
*/
if (CHECK_FLAG(mbi->flags, 6))
{
// Calculate total memory size
uint32_t RAM_size = 0;
for(
multiboot_memory_map_t* mmap = (multiboot_memory_map_t*) mbi->mmap_addr;
(unsigned long)mmap < mbi->mmap_addr + mbi->mmap_length;
mmap += mmap->size +sizeof(mmap->size)
){
RAM_size += mmap->len;
}
// Call SetupPhysicalMemoryManager at its physical address
SetupPhysicalMemoryManager ( (uint32_t)VADDR_TO_PADDR(&kernel_end), RAM_size);
for(
multiboot_memory_map_t* mmap = (multiboot_memory_map_t*) mbi->mmap_addr;
(unsigned long)mmap < mbi->mmap_addr + mbi->mmap_length;
mmap += mmap->size +sizeof(mmap->size)
){
if(mmap->type == MULTIBOOT_MEMORY_AVAILABLE)
deallocate_region(mmap->addr, mmap->len);
if(mmap->type == MULTIBOOT_MEMORY_ACPI_RECLAIMABLE)
allocate_region(mmap->addr, mmap->len);
if(mmap->type == MULTIBOOT_MEMORY_RESERVED)
allocate_region(mmap->addr, mmap->len);
if(mmap->type == MULTIBOOT_MEMORY_NVS)
allocate_region(mmap->addr, mmap->len);
if(mmap->type == MULTIBOOT_MEMORY_BADRAM)
allocate_region(mmap->addr, mmap->len);
}
// Allocate the kernel
allocate_region( (uint32_t)&kernel_begin, ( (uint32_t)&kernel_end - (uint32_t)&kernel_begin)- 0xC0000000 );
// Allocate the memory region below 1MB
allocate_region(0x0000000, 0x00100000);
}
else
{
// We didn't get a memory map from our bootloader.
// PANIC!!!!
return;
}
// allocate a full block for the other boot info!
BootInfoBlock* BIB = (BootInfoBlock*) allocate_block();
/* is boot device valid ? */
if (CHECK_FLAG (mbi->flags, 1))
{
BIB->bootDeviceID = mbi->boot_device;
} else{
BIB->bootDeviceID = 0x11111111;
}
/* Are mods_* valid? */
if(CHECK_FLAG ( mbi->flags, 3)){
multiboot_module_t *mod;
uint32_t i;
BIB->GrubModuleCount = mbi->mods_count;
for(i = 0, mod = (multiboot_module_t *) mbi->mods_addr; i < mbi->mods_count; i++ , mod++){
}
}
/* Is the symbol table of a.out valid? */
if (CHECK_FLAG(mbi->flags, 4))
{
// NOTE: Do something with it.. (Store it , process it etc...)
// printf("- Valid Symbol Table available at 0x%x.\n Tab Size: %d, str Size: %d\n", BootInfo->SymbolTableAddr, BootInfo->SymbolTabSize, BootInfo->SymbolStrSize);
BIB->ValidSymbolTable = true;
multiboot_aout_symbol_table_t *multiboot_aout_sym = &(mbi->u.aout_sym);
} else{
BIB->ValidSymbolTable = false;
}
/* Is the section header table of ELF valid? */
if (CHECK_FLAG(mbi->flags, 5))
{
// NOTE: Do something with it.. (Store it , process it etc...)
BIB->ValidELFHeader = true;
multiboot_elf_section_header_table_t *multiboot_elf_sec = &(mbi->u.elf_sec);
}else{
BIB->ValidELFHeader = false;
}
/* Draw diagonal blue line */
if (CHECK_FLAG (mbi->flags, 12)){
BIB->EnabledVBE = true;
// NOTE: Do something with it.. (Store it , process it etc...)
} else{
BIB->EnabledVBE;
}
}