Mercurial > lcfOS
view cos/kernel/mm.c @ 180:25a0753da4cf
Re-organized files
author | Windel Bouwman |
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date | Thu, 09 May 2013 17:35:19 +0200 |
parents | 35cc54e078dd |
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/* Memory manager functions, * * Uses a bitmap to keep track of 4k pages that are in use. * * */ #include "kernel.h" #define HEAP_START 0xC000000000000000 #define HEAP_INITIAL_SIZE 0x100000 // Bitmap that keeps track of all the 4 kB memory pages in the system: static uint64_t *frames = 0; static uint64_t nframes = 0; memmap_t* kernel_map = 0; // kernel memory mapping // TODO: determine if this is required. memmap_t* current_map = 0; // The currently active memory mapping heap_t* kernel_heap = 0; static void set_frame(uint64_t frame) { uint64_t idx = frame / 64; uint64_t off = frame % 64; frames[idx] |= (0x1 << off); } static void clear_frame(uint64_t frame) { uint64_t idx = frame / 64; uint64_t off = frame % 64; frames[idx] &= ~(0x1 << off); } uint64_t test_frame(uint64_t frame) { uint64_t idx = frame / 64; uint64_t off = frame % 64; return (frames[idx] & (0x1 << off)); } static uint64_t first_frame() { uint64_t i, j; for (i = 0; i < nframes / 64; i++) { if (frames[i] != 0xFFFFFFFFFFFFFFFF) { for (j = 0; j < 64; j++) { uint64_t dut = 0x1 << j; if ((frames[i] & dut) != dut) { return i*64+j; } } } } // No frame found: return (uint64_t) -1; } void memory_status(void) { // Determine amount of used memory. uint64_t i, j; uint64_t inuse = 0; for (i = 0; i < nframes / 64; i++) { for (j = 0; j < 64; j++) { if ((frames[i] & (1UL<<j)) == (1UL<<j)) { inuse++; } } } printf("Memory: %d, in use: %d\n", nframes/0x100, inuse/0x100); } /* * Initializes the memory manager, allocating a bitmap once. */ void init_memory(uint64_t total_mem_size) { printf("Running with %d MB ram\n", total_mem_size / 1000000); // Memory size is from address 0x100000 total_mem_size += 0x100000; // Only here placement malloc is used! // // Allocate and clear bits to remember which 4KiB-frames are in use: // Calculate number of frames. memory size is indicated from address 0x100000 nframes = (total_mem_size) / 0x1000; // Calculate number of frames int numbytes = ((nframes / 64) + 1) * sizeof(uint64_t); frames = (uint64_t*)kmalloc(numbytes); memset(frames, 0, numbytes); // Create kernel map: kernel_map = (memmap_t*)kmalloc_a(sizeof(memmap_t)); memset(kernel_map, 0, sizeof(memmap_t)); // Identity map lower memory and mark as used by the kernel. // Mark as used by the kernel: uint64_t i; i = 0; while ( i <= placement_address + 0x100000) { page_t *page; page = get_page(i, kernel_map); // Get page for address page->address = i >> 12; // Set the address of this page. page->present = 1; page->rw = 1; page->us = 1; // Make all things accessable for users for now. //page->pwt = 1; // Is this bit required? set_frame(i / 0x1000); i += 0x1000; // Increase a 4 k frame } // Set the created mapping as active: switch_mapping(kernel_map); // Loads cr3 // TODO: set the use of placement malloc to invalid after here. // kernel_heap = create_heap(HEAP_START, HEAP_INITIAL_SIZE); } void alloc_frame(page_t *page) { if (page->address != 0) { return; } uint64_t idx = first_frame(); if (idx == (uint64_t) -1) { panic("No more memory!"); } set_frame(idx); page->present = 1; page->rw = 1; page->us = 0; page->address = idx; // set address in frame number, the byte address is 0x1000 times this value. } void free_frame(page_t *page) { clear_frame(page->address / 0x1000); page->address = 0; page->present = 0; } void switch_mapping(memmap_t* mapping) { current_map = mapping; // Load table address: asm volatile("mov %0, %%cr3" :: "r"(&mapping->table)); // Enable paging (and flush cache): uint64_t cr0; asm volatile("mov %%cr0, %0": "=r"(cr0)); cr0 |= 0x80000000; asm volatile("mov %0, %%cr0":: "r"(cr0)); } /* Get a page for a virtual address, and create other tables if required */ page_t* get_page(uint64_t address, memmap_t *mapping) { // Retrieve the correct PDP (page dir pointer table): uint64_t pml4index = (address >> 39) & 0x1FF; PDPT_t *pdpt = 0; if (mapping->table[pml4index].present == 1) { pdpt = (PDPT_t*)((uint64_t)mapping->table[pml4index].address << 12); } else { // Create new table: printf("Get page for address %x\n", address); // TODO: make sure that this function calls kmalloc instead of placement malloc. pdpt = (PDPT_t*)kmalloc_a(sizeof(PDPT_t)); memset(pdpt, 0, sizeof(PDPT_t)); // TODO: get function like virt2phys or something here uint64_t address = (uint64_t)pdpt; // get the physical address mapping->table[pml4index].address = address >> 12; // shift right mapping->table[pml4index].rw = 1; mapping->table[pml4index].us = 1; mapping->table[pml4index].present = 1; } uint64_t pdptindex = (address >> 30) & 0x1FF; // Retrieve the correct page directory: PD_t *pd = 0; if (pdpt->table[pdptindex].present == 1) { pd = (PD_t*)((uint64_t)pdpt->table[pdptindex].address << 12); } else { // Create a new table: pd = (PD_t*)kmalloc_a(sizeof(PD_t)); memset(pd, 0, sizeof(PD_t)); // Enter table into PDPT: // TODO: make virt2phys function: uint64_t address = (uint64_t)pd; pdpt->table[pdptindex].address = address >> 12; pdpt->table[pdptindex].rw = 1; pdpt->table[pdptindex].us = 1; pdpt->table[pdptindex].present = 1; } // Retrieve the correct page table: uint64_t pdindex = (address >> 21) & 0x1FF; PT_t *pt = 0; if (pd->table[pdindex].present == 1) { pt = (PT_t*)((uint64_t)pd->table[pdindex].address << 12); } else { // Create table: pt = (PT_t*)kmalloc_a(sizeof(PD_t)); memset(pt, 0, sizeof(PT_t)); // Enter PT into PD: uint64_t address = (uint64_t)pt; pd->table[pdindex].address = address >> 12; pd->table[pdindex].rw = 1; pd->table[pdindex].us = 1; pd->table[pdindex].present = 1; } // Finally get the page from the directory: // TODO: convert from physical address to virtual address: uint64_t ptindex = (address >> 12) & 0x1FF; return &pt->table[ptindex]; }