151 lines
3.0 KiB
C
151 lines
3.0 KiB
C
#include "../libc/stdint.h"
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#include "paging.h"
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#include "../libc/stdio.h"
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#include "system.h"
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#include "kheap.h"
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uint32_t *frames;
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uint32_t nframes;
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extern uint32_t placement_address;
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#define INDEX_FROM_BIT(a) (a/(8*4))
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#define OFFSET_FROM_BIT(a) (a%(8*4))
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static void set_frame(uint32_t frame_addr)
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{
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uint32_t frame = frame_addr/0x1000;
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uint32_t idx = INDEX_FROM_BIT(frame);
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uint32_t off = OFFSET_FROM_BIT(frame);
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frames[idx] |= (0x1 << off);
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}
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static void clear_frame(uint32_t frame_addr)
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{
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uint32_t frame = frame_addr/0x1000;
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uint32_t idx = INDEX_FROM_BIT(frame);
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uint32_t off = OFFSET_FROM_BIT(frame);
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frames[idx] &= ~(0x1 << off);
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}
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/*
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static uint32_t test_frame(uint32_t frame_addr)
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{
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uint32_t frame = frame_addr/0x1000;
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uint32_t idx = INDEX_FROM_BIT(frame);
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uint32_t off = OFFSET_FROM_BIT(frame);
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return (frames[idx] & (0x1 << off));
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}
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*/
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static uint32_t first_frame()
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{
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uint32_t i, j;
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for (i=0; i<INDEX_FROM_BIT(nframes); i++)
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{
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if (frames[i] != 0xFFFFFFFF)
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{
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for (j=0; j<32; j++)
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{
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uint32_t toTest = 0x1 << j;
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if (!(frames[i]&toTest))
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{
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return i*4*8+j;
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}
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}
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}
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}
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return 0;
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}
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void alloc_frame(page_t *page, int is_kernel, int is_writeable)
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{
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if (page->frame != 0)
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{
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return;
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} else {
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uint32_t idx = first_frame();
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if (idx == (uint32_t)-1)
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{
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panic();
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}
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set_frame(idx*0x1000);
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page->present = 1;
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page->rw = (is_writeable)?1:0;
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page->user = (is_kernel)?0:1;
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page->frame = idx;
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}
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}
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void free_frame(page_t *page)
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{
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uint32_t frame;
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if (!(frame=page->frame))
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{
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return;
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} else {
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clear_frame(frame);
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page->frame = 0x0;
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}
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}
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void init_paging()
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{
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uint32_t mem_end_page = 0x10000000;
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nframes = mem_end_page / 0x1000;
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frames = (uint32_t*)kmalloc(INDEX_FROM_BIT(nframes));
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memset(frames, 0, INDEX_FROM_BIT(nframes));
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page_directory_t* kernel_directory = (page_directory_t*)kmalloc_a(sizeof(page_directory_t));
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memset(kernel_directory, 0, sizeof(page_directory_t));
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//page_directory_t* current_directory = kernel_directory;
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unsigned int i = 0;
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while (i < placement_address)
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{
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alloc_frame(get_page(i, 1, kernel_directory), 0, 0);
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i += 0x1000;
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}
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irq_install_handler(14, page_fault);
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switch_page_directory(kernel_directory);
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}
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void switch_page_directory(page_directory_t *dir)
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{
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//page_directory_t* current_directory = dir;
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asm volatile("mov %0, %%cr3":: "r"(&dir->tablesPhysical));
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uint32_t cr0;
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asm volatile("mov %%cr0, %0": "=r"(cr0));
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cr0 |= 0x80000000;
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asm volatile("mov %0, %%cr0":: "r"(cr0));
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}
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page_t *get_page(uint32_t address, int make, page_directory_t *dir)
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{
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address /= 0x1000;
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uint32_t table_idx = address / 1024;
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if (dir->tables[table_idx])
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{
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return &dir->tables[table_idx]->pages[address%1024];
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} else if (make)
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{
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uint32_t tmp;
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dir->tables[table_idx] = (page_table_t*)kmalloc_ap(sizeof(page_table_t), &tmp);
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memset(dir->tables[table_idx], 0, 0x1000);
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dir->tablesPhysical[table_idx] = tmp | 0x7;
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return &dir->tables[table_idx]->pages[address%1024];
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} else {
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return 0;
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}
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return 0;
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}
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void page_fault()
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{
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puts("Page fault");
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panic();
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}
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