Add: paging & test

src/kernel/paging.c

@@ -0,0 +1,150 @@
+#include "../libc/stdint.h"
+#include "paging.h"
+#include "../libc/stdio.h"
+#include "system.h"
+#include "kheap.h"
+
+
+uint32_t *frames;
+uint32_t nframes;
+
+extern uint32_t placement_address;
+
+#define INDEX_FROM_BIT(a) (a/(8*4))
+#define OFFSET_FROM_BIT(a) (a%(8*4))
+
+static void set_frame(uint32_t frame_addr)
+{
+	uint32_t frame = frame_addr/0x1000;
+	uint32_t idx = INDEX_FROM_BIT(frame);
+	uint32_t off = OFFSET_FROM_BIT(frame);
+	frames[idx] |= (0x1 << off);
+}
+
+static void clear_frame(uint32_t frame_addr)
+{
+	uint32_t frame = frame_addr/0x1000;
+	uint32_t idx = INDEX_FROM_BIT(frame);
+	uint32_t off = OFFSET_FROM_BIT(frame);
+	frames[idx] &= ~(0x1 << off);
+}
+
+/*
+static uint32_t test_frame(uint32_t frame_addr)
+{
+   	uint32_t frame = frame_addr/0x1000;
+   	uint32_t idx = INDEX_FROM_BIT(frame);
+   	uint32_t off = OFFSET_FROM_BIT(frame);
+   	return (frames[idx] & (0x1 << off));
+}
+*/
+
+static uint32_t first_frame()
+{
+	uint32_t i, j;
+	for (i=0; i<INDEX_FROM_BIT(nframes); i++)
+	{
+		if (frames[i] != 0xFFFFFFFF)
+		{
+			for (j=0; j<32; j++)
+			{
+				uint32_t toTest = 0x1 << j;
+				if (!(frames[i]&toTest))
+				{
+					return i*4*8+j;
+				}
+			}
+		}
+	}
+	return 0;
+}
+
+void alloc_frame(page_t *page, int is_kernel, int is_writeable)
+{
+	if (page->frame != 0)
+	{
+		return;
+	} else {
+		uint32_t idx = first_frame();
+		if (idx == (uint32_t)-1)
+		{
+			panic();
+		}
+		set_frame(idx*0x1000);
+		page->present = 1;
+		page->rw = (is_writeable)?1:0;
+		page->user = (is_kernel)?0:1;
+		page->frame = idx;
+	}
+}
+
+void free_frame(page_t *page)
+{
+	uint32_t frame;
+	if (!(frame=page->frame))
+	{
+		return;
+	} else {
+		clear_frame(frame);
+		page->frame = 0x0;
+	}
+}
+
+void init_paging()
+{
+	uint32_t mem_end_page = 0x10000000;
+	nframes = mem_end_page / 0x1000;
+	frames = (uint32_t*)kmalloc(INDEX_FROM_BIT(nframes));
+	memset(frames, 0, INDEX_FROM_BIT(nframes));
+
+	page_directory_t* kernel_directory = (page_directory_t*)kmalloc_a(sizeof(page_directory_t));
+	memset(kernel_directory, 0, sizeof(page_directory_t));
+	//page_directory_t* current_directory = kernel_directory;
+
+	unsigned int i = 0;
+	while (i < placement_address)
+	{
+		alloc_frame(get_page(i, 1, kernel_directory), 0, 0);
+		i += 0x1000;
+	}
+
+	irq_install_handler(14, page_fault);
+
+	switch_page_directory(kernel_directory);	
+}
+
+void switch_page_directory(page_directory_t *dir)
+{
+	//page_directory_t* current_directory = dir;
+	asm volatile("mov %0, %%cr3":: "r"(&dir->tablesPhysical));
+	uint32_t cr0;
+	asm volatile("mov %%cr0, %0": "=r"(cr0));
+	cr0 |= 0x80000000;
+	asm volatile("mov %0, %%cr0":: "r"(cr0));
+}
+
+page_t *get_page(uint32_t address, int make, page_directory_t *dir)
+{
+	address /= 0x1000;
+	uint32_t table_idx = address / 1024;
+	if (dir->tables[table_idx])
+	{
+		return &dir->tables[table_idx]->pages[address%1024];
+	} else if (make)
+	{
+		uint32_t tmp;
+		dir->tables[table_idx] = (page_table_t*)kmalloc_ap(sizeof(page_table_t), &tmp);
+		memset(dir->tables[table_idx], 0, 0x1000);
+		dir->tablesPhysical[table_idx] = tmp | 0x7;
+		return &dir->tables[table_idx]->pages[address%1024];
+	} else {
+		return 0;
+	}
+	return 0;
+}
+
+void page_fault()
+{
+	puts("Page fault");
+	panic();
+}