added syscalls & fixed bug in mem manager
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28
gdt.c
Normal file
28
gdt.c
Normal file
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@ -0,0 +1,28 @@
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#include <gdt.h>
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void write_tss(struct tss_entry *tss, struct gdt_entry *gdt, int num, uint16_t ss0, uint32_t esp0) {
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uint32_t base = (uint32_t)tss;
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uint32_t limit = base + sizeof(struct tss_entry);
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gdt[num].base_low = base & 0xFFFF;
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gdt[num].base_middle = (base >> 16) & 0xFF;
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gdt[num].base_high = (base >> 24) & 0xFF;
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gdt[num].limit_low = limit & 0xFFFF;
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gdt[num].granularity = (limit >> 16) & 0x0F;
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gdt[num].granularity |= 0x40;
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gdt[num].access = 0x89;
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memset(&tss, 0, sizeof(struct tss_entry));
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tss->ss0 = ss0;
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tss->esp0 = esp0;
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tss->cs = 0x0b;
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tss->ss = tss->ds = tss->es = tss->fs = tss->gs = 0x13;
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}
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void tss_flush(uint16_t tss_selector) {
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asm volatile (
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"ltr %0"
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: // no output
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: "r" (tss_selector)
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);
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}
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@ -1,34 +0,0 @@
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#ifndef RK_FAT12_H_
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#define RK_FAT12_H_
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#include <stdint.h>
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struct fat12_boot_sector {
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uint8_t jump_boot[3]; // Jump instruction to boot code
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uint8_t oem_name[8]; // OEM name and version
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uint16_t bytes_per_sector; // Bytes per sector
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uint8_t sectors_per_cluster; // Sectors per cluster
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uint16_t reserved_sectors; // Reserved sectors
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uint8_t num_fats; // Number of FATs
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uint16_t root_entry_count; // Number of root directory entries
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uint16_t total_sectors_16; // Total sectors (16-bit)
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uint8_t media; // Media descriptor
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uint16_t fat_size_16; // Sectors per FAT (16-bit)
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uint16_t sectors_per_track; // Sectors per track (for BIOS)
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uint16_t num_heads; // Number of heads (for BIOS)
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uint32_t hidden_sectors; // Hidden sectors
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uint32_t total_sectors_32; // Total sectors (32-bit)
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// Extended Boot Record (EBR) fields
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uint8_t drive_number; // Drive number
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uint8_t reserved1; // Reserved
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uint8_t boot_signature; // Extended boot signature
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uint32_t volume_id; // Volume ID (serial number)
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uint8_t volume_label[11]; // Volume label
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uint8_t file_system_type[8]; // File system type (e.g., "FAT12 ")
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uint8_t boot_code[448]; // Boot code
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uint16_t boot_sector_signature; // Boot sector signature (0xAA55)
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} __attribute__((packed));
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#endif
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@ -2,10 +2,17 @@
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#define RK_GDT_H_
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#include <stdint.h>
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#include <mem.h>
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#define GDT_NULL 0
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#define GDT_KERNEL_CODE 1
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#define GDT_KERNEL_DATA 2
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#define GDT_USER_CODE 3
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#define GDT_USER_DATA 4
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#define RING0 0
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#define RING3 3
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#define GDT_SEGMENT_SELECTOR(i, p) ((i << 3) | p)
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struct gdt_entry {
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@ -47,4 +54,7 @@ struct tss_entry {
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uint16_t iomap_base;
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} __attribute__((packed));
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void write_tss(struct tss_entry *tss, struct gdt_entry *gdt, int num, uint16_t ss0, uint32_t esp0);
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void tss_flush(uint16_t tss_selector);
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#endif
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@ -15,6 +15,12 @@ void mmap_free_block(struct kernel_context *ctx, int block);
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void *mmap_find_first_free_block(struct kernel_context *ctx);
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void *mmap_block_to_physical(struct kernel_context *ctx, int block);
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void *memset(void *s, int c, uint32_t len);
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void memset(void *s, int c, uint32_t len);
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void memcpy(void *dest, void *src, int n);
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typedef struct {
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void *data;
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void *next;
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} linked_mem_t;
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#endif
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171
kmain.c
171
kmain.c
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@ -11,35 +11,51 @@
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#include <ps2.h>
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#include <ide.h>
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#include <mem.h>
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#include <fat12.h>
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struct kernel_context ctx = {0};
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struct idt_entry g_idt[256] = {0};
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struct idtr g_idtr = {0};
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extern uint32_t isr_stub_table[32];
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extern void ps2_isr();
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#define MAGIC_BREAKPOINT __asm__ volatile("xchgw %bx, %bx");
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#define FD_STDOUT 0
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#define FD_STDIN 1
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#define USER_DS 0x23 // User data segment selector
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#define USER_CS 0x1B // User code segment selector
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struct kernel_context ctx = {0};
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struct idt_entry g_idt[256] = {0};
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struct idtr g_idtr = {0};
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extern uint32_t isr_stub_table[32];
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extern void ps2_isr();
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extern struct gdt_entry gdt[6];
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extern void syscall_isr();
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extern void syscall();
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extern void test();
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linked_mem_t stdout = {0};
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linked_mem_t stdin = {0};
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struct tss_entry tss;
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void tss_flush(uint16_t tss_selector) {
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asm volatile (
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"ltr %0"
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: // no output
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: "r" (tss_selector)
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);
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struct stack_frame {
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uint32_t edi, esi, ebp, esp, ebx, edx, ecx, eax;
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};
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void syscall_read(struct stack_frame regs) {
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uint32_t fd = regs.edi;
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char *buf = (char *)regs.esi;
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uint32_t count = regs.edx;
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if (fd == FD_STDOUT) {
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int pages = count / BLOCK_SIZE;
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if (pages == 0) {
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memcpy(buf, stdout.data, count);
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}
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}
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}
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void test() {
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printf("\n\nHello from user mode!\n");
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for (;;) {}
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void syscall_write(struct stack_frame regs) {
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uint32_t fd = regs.edi;
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char *buf = (char *)regs.esi;
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//uint32_t count = regs.edx;
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if (fd == FD_STDOUT) {
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printf("%s", buf);
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}
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}
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void switch_to_user_mode(void *user_stack, void *user_entry) {
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@ -67,25 +83,6 @@ void switch_to_user_mode(void *user_stack, void *user_entry) {
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);
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}
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void write_tss(int num, uint16_t ss0, uint32_t esp0) {
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uint32_t base = (uint32_t)&tss;
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uint32_t limit = base + sizeof(tss);
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gdt[num].base_low = base & 0xFFFF;
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gdt[num].base_middle = (base >> 16) & 0xFF;
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gdt[num].base_high = (base >> 24) & 0xFF;
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gdt[num].limit_low = limit & 0xFFFF;
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gdt[num].granularity = (limit >> 16) & 0x0F;
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gdt[num].granularity |= 0x40;
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gdt[num].access = 0x89;
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memset(&tss, 0, sizeof(tss));
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tss.ss0 = ss0;
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tss.esp0 = esp0;
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tss.cs = 0x0b;
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tss.ss = tss.ds = tss.es = tss.fs = tss.gs = 0x13;
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}
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void kmain(struct multiboot_info *info) {
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clear_screen();
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set_color(VGA_COLOR_CYAN);
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@ -95,22 +92,13 @@ void kmain(struct multiboot_info *info) {
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ctx.multi_mmap = (struct multiboot_mmap_entry *)info->memMapAddress;
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ctx.multi_mmap_size = info->memMapLength / sizeof(struct multiboot_mmap_entry);
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for (uint32_t i = 0; i < ctx.multi_mmap_size; i++) {
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struct multiboot_mmap_entry entry = ctx.multi_mmap[i];
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if (entry.type != MULTIBOOT_MEMORY_AVAILABLE) continue;
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uint32_t len = (uint32_t)(entry.len_low | entry.len_high);
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uint32_t addr = (uint32_t)(entry.addr_low | entry.addr_high);
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printf("Region #%d: 0x%08X-0x%08X\n", i, addr, addr+len);
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}
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if (!mmap_init(&ctx)) {
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set_color(VGA_COLOR_RED);
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printf("Failed to create memory map\n");
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goto halt;
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}
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printf("Detected %d bytes of memory\n", ctx.available_bytes);
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printf("[KERNEL] Detected %d bytes of memory\n", ctx.available_bytes);
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// Create and load an IDT
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for (int i = 0; i < 32; i++) {
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@ -156,7 +144,7 @@ void kmain(struct multiboot_info *info) {
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goto halt;
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}
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printf("Using ACPI v1.0\n");
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printf("[KERNEL] Using ACPI v1.0\n");
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struct fadt *fadt = acpi_locate_sdt(ctx.rsdt, "FACP");
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if (!fadt) {
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@ -164,9 +152,9 @@ void kmain(struct multiboot_info *info) {
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printf("Failed to find FADT\n");
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goto halt;
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}
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printf("Found FADT at 0x%x\n", fadt);
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printf("[KERNEL] Found FADT at 0x%x\n", fadt);
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if (fadt->Flags & 1)
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printf("Legacy devices are supported\n");
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printf("[KERNEL] Legacy devices are supported\n");
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else {
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/*
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set_color(VGA_COLOR_RED);
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@ -176,10 +164,18 @@ void kmain(struct multiboot_info *info) {
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}
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pic_remap(PIC_1_START, PIC_2_START);
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// ACPI version 1.0 is so old that we assume that our PC supports the 8042 ps/2 controller
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initialize_8042ps2();
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encode_idt_entry(g_idt, 0x21, (uint32_t)&ps2_isr, GDT_SEGMENT_SELECTOR(GDT_KERNEL_CODE, 0x00), INT_GATE_32 | INT_RING0 | INT_PRESENT);
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asm volatile ("sti" ::);
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// Allocate 4KiB for stdout
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stdout.data = mmap_find_first_free_block(&ctx);
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stdout.next = NULL;
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// Allocate 4KiB for stdin
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stdin.data = mmap_find_first_free_block(&ctx);
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stdin.next = NULL;
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initialize_8042ps2();
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encode_idt_entry(g_idt, 0x21, (uint32_t)&ps2_isr, GDT_SEGMENT_SELECTOR(GDT_KERNEL_CODE, RING0), INT_GATE_32 | INT_RING0 | INT_PRESENT);
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asm volatile ("sti" ::);
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/*
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struct mcfg *mcfg = acpi_locate_sdt(ctx.rsdt, "MCFG");
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if (!mcfg) {
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set_color(VGA_COLOR_RED);
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@ -196,19 +192,62 @@ void kmain(struct multiboot_info *info) {
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ide_identify(ATA_PRIMARY, ATA_MASTER, ide_buf);
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}
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}
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*/
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set_color(VGA_COLOR_WHITE);
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void *buf = mmap_find_first_free_block(&ctx);
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ata_read_sector(ATA_PRIMARY, ATA_MASTER, 0, (uint8_t *)buf);
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// struct fat12_boot_sector *boot_sect = (struct fat12_boot_sector *)buf;
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// int fat_size = boot_sect->total_sectors_16 * boot_sect->bytes_per_sector;
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write_tss(5, 0x10, 0x0);
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write_tss(&tss, gdt, 5, 0x10, 0x0);
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tss_flush(0x2B);
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encode_idt_entry(g_idt, 0x80, (uint32_t)&syscall_isr, GDT_SEGMENT_SELECTOR(GDT_USER_CODE, RING3), INT_GATE_32 | INT_RING3 | INT_PRESENT);
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uint16_t cs_selector = 0x10; // Example code segment selector
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uint32_t eip = (uint32_t)&syscall; // Example entry point address
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uint32_t esp;
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// Get the current value of ESP
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__asm__ volatile ("mov %%esp, %0" : "=r"(esp));
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// Write to MSR_SYSENTER_CS (0x174)
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__asm__ volatile (
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"movl $0x174, %%ecx \n\t" // MSR address
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"movl %0, %%eax \n\t" // Lower 32 bits (cs_selector)
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"xor %%edx, %%edx \n\t" // Upper 32 bits (zero for 32-bit value)
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"wrmsr"
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:
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: "r"((uint32_t)cs_selector)
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: "eax", "ecx", "edx"
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);
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// Write to MSR_SYSENTER_ESP (0x175)
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__asm__ volatile (
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"movl $0x175, %%ecx \n\t" // MSR address
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"movl %0, %%eax \n\t" // Lower 32 bits (esp)
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"xor %%edx, %%edx \n\t" // Upper 32 bits (zero for 32-bit value)
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"wrmsr"
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:
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: "r"(esp)
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: "eax", "ecx", "edx"
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);
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// Write to MSR_SYSENTER_EIP (0x176)
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__asm__ volatile (
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"movl $0x176, %%ecx \n\t" // MSR address
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"movl %0, %%eax \n\t" // Lower 32 bits (eip)
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"xor %%edx, %%edx \n\t" // Upper 32 bits (zero for 32-bit value)
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"wrmsr"
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:
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: "r"(eip)
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: "eax", "ecx", "edx"
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);
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void *page = mmap_find_first_free_block(&ctx);
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ata_read_sector(ATA_PRIMARY, ATA_MASTER, 0, page);
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printf("[KERNEL] Init program loaded to 0x%08X\n", page);
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printf("[KERNEL] Transferring control... goodbye\n");
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set_color(VGA_COLOR_WHITE);
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// 4 KiB for stack
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void *stack_bottom = mmap_find_first_free_block(&ctx);
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void *stack_top = stack_bottom + 4096;
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switch_to_user_mode(stack_top, buf);
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void *stack_top = stack_bottom + 0x1000;
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MAGIC_BREAKPOINT
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switch_to_user_mode(stack_top, page);
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halt:
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for (;;) {}
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}
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10
mem.c
10
mem.c
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@ -19,14 +19,18 @@ void *mmap_block_to_physical(struct kernel_context *ctx, int block) {
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return 0;
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}
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void *memset(void *s, int c, uint32_t len) {
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void memset(void *s, int c, uint32_t len) {
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unsigned char *dst = s;
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while (len > 0) {
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*dst = (unsigned char) c;
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dst++;
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len--;
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}
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return s;
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}
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void memcpy(void *dest, void *src, int n) {
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for (int i=0; i<n; i++)
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((char *)dest)[i] = ((char *)src)[i];
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}
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@ -41,7 +45,6 @@ uint8_t mmap_init(struct kernel_context *ctx) {
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}
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ctx->mmap_size = ctx->available_bytes / BLOCK_SIZE / 8;
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printf("Memory map size: %d bytes\n", ctx->mmap_size);
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// Loop again to find the first region with enough space to hold the memory map
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int index = -1;
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@ -113,6 +116,7 @@ void *mmap_find_first_free_block(struct kernel_context *ctx) {
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uint32_t dword = ctx->mmap[index];
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if (!(dword & mask)) {
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mmap_set_block(ctx, i);
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return mmap_block_to_physical(ctx, i);
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}
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}
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@ -116,15 +116,45 @@ isr_stub_table:
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global ps2_isr
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ps2_isr:
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cli
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extern ps2_handler
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pushad
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cld
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and esp, 0xFFFFFFF0
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call ps2_handler
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popad
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iret
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global test
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test:
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push ebp
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mov ebp, esp
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mov eax, 1
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mov edi, 0
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mov esi, buf
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int 0x80
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jmp $
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buf: db "Hello from stdout!", 0
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global syscall_isr
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syscall_isr:
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xchg bx, bx
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pushad
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mov ecx, esp
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sysenter
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after_syscall:
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popad
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iret
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global syscall
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syscall:
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imul eax, eax, 4
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add eax, syscall_table
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pushad
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call [eax]
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popad
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mov edx, after_syscall
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sysexit
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; GDT for a flat memory layout
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; We get access to all memory and can utilize paging
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global gdt
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@ -167,6 +197,13 @@ gdtp:
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dw gdt_end - gdt - 1
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dd gdt
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||||
|
||||
global syscall_table
|
||||
syscall_table:
|
||||
extern syscall_read
|
||||
dd syscall_read
|
||||
|
||||
extern syscall_write
|
||||
dd syscall_write
|
||||
|
||||
; Reserve 16KiB of kernel stack space
|
||||
section .bss
|
||||
|
|
|
|||
3
ps2.c
3
ps2.c
|
|
@ -5,6 +5,7 @@
|
|||
#include <printf.h>
|
||||
#include <strcmp.h>
|
||||
#include <ide.h>
|
||||
#include <mem.h>
|
||||
|
||||
#define cpu_relax asm volatile ("pause" ::);
|
||||
|
||||
|
|
@ -54,6 +55,8 @@ void initialize_8042ps2() {
|
|||
outportb(PS2_8042_DATA, config);
|
||||
}
|
||||
|
||||
extern linked_mem_t stdin;
|
||||
|
||||
void ps2_handler() {
|
||||
uint8_t scancode = inportb(0x60);
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user