lab4

lab4/.gitignore

@@ -0,0 +1,6 @@
+.vscode
+build
+rootfs
+temp
+*.img
+*.dtb

lab4/Makefile

@@ -0,0 +1,36 @@
+ARMGNU ?= aarch64-linux-gnu
+
+CFLAGS = -Iinclude -nostdlib -nostartfiles -ffreestanding -mgeneral-regs-only -Wall -g
+ASMFLAGS = -Iinclude
+QEMUFLAGS = -M raspi3b -display none -serial null -serial stdio
+
+SRC_DIR = src
+BUILD_DIR = build
+
+all: clean kernel8.img
+
+clean:
+	rm -rf $(BUILD_DIR) *.img
+
+$(BUILD_DIR)/%.o: $(SRC_DIR)/%.c
+	mkdir -p $(@D)
+	$(ARMGNU)-gcc $(CFLAGS)   -c $< -o $@
+
+$(BUILD_DIR)/_%.o: %.S
+	$(ARMGNU)-gcc $(ASMFLAGS) -c $< -o $@
+
+SRC_FILES  = $(wildcard $(SRC_DIR)/*.c)
+ASM_FILES  = $(wildcard *.S)
+OBJ_FILES  = $(SRC_FILES:$(SRC_DIR)/%.c=$(BUILD_DIR)/%.o)
+OBJ_FILES += $(ASM_FILES:%.S=$(BUILD_DIR)/_%.o)
+
+kernel8.img: linker.ld $(OBJ_FILES)
+	$(ARMGNU)-ld -T linker.ld -o $(BUILD_DIR)/kernel8.elf $(OBJ_FILES)
+	$(ARMGNU)-objcopy -O binary  $(BUILD_DIR)/kernel8.elf kernel8.img
+
+qemu: all kernel8.img initramfs.cpio bcm2710-rpi-3-b-plus.dtb
+	clear
+	qemu-system-aarch64 $(QEMUFLAGS) -kernel kernel8.img -initrd initramfs.cpio -dtb bcm2710-rpi-3-b-plus.dtb
+
+debug: all kernel8.img initramfs.cpio bcm2710-rpi-3-b-plus.dtb
+	qemu-system-aarch64 $(QEMUFLAGS) -kernel kernel8.img -initrd initramfs.cpio -dtb bcm2710-rpi-3-b-plus.dtb -S -s -d int

lab4/bootloader/Makefile

@@ -0,0 +1,19 @@
+ARMGNU ?= aarch64-linux-gnu
+CFLAGS = -nostdlib -nostartfiles -ffreestanding -mgeneral-regs-only -Wall -g
+QEMUFLAGS = -M raspi3b -display none -serial null -serial pty
+
+all: clean bootloader.img
+
+clean:
+	rm -rf build *.img
+
+bootloader.img:
+	mkdir -p build
+	$(ARMGNU)-gcc $(CFLAGS) -c main.c  -o build/main.o
+	$(ARMGNU)-gcc $(CFLAGS) -c start.S -o build/start.o
+	$(ARMGNU)-gcc $(CFLAGS) -c boot.c  -o build/boot.o
+	$(ARMGNU)-ld -T linker.ld -o build/bootloader.elf build/main.o build/start.o build/boot.o
+	$(ARMGNU)-objcopy -O binary build/bootloader.elf bootloader.img
+
+qemu: clean bootloader.img
+	qemu-system-aarch64 $(QEMUFLAGS) -kernel bootloader.img -initrd ../initramfs.cpio -dtb ../bcm2710-rpi-3-b-plus.dtb

lab4/bootloader/boot.c

@@ -0,0 +1,61 @@
+#include "boot.h"
+
+void init_uart() {
+  // Configure GPIO pins
+  register unsigned int r = *GPFSEL1;
+  r &= ~((7 << 12) | (7 << 15));
+  r |= (2 << 12) | (2 << 15);
+  *GPFSEL1 = r;
+
+  *GPPUD = 0;
+  for (int i = 0; i < 150; i++) asm volatile("nop");
+  *GPPUDCLK0 = (1 << 14) | (1 << 15);
+  for (int i = 0; i < 150; i++) asm volatile("nop");
+  *GPPUD = 0;
+  *GPPUDCLK0 = 0;
+
+  *AUX_ENABLE |= 1;
+  *AUX_MU_CNTL = 0;
+  *AUX_MU_IER = 0;
+  *AUX_MU_LCR = 3;
+  *AUX_MU_MCR = 0;
+  *AUX_MU_BAUD = 270;
+  *AUX_MU_IIR = 6;
+  *AUX_MU_CNTL = 3;
+}
+
+char uart_recv() {
+  while (!(*AUX_MU_LSR & 0x01)) asm volatile("nop");
+  return (char)(*AUX_MU_IO);
+}
+
+void uart_putc(char c) {
+  if (c == '\n') uart_putc('\r');
+  while (!(*AUX_MU_LSR & 0x20)) asm volatile("nop");
+  *AUX_MU_IO = c;
+}
+
+void uart_puts(const char *s) {
+  while (*s) uart_putc(*s++);
+}
+
+int atoi(const char *s) {
+  int result = 0;
+  int sign = 1;
+  int i = 0;
+
+  while (s[i] == ' ') i++;
+
+  if (s[i] == '-') {
+    sign = -1;
+    i++;
+  } else if (s[i] == '+')
+    i++;
+
+  while (s[i] >= '0' && s[i] <= '9') {
+    result = result * 10 + (s[i] - '0');
+    i++;
+  }
+
+  return sign * result;
+}

lab4/bootloader/boot.h

@@ -0,0 +1,49 @@
+#ifndef BOOT_H
+#define BOOT_H
+
+/* ==================== GPIO ==================== */
+#define MMIO_BASE 0x3F000000
+
+#define GPFSEL0 ((volatile unsigned int *)(MMIO_BASE + 0x00200000))
+#define GPFSEL1 ((volatile unsigned int *)(MMIO_BASE + 0x00200004))
+#define GPFSEL2 ((volatile unsigned int *)(MMIO_BASE + 0x00200008))
+#define GPFSEL3 ((volatile unsigned int *)(MMIO_BASE + 0x0020000C))
+#define GPFSEL4 ((volatile unsigned int *)(MMIO_BASE + 0x00200010))
+#define GPFSEL5 ((volatile unsigned int *)(MMIO_BASE + 0x00200014))
+#define GPSET0 ((volatile unsigned int *)(MMIO_BASE + 0x0020001C))
+#define GPSET1 ((volatile unsigned int *)(MMIO_BASE + 0x00200020))
+#define GPCLR0 ((volatile unsigned int *)(MMIO_BASE + 0x00200028))
+#define GPCLR1 ((volatile unsigned int *)(MMIO_BASE + 0x0020002C))
+#define GPLEV0 ((volatile unsigned int *)(MMIO_BASE + 0x00200034))
+#define GPLEV1 ((volatile unsigned int *)(MMIO_BASE + 0x00200038))
+#define GPEDS0 ((volatile unsigned int *)(MMIO_BASE + 0x00200040))
+#define GPEDS1 ((volatile unsigned int *)(MMIO_BASE + 0x00200044))
+#define GPHEN0 ((volatile unsigned int *)(MMIO_BASE + 0x00200064))
+#define GPHEN1 ((volatile unsigned int *)(MMIO_BASE + 0x00200068))
+#define GPPUD ((volatile unsigned int *)(MMIO_BASE + 0x00200094))
+#define GPPUDCLK0 ((volatile unsigned int *)(MMIO_BASE + 0x00200098))
+#define GPPUDCLK1 ((volatile unsigned int *)(MMIO_BASE + 0x0020009C))
+
+/* ==================== UART ==================== */
+#define AUX_ENABLE ((volatile unsigned int *)(MMIO_BASE + 0x00215004))
+#define AUX_MU_IO ((volatile unsigned int *)(MMIO_BASE + 0x00215040))
+#define AUX_MU_IER ((volatile unsigned int *)(MMIO_BASE + 0x00215044))
+#define AUX_MU_IIR ((volatile unsigned int *)(MMIO_BASE + 0x00215048))
+#define AUX_MU_LCR ((volatile unsigned int *)(MMIO_BASE + 0x0021504C))
+#define AUX_MU_MCR ((volatile unsigned int *)(MMIO_BASE + 0x00215050))
+#define AUX_MU_LSR ((volatile unsigned int *)(MMIO_BASE + 0x00215054))
+#define AUX_MU_MSR ((volatile unsigned int *)(MMIO_BASE + 0x00215058))
+#define AUX_MU_SCRATCH ((volatile unsigned int *)(MMIO_BASE + 0x0021505C))
+#define AUX_MU_CNTL ((volatile unsigned int *)(MMIO_BASE + 0x00215060))
+#define AUX_MU_STAT ((volatile unsigned int *)(MMIO_BASE + 0x00215064))
+#define AUX_MU_BAUD ((volatile unsigned int *)(MMIO_BASE + 0x00215068))
+
+void init_uart();
+char uart_recv();
+void uart_putc(char c);
+void uart_puts(const char *s);
+
+/* ==================== UTILS ==================== */
+int atoi(const char *s);
+
+#endif  // BOOT_H

lab4/bootloader/linker.ld

@@ -0,0 +1,16 @@
+SECTIONS
+{
+	. = 0x60000;
+	__loader_start = .;
+	.text : { *(.text.boot) *(.text) }
+	.rodata : { *(.rodata) }
+	.data : { *(.data) }
+	.bss : {
+		__bss_start = .;
+		*(.bss)
+		__bss_end = .;
+	}
+	__loader_end = .;
+}
+__bss_size = (__bss_end - __bss_start) >> 3;
+__loader_size = (__loader_end - __loader_start) >> 3;

lab4/bootloader/main.c

@@ -0,0 +1,42 @@
+#include "boot.h"
+
+int main() {
+  init_uart();
+  uart_puts("\033[2J\033[H");
+  uart_puts(
+      "UART Bootloader\n"
+      "Waiting for kernel...\n");
+
+  // Get kernel image size
+  char buf[16] = {0};
+  for (int i = 0; i < 16; i++) {
+    buf[i] = uart_recv();
+    if (buf[i] == '\n') {
+      buf[i] = '\0';
+      break;
+    }
+  }
+
+  // Load kernel image
+  uart_puts("Kernel size: ");
+  uart_puts(buf);
+  uart_puts(" bytes.\n");
+  uart_puts("Loading the kernel image...\n");
+
+  unsigned int size = atoi(buf);
+  char *kernel = (char *)0x80000;
+  while (size--) *kernel++ = uart_recv();
+
+  // Restore registers x0 x1 x2 x3
+  // Jump to the new kernel
+  asm volatile(
+      ""
+      "mov x0, x10;"
+      "mov x1, x11;"
+      "mov x2, x12;"
+      "mov x3, x13;"
+      "mov x30, 0x80000;"
+      "ret;");
+
+  return 0;
+}

lab4/bootloader/start.S

@@ -0,0 +1,40 @@
+.section ".text.boot"
+
+.global _start
+
+_start:
+    /* save registers x0 x1 x2 x3 */
+    mov x10, x0 /* dtb_base address */
+    mov x11, x1
+    mov x12, x2
+    mov x12, x3
+
+    /* relocate bootloader */
+    ldr x1, =0x80000
+    ldr x2, =__loader_start // 0x60000
+    ldr w3, =__loader_size
+
+relocate:
+    ldr x4, [x1], #8
+    str x4, [x2], #8
+    sub w3, w3, #1
+    cbnz w3, relocate
+
+    /* set stack pointer */
+    ldr x1, =_start
+    mov sp, x1
+
+    /* clear bss section */
+    ldr x1, =__bss_start
+    ldr w2, =__bss_size
+
+bss_reset:
+    cbz w2, run_main
+    str xzr, [x1], #8
+    sub w2, w2, #1
+    cbnz w2, bss_reset
+
+run_main:
+    /* branch to main function */
+    bl main-0x20000
+    b run_main

lab4/include/command.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#define MAX_BUF_SIZE 1024
+#define END_OF_COMMAND_LIST "NULL"
+
+struct command {
+  const char *name;
+  const char *help;
+  void (*func)(void);
+};
+
+extern struct command commands[];
+extern unsigned int BOARD_REVISION;
+extern unsigned int BASE_MEMORY;
+extern unsigned int NUM_PAGES;
+
+// Commands
+void cmd_help();
+void cmd_hello();
+void cmd_reboot();
+void cmd_cancel();
+void cmd_info();
+void cmd_cat();
+void cmd_run();
+void cmd_clear();
+void cmd_timer();
+void cmd_mem();
+void cmd_bd();
+void cmd_fm();
+void cmd_ca();
+void cmd_lab();

lab4/include/devtree.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <stdint.h>
+
+struct fdt_header {
+  uint32_t magic;
+  uint32_t totalsize;
+  uint32_t off_dt_struct;
+  uint32_t off_dt_strings;
+  uint32_t off_mem_rsvmap;
+  uint32_t version;
+  uint32_t last_comp_version;
+  uint32_t boot_cpuid_phys;
+  uint32_t size_dt_strings;
+  uint32_t size_dt_struct;
+};
+
+uint32_t be2le(const void *s);
+void fdt_traverse(void (*callback)(void *, char *));