Add first user program hello_world.rs

user/src/bin/hello_world.rs

@@ -0,0 +1,11 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+#[no_mangle]
+fn main() -> i32 {
+    println!("Hello, world!");
+    0
+}

user/src/console.rs

@@ -0,0 +1,29 @@
+use core::fmt::{self, Write};
+use crate::syscall::{STDOUT, sys_write};
+
+struct Stdout;
+
+impl Write for Stdout {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        sys_write(STDOUT, s.as_bytes());
+        Ok(())
+    }
+}
+
+pub fn print(args: fmt::Arguments) {
+    Stdout.write_fmt(args).unwrap();
+}
+
+#[macro_export]
+macro_rules! print {
+    ($fmt: literal $(, $($arg: tt)+)?) => {
+        $crate::console::print(format_args!($fmt $(, $($arg)+)?));
+    }
+}
+
+#[macro_export]
+macro_rules! println {
+    ($fmt: literal $(, $($arg: tt)+)?) => {
+        $crate::console::print(format_args!(concat!($fmt, "\n") $(, $($arg)+)?));
+    }
+}

user/src/lang_items.rs

@@ -0,0 +1,10 @@
+#[panic_handler]
+fn panic_handler(panic_info: &core::panic::PanicInfo) -> ! {
+    let err = panic_info.message().unwrap();
+    if let Some(location) = panic_info.location() {
+        println!("Panicked at {}:{}, {}", location.file(), location.line(), err);
+    } else {
+        println!("Panicked: {}", err);
+    }
+    loop {}
+}

user/src/lib.rs

@@ -0,0 +1,23 @@
+#![no_std]
+#![feature(llvm_asm)]
+#![feature(linkage)]
+#![feature(panic_info_message)]
+
+#[macro_use]
+pub mod console;
+mod syscall;
+mod lang_items;
+
+#[no_mangle]
+#[link_section = ".text.entry"]
+pub extern "C" fn _start() -> ! {
+    main();
+    loop {}
+}
+
+#[linkage = "weak"]
+#[no_mangle]
+fn main() -> i32 {
+    panic!("Cannot find main!");
+}
+

user/src/linker.ld

@@ -0,0 +1,26 @@
+OUTPUT_ARCH(riscv)
+ENTRY(_start)
+
+BASE_ADDRESS = 0x80040000;
+
+SECTIONS
+{
+    . = BASE_ADDRESS;
+    .text : {
+        *(.text.entry)
+        *(.text .text.*)
+    }
+    .rodata : {
+        *(.rodata .rodata.*)
+    }
+    .data : {
+        *(.data .data.*)
+    }
+    .bss : {
+        *(.bss .bss.*)
+    }
+    /DISCARD/ : {
+        *(.eh_frame)
+        *(.debug*)
+    }
+}

user/src/syscall.rs

@@ -0,0 +1,20 @@
+pub const STDOUT: usize = 1;
+
+const SYSCALL_WRITE: usize = 64;
+
+fn syscall(id: usize, args: [usize; 3]) -> isize {
+    let mut ret: isize;
+    unsafe {
+        llvm_asm!("ecall"
+            : "={x10}" (ret)
+            : "{x10}" (args[0]), "{x11}" (args[1]), "{x12}" (args[2]), "{x17}" (id)
+            : "memory"
+            : "volatile"
+        );
+    }
+    ret
+}
+
+pub fn sys_write(fd: usize, buffer: &[u8]) -> isize {
+    syscall(SYSCALL_WRITE, [fd, buffer.as_ptr() as usize, buffer.len()])
+}