syscall-exec

os/Makefile

@@ -23,6 +23,8 @@ $(bin): kernel
 
 asm:
 	$(objdump) -d $(kernel) | less
+assembly:
+	$(objdump) -d $(kernel) > target/os.asm
 
 build: $(bin)
 
@@ -34,6 +36,8 @@ qemu: build
 		-machine virt \
 		-nographic \
 		-bios default \
-		-device loader,file=$(bin),addr=0x80200000
+		-device loader,file=$(bin),addr=0x80200000 \
+		-drive file=../usr/build/riscv64.img,if=none,format=raw,id=x0 \
+		-device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
 
 run: build qemu

os/src/context.rs

@@ -3,6 +3,7 @@ use riscv::register::sstatus;
 use riscv::register::{scause::Scause, sstatus::Sstatus};
 
 #[repr(C)]
+#[derive(Clone)]
 pub struct TrapFrame {
     pub x: [usize; 32],   // General registers
     pub sstatus: Sstatus, // Supervisor Status Register
@@ -11,7 +12,43 @@ pub struct TrapFrame {
     pub scause: Scause,   // Scause register: record the cause of exception/interrupt/trap
 }
 
+impl TrapFrame {
+    /// Constructs TrapFrame for a new kernel thread.
+    ///
+    /// The new thread starts at function `entry` with an usize argument `arg`.
+    /// The stack pointer will be set to `sp`.
+    fn new_kernel_thread(entry: extern "C" fn(usize) -> !, arg: usize, sp: usize) -> Self {
+        use core::mem::zeroed;
+        let mut tf: Self = unsafe { zeroed() };
+        tf.x[10] = arg; // a0
+        tf.x[2] = sp;
+        tf.sepc = entry as usize;
+        tf.sstatus = sstatus::read();
+        tf.sstatus.set_spie(true);
+        tf.sstatus.set_sie(false);
+        tf.sstatus.set_spp(sstatus::SPP::Supervisor);
+        tf
+    }
+
+    /// Constructs TrapFrame for a new user thread.
+    ///
+    /// The new thread starts at `entry_addr`.
+    /// The stack pointer will be set to `sp`.
+    pub fn new_user_thread(entry_addr: usize, sp: usize) -> Self {
+        use core::mem::zeroed;
+        let mut tf: Self = unsafe { zeroed() };
+        tf.x[2] = sp;
+        tf.sepc = entry_addr;
+        tf.sstatus = sstatus::read();
+        tf.sstatus.set_spie(true);
+        tf.sstatus.set_sie(false);
+        tf.sstatus.set_spp(sstatus::SPP::User);
+        tf
+    }
+}
+
 #[repr(C)]
+#[derive(Clone)]
 pub struct Context {
     pub content_addr: usize,
 }
@@ -31,6 +68,10 @@ impl Context {
         ContextContent::new_kernel_thread(entry, kstack_top, satp).push_at(kstack_top)
     }
 
+    pub unsafe fn new_fork(tf: &TrapFrame, kstack_top: usize, satp: usize) -> Context {
+        ContextContent::new_fork(tf, kstack_top, satp)
+    }
+
     pub unsafe fn append_initial_arguments(&self, args: [usize; 3]) {
         let contextContent = &mut *(self.content_addr as *mut ContextContent);
         contextContent.tf.x[10] = args[0];
@@ -98,6 +139,26 @@ impl ContextContent {
         }
     }
 
+    /// Fork a user process and get the new Context.
+    ///
+    /// The stack pointer in kernel mode will be set to `kstack_top`.
+    /// The SATP register will be set to `satp`.
+    /// All the other registers are same as the original.
+    unsafe fn new_fork(tf: &TrapFrame, kstack_top: usize, satp: usize) -> Context {
+        ContextContent {
+            ra: __trapret as usize,
+            satp,
+            s: [0; 12],
+            tf: {
+                let mut tf = tf.clone();
+                // fork function's ret value, the new process is 0
+                tf.x[10] = 0; // a0
+                tf
+            },
+        }
+        .push_at(kstack_top)
+    }
+
     unsafe fn push_at(self, stack_top: usize) -> Context {
         let ptr = (stack_top as *mut ContextContent).sub(1);
         *ptr = self;

os/src/drivers/mod.rs

@@ -0,0 +1 @@
+pub mod virtio_disk;