add syscall sched_yield

src/kxos-frame/src/config.rs

@@ -15,4 +15,4 @@ pub const PAGE_SIZE_BITS: usize = 0xc;
 
 pub const KVA_START: usize = (usize::MAX) << PAGE_SIZE_BITS;
 
-pub const DEFAULT_LOG_LEVEL: LogLevel = LogLevel::Info;
+pub const DEFAULT_LOG_LEVEL: LogLevel = LogLevel::Trace;

src/kxos-frame/src/lib.rs

@@ -35,6 +35,7 @@ use core::{mem, panic::PanicInfo};
 pub use self::error::Error;
 pub use self::prelude::Result;
 pub(crate) use self::sync::up::UPSafeCell;
+
 use alloc::vec::Vec;
 use bootloader::{
     boot_info::{FrameBuffer, MemoryRegionKind},
@@ -45,6 +46,8 @@ pub use trap::{allocate_irq, IrqAllocateHandle, TrapFrame};
 use trap::{IrqCallbackHandle, IrqLine};
 pub use vm::Pod;
 use x86_64_util::enable_common_cpu_features;
+pub use util::AlignExt;
+
 static mut IRQ_CALLBACK_LIST: Vec<IrqCallbackHandle> = Vec::new();
 
 #[cfg(not(feature = "serial_print"))]

src/kxos-frame/src/task/processor.rs

@@ -51,7 +51,9 @@ pub(crate) fn get_idle_task_cx_ptr() -> *mut TaskContext {
 
 /// call this function to switch to other task by using GLOBAL_SCHEDULER
 pub fn schedule() {
-    switch_to_task(fetch_task().expect("no more task found"));
+    if let Some(task) = fetch_task() {
+        switch_to_task(task);
+    }
 }
 
 /// call this function to switch to other task

src/kxos-frame/src/task/task.rs

@@ -128,7 +128,7 @@ impl Task {
     /// Note that this method cannot be simply named "yield" as the name is
     /// a Rust keyword.
     pub fn yield_now() {
-        todo!()
+        schedule();
     }
 
     /// Spawns a task that executes a function.

src/kxos-frame/src/util/align_ext.rs

@@ -2,6 +2,9 @@
 /// `u64`, and `usize`, to provide methods to make integers aligned to a
 /// power of two.
 pub trait AlignExt {
+    /// returns whether the number is a power of two
+    fn is_power_of_two(&self) -> bool;
+
     /// Returns to the smallest number that is greater than or equal to
     /// `self` and is a multiple of the given power of two.
     ///
@@ -41,6 +44,10 @@ macro_rules! impl_align_ext {
     ($( $uint_type:ty ),+,) => {
         $(
             impl AlignExt for $uint_type {
+                fn is_power_of_two(&self) -> bool {
+                    (*self != 0) && ((*self & (*self - 1)) == 0)
+                }
+
                 fn align_up(self, align: Self) -> Self {
                     assert!(align.is_power_of_two() && align >= 2);
                     self.checked_add(align - 1).unwrap() & !(align - 1)
@@ -69,29 +76,29 @@ mod test {
 
     #[test]
     fn test_align_up() {
-        let input_ns = [0, 1, 2, 9, 15, 21, 32, 47, 50];
-        let input_as = [2, 2, 2, 2, 4, 4, 8, 8, 8];
-        let output_ns = [0, 2, 2, 10, 16, 24, 32, 48, 56];
+        let input_ns = [0usize, 1, 2, 9, 15, 21, 32, 47, 50];
+        let input_as = [2usize, 2, 2, 2, 4, 4, 8, 8, 8];
+        let output_ns = [0usize, 2, 2, 10, 16, 24, 32, 48, 56];
 
         for i in 0..input_ns.len() {
             let n = input_ns[i];
             let a = input_as[i];
             let n2 = output_ns[i];
-            assert!(align_up(n, a) == n2);
+            assert!(n.align_up(a) == n2);
         }
     }
 
     #[test]
     fn test_align_down() {
-        let input_ns = [0, 1, 2, 9, 15, 21, 32, 47, 50];
-        let input_as = [2, 2, 2, 2, 4, 4, 8, 8, 8];
-        let output_ns = [0, 0, 2, 8, 12, 20, 32, 40, 48];
+        let input_ns = [0usize, 1, 2, 9, 15, 21, 32, 47, 50];
+        let input_as = [2usize, 2, 2, 2, 4, 4, 8, 8, 8];
+        let output_ns = [0usize, 0, 2, 8, 12, 20, 32, 40, 48];
 
         for i in 0..input_ns.len() {
             let n = input_ns[i];
             let a = input_as[i];
             let n2 = output_ns[i];
-            assert!(align_down(n, a) == n2);
+            assert!(n.align_down(a) == n2);
         }
     }
 }

src/kxos-std/src/lib.rs

@@ -44,6 +44,12 @@ pub fn init_process() {
         process.pid()
     );
 
+    let hello_c_content = read_hello_c_content();
+    // glibc requires the filename starts as "/"
+    let hello_c_filename = CString::new("/hello_c").unwrap();
+    let process = Process::spawn_user_process(hello_c_filename, hello_c_content);
+    info!("spawn hello_c process, pid = {}", process.pid());
+
     let fork_content = read_fork_content();
     let fork_filename = CString::new("fork").unwrap();
     let process = Process::spawn_user_process(fork_filename, fork_content);
@@ -52,13 +58,11 @@ pub fn init_process() {
         process.pid()
     );
 
-    let hello_c_content = read_hello_c_content();
-    // glibc requires the filename starts as "/"
-    let hello_c_filename = CString::new("/hello_c").unwrap();
-    let process = Process::spawn_user_process(hello_c_filename, hello_c_content);
-    info!("spawn hello_c process, pid = {}", process.pid());
-
-    loop {}
+    loop {
+        // We don't have preemptive scheduler now.
+        // The long running init process should yield its own execution to allow other tasks to go on.
+        Process::yield_now();
+    }
 }
 
 /// first process never return

src/kxos-std/src/memory/init_stack.rs

@@ -10,6 +10,7 @@ use kxos_frame::{
     config::PAGE_SIZE,
     debug,
     vm::{Vaddr, VmIo, VmPerm, VmSpace},
+    AlignExt,
 };
 
 use super::{
@@ -252,9 +253,8 @@ impl InitStack {
     }
     /// returns the u64 start address
     fn write_u64(&mut self, val: u64, vm_space: &VmSpace) -> u64 {
-        let start_address = align_down(self.pos - 8, 8);
+        let start_address = (self.pos - 8).align_down(8);
         self.pos = start_address;
-        // debug!("start_address: 0x{:x}", start_address);
         vm_space
             .write_val(start_address, &val)
             .expect("Write u64 failed");
@@ -289,16 +289,6 @@ impl InitStack {
     }
 }
 
-fn is_power_of_two(val: usize) -> bool {
-    (val != 0) && ((val & (val - 1)) == 0)
-}
-
-/// align should be the pow of 2
-fn align_down(vaddr: usize, align: usize) -> usize {
-    assert!(is_power_of_two(align));
-    vaddr & !(align - 1)
-}
-
 /// generate random [u8; 16].
 /// FIXME: generate really random value. Now only return array with fixed values.
 fn generate_random_for_aux_vec() -> [u8; 16] {

src/kxos-std/src/process/mod.rs

@@ -7,7 +7,6 @@ use alloc::{
     vec::Vec,
 };
 use kxos_frame::cpu::CpuContext;
-use kxos_frame::vm::{Vaddr, VmPerm};
 // use kxos_frame::{sync::SpinLock, task::Task, user::UserSpace};
 use kxos_frame::{
     debug,
@@ -20,7 +19,6 @@ use spin::Mutex;
 use crate::memory::mmap_area::MmapArea;
 use crate::memory::user_heap::UserHeap;
 use crate::process::task::create_forked_task;
-use crate::syscall::mmap::MMapFlags;
 
 use self::status::ProcessStatus;
 use self::task::create_user_task_from_elf;
@@ -140,6 +138,7 @@ impl Process {
         })
     }
 
+    /// returns the pid
     pub fn pid(&self) -> usize {
         self.pid
     }
@@ -183,10 +182,16 @@ impl Process {
         self.task.send_to_scheduler();
     }
 
+    /// yield the current process to allow other processes to run
+    pub fn yield_now() {
+        Task::yield_now();
+    }
+
     fn user_space(&self) -> Option<&Arc<UserSpace>> {
         self.user_space.as_ref()
     }
 
+    /// returns the vm space if the process does have, otherwise None
     pub fn vm_space(&self) -> Option<&VmSpace> {
         match self.user_space {
             None => None,
@@ -194,6 +199,7 @@ impl Process {
         }
     }
 
+    /// returns the user heap if the process does have, otherwise None
     pub fn user_heap(&self) -> Option<&UserHeap> {
         match self.user_vm {
             None => None,
@@ -201,6 +207,7 @@ impl Process {
         }
     }
 
+    /// returns the mmap area if the process does have, otherwise None
     pub fn mmap_area(&self) -> Option<&MmapArea> {
         match self.user_vm {
             None => None,
@@ -208,10 +215,13 @@ impl Process {
         }
     }
 
+    /// whether the process has child process
     pub fn has_child(&self) -> bool {
         self.children.lock().len() != 0
     }
 
+    /// get the first(and only) child process
+    /// FIXME: deal with multiple children processes
     pub fn get_child_process(&self) -> Arc<Process> {
         let children_lock = self.children.lock();
         let child_len = children_lock.len();
@@ -223,6 +233,7 @@ impl Process {
             .clone()
     }
 
+    /// Fork a child process
     /// WorkAround: This function only create a new process, but did not schedule the process to run
     pub fn fork(parent_context: CpuContext) -> Arc<Process> {
         let child_pid = new_pid();
@@ -271,29 +282,9 @@ impl Process {
         child
     }
 
-    pub fn mmap(&self, len: usize, vm_perm: VmPerm, flags: MMapFlags, offset: usize) -> Vaddr {
-        let mmap_area = self
-            .mmap_area()
-            .expect("mmap should work on process with mmap area");
-        let user_space = self
-            .user_space()
-            .expect("mmap should work on process with user space");
-        let vm_space = user_space.vm_space();
-        mmap_area.mmap(len, offset, vm_perm, flags, vm_space)
-    }
-
     pub fn filename(&self) -> Option<&CString> {
         self.filename.as_ref()
     }
-
-    //     pub fn copy_bytes_from_user(&self, vaddr: Vaddr, buf: &mut [u8]) {
-    //         self.user_space()
-    //             .unwrap()
-    //             .vm_space()
-    //             .read_bytes(vaddr, buf)
-    //             .unwrap();
-    //     }
-    // }
 }
 
 /// Get the init process

src/kxos-std/src/syscall/mod.rs

@@ -32,6 +32,7 @@ mod gettid;
 pub mod mmap;
 mod mprotect;
 mod readlink;
+mod sched_yield;
 mod tgkill;
 mod uname;
 mod write;
@@ -45,6 +46,7 @@ const SYS_BRK: u64 = 12;
 const SYS_RT_SIGACTION: u64 = 13;
 const SYS_RT_SIGPROCMASK: u64 = 14;
 const SYS_WRITEV: u64 = 20;
+const SYS_SCHED_YIELD: u64 = 24;
 const SYS_GETPID: u64 = 39;
 const SYS_FORK: u64 = 57;
 const SYS_EXIT: u64 = 60;

src/kxos-std/src/syscall/sched_yield.rs

@@ -0,0 +1,11 @@
+use kxos_frame::debug;
+
+use crate::{process::Process, syscall::SYS_SCHED_YIELD};
+
+use super::SyscallResult;
+
+pub fn sys_sched_yield() -> SyscallResult {
+    debug!("[syscall][id={}][SYS_SCHED_YIELD]", SYS_SCHED_YIELD);
+    Process::yield_now();
+    SyscallResult::Return(0)
+}