Add syscall alarm

framework/aster-frame/src/timer.rs

@@ -58,7 +58,7 @@ impl Timer {
     ///
     /// If a timeout value is already set, the timeout value will be refreshed.
     ///
-    pub fn set(self: Arc<Self>, timeout: Duration) {
+    pub fn set(self: &Arc<Self>, timeout: Duration) {
         let mut lock = self.inner.lock_irq_disabled();
         match &lock.timer_callback {
             Some(callback) => {

kernel/aster-nix/src/process/posix_thread/builder.rs

@@ -2,15 +2,18 @@
 
 use aster_frame::user::UserSpace;
 
-use super::PosixThread;
+use super::{PosixThread, PosixThreadExt, RealTimer};
 use crate::{
     prelude::*,
     process::{
         posix_thread::name::ThreadName,
-        signal::{sig_mask::SigMask, sig_queues::SigQueues},
+        signal::{
+            constants::SIGALRM, sig_mask::SigMask, sig_queues::SigQueues,
+            signals::kernel::KernelSignal,
+        },
         Credentials, Process,
     },
-    thread::{status::ThreadStatus, task::create_new_user_task, thread_table, Thread, Tid},
+    thread::{status::ThreadStatus, task, thread_table, Thread, Tid},
 };
 
 /// The builder to build a posix thread
@@ -90,8 +93,23 @@ impl PosixThreadBuilder {
             sig_queues,
             is_main_thread,
         } = self;
+
+        let real_timer = RealTimer::new(move || {
+            let process = {
+                let Some(current_thread) = thread_table::get_thread(tid) else {
+                    return;
+                };
+                let posix_thread = current_thread.as_posix_thread().unwrap();
+                posix_thread.process()
+            };
+
+            let signal = KernelSignal::new(SIGALRM);
+            process.enqueue_signal(signal);
+        })
+        .unwrap();
+
         let thread = Arc::new_cyclic(|thread_ref| {
-            let task = create_new_user_task(user_space, thread_ref.clone());
+            let task = task::create_new_user_task(user_space, thread_ref.clone());
             let status = ThreadStatus::Init;
             let posix_thread = PosixThread {
                 process,
@@ -100,6 +118,7 @@ impl PosixThreadBuilder {
                 set_child_tid: Mutex::new(set_child_tid),
                 clear_child_tid: Mutex::new(clear_child_tid),
                 credentials,
+                real_timer: Mutex::new(real_timer),
                 sig_mask: Mutex::new(sig_mask),
                 sig_queues: Mutex::new(sig_queues),
                 sig_context: Mutex::new(None),

kernel/aster-nix/src/process/posix_thread/mod.rs

@@ -26,11 +26,13 @@ pub mod futex;
 mod name;
 mod posix_thread_ext;
 mod robust_list;
+mod timer;
 
 pub use builder::PosixThreadBuilder;
 pub use name::{ThreadName, MAX_THREAD_NAME_LEN};
 pub use posix_thread_ext::PosixThreadExt;
 pub use robust_list::RobustListHead;
+pub use timer::RealTimer;
 
 pub struct PosixThread {
     // Immutable part
@@ -50,10 +52,13 @@ pub struct PosixThread {
     /// Process credentials. At the kernel level, credentials are a per-thread attribute.
     credentials: Credentials,
 
-    // signal
-    /// blocked signals
+    /// The timer counts down in real (i.e., wall clock) time
+    real_timer: Mutex<RealTimer>,
+
+    // Signal
+    /// Blocked signals
     sig_mask: Mutex<SigMask>,
-    /// thread-directed sigqueue
+    /// Thread-directed sigqueue
     sig_queues: Mutex<SigQueues>,
     /// Signal handler ucontext address
     /// FIXME: This field may be removed. For glibc applications with RESTORER flag set, the sig_context is always equals with rsp.
@@ -114,13 +119,13 @@ impl PosixThread {
             let receiver_sid = self.process().session().unwrap().sid();
             if receiver_sid == sender.sid() {
                 return Ok(());
-            } else {
+            }
+
             return_errno_with_message!(
                 Errno::EPERM,
                 "sigcont requires that sender and receiver belongs to the same session"
             );
         }
-        }
 
         let (receiver_ruid, receiver_suid) = {
             let credentials = self.credentials();
@@ -141,6 +146,10 @@ impl PosixThread {
         return_errno_with_message!(Errno::EPERM, "sending signal to the thread is not allowed.");
     }
 
+    pub fn real_timer(&self) -> &Mutex<RealTimer> {
+        &self.real_timer
+    }
+
     pub(in crate::process) fn enqueue_signal(&self, signal: Box<dyn Signal>) {
         self.sig_queues.lock().enqueue(signal);
     }
@@ -233,6 +242,8 @@ impl PosixThread {
             thread_table::remove_thread(tid);
         }
 
+        self.real_timer.lock().clear();
+
         if self.is_main_thread() || self.is_last_thread() {
             // exit current process.
             debug!("self is main thread or last thread");

kernel/aster-nix/src/process/posix_thread/timer.rs

@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use core::time::Duration;
+
+use crate::{
+    prelude::*,
+    thread::work_queue::{submit_work_item, work_item::WorkItem, WorkPriority},
+    time::SystemTime,
+};
+
+/// A timer that counts down in real (wall clock) time to run delayed callbacks in process context.
+///
+/// Unlike the `Timer` in `aster-frame`, the callbacks of this `RealTimer` will be executed in process
+/// context instead of interrupt context. This leads to two differences:
+///
+/// 1. The callbacks of this `RealTimer` can sleep, whereas the callbacks of `Timer` in `aster-frame` cannot.
+/// 2. The callbacks of this `RealTimer` may be delayed by an arbitrary amount of time due to scheduler strategy.
+///
+/// Note that the callbacks may not be executed in the process context of the timer's creator, so macros such
+/// as `current` and `current_thread` should **NOT** be used in the callback.
+///
+/// # Example
+/// ```rust
+/// let current_tid = current_thread!().tid();
+/// let timer = RealTimer::new(move || {
+///     let current_thread = thread_table::get_thread(current_tid);
+///     let posix_thread = current_thread.as_posix_thread().unwrap();
+///     let process = posix_thread.process();
+///     println!("Task executed for PID: {}", process.pid());
+/// }, Duration::from_secs(1));
+pub struct RealTimer {
+    timer: Arc<aster_frame::timer::Timer>,
+    expired_time: Option<SystemTime>,
+}
+
+impl RealTimer {
+    /// Creates a new `RealTimer`. The `callback` parameter will be called once the timeout is reached.
+    pub fn new(callback: impl Fn() + Send + Sync + Copy + 'static) -> Result<Self> {
+        let timer = {
+            aster_frame::timer::Timer::new(move |timer| {
+                let work_func = Box::new(callback);
+                let work_item = { Arc::new(WorkItem::new(work_func)) };
+                // FIXME: set a higher priority like `WorkPriority::Alarm`.
+                submit_work_item(work_item, WorkPriority::High);
+            })?
+        };
+
+        Ok(Self {
+            timer,
+            expired_time: None,
+        })
+    }
+
+    /// Sets a new timeout value. If the old timeout is already set, the timeout will be refreshed.
+    pub fn set(&mut self, timeout: Duration) -> Result<()> {
+        assert_ne!(timeout, ZERO_DURATION);
+
+        let new_expired_time = {
+            let now = SystemTime::now();
+            now.checked_add(timeout)
+                .ok_or_else(|| Error::with_message(Errno::EINVAL, "Invalid duration"))?
+        };
+
+        self.expired_time = Some(new_expired_time);
+
+        self.timer.set(timeout);
+
+        Ok(())
+    }
+
+    /// Returns the remaining time until the task is executed. If the `timer` is expired or cleared,
+    /// this method will return zero.
+    pub fn remain(&self) -> Duration {
+        let Some(expired_time) = &self.expired_time else {
+            return ZERO_DURATION;
+        };
+
+        let now = SystemTime::now();
+        match expired_time.duration_since(&now) {
+            Ok(duration) => duration,
+            Err(_) => ZERO_DURATION,
+        }
+    }
+
+    /// Returns whether the timer has expired.
+    pub fn is_expired(&self) -> bool {
+        self.remain() == ZERO_DURATION
+    }
+
+    /// Clears the timer.
+    pub fn clear(&mut self) {
+        self.timer.clear();
+        self.expired_time = None;
+    }
+}
+
+impl Drop for RealTimer {
+    fn drop(&mut self) {
+        self.timer.clear();
+    }
+}
+
+impl PartialEq for RealTimer {
+    fn eq(&self, other: &Self) -> bool {
+        self.expired_time == other.expired_time
+    }
+}
+
+impl Eq for RealTimer {}
+
+const ZERO_DURATION: Duration = Duration::new(0, 0);

kernel/aster-nix/src/syscall/alarm.rs

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use core::time::Duration;
+
+use super::{SyscallReturn, SYS_ALARM};
+use crate::{log_syscall_entry, prelude::*, process::posix_thread::PosixThreadExt};
+
+pub fn sys_alarm(seconds: u32) -> Result<SyscallReturn> {
+    log_syscall_entry!(SYS_ALARM);
+    debug!("seconds = {}", seconds);
+
+    let current_thread = current_thread!();
+    let mut real_timer = {
+        let posix_thread = current_thread.as_posix_thread().unwrap();
+        posix_thread.real_timer().lock()
+    };
+
+    let remaining_secs = real_timer.remain().as_secs();
+
+    if seconds == 0 {
+        // Clear previous timer
+        real_timer.clear();
+        return Ok(SyscallReturn::Return(remaining_secs as _));
+    }
+
+    real_timer.set(Duration::from_secs(seconds as u64))?;
+
+    Ok(SyscallReturn::Return(remaining_secs as _))
+}

kernel/aster-nix/src/syscall/mod.rs

@@ -5,15 +5,16 @@
 use aster_frame::cpu::UserContext;
 
 use self::{
-    accept::sys_accept, bind::sys_bind, connect::sys_connect, execve::sys_execveat,
-    getgroups::sys_getgroups, getpeername::sys_getpeername, getrandom::sys_getrandom,
-    getresgid::sys_getresgid, getresuid::sys_getresuid, getsid::sys_getsid,
-    getsockname::sys_getsockname, getsockopt::sys_getsockopt, listen::sys_listen,
-    pread64::sys_pread64, recvfrom::sys_recvfrom, sendto::sys_sendto, setfsgid::sys_setfsgid,
-    setfsuid::sys_setfsuid, setgid::sys_setgid, setgroups::sys_setgroups, setregid::sys_setregid,
-    setresgid::sys_setresgid, setresuid::sys_setresuid, setreuid::sys_setreuid, setsid::sys_setsid,
-    setsockopt::sys_setsockopt, setuid::sys_setuid, shutdown::sys_shutdown,
-    sigaltstack::sys_sigaltstack, socket::sys_socket, socketpair::sys_socketpair,
+    accept::sys_accept, alarm::sys_alarm, bind::sys_bind, connect::sys_connect,
+    execve::sys_execveat, getgroups::sys_getgroups, getpeername::sys_getpeername,
+    getrandom::sys_getrandom, getresgid::sys_getresgid, getresuid::sys_getresuid,
+    getsid::sys_getsid, getsockname::sys_getsockname, getsockopt::sys_getsockopt,
+    listen::sys_listen, pread64::sys_pread64, recvfrom::sys_recvfrom, sendto::sys_sendto,
+    setfsgid::sys_setfsgid, setfsuid::sys_setfsuid, setgid::sys_setgid, setgroups::sys_setgroups,
+    setregid::sys_setregid, setresgid::sys_setresgid, setresuid::sys_setresuid,
+    setreuid::sys_setreuid, setsid::sys_setsid, setsockopt::sys_setsockopt, setuid::sys_setuid,
+    shutdown::sys_shutdown, sigaltstack::sys_sigaltstack, socket::sys_socket,
+    socketpair::sys_socketpair,
 };
 use crate::{
     prelude::*,
@@ -96,6 +97,7 @@ use crate::{
 
 mod accept;
 mod access;
+mod alarm;
 mod arch_prctl;
 mod bind;
 mod brk;
@@ -257,6 +259,7 @@ define_syscall_nums!(
     SYS_DUP = 32,
     SYS_DUP2 = 33,
     SYS_PAUSE = 34,
+    SYS_ALARM = 37,
     SYS_GETPID = 39,
     SYS_SOCKET = 41,
     SYS_CONNECT = 42,
@@ -443,6 +446,7 @@ pub fn syscall_dispatch(
         SYS_DUP => syscall_handler!(1, sys_dup, args),
         SYS_DUP2 => syscall_handler!(2, sys_dup2, args),
         SYS_PAUSE => syscall_handler!(0, sys_pause),
+        SYS_ALARM => syscall_handler!(1, sys_alarm, args),
         SYS_GETPID => syscall_handler!(0, sys_getpid),
         SYS_SOCKET => syscall_handler!(3, sys_socket, args),
         SYS_CONNECT => syscall_handler!(3, sys_connect, args),

regression/syscall_test/Makefile

@@ -3,7 +3,7 @@
 TESTS ?= chmod_test chown_test fsync_test getdents_test link_test lseek_test mkdir_test \
 		open_create_test open_test pty_test read_test rename_test stat_test \
 		statfs_test symlink_test sync_test truncate_test uidgid_test unlink_test \
-		vdso_clock_gettime_test write_test
+		vdso_clock_gettime_test write_test alarm_test
 
 MKFILE_PATH := $(abspath $(lastword $(MAKEFILE_LIST)))
 CUR_DIR := $(patsubst %/,%,$(dir $(MKFILE_PATH)))

regression/syscall_test/blocklists/alarm_test

@@ -0,0 +1,2 @@
+AlarmTest.UserModeSpinning
+AlarmTest.Restart_NoRandomSave