Merge pull request #23 from Loremkang/master

Basically implement System V Semaphores

kernel/src/arch/x86_64/acpi.rs

@@ -12,8 +12,7 @@ impl AcpiHandler for Handler {
     ) -> PhysicalMapping<T> {
         PhysicalMapping {
             physical_start: physical_address,
-            virtual_start: NonNull::new(phys_to_virt(physical_address) as *mut T)
-                .unwrap(),
+            virtual_start: NonNull::new(phys_to_virt(physical_address) as *mut T).unwrap(),
             region_length: size,
             mapped_length: size,
         }

kernel/src/ipc/mod.rs

@@ -0,0 +1,72 @@
+mod semary;
+
+pub use self::semary::*;
+use alloc::collections::BTreeMap;
+use alloc::sync::Arc;
+
+/// Semaphore table in a process
+#[derive(Default)]
+pub struct SemProc {
+    /// Semaphore arrays
+    arrays: BTreeMap<SemId, Arc<SemArray>>,
+    /// Undo operations when process terminates
+    undos: BTreeMap<(SemId, SemNum), SemOp>,
+}
+
+/// Semaphore set identifier (in a process)
+type SemId = usize;
+
+/// Semaphore number (in an array)
+type SemNum = u16;
+
+/// Semaphore operation value
+type SemOp = i16;
+
+impl SemProc {
+    /// Insert the `array` and return its ID
+    pub fn add(&mut self, array: Arc<SemArray>) -> SemId {
+        let id = self.get_free_id();
+        self.arrays.insert(id, array);
+        id
+    }
+    /// Get a free ID
+    fn get_free_id(&self) -> SemId {
+        (0..).find(|i| self.arrays.get(i).is_none()).unwrap()
+    }
+    /// Get an semaphore set by `id`
+    pub fn get(&self, id: SemId) -> Option<Arc<SemArray>> {
+        self.arrays.get(&id).map(|a| a.clone())
+    }
+    /// Add an undo operation
+    pub fn add_undo(&mut self, id: SemId, num: SemNum, op: SemOp) {
+        let old_val = *self.undos.get(&(id, num)).unwrap_or(&0);
+        let new_val = old_val - op;
+        self.undos.insert((id, num), new_val);
+    }
+}
+
+/// Fork the semaphore table. Clear undo info.
+impl Clone for SemProc {
+    fn clone(&self) -> Self {
+        SemProc {
+            arrays: self.arrays.clone(),
+            undos: BTreeMap::default(),
+        }
+    }
+}
+
+/// Auto perform semaphores undo on drop
+impl Drop for SemProc {
+    fn drop(&mut self) {
+        for (&(id, num), &op) in self.undos.iter() {
+            debug!("semundo: id: {}, num: {}, op: {}", id, num, op);
+            let sem_array = self.arrays[&id].clone();
+            let sem = &sem_array[num as usize];
+            match op {
+                1 => sem.release(),
+                0 => {}
+                _ => unimplemented!("Semaphore: semundo.(Not 1)"),
+            }
+        }
+    }
+}

kernel/src/ipc/semary.rs

@@ -0,0 +1,49 @@
+use crate::sync::Semaphore;
+use crate::sync::SpinLock as Mutex;
+use alloc::{boxed::Box, collections::BTreeMap, string::String, sync::Arc, sync::Weak, vec::Vec};
+use core::ops::Index;
+use spin::RwLock;
+
+/// A System V semaphore set
+pub struct SemArray {
+    key: usize,
+    sems: Vec<Semaphore>,
+}
+
+impl Index<usize> for SemArray {
+    type Output = Semaphore;
+    fn index(&self, idx: usize) -> &Semaphore {
+        &self.sems[idx]
+    }
+}
+
+lazy_static! {
+    static ref KEY2SEM: RwLock<BTreeMap<usize, Weak<SemArray>>> = RwLock::new(BTreeMap::new());
+}
+
+impl SemArray {
+    /// Get the semaphore array with `key`.
+    /// If not exist, create a new one with `nsems` elements.
+    pub fn get_or_create(key: usize, nsems: usize, _flags: usize) -> Arc<Self> {
+        let mut key2sem = KEY2SEM.write();
+
+        // found in the map
+        if let Some(weak_array) = key2sem.get(&key) {
+            if let Some(array) = weak_array.upgrade() {
+                return array;
+            }
+        }
+        // not found, create one
+        let mut semaphores = Vec::new();
+        for i in 0..nsems {
+            semaphores.push(Semaphore::new(0));
+        }
+        // insert to global map
+        let array = Arc::new(SemArray {
+            key,
+            sems: semaphores,
+        });
+        key2sem.insert(key, Arc::downgrade(&array));
+        array
+    }
+}

kernel/src/lib.rs

@@ -32,6 +32,7 @@ pub mod backtrace;
 pub mod consts;
 pub mod drivers;
 pub mod fs;
+pub mod ipc;
 pub mod lang;
 pub mod lkm;
 pub mod memory;

kernel/src/process/structs.rs

@@ -14,6 +14,7 @@ use xmas_elf::{
 
 use crate::arch::interrupt::{Context, TrapFrame};
 use crate::fs::{FileHandle, FileLike, OpenOptions, FOLLOW_MAX_DEPTH};
+use crate::ipc::SemProc;
 use crate::memory::{
     ByFrame, Delay, File, GlobalFrameAlloc, KernelStack, MemoryAttr, MemorySet, Read,
 };
@@ -64,6 +65,7 @@ pub struct Process {
     pub cwd: String,
     pub exec_path: String,
     futexes: BTreeMap<usize, Arc<Condvar>>,
+    pub semaphores: SemProc,
 
     // relationship
     pub pid: Pid, // i.e. tgid, usually the tid of first thread
@@ -124,6 +126,7 @@ impl Thread {
                 files: BTreeMap::default(),
                 cwd: String::from("/"),
                 exec_path: String::new(),
+                semaphores: SemProc::default(),
                 futexes: BTreeMap::default(),
                 pid: Pid(0),
                 parent: Weak::new(),
@@ -308,6 +311,7 @@ impl Thread {
                 cwd: String::from("/"),
                 exec_path: String::from(exec_path),
                 futexes: BTreeMap::default(),
+                semaphores: SemProc::default(),
                 pid: Pid(0),
                 parent: Weak::new(),
                 children: Vec::new(),
@@ -334,6 +338,7 @@ impl Thread {
             cwd: proc.cwd.clone(),
             exec_path: proc.exec_path.clone(),
             futexes: BTreeMap::default(),
+            semaphores: proc.semaphores.clone(),
             pid: Pid(0),
             parent: Arc::downgrade(&self.proc),
             children: Vec::new(),
@@ -409,6 +414,7 @@ impl Process {
         }
         self.futexes.get(&uaddr).unwrap().clone()
     }
+
     /// Exit the process.
     /// Kill all threads and notify parent with the exit code.
     pub fn exit(&mut self, exit_code: usize) {

kernel/src/sync/semaphore.rs

@@ -61,6 +61,42 @@ impl Semaphore {
         self.acquire();
         SemaphoreGuard { sem: self }
     }
+
+    /// Get the current count
+    pub fn get(&self) -> isize {
+        let mut count = self.lock.lock();
+        *count
+    }
+
+    /// Set the current count
+    pub fn set(&self, value: isize) {
+        let mut count = self.lock.lock();
+        *count = value;
+    }
+
+    /// Modify by k atomically. when wait is false avoid waiting. unused
+    pub fn modify(&self, k: isize, wait: bool) -> Result<usize, ()> {
+        if k > 0 {
+            *(self.lock.lock()) += k;
+            self.cvar.notify_one();
+        } else if k <= 0 {
+            let mut count = self.lock.lock();
+            let mut temp_k = k;
+            while *count + temp_k < 0 {
+                if wait == false {
+                    return Err(());
+                }
+                temp_k += *count;
+                *count = 0;
+                count = self.cvar.wait(count);
+            }
+            *count += temp_k;
+            if *count > 0 {
+                self.cvar.notify_one();
+            }
+        }
+        Ok(0)
+    }
 }
 
 impl<'a> Drop for SemaphoreGuard<'a> {

kernel/src/syscall/ipc.rs

@@ -0,0 +1,94 @@
+use crate::sync::Semaphore;
+use crate::sync::SpinLock as Mutex;
+use alloc::{boxed::Box, collections::BTreeMap, string::String, sync::Arc, sync::Weak, vec::Vec};
+use bitflags::*;
+use core::cell::UnsafeCell;
+use spin::RwLock;
+
+pub use crate::ipc::*;
+
+use super::*;
+
+impl Syscall<'_> {
+    pub fn sys_semget(&self, key: usize, nsems: isize, flags: usize) -> SysResult {
+        info!("semget: key: {}", key);
+
+        /// The maximum semaphores per semaphore set
+        const SEMMSL: usize = 256;
+
+        if nsems < 0 || nsems as usize > SEMMSL {
+            return Err(SysError::EINVAL);
+        }
+        let nsems = nsems as usize;
+
+        let sem_array = SemArray::get_or_create(key, nsems, flags);
+        let id = self.process().semaphores.add(sem_array);
+        Ok(id)
+    }
+
+    pub fn sys_semop(&self, id: usize, ops: *const SemBuf, num_ops: usize) -> SysResult {
+        info!("semop: id: {}", id);
+        let ops = unsafe { self.vm().check_read_array(ops, num_ops)? };
+
+        let sem_array = self.process().semaphores.get(id).ok_or(SysError::EINVAL)?;
+        for &SemBuf { num, op, flags } in ops.iter() {
+            let flags = SemFlags::from_bits_truncate(flags);
+            if flags.contains(SemFlags::IPC_NOWAIT) {
+                unimplemented!("Semaphore: semop.IPC_NOWAIT");
+            }
+            let sem = &sem_array[num as usize];
+
+            let _result = match op {
+                1 => sem.release(),
+                -1 => sem.acquire(),
+                _ => unimplemented!("Semaphore: semop.(Not 1/-1)"),
+            };
+            if flags.contains(SemFlags::SEM_UNDO) {
+                self.process().semaphores.add_undo(id, num, op);
+            }
+        }
+        Ok(0)
+    }
+
+    pub fn sys_semctl(&self, id: usize, num: usize, cmd: usize, arg: isize) -> SysResult {
+        info!("semctl: id: {}, num: {}, cmd: {}", id, num, cmd);
+        let sem_array = self.process().semaphores.get(id).ok_or(SysError::EINVAL)?;
+        let sem = &sem_array[num as usize];
+
+        const GETVAL: usize = 12;
+        const GETALL: usize = 13;
+        const SETVAL: usize = 16;
+        const SETALL: usize = 17;
+
+        match cmd {
+            SETVAL => sem.set(arg),
+            _ => unimplemented!("Semaphore: Semctl.(Not setval)"),
+        }
+        Ok(0)
+    }
+}
+
+/// An operation to be performed on a single semaphore
+///
+/// Ref: [http://man7.org/linux/man-pages/man2/semop.2.html]
+#[repr(C)]
+pub struct SemBuf {
+    num: u16,
+    op: i16,
+    flags: i16,
+}
+
+pub union SemctlUnion {
+    val: isize,
+    buf: usize,   // semid_ds*, unimplemented
+    array: usize, // short*, unimplemented
+} // unused
+
+bitflags! {
+    pub struct SemFlags: i16 {
+        /// For SemOP
+        const IPC_NOWAIT = 0x800;
+        /// it will be automatically undone when the process terminates.
+        const SEM_UNDO = 0x1000;
+    }
+}

kernel/src/syscall/mod.rs

@@ -18,6 +18,7 @@ use crate::util;
 
 pub use self::custom::*;
 pub use self::fs::*;
+pub use self::ipc::*;
 pub use self::lkm::*;
 pub use self::mem::*;
 pub use self::misc::*;
@@ -27,6 +28,7 @@ pub use self::time::*;
 
 mod custom;
 mod fs;
+mod ipc;
 mod lkm;
 mod mem;
 mod misc;
@@ -259,6 +261,14 @@ impl Syscall<'_> {
             }
             SYS_CLOCK_GETTIME => self.sys_clock_gettime(args[0], args[1] as *mut TimeSpec),
 
+            // sem
+            #[cfg(not(target_arch = "mips"))]
+            SYS_SEMGET => self.sys_semget(args[0], args[1] as isize, args[2]),
+            #[cfg(not(target_arch = "mips"))]
+            SYS_SEMOP => self.sys_semop(args[0], args[1] as *const SemBuf, args[2]),
+            #[cfg(not(target_arch = "mips"))]
+            SYS_SEMCTL => self.sys_semctl(args[0], args[1], args[2], args[3] as isize),
+
             // system
             SYS_GETPID => self.sys_getpid(),
             SYS_GETTID => self.sys_gettid(),
@@ -398,6 +408,12 @@ impl Syscall<'_> {
                 }
                 Ok(0)
             }
+            SYS_IPC => match args[0] {
+                1 => self.sys_semop(args[1], args[2] as *const SemBuf, args[3]),
+                2 => self.sys_semget(args[1], args[2] as isize, args[3]),
+                3 => self.sys_semctl(args[1], args[2], args[3], args[4] as isize),
+                _ => return None,
+            },
             _ => return None,
         };
         Some(ret)

kernel/src/syscall/proc.rs

@@ -277,6 +277,7 @@ impl Syscall<'_> {
                 queue.notify_one();
             }
         }
+
         drop(proc);
 
         processor().manager().exit(tid, exit_code as usize);

rboot

@@ -1 +1 @@
-Subproject commit 3546cf87ee5aaefc638e6009262358fe07af8717
+Subproject commit 5aae6587f635f9eabd8f4643f381aa48cf597131

user

@@ -1 +1 @@
-Subproject commit 72a9ae029e90a39a32d14758b20365557ca0bfa5
+Subproject commit 3ae3a840bf39bbd6628892842688c8720273546d