From 5b9c821ff5d1fbcf3c9f2b28ddcc5b936c694297 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Sat, 20 Aug 2016 14:32:45 -0600
Subject: [PATCH] Initialize contexts, add getpid

---
 kernel/context/mod.rs     | 18 ++++++++++++++----
 kernel/lib.rs             |  8 ++++++--
 kernel/syscall/mod.rs     |  6 +++++-
 kernel/syscall/process.rs | 13 ++++++++++++-
 4 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/kernel/context/mod.rs b/kernel/context/mod.rs
index 29aa094..30feb93 100644
--- a/kernel/context/mod.rs
+++ b/kernel/context/mod.rs
@@ -37,7 +37,7 @@ impl ContextList {
         self.map.get(&CONTEXT_ID.load(Ordering::SeqCst))
     }
 
-    pub fn new_context(&mut self) -> Result<(usize, &RwLock<Context>)> {
+    pub fn new_context(&mut self) -> Result<&RwLock<Context>> {
         if self.next_id >= CONTEXT_MAX_CONTEXTS {
             self.next_id = 1;
         }
@@ -52,8 +52,8 @@ impl ContextList {
 
         let id = self.next_id;
         self.next_id += 1;
-        assert!(self.map.insert(id, RwLock::new(Context::new())).is_none());
-        Ok((id, self.map.get(&id).expect("failed to insert new context")))
+        assert!(self.map.insert(id, RwLock::new(Context::new(id))).is_none());
+        Ok(self.map.get(&id).expect("failed to insert new context"))
     }
 }
 
@@ -63,6 +63,13 @@ static CONTEXTS: Once<RwLock<ContextList>> = Once::new();
 #[thread_local]
 static CONTEXT_ID: AtomicUsize = ATOMIC_USIZE_INIT;
 
+pub fn init() {
+    let mut contexts = contexts_mut();
+    let context_lock = contexts.new_context().expect("could not initialize first context");
+    let context = context_lock.read();
+    CONTEXT_ID.store(context.id, Ordering::SeqCst);
+}
+
 /// Initialize contexts, called if needed
 fn init_contexts() -> RwLock<ContextList> {
     RwLock::new(ContextList::new())
@@ -81,13 +88,16 @@ pub fn contexts_mut() -> RwLockWriteGuard<'static, ContextList> {
 /// A context, which identifies either a process or a thread
 #[derive(Debug)]
 pub struct Context {
+    /// The ID of this context
+    pub id: usize,
     /// The open files in the scheme
     pub files: Vec<Option<file::File>>
 }
 
 impl Context {
-    pub fn new() -> Context {
+    pub fn new(id: usize) -> Context {
         Context {
+            id: id,
             files: Vec::new()
         }
     }
diff --git a/kernel/lib.rs b/kernel/lib.rs
index 88ca1d0..a5aa1fe 100644
--- a/kernel/lib.rs
+++ b/kernel/lib.rs
@@ -112,7 +112,9 @@ pub mod tests;
 
 #[no_mangle]
 pub extern fn kmain() {
-    print!("{}", format!("BSP\n"));
+    context::init();
+
+    print!("{}", format!("BSP: {:?}\n", syscall::getpid()));
 
     loop {
         unsafe { interrupt::enable_and_halt(); }
@@ -121,7 +123,9 @@ pub extern fn kmain() {
 
 #[no_mangle]
 pub extern fn kmain_ap(id: usize) {
-    print!("{}", format!("AP {}\n", id));
+    context::init();
+
+    print!("{}", format!("AP {}: {:?}\n", id, syscall::getpid()));
 
     loop {
         unsafe { interrupt::enable_and_halt() }
diff --git a/kernel/syscall/mod.rs b/kernel/syscall/mod.rs
index edc924d..f42a431 100644
--- a/kernel/syscall/mod.rs
+++ b/kernel/syscall/mod.rs
@@ -28,6 +28,8 @@ pub enum Call {
     Close = 6,
     /// Execute syscall
     Exec = 11,
+    /// Get process ID
+    GetPid = 20,
 }
 
 /// Convert numbers to calls
@@ -41,6 +43,7 @@ impl Call {
             5 => Ok(Call::Open),
             6 => Ok(Call::Close),
             11 => Ok(Call::Exec),
+            20 => Ok(Call::GetPid),
             _ => Err(Error::NoCall)
         }
     }
@@ -90,7 +93,8 @@ pub fn handle(a: usize, b: usize, c: usize, d: usize, e: usize, _f: usize) -> Re
         Call::Write => write(b, convert_slice(c as *const u8, d)?),
         Call::Open => open(convert_slice(b as *const u8, c)?, d),
         Call::Close => close(b),
-        Call::Exec => exec(convert_slice(b as *const u8, c)?, convert_slice(d as *const [usize; 2], e)?)
+        Call::Exec => exec(convert_slice(b as *const u8, c)?, convert_slice(d as *const [usize; 2], e)?),
+        Call::GetPid => getpid(),
     }
 }
 
diff --git a/kernel/syscall/process.rs b/kernel/syscall/process.rs
index 6daf73a..4f43aee 100644
--- a/kernel/syscall/process.rs
+++ b/kernel/syscall/process.rs
@@ -2,7 +2,9 @@
 
 use arch::interrupt::halt;
 
-use super::{convert_slice, Result};
+use context;
+
+use super::{convert_slice, Error, Result};
 
 pub fn exit(status: usize) -> ! {
     println!("Exit {}", status);
@@ -19,3 +21,12 @@ pub fn exec(path: &[u8], args: &[[usize; 2]]) -> Result<usize> {
     println!("");
     Ok(0)
 }
+
+pub fn getpid() -> Result<usize> {
+    if let Some(context_lock) = context::contexts().current() {
+        let context = context_lock.read();
+        Ok(context.id)
+    } else {
+        Err(Error::NoProcess)
+    }
+}