Auto-drop processes, and added delete process.

risc_v/src/page.rs

@@ -54,23 +54,13 @@ impl Page {
 	// If this page has been marked as the final allocation,
 	// this function returns true. Otherwise, it returns false.
 	pub fn is_last(&self) -> bool {
-		if self.flags & PageBits::Last.val() != 0 {
+		self.flags & PageBits::Last.val() != 0
-			true
-		}
-		else {
-			false
-		}
 	}
 
 	// If the page is marked as being taken (allocated), then
 	// this function returns true. Otherwise, it returns false.
 	pub fn is_taken(&self) -> bool {
-		if self.flags & PageBits::Taken.val() != 0 {
+		self.flags & PageBits::Taken.val() != 0
-			true
-		}
-		else {
-			false
-		}
 	}
 
 	// This is the opposite of is_taken().
@@ -221,6 +211,8 @@ pub fn dealloc(ptr: *mut u8) {
 		// calculate here is the page structure, not the HEAP address!
 		assert!(addr >= HEAP_START && addr < ALLOC_START);
 		let mut p = addr as *mut Page;
+		// println!("PTR in is {:p}, addr is 0x{:x}", ptr, addr);
+		assert!((*p).is_taken(), "Freeing a non-taken page?");
 		// Keep clearing pages until we hit the last page.
 		while (*p).is_taken() && !(*p).is_last() {
 			(*p).clear();

risc_v/src/process.rs

@@ -85,6 +85,26 @@ pub fn set_waiting(pid: u16) -> bool {
 	retval
 }
 
+pub fn delete_process(pid: u16) {
+	unsafe {
+		if let Some(mut pl) = PROCESS_LIST.take() {
+			for i in 0..pl.len() {
+				let p = pl.get_mut(i).unwrap();
+				if p.get_pid() == pid {
+					// When the structure gets dropped, all of the
+					// allocations get deallocated.
+					pl.remove(i);
+					break;
+				}
+			}
+			// Now, we no longer need the owned Deque, so we hand it
+			// back by replacing the PROCESS_LIST's None with the
+			// Some(pl).
+			PROCESS_LIST.replace(pl);
+		}
+	}
+}
+
 /// We will eventually move this function out of here, but its
 /// job is just to take a slot in the process list.
 fn init_process() {
@@ -153,7 +173,7 @@ pub fn add_kernel_process(func: fn()) {
 			    // we start getting into multi-hart processing. For now, we want
 			    // a process. Get it to work, then improve it!
 		let mut ret_proc = Process { frame:       zalloc(1) as *mut TrapFrame,
-		                             stack:       alloc(STACK_PAGES),
+		                             stack:       zalloc(STACK_PAGES),
 		                             pid:         unsafe { NEXT_PID },
 		                             root:        zalloc(1) as *mut Table,
 		                             state:       ProcessState::Running,
@@ -340,6 +360,7 @@ impl Drop for Process {
 	/// Since we're storing ownership of a Process in the linked list,
 	/// we can cause it to deallocate automatically when it is removed.
 	fn drop(&mut self) {
+		// println!("Dropping process {}", self.get_pid());
 		// We allocate the stack as a page.
 		dealloc(self.stack);
 		// This is unsafe, but it's at the drop stage, so we won't
@@ -351,6 +372,7 @@ impl Drop for Process {
 			unmap(&mut *self.root);
 		}
 		dealloc(self.root as *mut u8);
+		dealloc(self.frame as *mut u8);
 	}
 }
 

risc_v/src/syscall.rs

@@ -4,6 +4,7 @@
 // 3 Jan 2020
 
 use crate::{block::process_read, cpu::TrapFrame};
+use crate::process::delete_process;
 
 pub fn do_syscall(mepc: usize, frame: *mut TrapFrame) -> usize {
 	let syscall_number;
@@ -62,12 +63,13 @@ pub fn do_syscall(mepc: usize, frame: *mut TrapFrame) -> usize {
 	// #define SYS_time 1062
 	// #define SYS_getmainvars 2011
 	match syscall_number {
-		0 | 93 => {
+		0 | 93 => unsafe {
 			// Exit
 			// Currently, we cannot kill a process, it runs forever. We will delete
 			// the process later and free the resources, but for now, we want to get
-			// used to how processes will be scheduled on the CPU.
+            // used to how processes will be scheduled on the CPU.
-			mepc + 4
+            delete_process((*frame).pid as u16);
+			0
 		},
 		1 => {
 			println!("Test syscall");
@@ -77,6 +79,8 @@ pub fn do_syscall(mepc: usize, frame: *mut TrapFrame) -> usize {
 			// Read system call
 			// This is an asynchronous call. This will get the process going. We won't hear the answer until
             // we an interrupt back.
+            // TODO: The buffer is a virtual memory address that needs to be translated to a physical memory
+            // location.
 			let _ = process_read(
 			                     (*frame).pid as u16,
 			                     (*frame).regs[10],

risc_v/src/test.rs

@@ -18,10 +18,15 @@ pub fn test_block() {
         make_syscall(63, 8, buffer as usize, 1024, 1024);
         for i in 0..32 {
             print!("{:02x}  ", buffer.add(i).read());
+            if (i+1) % 16 == 0 {
+                println!();
+            }
         }
     }
     println!();
     crate::kmem::kfree(buffer);
     println!("Test block finished");
-    loop {}
+    unsafe {
+        make_syscall(93, 0, 0, 0, 0);
+    }
 }