Add a sys$exit and make init_stage2 call it when finished.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/3a3c57357c9

Kernel/Syscall.cpp

@@ -77,6 +77,10 @@ DWORD handle(DWORD function, DWORD arg1, DWORD arg2, DWORD arg3)
         return current->sys$kill((pid_t)arg1, (int)arg2);
     case Syscall::PosixGetuid:
         return current->sys$getuid();
+    case Syscall::PosixExit:
+        current->sys$exit((int)arg1);
+        ASSERT_NOT_REACHED();
+        return 0;
     default:
         kprintf("int0x80: Unknown function %x requested {%x, %x, %x}\n", function, arg1, arg2, arg3);
         break;

Kernel/Syscall.h

@@ -16,6 +16,7 @@ enum Function {
     PosixSeek = 0x1988,
     PosixKill = 0x1989,
     PosixGetuid = 0x1990,
+    PosixExit = 0x1991,
 };
 
 void initialize();
@@ -23,21 +24,21 @@ void initialize();
 inline DWORD invoke(DWORD function)
 {
     DWORD result;
-    asm("int $0x80":"=a"(result):"a"(function));
+    asm volatile("int $0x80":"=a"(result):"a"(function));
     return result;
 }
 
 inline DWORD invoke(DWORD function, DWORD arg1)
 {
     DWORD result;
-    asm("int $0x80":"=a"(result):"a"(function),"d"(arg1));
+    asm volatile("int $0x80":"=a"(result):"a"(function),"d"(arg1));
     return result;
 }
 
 inline DWORD invoke(DWORD function, DWORD arg1, DWORD arg2)
 {
     DWORD result;
-    asm("int $0x80":"=a"(result):"a"(function),"d"(arg1),"c"(arg2));
+    asm volatile("int $0x80":"=a"(result):"a"(function),"d"(arg1),"c"(arg2));
     return result;
 }
 

Kernel/Task.cpp

@@ -235,6 +235,26 @@ void Task::dumpRegions()
     }
 }
 
+void Task::sys$exit(int status)
+{
+    cli();
+    kprintf("sys$exit: %s(%u) exit with status %d\n", name().characters(), pid(), status);
+
+    setState(Exiting);
+    dumpRegions();
+
+    s_tasks->remove(this);
+
+    if (!scheduleNewTask()) {
+        kprintf("Task::taskDidCrash: Failed to schedule a new task :(\n");
+        HANG;
+    }
+
+    delete this;
+
+    switchNow();
+}
+
 void Task::taskDidCrash(Task* crashedTask)
 {
     // NOTE: This is called from an excepton handler, so interrupts are disabled.

Kernel/Task.h

@@ -31,6 +31,7 @@ public:
         BlockedSleep = 5,
         Terminated = 6,
         Crashing = 7,
+        Exiting = 8,
     };
 
     enum RingLevel {
@@ -83,6 +84,7 @@ public:
     int sys$kill(pid_t pid, int sig);
     int sys$geterror() { return m_error; }
     void sys$sleep(DWORD ticks);
+    void sys$exit(int status);
 
     struct
     {

Kernel/init.cpp

@@ -192,6 +192,11 @@ static void init_stage2()
 
     kprintf("init stage2 is done!\n");
 
+    DO_SYSCALL_A1(Syscall::PosixExit, 413);
+
+    kprintf("uh, we're still going after calling sys$exit...\n");
+    HANG;
+
     for (;;) {
         asm("hlt");
     }