Support task_wait / task_wait_tid syscalls:

    - Add task_end2 syscall to allow pthread_exit-like retval.
    - Add/maintain task states.
    - Create task parent/child tracking tree.
    - Add task_detach function.
    - Implement wait syscalls.

Make task_exec caller the parent of spawned task:

    Previously the task_exec call caused a message to the
    VFS task, which called task_create and returned the tid
    in response to the message.  This causes the parent of
    the spawned task to appear to be the VFS task.

    Modify task_exec / VFS handling to instead return the
    entry point address on the message and have task_exec call
    task_create directly itself.

Change-Id: I6b6796f45875de37b1ab01e7596639b073820b95
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/443
Tested-by: Jenkins Server
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Reviewed-by: Andrew J. Geissler <andrewg@us.ibm.com>

2 files changed, 75 insertions, 15 deletions

diff --git a/src/lib/syscall_stub.S b/src/lib/syscall_stub.S
index aca533338..6c839346c 100644
--- a/src/lib/syscall_stub.S
+++ b/src/lib/syscall_stub.S
@@ -1,24 +1,24 @@
 #   IBM_PROLOG_BEGIN_TAG
 #   This is an automatically generated prolog.
-# 
+#
 #   $Source: src/lib/syscall_stub.S $
-# 
+#
 #   IBM CONFIDENTIAL
-# 
+#
 #   COPYRIGHT International Business Machines Corp. 2010 - 2011
-# 
+#
 #   p1
-# 
+#
 #   Object Code Only (OCO) source materials
 #   Licensed Internal Code Source Materials
 #   IBM HostBoot Licensed Internal Code
-# 
+#
 #   The source code for this program is not published or other-
 #   wise divested of its trade secrets, irrespective of what has
 #   been deposited with the U.S. Copyright Office.
-# 
+#
 #   Origin: 30
-# 
+#
 #   IBM_PROLOG_END
 .section .text
 
@@ -41,3 +41,24 @@ _syscall6:
 _syscall7:
     sc
     blr
+
+.global _syscall0_nr
+.global _syscall1_nr
+.global _syscall2_nr
+.global _syscall3_nr
+.global _syscall4_nr
+.global _syscall5_nr
+.global _syscall6_nr
+.global _syscall7_nr
+
+_syscall0_nr:
+_syscall1_nr:
+_syscall2_nr:
+_syscall3_nr:
+_syscall4_nr:
+_syscall5_nr:
+_syscall6_nr:
+_syscall7_nr:
+    sc
+1:
+    b 1b
diff --git a/src/lib/syscall_task.C b/src/lib/syscall_task.C
index 38b8adee4..a00b779f7 100644
--- a/src/lib/syscall_task.C
+++ b/src/lib/syscall_task.C
@@ -49,8 +49,12 @@ tid_t task_create(void(*fn)(void*), void* ptr)
 
 void task_end()
 {
-    _syscall0(TASK_END); // no return.
-    return;
+    _syscall1_nr(TASK_END, NULL); // no return.
+}
+
+void task_end2(void* retval)
+{
+    _syscall1_nr(TASK_END, retval); // no return.
 }
 
 tid_t task_gettid()
@@ -69,8 +73,8 @@ cpuid_t task_getcpuid()
 
 tid_t task_exec(const char* file, void* ptr)
 {
-    // The VFS process is responsible for finding the module and creating the
-    // new process.  So, we send a message over to that process.
+    // The VFS process is responsible for finding the module and entry point
+    // address, so we send a message over to that process.
 
     tid_t child = 0;
     int rc = 0;
@@ -80,7 +84,6 @@ tid_t task_exec(const char* file, void* ptr)
     msg_t* msg = msg_allocate();
     msg->type = VFS_MSG_EXEC;
     msg->data[0] = (uint64_t) file;
-    msg->data[1] = (uint64_t) ptr;
     if (vfsQ)
     {
         msg_sendrecv(vfsQ, msg);
@@ -93,8 +96,17 @@ tid_t task_exec(const char* file, void* ptr)
 
     if (0 == rc)
     {
-        // Get child ID from message data 0.
-        child = (tid_t) msg->data[0];
+        // Get fn ptr or error from message data 0.
+        int64_t value = *reinterpret_cast<int64_t*>(&msg->data[0]);
+        if (value < 0)
+        {
+            child = value;
+        }
+        else
+        {
+            child = task_create(reinterpret_cast<void(*)(void*)>(msg->data[0]),
+                                ptr);
+        }
     }
     else
     {
@@ -129,3 +141,30 @@ void task_affinity_migrate_to_master()
 {
     _syscall0(TASK_MIGRATE_TO_MASTER);
 }
+
+void task_detach()
+{
+    // Get task structure.
+    register task_t* task;
+    asm volatile("mr %0, 13" : "=r"(task));
+
+    task->detached = true;
+        // This does not need any sync instruction because the setting is
+        // only used by the kernel and it requires a context-sync operation
+        // to enter kernel mode.
+}
+
+tid_t task_wait_tid(tid_t tid, int* status, void** retval)
+{
+    return static_cast<tid_t>(
+               reinterpret_cast<uint64_t>(
+                   _syscall3(TASK_WAIT,(void*)tid,status,retval)));
+}
+
+tid_t task_wait(int* status, void** retval)
+{
+    return static_cast<tid_t>(
+               reinterpret_cast<uint64_t>(
+                   _syscall3(TASK_WAIT,(void*)-1,status,retval)));
+}
+