Added a library version of spawn. Before long, we can remove the old version.

Author: Eric Holk

src/lib/task.rs

@@ -1,3 +1,5 @@
+import cast = unsafe::reinterpret_cast;
+
 native "rust" mod rustrt {
     fn task_sleep(time_in_us: uint);
     fn task_yield();
@@ -9,8 +11,15 @@ native "rust" mod rustrt {
     fn clone_chan(c: *rust_chan) -> *rust_chan;
 
     type rust_chan;
+    type rust_task;
 
     fn set_min_stack(stack_size: uint);
+
+    fn new_task() -> task_id;
+    fn get_task_pointer(id : task_id) -> *rust_task;
+    fn get_task_context(id : task_id) -> *x86_registers;
+    fn start_task(id : task_id);
+    fn get_task_trampoline() -> u32;
 }
 
 type task_id = int;
@@ -54,6 +63,76 @@ fn set_min_stack(stack_size : uint) {
     rustrt::set_min_stack(stack_size);
 }
 
+// FIXME: make this a fn~ once those are supported.
+fn _spawn(thunk : -fn() -> ()) -> task_id {
+    let id = rustrt::new_task();
+
+    // the order of arguments are outptr, taskptr, envptr.
+
+    // In LLVM fastcall puts the first two in ecx, edx, and the rest on the
+    // stack.
+    let regs = rustrt::get_task_context(id);
+
+    // set up the task pointer
+    let task_ptr : u32 = cast(rustrt::get_task_pointer(id));
+    (*regs).edx = task_ptr;
+
+    let raw_thunk : { code: u32, env: u32 } = cast(thunk);
+    (*regs).eip = raw_thunk.code;
+
+    log_err #fmt("{ %u, %u }", raw_thunk.code as uint, raw_thunk.env as uint);
+
+    // okay, now we align the stack and add the environment pointer and a fake
+    // return address.
+
+    // -12 for the taskm output location, the env pointer
+    // -4 for the return address.
+    (*regs).esp = align_down((*regs).esp - 12u32) - 4u32;
+
+    let ra : *mutable u32 = cast((*regs).esp);
+    let env : *mutable u32 = cast((*regs).esp+4u32);
+    let tptr : *mutable u32 = cast((*regs).esp+12u32);
+
+    // put the return pointer in ecx.
+    (*regs).ecx = (*regs).esp + 8u32;
+
+    *tptr = task_ptr;
+    *env = raw_thunk.env;
+    *ra = rustrt::get_task_trampoline();
+
+    rustrt::start_task(id);
+
+    ret id;
+}
+
+// Who says we can't write an operating system in Rust?
+type x86_registers = {
+    // This needs to match the structure in context.h
+    mutable eax : u32,
+    mutable ebx : u32,
+    mutable ecx : u32,
+    mutable edx : u32,
+    mutable ebp : u32,
+    mutable esi : u32,
+    mutable edi : u32,
+    mutable esp : u32,
+
+    mutable cs : u16,
+    mutable ds : u16,
+    mutable ss : u16,
+    mutable es : u16,
+    mutable fs : u16,
+    mutable gs : u16,
+
+    mutable eflags : u32,
+    mutable eip : u32
+};
+
+fn align_down(x : u32) -> u32 {
+    // Aligns x down to 16 bytes
+    x & !(15u32)
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;

src/rt/arch/i386/_context.s

@@ -22,17 +22,17 @@ swap_registers:
     movl 4(%esp), %eax
 	//movl %eax, 0(%eax)
 	movl %ebx, 4(%eax)
-	//movl %ecx, 8(%eax)
-	//movl %edx, 12(%eax)
+	movl %ecx, 8(%eax)
+	movl %edx, 12(%eax)
 	movl %ebp, 16(%eax)
 	movl %esi, 20(%eax)
 	movl %edi, 24(%eax)
-	movw %cs, 32(%eax)
-	movw %ds, 34(%eax)
-	movw %ss, 36(%eax)
-	movw %es, 38(%eax)
-	movw %fs, 40(%eax)
-	movw %gs, 42(%eax)
+	//movl %cs, 32(%eax)
+	//movl %ds, 34(%eax)
+	//movl %ss, 36(%eax)
+	//movl %es, 38(%eax)
+	//movl %fs, 40(%eax)
+	//movl %gs, 42(%eax)
 
 	// save the flags
 	pushf
@@ -50,23 +50,32 @@ swap_registers:
 
 	movl 4(%eax), %ebx
 	// save ecx for later...
-	//movl 12(%eax), %edx
+	movl 12(%eax), %edx
 	movl 16(%eax), %ebp
 	movl 20(%eax), %esi
 	movl 24(%eax), %edi
 	movl 28(%eax), %esp
 	// We can't actually change this...
 	//movl 32(%eax), %cs
-	movw 34(%eax), %ds
-	movw 36(%eax), %ss
-	movw 38(%eax), %es
-	movw 40(%eax), %fs
-	movw 42(%eax), %gs
+	//movl 34(%eax), %ds
+	//movl 36(%eax), %ss
+	//movl 38(%eax), %es
+	//movl 40(%eax), %fs
+	//movl 42(%eax), %gs
 
 	// restore the flags
 	movl 44(%eax), %ecx
 	push %ecx
 	popf
 
+    // ok, now we can restore ecx
+    movl 8(%eax), %ecx
+	
     // Return!
     jmp *48(%eax)
+
+
+.globl task_trampoline
+task_trampoline:
+    // This gets set up by std::task::_spawn.
+    call _task_exit

src/rt/arch/i386/context.h

@@ -18,9 +18,9 @@ struct registers_t {
 };
 
 class context {
+public:
   registers_t regs;
 
-public:
   context();
 
   context *next;

src/rt/rust_builtin.cpp

@@ -707,6 +707,37 @@ get_task_id(rust_task *task) {
     return task->id;
 }
 
+extern "C" CDECL rust_task_id
+new_task(rust_task *task) {
+    return task->kernel->create_task(task, NULL);
+}
+
+extern "C" CDECL registers_t *
+get_task_context(rust_task *task, rust_task_id id) {
+    registers_t *regs = &task->kernel->get_task_by_id(id)->ctx.regs;
+    // This next line is a little dangerous.. It means we can only safely call
+    // this when starting a task.
+    regs->esp = task->rust_sp;
+    return regs;
+}
+
+extern "C" CDECL rust_task *
+get_task_pointer(rust_task *task, rust_task_id id) {
+    return task->kernel->get_task_by_id(id);
+}
+
+extern "C" CDECL void
+start_task(rust_task *task, rust_task_id id) {
+    task->kernel->get_task_by_id(id)->start();
+}
+
+extern "C" void *task_trampoline asm("task_trampoline");
+
+extern "C" CDECL void **
+get_task_trampoline(rust_task *task) {
+    return &task_trampoline;
+}
+
 extern "C" CDECL rust_chan *
 clone_chan(rust_task *task, rust_chan *chan) {
     return chan->clone(task);

src/rt/rust_task.cpp

@@ -52,13 +52,6 @@ del_stk(rust_task *task, stk_seg *stk)
 }
 
 // Tasks
-
-// FIXME (issue #31): ifdef by platform. This is getting absurdly
-// x86-specific.
-
-size_t const n_callee_saves = 4;
-size_t const callee_save_fp = 0;
-
 rust_task::rust_task(rust_scheduler *sched, rust_task_list *state,
                      rust_task *spawner, const char *name) :
     ref_count(1),
@@ -115,15 +108,8 @@ struct spawn_args {
 };
 
 extern "C" CDECL
-void task_start_wrapper(spawn_args *a)
-{
-    rust_task *task = a->task;
-    int rval = 42;
-
-    a->f(&rval, task, a->a3, a->a4);
-
+void task_exit(void *env, int rval, rust_task *task) {
     LOG(task, task, "task exited with value %d", rval);
-
     task->die();
     task->lock.lock();
     task->notify_tasks_waiting_to_join();
@@ -132,6 +118,16 @@ void task_start_wrapper(spawn_args *a)
     task->yield(1);
 }
 
+extern "C" CDECL
+void task_start_wrapper(spawn_args *a)
+{
+    rust_task *task = a->task;
+    int rval = 42;
+
+    a->f(&rval, task, a->a3, a->a4);
+    task_exit(NULL, rval, task);
+}
+
 void
 rust_task::start(uintptr_t spawnee_fn,
                  uintptr_t args)
@@ -154,6 +150,11 @@ rust_task::start(uintptr_t spawnee_fn,
 
     ctx.call((void *)task_start_wrapper, a, sp);
 
+    this->start();
+}
+
+void rust_task::start()
+{
     yield_timer.reset_us(0);
     transition(&sched->newborn_tasks, &sched->running_tasks);
     sched->lock.signal();

src/rt/rust_task.h

@@ -109,6 +109,7 @@ rust_task : public kernel_owned<rust_task>, rust_cond
 
     void start(uintptr_t spawnee_fn,
                uintptr_t args);
+    void start();
     void grow(size_t n_frame_bytes);
     bool running();
     bool blocked();

src/rt/rustrt.def.in

@@ -27,7 +27,10 @@ do_gc
 drop_chan
 drop_port
 get_port_id
+get_task_context
 get_task_id
+get_task_pointer
+get_task_trampoline
 get_time
 hack_allow_leaks
 ivec_copy_from_buf
@@ -40,6 +43,7 @@ last_os_error
 nano_time
 new_chan
 new_port
+new_task
 pin_task
 port_recv
 unpin_task
@@ -61,6 +65,7 @@ set_min_stack
 sched_threads
 size_of
 squareroot
+start_task
 str_alloc
 str_buf
 str_byte_len

src/test/stdtest/task.rs

@@ -33,3 +33,8 @@ fn test_send_recv() {
     assert (task::recv(p) == 10);
 }
 
+#[test]
+fn test_lib_spawn() {
+    fn foo() { log_err "Hello, World!"; }
+    task::_spawn(foo);
+}