Changeset 5c1a531

Timestamp:

Apr 11, 2019, 10:36:13 AM (6 years ago)

Author:

tdelisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, cleanup-dtors, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

3c06bba

Parents:

e8e457e

Message:

Fixed errno virtualization and enabled preemption during coroutine context switch

Location:

libcfa/src/concurrency

Files:

• coroutine.cfa (modified) (2 diffs)
• invoke.c (modified) (1 diff)
• invoke.h (modified) (2 diffs)
• kernel.cfa (modified) (5 diffs)

libcfa/src/concurrency/coroutine.cfa

@@ -126 +126 @@
 // Wrapper for co
 void CoroutineCtxSwitch(coroutine_desc* src, coroutine_desc* dst) {
-        // Safety note : Preemption must be disabled since there is a race condition
-        // kernelTLS.this_thread->curr_cor and $rsp/$rbp must agree at all times
-        verify( TL_GET( preemption_state.enabled ) || TL_GET( this_processor )->do_terminate );
-        disable_interrupts();
-
         // set state of current coroutine to inactive
         src->state = src->state == Halted ? Halted : Inactive;
@@ -144 +139 @@
         // set state of new coroutine to active
         src->state = Active;
-
-        enable_interrupts( __cfaabi_dbg_ctx );
-        verify( TL_GET( preemption_state.enabled ) || TL_GET( this_processor )->do_terminate );
 
         if( unlikely(src->cancellation != NULL) ) {

libcfa/src/concurrency/invoke.c

@@ -46 +46 @@
 
         cor->state = Active;
-
-        enable_interrupts( __cfaabi_dbg_ctx );
 
         main( this );

libcfa/src/concurrency/invoke.h

@@ -65 +65 @@
                 void * SP;
                 void * FP;
-                // copy of global UNIX variable errno
-                int errno_;
         };
 
@@ -168 +166 @@
                 // current execution status for coroutine
                 enum coroutine_state state;
+
+                //SKULLDUGGERY errno is not save in the thread data structure because returnToKernel appears to be the only function to require saving and restoring it
 
                 // coroutine body used to store context

libcfa/src/concurrency/kernel.cfa

@@ -91 +91 @@
 
 void ?{}( coroutine_desc & this, current_stack_info_t * info) with( this ) {
-        context.errno_ = 0;
         stack.storage = info->storage;
         with(*stack.storage) {
@@ -237 +236 @@
 }
 
+static int * __volatile_errno() __attribute__((noinline));
+static int * __volatile_errno() { asm(""); return &errno; }
+
 // KERNEL ONLY
 // runThread runs a thread by context switching
@@ -271 +273 @@
         thrd_src->state = thrd_src->state == Halted ? Halted : Inactive;
         proc_cor->state = Active;
+        int local_errno = *__volatile_errno();
 
         // set new coroutine that the processor is executing
@@ -280 +283 @@
         proc_cor->state = proc_cor->state == Halted ? Halted : Inactive;
         thrd_src->state = Active;
+        *__volatile_errno() = local_errno;
 }
 
@@ -380 +384 @@
         src->state = src->state == Halted ? Halted : Inactive;
 
-        // SKULLDUGGERY normally interrupts are enable before leaving a coroutine ctxswitch.
-        // Therefore, when first creating a coroutine, interrupts are enable before calling the main.
-        // This is consistent with thread creation. However, when creating the main processor coroutine,
-        // we wan't interrupts to be disabled. Therefore, we double-disable interrupts here so they will
-        // stay disabled.
-        disable_interrupts();
-
         // context switch to specified coroutine
         verify( dst->context.SP );