Add alt-stack registration support

(Apply commit ff4ec56 from 'mono_libgc' branch.)

Fix altstack support in libgc by registering the bounds of the normal
stack and the altstack with it.

* darwin_stop_world.c (GC_stack_range_for): Add paltstack_lo,
paltstack_hi argments; set *paltstack_lo, *paltstack_hi, adjust lo and
hi if p->altstack set.
* darwin_stop_world.c (GC_push_all_stacks): Declare altstack_lo,
altstack_hi local variables; pass &altstack_lo, &altstack_hi to
GC_stack_range_for; do not call GC_push_all_stack(lo, hi) and
adjust total_size by hi-lo if lo is NULL; call
GC_push_all_stack(altstack_lo, altstack_hi) and increment total_size
by altstack_hi-altstack_lo if altstack_lo is non-NULL.
* include/gc.h (GC_register_altstack): New API function declaration.
* include/private/pthread_support.h (GC_Thread_Rep): Add altstack,
altstack_size, stack, stack_size fields.
* pthread_stop_world.c (GC_push_all_stacks): Adjust hi value if
p->altstack set.
* pthread_support.c (main_pthread_self, main_stack, main_altstack,
main_stack_size, main_altstack_size): New static variables.
* pthread_support.c (GC_register_altstack): New function.
* pthread_support.c (GC_thr_init): Set altstack, altstack_size, stack,
stack_size fields from values saved by GC_register_altstack (if called
before GC_thr_init).
* win32_threads.c (GC_register_altstack): New function (unimplemented).

1 files changed, 34 insertions, 10 deletions

diff --git a/darwin_stop_world.c b/darwin_stop_world.c
index 718e2f5c..23979035 100644
--- a/darwin_stop_world.c
+++ b/darwin_stop_world.c
@@ -129,7 +129,8 @@ GC_API void GC_CALL GC_use_threads_discovery(void)
 /* Evaluates the stack range for a given thread.  Returns the lower     */
 /* bound and sets *phi to the upper one.                                */
 STATIC ptr_t GC_stack_range_for(ptr_t *phi, thread_act_t thread, GC_thread p,
-                                GC_bool thread_blocked, mach_port_t my_thread)
+                                GC_bool thread_blocked, mach_port_t my_thread,
+                                ptr_t *paltstack_lo, ptr_t *paltstack_hi)
 {
   ptr_t lo;
   if (thread == my_thread) {
@@ -302,6 +303,16 @@ STATIC ptr_t GC_stack_range_for(ptr_t *phi, thread_act_t thread, GC_thread p,
     /* p is guaranteed to be non-NULL regardless of GC_query_task_threads. */
     *phi = (p->flags & MAIN_THREAD) != 0 ? GC_stackbottom : p->stack_end;
 # endif
+
+      if (p->altstack && lo >= p->altstack && lo <= p->altstack + p->altstack_size) {
+          *paltstack_lo = lo;
+          *paltstack_hi = p->altstack + p->altstack_size;
+          lo = (char*)p->stack;
+          *phi = (char*)p->stack + p->stack_size;
+      } else {
+          *paltstack_lo = NULL;
+      }
+
 # ifdef DEBUG_THREADS
     GC_log_printf("Darwin: Stack for thread %p = [%p,%p)\n",
                   (void *)thread, lo, *phi);
@@ -312,7 +323,7 @@ STATIC ptr_t GC_stack_range_for(ptr_t *phi, thread_act_t thread, GC_thread p,
 GC_INNER void GC_push_all_stacks(void)
 {
   int i;
-  ptr_t lo, hi;
+  ptr_t lo, hi, altstack_lo, altstack_hi;
   task_t my_task = current_task();
   mach_port_t my_thread = mach_thread_self();
   GC_bool found_me = FALSE;
@@ -334,10 +345,17 @@ GC_INNER void GC_push_all_stacks(void)
 
       for (i = 0; i < (int)listcount; i++) {
         thread_act_t thread = act_list[i];
-        lo = GC_stack_range_for(&hi, thread, NULL, FALSE, my_thread);
-        GC_ASSERT((word)lo <= (word)hi);
-        total_size += hi - lo;
-        GC_push_all_stack(lo, hi);
+        lo = GC_stack_range_for(&hi, thread, NULL, FALSE, my_thread,
+                                &altstack_lo, &altstack_hi);
+        if (lo) {
+          GC_ASSERT((word)lo <= (word)hi);
+          total_size += hi - lo;
+            GC_push_all_stack(lo,hi);
+        }
+        if (altstack_lo) {
+          total_size += altstack_hi - altstack_lo;
+            GC_push_all_stack(altstack_lo,altstack_hi);
+        }
         nthreads++;
         if (thread == my_thread)
           found_me = TRUE;
@@ -355,10 +373,16 @@ GC_INNER void GC_push_all_stacks(void)
         if ((p->flags & FINISHED) == 0) {
           thread_act_t thread = (thread_act_t)p->stop_info.mach_thread;
           lo = GC_stack_range_for(&hi, thread, p, (GC_bool)p->thread_blocked,
-                                  my_thread);
-          GC_ASSERT((word)lo <= (word)hi);
-          total_size += hi - lo;
-          GC_push_all_stack_sections(lo, hi, p->traced_stack_sect);
+                                  my_thread, &altstack_lo, &altstack_hi);
+          if (lo) {
+            GC_ASSERT((word)lo <= (word)hi);
+            total_size += hi - lo;
+            GC_push_all_stack_sections(lo, hi, p->traced_stack_sect);
+          }
+          if (altstack_lo) {
+            total_size += altstack_hi - altstack_lo;
+            GC_push_all_stack(altstack_lo, altstack_hi);
+          }
           nthreads++;
           if (thread == my_thread)
             found_me = TRUE;