erts: Align ErtsThrPrgrLaterOp when free'ing tracer

On Sparc all structs with a double word element in are assumed
to be allocated on a two word boundary. So we have to make sure
that the ErtsThrPrgrLaterOp * points to 8 / 16 byte aligned memory.
As it only costs one word I've done it on all architectures in case
some unknown other arch also needs this.

1 files changed, 15 insertions, 5 deletions

diff --git a/erts/emulator/beam/erl_trace.c b/erts/emulator/beam/erl_trace.c
index d14d237ca6..c4396488f5 100644
--- a/erts/emulator/beam/erl_trace.c
+++ b/erts/emulator/beam/erl_trace.c
@@ -3108,6 +3108,7 @@ erts_tracer_update(ErtsTracer *tracer, const ErtsTracer new_tracer)
     if (is_not_nil(*tracer)) {
         Uint offs = 2;
         UWord size = 2 * sizeof(Eterm) + sizeof(ErtsThrPrgrLaterOp);
+        ErtsThrPrgrLaterOp *lop;
         ASSERT(is_list(*tracer));
         if (is_not_immed(ERTS_TRACER_STATE(*tracer))) {
             hf = (void*)(((char*)(ptr_val(*tracer)) - offsetof(ErlHeapFragment, mem)));
@@ -3115,6 +3116,16 @@ erts_tracer_update(ErtsTracer *tracer, const ErtsTracer new_tracer)
             size = hf->alloc_size * sizeof(Eterm) + sizeof(ErlHeapFragment);
             ASSERT(offs == size_object(*tracer));
         }
+
+        /* sparc assumes that all structs are double word aligned, so we
+           have to align the ErtsThrPrgrLaterOp struct otherwise it may
+           segfault.*/
+        if ((UWord)(ptr_val(*tracer) + offs) % (sizeof(UWord)*2) == sizeof(UWord))
+            offs += 1;
+
+        lop = (ErtsThrPrgrLaterOp*)(ptr_val(*tracer) + offs);
+        ASSERT((UWord)lop % (sizeof(UWord)*2) == 0);
+
         /* We schedule the free:ing of the tracer until after a thread progress
            has been made so that we know that no schedulers have any references
            to it. Because we do this, it is possible to release all locks of a
@@ -3122,9 +3133,7 @@ erts_tracer_update(ErtsTracer *tracer, const ErtsTracer new_tracer)
            without having to worry if it is free'd.
         */
         erts_schedule_thr_prgr_later_cleanup_op(
-            free_tracer, (void*)(*tracer),
-            (ErtsThrPrgrLaterOp*)(ptr_val(*tracer) + offs),
-            size);
+            free_tracer, (void*)(*tracer), lop, size);
     }
 
     if (is_nil(new_tracer)) {
@@ -3141,9 +3150,10 @@ erts_tracer_update(ErtsTracer *tracer, const ErtsTracer new_tracer)
         Eterm *hp, tracer_state = ERTS_TRACER_STATE(new_tracer),
             tracer_module = ERTS_TRACER_MODULE(new_tracer);
         Uint sz = size_object(tracer_state);
-        hf = new_message_buffer(sz + 2  /* cons cell */ + (sizeof(ErtsThrPrgrLaterOp)+sizeof(Eterm)-1)/sizeof(Eterm));
+        hf = new_message_buffer(sz + 2  /* cons cell */ +
+                                (sizeof(ErtsThrPrgrLaterOp)+sizeof(Eterm)-1)/sizeof(Eterm) + 1);
         hp = hf->mem + 2;
-        hf->used_size -= (sizeof(ErtsThrPrgrLaterOp)+sizeof(Eterm)-1)/sizeof(Eterm);
+        hf->used_size -= (sizeof(ErtsThrPrgrLaterOp)+sizeof(Eterm)-1)/sizeof(Eterm) + 1;
         *tracer = copy_struct(tracer_state, sz, &hp, &hf->off_heap);
         *tracer = CONS(hf->mem, tracer_module, *tracer);
         ASSERT((void*)(((char*)(ptr_val(*tracer)) - offsetof(ErlHeapFragment, mem))) == hf);