Remove OpenBSD uthreads (GC_OPENBSD_UTHREADS) support

Issue #512 (bdwgc).

Userland threads were replaced by rthreads on OpenBSD about a decade
ago.  Prior to OpenBSD 5.2 release (2012), the OS had user threads
and required special handling.

* include/private/gc_priv.h [GC_OPENBSD_THREADS
&& !GC_USESIGRT_SIGNALS] (SIG_SUSPEND): Do not check
GC_OPENBSD_UTHREADS (assume not defined).
* include/private/gcconfig.h [OPENBSD] (NEED_FIND_LIMIT): Likewise.
* include/private/gcconfig.h [PTHREAD_STOP_WORLD_IMPL && !NACL]
(SIGNAL_BASED_STOP_WORLD): Likewise.
* os_dep.c [OPENBSD] (GC_register_data_segments): Likewise.
* pthread_stop_world.c (GC_usleep, GC_suspend_all, GC_stop_world,
GC_start_world, GC_stop_init): Likewise.
* tests/initfromthread.c (main): Likewise.
* include/private/gcconfig.h [GC_OPENBSD_THREADS && OpenBSD<201211]
(GC_OPENBSD_UTHREADS): Do not define.
* os_dep.c [OPENBSD && GC_OPENBSD_UTHREADS]: Do not include
sys/syscall.h.
* os_dep.c [OPENBSD && GC_OPENBSD_UTHREADS] (__syscall): Do not
declare.
* os_dep.c [OPENBSD && GC_OPENBSD_UTHREADS] (GC_find_limit_openbsd):
Remove.
* os_dep.c [NEED_FIND_LIMIT || USE_PROC_FOR_LIBRARIES && THREADS]
(GC_find_limit_with_bound): Move comment from GC_find_limit_openbsd.
* pthread_stop_world.c [!NACL && GC_OPENBSD_UTHREADS]: Do not include
pthread_np.h.

Co-authored-by: Kurt Miller <bsdkurt@gmail.com>

1 files changed, 5 insertions, 60 deletions

diff --git a/os_dep.c b/os_dep.c
index 8e140836..42b0fa06 100644
--- a/os_dep.c
+++ b/os_dep.c
@@ -524,60 +524,6 @@ GC_INNER const char * GC_get_maps(void)
      LONGJMP(GC_jmp_buf_openbsd, 1);
   }
 
-# ifdef GC_OPENBSD_UTHREADS
-#   include <sys/syscall.h>
-    EXTERN_C_BEGIN
-    extern sigset_t __syscall(quad_t, ...);
-    EXTERN_C_END
-
-  /* Don't use GC_find_limit() because siglongjmp() outside of the      */
-  /* signal handler by-passes our userland pthreads lib, leaving        */
-  /* SIGSEGV and SIGPROF masked.  Instead, use this custom one that     */
-  /* works-around the issues.                                           */
-
-  /* Return the first non-addressable location > p or bound.    */
-  STATIC ptr_t GC_find_limit_openbsd(ptr_t p, ptr_t bound)
-  {
-    static volatile ptr_t result;
-             /* Safer if static, since otherwise it may not be  */
-             /* preserved across the longjmp.  Can safely be    */
-             /* static since it's only called with the          */
-             /* allocation lock held.                           */
-
-    struct sigaction act;
-    word pgsz = (word)sysconf(_SC_PAGESIZE);
-
-    GC_ASSERT((word)bound >= pgsz);
-    GC_ASSERT(I_HOLD_LOCK());
-
-    act.sa_handler = GC_fault_handler_openbsd;
-    sigemptyset(&act.sa_mask);
-    act.sa_flags = SA_NODEFER | SA_RESTART;
-    /* act.sa_restorer is deprecated and should not be initialized. */
-    sigaction(SIGSEGV, &act, &old_segv_act);
-
-    if (SETJMP(GC_jmp_buf_openbsd) == 0) {
-      result = (ptr_t)((word)p & ~(pgsz-1));
-      for (;;) {
-        if ((word)result >= (word)bound - pgsz) {
-          result = bound;
-          break;
-        }
-        result += pgsz; /* no overflow expected */
-        GC_noop1((word)(*result));
-      }
-    }
-
-#   ifdef THREADS
-      /* Due to the siglongjump we need to manually unmask SIGPROF.     */
-      __syscall(SYS_sigprocmask, SIG_UNBLOCK, sigmask(SIGPROF));
-#   endif
-
-    sigaction(SIGSEGV, &old_segv_act, 0);
-    return result;
-  }
-# endif /* GC_OPENBSD_UTHREADS */
-
   static volatile int firstpass;
 
   /* Return first addressable location > p or bound.    */
@@ -995,7 +941,10 @@ GC_INNER size_t GC_page_size = 0;
     STATIC ptr_t GC_find_limit_with_bound(ptr_t p, GC_bool up, ptr_t bound)
     {
         static volatile ptr_t result;
-                /* Safer if static, see that in GC_find_limit_openbsd.  */
+                /* Safer if static, since otherwise it may not be   */
+                /* preserved across the longjmp.  Can safely be     */
+                /* static since it's only called with the           */
+                /* allocation lock held.                            */
 
         GC_ASSERT(up ? (word)bound >= MIN_PAGE_SIZE
                      : (word)bound <= ~(word)MIN_PAGE_SIZE);
@@ -2091,11 +2040,7 @@ void GC_register_data_segments(void)
     ABORT_ARG2("Wrong DATASTART/END pair",
                ": %p .. %p", (void *)region_start, (void *)DATAEND);
   for (;;) {
-#   ifdef GC_OPENBSD_UTHREADS
-      ptr_t region_end = GC_find_limit_openbsd(region_start, DATAEND);
-#   else
-      ptr_t region_end = GC_find_limit_with_bound(region_start, TRUE, DATAEND);
-#   endif
+    ptr_t region_end = GC_find_limit_with_bound(region_start, TRUE, DATAEND);
 
     GC_add_roots_inner(region_start, region_end, FALSE);
     if ((word)region_end >= (word)DATAEND)