runtime/gc/signals.c

   1 /* Copyright (C) 2010,2016 Matthew Fluet.
   2  * Copyright (C) 1999-2006 Henry Cejtin, Matthew Fluet, Suresh
   3  *    Jagannathan, and Stephen Weeks.
   4  * Copyright (C) 1997-2000 NEC Research Institute.
   5  *
   6  * MLton is released under a BSD-style license.
   7  * See the file MLton-LICENSE for details.
   8  */
   9
  10 #if not HAS_SIGALTSTACK
  11
  12 void initSignalStack (__attribute__ ((unused)) GC_state s) {
  13 }
  14
  15 #else
  16
  17 void initSignalStack (GC_state s) {
  18   static bool init = FALSE;
  19   static stack_t altstack;
  20
  21   if (! init) {
  22     init = TRUE;
  23     size_t ss_size = align (SIGSTKSZ, s->sysvals.pageSize);
  24     size_t psize = s->sysvals.pageSize;
  25     int prot = PROT_READ | PROT_WRITE;
  26 #if NEEDS_SIGALTSTACK_EXEC
  27     prot = prot | PROT_EXEC;
  28 #endif
  29     void *ss_sp = GC_mmapAnon_safe_protect (NULL, 2 * ss_size, prot, psize, psize);
  30     altstack.ss_sp = (void*)((pointer)ss_sp + ss_size);
  31     altstack.ss_size = ss_size;
  32     altstack.ss_flags = 0;
  33   }
  34   sigaltstack (&altstack, NULL);
  35 }
  36
  37 #endif
  38
  39 void GC_initSignalStack (GC_state s) {
  40   initSignalStack (s);
  41 }