libgo/runtime/thread.c

   1 // Copyright 2010 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 #include <errno.h>
   6 #include <signal.h>
   7
   8 #include "runtime.h"
   9 #include "go-assert.h"
  10
  11 /* For targets which don't have the required sync support.  Really
  12    these should be provided by gcc itself.  FIXME.  */
  13
  14 #if !defined (HAVE_SYNC_BOOL_COMPARE_AND_SWAP_4) || !defined (HAVE_SYNC_FETCH_AND_ADD_4)
  15
  16 static pthread_mutex_t sync_lock = PTHREAD_MUTEX_INITIALIZER;
  17
  18 #endif
  19
  20 #ifndef HAVE_SYNC_BOOL_COMPARE_AND_SWAP_4
  21
  22 _Bool
  23 __sync_bool_compare_and_swap_4 (uint32*, uint32, uint32)
  24   __attribute__ ((visibility ("hidden")));
  25
  26 _Bool
  27 __sync_bool_compare_and_swap_4 (uint32* ptr, uint32 old, uint32 new)
  28 {
  29   int i;
  30   _Bool ret;
  31
  32   i = pthread_mutex_lock (&sync_lock);
  33   __go_assert (i == 0);
  34
  35   if (*ptr != old)
  36     ret = 0;
  37   else
  38     {
  39       *ptr = new;
  40       ret = 1;
  41     }
  42
  43   i = pthread_mutex_unlock (&sync_lock);
  44   __go_assert (i == 0);
  45
  46   return ret;
  47 }
  48
  49 #endif
  50
  51 #ifndef HAVE_SYNC_FETCH_AND_ADD_4
  52
  53 uint32
  54 __sync_fetch_and_add_4 (uint32*, uint32)
  55   __attribute__ ((visibility ("hidden")));
  56
  57 uint32
  58 __sync_fetch_and_add_4 (uint32* ptr, uint32 add)
  59 {
  60   int i;
  61   uint32 ret;
  62
  63   i = pthread_mutex_lock (&sync_lock);
  64   __go_assert (i == 0);
  65
  66   ret = *ptr;
  67   *ptr += add;
  68
  69   i = pthread_mutex_unlock (&sync_lock);
  70   __go_assert (i == 0);
  71
  72   return ret;
  73 }
  74
  75 #endif
  76
  77 // Called to initialize a new m (including the bootstrap m).
  78 void
  79 runtime_minit(void)
  80 {
  81         byte* stack;
  82         size_t stacksize;
  83         stack_t ss;
  84
  85         // Initialize signal handling.
  86         runtime_m()->gsignal = runtime_malg(32*1024, &stack, &stacksize);       // OS X wants >=8K, Linux >=2K
  87         ss.ss_sp = stack;
  88         ss.ss_flags = 0;
  89         ss.ss_size = stacksize;
  90         if(sigaltstack(&ss, nil) < 0)
  91                 *(int *)0xf1 = 0xf1;
  92 }