libgcc/generic-morestack-thread.c

   1 /* Thread library support for -fsplit-stack.  */
   2 /* Copyright (C) 2009, 2010 Free Software Foundation, Inc.
   3    Contributed by Ian Lance Taylor <iant@google.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #include "tconfig.h"
  27 #include "tsystem.h"
  28 #include "coretypes.h"
  29 #include "tm.h"
  30
  31 /* If inhibit_libc is defined, we can not compile this file.  The
  32    effect is that people will not be able to use -fsplit-stack.  That
  33    is much better than failing the build particularly since people
  34    will want to define inhibit_libc while building a compiler which
  35    can build glibc.  */
  36
  37 #ifndef inhibit_libc
  38
  39 #include <pthread.h>
  40
  41 #include "generic-morestack.h"
  42
  43 /* We declare the pthread functions we need as weak, so that
  44    libgcc_s.so does not need to be linked against -lpthread.  */
  45
  46 extern int pthread_once (pthread_once_t *, void (*) (void))
  47   __attribute__ ((weak));
  48
  49 extern int pthread_key_create (pthread_key_t *, void (*) (void *))
  50   __attribute__ ((weak));
  51
  52 extern int pthread_setspecific (pthread_key_t, const void *)
  53   __attribute__ ((weak));
  54
  55 /* The key for the list of stack segments to free when the thread
  56    exits.  This is created by pthread_key_create.  */
  57
  58 static pthread_key_t segment_list_key;
  59
  60 /* Used to only run create_key once.  */
  61
  62 static pthread_once_t create_key_once = PTHREAD_ONCE_INIT;
  63
  64 /* Release all the segments for a thread.  This is the destructor
  65    function used by pthread_key_create, and is called when a thread
  66    exits.  */
  67
  68 static void
  69 free_segments (void* arg)
  70 {
  71   __morestack_release_segments ((struct stack_segment **) arg, 1);
  72 }
  73
  74 /* Set up the key for the list of segments.  This is called via
  75    pthread_once.  */
  76
  77 static void
  78 create_key (void)
  79 {
  80   int err;
  81
  82   err = pthread_key_create (&segment_list_key, free_segments);
  83   if (err != 0)
  84     {
  85       static const char msg[] = "pthread_key_create failed: errno ";
  86       __morestack_fail (msg, sizeof msg - 1, err);
  87     }
  88 }
  89
  90 /* Pass information from the pthread_create wrapper to
  91    stack_split_initialize_thread.  */
  92
  93 struct pthread_create_args
  94 {
  95   void *(*start_routine) (void *);
  96   void *arg;
  97 };
  98
  99 /* Initialize a thread.  This is called via pthread_create.  It calls
 100    a target dependent function to set up any required stack guard.  */
 101
 102 static void* stack_split_initialize_thread (void *)
 103   __attribute__ ((no_split_stack));
 104
 105 static void *
 106 stack_split_initialize_thread (void *varg)
 107 {
 108   struct pthread_create_args *args = (struct pthread_create_args *) varg;
 109   int err;
 110   void *(*start_routine) (void *);
 111   void *arg;
 112
 113   __stack_split_initialize ();
 114
 115   err = pthread_setspecific (segment_list_key, (void *) &__morestack_segments);
 116   if (err != 0)
 117     {
 118       static const char msg[] = "pthread_setspecific failed: errno ";
 119       __morestack_fail (msg, sizeof msg - 1, err);
 120     }
 121
 122   start_routine = args->start_routine;
 123   arg = args->arg;
 124   free (args);
 125   return (*start_routine) (arg);
 126 }
 127
 128 /* This function wraps calls to pthread_create to make sure that the
 129    stack guard is initialized for new threads.  FIXME: This hack will
 130    not be necessary if glibc supports -fsplit-stack directly.  */
 131
 132 int __wrap_pthread_create (pthread_t *, const pthread_attr_t *,
 133                            void *(*start_routine) (void *), void *)
 134   __attribute__ ((visibility ("hidden")));
 135
 136 extern int __real_pthread_create (pthread_t *, const pthread_attr_t *,
 137                                   void *(*start_routine) (void *), void *)
 138   __attribute__ ((weak));
 139
 140 int
 141 __wrap_pthread_create (pthread_t *tid, const pthread_attr_t *attr,
 142                        void *(*start_routine) (void *), void *arg)
 143 {
 144   int err;
 145   struct pthread_create_args* args;
 146
 147   err = pthread_once (&create_key_once, create_key);
 148   if (err != 0)
 149     {
 150       static const char msg[] = "pthread_once failed: errno ";
 151       __morestack_fail (msg, sizeof msg - 1, err);
 152     }
 153
 154   args = malloc (sizeof (struct pthread_create_args));
 155   if (args == NULL)
 156     return EAGAIN;
 157   args->start_routine = start_routine;
 158   args->arg = arg;
 159   return __real_pthread_create (tid, attr, stack_split_initialize_thread, args);
 160 }
 161
 162 #endif /* !defined (inhibit_libc) */