libitm/clone.cc

   1 /* Copyright (C) 2009-2021 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson <rth@redhat.com>.
   3
   4    This file is part of the GNU Transactional Memory Library (libitm).
   5
   6    Libitm is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
  12    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14    more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 #include "libitm_i.h"
  26
  27 using namespace GTM;
  28
  29 struct clone_entry
  30 {
  31   void *orig, *clone;
  32 };
  33
  34 struct clone_table
  35 {
  36   clone_entry *table;
  37   size_t size;
  38   clone_table *next;
  39 };
  40
  41 static clone_table *all_tables;
  42
  43 static void *
  44 find_clone (void *ptr)
  45 {
  46   clone_table *table;
  47
  48   for (table = all_tables; table ; table = table->next)
  49     {
  50       clone_entry *t = table->table;
  51       size_t lo = 0, hi = table->size, i;
  52
  53       /* Quick test for whether PTR is present in this table.  */
  54       if (ptr < t[0].orig || ptr > t[hi - 1].orig)
  55         continue;
  56
  57       /* Otherwise binary search.  */
  58       while (lo < hi)
  59         {
  60           i = (lo + hi) / 2;
  61           if (ptr < t[i].orig)
  62             hi = i;
  63           else if (ptr > t[i].orig)
  64             lo = i + 1;
  65           else
  66             return t[i].clone;
  67         }
  68
  69       /* Given the quick test above, if we don't find the entry in
  70          this table then it doesn't exist.  */
  71       break;
  72     }
  73
  74   return NULL;
  75 }
  76
  77
  78 void * ITM_REGPARM
  79 _ITM_getTMCloneOrIrrevocable (void *ptr)
  80 {
  81   void *ret = find_clone (ptr);
  82   if (ret)
  83     return ret;
  84
  85   gtm_thr()->serialirr_mode ();
  86
  87   return ptr;
  88 }
  89
  90 void * ITM_REGPARM
  91 _ITM_getTMCloneSafe (void *ptr)
  92 {
  93   void *ret = find_clone (ptr);
  94   if (ret == NULL)
  95     abort ();
  96   return ret;
  97 }
  98
  99 static int
 100 clone_entry_compare (const void *a, const void *b)
 101 {
 102   const clone_entry *aa = (const clone_entry *)a;
 103   const clone_entry *bb = (const clone_entry *)b;
 104
 105   if (aa->orig < bb->orig)
 106     return -1;
 107   else if (aa->orig > bb->orig)
 108     return 1;
 109   else
 110     return 0;
 111 }
 112
 113 namespace {
 114
 115 // Within find_clone, we know that we are inside a transaction.  Because
 116 // of that, we have already synchronized with serial_lock.  By taking the
 117 // serial_lock for write, we exclude all transactions while we make this
 118 // change to the clone tables, without having to synchronize on a separate
 119 // lock.  Do be careful not to attempt a recursive write lock.
 120
 121 class ExcludeTransaction
 122 {
 123   bool do_lock;
 124
 125  public:
 126   ExcludeTransaction()
 127   {
 128     gtm_thread *tx = gtm_thr();
 129     do_lock = !(tx && (tx->state & gtm_thread::STATE_SERIAL));
 130
 131     if (do_lock)
 132       gtm_thread::serial_lock.write_lock ();
 133   }
 134
 135   ~ExcludeTransaction()
 136   {
 137     if (do_lock)
 138       gtm_thread::serial_lock.write_unlock ();
 139   }
 140 };
 141
 142 } // end anon namespace
 143
 144
 145 void
 146 _ITM_registerTMCloneTable (void *xent, size_t size)
 147 {
 148   clone_entry *ent = static_cast<clone_entry *>(xent);
 149   clone_table *table;
 150
 151   table = (clone_table *) xmalloc (sizeof (clone_table));
 152   table->table = ent;
 153   table->size = size;
 154
 155   qsort (ent, size, sizeof (clone_entry), clone_entry_compare);
 156
 157   // Hold the serial_lock while we update the ALL_TABLES datastructure.
 158   {
 159     ExcludeTransaction exclude;
 160     table->next = all_tables;
 161     all_tables = table;
 162   }
 163 }
 164
 165 void
 166 _ITM_deregisterTMCloneTable (void *xent)
 167 {
 168   clone_entry *ent = static_cast<clone_entry *>(xent);
 169   clone_table *tab;
 170
 171   // Hold the serial_lock while we update the ALL_TABLES datastructure.
 172   {
 173     ExcludeTransaction exclude;
 174     clone_table **pprev;
 175
 176     for (pprev = &all_tables;
 177          tab = *pprev, tab->table != ent;
 178          pprev = &tab->next)
 179       continue;
 180     *pprev = tab->next;
 181   }
 182
 183   free (tab);
 184 }