src/libs/libunwind/mi/mempool.c

   1 /* libunwind - a platform-independent unwind library
   2    Copyright (C) 2002-2003, 2005 Hewlett-Packard Co
   3         Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
   4    Copyright (C) 2012 Tommi Rantala <tt.rantala@gmail.com>
   5
   6 This file is part of libunwind.
   7
   8 Permission is hereby granted, free of charge, to any person obtaining
   9 a copy of this software and associated documentation files (the
  10 "Software"), to deal in the Software without restriction, including
  11 without limitation the rights to use, copy, modify, merge, publish,
  12 distribute, sublicense, and/or sell copies of the Software, and to
  13 permit persons to whom the Software is furnished to do so, subject to
  14 the following conditions:
  15
  16 The above copyright notice and this permission notice shall be
  17 included in all copies or substantial portions of the Software.
  18
  19 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  20 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  21 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  22 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  23 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  24 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  25 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
  26
  27 #include "libunwind_i.h"
  28
  29 /* From GCC docs: ``Gcc also provides a target specific macro
  30  * __BIGGEST_ALIGNMENT__, which is the largest alignment ever used for any data
  31  * type on the target machine you are compiling for.'' */
  32 #ifdef __BIGGEST_ALIGNMENT__
  33 # define MAX_ALIGN      __BIGGEST_ALIGNMENT__
  34 #else
  35 /* Crude hack to check that MAX_ALIGN is power-of-two.
  36  * sizeof(long double) = 12 on i386. */
  37 # define MAX_ALIGN_(n)  (n < 8 ? 8 : \
  38                          n < 16 ? 16 : n)
  39 # define MAX_ALIGN      MAX_ALIGN_(sizeof (long double))
  40 #endif
  41
  42 static char sos_memory[SOS_MEMORY_SIZE] ALIGNED(MAX_ALIGN);
  43 static size_t sos_memory_freepos;
  44 static size_t pg_size;
  45
  46 HIDDEN void *
  47 sos_alloc (size_t size)
  48 {
  49   size_t pos;
  50
  51   size = UNW_ALIGN(size, MAX_ALIGN);
  52
  53 #if defined(__GNUC__) && defined(HAVE_FETCH_AND_ADD)
  54   /* Assume `sos_memory' is suitably aligned. */
  55   assert(((uintptr_t) &sos_memory[0] & (MAX_ALIGN-1)) == 0);
  56
  57   pos = fetch_and_add (&sos_memory_freepos, size);
  58 #else
  59   static define_lock (sos_lock);
  60   intrmask_t saved_mask;
  61
  62   lock_acquire (&sos_lock, saved_mask);
  63   {
  64     /* No assumptions about `sos_memory' alignment. */
  65     if (sos_memory_freepos == 0)
  66       {
  67         unsigned align = UNW_ALIGN((uintptr_t) &sos_memory[0], MAX_ALIGN)
  68                                 - (uintptr_t) &sos_memory[0];
  69         sos_memory_freepos = align;
  70       }
  71     pos = sos_memory_freepos;
  72     sos_memory_freepos += size;
  73   }
  74   lock_release (&sos_lock, saved_mask);
  75 #endif
  76
  77   assert (((uintptr_t) &sos_memory[pos] & (MAX_ALIGN-1)) == 0);
  78   assert ((pos+size) <= SOS_MEMORY_SIZE);
  79
  80   return &sos_memory[pos];
  81 }
  82
  83 /* Must be called while holding the mempool lock. */
  84
  85 static void
  86 free_object (struct mempool *pool, void *object)
  87 {
  88   struct object *obj = object;
  89
  90   obj->next = pool->free_list;
  91   pool->free_list = obj;
  92   ++pool->num_free;
  93 }
  94
  95 static void
  96 add_memory (struct mempool *pool, char *mem, size_t size, size_t obj_size)
  97 {
  98   char *obj;
  99
 100   for (obj = mem; obj <= mem + size - obj_size; obj += obj_size)
 101     free_object (pool, obj);
 102 }
 103
 104 static void
 105 expand (struct mempool *pool)
 106 {
 107   size_t size;
 108   char *mem;
 109
 110   size = pool->chunk_size;
 111   GET_MEMORY (mem, size);
 112   if (!mem)
 113     {
 114       size = UNW_ALIGN(pool->obj_size, pg_size);
 115       GET_MEMORY (mem, size);
 116       if (!mem)
 117         {
 118           /* last chance: try to allocate one object from the SOS memory */
 119           size = pool->obj_size;
 120           mem = sos_alloc (size);
 121         }
 122     }
 123   add_memory (pool, mem, size, pool->obj_size);
 124 }
 125
 126 HIDDEN void
 127 mempool_init (struct mempool *pool, size_t obj_size, size_t reserve)
 128 {
 129   if (pg_size == 0)
 130     pg_size = getpagesize ();
 131
 132   memset (pool, 0, sizeof (*pool));
 133
 134   lock_init (&pool->lock);
 135
 136   /* round object-size up to integer multiple of MAX_ALIGN */
 137   obj_size = UNW_ALIGN(obj_size, MAX_ALIGN);
 138
 139   if (!reserve)
 140     {
 141       reserve = pg_size / obj_size / 4;
 142       if (!reserve)
 143         reserve = 16;
 144     }
 145
 146   pool->obj_size = obj_size;
 147   pool->reserve = reserve;
 148   pool->chunk_size = UNW_ALIGN(2*reserve*obj_size, pg_size);
 149
 150   expand (pool);
 151 }
 152
 153 HIDDEN void *
 154 mempool_alloc (struct mempool *pool)
 155 {
 156   intrmask_t saved_mask;
 157   struct object *obj;
 158
 159   lock_acquire (&pool->lock, saved_mask);
 160   {
 161     if (pool->num_free <= pool->reserve)
 162       expand (pool);
 163
 164     assert (pool->num_free > 0);
 165
 166     --pool->num_free;
 167     obj = pool->free_list;
 168     pool->free_list = obj->next;
 169   }
 170   lock_release (&pool->lock, saved_mask);
 171   return obj;
 172 }
 173
 174 HIDDEN void
 175 mempool_free (struct mempool *pool, void *object)
 176 {
 177   intrmask_t saved_mask;
 178
 179   lock_acquire (&pool->lock, saved_mask);
 180   {
 181     free_object (pool, object);
 182   }
 183   lock_release (&pool->lock, saved_mask);
 184 }