com32/lib/syslinux/zonelist.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 /*
  29  * zonelist.c
  30  *
  31  * Deal with syslinux_memmap's, which are data structures designed to
  32  * hold memory maps.  A zonelist is a sorted linked list of memory
  33  * ranges, with the guarantee that no two adjacent blocks have the
  34  * same range type.  Additionally, all unspecified memory have a range
  35  * type of zero.
  36  */
  37
  38 #include <stdlib.h>
  39 #include <syslinux/movebits.h>
  40
  41 /*
  42  * Create an empty syslinux_memmap list.
  43  */
  44 struct syslinux_memmap *syslinux_init_memmap(void)
  45 {
  46   struct syslinux_memmap *sp, *ep;
  47
  48   sp = malloc(sizeof(*sp));
  49   if (!sp)
  50     return NULL;
  51
  52   ep = malloc(sizeof(*ep));
  53   if (!ep) {
  54     free(sp);
  55     return NULL;
  56   }
  57
  58   sp->start = 0;
  59   sp->type  = SMT_UNDEFINED;
  60   sp->next  = ep;
  61
  62   ep->start = 0;                /* Wrap around... */
  63   ep->type  = SMT_END;          /* End of chain */
  64   ep->next  = NULL;
  65
  66   return sp;
  67 }
  68
  69 /*
  70  * Add an item to a syslinux_memmap list, potentially overwriting
  71  * what is already there.
  72  */
  73 int syslinux_add_memmap(struct syslinux_memmap **list,
  74                         addr_t start, addr_t len,
  75                         enum syslinux_memmap_types type)
  76 {
  77   addr_t last;
  78   struct syslinux_memmap *mp, **mpp;
  79   struct syslinux_memmap *mpi;
  80   struct syslinux_memmap *range;
  81   enum syslinux_memmap_types oldtype;
  82
  83   /* Remove this to make len == 0 mean all of memory */
  84   if (len == 0)
  85     return 0;
  86
  87   /* Last byte -- to avoid rollover */
  88   last = start+len-1;
  89
  90   mpp = list;
  91   oldtype = SMT_ERROR;
  92   while (mp = *mpp, start > mp->start && mp->type != SMT_END) {
  93     oldtype = mp->type;
  94     mpp = &mp->next;
  95   }
  96
  97   if (start < mp->start || mp->type == SMT_END) {
  98     range = malloc(sizeof(*range));
  99     if (!range)
 100       return -1;
 101
 102     range->start = start;
 103     range->type  = type;
 104     *mpp = range;
 105     range->next = mp;
 106     mpp = &range->next;
 107   }
 108
 109   while (mp = *mpp, last > mp->start-1) {
 110     oldtype = mp->type;
 111     mp->type = type;
 112     mpp = &mp->next;
 113   }
 114
 115   if (last < mp->start-1) {
 116     range = malloc(sizeof(*range));
 117     if (!range)
 118       return -1;
 119
 120     range->start = last+1;
 121     range->type  = oldtype;
 122     *mpp = range;
 123     range->next = mp;
 124   }
 125
 126   /* Now the map is correct, but quite possibly not optimal.  Scan the
 127      map for ranges which are redundant and remove them.  This is
 128      technically excessive, since we scan the list to the end even
 129      though only part of it could have changed.  In particular, the first
 130      entry that could change is one earlier than the first one changed
 131      above, and once we stop changing things, there shouldn't be any
 132      more changes. */
 133   mpi = *list;
 134   while (mpi->type != SMT_END) {
 135     mp = mpi->next;
 136     if (mpi->type == mp->type) {
 137       mpi->next = mp->next;
 138       free(mp);
 139     } else {
 140       /* Go on to the next one */
 141       mpi = mp;
 142     }
 143   }
 144
 145   return 0;
 146 }
 147
 148 /*
 149  * Verify what type a certain memory region is.  This function returns
 150  * SMT_ERROR if the memory region has multiple types.
 151  */
 152 enum syslinux_memmap_types syslinux_memmap_type(struct syslinux_memmap *list,
 153                                                 addr_t start, addr_t len)
 154 {
 155   addr_t last, llast;
 156
 157   last = start+len-1;
 158
 159   while (list->type != SMT_END) {
 160     llast = list->next->start-1;
 161     if (list->start <= start) {
 162       if (llast >= last)
 163         return list->type;      /* Region has a well-defined type */
 164       else if (llast >= start)
 165         return SMT_ERROR;       /* Crosses region boundary */
 166     }
 167     list = list->next;
 168   }
 169
 170   return SMT_ERROR;             /* Internal error? */
 171 }
 172
 173 /*
 174  * Find the largest zone of a specific type.  Returns -1 on failure.
 175  */
 176 int syslinux_memmap_largest(struct syslinux_memmap *list,
 177                             enum syslinux_memmap_types type,
 178                             addr_t *start, addr_t *len)
 179 {
 180   addr_t size, best_size = 0;
 181   struct syslinux_memmap *best = NULL;
 182
 183   while (list->type != SMT_END) {
 184     size = list->next->start - list->start;
 185
 186     if (list->type == type && size > best_size) {
 187       best = list;
 188       best_size = size;
 189     }
 190
 191     list = list->next;
 192   }
 193
 194   if (!best)
 195     return -1;
 196
 197   *start = best->start;
 198   *len = best_size;
 199
 200   return 0;
 201 }
 202
 203 /*
 204  * Free a zonelist.
 205  */
 206 void syslinux_free_memmap(struct syslinux_memmap *list)
 207 {
 208   struct syslinux_memmap *ml;
 209
 210   while (list) {
 211     ml = list;
 212     list = list->next;
 213     free(ml);
 214   }
 215 }
 216
 217 /*
 218  * Duplicate a zonelist.  Returns NULL on failure.
 219  */
 220 struct syslinux_memmap *syslinux_dup_memmap(struct syslinux_memmap *list)
 221 {
 222   struct syslinux_memmap *newlist = NULL, **nlp = &newlist;
 223   struct syslinux_memmap *ml;
 224
 225   while (list) {
 226     ml = malloc(sizeof(*ml));
 227     if (!ml) {
 228       syslinux_free_memmap(newlist);
 229       return NULL;
 230     }
 231     ml->start = list->start;
 232     ml->type = list->type;
 233     ml->next = NULL;
 234     *nlp = ml;
 235     nlp = &ml->next;
 236
 237     list = list->next;
 238   }
 239
 240   return newlist;
 241 }