Kernel/heap.c

   1 /*
   2  * AcessOS Microkernel Version
   3  * heap.c
   4  */
   5 #include <common.h>
   6 #include <mm_virt.h>
   7 #include <heap.h>
   8
   9 #define WARNINGS        1
  10 #define DEBUG_TRACE     0
  11
  12 // === CONSTANTS ===
  13 #define HEAP_BASE       0xE0800000
  14 #define HEAP_MAX        0xF0000000      // 120MiB, Plenty
  15 #define HEAP_INIT_SIZE  0x8000  // 32 KiB
  16 #define BLOCK_SIZE      (sizeof(void*)) // 8 Machine Words
  17 #define COMPACT_HEAP    0       // Use 4 byte header?
  18 #define FIRST_FIT       0
  19
  20 #define MAGIC_FOOT      0x2ACE5505
  21 #define MAGIC_FREE      0xACE55000
  22 #define MAGIC_USED      0x862B0505      // MAGIC_FOOT ^ MAGIC_FREE
  23
  24 // === PROTOTYPES ===
  25 void    Heap_Install();
  26 void    *Heap_Extend(int Bytes);
  27 void    *Heap_Merge(tHeapHead *Head);
  28 void    *malloc(size_t Bytes);
  29 void    free(void *Ptr);
  30 void    Heap_Dump();
  31
  32 // === GLOBALS ===
  33  int    giHeapSpinlock;
  34 void    *gHeapStart;
  35 void    *gHeapEnd;
  36
  37 // === CODE ===
  38 void Heap_Install()
  39 {
  40         gHeapStart      = (void*)MM_KHEAP_BASE;
  41         gHeapEnd        = (void*)MM_KHEAP_BASE;
  42         Heap_Extend(HEAP_INIT_SIZE);
  43 }
  44
  45 /**
  46  * \fn void *Heap_Extend(int Bytes)
  47  * \brief Extend the size of the heap
  48  */
  49 void *Heap_Extend(int Bytes)
  50 {
  51         Uint    i;
  52         tHeapHead       *head = gHeapEnd;
  53         tHeapFoot       *foot;
  54
  55         // Bounds Check
  56         if( (Uint)gHeapEnd == MM_KHEAP_MAX )
  57                 return NULL;
  58
  59         // Bounds Check
  60         if( (Uint)gHeapEnd + ((Bytes+0xFFF)&~0xFFF) > MM_KHEAP_MAX ) {
  61                 Bytes = MM_KHEAP_MAX - (Uint)gHeapEnd;
  62                 return NULL;
  63         }
  64
  65         // Heap expands in pages
  66         for(i=0;i<(Bytes+0xFFF)>>12;i++)
  67                 MM_Allocate( (Uint)gHeapEnd+(i<<12) );
  68
  69         // Increas heap end
  70         gHeapEnd += i << 12;
  71
  72         // Create Block
  73         head->Size = (Bytes+0xFFF)&~0xFFF;
  74         head->Magic = MAGIC_FREE;
  75         foot = (void*)( (Uint)gHeapEnd - sizeof(tHeapFoot) );
  76         foot->Head = head;
  77         foot->Magic = MAGIC_FOOT;
  78
  79         //Log(" Heap_Extend: head = %p", head);
  80         return Heap_Merge(head);        // Merge with previous block
  81 }
  82
  83 /**
  84  * \fn void *Heap_Merge(tHeapHead *Head)
  85  * \brief Merges two ajacent heap blocks
  86  */
  87 void *Heap_Merge(tHeapHead *Head)
  88 {
  89         tHeapFoot       *foot;
  90         tHeapFoot       *thisFoot;
  91         tHeapHead       *head;
  92
  93         //Log("Heap_Merge: (Head=%p)", Head);
  94
  95         thisFoot = (void*)( (Uint)Head + Head->Size - sizeof(tHeapFoot) );
  96         if((Uint)thisFoot > (Uint)gHeapEnd)     return NULL;
  97
  98         // Merge Left (Down)
  99         foot = (void*)( (Uint)Head - sizeof(tHeapFoot) );
 100         if( ((Uint)foot < (Uint)gHeapEnd && (Uint)foot > HEAP_BASE)
 101         && foot->Head->Magic == MAGIC_FREE) {
 102                 foot->Head->Size += Head->Size; // Increase size
 103                 thisFoot->Head = foot->Head;    // Change backlink
 104                 Head->Magic = 0;        // Clear old head
 105                 Head->Size = 0;
 106                 Head = foot->Head;      // Save new head address
 107                 foot->Head = NULL;      // Clear central footer
 108                 foot->Magic = 0;
 109         }
 110
 111         // Merge Right (Upwards)
 112         head = (void*)( (Uint)Head + Head->Size );
 113         if((Uint)head < (Uint)gHeapEnd && head->Magic == MAGIC_FREE)
 114         {
 115                 Head->Size += head->Size;
 116                 foot = (void*)( (Uint)Head + Head->Size - sizeof(tHeapFoot) );
 117                 foot->Head = Head;      // Update Backlink
 118                 thisFoot->Head = NULL;  // Clear old footer
 119                 thisFoot->Magic = 0;
 120                 head->Size = 0;         // Clear old header
 121                 head->Magic = 0;
 122         }
 123
 124         // Return new address
 125         return Head;
 126 }
 127
 128 /**
 129  * \fn void *malloc(size_t Bytes)
 130  * \brief Allocate memory from the heap
 131  */
 132 void *malloc(size_t Bytes)
 133 {
 134         tHeapHead       *head, *newhead;
 135         tHeapFoot       *foot, *newfoot;
 136         tHeapHead       *best = NULL;
 137         Uint    bestSize = 0;   // Speed hack
 138
 139         // Get required size
 140         Bytes = (Bytes + sizeof(tHeapHead) + sizeof(tHeapFoot) + BLOCK_SIZE-1) & ~(BLOCK_SIZE-1);
 141
 142         // Lock Heap
 143         LOCK(&giHeapSpinlock);
 144
 145         // Traverse Heap
 146         for( head = gHeapStart;
 147                 (Uint)head < (Uint)gHeapEnd;
 148                 head = (void*)((Uint)head + head->Size)
 149                 )
 150         {
 151                 // Alignment Check
 152                 if( head->Size & (BLOCK_SIZE-1) ) {
 153                         #if WARNINGS
 154                         Warning("Size of heap address %p is invalid not aligned (0x%x)", head, head->Size);
 155                         Heap_Dump();
 156                         #endif
 157                         return NULL;
 158                 }
 159
 160                 // Check if allocated
 161                 if(head->Magic == MAGIC_USED)   continue;
 162                 // Error check
 163                 if(head->Magic != MAGIC_FREE)   {
 164                         #if WARNINGS
 165                         Warning("Magic of heap address %p is invalid (0x%x)", head, head->Magic);
 166                         Heap_Dump();
 167                         #endif
 168                         RELEASE(&giHeapSpinlock);       // Release spinlock
 169                         return NULL;
 170                 }
 171
 172                 // Size check
 173                 if(head->Size < Bytes)  continue;
 174
 175                 // Perfect fit
 176                 if(head->Size == Bytes) {
 177                         head->Magic = MAGIC_USED;
 178                         RELEASE(&giHeapSpinlock);       // Release spinlock
 179                         #if DEBUG_TRACE
 180                         LOG("RETURN %p, to %p", best->Data, __builtin_return_address(0));
 181                         #endif
 182                         return best->Data;
 183                 }
 184
 185                 // Break out of loop
 186                 #if FIRST_FIT
 187                 best = head;
 188                 bestSize = head->Size;
 189                 break;
 190                 #else
 191                 // or check if the block is the best size
 192                 if(bestSize > head->Size) {
 193                         best = head;
 194                         bestSize = head->Size;
 195                 }
 196                 #endif
 197         }
 198
 199         // If no block large enough is found, create one
 200         if(!best)
 201         {
 202                 best = Heap_Extend( Bytes );
 203                 // Check for errors
 204                 if(!best) {
 205                         RELEASE(&giHeapSpinlock);       // Release spinlock
 206                         return NULL;
 207                 }
 208                 // Check size
 209                 if(best->Size == Bytes) {
 210                         RELEASE(&giHeapSpinlock);       // Release spinlock
 211                         #if DEBUG_TRACE
 212                         LOG("RETURN %p, to %p", best->Data, __builtin_return_address(0));
 213                         #endif
 214                         return best->Data;
 215                 }
 216         }
 217
 218         // Split Block
 219         newhead = (void*)( (Uint)best + Bytes );
 220         newfoot = (void*)( (Uint)best + Bytes - sizeof(tHeapFoot) );
 221         foot = (void*)( (Uint)best + best->Size - sizeof(tHeapFoot) );
 222
 223         newfoot->Head = best;   // Create new footer
 224         newfoot->Magic = MAGIC_FOOT;
 225         newhead->Size = best->Size - Bytes;     // Create new header
 226         newhead->Magic = MAGIC_FREE;
 227         foot->Head = newhead;   // Update backlink in old footer
 228         best->Size = Bytes;             // Update size in old header
 229         best->Magic = MAGIC_USED;       // Mark block as used
 230
 231         RELEASE(&giHeapSpinlock);       // Release spinlock
 232         #if DEBUG_TRACE
 233         LOG("RETURN %p, to %p", best->Data, __builtin_return_address(0));
 234         #endif
 235         return best->Data;
 236 }
 237
 238 /**
 239  * \fn void free(void *Ptr)
 240  * \brief Free an allocated memory block
 241  */
 242 void free(void *Ptr)
 243 {
 244         tHeapHead       *head;
 245         tHeapFoot       *foot;
 246
 247         #if DEBUG_TRACE
 248         LOG("Ptr = %p", Ptr);
 249         LOG("Returns to %p", __builtin_return_address(0));
 250         #endif
 251
 252         // Alignment Check
 253         if( (Uint)Ptr & (sizeof(Uint)-1) ) {
 254                 Warning("free - Passed a non-aligned address (%p)", Ptr);
 255                 return;
 256         }
 257
 258         // Sanity check
 259         if((Uint)Ptr < (Uint)gHeapStart || (Uint)Ptr > (Uint)gHeapEnd)
 260         {
 261                 Warning("free - Passed a non-heap address (%p)\n", Ptr);
 262                 return;
 263         }
 264
 265         // Check memory block - Header
 266         head = (void*)( (Uint)Ptr - sizeof(tHeapHead) );
 267         if(head->Magic == MAGIC_FREE) {
 268                 Warning("free - Passed a freed block (%p) by %p", head, __builtin_return_address(0));
 269                 return;
 270         }
 271         if(head->Magic != MAGIC_USED) {
 272                 Warning("free - Magic value is invalid (%p, 0x%x)\n", head, head->Magic);
 273                 return;
 274         }
 275
 276         // Check memory block - Footer
 277         foot = (void*)( (Uint)head + head->Size - sizeof(tHeapFoot) );
 278         if(foot->Head != head) {
 279                 Warning("free - Footer backlink is incorrect (%p, 0x%x)\n", head, foot->Head);
 280                 return;
 281         }
 282         if(foot->Magic != MAGIC_FOOT) {
 283                 Warning("free - Footer magic is invalid (%p, 0x%x)\n", head, foot->Magic);
 284                 return;
 285         }
 286
 287         // Lock
 288         LOCK( &giHeapSpinlock );
 289
 290         // Mark as free
 291         head->Magic = MAGIC_FREE;
 292         // Merge blocks
 293         Heap_Merge( head );
 294
 295         // Release
 296         RELEASE( &giHeapSpinlock );
 297 }
 298
 299 /**
 300  */
 301 void *realloc(void *__ptr, size_t __size)
 302 {
 303         tHeapHead       *head = (void*)( (Uint)__ptr-8 );
 304         tHeapHead       *nextHead;
 305         tHeapFoot       *foot;
 306         Uint    newSize = (__size + sizeof(tHeapFoot)+sizeof(tHeapHead)+BLOCK_SIZE-1)&~(BLOCK_SIZE-1);
 307
 308         // Check for reallocating NULL
 309         if(__ptr == NULL)       return malloc(__size);
 310
 311         // Check if resize is needed
 312         if(newSize <= head->Size)       return __ptr;
 313
 314         // Check if next block is free
 315         nextHead = (void*)( (Uint)head + head->Size );
 316
 317         // Extend into next block
 318         if(nextHead->Magic == MAGIC_FREE && nextHead->Size+head->Size >= newSize)
 319         {
 320                 Uint    size = nextHead->Size + head->Size;
 321                 foot = (void*)( (Uint)nextHead + nextHead->Size - sizeof(tHeapFoot) );
 322                 // Exact Fit
 323                 if(size == newSize) {
 324                         head->Size = newSize;
 325                         foot->Head = head;
 326                         nextHead->Magic = 0;
 327                         nextHead->Size = 0;
 328                         return __ptr;
 329                 }
 330                 // Create a new heap block
 331                 nextHead = (void*)( (Uint)head + newSize );
 332                 nextHead->Size = size - newSize;
 333                 nextHead->Magic = MAGIC_FREE;
 334                 foot->Head = nextHead;  // Edit 2nd footer
 335                 head->Size = newSize;   // Edit first header
 336                 // Create new footer
 337                 foot = (void*)( (Uint)head + newSize - sizeof(tHeapFoot) );
 338                 foot->Head = head;
 339                 foot->Magic = MAGIC_FOOT;
 340                 return __ptr;
 341         }
 342
 343         // Extend downwards?
 344         foot = (void*)( (Uint)head - sizeof(tHeapFoot) );
 345         nextHead = foot->Head;
 346         if(nextHead->Magic == MAGIC_FREE && nextHead->Size+head->Size >= newSize)
 347         {
 348                 Uint    size = nextHead->Size + head->Size;
 349                 // Exact fit
 350                 if(size == newSize)
 351                 {
 352                         Uint    oldDataSize;
 353                         // Set 1st (new/lower) header
 354                         nextHead->Magic = MAGIC_USED;
 355                         nextHead->Size = newSize;
 356                         // Get 2nd (old) footer
 357                         foot = (void*)( (Uint)nextHead + newSize );
 358                         foot->Head = nextHead;
 359                         // Save old data size
 360                         oldDataSize = head->Size - sizeof(tHeapFoot) - sizeof(tHeapHead);
 361                         // Clear old header
 362                         head->Size = 0;
 363                         head->Magic = 0;
 364                         memcpy(nextHead->Data, __ptr, oldDataSize);
 365                 }
 366         }
 367
 368         return NULL;
 369 }
 370
 371 /**
 372  * \fn int IsHeap(void *Ptr)
 373  * \brief Checks if an address is a heap address
 374  */
 375 int IsHeap(void *Ptr)
 376 {
 377         tHeapHead       *head;
 378         if((Uint)Ptr < (Uint)gHeapStart)        return 0;
 379         if((Uint)Ptr > (Uint)gHeapEnd)  return 0;
 380
 381         head = (void*)( (Uint)Ptr - sizeof(tHeapHead) );
 382         if(head->Magic != MAGIC_USED && head->Magic != MAGIC_FREE)
 383                 return 0;
 384
 385         return 1;
 386 }
 387
 388 #if WARNINGS
 389 void Heap_Dump()
 390 {
 391         tHeapHead       *head;
 392         tHeapFoot       *foot;
 393
 394         head = gHeapStart;
 395         while( (Uint)head < (Uint)gHeapEnd )
 396         {
 397                 foot = (void*)( (Uint)head + head->Size - sizeof(tHeapFoot) );
 398                 Log("%p (0x%x): 0x%08lx 0x%lx", head, MM_GetPhysAddr((Uint)head), head->Size, head->Magic);
 399                 Log("%p 0x%lx", foot->Head, foot->Magic);
 400                 Log("");
 401
 402                 // Sanity Check Header
 403                 if(head->Size == 0) {
 404                         Log("HALTED - Size is zero");
 405                         break;
 406                 }
 407                 if(head->Size & (BLOCK_SIZE-1)) {
 408                         Log("HALTED - Size is malaligned");
 409                         break;
 410                 }
 411                 if(head->Magic != MAGIC_FREE && head->Magic != MAGIC_USED) {
 412                         Log("HALTED - Head Magic is Bad");
 413                         break;
 414                 }
 415
 416                 // Check footer
 417                 if(foot->Magic != MAGIC_FOOT) {
 418                         Log("HALTED - Foot Magic is Bad");
 419                         break;
 420                 }
 421                 if(head != foot->Head) {
 422                         Log("HALTED - Footer backlink is invalid");
 423                         break;
 424                 }
 425
 426                 // All OK? Go to next
 427                 head = foot->NextHead;
 428         }
 429 }
 430 #endif