Kernel/heap.c

   1 /*
   2  * AcessOS Microkernel Version
   3  * heap.c
   4  */
   5 #include <acess.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_INIT_SIZE  0x8000  // 32 KiB
  14 #define BLOCK_SIZE      (sizeof(void*))*8       // 8 Machine Words
  15 #define COMPACT_HEAP    0       // Use 4 byte header?
  16 #define FIRST_FIT       0
  17
  18 #define MAGIC_FOOT      0x2ACE5505
  19 #define MAGIC_FREE      0xACE55000
  20 #define MAGIC_USED      0x862B0505      // MAGIC_FOOT ^ MAGIC_FREE
  21
  22 // === PROTOTYPES ===
  23 void    Heap_Install(void);
  24 void    *Heap_Extend(int Bytes);
  25 void    *Heap_Merge(tHeapHead *Head);
  26 void    *malloc(size_t Bytes);
  27 void    free(void *Ptr);
  28 void    Heap_Dump(void);
  29
  30 // === GLOBALS ===
  31 tSpinlock       glHeap;
  32 void    *gHeapStart;
  33 void    *gHeapEnd;
  34
  35 // === CODE ===
  36 void Heap_Install(void)
  37 {
  38         gHeapStart      = (void*)MM_KHEAP_BASE;
  39         gHeapEnd        = (void*)MM_KHEAP_BASE;
  40         Heap_Extend(HEAP_INIT_SIZE);
  41 }
  42
  43 /**
  44  * \fn void *Heap_Extend(int Bytes)
  45  * \brief Extend the size of the heap
  46  */
  47 void *Heap_Extend(int Bytes)
  48 {
  49         Uint    i;
  50         tHeapHead       *head = gHeapEnd;
  51         tHeapFoot       *foot;
  52
  53         // Bounds Check
  54         if( (tVAddr)gHeapEnd == MM_KHEAP_MAX )
  55                 return NULL;
  56
  57         // Bounds Check
  58         if( (tVAddr)gHeapEnd + ((Bytes+0xFFF)&~0xFFF) > MM_KHEAP_MAX ) {
  59                 Bytes = MM_KHEAP_MAX - (tVAddr)gHeapEnd;
  60                 return NULL;
  61         }
  62
  63         // Heap expands in pages
  64         for(i=0;i<(Bytes+0xFFF)>>12;i++)
  65                 MM_Allocate( (tVAddr)gHeapEnd+(i<<12) );
  66
  67         // Increas heap end
  68         gHeapEnd += i << 12;
  69
  70         // Create Block
  71         head->Size = (Bytes+0xFFF)&~0xFFF;
  72         head->Magic = MAGIC_FREE;
  73         foot = (void*)( (Uint)gHeapEnd - sizeof(tHeapFoot) );
  74         foot->Head = head;
  75         foot->Magic = MAGIC_FOOT;
  76
  77         return Heap_Merge(head);        // Merge with previous block
  78 }
  79
  80 /**
  81  * \fn void *Heap_Merge(tHeapHead *Head)
  82  * \brief Merges two ajacent heap blocks
  83  */
  84 void *Heap_Merge(tHeapHead *Head)
  85 {
  86         tHeapFoot       *foot;
  87         tHeapFoot       *thisFoot;
  88         tHeapHead       *head;
  89
  90         //Log("Heap_Merge: (Head=%p)", Head);
  91
  92         thisFoot = (void*)( (Uint)Head + Head->Size - sizeof(tHeapFoot) );
  93         if((Uint)thisFoot > (Uint)gHeapEnd)     return NULL;
  94
  95         // Merge Left (Down)
  96         foot = (void*)( (Uint)Head - sizeof(tHeapFoot) );
  97         if( ((Uint)foot < (Uint)gHeapEnd && (Uint)foot > (Uint)gHeapStart)
  98         && foot->Head->Magic == MAGIC_FREE) {
  99                 foot->Head->Size += Head->Size; // Increase size
 100                 thisFoot->Head = foot->Head;    // Change backlink
 101                 Head->Magic = 0;        // Clear old head
 102                 Head->Size = 0;
 103                 Head = foot->Head;      // Save new head address
 104                 foot->Head = NULL;      // Clear central footer
 105                 foot->Magic = 0;
 106         }
 107
 108         // Merge Right (Upwards)
 109         head = (void*)( (Uint)Head + Head->Size );
 110         if((Uint)head < (Uint)gHeapEnd && head->Magic == MAGIC_FREE)
 111         {
 112                 Head->Size += head->Size;
 113                 foot = (void*)( (Uint)Head + Head->Size - sizeof(tHeapFoot) );
 114                 foot->Head = Head;      // Update Backlink
 115                 thisFoot->Head = NULL;  // Clear old footer
 116                 thisFoot->Magic = 0;
 117                 head->Size = 0;         // Clear old header
 118                 head->Magic = 0;
 119         }
 120
 121         // Return new address
 122         return Head;
 123 }
 124
 125 /**
 126  * \fn void *malloc(size_t Bytes)
 127  * \brief Allocate memory from the heap
 128  */
 129 void *malloc(size_t Bytes)
 130 {
 131         tHeapHead       *head, *newhead;
 132         tHeapFoot       *foot, *newfoot;
 133         tHeapHead       *best = NULL;
 134         Uint    bestSize = 0;   // Speed hack
 135
 136         // Get required size
 137         Bytes = (Bytes + sizeof(tHeapHead) + sizeof(tHeapFoot) + BLOCK_SIZE-1) & ~(BLOCK_SIZE-1);
 138
 139         // Lock Heap
 140         LOCK(&glHeap);
 141
 142         // Traverse Heap
 143         for( head = gHeapStart;
 144                 (Uint)head < (Uint)gHeapEnd;
 145                 head = (void*)((Uint)head + head->Size)
 146                 )
 147         {
 148                 // Alignment Check
 149                 if( head->Size & (BLOCK_SIZE-1) ) {
 150                         #if WARNINGS
 151                         Log_Warning("Heap", "Size of heap address %p is invalid not aligned (0x%x)", head, head->Size);
 152                         Heap_Dump();
 153                         #endif
 154                         RELEASE(&glHeap);
 155                         return NULL;
 156                 }
 157
 158                 // Check if allocated
 159                 if(head->Magic == MAGIC_USED)   continue;
 160                 // Error check
 161                 if(head->Magic != MAGIC_FREE)   {
 162                         #if WARNINGS
 163                         Log_Warning("Heap", "Magic of heap address %p is invalid (0x%x)", head, head->Magic);
 164                         Heap_Dump();
 165                         #endif
 166                         RELEASE(&glHeap);       // Release spinlock
 167                         return NULL;
 168                 }
 169
 170                 // Size check
 171                 if(head->Size < Bytes)  continue;
 172
 173                 // Perfect fit
 174                 if(head->Size == Bytes) {
 175                         head->Magic = MAGIC_USED;
 176                         RELEASE(&glHeap);       // Release spinlock
 177                         #if DEBUG_TRACE
 178                         Log("[Heap   ] Malloc'd %p (%i bytes), returning to %p", head->Data, head->Size,  __builtin_return_address(0));
 179                         #endif
 180                         RELEASE(&glHeap);
 181                         return head->Data;
 182                 }
 183
 184                 // Break out of loop
 185                 #if FIRST_FIT
 186                 best = head;
 187                 bestSize = head->Size;
 188                 break;
 189                 #else
 190                 // or check if the block is the best size
 191                 if(bestSize > head->Size) {
 192                         best = head;
 193                         bestSize = head->Size;
 194                 }
 195                 #endif
 196         }
 197
 198         // If no block large enough is found, create one
 199         if(!best)
 200         {
 201                 best = Heap_Extend( Bytes );
 202                 // Check for errors
 203                 if(!best) {
 204                         RELEASE(&glHeap);       // Release spinlock
 205                         return NULL;
 206                 }
 207                 // Check size
 208                 if(best->Size == Bytes) {
 209                         best->Magic = MAGIC_USED;       // Mark block as used
 210                         #if DEBUG_TRACE
 211                         Log("[Heap   ] Malloc'd %p (%i bytes), returning to %p", best->Data, best->Size, __builtin_return_address(0));
 212                         #endif
 213                         RELEASE(&glHeap);       // Release spinlock
 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(&glHeap);       // Release spinlock
 232         #if DEBUG_TRACE
 233         Log("[Heap   ] Malloc'd %p (%i bytes), returning to %p", best->Data, best->Size, __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_Log("Heap", "free: Ptr = %p", Ptr);
 249         Log_Log("Heap", "free: Returns to %p", __builtin_return_address(0));
 250         #endif
 251
 252         // Alignment Check
 253         if( (Uint)Ptr & (sizeof(Uint)-1) ) {
 254                 Log_Warning("Heap", "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                 Log_Warning("Heap", "free - Passed a non-heap address (%p < %p < %p)\n",
 262                         gHeapStart, Ptr, gHeapEnd);
 263                 return;
 264         }
 265
 266         // Check memory block - Header
 267         head = (void*)( (Uint)Ptr - sizeof(tHeapHead) );
 268         if(head->Magic == MAGIC_FREE) {
 269                 Log_Warning("Heap", "free - Passed a freed block (%p) by %p", head, __builtin_return_address(0));
 270                 return;
 271         }
 272         if(head->Magic != MAGIC_USED) {
 273                 Log_Warning("Heap", "free - Magic value is invalid (%p, 0x%x)\n", head, head->Magic);
 274                 return;
 275         }
 276
 277         // Check memory block - Footer
 278         foot = (void*)( (Uint)head + head->Size - sizeof(tHeapFoot) );
 279         if(foot->Head != head) {
 280                 Log_Warning("Heap", "free - Footer backlink is incorrect (%p, 0x%x)\n", head, foot->Head);
 281                 return;
 282         }
 283         if(foot->Magic != MAGIC_FOOT) {
 284                 Log_Warning("Heap", "free - Footer magic is invalid (%p, %p = 0x%x)\n", head, &foot->Magic, foot->Magic);
 285                 return;
 286         }
 287
 288         // Lock
 289         LOCK( &glHeap );
 290
 291         // Mark as free
 292         head->Magic = MAGIC_FREE;
 293         // Merge blocks
 294         Heap_Merge( head );
 295
 296         // Release
 297         RELEASE( &glHeap );
 298 }
 299
 300 /**
 301  */
 302 void *realloc(void *__ptr, size_t __size)
 303 {
 304         tHeapHead       *head = (void*)( (Uint)__ptr-8 );
 305         tHeapHead       *nextHead;
 306         tHeapFoot       *foot;
 307         Uint    newSize = (__size + sizeof(tHeapFoot)+sizeof(tHeapHead)+BLOCK_SIZE-1)&~(BLOCK_SIZE-1);
 308
 309         // Check for reallocating NULL
 310         if(__ptr == NULL)       return malloc(__size);
 311
 312         // Check if resize is needed
 313         if(newSize <= head->Size)       return __ptr;
 314
 315         // Check if next block is free
 316         nextHead = (void*)( (Uint)head + head->Size );
 317
 318         // Extend into next block
 319         if(nextHead->Magic == MAGIC_FREE && nextHead->Size+head->Size >= newSize)
 320         {
 321                 Uint    size = nextHead->Size + head->Size;
 322                 foot = (void*)( (Uint)nextHead + nextHead->Size - sizeof(tHeapFoot) );
 323                 // Exact Fit
 324                 if(size == newSize) {
 325                         head->Size = newSize;
 326                         foot->Head = head;
 327                         nextHead->Magic = 0;
 328                         nextHead->Size = 0;
 329                         return __ptr;
 330                 }
 331                 // Create a new heap block
 332                 nextHead = (void*)( (Uint)head + newSize );
 333                 nextHead->Size = size - newSize;
 334                 nextHead->Magic = MAGIC_FREE;
 335                 foot->Head = nextHead;  // Edit 2nd footer
 336                 head->Size = newSize;   // Edit first header
 337                 // Create new footer
 338                 foot = (void*)( (Uint)head + newSize - sizeof(tHeapFoot) );
 339                 foot->Head = head;
 340                 foot->Magic = MAGIC_FOOT;
 341                 return __ptr;
 342         }
 343
 344         // Extend downwards?
 345         foot = (void*)( (Uint)head - sizeof(tHeapFoot) );
 346         nextHead = foot->Head;
 347         if(nextHead->Magic == MAGIC_FREE && nextHead->Size+head->Size >= newSize)
 348         {
 349                 Uint    size = nextHead->Size + head->Size;
 350                 // Inexact fit, split things up
 351                 if(size > newSize)
 352                 {
 353                         // TODO
 354                         Warning("[Heap   ] TODO: Space efficient realloc when new size is smaller");
 355                 }
 356
 357                 // Exact fit
 358                 if(size >= newSize)
 359                 {
 360                         Uint    oldDataSize;
 361                         // Set 1st (new/lower) header
 362                         nextHead->Magic = MAGIC_USED;
 363                         nextHead->Size = newSize;
 364                         // Get 2nd (old) footer
 365                         foot = (void*)( (Uint)nextHead + newSize );
 366                         foot->Head = nextHead;
 367                         // Save old data size
 368                         oldDataSize = head->Size - sizeof(tHeapFoot) - sizeof(tHeapHead);
 369                         // Clear old header
 370                         head->Size = 0;
 371                         head->Magic = 0;
 372                         // Copy data
 373                         memcpy(nextHead->Data, __ptr, oldDataSize);
 374                         // Return
 375                         return nextHead->Data;
 376                 }
 377                 // On to the expensive then
 378         }
 379
 380         // Well, darn
 381         nextHead = malloc( __size );
 382         nextHead -= 1;
 383
 384         memcpy(
 385                 nextHead->Data,
 386                 __ptr,
 387                 head->Size - sizeof(tHeapFoot) - sizeof(tHeapHead)
 388                 );
 389
 390         free(__ptr);
 391
 392         return nextHead->Data;
 393 }
 394
 395 /**
 396  * \fn void *calloc(size_t num, size_t size)
 397  * \brief Allocate and Zero a buffer in memory
 398  * \param num   Number of elements
 399  * \param size  Size of each element
 400  */
 401 void *calloc(size_t num, size_t size)
 402 {
 403         void    *ret = malloc(num*size);
 404         if(ret == NULL) return NULL;
 405
 406         memset( ret, 0, num*size );
 407
 408         return ret;
 409 }
 410
 411 /**
 412  * \fn int IsHeap(void *Ptr)
 413  * \brief Checks if an address is a heap pointer
 414  */
 415 int IsHeap(void *Ptr)
 416 {
 417         tHeapHead       *head;
 418         if((Uint)Ptr < (Uint)gHeapStart)        return 0;
 419         if((Uint)Ptr > (Uint)gHeapEnd)  return 0;
 420         if((Uint)Ptr & (sizeof(Uint)-1))        return 0;
 421
 422         head = (void*)( (Uint)Ptr - sizeof(tHeapHead) );
 423         if(head->Magic != MAGIC_USED && head->Magic != MAGIC_FREE)
 424                 return 0;
 425
 426         return 1;
 427 }
 428
 429 #if WARNINGS
 430 void Heap_Dump(void)
 431 {
 432         tHeapHead       *head;
 433         tHeapFoot       *foot;
 434
 435         head = gHeapStart;
 436         while( (Uint)head < (Uint)gHeapEnd )
 437         {
 438                 foot = (void*)( (Uint)head + head->Size - sizeof(tHeapFoot) );
 439                 Log_Log("Heap", "%p (0x%x): 0x%08lx 0x%lx",
 440                         head, MM_GetPhysAddr((Uint)head), head->Size, head->Magic);
 441                 Log_Log("Heap", "%p 0x%lx", foot->Head, foot->Magic);
 442                 Log_Log("Heap", "");
 443
 444                 // Sanity Check Header
 445                 if(head->Size == 0) {
 446                         Log_Warning("Heap", "HALTED - Size is zero");
 447                         break;
 448                 }
 449                 if(head->Size & (BLOCK_SIZE-1)) {
 450                         Log_Warning("Heap", "HALTED - Size is malaligned");
 451                         break;
 452                 }
 453                 if(head->Magic != MAGIC_FREE && head->Magic != MAGIC_USED) {
 454                         Log_Warning("Heap", "HALTED - Head Magic is Bad");
 455                         break;
 456                 }
 457
 458                 // Check footer
 459                 if(foot->Magic != MAGIC_FOOT) {
 460                         Log_Warning("Heap", "HALTED - Foot Magic is Bad");
 461                         break;
 462                 }
 463                 if(head != foot->Head) {
 464                         Log_Warning("Heap", "HALTED - Footer backlink is invalid");
 465                         break;
 466                 }
 467
 468                 // All OK? Go to next
 469                 head = foot->NextHead;
 470         }
 471 }
 472 #endif
 473
 474 // === EXPORTS ===
 475 EXPORT(malloc);
 476 EXPORT(realloc);
 477 EXPORT(free);