/* malloc.c * */ #ifndef lint #ifdef DEBUGGING #define RCHECK #endif /* * malloc.c (Caltech) 2/21/82 * Chris Kingsley, kingsley@cit-20. * * This is a very fast storage allocator. It allocates blocks of a small * number of different sizes, and keeps free lists of each size. Blocks that * don't exactly fit are passed up to the next larger size. In this * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long. * If PACK_MALLOC is defined, small blocks are 2^n bytes long. * This is designed for use in a program that uses vast quantities of memory, * but bombs when it runs out. */ #include "EXTERN.h" #include "perl.h" #ifdef DEBUGGING #undef DEBUG_m #define DEBUG_m(a) if (debug & 128) a #endif /* I don't much care whether these are defined in sys/types.h--LAW */ #define u_char unsigned char #define u_int unsigned int #define u_short unsigned short /* 286 and atarist like big chunks, which gives too much overhead. */ #if (defined(RCHECK) || defined(I286) || defined(atarist)) && defined(PACK_MALLOC) #undef PACK_MALLOC #endif /* * The description below is applicable if PACK_MALLOC is not defined. * * The overhead on a block is at least 4 bytes. When free, this space * contains a pointer to the next free block, and the bottom two bits must * be zero. When in use, the first byte is set to MAGIC, and the second * byte is the size index. The remaining bytes are for alignment. * If range checking is enabled and the size of the block fits * in two bytes, then the top two bytes hold the size of the requested block * plus the range checking words, and the header word MINUS ONE. */ union overhead { union overhead *ov_next; /* when free */ #if MEM_ALIGNBYTES > 4 double strut; /* alignment problems */ #endif struct { u_char ovu_magic; /* magic number */ u_char ovu_index; /* bucket # */ #ifdef RCHECK u_short ovu_size; /* actual block size */ u_int ovu_rmagic; /* range magic number */ #endif } ovu; #define ov_magic ovu.ovu_magic #define ov_index ovu.ovu_index #define ov_size ovu.ovu_size #define ov_rmagic ovu.ovu_rmagic }; #ifdef DEBUGGING static void botch _((char *s)); #endif static void morecore _((int bucket)); static int findbucket _((union overhead *freep, int srchlen)); #define MAGIC 0xff /* magic # on accounting info */ #define RMAGIC 0x55555555 /* magic # on range info */ #ifdef RCHECK #define RSLOP sizeof (u_int) #else #define RSLOP 0 #endif #ifdef PACK_MALLOC /* * In this case it is assumed that if we do sbrk() in 2K units, we * will get 2K aligned blocks. The bucket number of the given subblock is * on the boundary of 2K block which contains the subblock. * Several following bytes contain the magic numbers for the subblocks * in the block. * * Sizes of chunks are powers of 2 for chunks in buckets <= * MAX_PACKED, after this they are (2^n - sizeof(union overhead)) (to * get alignment right). * * We suppose that starts of all the chunks in a 2K block are in * different 2^n-byte-long chunks. If the top of the last chunk is * aligned on a boundary of 2K block, this means that * sizeof(union overhead)*"number of chunks" < 2^n, or * sizeof(union overhead)*2K < 4^n, or n > 6 + log2(sizeof()/2)/2, if a * chunk of size 2^n - overhead is used. Since this rules out n = 7 * for 8 byte alignment, we specialcase allocation of the first of 16 * 128-byte-long chunks. * * Note that with the above assumption we automatically have enough * place for MAGIC at the start of 2K block. Note also that we * overlay union overhead over the chunk, thus the start of the chunk * is immediately overwritten after freeing. */ # define MAX_PACKED 6 # define MAX_2_POT_ALGO ((1<<(MAX_PACKED + 1)) - M_OVERHEAD) # define TWOK_MASK ((1<<11) - 1) # define TWOK_MASKED(x) ((int)x & ~TWOK_MASK) # define TWOK_SHIFT(x) ((int)x & TWOK_MASK) # define OV_INDEXp(block) ((u_char*)(TWOK_MASKED(block))) # define OV_INDEX(block) (*OV_INDEXp(block)) # define OV_MAGIC(block,bucket) (*(OV_INDEXp(block) + \ (TWOK_SHIFT(block)>>(bucket + 3)) + \ (bucket > MAX_NONSHIFT ? 1 : 0))) # define CHUNK_SHIFT 0 static u_char n_blks[11 - 3] = {224, 120, 62, 31, 16, 8, 4, 2}; static u_short blk_shift[11 - 3] = {256, 128, 64, 32, 16*sizeof(union overhead), 8*sizeof(union overhead), 4*sizeof(union overhead), 2*sizeof(union overhead), # define MAX_NONSHIFT 2 /* Shift 64 greater than chunk 32. */ }; # ifdef DEBUGGING_MSTATS static u_int sbrk_slack; static u_int start_slack; # endif #else /* !PACK_MALLOC */ # define OV_MAGIC(block,bucket) (block)->ov_magic # define OV_INDEX(block) (block)->ov_index # define CHUNK_SHIFT 1 #endif /* !PACK_MALLOC */ # define M_OVERHEAD (sizeof(union overhead) + RSLOP) /* * nextf[i] is the pointer to the next free block of size 2^(i+3). The * smallest allocatable block is 8 bytes. The overhead information * precedes the data area returned to the user. */ #define NBUCKETS 30 static union overhead *nextf[NBUCKETS]; #ifdef USE_PERL_SBRK #define sbrk(a) Perl_sbrk(a) char * Perl_sbrk _((int size)); #else extern char *sbrk(); #endif #ifdef DEBUGGING_MSTATS /* * nmalloc[i] is the difference between the number of mallocs and frees * for a given block size. */ static u_int nmalloc[NBUCKETS]; #endif #ifdef DEBUGGING #define ASSERT(p) if (!(p)) botch(STRINGIFY(p)); else static void botch(s) char *s; { PerlIO_printf(PerlIO_stderr(), "assertion botched: %s\n", s); abort(); } #else #define ASSERT(p) #endif Malloc_t malloc(nbytes) register MEM_SIZE nbytes; { register union overhead *p; register int bucket = 0; register MEM_SIZE shiftr; #ifdef safemalloc #ifdef DEBUGGING MEM_SIZE size = nbytes; #endif #ifdef MSDOS if (nbytes > 0xffff) { PerlIO_printf(PerlIO_stderr(), "Allocation too large: %lx\n", (long)nbytes); my_exit(1); } #endif /* MSDOS */ #ifdef DEBUGGING if ((long)nbytes < 0) croak("panic: malloc"); #endif #endif /* safemalloc */ /* * Convert amount of memory requested into * closest block size stored in hash buckets * which satisfies request. Account for * space used per block for accounting. */ #ifdef PACK_MALLOC if (nbytes > MAX_2_POT_ALGO) { #endif nbytes += M_OVERHEAD; nbytes = (nbytes + 3) &~ 3; #ifdef PACK_MALLOC } else if (nbytes == 0) { nbytes = 1; } #endif shiftr = (nbytes - 1) >> 2; /* apart from this loop, this is O(1) */ while (shiftr >>= 1) bucket++; /* * If nothing in hash bucket right now, * request more memory from the system. */ if (nextf[bucket] == NULL) morecore(bucket); if ((p = (union overhead *)nextf[bucket]) == NULL) { #ifdef safemalloc if (!nomemok) { PerlIO_puts(PerlIO_stderr(),"Out of memory!\n"); my_exit(1); } #else return (NULL); #endif } #ifdef safemalloc DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%lx: (%05d) malloc %ld bytes\n", (unsigned long)(p+1),an++,(long)size)); #endif /* safemalloc */ /* remove from linked list */ #ifdef RCHECK if (*((int*)p) & (sizeof(union overhead) - 1)) PerlIO_printf(PerlIO_stderr(), "Corrupt malloc ptr 0x%lx at 0x%lx\n", (unsigned long)*((int*)p),(unsigned long)p); #endif nextf[bucket] = p->ov_next; OV_MAGIC(p, bucket) = MAGIC; #ifndef PACK_MALLOC OV_INDEX(p) = bucket; #endif #ifdef DEBUGGING_MSTATS nmalloc[bucket]++; #endif #ifdef RCHECK /* * Record allocated size of block and * bound space with magic numbers. */ if (nbytes <= 0x10000) p->ov_size = nbytes - 1; p->ov_rmagic = RMAGIC; *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC; #endif return ((Malloc_t)(p + CHUNK_SHIFT)); } /* * Allocate more memory to the indicated bucket. */ static void morecore(bucket) register int bucket; { register union overhead *op; register int rnu; /* 2^rnu bytes will be requested */ register int nblks; /* become nblks blocks of the desired size */ register MEM_SIZE siz; int slack = 0; if (nextf[bucket]) return; /* * Insure memory is allocated * on a page boundary. Should * make getpageize call? */ #ifndef atarist /* on the atari we dont have to worry about this */ op = (union overhead *)sbrk(0); # ifndef I286 # ifdef PACK_MALLOC if ((int)op & 0x7ff) (void)sbrk(slack = 2048 - ((int)op & 0x7ff)); # else if ((int)op & 0x3ff) (void)sbrk(slack = 1024 - ((int)op & 0x3ff)); # endif # if defined(DEBUGGING_MSTATS) && defined(PACK_MALLOC) sbrk_slack += slack; # endif # else /* The sbrk(0) call on the I286 always returns the next segment */ # endif #endif /* atarist */ #if !(defined(I286) || defined(atarist)) /* take 2k unless the block is bigger than that */ rnu = (bucket <= 8) ? 11 : bucket + 3; #else /* take 16k unless the block is bigger than that (80286s like large segments!), probably good on the atari too */ rnu = (bucket <= 11) ? 14 : bucket + 3; #endif nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */ /* if (rnu < bucket) rnu = bucket; Why anyone needs this? */ op = (union overhead *)sbrk(1L << rnu); /* no more room! */ if ((int)op == -1) return; /* * Round up to minimum allocation size boundary * and deduct from block count to reflect. */ #ifndef I286 # ifdef PACK_MALLOC if ((int)op & 0x7ff) croak("panic: Off-page sbrk"); # endif if ((int)op & 7) { op = (union overhead *)(((MEM_SIZE)op + 8) &~ 7); nblks--; } #else /* Again, this should always be ok on an 80286 */ #endif /* * Add new memory allocated to that on * free list for this hash bucket. */ siz = 1 << (bucket + 3); #ifdef PACK_MALLOC *(u_char*)op = bucket; /* Fill index. */ if (bucket <= MAX_PACKED - 3) { op = (union overhead *) ((char*)op + blk_shift[bucket]); nblks = n_blks[bucket]; # ifdef DEBUGGING_MSTATS start_slack += blk_shift[bucket]; # endif } else if (bucket <= 11 - 1 - 3) { op = (union overhead *) ((char*)op + blk_shift[bucket]); /* nblks = n_blks[bucket]; */ siz -= sizeof(union overhead); } else op++; /* One chunk per block. */ #endif /* !PACK_MALLOC */ nextf[bucket] = op; while (--nblks > 0) { op->ov_next = (union overhead *)((caddr_t)op + siz); op = (union overhead *)((caddr_t)op + siz); } /* Not all sbrks return zeroed memory.*/ op->ov_next = (union overhead *)NULL; #ifdef PACK_MALLOC if (bucket == 7 - 3) { /* Special case, explanation is above. */ union overhead *n_op = nextf[7 - 3]->ov_next; nextf[7 - 3] = (union overhead *)((caddr_t)nextf[7 - 3] - sizeof(union overhead)); nextf[7 - 3]->ov_next = n_op; } #endif /* !PACK_MALLOC */ } Free_t free(mp) Malloc_t mp; { register MEM_SIZE size; register union overhead *op; char *cp = (char*)mp; #ifdef PACK_MALLOC u_char bucket; #endif #ifdef safemalloc DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%lx: (%05d) free\n",(unsigned long)cp,an++)); #endif /* safemalloc */ if (cp == NULL) return; op = (union overhead *)((caddr_t)cp - sizeof (union overhead) * CHUNK_SHIFT); #ifdef PACK_MALLOC bucket = OV_INDEX(op); #endif #ifdef DEBUGGING ASSERT(OV_MAGIC(op, bucket) == MAGIC); /* make sure it was in use */ #else if (OV_MAGIC(op, bucket) != MAGIC) { static bad_free_warn = -1; if (bad_free_warn == -1) { char *pbf = getenv("PERL_BADFREE"); bad_free_warn = (pbf) ? atoi(pbf) : 1; } if (!bad_free_warn) return; #ifdef RCHECK warn("%s free() ignored", op->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad"); #else warn("Bad free() ignored"); #endif return; /* sanity */ } #endif #ifdef RCHECK ASSERT(op->ov_rmagic == RMAGIC); if (OV_INDEX(op) <= 13) ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC); op->ov_rmagic = RMAGIC - 1; #endif ASSERT(OV_INDEX(op) < NBUCKETS); size = OV_INDEX(op); op->ov_next = nextf[size]; nextf[size] = op; #ifdef DEBUGGING_MSTATS nmalloc[size]--; #endif } /* * When a program attempts "storage compaction" as mentioned in the * old malloc man page, it realloc's an already freed block. Usually * this is the last block it freed; occasionally it might be farther * back. We have to search all the free lists for the block in order * to determine its bucket: 1st we make one pass thru the lists * checking only the first block in each; if that fails we search * ``reall_srchlen'' blocks in each list for a match (the variable * is extern so the caller can modify it). If that fails we just copy * however many bytes was given to realloc() and hope it's not huge. */ int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ Malloc_t realloc(mp, nbytes) Malloc_t mp; MEM_SIZE nbytes; { register MEM_SIZE onb; union overhead *op; char *res; register int i; int was_alloced = 0; char *cp = (char*)mp; #ifdef safemalloc #ifdef DEBUGGING MEM_SIZE size = nbytes; #endif #ifdef MSDOS if (nbytes > 0xffff) { PerlIO_printf(PerlIO_stderr(), "Reallocation too large: %lx\n", size); my_exit(1); } #endif /* MSDOS */ if (!cp) return malloc(nbytes); #ifdef DEBUGGING if ((long)nbytes < 0) croak("panic: realloc"); #endif #endif /* safemalloc */ op = (union overhead *)((caddr_t)cp - sizeof (union overhead) * CHUNK_SHIFT); i = OV_INDEX(op); if (OV_MAGIC(op, i) == MAGIC) { was_alloced++; } else { /* * Already free, doing "compaction". * * Search for the old block of memory on the * free list. First, check the most common * case (last element free'd), then (this failing) * the last ``reall_srchlen'' items free'd. * If all lookups fail, then assume the size of * the memory block being realloc'd is the * smallest possible. */ if ((i = findbucket(op, 1)) < 0 && (i = findbucket(op, reall_srchlen)) < 0) i = 0; } onb = (1L << (i + 3)) - #ifdef PACK_MALLOC (i <= (MAX_PACKED - 3) ? 0 : M_OVERHEAD) #else M_OVERHEAD #endif ; /* avoid the copy if same size block */ if (was_alloced && nbytes <= onb && nbytes > (onb >> 1) - M_OVERHEAD) { #ifdef RCHECK /* * Record new allocated size of block and * bound space with magic numbers. */ if (OV_INDEX(op) <= 13) { /* * Convert amount of memory requested into * closest block size stored in hash buckets * which satisfies request. Account for * space used per block for accounting. */ nbytes += M_OVERHEAD; nbytes = (nbytes + 3) &~ 3; op->ov_size = nbytes - 1; *((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC; } #endif res = cp; } else { if ((res = (char*)malloc(nbytes)) == NULL) return (NULL); if (cp != res) /* common optimization */ Copy(cp, res, (MEM_SIZE)(nbytesov_next) { if (p == freep) return (i); j++; } } return (-1); } Malloc_t calloc(elements, size) register MEM_SIZE elements; register MEM_SIZE size; { long sz = elements * size; Malloc_t p = malloc(sz); if (p) { memset((void*)p, 0, sz); } return p; } #ifdef DEBUGGING_MSTATS /* * mstats - print out statistics about malloc * * Prints two lines of numbers, one showing the length of the free list * for each size category, the second showing the number of mallocs - * frees for each size category. */ void dump_mstats(s) char *s; { register int i, j; register union overhead *p; int topbucket=0, totfree=0, totused=0; u_int nfree[NBUCKETS]; for (i=0; i < NBUCKETS; i++) { for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) ; nfree[i] = j; totfree += nfree[i] * (1 << (i + 3)); totused += nmalloc[i] * (1 << (i + 3)); if (nfree[i] || nmalloc[i]) topbucket = i; } if (s) PerlIO_printf(PerlIO_stderr(), "Memory allocation statistics %s (buckets 8..%d)\n", s, (1 << (topbucket + 3)) ); PerlIO_printf(PerlIO_stderr(), " %7d free: ", totfree); for (i=0; i <= topbucket; i++) { PerlIO_printf(PerlIO_stderr(), (i<5)?" %5d":" %3d", nfree[i]); } PerlIO_printf(PerlIO_stderr(), "\n %7d used: ", totused); for (i=0; i <= topbucket; i++) { PerlIO_printf(PerlIO_stderr(), (i<5)?" %5d":" %3d", nmalloc[i]); } PerlIO_printf(PerlIO_stderr(), "\n"); #ifdef PACK_MALLOC if (sbrk_slack || start_slack) { PerlIO_printf(PerlIO_stderr(), "Odd ends: %7d bytes from sbrk(), %7d from malloc.\n", sbrk_slack, start_slack); } #endif } #else void dump_mstats(s) char *s; { } #endif #endif /* lint */ #ifdef USE_PERL_SBRK # ifdef NeXT # define PERL_SBRK_VIA_MALLOC # endif # ifdef PERL_SBRK_VIA_MALLOC # ifdef HIDEMYMALLOC # undef malloc # else # include "Error: -DPERL_SBRK_VIA_MALLOC requires -DHIDEMYMALLOC" # endif /* it may seem schizophrenic to use perl's malloc and let it call system */ /* malloc, the reason for that is only the 3.2 version of the OS that had */ /* frequent core dumps within nxzonefreenolock. This sbrk routine put an */ /* end to the cores */ # define SYSTEM_ALLOC(a) malloc(a) # endif /* PERL_SBRK_VIA_MALLOC */ static IV Perl_sbrk_oldchunk; static long Perl_sbrk_oldsize; # define PERLSBRK_32_K (1<<15) # define PERLSBRK_64_K (1<<16) char * Perl_sbrk(size) int size; { IV got; int small, reqsize; if (!size) return 0; #ifdef safemalloc reqsize = size; /* just for the DEBUG_m statement */ #endif if (size <= Perl_sbrk_oldsize) { got = Perl_sbrk_oldchunk; Perl_sbrk_oldchunk += size; Perl_sbrk_oldsize -= size; } else { if (size >= PERLSBRK_32_K) { small = 0; } else { #ifndef safemalloc reqsize = size; #endif size = PERLSBRK_64_K; small = 1; } got = (IV)SYSTEM_ALLOC(size); if (small) { /* Chunk is small, register the rest for future allocs. */ Perl_sbrk_oldchunk = got + reqsize; Perl_sbrk_oldsize = size - reqsize; } } #ifdef safemalloc DEBUG_m(PerlIO_printf(PerlIO_stderr(), "sbrk malloc size %ld (reqsize %ld), left size %ld, give addr 0x%lx\n", size, reqsize, Perl_sbrk_oldsize, got)); #endif return (void *)got; } #endif /* ! defined USE_PERL_SBRK */