/* * libc/stdlib/malloc/malloc.h -- small malloc implementation * * Copyright (C) 2002 NEC Corporation * Copyright (C) 2002 Miles Bader * * This file is subject to the terms and conditions of the GNU Lesser * General Public License. See the file COPYING.LIB in the main * directory of this archive for more details. * * Written by Miles Bader */ /* The alignment we guarantee for malloc return values. We prefer this to be at least sizeof (size_t) bytes because (a) we have to allocate that many bytes for the header anyway and (b) guaranteeing word alignment can be a significant win on targets like m68k and Coldfire, where __alignof__(double) == 2. */ #define MALLOC_ALIGNMENT \ (__alignof__ (double) > sizeof (size_t) ? __alignof__ (double) : sizeof (size_t)) /* The system pagesize... */ #define MALLOC_PAGE_SIZE sysconf(_SC_PAGESIZE) /* The minimum size of block we request from the the system to extend the heap for small allocations (we may request a bigger block if necessary to satisfy a particularly big request). */ #define MALLOC_HEAP_EXTEND_SIZE MALLOC_PAGE_SIZE /* When a heap free-area grows above this size, try to unmap it, releasing the memory back to the system. */ #define MALLOC_UNMAP_THRESHOLD (8*MALLOC_PAGE_SIZE) /* When unmapping a free-area, retain this many bytes if it's the only one, to avoid completely emptying the heap. This is only a heuristic -- the existance of another free area, even if it's smaller than MALLOC_MIN_SIZE, will cause us not to reserve anything. */ #define MALLOC_MIN_SIZE (2*MALLOC_PAGE_SIZE) /* When realloc shrinks an allocation, it only does so if more than this many bytes will be freed; it must at at least HEAP_MIN_SIZE. Larger values increase speed (by reducing heap fragmentation) at the expense of space. */ #define MALLOC_REALLOC_MIN_FREE_SIZE (HEAP_MIN_SIZE + 16) /* For systems with an MMU, use sbrk to map/unmap memory for the malloc heap, instead of mmap/munmap. This is a tradeoff -- sbrk is faster than mmap/munmap, and guarantees contiguous allocation, but is also less flexible, and causes the heap to only be shrinkable from the end. */ #ifdef __ARCH_USE_MMU__ # define MALLOC_USE_SBRK #endif /* The current implementation of munmap in uClinux doesn't work correctly: it requires that ever call to munmap exactly match a corresponding call to mmap (that is, it doesn't allow you to unmap only part of a previously allocated block, or to unmap two contiguous blocks with a single call to munmap). This behavior is broken, and uClinux should be fixed; however, until it is, we add code to work around the problem in malloc. */ #ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__ /* A structure recording a block of memory mmapped by malloc. */ struct malloc_mmb { void *mem; /* the mmapped block */ size_t size; /* its size */ struct malloc_mmb *next; }; /* A list of all malloc_mmb structures describing blocks that malloc has mmapped, ordered by the block address. */ extern struct malloc_mmb *__malloc_mmapped_blocks; /* A heap used for allocating malloc_mmb structures. We could allocate them from the main heap, but that tends to cause heap fragmentation in annoying ways. */ extern struct heap_free_area *__malloc_mmb_heap; /* Define MALLOC_MMB_DEBUGGING to cause malloc to emit debugging info about about mmap block allocation/freeing by the `uclinux broken munmap' code to stderr, when the variable __malloc_mmb_debug is set to true. */ #ifdef MALLOC_MMB_DEBUGGING # include extern int __malloc_mmb_debug; # define MALLOC_MMB_DEBUG(indent, fmt, args...) \ (__malloc_mmb_debug ? __malloc_debug_printf (indent, fmt , ##args) : 0) # define MALLOC_MMB_DEBUG_INDENT(indent) \ (__malloc_mmb_debug ? __malloc_debug_indent (indent) : 0) # ifndef MALLOC_DEBUGGING # define MALLOC_DEBUGGING # endif #else /* !MALLOC_MMB_DEBUGGING */ # define MALLOC_MMB_DEBUG(fmt, args...) (void)0 # define MALLOC_MMB_DEBUG_INDENT(indent) (void)0 #endif /* MALLOC_MMB_DEBUGGING */ #endif /* __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */ /* The size of a malloc allocation is stored in a size_t word MALLOC_HEADER_SIZE bytes prior to the start address of the allocation: +--------+---------+-------------------+ | SIZE |(unused) | allocation ... | +--------+---------+-------------------+ ^ BASE ^ ADDR ^ ADDR - MALLOC_HEADER_SIZE */ /* The amount of extra space used by the malloc header. */ #define MALLOC_HEADER_SIZE \ (MALLOC_ALIGNMENT < sizeof (size_t) \ ? sizeof (size_t) \ : MALLOC_ALIGNMENT) /* Set up the malloc header, and return the user address of a malloc block. */ #define MALLOC_SETUP(base, size) \ (MALLOC_SET_SIZE (base, size), (void *)((char *)base + MALLOC_HEADER_SIZE)) /* Set the size of a malloc allocation, given the base address. */ #define MALLOC_SET_SIZE(base, size) (*(size_t *)(base) = (size)) /* Return base-address of a malloc allocation, given the user address. */ #define MALLOC_BASE(addr) ((void *)((char *)addr - MALLOC_HEADER_SIZE)) /* Return the size of a malloc allocation, given the user address. */ #define MALLOC_SIZE(addr) (*(size_t *)MALLOC_BASE(addr)) #include #ifdef __UCLIBC_HAS_THREADS__ # define MALLOC_USE_LOCKING #endif #ifdef MALLOC_USE_SBRK /* This lock is used to serialize uses of the `sbrk' function (in both malloc and free, sbrk may be used several times in succession, and things will break if these multiple calls are interleaved with another thread's use of sbrk!). */ __UCLIBC_MUTEX_EXTERN(__malloc_sbrk_lock); # define __malloc_lock_sbrk() __UCLIBC_MUTEX_LOCK_CANCEL_UNSAFE (__malloc_sbrk_lock) # define __malloc_unlock_sbrk() __UCLIBC_MUTEX_UNLOCK_CANCEL_UNSAFE (__malloc_sbrk_lock) #else # define __malloc_lock_sbrk() (void)0 # define __malloc_unlock_sbrk() (void)0 #endif /* MALLOC_USE_SBRK */ /* Define MALLOC_DEBUGGING to cause malloc to emit debugging info to stderr when the variable __malloc_debug is set to true. */ #ifdef MALLOC_DEBUGGING extern void __malloc_debug_init (void) attribute_hidden; /* The number of spaces in a malloc debug indent level. */ #define MALLOC_DEBUG_INDENT_SIZE 3 extern int __malloc_debug attribute_hidden, __malloc_check attribute_hidden; # define MALLOC_DEBUG(indent, fmt, args...) \ (__malloc_debug ? __malloc_debug_printf (indent, fmt , ##args) : 0) # define MALLOC_DEBUG_INDENT(indent) \ (__malloc_debug ? __malloc_debug_indent (indent) : 0) extern int __malloc_debug_cur_indent attribute_hidden; /* Print FMT and args indented at the current debug print level, followed by a newline, and change the level by INDENT. */ extern void __malloc_debug_printf (int indent, const char *fmt, ...) attribute_hidden; /* Change the current debug print level by INDENT, and return the value. */ #define __malloc_debug_indent(indent) (__malloc_debug_cur_indent += indent) /* Set the current debug print level to LEVEL. */ #define __malloc_debug_set_indent(level) (__malloc_debug_cur_indent = level) #else /* !MALLOC_DEBUGGING */ # define MALLOC_DEBUG(fmt, args...) (void)0 # define MALLOC_DEBUG_INDENT(indent) (void)0 #endif /* MALLOC_DEBUGGING */ /* Return SZ rounded down to POWER_OF_2_SIZE (which must be power of 2). */ #define MALLOC_ROUND_DOWN(sz, power_of_2_size) \ ((sz) & ~(power_of_2_size - 1)) /* Return SZ rounded to POWER_OF_2_SIZE (which must be power of 2). */ #define MALLOC_ROUND_UP(sz, power_of_2_size) \ MALLOC_ROUND_DOWN ((sz) + (power_of_2_size - 1), (power_of_2_size)) /* Return SZ rounded down to a multiple MALLOC_PAGE_SIZE. */ #define MALLOC_ROUND_DOWN_TO_PAGE_SIZE(sz) \ MALLOC_ROUND_DOWN (sz, MALLOC_PAGE_SIZE) /* Return SZ rounded up to a multiple MALLOC_PAGE_SIZE. */ #define MALLOC_ROUND_UP_TO_PAGE_SIZE(sz) \ MALLOC_ROUND_UP (sz, MALLOC_PAGE_SIZE) /* The malloc heap. */ extern struct heap_free_area *__malloc_heap attribute_hidden; #ifdef __UCLIBC_HAS_THREADS__ __UCLIBC_MUTEX_EXTERN(__malloc_heap_lock) # ifndef __UCLIBC_HAS_LINUXTHREADS__ attribute_hidden # endif ; # ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__ __UCLIBC_MUTEX_EXTERN(__malloc_mmb_heap_lock) # ifndef __UCLIBC_HAS_LINUXTHREADS__ attribute_hidden # endif ; # endif #endif