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303 lines
8.3 KiB
C
303 lines
8.3 KiB
C
/*
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* This module derived from code donated to the FreeBSD Project by
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* Matthew Dillon <dillon@backplane.com>
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*
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* Copyright (c) 1998 The FreeBSD Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* LIB/MEMORY/ZALLOC.C - self contained low-overhead memory pool/allocation
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* subsystem
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*
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* This subsystem implements memory pools and memory allocation
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* routines.
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*
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* Pools are managed via a linked list of 'free' areas. Allocating
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* memory creates holes in the freelist, freeing memory fills them.
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* Since the freelist consists only of free memory areas, it is possible
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* to allocate the entire pool without incuring any structural overhead.
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*
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* The system works best when allocating similarly-sized chunks of
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* memory. Care must be taken to avoid fragmentation when
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* allocating/deallocating dissimilar chunks.
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*
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* When a memory pool is first allocated, the entire pool is marked as
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* allocated. This is done mainly because we do not want to modify any
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* portion of a pool's data area until we are given permission. The
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* caller must explicitly deallocate portions of the pool to make them
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* available.
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*
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* z[n]xalloc() works like z[n]alloc() but the allocation is made from
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* within the specified address range. If the segment could not be
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* allocated, NULL is returned. WARNING! The address range will be
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* aligned to an 8 or 16 byte boundry depending on the cpu so if you
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* give an unaligned address range, unexpected results may occur.
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*
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* If a standard allocation fails, the reclaim function will be called
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* to recover some space. This usually causes other portions of the
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* same pool to be released. Memory allocations at this low level
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* should not block but you can do that too in your reclaim function
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* if you want. Reclaim does not function when z[n]xalloc() is used,
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* only for z[n]alloc().
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*
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* Allocation and frees of 0 bytes are valid operations.
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*/
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#include "zalloc_defs.h"
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/*
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* znalloc() - allocate memory (without zeroing) from pool. Call reclaim
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* and retry if appropriate, return NULL if unable to allocate
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* memory.
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*/
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void *
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znalloc(MemPool *mp, iaddr_t bytes)
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{
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/*
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* align according to pool object size (can be 0). This is
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* inclusive of the MEMNODE_SIZE_MASK minimum alignment.
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*
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*/
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bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
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if (bytes == 0)
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return((void *)-1);
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/*
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* locate freelist entry big enough to hold the object. If all objects
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* are the same size, this is a constant-time function.
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*/
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if (bytes <= mp->mp_Size - mp->mp_Used) {
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MemNode **pmn;
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MemNode *mn;
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for (pmn = &mp->mp_First; (mn=*pmn) != NULL; pmn = &mn->mr_Next) {
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if (bytes > mn->mr_Bytes)
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continue;
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/*
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* Cut a chunk of memory out of the beginning of this
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* block and fixup the link appropriately.
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*/
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{
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char *ptr = (char *)mn;
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if (mn->mr_Bytes == bytes) {
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*pmn = mn->mr_Next;
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} else {
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mn = (MemNode *)((char *)mn + bytes);
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mn->mr_Next = ((MemNode *)ptr)->mr_Next;
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mn->mr_Bytes = ((MemNode *)ptr)->mr_Bytes - bytes;
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*pmn = mn;
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}
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mp->mp_Used += bytes;
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return(ptr);
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}
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}
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}
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/*
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* Memory pool is full, return NULL.
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*/
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return(NULL);
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}
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/*
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* zfree() - free previously allocated memory
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*/
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void
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zfree(MemPool *mp, void *ptr, iaddr_t bytes)
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{
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/*
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* align according to pool object size (can be 0). This is
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* inclusive of the MEMNODE_SIZE_MASK minimum alignment.
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*/
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bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
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if (bytes == 0)
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return;
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/*
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* panic if illegal pointer
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*/
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if ((char *)ptr < (char *)mp->mp_Base ||
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(char *)ptr + bytes > (char *)mp->mp_End ||
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((iaddr_t)ptr & MEMNODE_SIZE_MASK) != 0)
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panic("zfree(%p,%d): wild pointer", ptr, bytes);
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/*
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* free the segment
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*/
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{
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MemNode **pmn;
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MemNode *mn;
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mp->mp_Used -= bytes;
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for (pmn = &mp->mp_First; (mn = *pmn) != NULL; pmn = &mn->mr_Next) {
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/*
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* If area between last node and current node
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* - check range
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* - check merge with next area
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* - check merge with previous area
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*/
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if ((char *)ptr <= (char *)mn) {
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/*
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* range check
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*/
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if ((char *)ptr + bytes > (char *)mn)
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panic("zfree(%p,%d): corrupt memlist1",ptr, bytes);
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/*
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* merge against next area or create independant area
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*/
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if ((char *)ptr + bytes == (char *)mn) {
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((MemNode *)ptr)->mr_Next = mn->mr_Next;
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((MemNode *)ptr)->mr_Bytes= bytes + mn->mr_Bytes;
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} else {
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((MemNode *)ptr)->mr_Next = mn;
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((MemNode *)ptr)->mr_Bytes= bytes;
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}
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*pmn = mn = (MemNode *)ptr;
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/*
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* merge against previous area (if there is a previous
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* area).
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*/
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if (pmn != &mp->mp_First) {
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if ((char*)pmn + ((MemNode*)pmn)->mr_Bytes == (char*)ptr) {
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((MemNode *)pmn)->mr_Next = mn->mr_Next;
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((MemNode *)pmn)->mr_Bytes += mn->mr_Bytes;
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mn = (MemNode *)pmn;
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}
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}
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return;
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/* NOT REACHED */
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}
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if ((char *)ptr < (char *)mn + mn->mr_Bytes)
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panic("zfree(%p,%d): corrupt memlist2", ptr, bytes);
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}
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/*
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* We are beyond the last MemNode, append new MemNode. Merge against
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* previous area if possible.
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*/
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if (pmn == &mp->mp_First ||
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(char *)pmn + ((MemNode *)pmn)->mr_Bytes != (char *)ptr
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) {
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((MemNode *)ptr)->mr_Next = NULL;
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((MemNode *)ptr)->mr_Bytes = bytes;
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*pmn = (MemNode *)ptr;
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mn = (MemNode *)ptr;
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} else {
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((MemNode *)pmn)->mr_Bytes += bytes;
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mn = (MemNode *)pmn;
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}
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}
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}
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/*
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* zextendPool() - extend memory pool to cover additional space.
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*
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* Note: the added memory starts out as allocated, you
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* must free it to make it available to the memory subsystem.
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*
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* Note: mp_Size may not reflect (mp_End - mp_Base) range
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* due to other parts of the system doing their own sbrk()
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* calls.
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*/
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void
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zextendPool(MemPool *mp, void *base, iaddr_t bytes)
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{
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if (mp->mp_Size == 0) {
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mp->mp_Base = base;
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mp->mp_Used = bytes;
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mp->mp_End = (char *)base + bytes;
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} else {
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void *pend = (char *)mp->mp_Base + mp->mp_Size;
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if (base < mp->mp_Base) {
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/* mp->mp_Size += (char *)mp->mp_Base - (char *)base; */
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mp->mp_Used += (char *)mp->mp_Base - (char *)base;
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mp->mp_Base = base;
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}
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base = (char *)base + bytes;
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if (base > pend) {
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/* mp->mp_Size += (char *)base - (char *)pend; */
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mp->mp_Used += (char *)base - (char *)pend;
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mp->mp_End = (char *)base;
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}
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}
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mp->mp_Size += bytes;
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}
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#ifdef ZALLOCDEBUG
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void
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zallocstats(MemPool *mp)
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{
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int abytes = 0;
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int hbytes = 0;
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int fcount = 0;
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MemNode *mn;
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printf("%d bytes reserved", (int) mp->mp_Size);
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mn = mp->mp_First;
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if ((void *)mn != (void *)mp->mp_Base) {
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abytes += (char *)mn - (char *)mp->mp_Base;
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}
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while (mn) {
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if ((char *)mn + mn->mr_Bytes != mp->mp_End) {
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hbytes += mn->mr_Bytes;
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++fcount;
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}
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if (mn->mr_Next)
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abytes += (char *)mn->mr_Next - ((char *)mn + mn->mr_Bytes);
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mn = mn->mr_Next;
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}
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printf(" %d bytes allocated\n%d fragments (%d bytes fragmented)\n",
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abytes,
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fcount,
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hbytes
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);
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}
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#endif
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