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/*
* Copyright (c) 2011 Ariane van der Steldt <ariane@stack.nl>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/hiballoc.h>
#include <sys/param.h>
#include <sys/tree.h>
#include <sys/types.h>
#include <sys/systm.h>
/*
* Hib alloc enforced alignment.
*/
#define HIB_ALIGN 8 /* bytes alignment */
/*
* sizeof builtin operation, but with alignment constraint.
*/
#define HIB_SIZEOF(_type) roundup(sizeof(_type), HIB_ALIGN)
struct hiballoc_entry
{
size_t hibe_use;
size_t hibe_space;
RB_ENTRY(hiballoc_entry) hibe_entry;
};
/*
* Compare hiballoc entries based on the address they manage.
*
* Since the address is fixed, relative to struct hiballoc_entry,
* we just compare the hiballoc_entry pointers.
*/
static __inline int
hibe_cmp(struct hiballoc_entry *l, struct hiballoc_entry *r)
{
return l < r ? -1 : (l > r);
}
RB_PROTOTYPE(hiballoc_addr, hiballoc_entry, hibe_entry, hibe_cmp)
/*
* Given a hiballoc entry, return the address it manages.
*/
static __inline void*
hib_entry_to_addr(struct hiballoc_entry *entry)
{
caddr_t addr;
addr = (caddr_t)entry;
addr += HIB_SIZEOF(struct hiballoc_entry);
return addr;
}
/*
* Given an address, find the hiballoc that corresponds.
*/
static __inline struct hiballoc_entry*
hib_addr_to_entry(void* addr_param)
{
caddr_t addr;
addr = (caddr_t)addr_param;
addr -= HIB_SIZEOF(struct hiballoc_entry);
return (struct hiballoc_entry*)addr;
}
RB_GENERATE(hiballoc_addr, hiballoc_entry, hibe_entry, hibe_cmp)
/*
* Allocate memory from the arena.
*
* Returns NULL if no memory is available.
*/
void*
hib_alloc(struct hiballoc_arena *arena, size_t alloc_sz)
{
struct hiballoc_entry *entry;
size_t find_sz;
/*
* Enforce alignment of HIB_ALIGN bytes.
*
* Note that, because the entry is put in front of the allocation,
* 0-byte allocations are guaranteed a unique address.
*/
alloc_sz = roundup(alloc_sz, HIB_ALIGN);
/*
* Find an entry with hibe_space >= find_sz.
*
* If the root node is not large enough, we switch to tree traversal.
* Because all entries are made at the bottom of the free space,
* traversal from the end has a slightly better chance of yielding
* a sufficiently large space.
*/
find_sz = alloc_sz + HIB_SIZEOF(struct hiballoc_entry);
entry = RB_ROOT(&arena->hib_addrs);
if (entry != NULL && entry->hibe_space < find_sz) {
RB_FOREACH_REVERSE(entry, hiballoc_addr, &arena->hib_addrs) {
if (entry->hibe_space >= find_sz)
break;
}
}
/*
* Insufficient or too fragmented memory.
*/
if (entry == NULL)
return NULL;
/*
* Create new entry in allocated space.
*/
struct hiballoc_entry *new_entry = (struct hiballoc_entry*)(
(caddr_t)hib_entry_to_addr(entry) + entry->hibe_use);
new_entry->hibe_space = entry->hibe_space - find_sz;
new_entry->hibe_use = alloc_sz;
/*
* Insert entry.
*/
if (RB_INSERT(hiballoc_addr, &arena->hib_addrs, new_entry) != NULL)
panic("hib_alloc: insert failure");
entry->hibe_space = 0;
/* Return address managed by entry. */
return hib_entry_to_addr(new_entry);
}
/*
* Free a pointer previously allocated from this arena.
*
* If addr is NULL, this will be silently accepted.
*/
void
hib_free(struct hiballoc_arena *arena, void *addr)
{
struct hiballoc_entry *entry, *prev;
if (addr == NULL)
return;
/*
* Derive entry from addr and check it is really in this arena.
*/
entry = hib_addr_to_entry(addr);
if (RB_FIND(hiballoc_addr, &arena->hib_addrs, entry) != entry)
panic("hib_free: freed item %p not in hib arena", addr);
/*
* Give the space in entry to its predecessor.
*
* If entry has no predecessor, change its used space into free space
* instead.
*/
prev = RB_PREV(hiballoc_addr, &arena->hib_addrs, entry);
if (prev != NULL &&
(void*)((caddr_t)prev + HIB_SIZEOF(struct hiballoc_entry) +
prev->hibe_use + prev->hibe_space) == entry) {
/* Merge entry. */
RB_REMOVE(hiballoc_addr, &arena->hib_addrs, entry);
prev->hibe_space += HIB_SIZEOF(struct hiballoc_entry) +
entry->hibe_use + entry->hibe_space;
} else {
/* Flip used memory to free space. */
entry->hibe_space += entry->hibe_use;
entry->hibe_use = 0;
}
}
/*
* Initialize hiballoc.
*
* The allocator will manage memmory at ptr, which is len bytes.
*/
int
hiballoc_init(struct hiballoc_arena *arena, void *p_ptr, size_t p_len)
{
struct hiballoc_entry *entry;
caddr_t ptr;
size_t len;
RB_INIT(&arena->hib_addrs);
/*
* Hib allocator enforces HIB_ALIGN alignment.
* Fixup ptr and len.
*/
ptr = (caddr_t)roundup((vaddr_t)p_ptr, HIB_ALIGN);
len = p_len - ((size_t)ptr - (size_t)p_ptr);
len &= ~((size_t)HIB_ALIGN - 1);
/*
* Insufficient memory to be able to allocate and also do bookkeeping.
*/
if (len <= HIB_SIZEOF(struct hiballoc_entry))
return ENOMEM;
/*
* Create entry describing space.
*/
entry = (struct hiballoc_entry*)ptr;
entry->hibe_use = 0;
entry->hibe_space = len - HIB_SIZEOF(struct hiballoc_entry);
RB_INSERT(hiballoc_addr, &arena->hib_addrs, entry);
return 0;
}
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