eduOS/mm/malloc.c

223 lines
5.8 KiB
C

/*
* Copyright (c) 2014, Steffen Vogel, RWTH Aachen University
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @author Steffen Vogel <steffen.vogel@rwth-aachen.de>
*/
#include <eduos/stdio.h>
#include <eduos/malloc.h>
#include <eduos/spinlock.h>
#include <eduos/memory.h>
#include <asm/page.h>
/// A linked list for each binary size exponent
static buddy_t* buddy_lists[BUDDY_LISTS] = { [0 ... BUDDY_LISTS-1] = NULL };
/// Lock for the buddy lists
static spinlock_t buddy_lock = SPINLOCK_INIT;
/** @brief Check if larger free buddies are available */
static inline int buddy_large_avail(uint8_t exp)
{
while (exp<BUDDY_MAX && !buddy_lists[exp-BUDDY_MIN])
exp++;
return exp != BUDDY_MAX;
}
/** @brief Calculate the required buddy size */
static inline int buddy_exp(size_t sz)
{
int exp;
for (exp=0; sz>(1<<exp); exp++);
if (exp > BUDDY_MAX)
exp = 0;
if (exp < BUDDY_MIN)
exp = BUDDY_MIN;
return exp;
}
/** @brief Get a free buddy by potentially splitting a larger one */
static buddy_t* buddy_get(int exp)
{
spinlock_lock(&buddy_lock);
buddy_t** list = &buddy_lists[exp-BUDDY_MIN];
buddy_t* buddy = *list;
buddy_t* split;
if (buddy)
// there is already a free buddy =>
// we remove it from the list
*list = buddy->next;
else if (exp >= BUDDY_ALLOC && !buddy_large_avail(exp))
// theres no free buddy larger than exp =>
// we can allocate new memory
buddy = (buddy_t*) palloc(1<<exp, 0);
else {
// we recursivly request a larger buddy...
buddy = buddy_get(exp+1);
if (BUILTIN_EXPECT(!buddy, 0))
goto out;
// ... and split it, by putting the second half back to the list
split = (buddy_t*) ((size_t) buddy + (1<<exp));
split->next = *list;
*list = split;
}
out:
spinlock_unlock(&buddy_lock);
return buddy;
}
/** @brief Put a buddy back to its free list
*
* TODO: merge adjacent buddies (memory compaction)
*/
static void buddy_put(buddy_t* buddy)
{
spinlock_lock(&buddy_lock);
buddy_t** list = &buddy_lists[buddy->prefix.exponent-BUDDY_MIN];
buddy->next = *list;
*list = buddy;
spinlock_unlock(&buddy_lock);
}
void buddy_dump(void)
{
size_t free = 0;
int i;
for (i=0; i<BUDDY_LISTS; i++) {
buddy_t* buddy;
int exp = i+BUDDY_MIN;
if (buddy_lists[i])
kprintf("buddy_list[%u] (exp=%u, size=%lu bytes):\n", i, exp, 1<<exp);
for (buddy=buddy_lists[i]; buddy; buddy=buddy->next) {
kprintf(" %p -> %p \n", buddy, buddy->next);
free += 1<<exp;
}
}
kprintf("free buddies: %lu bytes\n", free);
}
void* palloc(size_t sz, uint32_t flags)
{
size_t phyaddr, viraddr;
uint32_t npages = PAGE_FLOOR(sz) >> PAGE_BITS;
int err;
//kprintf("palloc(%lu) (%lu pages)\n", sz, npages);
// get free virtual address space
viraddr = vma_alloc(npages*PAGE_SIZE, VMA_HEAP);
if (BUILTIN_EXPECT(!viraddr, 0))
return NULL;
// get continous physical pages
phyaddr = get_pages(npages);
if (BUILTIN_EXPECT(!phyaddr, 0)) {
vma_free(viraddr, viraddr+npages*PAGE_SIZE);
return NULL;
}
// map physical pages to VMA
err = page_map(viraddr, phyaddr, npages, PG_RW|PG_GLOBAL);
if (BUILTIN_EXPECT(err, 0)) {
vma_free(viraddr, viraddr+npages*PAGE_SIZE);
put_pages(phyaddr, npages);
return NULL;
}
return (void*) viraddr;
}
void pfree(void* addr, size_t sz)
{
if (BUILTIN_EXPECT(!addr || !sz, 0))
return;
size_t i;
size_t phyaddr;
size_t viraddr = (size_t) addr & PAGE_MASK;
uint32_t npages = PAGE_FLOOR(sz) >> PAGE_BITS;
// memory is probably not continuously mapped! (userspace heap)
for (i=0; i<npages; i++) {
phyaddr = virt_to_phys(viraddr+i*PAGE_SIZE);
put_page(phyaddr);
}
page_unmap(viraddr, npages);
vma_free(viraddr, viraddr+npages*PAGE_SIZE);
}
void* kmalloc(size_t sz)
{
if (BUILTIN_EXPECT(!sz, 0))
return NULL;
// add space for the prefix
sz += sizeof(buddy_t);
int exp = buddy_exp(sz);
if (BUILTIN_EXPECT(!exp, 0))
return NULL;
buddy_t* buddy = buddy_get(exp);
if (BUILTIN_EXPECT(!buddy, 0))
return NULL;
// setup buddy prefix
buddy->prefix.magic = BUDDY_MAGIC;
buddy->prefix.exponent = exp;
//kprintf("kmalloc(%lu) = %p\n", sz, buddy+1);
// pointer arithmetic: we hide the prefix
return buddy+1;
}
void kfree(void *addr)
{
if (BUILTIN_EXPECT(!addr, 0))
return;
//kprintf("kfree(%lu)\n", addr);
buddy_t* buddy = (buddy_t*) addr - 1; // get prefix
// check magic
if (BUILTIN_EXPECT(buddy->prefix.magic != BUDDY_MAGIC, 0))
return;
buddy_put(buddy);
}