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/*
* Copyright © 2018 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <stdlib.h>
#include "util/u_math.h"
#include "util/vma.h"
struct util_vma_hole {
struct list_head link;
uint64_t offset;
uint64_t size;
};
#define util_vma_foreach_hole(_hole, _heap) \
list_for_each_entry(struct util_vma_hole, _hole, &(_heap)->holes, link)
#define util_vma_foreach_hole_safe(_hole, _heap) \
list_for_each_entry_safe(struct util_vma_hole, _hole, &(_heap)->holes, link)
void
util_vma_heap_init(struct util_vma_heap *heap,
uint64_t start, uint64_t size)
{
list_inithead(&heap->holes);
util_vma_heap_free(heap, start, size);
}
void
util_vma_heap_finish(struct util_vma_heap *heap)
{
util_vma_foreach_hole_safe(hole, heap)
free(hole);
}
#ifndef NDEBUG
static void
util_vma_heap_validate(struct util_vma_heap *heap)
{
uint64_t prev_offset = 0;
util_vma_foreach_hole(hole, heap) {
assert(hole->offset > 0);
assert(hole->size > 0);
if (&hole->link == heap->holes.next) {
/* This must be the top-most hole. Assert that, if it overflows, it
* overflows to 0, i.e. 2^64.
*/
assert(hole->size + hole->offset == 0 ||
hole->size + hole->offset > hole->offset);
} else {
/* This is not the top-most hole so it must not overflow and, in
* fact, must be strictly lower than the top-most hole. If
* hole->size + hole->offset == prev_offset, then we failed to join
* holes during a util_vma_heap_free.
*/
assert(hole->size + hole->offset > hole->offset &&
hole->size + hole->offset < prev_offset);
}
prev_offset = hole->offset;
}
}
#else
#define util_vma_heap_validate(heap)
#endif
uint64_t
util_vma_heap_alloc(struct util_vma_heap *heap,
uint64_t size, uint64_t alignment)
{
/* The caller is expected to reject zero-size allocations */
assert(size > 0);
assert(alignment > 0);
util_vma_heap_validate(heap);
util_vma_foreach_hole_safe(hole, heap) {
if (size > hole->size)
continue;
/* Compute the offset as the highest address where a chunk of the given
* size can be without going over the top of the hole.
*
* This calculation is known to not overflow because we know that
* hole->size + hole->offset can only overflow to 0 and size > 0.
*/
uint64_t offset = (hole->size - size) + hole->offset;
/* Align the offset. We align down and not up because we are allocating
* from the top of the hole and not the bottom.
*/
offset = (offset / alignment) * alignment;
if (offset < hole->offset)
continue;
if (offset == hole->offset && size == hole->size) {
/* Just get rid of the hole. */
list_del(&hole->link);
free(hole);
util_vma_heap_validate(heap);
return offset;
}
assert(offset - hole->offset <= hole->size - size);
uint64_t waste = (hole->size - size) - (offset - hole->offset);
if (waste == 0) {
/* We allocated at the top. Shrink the hole down. */
hole->size -= size;
util_vma_heap_validate(heap);
return offset;
}
if (offset == hole->offset) {
/* We allocated at the bottom. Shrink the hole up. */
hole->offset += size;
hole->size -= size;
util_vma_heap_validate(heap);
return offset;
}
/* We allocated in the middle. We need to split the old hole into two
* holes, one high and one low.
*/
struct util_vma_hole *high_hole = calloc(1, sizeof(*hole));
high_hole->offset = offset + size;
high_hole->size = waste;
/* Adjust the hole to be the amount of space left at he bottom of the
* original hole.
*/
hole->size = offset - hole->offset;
/* Place the new hole before the old hole so that the list is in order
* from high to low.
*/
list_addtail(&high_hole->link, &hole->link);
util_vma_heap_validate(heap);
return offset;
}
/* Failed to allocate */
return 0;
}
void
util_vma_heap_free(struct util_vma_heap *heap,
uint64_t offset, uint64_t size)
{
/* An offset of 0 is reserved for allocation failure. It is not a valid
* address and cannot be freed.
*/
assert(offset > 0);
/* Freeing something with a size of 0 is also not valid. */
assert(size > 0);
/* It's possible for offset + size to wrap around if we touch the top of
* the 64-bit address space, but we cannot go any higher than 2^64.
*/
assert(offset + size == 0 || offset + size > offset);
util_vma_heap_validate(heap);
/* Find immediately higher and lower holes if they exist. */
struct util_vma_hole *high_hole = NULL, *low_hole = NULL;
util_vma_foreach_hole(hole, heap) {
if (hole->offset <= offset) {
low_hole = hole;
break;
}
high_hole = hole;
}
if (high_hole)
assert(offset + size <= high_hole->offset);
bool high_adjacent = high_hole && offset + size == high_hole->offset;
if (low_hole) {
assert(low_hole->offset + low_hole->size > low_hole->offset);
assert(low_hole->offset + low_hole->size <= offset);
}
bool low_adjacent = low_hole && low_hole->offset + low_hole->size == offset;
if (low_adjacent && high_adjacent) {
/* Merge the two holes */
low_hole->size += size + high_hole->size;
list_del(&high_hole->link);
free(high_hole);
} else if (low_adjacent) {
/* Merge into the low hole */
low_hole->size += size;
} else if (high_adjacent) {
/* Merge into the high hole */
high_hole->offset = offset;
high_hole->size += size;
} else {
/* Neither hole is adjacent; make a new one */
struct util_vma_hole *hole = calloc(1, sizeof(*hole));
hole->offset = offset;
hole->size = size;
/* Add it after the high hole so we maintain high-to-low ordering */
if (high_hole)
list_add(&hole->link, &high_hole->link);
else
list_add(&hole->link, &heap->holes);
}
util_vma_heap_validate(heap);
}
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