#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <stdint.h>
#include <errno.h>
#include <sys/mman.h>
#include "libc.h"
#include "atomic.h"
#include "pthread_impl.h"
uintptr_t __brk(uintptr_t);
void *__mmap(void *, size_t, int, int, int, off_t);
int __munmap(void *, size_t);
void *__mremap(void *, size_t, size_t, int, ...);
int __madvise(void *, size_t, int);
struct chunk {
size_t data[1];
struct chunk *next;
struct chunk *prev;
};
struct bin {
int lock[2];
struct chunk *head;
struct chunk *tail;
};
static struct {
uintptr_t brk;
size_t *heap;
uint64_t binmap;
struct bin bins[64];
int brk_lock[2];
int free_lock[2];
} mal;
#define SIZE_ALIGN (4*sizeof(size_t))
#define SIZE_MASK (-SIZE_ALIGN)
#define OVERHEAD (2*sizeof(size_t))
#define MMAP_THRESHOLD (0x1c00*SIZE_ALIGN)
#define DONTCARE 16
#define RECLAIM 163840
#define CHUNK_SIZE(c) ((c)->data[0] & SIZE_MASK)
#define CHUNK_PSIZE(c) ((c)->data[-1] & SIZE_MASK)
#define PREV_CHUNK(c) ((struct chunk *)((char *)(c) - CHUNK_PSIZE(c)))
#define NEXT_CHUNK(c) ((struct chunk *)((char *)(c) + CHUNK_SIZE(c)))
#define MEM_TO_CHUNK(p) (struct chunk *)((size_t *)p - 1)
#define CHUNK_TO_MEM(c) (void *)((c)->data+1)
#define BIN_TO_CHUNK(i) (MEM_TO_CHUNK(&mal.bins[i].head))
#define C_INUSE ((size_t)1)
#define C_FLAGS ((size_t)3)
#define C_SIZE SIZE_MASK
#define IS_MMAPPED(c) !((c)->data[0] & (C_INUSE))
/* Synchronization tools */
static void lock(volatile int *lk)
{
if (!libc.threads_minus_1) return;
while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1);
}
static void unlock(volatile int *lk)
{
if (!libc.threads_minus_1) return;
a_store(lk, 0);
if (lk[1]) __wake(lk, 1, 1);
}
static void lock_bin(int i)
{
if (libc.threads_minus_1)
lock(mal.bins[i].lock);
if (!mal.bins[i].head)
mal.bins[i].head = mal.bins[i].tail = BIN_TO_CHUNK(i);
}
static void unlock_bin(int i)
{
if (!libc.threads_minus_1) return;
unlock(mal.bins[i].lock);
}
static int first_set(uint64_t x)
{
#if 1
return a_ctz_64(x);
#else
static const char debruijn64[64] = {
0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
};
static const char debruijn32[32] = {
0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13,
31, 22, 28, 18, 26, 10, 7, 12, 21, 17, 9, 6, 16, 5, 15, 14
};
if (sizeof(long) < 8) {
uint32_t y = x;
if (!y) {
y = x>>32;
return 32 + debruijn32[(y&-y)*0x076be629 >> 27];
}
return debruijn32[(y&-y)*0x076be629 >> 27];
}
return debruijn64[(x&-x)*0x022fdd63cc95386dull >> 58];
#endif
}
static int bin_index(size_t x)
{
x = x / SIZE_ALIGN - 1;
if (x <= 32) return x;
if (x > 0x1c00) return 63;
return ((union { float v; uint32_t r; }){ x }.r>>21) - 496;
}
static int bin_index_up(size_t x)
{
x = x / SIZE_ALIGN - 1;
if (x <= 32) return x;
return ((union { float v; uint32_t r; }){ x }.r+0x1fffff>>21) - 496;
}
#if 0
void __dump_heap(int x)
{
struct chunk *c;
int i;
for (c = (void *)mal.heap; CHUNK_SIZE(c); c = NEXT_CHUNK(c))
fprintf(stderr, "base %p size %zu (%d) flags %d/%d\n",
c, CHUNK_SIZE(c), bin_index(CHUNK_SIZE(c)),
c->data[0] & 15,
NEXT_CHUNK(c)->data[-1] & 15);
for (i=0; i<64; i++) {
if (mal.bins[i].head != BIN_TO_CHUNK(i) && mal.bins[i].head) {
fprintf(stderr, "bin %d: %p\n", i, mal.bins[i].head);
if (!(mal.binmap & 1ULL<<i))
fprintf(stderr, "missing from binmap!\n");
} else if (mal.binmap & 1ULL<<i)
fprintf(stderr, "binmap wrongly contains %d!\n", i);
}
}
#endif
static struct chunk *expand_heap(size_t n)
{
struct chunk *w;
uintptr_t new;
lock(mal.brk_lock);
if (n > SIZE_MAX - mal.brk - 2*PAGE_SIZE) goto fail;
new = mal.brk + n + SIZE_ALIGN + PAGE_SIZE - 1 & -PAGE_SIZE;
n = new - mal.brk;
if (__brk(new) != new) goto fail;
w = MEM_TO_CHUNK(new);
w->data[-1] = n | C_INUSE;
w->data[0] = 0 | C_INUSE;
w = MEM_TO_CHUNK(mal.brk);
w->data[0] = n | C_INUSE;
mal.brk = new;
unlock(mal.brk_lock);
return w;
fail:
unlock(mal.brk_lock);
return 0;
}
static int init_malloc(size_t n)
{
static int init, waiters;
int state;
struct chunk *c;
if (init == 2) return 0;
while ((state=a_swap(&init, 1)) == 1)
__wait(&init, &waiters, 1, 1);
if (state) {
a_store(&init, 2);
return 0;
}
mal.brk = __brk(0) + 2*SIZE_ALIGN-1 & -SIZE_ALIGN;
c = expand_heap(n);
if (!c) {
a_store(&init, 0);
if (waiters) __wake(&init, 1, 1);
return -1;
}
mal.heap = (void *)c;
c->data[-1] = 0 | C_INUSE;
free(CHUNK_TO_MEM(c));
a_store(&init, 2);
if (waiters) __wake(&init, -1, 1);
return 1;
}
static int adjust_size(size_t *n)
{
/* Result of pointer difference must fit in ptrdiff_t. */
if (*n-1 > PTRDIFF_MAX - SIZE_ALIGN - PAGE_SIZE) {
if (*n) {
errno = ENOMEM;
return -1;
} else {
*n = SIZE_ALIGN;
return 0;
}
}
*n = (*n + OVERHEAD + SIZE_ALIGN - 1) & SIZE_MASK;
return 0;
}
static void unbin(struct chunk *c, int i)
{
if (c->prev == c->next)
a_and_64(&mal.binmap, ~(1ULL<<i));
c->prev->next = c->next;
c->next->prev = c->prev;
c->data[0] |= C_INUSE;
NEXT_CHUNK(c)->data[-1] |= C_INUSE;
}
static int alloc_fwd(struct chunk *c)
{
int i;
size_t k;
while (!((k=c->data[0]) & C_INUSE)) {
i = bin_index(k);
lock_bin(i);
if (c->data[0] == k) {
unbin(c, i);
unlock_bin(i);
return 1;
}
unlock_bin(i);
}
return 0;
}
static int alloc_rev(struct chunk *c)
{
int i;
size_t k;
while (!((k=c->data[-1]) & C_INUSE)) {
i = bin_index(k);
lock_bin(i);
if (c->data[-1] == k) {
unbin(PREV_CHUNK(c), i);
unlock_bin(i);
return 1;
}
unlock_bin(i);
}
return 0;
}
/* pretrim - trims a chunk _prior_ to removing it from its bin.
* Must be called with i as the ideal bin for size n, j the bin
* for the _free_ chunk self, and bin j locked. */
static int pretrim(struct chunk *self, size_t n, int i, int j)
{
size_t n1;
struct chunk *next, *split;
/* We cannot pretrim if it would require re-binning. */
if (j < 40) return 0;
if (j < i+3) {
if (j != 63) return 0;
n1 = CHUNK_SIZE(self);
if (n1-n <= MMAP_THRESHOLD) return 0;
} else {
n1 = CHUNK_SIZE(self);
}
if (bin_index(n1-n) != j) return 0;
next = NEXT_CHUNK(self);
split = (void *)((char *)self + n);
split->prev = self->prev;
split->next = self->next;
split->prev->next = split;
split->next->prev = split;
split->data[-1] = n | C_INUSE;
split->data[0] = n1-n;
next->data[-1] = n1-n;
self->data[0] = n | C_INUSE;
return 1;
}
static void trim(struct chunk *self, size_t n)
{
size_t n1 = CHUNK_SIZE(self);
struct chunk *next, *split;
if (n >= n1 - DONTCARE) return;
next = NEXT_CHUNK(self);
split = (void *)((char *)self + n);
split->data[-1] = n | C_INUSE;
split->data[0] = n1-n | C_INUSE;
next->data[-1] = n1-n | C_INUSE;
self->data[0] = n | C_INUSE;
free(CHUNK_TO_MEM(split));
}
void *malloc(size_t n)
{
struct chunk *c;
int i, j;
if (adjust_size(&n) < 0) return 0;
if (n > MMAP_THRESHOLD) {
size_t len = n + PAGE_SIZE - 1 & -PAGE_SIZE;
char *base = __mmap(0, len, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (base == (void *)-1) return 0;
c = (void *)(base + SIZE_ALIGN - sizeof(size_t));
c->data[0] = len - (SIZE_ALIGN - sizeof(size_t));
c->data[-1] = SIZE_ALIGN - sizeof(size_t);
return CHUNK_TO_MEM(c);
}
i = bin_index_up(n);
for (;;) {
uint64_t mask = mal.binmap & -(1ULL<<i);
if (!mask) {
if (init_malloc(n) > 0) continue;
c = expand_heap(n);
if (!c) return 0;
if (alloc_rev(c)) {
struct chunk *x = c;
c = PREV_CHUNK(c);
NEXT_CHUNK(x)->data[-1] = c->data[0] =
x->data[0] + CHUNK_SIZE(c);
}
break;
}
j = first_set(mask);
lock_bin(j);
c = mal.bins[j].head;
if (c != BIN_TO_CHUNK(j) && j == bin_index(c->data[0])) {
if (!pretrim(c, n, i, j)) unbin(c, j);
unlock_bin(j);
break;
}
unlock_bin(j);
}
/* Now patch up in case we over-allocated */
trim(c, n);
return CHUNK_TO_MEM(c);
}
void *realloc(void *p, size_t n)
{
struct chunk *self, *next;
size_t n0, n1;
void *new;
if (!p) return malloc(n);
if (adjust_size(&n) < 0) return 0;
self = MEM_TO_CHUNK(p);
n1 = n0 = CHUNK_SIZE(self);
if (IS_MMAPPED(self)) {
size_t extra = self->data[-1];
char *base = (char *)self - extra;
size_t oldlen = n0 + extra;
size_t newlen = n + extra;
/* Crash on realloc of freed chunk */
if ((uintptr_t)base < mal.brk) *(char *)0=0;
if (newlen < PAGE_SIZE && (new = malloc(n))) {
memcpy(new, p, n-OVERHEAD);
free(p);
return new;
}
newlen = (newlen + PAGE_SIZE-1) & -PAGE_SIZE;
if (oldlen == newlen) return p;
base = __mremap(base, oldlen, newlen, MREMAP_MAYMOVE);
if (base == (void *)-1)
return newlen < oldlen ? p : 0;
self = (void *)(base + extra);
self->data[0] = newlen - extra;
return CHUNK_TO_MEM(self);
}
next = NEXT_CHUNK(self);
/* Merge adjacent chunks if we need more space. This is not
* a waste of time even if we fail to get enough space, because our
* subsequent call to free would otherwise have to do the merge. */
if (n > n1 && alloc_fwd(next)) {
n1 += CHUNK_SIZE(next);
next = NEXT_CHUNK(next);
}
/* FIXME: find what's wrong here and reenable it..? */
if (0 && n > n1 && alloc_rev(self)) {
self = PREV_CHUNK(self);
n1 += CHUNK_SIZE(self);
}
self->data[0] = n1 | C_INUSE;
next->data[-1] = n1 | C_INUSE;
/* If we got enough space, split off the excess and return */
if (n <= n1) {
//memmove(CHUNK_TO_MEM(self), p, n0-OVERHEAD);
trim(self, n);
return CHUNK_TO_MEM(self);
}
/* As a last resort, allocate a new chunk and copy to it. */
new = malloc(n-OVERHEAD);
if (!new) return 0;
memcpy(new, p, n0-OVERHEAD);
free(CHUNK_TO_MEM(self));
return new;
}
void free(void *p)
{
struct chunk *self = MEM_TO_CHUNK(p);
struct chunk *next;
size_t final_size, new_size, size;
int reclaim=0;
int i;
if (!p) return;
if (IS_MMAPPED(self)) {
size_t extra = self->data[-1];
char *base = (char *)self - extra;
size_t len = CHUNK_SIZE(self) + extra;
/* Crash on double free */
if ((uintptr_t)base < mal.brk) *(char *)0=0;
__munmap(base, len);
return;
}
final_size = new_size = CHUNK_SIZE(self);
next = NEXT_CHUNK(self);
for (;;) {
/* Replace middle of large chunks with fresh zero pages */
if (reclaim && (self->data[-1] & next->data[0] & C_INUSE)) {
uintptr_t a = (uintptr_t)self + SIZE_ALIGN+PAGE_SIZE-1 & -PAGE_SIZE;
uintptr_t b = (uintptr_t)next - SIZE_ALIGN & -PAGE_SIZE;
#if 1
__madvise((void *)a, b-a, MADV_DONTNEED);
#else
__mmap((void *)a, b-a, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0);
#endif
}
if (self->data[-1] & next->data[0] & C_INUSE) {
self->data[0] = final_size | C_INUSE;
next->data[-1] = final_size | C_INUSE;
i = bin_index(final_size);
lock_bin(i);
lock(mal.free_lock);
if (self->data[-1] & next->data[0] & C_INUSE)
break;
unlock(mal.free_lock);
unlock_bin(i);
}
if (alloc_rev(self)) {
self = PREV_CHUNK(self);
size = CHUNK_SIZE(self);
final_size += size;
if (new_size+size > RECLAIM && (new_size+size^size) > size)
reclaim = 1;
}
if (alloc_fwd(next)) {
size = CHUNK_SIZE(next);
final_size += size;
if (new_size+size > RECLAIM && (new_size+size^size) > size)
reclaim = 1;
next = NEXT_CHUNK(next);
}
}
self->data[0] = final_size;
next->data[-1] = final_size;
unlock(mal.free_lock);
self->next = BIN_TO_CHUNK(i);
self->prev = mal.bins[i].tail;
self->next->prev = self;
self->prev->next = self;
if (!(mal.binmap & 1ULL<<i))
a_or_64(&mal.binmap, 1ULL<<i);
unlock_bin(i);
}
