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Unified Diff: fusl/src/malloc/malloc.c

Issue 1573973002: Add a "fork" of musl as //fusl. (Closed) Base URL: https://github.com/domokit/mojo.git@master
Patch Set: Created 4 years, 11 months ago
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Index: fusl/src/malloc/malloc.c
diff --git a/fusl/src/malloc/malloc.c b/fusl/src/malloc/malloc.c
new file mode 100644
index 0000000000000000000000000000000000000000..b90636cc67fda06dac201526d43a42f5e040971c
--- /dev/null
+++ b/fusl/src/malloc/malloc.c
@@ -0,0 +1,521 @@
+#define _GNU_SOURCE
+#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"
+
+#if defined(__GNUC__) && defined(__PIC__)
+#define inline inline __attribute__((always_inline))
+#endif
+
+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 psize, csize;
+ struct chunk *next, *prev;
+};
+
+struct bin {
+ volatile int lock[2];
+ struct chunk *head;
+ struct chunk *tail;
+};
+
+static struct {
+ volatile uint64_t binmap;
+ struct bin bins[64];
+ volatile 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)->csize & -2)
+#define CHUNK_PSIZE(c) ((c)->psize & -2)
+#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 *)((char *)(p) - OVERHEAD)
+#define CHUNK_TO_MEM(c) (void *)((char *)(c) + OVERHEAD)
+#define BIN_TO_CHUNK(i) (MEM_TO_CHUNK(&mal.bins[i].head))
+
+#define C_INUSE ((size_t)1)
+
+#define IS_MMAPPED(c) !((c)->csize & (C_INUSE))
+
+
+/* Synchronization tools */
+
+static inline void lock(volatile int *lk)
+{
+ if (libc.threads_minus_1)
+ while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1);
+}
+
+static inline void unlock(volatile int *lk)
+{
+ if (lk[0]) {
+ a_store(lk, 0);
+ if (lk[1]) __wake(lk, 1, 1);
+ }
+}
+
+static inline void lock_bin(int i)
+{
+ lock(mal.bins[i].lock);
+ if (!mal.bins[i].head)
+ mal.bins[i].head = mal.bins[i].tail = BIN_TO_CHUNK(i);
+}
+
+static inline void unlock_bin(int i)
+{
+ 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; }){(int)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; }){(int)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->csize & 15,
+ NEXT_CHUNK(c)->psize & 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
+
+void *__expand_heap(size_t *);
+
+static struct chunk *expand_heap(size_t n)
+{
+ static int heap_lock[2];
+ static void *end;
+ void *p;
+ struct chunk *w;
+
+ /* The argument n already accounts for the caller's chunk
+ * overhead needs, but if the heap can't be extended in-place,
+ * we need room for an extra zero-sized sentinel chunk. */
+ n += SIZE_ALIGN;
+
+ lock(heap_lock);
+
+ p = __expand_heap(&n);
+ if (!p) {
+ unlock(heap_lock);
+ return 0;
+ }
+
+ /* If not just expanding existing space, we need to make a
+ * new sentinel chunk below the allocated space. */
+ if (p != end) {
+ /* Valid/safe because of the prologue increment. */
+ n -= SIZE_ALIGN;
+ p = (char *)p + SIZE_ALIGN;
+ w = MEM_TO_CHUNK(p);
+ w->psize = 0 | C_INUSE;
+ }
+
+ /* Record new heap end and fill in footer. */
+ end = (char *)p + n;
+ w = MEM_TO_CHUNK(end);
+ w->psize = n | C_INUSE;
+ w->csize = 0 | C_INUSE;
+
+ /* Fill in header, which may be new or may be replacing a
+ * zero-size sentinel header at the old end-of-heap. */
+ w = MEM_TO_CHUNK(p);
+ w->csize = n | C_INUSE;
+
+ unlock(heap_lock);
+
+ return w;
+}
+
+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->csize |= C_INUSE;
+ NEXT_CHUNK(c)->psize |= C_INUSE;
+}
+
+static int alloc_fwd(struct chunk *c)
+{
+ int i;
+ size_t k;
+ while (!((k=c->csize) & C_INUSE)) {
+ i = bin_index(k);
+ lock_bin(i);
+ if (c->csize == 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->psize) & C_INUSE)) {
+ i = bin_index(k);
+ lock_bin(i);
+ if (c->psize == 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->psize = n | C_INUSE;
+ split->csize = n1-n;
+ next->psize = n1-n;
+ self->csize = 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->psize = n | C_INUSE;
+ split->csize = n1-n | C_INUSE;
+ next->psize = n1-n | C_INUSE;
+ self->csize = 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 + OVERHEAD + 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 - OVERHEAD);
+ c->csize = len - (SIZE_ALIGN - OVERHEAD);
+ c->psize = SIZE_ALIGN - OVERHEAD;
+ return CHUNK_TO_MEM(c);
+ }
+
+ i = bin_index_up(n);
+ for (;;) {
+ uint64_t mask = mal.binmap & -(1ULL<<i);
+ if (!mask) {
+ c = expand_heap(n);
+ if (!c) return 0;
+ if (alloc_rev(c)) {
+ struct chunk *x = c;
+ c = PREV_CHUNK(c);
+ NEXT_CHUNK(x)->psize = c->csize =
+ x->csize + CHUNK_SIZE(c);
+ }
+ break;
+ }
+ j = first_set(mask);
+ lock_bin(j);
+ c = mal.bins[j].head;
+ if (c != BIN_TO_CHUNK(j)) {
+ 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 *__malloc0(size_t n)
+{
+ void *p = malloc(n);
+ if (p && !IS_MMAPPED(MEM_TO_CHUNK(p))) {
+ size_t *z;
+ n = (n + sizeof *z - 1)/sizeof *z;
+ for (z=p; n; n--, z++) if (*z) *z=0;
+ }
+ return p;
+}
+
+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->psize;
+ char *base = (char *)self - extra;
+ size_t oldlen = n0 + extra;
+ size_t newlen = n + extra;
+ /* Crash on realloc of freed chunk */
+ if (extra & 1) a_crash();
+ 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->csize = newlen - extra;
+ return CHUNK_TO_MEM(self);
+ }
+
+ next = NEXT_CHUNK(self);
+
+ /* Crash on corrupted footer (likely from buffer overflow) */
+ if (next->psize != self->csize) a_crash();
+
+ /* 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->csize = n1 | C_INUSE;
+ next->psize = 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->psize;
+ char *base = (char *)self - extra;
+ size_t len = CHUNK_SIZE(self) + extra;
+ /* Crash on double free */
+ if (extra & 1) a_crash();
+ __munmap(base, len);
+ return;
+ }
+
+ final_size = new_size = CHUNK_SIZE(self);
+ next = NEXT_CHUNK(self);
+
+ /* Crash on corrupted footer (likely from buffer overflow) */
+ if (next->psize != self->csize) a_crash();
+
+ for (;;) {
+ if (self->psize & next->csize & C_INUSE) {
+ self->csize = final_size | C_INUSE;
+ next->psize = final_size | C_INUSE;
+ i = bin_index(final_size);
+ lock_bin(i);
+ lock(mal.free_lock);
+ if (self->psize & next->csize & 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);
+ }
+ }
+
+ if (!(mal.binmap & 1ULL<<i))
+ a_or_64(&mal.binmap, 1ULL<<i);
+
+ self->csize = final_size;
+ next->psize = 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;
+
+ /* Replace middle of large chunks with fresh zero pages */
+ if (reclaim) {
+ 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
+ }
+
+ unlock_bin(i);
+}
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