10 #include "pthread_impl.h"
11 #include "malloc_impl.h"
13 #if defined(__GNUC__) && defined(__PIC__)
14 #define inline inline __attribute__((always_inline))
18 volatile uint64_t binmap
;
20 volatile int split_merge_lock
[2];
23 int __malloc_replaced
;
25 /* Synchronization tools */
27 static inline void lock(volatile int *lk
)
29 int need_locks
= libc
.need_locks
;
31 while(a_swap(lk
, 1)) __wait(lk
, lk
+1, 1, 1);
32 if (need_locks
< 0) libc
.need_locks
= 0;
36 static inline void unlock(volatile int *lk
)
40 if (lk
[1]) __wake(lk
, 1, 1);
44 static inline void lock_bin(int i
)
46 lock(mal
.bins
[i
].lock
);
47 if (!mal
.bins
[i
].head
)
48 mal
.bins
[i
].head
= mal
.bins
[i
].tail
= BIN_TO_CHUNK(i
);
51 static inline void unlock_bin(int i
)
53 unlock(mal
.bins
[i
].lock
);
56 static int first_set(uint64_t x
)
61 static const char debruijn64
[64] = {
62 0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
63 62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
64 63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
65 51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
67 static const char debruijn32
[32] = {
68 0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13,
69 31, 22, 28, 18, 26, 10, 7, 12, 21, 17, 9, 6, 16, 5, 15, 14
71 if (sizeof(long) < 8) {
75 return 32 + debruijn32
[(y
&-y
)*0x076be629 >> 27];
77 return debruijn32
[(y
&-y
)*0x076be629 >> 27];
79 return debruijn64
[(x
&-x
)*0x022fdd63cc95386dull
>> 58];
83 static const unsigned char bin_tab
[60] = {
84 32,33,34,35,36,36,37,37,38,38,39,39,
85 40,40,40,40,41,41,41,41,42,42,42,42,43,43,43,43,
86 44,44,44,44,44,44,44,44,45,45,45,45,45,45,45,45,
87 46,46,46,46,46,46,46,46,47,47,47,47,47,47,47,47,
90 static int bin_index(size_t x
)
92 x
= x
/ SIZE_ALIGN
- 1;
93 if (x
<= 32) return x
;
94 if (x
< 512) return bin_tab
[x
/8-4];
95 if (x
> 0x1c00) return 63;
96 return bin_tab
[x
/128-4] + 16;
99 static int bin_index_up(size_t x
)
101 x
= x
/ SIZE_ALIGN
- 1;
102 if (x
<= 32) return x
;
104 if (x
< 512) return bin_tab
[x
/8-4] + 1;
105 return bin_tab
[x
/128-4] + 17;
109 void __dump_heap(int x
)
113 for (c
= (void *)mal
.heap
; CHUNK_SIZE(c
); c
= NEXT_CHUNK(c
))
114 fprintf(stderr
, "base %p size %zu (%d) flags %d/%d\n",
115 c
, CHUNK_SIZE(c
), bin_index(CHUNK_SIZE(c
)),
117 NEXT_CHUNK(c
)->psize
& 15);
118 for (i
=0; i
<64; i
++) {
119 if (mal
.bins
[i
].head
!= BIN_TO_CHUNK(i
) && mal
.bins
[i
].head
) {
120 fprintf(stderr
, "bin %d: %p\n", i
, mal
.bins
[i
].head
);
121 if (!(mal
.binmap
& 1ULL<<i
))
122 fprintf(stderr
, "missing from binmap!\n");
123 } else if (mal
.binmap
& 1ULL<<i
)
124 fprintf(stderr
, "binmap wrongly contains %d!\n", i
);
129 /* This function returns true if the interval [old,new]
130 * intersects the 'len'-sized interval below &libc.auxv
131 * (interpreted as the main-thread stack) or below &b
132 * (the current stack). It is used to defend against
133 * buggy brk implementations that can cross the stack. */
135 static int traverses_stack_p(uintptr_t old
, uintptr_t new)
137 const uintptr_t len
= 8<<20;
140 b
= (uintptr_t)libc
.auxv
;
141 a
= b
> len
? b
-len
: 0;
142 if (new>a
&& old
<b
) return 1;
145 a
= b
> len
? b
-len
: 0;
146 if (new>a
&& old
<b
) return 1;
151 /* Expand the heap in-place if brk can be used, or otherwise via mmap,
152 * using an exponential lower bound on growth by mmap to make
153 * fragmentation asymptotically irrelevant. The size argument is both
154 * an input and an output, since the caller needs to know the size
155 * allocated, which will be larger than requested due to page alignment
156 * and mmap minimum size rules. The caller is responsible for locking
157 * to prevent concurrent calls. */
159 static void *__expand_heap(size_t *pn
)
161 static uintptr_t brk
;
162 static unsigned mmap_step
;
165 if (n
> SIZE_MAX
/2 - PAGE_SIZE
) {
169 n
+= -n
& PAGE_SIZE
-1;
172 brk
= __syscall(SYS_brk
, 0);
173 brk
+= -brk
& PAGE_SIZE
-1;
176 if (n
< SIZE_MAX
-brk
&& !traverses_stack_p(brk
, brk
+n
)
177 && __syscall(SYS_brk
, brk
+n
)==brk
+n
) {
180 return (void *)(brk
-n
);
183 size_t min
= (size_t)PAGE_SIZE
<< mmap_step
/2;
184 if (n
< min
) n
= min
;
185 void *area
= __mmap(0, n
, PROT_READ
|PROT_WRITE
,
186 MAP_PRIVATE
|MAP_ANONYMOUS
, -1, 0);
187 if (area
== MAP_FAILED
) return 0;
193 static struct chunk
*expand_heap(size_t n
)
199 /* The argument n already accounts for the caller's chunk
200 * overhead needs, but if the heap can't be extended in-place,
201 * we need room for an extra zero-sized sentinel chunk. */
204 p
= __expand_heap(&n
);
207 /* If not just expanding existing space, we need to make a
208 * new sentinel chunk below the allocated space. */
210 /* Valid/safe because of the prologue increment. */
212 p
= (char *)p
+ SIZE_ALIGN
;
214 w
->psize
= 0 | C_INUSE
;
217 /* Record new heap end and fill in footer. */
219 w
= MEM_TO_CHUNK(end
);
220 w
->psize
= n
| C_INUSE
;
221 w
->csize
= 0 | C_INUSE
;
223 /* Fill in header, which may be new or may be replacing a
224 * zero-size sentinel header at the old end-of-heap. */
226 w
->csize
= n
| C_INUSE
;
231 static int adjust_size(size_t *n
)
233 /* Result of pointer difference must fit in ptrdiff_t. */
234 if (*n
-1 > PTRDIFF_MAX
- SIZE_ALIGN
- PAGE_SIZE
) {
243 *n
= (*n
+ OVERHEAD
+ SIZE_ALIGN
- 1) & SIZE_MASK
;
247 static void unbin(struct chunk
*c
, int i
)
249 if (c
->prev
== c
->next
)
250 a_and_64(&mal
.binmap
, ~(1ULL<<i
));
251 c
->prev
->next
= c
->next
;
252 c
->next
->prev
= c
->prev
;
254 NEXT_CHUNK(c
)->psize
|= C_INUSE
;
257 static void bin_chunk(struct chunk
*self
, int i
)
259 self
->next
= BIN_TO_CHUNK(i
);
260 self
->prev
= mal
.bins
[i
].tail
;
261 self
->next
->prev
= self
;
262 self
->prev
->next
= self
;
263 if (self
->prev
== BIN_TO_CHUNK(i
))
264 a_or_64(&mal
.binmap
, 1ULL<<i
);
267 static void trim(struct chunk
*self
, size_t n
)
269 size_t n1
= CHUNK_SIZE(self
);
270 struct chunk
*next
, *split
;
272 if (n
>= n1
- DONTCARE
) return;
274 next
= NEXT_CHUNK(self
);
275 split
= (void *)((char *)self
+ n
);
277 split
->psize
= n
| C_INUSE
;
280 self
->csize
= n
| C_INUSE
;
282 int i
= bin_index(n1
-n
);
290 void *malloc(size_t n
)
296 if (adjust_size(&n
) < 0) return 0;
298 if (n
> MMAP_THRESHOLD
) {
299 size_t len
= n
+ OVERHEAD
+ PAGE_SIZE
- 1 & -PAGE_SIZE
;
300 char *base
= __mmap(0, len
, PROT_READ
|PROT_WRITE
,
301 MAP_PRIVATE
|MAP_ANONYMOUS
, -1, 0);
302 if (base
== (void *)-1) return 0;
303 c
= (void *)(base
+ SIZE_ALIGN
- OVERHEAD
);
304 c
->csize
= len
- (SIZE_ALIGN
- OVERHEAD
);
305 c
->psize
= SIZE_ALIGN
- OVERHEAD
;
306 return CHUNK_TO_MEM(c
);
310 if (i
<63 && (mal
.binmap
& (1ULL<<i
))) {
312 c
= mal
.bins
[i
].head
;
313 if (c
!= BIN_TO_CHUNK(i
) && CHUNK_SIZE(c
)-n
<= DONTCARE
) {
316 return CHUNK_TO_MEM(c
);
320 lock(mal
.split_merge_lock
);
321 for (mask
= mal
.binmap
& -(1ULL<<i
); mask
; mask
-= (mask
&-mask
)) {
324 c
= mal
.bins
[j
].head
;
325 if (c
!= BIN_TO_CHUNK(j
)) {
335 unlock(mal
.split_merge_lock
);
340 unlock(mal
.split_merge_lock
);
341 return CHUNK_TO_MEM(c
);
344 static size_t mal0_clear(char *p
, size_t pagesz
, size_t n
)
347 typedef uint64_t __attribute__((__may_alias__
)) T
;
349 typedef unsigned char T
;
352 size_t i
= (uintptr_t)pp
& (pagesz
- 1);
354 pp
= memset(pp
- i
, 0, i
);
355 if (pp
- p
< pagesz
) return pp
- p
;
356 for (i
= pagesz
; i
; i
-= 2*sizeof(T
), pp
-= 2*sizeof(T
))
357 if (((T
*)pp
)[-1] | ((T
*)pp
)[-2])
362 void *calloc(size_t m
, size_t n
)
364 if (n
&& m
> (size_t)-1/n
) {
371 if (!__malloc_replaced
) {
372 if (IS_MMAPPED(MEM_TO_CHUNK(p
)))
375 n
= mal0_clear(p
, PAGE_SIZE
, n
);
377 return memset(p
, 0, n
);
380 void *realloc(void *p
, size_t n
)
382 struct chunk
*self
, *next
;
386 if (!p
) return malloc(n
);
388 if (adjust_size(&n
) < 0) return 0;
390 self
= MEM_TO_CHUNK(p
);
391 n1
= n0
= CHUNK_SIZE(self
);
393 if (n
<=n0
&& n0
-n
<=DONTCARE
) return p
;
395 if (IS_MMAPPED(self
)) {
396 size_t extra
= self
->psize
;
397 char *base
= (char *)self
- extra
;
398 size_t oldlen
= n0
+ extra
;
399 size_t newlen
= n
+ extra
;
400 /* Crash on realloc of freed chunk */
401 if (extra
& 1) a_crash();
402 if (newlen
< PAGE_SIZE
&& (new = malloc(n
-OVERHEAD
))) {
406 newlen
= (newlen
+ PAGE_SIZE
-1) & -PAGE_SIZE
;
407 if (oldlen
== newlen
) return p
;
408 base
= __mremap(base
, oldlen
, newlen
, MREMAP_MAYMOVE
);
409 if (base
== (void *)-1)
411 self
= (void *)(base
+ extra
);
412 self
->csize
= newlen
- extra
;
413 return CHUNK_TO_MEM(self
);
416 next
= NEXT_CHUNK(self
);
418 /* Crash on corrupted footer (likely from buffer overflow) */
419 if (next
->psize
!= self
->csize
) a_crash();
421 lock(mal
.split_merge_lock
);
423 size_t nsize
= next
->csize
& C_INUSE
? 0 : CHUNK_SIZE(next
);
425 int i
= bin_index(nsize
);
427 if (!(next
->csize
& C_INUSE
)) {
430 next
= NEXT_CHUNK(next
);
431 self
->csize
= next
->psize
= n0
+nsize
| C_INUSE
;
433 unlock(mal
.split_merge_lock
);
434 return CHUNK_TO_MEM(self
);
438 unlock(mal
.split_merge_lock
);
441 /* As a last resort, allocate a new chunk and copy to it. */
442 new = malloc(n
-OVERHEAD
);
445 memcpy(new, p
, n0
-OVERHEAD
);
446 free(CHUNK_TO_MEM(self
));
450 void __bin_chunk(struct chunk
*self
)
452 struct chunk
*next
= NEXT_CHUNK(self
);
454 /* Crash on corrupted footer (likely from buffer overflow) */
455 if (next
->psize
!= self
->csize
) a_crash();
457 lock(mal
.split_merge_lock
);
459 size_t osize
= CHUNK_SIZE(self
), size
= osize
;
461 /* Since we hold split_merge_lock, only transition from free to
462 * in-use can race; in-use to free is impossible */
463 size_t psize
= self
->psize
& C_INUSE
? 0 : CHUNK_PSIZE(self
);
464 size_t nsize
= next
->csize
& C_INUSE
? 0 : CHUNK_SIZE(next
);
467 int i
= bin_index(psize
);
469 if (!(self
->psize
& C_INUSE
)) {
470 struct chunk
*prev
= PREV_CHUNK(self
);
478 int i
= bin_index(nsize
);
480 if (!(next
->csize
& C_INUSE
)) {
482 next
= NEXT_CHUNK(next
);
488 int i
= bin_index(size
);
494 unlock(mal
.split_merge_lock
);
496 /* Replace middle of large chunks with fresh zero pages */
497 if (size
> RECLAIM
&& (size
^(size
-osize
)) > size
-osize
) {
498 uintptr_t a
= (uintptr_t)self
+ SIZE_ALIGN
+PAGE_SIZE
-1 & -PAGE_SIZE
;
499 uintptr_t b
= (uintptr_t)next
- SIZE_ALIGN
& -PAGE_SIZE
;
501 __madvise((void *)a
, b
-a
, MADV_DONTNEED
);
503 __mmap((void *)a
, b
-a
, PROT_READ
|PROT_WRITE
,
504 MAP_PRIVATE
|MAP_ANONYMOUS
|MAP_FIXED
, -1, 0);
511 static void unmap_chunk(struct chunk
*self
)
513 size_t extra
= self
->psize
;
514 char *base
= (char *)self
- extra
;
515 size_t len
= CHUNK_SIZE(self
) + extra
;
516 /* Crash on double free */
517 if (extra
& 1) a_crash();
525 struct chunk
*self
= MEM_TO_CHUNK(p
);
527 if (IS_MMAPPED(self
))
533 void __malloc_donate(char *start
, char *end
)
535 size_t align_start_up
= (SIZE_ALIGN
-1) & (-(uintptr_t)start
- OVERHEAD
);
536 size_t align_end_down
= (SIZE_ALIGN
-1) & (uintptr_t)end
;
538 /* Getting past this condition ensures that the padding for alignment
539 * and header overhead will not overflow and will leave a nonzero
540 * multiple of SIZE_ALIGN bytes between start and end. */
541 if (end
- start
<= OVERHEAD
+ align_start_up
+ align_end_down
)
543 start
+= align_start_up
+ OVERHEAD
;
544 end
-= align_end_down
;
546 struct chunk
*c
= MEM_TO_CHUNK(start
), *n
= MEM_TO_CHUNK(end
);
547 c
->psize
= n
->csize
= C_INUSE
;
548 c
->csize
= n
->psize
= C_INUSE
| (end
-start
);