void *
chunk_alloc_dss(size_t size, bool *zero)
{
void *ret;
ret = chunk_recycle_dss(size, zero);
if (ret != NULL)
return (ret);
/*
* sbrk() uses a signed increment argument, so take care not to
* interpret a huge allocation request as a negative increment.
*/
if ((intptr_t)size < 0)
return (NULL);
malloc_mutex_lock(&dss_mtx);
if (dss_prev != (void *)-1) {
intptr_t incr;
/*
* The loop is necessary to recover from races with other
* threads that are using the DSS for something other than
* malloc.
*/
do {
/* Get the current end of the DSS. */
dss_max = sbrk(0);
/*
* Calculate how much padding is necessary to
* chunk-align the end of the DSS.
*/
incr = (intptr_t)size
- (intptr_t)CHUNK_ADDR2OFFSET(dss_max);
if (incr == (intptr_t)size)
ret = dss_max;
else {
ret = (void *)((intptr_t)dss_max + incr);
incr += size;
}
dss_prev = sbrk(incr);
if (dss_prev == dss_max) {
/* Success. */
dss_max = (void *)((intptr_t)dss_prev + incr);
malloc_mutex_unlock(&dss_mtx);
*zero = true;
return (ret);
}
} while (dss_prev != (void *)-1);
}
malloc_mutex_unlock(&dss_mtx);
return (NULL);
}
static bool
huge_ralloc_no_move_shrink(void *ptr, size_t oldsize, size_t usize)
{
extent_node_t *node;
arena_t *arena;
chunk_hooks_t chunk_hooks;
size_t cdiff;
bool pre_zeroed, post_zeroed;
node = huge_node_get(ptr);
arena = extent_node_arena_get(node);
pre_zeroed = extent_node_zeroed_get(node);
chunk_hooks = chunk_hooks_get(arena);
assert(oldsize > usize);
/* Split excess chunks. */
cdiff = CHUNK_CEILING(oldsize) - CHUNK_CEILING(usize);
if (cdiff != 0 && chunk_hooks.split(ptr, CHUNK_CEILING(oldsize),
CHUNK_CEILING(usize), cdiff, true, arena->ind))
return (true);
if (oldsize > usize) {
size_t sdiff = oldsize - usize;
if (config_fill && unlikely(opt_junk_free)) {
huge_dalloc_junk((void *)((uintptr_t)ptr + usize),
sdiff);
post_zeroed = false;
} else {
post_zeroed = !chunk_purge_wrapper(arena, &chunk_hooks,
CHUNK_ADDR2BASE((uintptr_t)ptr + usize),
CHUNK_CEILING(oldsize),
CHUNK_ADDR2OFFSET((uintptr_t)ptr + usize), sdiff);
}
} else
post_zeroed = pre_zeroed;
malloc_mutex_lock(&arena->huge_mtx);
/* Update the size of the huge allocation. */
extent_node_size_set(node, usize);
/* Update zeroed. */
extent_node_zeroed_set(node, post_zeroed);
malloc_mutex_unlock(&arena->huge_mtx);
/* Zap the excess chunks. */
arena_chunk_ralloc_huge_shrink(arena, ptr, oldsize, usize);
return (false);
}
static void *
chunk_alloc_mmap_slow(size_t size, bool unaligned, bool noreserve)
{
void *ret;
size_t offset;
/* Beware size_t wrap-around. */
if (size + chunksize <= size)
return (NULL);
ret = pages_map(NULL, size + chunksize, noreserve);
if (ret == NULL)
return (NULL);
/* Clean up unneeded leading/trailing space. */
offset = CHUNK_ADDR2OFFSET(ret);
if (offset != 0) {
/* Note that mmap() returned an unaligned mapping. */
unaligned = true;
/* Leading space. */
pages_unmap(ret, chunksize - offset);
ret = (void *)((uintptr_t)ret +
(chunksize - offset));
/* Trailing space. */
pages_unmap((void *)((uintptr_t)ret + size),
offset);
} else {
/* Trailing space only. */
pages_unmap((void *)((uintptr_t)ret + size),
chunksize);
}
/*
* If mmap() returned an aligned mapping, reset mmap_unaligned so that
* the next chunk_alloc_mmap() execution tries the fast allocation
* method.
*/
if (unaligned == false)
MMAP_UNALIGNED_SET(false);
return (ret);
}
static void
huge_ralloc_no_move_shrink(void *ptr, size_t oldsize, size_t usize)
{
extent_node_t *node;
arena_t *arena;
chunk_purge_t *chunk_purge;
bool zeroed;
node = huge_node_get(ptr);
arena = extent_node_arena_get(node);
malloc_mutex_lock(&arena->lock);
chunk_purge = arena->chunk_purge;
malloc_mutex_unlock(&arena->lock);
if (oldsize > usize) {
size_t sdiff = oldsize - usize;
zeroed = !chunk_purge_wrapper(arena, chunk_purge,
CHUNK_ADDR2BASE((uintptr_t)ptr + usize),
CHUNK_ADDR2OFFSET((uintptr_t)ptr + usize), sdiff);
if (config_fill && unlikely(opt_junk_free)) {
huge_dalloc_junk((void *)((uintptr_t)ptr + usize),
sdiff);
zeroed = false;
}
} else
zeroed = true;
malloc_mutex_lock(&arena->huge_mtx);
/* Update the size of the huge allocation. */
extent_node_size_set(node, usize);
/* Clear node's zeroed field if zeroing failed above. */
extent_node_zeroed_set(node, extent_node_zeroed_get(node) && zeroed);
malloc_mutex_unlock(&arena->huge_mtx);
/* Zap the excess chunks. */
arena_chunk_ralloc_huge_shrink(arena, ptr, oldsize, usize);
}
void *
chunk_alloc_dss(size_t size, size_t alignment, bool *zero)
{
void *ret;
cassert(config_dss);
assert(size > 0 && (size & chunksize_mask) == 0);
assert(alignment > 0 && (alignment & chunksize_mask) == 0);
/*
* sbrk() uses a signed increment argument, so take care not to
* interpret a huge allocation request as a negative increment.
*/
if ((intptr_t)size < 0)
return (NULL);
malloc_mutex_lock(&dss_mtx);
if (dss_prev != (void *)-1) {
size_t gap_size, cpad_size;
void *cpad, *dss_next;
intptr_t incr;
/*
* The loop is necessary to recover from races with other
* threads that are using the DSS for something other than
* malloc.
*/
do {
/* Get the current end of the DSS. */
dss_max = sbrk(0);
/*
* Calculate how much padding is necessary to
* chunk-align the end of the DSS.
*/
gap_size = (chunksize - CHUNK_ADDR2OFFSET(dss_max)) &
chunksize_mask;
/*
* Compute how much chunk-aligned pad space (if any) is
* necessary to satisfy alignment. This space can be
* recycled for later use.
*/
cpad = (void *)((uintptr_t)dss_max + gap_size);
ret = (void *)ALIGNMENT_CEILING((uintptr_t)dss_max,
alignment);
cpad_size = (uintptr_t)ret - (uintptr_t)cpad;
dss_next = (void *)((uintptr_t)ret + size);
if ((uintptr_t)ret < (uintptr_t)dss_max ||
(uintptr_t)dss_next < (uintptr_t)dss_max) {
/* Wrap-around. */
malloc_mutex_unlock(&dss_mtx);
return (NULL);
}
incr = gap_size + cpad_size + size;
dss_prev = sbrk(incr);
if (dss_prev == dss_max) {
/* Success. */
dss_max = dss_next;
malloc_mutex_unlock(&dss_mtx);
if (cpad_size != 0)
chunk_dealloc(cpad, cpad_size, true);
if (*zero) {
VALGRIND_MAKE_MEM_UNDEFINED(ret, size);
memset(ret, 0, size);
}
return (ret);
}
} while (dss_prev != (void *)-1);
}
malloc_mutex_unlock(&dss_mtx);
return (NULL);
}
static void *
chunk_alloc_mmap_internal(size_t size, bool noreserve)
{
void *ret;
/*
* Ideally, there would be a way to specify alignment to mmap() (like
* NetBSD has), but in the absence of such a feature, we have to work
* hard to efficiently create aligned mappings. The reliable, but
* slow method is to create a mapping that is over-sized, then trim the
* excess. However, that always results in at least one call to
* pages_unmap().
*
* A more optimistic approach is to try mapping precisely the right
* amount, then try to append another mapping if alignment is off. In
* practice, this works out well as long as the application is not
* interleaving mappings via direct mmap() calls. If we do run into a
* situation where there is an interleaved mapping and we are unable to
* extend an unaligned mapping, our best option is to switch to the
* slow method until mmap() returns another aligned mapping. This will
* tend to leave a gap in the memory map that is too small to cause
* later problems for the optimistic method.
*
* Another possible confounding factor is address space layout
* randomization (ASLR), which causes mmap(2) to disregard the
* requested address. mmap_unaligned tracks whether the previous
* chunk_alloc_mmap() execution received any unaligned or relocated
* mappings, and if so, the current execution will immediately fall
* back to the slow method. However, we keep track of whether the fast
* method would have succeeded, and if so, we make a note to try the
* fast method next time.
*/
if (MMAP_UNALIGNED_GET() == false) {
size_t offset;
ret = pages_map(NULL, size, noreserve);
if (ret == NULL)
return (NULL);
offset = CHUNK_ADDR2OFFSET(ret);
if (offset != 0) {
MMAP_UNALIGNED_SET(true);
/* Try to extend chunk boundary. */
if (pages_map((void *)((uintptr_t)ret + size),
chunksize - offset, noreserve) == NULL) {
/*
* Extension failed. Clean up, then revert to
* the reliable-but-expensive method.
*/
pages_unmap(ret, size);
ret = chunk_alloc_mmap_slow(size, true,
noreserve);
} else {
/* Clean up unneeded leading space. */
pages_unmap(ret, chunksize - offset);
ret = (void *)((uintptr_t)ret + (chunksize -
offset));
}
}
} else
ret = chunk_alloc_mmap_slow(size, false, noreserve);
return (ret);
}
void *
chunk_alloc_dss(arena_t *arena, void *new_addr, size_t size, size_t alignment,
bool *zero, bool *commit)
{
cassert(have_dss);
assert(size > 0 && (size & chunksize_mask) == 0);
assert(alignment > 0 && (alignment & chunksize_mask) == 0);
/*
* sbrk() uses a signed increment argument, so take care not to
* interpret a huge allocation request as a negative increment.
*/
if ((intptr_t)size < 0)
return (NULL);
malloc_mutex_lock(&dss_mtx);
if (dss_prev != (void *)-1) {
/*
* The loop is necessary to recover from races with other
* threads that are using the DSS for something other than
* malloc.
*/
do {
void *ret, *cpad, *dss_next;
size_t gap_size, cpad_size;
intptr_t incr;
/* Avoid an unnecessary system call. */
if (new_addr != NULL && dss_max != new_addr)
break;
/* Get the current end of the DSS. */
dss_max = chunk_dss_sbrk(0);
/* Make sure the earlier condition still holds. */
if (new_addr != NULL && dss_max != new_addr)
break;
/*
* Calculate how much padding is necessary to
* chunk-align the end of the DSS.
*/
gap_size = (chunksize - CHUNK_ADDR2OFFSET(dss_max)) &
chunksize_mask;
/*
* Compute how much chunk-aligned pad space (if any) is
* necessary to satisfy alignment. This space can be
* recycled for later use.
*/
cpad = (void *)((uintptr_t)dss_max + gap_size);
ret = (void *)ALIGNMENT_CEILING((uintptr_t)dss_max,
alignment);
cpad_size = (uintptr_t)ret - (uintptr_t)cpad;
dss_next = (void *)((uintptr_t)ret + size);
if ((uintptr_t)ret < (uintptr_t)dss_max ||
(uintptr_t)dss_next < (uintptr_t)dss_max) {
/* Wrap-around. */
malloc_mutex_unlock(&dss_mtx);
return (NULL);
}
incr = gap_size + cpad_size + size;
dss_prev = chunk_dss_sbrk(incr);
if (dss_prev == dss_max) {
/* Success. */
dss_max = dss_next;
malloc_mutex_unlock(&dss_mtx);
if (cpad_size != 0) {
chunk_hooks_t chunk_hooks =
CHUNK_HOOKS_INITIALIZER;
chunk_dalloc_wrapper(arena,
&chunk_hooks, cpad, cpad_size,
true);
}
if (*zero) {
JEMALLOC_VALGRIND_MAKE_MEM_UNDEFINED(
ret, size);
memset(ret, 0, size);
}
if (!*commit)
*commit = pages_decommit(ret, size);
return (ret);
}
} while (dss_prev != (void *)-1);
}
malloc_mutex_unlock(&dss_mtx);
return (NULL);
}
