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#define JEMALLOC_CHUNK_MMAP_C_
#include "jemalloc/internal/jemalloc_internal.h"
/******************************************************************************/
/* Function prototypes for non-inline static functions. */
static void *pages_map(void *addr, size_t size);
static void pages_unmap(void *addr, size_t size);
static void *chunk_alloc_mmap_slow(size_t size, size_t alignment,
bool *zero);
/******************************************************************************/
static void *
pages_map(void *addr, size_t size)
{
void *ret;
assert(size != 0);
#ifdef _WIN32
/*
* If VirtualAlloc can't allocate at the given address when one is
* given, it fails and returns NULL.
*/
ret = VirtualAlloc(addr, size, MEM_COMMIT | MEM_RESERVE,
PAGE_READWRITE);
#else
/*
* We don't use MAP_FIXED here, because it can cause the *replacement*
* of existing mappings, and we only want to create new mappings.
*/
ret = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON,
-1, 0);
assert(ret != NULL);
if (ret == MAP_FAILED)
ret = NULL;
else if (addr != NULL && ret != addr) {
/*
* We succeeded in mapping memory, but not in the right place.
*/
if (munmap(ret, size) == -1) {
char buf[BUFERROR_BUF];
buferror(buf, sizeof(buf));
malloc_printf("<jemalloc: Error in munmap(): %s\n",
buf);
if (opt_abort)
abort();
}
ret = NULL;
}
#endif
assert(ret == NULL || (addr == NULL && ret != addr)
|| (addr != NULL && ret == addr));
return (ret);
}
static void
pages_unmap(void *addr, size_t size)
{
#ifdef _WIN32
if (VirtualFree(addr, 0, MEM_RELEASE) == 0)
#else
if (munmap(addr, size) == -1)
#endif
{
char buf[BUFERROR_BUF];
buferror(buf, sizeof(buf));
malloc_printf("<jemalloc>: Error in "
#ifdef _WIN32
"VirtualFree"
#else
"munmap"
#endif
"(): %s\n", buf);
if (opt_abort)
abort();
}
}
static void *
pages_trim(void *addr, size_t alloc_size, size_t leadsize, size_t size)
{
void *ret = (void *)((uintptr_t)addr + leadsize);
assert(alloc_size >= leadsize + size);
#ifdef _WIN32
{
void *new_addr;
pages_unmap(addr, alloc_size);
new_addr = pages_map(ret, size);
if (new_addr == ret)
return (ret);
if (new_addr)
pages_unmap(new_addr, size);
return (NULL);
}
#else
{
size_t trailsize = alloc_size - leadsize - size;
if (leadsize != 0)
pages_unmap(addr, leadsize);
if (trailsize != 0)
pages_unmap((void *)((uintptr_t)ret + size), trailsize);
return (ret);
}
#endif
}
bool
pages_purge(void *addr, size_t length)
{
bool unzeroed;
#ifdef _WIN32
VirtualAlloc(addr, length, MEM_RESET, PAGE_READWRITE);
unzeroed = true;
#else
# ifdef JEMALLOC_PURGE_MADVISE_DONTNEED
# define JEMALLOC_MADV_PURGE MADV_DONTNEED
# define JEMALLOC_MADV_ZEROS true
# elif defined(JEMALLOC_PURGE_MADVISE_FREE)
# define JEMALLOC_MADV_PURGE MADV_FREE
# define JEMALLOC_MADV_ZEROS false
# else
# error "No method defined for purging unused dirty pages."
# endif
int err = madvise(addr, length, JEMALLOC_MADV_PURGE);
unzeroed = (JEMALLOC_MADV_ZEROS == false || err != 0);
# undef JEMALLOC_MADV_PURGE
# undef JEMALLOC_MADV_ZEROS
#endif
return (unzeroed);
}
static void *
chunk_alloc_mmap_slow(size_t size, size_t alignment, bool *zero)
{
void *ret, *pages;
size_t alloc_size, leadsize;
alloc_size = size + alignment - PAGE;
/* Beware size_t wrap-around. */
if (alloc_size < size)
return (NULL);
do {
pages = pages_map(NULL, alloc_size);
if (pages == NULL)
return (NULL);
leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment) -
(uintptr_t)pages;
ret = pages_trim(pages, alloc_size, leadsize, size);
} while (ret == NULL);
assert(ret != NULL);
*zero = true;
return (ret);
}
void *
chunk_alloc_mmap(size_t size, size_t alignment, bool *zero)
{
void *ret;
size_t offset;
/*
* 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 one or two calls to
* pages_unmap().
*
* Optimistically try mapping precisely the right amount before falling
* back to the slow method, with the expectation that the optimistic
* approach works most of the time.
*/
assert(alignment != 0);
assert((alignment & chunksize_mask) == 0);
ret = pages_map(NULL, size);
if (ret == NULL)
return (NULL);
offset = ALIGNMENT_ADDR2OFFSET(ret, alignment);
if (offset != 0) {
pages_unmap(ret, size);
return (chunk_alloc_mmap_slow(size, alignment, zero));
}
assert(ret != NULL);
*zero = true;
return (ret);
}
bool
chunk_dealloc_mmap(void *chunk, size_t size)
{
if (config_munmap)
pages_unmap(chunk, size);
return (config_munmap == false);
}
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