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Bug 956501 - Update mozjemalloc chunk_alloc_mmap functions to latest upstream version r=glandium
This commit is contained in:
Jon Coppeard
parent
d3576156a7
commit
0956f2e4d6
@ -2698,137 +2698,85 @@ RETURN:
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#else /* ! (defined(MOZ_MEMORY_WINDOWS) || defined(JEMALLOC_USES_MAP_ALIGN) || defined(MALLOC_PAGEFILE)) */
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/*
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* Used by chunk_alloc_mmap() to decide whether to attempt the fast path and
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* potentially avoid some system calls.
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*/
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#ifndef NO_TLS
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static __thread bool mmap_unaligned_tls __attribute__((tls_model("initial-exec")));
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#define MMAP_UNALIGNED_GET() mmap_unaligned_tls
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#define MMAP_UNALIGNED_SET(v) do { \
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mmap_unaligned_tls = (v); \
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} while (0)
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#else
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#define NEEDS_PTHREAD_MMAP_UNALIGNED_TSD
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static pthread_key_t mmap_unaligned_tsd;
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#define MMAP_UNALIGNED_GET() ((bool)pthread_getspecific(mmap_unaligned_tsd))
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#define MMAP_UNALIGNED_SET(v) do { \
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pthread_setspecific(mmap_unaligned_tsd, (void *)(v)); \
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} while (0)
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#endif
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/* pages_trim, chunk_alloc_mmap_slow and chunk_alloc_mmap were cherry-picked
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* from upstream jemalloc 3.4.1 to fix Mozilla bug 956501. */
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/* chunk_alloc_mmap_slow and chunk_alloc_mmap were cherry-picked from upstream
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* jemalloc 2.2.3 to fix Mozilla bug 694896, enable jemalloc on Mac 10.7. */
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/* Return the offset between a and the nearest aligned address at or below a. */
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#define ALIGNMENT_ADDR2OFFSET(a, alignment) \
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((size_t)((uintptr_t)(a) & (alignment - 1)))
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/* Return the smallest alignment multiple that is >= s. */
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#define ALIGNMENT_CEILING(s, alignment) \
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(((s) + (alignment - 1)) & (-(alignment)))
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static void *
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chunk_alloc_mmap_slow(size_t size, bool unaligned)
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pages_trim(void *addr, size_t alloc_size, size_t leadsize, size_t size)
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{
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void *ret;
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size_t offset;
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void *ret = (void *)((uintptr_t)addr + leadsize);
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/* Beware size_t wrap-around. */
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if (size + chunksize <= size)
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return (NULL);
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assert(alloc_size >= leadsize + size);
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size_t trailsize = alloc_size - leadsize - size;
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ret = pages_map(NULL, size + chunksize, -1);
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if (ret == NULL)
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return (NULL);
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if (leadsize != 0)
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pages_unmap(addr, leadsize);
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if (trailsize != 0)
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pages_unmap((void *)((uintptr_t)ret + size), trailsize);
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return (ret);
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}
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/* Clean up unneeded leading/trailing space. */
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offset = CHUNK_ADDR2OFFSET(ret);
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if (offset != 0) {
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/* Note that mmap() returned an unaligned mapping. */
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unaligned = true;
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static void *
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chunk_alloc_mmap_slow(size_t size, size_t alignment)
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{
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void *ret, *pages;
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size_t alloc_size, leadsize;
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/* Leading space. */
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pages_unmap(ret, chunksize - offset);
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alloc_size = size + alignment - pagesize;
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/* Beware size_t wrap-around. */
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if (alloc_size < size)
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return (NULL);
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do {
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pages = pages_map(NULL, alloc_size, -1);
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if (pages == NULL)
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return (NULL);
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leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment) -
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(uintptr_t)pages;
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ret = pages_trim(pages, alloc_size, leadsize, size);
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} while (ret == NULL);
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ret = (void *)((uintptr_t)ret +
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(chunksize - offset));
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/* Trailing space. */
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pages_unmap((void *)((uintptr_t)ret + size),
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offset);
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} else {
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/* Trailing space only. */
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pages_unmap((void *)((uintptr_t)ret + size),
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chunksize);
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}
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/*
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* If mmap() returned an aligned mapping, reset mmap_unaligned so that
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* the next chunk_alloc_mmap() execution tries the fast allocation
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* method.
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*/
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if (unaligned == false)
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MMAP_UNALIGNED_SET(false);
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return (ret);
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assert(ret != NULL);
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return (ret);
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}
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static void *
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chunk_alloc_mmap(size_t size, bool pagefile)
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{
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void *ret;
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void *ret;
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size_t offset;
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/*
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* Ideally, there would be a way to specify alignment to mmap() (like
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* NetBSD has), but in the absence of such a feature, we have to work
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* hard to efficiently create aligned mappings. The reliable, but
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* slow method is to create a mapping that is over-sized, then trim the
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* excess. However, that always results in at least one call to
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* pages_unmap().
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*
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* A more optimistic approach is to try mapping precisely the right
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* amount, then try to append another mapping if alignment is off. In
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* practice, this works out well as long as the application is not
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* interleaving mappings via direct mmap() calls. If we do run into a
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* situation where there is an interleaved mapping and we are unable to
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* extend an unaligned mapping, our best option is to switch to the
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* slow method until mmap() returns another aligned mapping. This will
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* tend to leave a gap in the memory map that is too small to cause
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* later problems for the optimistic method.
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*
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* Another possible confounding factor is address space layout
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* randomization (ASLR), which causes mmap(2) to disregard the
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* requested address. mmap_unaligned tracks whether the previous
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* chunk_alloc_mmap() execution received any unaligned or relocated
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* mappings, and if so, the current execution will immediately fall
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* back to the slow method. However, we keep track of whether the fast
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* method would have succeeded, and if so, we make a note to try the
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* fast method next time.
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*/
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/*
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* Ideally, there would be a way to specify alignment to mmap() (like
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* NetBSD has), but in the absence of such a feature, we have to work
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* hard to efficiently create aligned mappings. The reliable, but
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* slow method is to create a mapping that is over-sized, then trim the
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* excess. However, that always results in one or two calls to
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* pages_unmap().
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*
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* Optimistically try mapping precisely the right amount before falling
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* back to the slow method, with the expectation that the optimistic
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* approach works most of the time.
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*/
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if (MMAP_UNALIGNED_GET() == false) {
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size_t offset;
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ret = pages_map(NULL, size, -1);
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if (ret == NULL)
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return (NULL);
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offset = ALIGNMENT_ADDR2OFFSET(ret, chunksize);
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if (offset != 0) {
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pages_unmap(ret, size);
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return (chunk_alloc_mmap_slow(size, chunksize));
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}
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ret = pages_map(NULL, size, -1);
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if (ret == NULL)
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return (NULL);
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offset = CHUNK_ADDR2OFFSET(ret);
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if (offset != 0) {
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MMAP_UNALIGNED_SET(true);
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/* Try to extend chunk boundary. */
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if (pages_map((void *)((uintptr_t)ret + size),
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chunksize - offset, -1) == NULL) {
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/*
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* Extension failed. Clean up, then revert to
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* the reliable-but-expensive method.
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*/
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pages_unmap(ret, size);
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ret = chunk_alloc_mmap_slow(size, true);
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} else {
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/* Clean up unneeded leading space. */
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pages_unmap(ret, chunksize - offset);
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ret = (void *)((uintptr_t)ret + (chunksize -
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offset));
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}
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}
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} else
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ret = chunk_alloc_mmap_slow(size, false);
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return (ret);
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assert(ret != NULL);
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return (ret);
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}
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#endif /* defined(MOZ_MEMORY_WINDOWS) || defined(JEMALLOC_USES_MAP_ALIGN) || defined(MALLOC_PAGEFILE) */
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