diff options
Diffstat (limited to 'malloc/malloc.c')
| -rw-r--r-- | malloc/malloc.c | 164 |
1 files changed, 88 insertions, 76 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index 57db4dd9a5..6b6ec53db1 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -2413,6 +2413,85 @@ do_check_malloc_state (mstate av) */ static void * +sysmalloc_mmap (INTERNAL_SIZE_T nb, size_t pagesize, int extra_flags, mstate av) +{ + long int size; + + /* + Round up size to nearest page. For mmapped chunks, the overhead is one + SIZE_SZ unit larger than for normal chunks, because there is no + following chunk whose prev_size field could be used. + + See the front_misalign handling below, for glibc there is no need for + further alignments unless we have have high alignment. + */ + if (MALLOC_ALIGNMENT == CHUNK_HDR_SZ) + size = ALIGN_UP (nb + SIZE_SZ, pagesize); + else + size = ALIGN_UP (nb + SIZE_SZ + MALLOC_ALIGN_MASK, pagesize); + + /* Don't try if size wraps around 0. */ + if ((unsigned long) (size) <= (unsigned long) (nb)) + return MAP_FAILED; + + char *mm = (char *) MMAP (0, size, + mtag_mmap_flags | PROT_READ | PROT_WRITE, + extra_flags); + if (mm == MAP_FAILED) + return mm; + + madvise_thp (mm, size); + + /* + The offset to the start of the mmapped region is stored in the prev_size + field of the chunk. This allows us to adjust returned start address to + meet alignment requirements here and in memalign(), and still be able to + compute proper address argument for later munmap in free() and realloc(). + */ + + INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of new space */ + + if (MALLOC_ALIGNMENT == CHUNK_HDR_SZ) + { + /* For glibc, chunk2mem increases the address by CHUNK_HDR_SZ and + MALLOC_ALIGN_MASK is CHUNK_HDR_SZ-1. Each mmap'ed area is page + aligned and therefore definitely MALLOC_ALIGN_MASK-aligned. */ + assert (((INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK) == 0); + front_misalign = 0; + } + else + front_misalign = (INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK; + + mchunkptr p; /* the allocated/returned chunk */ + + if (front_misalign > 0) + { + ptrdiff_t correction = MALLOC_ALIGNMENT - front_misalign; + p = (mchunkptr) (mm + correction); + set_prev_size (p, correction); + set_head (p, (size - correction) | IS_MMAPPED); + } + else + { + p = (mchunkptr) mm; + set_prev_size (p, 0); + set_head (p, size | IS_MMAPPED); + } + + /* update statistics */ + int new = atomic_exchange_and_add (&mp_.n_mmaps, 1) + 1; + atomic_max (&mp_.max_n_mmaps, new); + + unsigned long sum; + sum = atomic_exchange_and_add (&mp_.mmapped_mem, size) + size; + atomic_max (&mp_.max_mmapped_mem, sum); + + check_chunk (av, p); + + return chunk2mem (p); +} + +static void * sysmalloc (INTERNAL_SIZE_T nb, mstate av) { mchunkptr old_top; /* incoming value of av->top */ @@ -2449,81 +2528,10 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av) || ((unsigned long) (nb) >= (unsigned long) (mp_.mmap_threshold) && (mp_.n_mmaps < mp_.n_mmaps_max))) { - char *mm; /* return value from mmap call*/ - - try_mmap: - /* - Round up size to nearest page. For mmapped chunks, the overhead - is one SIZE_SZ unit larger than for normal chunks, because there - is no following chunk whose prev_size field could be used. - - See the front_misalign handling below, for glibc there is no - need for further alignments unless we have have high alignment. - */ - if (MALLOC_ALIGNMENT == CHUNK_HDR_SZ) - size = ALIGN_UP (nb + SIZE_SZ, pagesize); - else - size = ALIGN_UP (nb + SIZE_SZ + MALLOC_ALIGN_MASK, pagesize); + char *mm = sysmalloc_mmap (nb, pagesize, 0, av); + if (mm != MAP_FAILED) + return mm; tried_mmap = true; - - /* Don't try if size wraps around 0 */ - if ((unsigned long) (size) > (unsigned long) (nb)) - { - mm = (char *) (MMAP (0, size, - mtag_mmap_flags | PROT_READ | PROT_WRITE, 0)); - - if (mm != MAP_FAILED) - { - madvise_thp (mm, size); - - /* - The offset to the start of the mmapped region is stored - in the prev_size field of the chunk. This allows us to adjust - returned start address to meet alignment requirements here - and in memalign(), and still be able to compute proper - address argument for later munmap in free() and realloc(). - */ - - if (MALLOC_ALIGNMENT == CHUNK_HDR_SZ) - { - /* For glibc, chunk2mem increases the address by - CHUNK_HDR_SZ and MALLOC_ALIGN_MASK is - CHUNK_HDR_SZ-1. Each mmap'ed area is page - aligned and therefore definitely - MALLOC_ALIGN_MASK-aligned. */ - assert (((INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK) == 0); - front_misalign = 0; - } - else - front_misalign = (INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK; - if (front_misalign > 0) - { - correction = MALLOC_ALIGNMENT - front_misalign; - p = (mchunkptr) (mm + correction); - set_prev_size (p, correction); - set_head (p, (size - correction) | IS_MMAPPED); - } - else - { - p = (mchunkptr) mm; - set_prev_size (p, 0); - set_head (p, size | IS_MMAPPED); - } - - /* update statistics */ - - int new = atomic_exchange_and_add (&mp_.n_mmaps, 1) + 1; - atomic_max (&mp_.max_n_mmaps, new); - - unsigned long sum; - sum = atomic_exchange_and_add (&mp_.mmapped_mem, size) + size; - atomic_max (&mp_.max_mmapped_mem, sum); - - check_chunk (av, p); - - return chunk2mem (p); - } - } } /* There are no usable arenas and mmap also failed. */ @@ -2600,8 +2608,12 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av) } } else if (!tried_mmap) - /* We can at least try to use to mmap memory. */ - goto try_mmap; + { + /* We can at least try to use to mmap memory. */ + char *mm = sysmalloc_mmap (nb, pagesize, 0, av); + if (mm != MAP_FAILED) + return mm; + } } else /* av == main_arena */ |