1 #define JEMALLOC_CHUNK_MMAP_C_ 2 #include "jemalloc/internal/jemalloc_internal.h" 3 4 /******************************************************************************/ 5 6 static void * 7 chunk_alloc_mmap_slow(size_t size, size_t alignment, bool *zero, bool *commit) 8 { 9 void *ret; 10 size_t alloc_size; 11 12 alloc_size = size + alignment - PAGE; 13 /* Beware size_t wrap-around. */ 14 if (alloc_size < size) 15 return (NULL); 16 do { 17 void *pages; 18 size_t leadsize; 19 pages = pages_map(NULL, alloc_size, commit); 20 if (pages == NULL) 21 return (NULL); 22 leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment) - 23 (uintptr_t)pages; 24 ret = pages_trim(pages, alloc_size, leadsize, size, commit); 25 } while (ret == NULL); 26 27 assert(ret != NULL); 28 *zero = true; 29 return (ret); 30 } 31 32 void * 33 chunk_alloc_mmap(void *new_addr, size_t size, size_t alignment, bool *zero, 34 bool *commit) 35 { 36 void *ret; 37 size_t offset; 38 39 /* 40 * Ideally, there would be a way to specify alignment to mmap() (like 41 * NetBSD has), but in the absence of such a feature, we have to work 42 * hard to efficiently create aligned mappings. The reliable, but 43 * slow method is to create a mapping that is over-sized, then trim the 44 * excess. However, that always results in one or two calls to 45 * pages_unmap(). 46 * 47 * Optimistically try mapping precisely the right amount before falling 48 * back to the slow method, with the expectation that the optimistic 49 * approach works most of the time. 50 */ 51 52 assert(alignment != 0); 53 assert((alignment & chunksize_mask) == 0); 54 55 ret = pages_map(new_addr, size, commit); 56 if (ret == NULL || ret == new_addr) 57 return (ret); 58 assert(new_addr == NULL); 59 offset = ALIGNMENT_ADDR2OFFSET(ret, alignment); 60 if (offset != 0) { 61 pages_unmap(ret, size); 62 return (chunk_alloc_mmap_slow(size, alignment, zero, commit)); 63 } 64 65 assert(ret != NULL); 66 *zero = true; 67 return (ret); 68 } 69 70 bool 71 chunk_dalloc_mmap(void *chunk, size_t size) 72 { 73 74 if (config_munmap) 75 pages_unmap(chunk, size); 76 77 return (!config_munmap); 78 } 79
