diff options
Diffstat (limited to 'externals/jemalloc/chunk_mmap.c')
| -rw-r--r-- | externals/jemalloc/chunk_mmap.c | 201 |
1 files changed, 0 insertions, 201 deletions
diff --git a/externals/jemalloc/chunk_mmap.c b/externals/jemalloc/chunk_mmap.c deleted file mode 100644 index 8f0711384e3..00000000000 --- a/externals/jemalloc/chunk_mmap.c +++ /dev/null @@ -1,201 +0,0 @@ -#define JEMALLOC_CHUNK_MMAP_C_ -#include "jemalloc/internal/jemalloc_internal.h" - -/******************************************************************************/ -/* Data. */ - -/* - * Used by chunk_alloc_mmap() to decide whether to attempt the fast path and - * potentially avoid some system calls. We can get away without TLS here, - * since the state of mmap_unaligned only affects performance, rather than - * correct function. - */ -static -#ifndef NO_TLS - __thread -#endif - bool mmap_unaligned -#ifndef NO_TLS - JEMALLOC_ATTR(tls_model("initial-exec")) -#endif - ; - -/******************************************************************************/ -/* 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, bool unaligned); - -/******************************************************************************/ - -static void * -pages_map(void *addr, size_t size) -{ - void *ret; - - /* - * 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[STRERROR_BUF]; - - strerror_r(errno, buf, sizeof(buf)); - malloc_write("<jemalloc>: Error in munmap(): "); - malloc_write(buf); - malloc_write("\n"); - if (opt_abort) - abort(); - } - ret = NULL; - } - - assert(ret == NULL || (addr == NULL && ret != addr) - || (addr != NULL && ret == addr)); - return (ret); -} - -static void -pages_unmap(void *addr, size_t size) -{ - - if (munmap(addr, size) == -1) { - char buf[STRERROR_BUF]; - - strerror_r(errno, buf, sizeof(buf)); - malloc_write("<jemalloc>: Error in munmap(): "); - malloc_write(buf); - malloc_write("\n"); - if (opt_abort) - abort(); - } -} - -static void * -chunk_alloc_mmap_slow(size_t size, bool unaligned) -{ - void *ret; - size_t offset; - - /* Beware size_t wrap-around. */ - if (size + chunksize <= size) - return (NULL); - - ret = pages_map(NULL, size + chunksize); - 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 = false; - - return (ret); -} - -void * -chunk_alloc_mmap(size_t size) -{ - 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 == false) { - size_t offset; - - ret = pages_map(NULL, size); - if (ret == NULL) - return (NULL); - - offset = CHUNK_ADDR2OFFSET(ret); - if (offset != 0) { - mmap_unaligned = true; - /* Try to extend chunk boundary. */ - if (pages_map((void *)((uintptr_t)ret + size), - chunksize - offset) == NULL) { - /* - * Extension failed. Clean up, then revert to - * the reliable-but-expensive method. - */ - pages_unmap(ret, size); - ret = chunk_alloc_mmap_slow(size, true); - } 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); - - return (ret); -} - -void -chunk_dealloc_mmap(void *chunk, size_t size) -{ - - pages_unmap(chunk, size); -} |