diff options
| -rw-r--r-- | util/mmap-alloc.c | 58 |
1 files changed, 33 insertions, 25 deletions
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 24854064b4..223d66219c 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -82,6 +82,38 @@ size_t qemu_mempath_getpagesize(const char *mem_path) return qemu_real_host_page_size; } +/* + * Reserve a new memory region of the requested size to be used for mapping + * from the given fd (if any). + */ +static void *mmap_reserve(size_t size, int fd) +{ + int flags = MAP_PRIVATE; + +#if defined(__powerpc64__) && defined(__linux__) + /* + * On ppc64 mappings in the same segment (aka slice) must share the same + * page size. Since we will be re-allocating part of this segment + * from the supplied fd, we should make sure to use the same page size, to + * this end we mmap the supplied fd. In this case, set MAP_NORESERVE to + * avoid allocating backing store memory. + * We do this unless we are using the system page size, in which case + * anonymous memory is OK. + */ + if (fd == -1 || qemu_fd_getpagesize(fd) == qemu_real_host_page_size) { + fd = -1; + flags |= MAP_ANONYMOUS; + } else { + flags |= MAP_NORESERVE; + } +#else + fd = -1; + flags |= MAP_ANONYMOUS; +#endif + + return mmap(0, size, PROT_NONE, flags, fd, 0); +} + static inline size_t mmap_guard_pagesize(int fd) { #if defined(__powerpc64__) && defined(__linux__) @@ -104,7 +136,6 @@ void *qemu_ram_mmap(int fd, int prot; int flags; int map_sync_flags = 0; - int guardfd; size_t offset; size_t total; void *guardptr; @@ -116,30 +147,7 @@ void *qemu_ram_mmap(int fd, */ total = size + align; -#if defined(__powerpc64__) && defined(__linux__) - /* On ppc64 mappings in the same segment (aka slice) must share the same - * page size. Since we will be re-allocating part of this segment - * from the supplied fd, we should make sure to use the same page size, to - * this end we mmap the supplied fd. In this case, set MAP_NORESERVE to - * avoid allocating backing store memory. - * We do this unless we are using the system page size, in which case - * anonymous memory is OK. - */ - flags = MAP_PRIVATE; - if (fd == -1 || guard_pagesize == qemu_real_host_page_size) { - guardfd = -1; - flags |= MAP_ANONYMOUS; - } else { - guardfd = fd; - flags |= MAP_NORESERVE; - } -#else - guardfd = -1; - flags = MAP_PRIVATE | MAP_ANONYMOUS; -#endif - - guardptr = mmap(0, total, PROT_NONE, flags, guardfd, 0); - + guardptr = mmap_reserve(total, fd); if (guardptr == MAP_FAILED) { return MAP_FAILED; } |