| /* Memory allocation next to an unmapped page. |
| Copyright (C) 2017-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <support/check.h> |
| #include <support/next_to_fault.h> |
| #include <support/xunistd.h> |
| #include <sys/mman.h> |
| #include <sys/param.h> |
| |
| struct support_next_to_fault |
| support_next_to_fault_allocate (size_t size) |
| { |
| long page_size = sysconf (_SC_PAGE_SIZE); |
| TEST_VERIFY_EXIT (page_size > 0); |
| struct support_next_to_fault result; |
| result.region_size = roundup (size, page_size) + page_size; |
| if (size + page_size <= size || result.region_size <= size) |
| FAIL_EXIT1 ("support_next_to_fault_allocate (%zu): overflow", size); |
| result.region_start |
| = xmmap (NULL, result.region_size, PROT_READ | PROT_WRITE, |
| MAP_PRIVATE | MAP_ANONYMOUS, -1); |
| /* Unmap the page after the allocation. */ |
| xmprotect (result.region_start + (result.region_size - page_size), |
| page_size, PROT_NONE); |
| /* Align the allocation within the region so that it ends just |
| before the PROT_NONE page. */ |
| result.buffer = result.region_start + result.region_size - page_size - size; |
| result.length = size; |
| return result; |
| } |
| |
| void |
| support_next_to_fault_free (struct support_next_to_fault *ntf) |
| { |
| xmunmap (ntf->region_start, ntf->region_size); |
| *ntf = (struct support_next_to_fault) { NULL, }; |
| } |