1 /* This testcase is part of GDB, the GNU debugger. 2 3 Copyright 2012-2020 Free Software Foundation, Inc. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18 #include <stdlib.h> 19 #include <stdio.h> 20 #include <sys/mman.h> 21 #include <unistd.h> 22 #include <string.h> 23 24 size_t pg_size; 25 void *first_mapped_page; 26 void *last_mapped_page; 27 28 void 29 breakpt (void) 30 { 31 /* Nothing. */ 32 } 33 34 int 35 main (void) 36 { 37 void *p; 38 int pg_count; 39 size_t i; 40 41 /* Map 6 contiguous pages, and then unmap all second first, and 42 second last. 43 44 From GDB we will disassemble each of the _mapped_ pages, with a 45 code-cache (dcache) line size bigger than the page size (twice 46 bigger). This makes GDB try to read one page before the mapped 47 page once, and the page after another time. GDB should give no 48 error in either case. 49 50 That is, depending on where the kernel aligns the pages, we get 51 either: 52 53 .---.---.---.---.---.---. 54 | U | M | U | U | M | U | 55 '---'---'---'---'---'---. 56 | | | | <- line alignment 57 ^^^^^^^ ^^^^^^^ 58 | | 59 + line1 + line2 60 61 Or: 62 63 .---.---.---.---.---.---. 64 | U | M | U | U | M | U | 65 '---'---'---'---'---'---. 66 | | | <- line alignment 67 ^^^^^^^ ^^^^^^^ 68 | | 69 line1 + + line2 70 71 Note we really want to test that dcache behaves correctly when 72 reading a cache line fails. We're just using unmapped memory as 73 proxy for any kind of error. */ 74 75 pg_size = getpagesize (); 76 pg_count = 6; 77 78 p = mmap (0, pg_count * pg_size, PROT_READ|PROT_WRITE, 79 MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); 80 if (p == MAP_FAILED) 81 { 82 perror ("mmap"); 83 return EXIT_FAILURE; 84 } 85 86 /* Leave memory zero-initialized. Disassembling 0s should behave on 87 all targets. */ 88 89 for (i = 0; i < pg_count; i++) 90 { 91 if (i == 1 || i == 4) 92 continue; 93 94 if (munmap (p + (i * pg_size), pg_size) == -1) 95 { 96 perror ("munmap"); 97 return EXIT_FAILURE; 98 } 99 } 100 101 first_mapped_page = p + 1 * pg_size;; 102 last_mapped_page = p + 4 * pg_size; 103 104 breakpt (); 105 106 return EXIT_SUCCESS; 107 } 108