1 /* This testcase is part of GDB, the GNU debugger.
3 Copyright 2012-2018 Free Software Foundation, Inc.
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.
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.
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/>. */
24 #define CHUNK_SIZE 16000 /* same as findcmd.c's */
42 void *unmapped_page, *last_mapped_page, *first_mapped_page;
45 Map enough pages to cover at least CHUNK_SIZE, and one extra page. We
46 then unmap the last page.
48 From gdb we can then perform find commands into unmapped region, gdb
51 .-- global_var_0 .-- global_var_1
54 .----.----.----.----.----.
56 '----'----'----'----'----'
59 If CHUNK_SIZE equals page size then we'll get 3 pages, and if
60 CHUNK_SIZE is less than page size we'll get 2 pages. The test will
61 still work in these cases.
63 (1) We do a find from global_var_0 to global_var_2, this will fail when
64 loading the second chunk, as we know at least CHUNK_SIZE bytes are in
67 (2) We do a find from global_var_1 to global_var_2, this will fail when
68 loading the first chunk, assuming the CHUNK_SIZE is at least 16 bytes.
70 (3) We do a find from global_var_2 to (global_var_2 + 16), this too
71 will fail when loading the first chunk regardless of the chunk size.
74 pg_size = getpagesize ();
75 /* The +2 ensures the extra page. */
76 pg_count = CHUNK_SIZE / pg_size + 2;
78 p = mmap (0, pg_count * pg_size, PROT_READ|PROT_WRITE,
79 MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
86 memset (p, 0, pg_count * pg_size);
88 if (munmap (p + (pg_count - 1) * pg_size, pg_size) == -1)
94 first_mapped_page = p;
95 last_mapped_page = p + (pg_count - 2) * pg_size;
96 unmapped_page = last_mapped_page + pg_size;
98 /* Setup global variables we reference from gdb. */
99 global_var_0 = first_mapped_page;
100 global_var_1 = unmapped_page - 16;
101 global_var_2 = unmapped_page + 16;