1 | // SPDX-License-Identifier: GPL-2.0 |
2 | |
3 | /* |
4 | * Copyright 2017 John Sperbeck |
5 | * |
6 | * Test that an access to a mapped but inaccessible area causes a SEGV and |
7 | * reports si_code == SEGV_ACCERR. |
8 | */ |
9 | |
10 | #include <stdbool.h> |
11 | #include <stdio.h> |
12 | #include <stdlib.h> |
13 | #include <string.h> |
14 | #include <unistd.h> |
15 | #include <signal.h> |
16 | #include <sys/mman.h> |
17 | #include <assert.h> |
18 | #include <ucontext.h> |
19 | |
20 | #include "utils.h" |
21 | |
22 | static bool faulted; |
23 | static int si_code; |
24 | |
25 | static void segv_handler(int n, siginfo_t *info, void *ctxt_v) |
26 | { |
27 | ucontext_t *ctxt = (ucontext_t *)ctxt_v; |
28 | struct pt_regs *regs = ctxt->uc_mcontext.regs; |
29 | |
30 | faulted = true; |
31 | si_code = info->si_code; |
32 | regs->nip += 4; |
33 | } |
34 | |
35 | int test_segv_errors(void) |
36 | { |
37 | struct sigaction act = { |
38 | .sa_sigaction = segv_handler, |
39 | .sa_flags = SA_SIGINFO, |
40 | }; |
41 | char c, *p = NULL; |
42 | |
43 | p = mmap(NULL, getpagesize(), 0, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); |
44 | FAIL_IF(p == MAP_FAILED); |
45 | |
46 | FAIL_IF(sigaction(SIGSEGV, &act, NULL) != 0); |
47 | |
48 | faulted = false; |
49 | si_code = 0; |
50 | |
51 | /* |
52 | * We just need a compiler barrier, but mb() works and has the nice |
53 | * property of being easy to spot in the disassembly. |
54 | */ |
55 | mb(); |
56 | c = *p; |
57 | mb(); |
58 | |
59 | FAIL_IF(!faulted); |
60 | FAIL_IF(si_code != SEGV_ACCERR); |
61 | |
62 | faulted = false; |
63 | si_code = 0; |
64 | |
65 | mb(); |
66 | *p = c; |
67 | mb(); |
68 | |
69 | FAIL_IF(!faulted); |
70 | FAIL_IF(si_code != SEGV_ACCERR); |
71 | |
72 | return 0; |
73 | } |
74 | |
75 | int main(void) |
76 | { |
77 | return test_harness(test_segv_errors, "segv_errors" ); |
78 | } |
79 | |