1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * vdso_restorer.c - tests vDSO-based signal restore
4 * Copyright (c) 2015 Andrew Lutomirski
5 *
6 * This makes sure that sa_restorer == NULL keeps working on 32-bit
7 * configurations. Modern glibc doesn't use it under any circumstances,
8 * so it's easy to overlook breakage.
9 *
10 * 64-bit userspace has never supported sa_restorer == NULL, so this is
11 * 32-bit only.
12 */
13
14#define _GNU_SOURCE
15
16#include <err.h>
17#include <stdio.h>
18#include <dlfcn.h>
19#include <string.h>
20#include <signal.h>
21#include <unistd.h>
22#include <syscall.h>
23#include <sys/syscall.h>
24
25/* Open-code this -- the headers are too messy to easily use them. */
26struct real_sigaction {
27 void *handler;
28 unsigned long flags;
29 void *restorer;
30 unsigned int mask[2];
31};
32
33static volatile sig_atomic_t handler_called;
34
35static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
36{
37 handler_called = 1;
38}
39
40static void handler_without_siginfo(int sig)
41{
42 handler_called = 1;
43}
44
45int main()
46{
47 int nerrs = 0;
48 struct real_sigaction sa;
49
50 void *vdso = dlopen("linux-vdso.so.1",
51 RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
52 if (!vdso)
53 vdso = dlopen("linux-gate.so.1",
54 RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
55 if (!vdso) {
56 printf("[SKIP]\tFailed to find vDSO. Tests are not expected to work.\n");
57 return 0;
58 }
59
60 memset(&sa, 0, sizeof(sa));
61 sa.handler = handler_with_siginfo;
62 sa.flags = SA_SIGINFO;
63 sa.restorer = NULL; /* request kernel-provided restorer */
64
65 printf("[RUN]\tRaise a signal, SA_SIGINFO, sa.restorer == NULL\n");
66
67 if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
68 err(1, "raw rt_sigaction syscall");
69
70 raise(SIGUSR1);
71
72 if (handler_called) {
73 printf("[OK]\tSA_SIGINFO handler returned successfully\n");
74 } else {
75 printf("[FAIL]\tSA_SIGINFO handler was not called\n");
76 nerrs++;
77 }
78
79 printf("[RUN]\tRaise a signal, !SA_SIGINFO, sa.restorer == NULL\n");
80
81 sa.flags = 0;
82 sa.handler = handler_without_siginfo;
83 if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
84 err(1, "raw sigaction syscall");
85 handler_called = 0;
86
87 raise(SIGUSR1);
88
89 if (handler_called) {
90 printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
91 } else {
92 printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
93 nerrs++;
94 }
95}
96

source code of linux/tools/testing/selftests/x86/vdso_restorer.c