tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 <string.h>
19#include <signal.h>
20#include <unistd.h>
21#include <syscall.h>
22#include <sys/syscall.h>
23
24/* Open-code this -- the headers are too messy to easily use them. */
25struct real_sigaction {
26 void *handler;
27 unsigned long flags;
28 void *restorer;
29 unsigned int mask[2];
30};
31
32static volatile sig_atomic_t handler_called;
33
34static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
35{
36 handler_called = 1;
37}
38
39static void handler_without_siginfo(int sig)
40{
41 handler_called = 1;
42}
43
44int main()
45{
46 int nerrs = 0;
47 struct real_sigaction sa;
48
49 memset(&sa, 0, sizeof(sa));
50 sa.handler = handler_with_siginfo;
51 sa.flags = SA_SIGINFO;
52 sa.restorer = NULL; /* request kernel-provided restorer */
53
54 if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
55 err(1, "raw rt_sigaction syscall");
56
57 raise(SIGUSR1);
58
59 if (handler_called) {
60 printf("[OK]\tSA_SIGINFO handler returned successfully\n");
61 } else {
62 printf("[FAIL]\tSA_SIGINFO handler was not called\n");
63 nerrs++;
64 }
65
66 sa.flags = 0;
67 sa.handler = handler_without_siginfo;
68 if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
69 err(1, "raw sigaction syscall");
70 handler_called = 0;
71
72 raise(SIGUSR1);
73
74 if (handler_called) {
75 printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
76 } else {
77 printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
78 nerrs++;
79 }
80}