1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Test that we can take signals with and without the VDSO mapped, which trigger
4 * different paths in the signal handling code.
5 *
6 * See handle_rt_signal64() and setup_trampoline() in signal_64.c
7 */
8
9#define _GNU_SOURCE
10
11#include <errno.h>
12#include <stdio.h>
13#include <signal.h>
14#include <stdlib.h>
15#include <string.h>
16#include <sys/mman.h>
17#include <sys/types.h>
18#include <unistd.h>
19
20// Ensure assert() is not compiled out
21#undef NDEBUG
22#include <assert.h>
23
24#include "utils.h"
25
26static int search_proc_maps(char *needle, unsigned long *low, unsigned long *high)
27{
28	unsigned long start, end;
29	static char buf[4096];
30	char name[128];
31	FILE *f;
32	int rc = -1;
33
34	f = fopen("/proc/self/maps", "r");
35	if (!f) {
36		perror("fopen");
37		return -1;
38	}
39
40	while (fgets(buf, sizeof(buf), f)) {
41		rc = sscanf(buf, "%lx-%lx %*c%*c%*c%*c %*x %*d:%*d %*d %127s\n",
42			    &start, &end, name);
43		if (rc == 2)
44			continue;
45
46		if (rc != 3) {
47			printf("sscanf errored\n");
48			rc = -1;
49			break;
50		}
51
52		if (strstr(name, needle)) {
53			*low = start;
54			*high = end - 1;
55			rc = 0;
56			break;
57		}
58	}
59
60	fclose(f);
61
62	return rc;
63}
64
65static volatile sig_atomic_t took_signal = 0;
66
67static void sigusr1_handler(int sig)
68{
69	took_signal++;
70}
71
72int test_sigreturn_vdso(void)
73{
74	unsigned long low, high, size;
75	struct sigaction act;
76	char *p;
77
78	act.sa_handler = sigusr1_handler;
79	act.sa_flags = 0;
80	sigemptyset(&act.sa_mask);
81
82	assert(sigaction(SIGUSR1, &act, NULL) == 0);
83
84	// Confirm the VDSO is mapped, and work out where it is
85	assert(search_proc_maps("[vdso]", &low, &high) == 0);
86	size = high - low + 1;
87	printf("VDSO is at 0x%lx-0x%lx (%lu bytes)\n", low, high, size);
88
89	kill(getpid(), SIGUSR1);
90	assert(took_signal == 1);
91	printf("Signal delivered OK with VDSO mapped\n");
92
93	// Remap the VDSO somewhere else
94	p = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
95	assert(p != MAP_FAILED);
96	assert(mremap((void *)low, size, size, MREMAP_MAYMOVE|MREMAP_FIXED, p) != MAP_FAILED);
97	assert(search_proc_maps("[vdso]", &low, &high) == 0);
98	size = high - low + 1;
99	printf("VDSO moved to 0x%lx-0x%lx (%lu bytes)\n", low, high, size);
100
101	kill(getpid(), SIGUSR1);
102	assert(took_signal == 2);
103	printf("Signal delivered OK with VDSO moved\n");
104
105	assert(munmap((void *)low, size) == 0);
106	printf("Unmapped VDSO\n");
107
108	// Confirm the VDSO is not mapped anymore
109	assert(search_proc_maps("[vdso]", &low, &high) != 0);
110
111	// Make the stack executable
112	assert(search_proc_maps("[stack]", &low, &high) == 0);
113	size = high - low + 1;
114	mprotect((void *)low, size, PROT_READ|PROT_WRITE|PROT_EXEC);
115	printf("Remapped the stack executable\n");
116
117	kill(getpid(), SIGUSR1);
118	assert(took_signal == 3);
119	printf("Signal delivered OK with VDSO unmapped\n");
120
121	return 0;
122}
123
124int main(void)
125{
126	return test_harness(test_sigreturn_vdso, "sigreturn_vdso");
127}
128