1 // SPDX-License-Identifier: GPL-2.0
2 #include <test_progs.h>
3 #include <sys/time.h>
4 #include <sys/resource.h>
5 #include "test_send_signal_kern.skel.h"
6 
7 int sigusr1_received = 0;
8 
sigusr1_handler(int signum)9 static void sigusr1_handler(int signum)
10 {
11 	sigusr1_received++;
12 }
13 
test_send_signal_common(struct perf_event_attr * attr,bool signal_thread)14 static void test_send_signal_common(struct perf_event_attr *attr,
15 				    bool signal_thread)
16 {
17 	struct test_send_signal_kern *skel;
18 	int pipe_c2p[2], pipe_p2c[2];
19 	int err = -1, pmu_fd = -1;
20 	char buf[256];
21 	pid_t pid;
22 
23 	if (!ASSERT_OK(pipe(pipe_c2p), "pipe_c2p"))
24 		return;
25 
26 	if (!ASSERT_OK(pipe(pipe_p2c), "pipe_p2c")) {
27 		close(pipe_c2p[0]);
28 		close(pipe_c2p[1]);
29 		return;
30 	}
31 
32 	pid = fork();
33 	if (!ASSERT_GE(pid, 0, "fork")) {
34 		close(pipe_c2p[0]);
35 		close(pipe_c2p[1]);
36 		close(pipe_p2c[0]);
37 		close(pipe_p2c[1]);
38 		return;
39 	}
40 
41 	if (pid == 0) {
42 		int old_prio;
43 
44 		/* install signal handler and notify parent */
45 		signal(SIGUSR1, sigusr1_handler);
46 
47 		close(pipe_c2p[0]); /* close read */
48 		close(pipe_p2c[1]); /* close write */
49 
50 		/* boost with a high priority so we got a higher chance
51 		 * that if an interrupt happens, the underlying task
52 		 * is this process.
53 		 */
54 		errno = 0;
55 		old_prio = getpriority(PRIO_PROCESS, 0);
56 		ASSERT_OK(errno, "getpriority");
57 		ASSERT_OK(setpriority(PRIO_PROCESS, 0, -20), "setpriority");
58 
59 		/* notify parent signal handler is installed */
60 		ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");
61 
62 		/* make sure parent enabled bpf program to send_signal */
63 		ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");
64 
65 		/* wait a little for signal handler */
66 		sleep(1);
67 
68 		buf[0] = sigusr1_received ? '2' : '0';
69 		ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");
70 
71 		/* wait for parent notification and exit */
72 		ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");
73 
74 		/* restore the old priority */
75 		ASSERT_OK(setpriority(PRIO_PROCESS, 0, old_prio), "setpriority");
76 
77 		close(pipe_c2p[1]);
78 		close(pipe_p2c[0]);
79 		exit(0);
80 	}
81 
82 	close(pipe_c2p[1]); /* close write */
83 	close(pipe_p2c[0]); /* close read */
84 
85 	skel = test_send_signal_kern__open_and_load();
86 	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
87 		goto skel_open_load_failure;
88 
89 	if (!attr) {
90 		err = test_send_signal_kern__attach(skel);
91 		if (!ASSERT_OK(err, "skel_attach")) {
92 			err = -1;
93 			goto destroy_skel;
94 		}
95 	} else {
96 		pmu_fd = syscall(__NR_perf_event_open, attr, pid, -1,
97 				 -1 /* group id */, 0 /* flags */);
98 		if (!ASSERT_GE(pmu_fd, 0, "perf_event_open")) {
99 			err = -1;
100 			goto destroy_skel;
101 		}
102 
103 		skel->links.send_signal_perf =
104 			bpf_program__attach_perf_event(skel->progs.send_signal_perf, pmu_fd);
105 		if (!ASSERT_OK_PTR(skel->links.send_signal_perf, "attach_perf_event"))
106 			goto disable_pmu;
107 	}
108 
109 	/* wait until child signal handler installed */
110 	ASSERT_EQ(read(pipe_c2p[0], buf, 1), 1, "pipe_read");
111 
112 	/* trigger the bpf send_signal */
113 	skel->bss->pid = pid;
114 	skel->bss->sig = SIGUSR1;
115 	skel->bss->signal_thread = signal_thread;
116 
117 	/* notify child that bpf program can send_signal now */
118 	ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");
119 
120 	/* wait for result */
121 	err = read(pipe_c2p[0], buf, 1);
122 	if (!ASSERT_GE(err, 0, "reading pipe"))
123 		goto disable_pmu;
124 	if (!ASSERT_GT(err, 0, "reading pipe error: size 0")) {
125 		err = -1;
126 		goto disable_pmu;
127 	}
128 
129 	ASSERT_EQ(buf[0], '2', "incorrect result");
130 
131 	/* notify child safe to exit */
132 	ASSERT_EQ(write(pipe_p2c[1], buf, 1), 1, "pipe_write");
133 
134 disable_pmu:
135 	close(pmu_fd);
136 destroy_skel:
137 	test_send_signal_kern__destroy(skel);
138 skel_open_load_failure:
139 	close(pipe_c2p[0]);
140 	close(pipe_p2c[1]);
141 	wait(NULL);
142 }
143 
test_send_signal_tracepoint(bool signal_thread)144 static void test_send_signal_tracepoint(bool signal_thread)
145 {
146 	test_send_signal_common(NULL, signal_thread);
147 }
148 
test_send_signal_perf(bool signal_thread)149 static void test_send_signal_perf(bool signal_thread)
150 {
151 	struct perf_event_attr attr = {
152 		.sample_period = 1,
153 		.type = PERF_TYPE_SOFTWARE,
154 		.config = PERF_COUNT_SW_CPU_CLOCK,
155 	};
156 
157 	test_send_signal_common(&attr, signal_thread);
158 }
159 
test_send_signal_nmi(bool signal_thread)160 static void test_send_signal_nmi(bool signal_thread)
161 {
162 	struct perf_event_attr attr = {
163 		.sample_period = 1,
164 		.type = PERF_TYPE_HARDWARE,
165 		.config = PERF_COUNT_HW_CPU_CYCLES,
166 	};
167 	int pmu_fd;
168 
169 	/* Some setups (e.g. virtual machines) might run with hardware
170 	 * perf events disabled. If this is the case, skip this test.
171 	 */
172 	pmu_fd = syscall(__NR_perf_event_open, &attr, 0 /* pid */,
173 			 -1 /* cpu */, -1 /* group_fd */, 0 /* flags */);
174 	if (pmu_fd == -1) {
175 		if (errno == ENOENT) {
176 			printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
177 			       __func__);
178 			test__skip();
179 			return;
180 		}
181 		/* Let the test fail with a more informative message */
182 	} else {
183 		close(pmu_fd);
184 	}
185 
186 	test_send_signal_common(&attr, signal_thread);
187 }
188 
test_send_signal(void)189 void test_send_signal(void)
190 {
191 	if (test__start_subtest("send_signal_tracepoint"))
192 		test_send_signal_tracepoint(false);
193 	if (test__start_subtest("send_signal_perf"))
194 		test_send_signal_perf(false);
195 	if (test__start_subtest("send_signal_nmi"))
196 		test_send_signal_nmi(false);
197 	if (test__start_subtest("send_signal_tracepoint_thread"))
198 		test_send_signal_tracepoint(true);
199 	if (test__start_subtest("send_signal_perf_thread"))
200 		test_send_signal_perf(true);
201 	if (test__start_subtest("send_signal_nmi_thread"))
202 		test_send_signal_nmi(true);
203 }
204