tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Basic test for sigtrap support.
4 *
5 * Copyright (C) 2021, Google LLC.
6 */
7
8#include <errno.h>
9#include <stdint.h>
10#include <stdlib.h>
11#include <linux/hw_breakpoint.h>
12#include <linux/string.h>
13#include <pthread.h>
14#include <signal.h>
15#include <sys/ioctl.h>
16#include <sys/syscall.h>
17#include <unistd.h>
18
19#include "cloexec.h"
20#include "debug.h"
21#include "event.h"
22#include "tests.h"
23#include "../perf-sys.h"
24
25#define NUM_THREADS 5
26
27static struct {
28 int tids_want_signal; /* Which threads still want a signal. */
29 int signal_count; /* Sanity check number of signals received. */
30 volatile int iterate_on; /* Variable to set breakpoint on. */
31 siginfo_t first_siginfo; /* First observed siginfo_t. */
32} ctx;
33
34#define TEST_SIG_DATA (~(unsigned long)(&ctx.iterate_on))
35
36static struct perf_event_attr make_event_attr(void)
37{
38 struct perf_event_attr attr = {
39 .type = PERF_TYPE_BREAKPOINT,
40 .size = sizeof(attr),
41 .sample_period = 1,
42 .disabled = 1,
43 .bp_addr = (unsigned long)&ctx.iterate_on,
44 .bp_type = HW_BREAKPOINT_RW,
45 .bp_len = HW_BREAKPOINT_LEN_1,
46 .inherit = 1, /* Children inherit events ... */
47 .inherit_thread = 1, /* ... but only cloned with CLONE_THREAD. */
48 .remove_on_exec = 1, /* Required by sigtrap. */
49 .sigtrap = 1, /* Request synchronous SIGTRAP on event. */
50 .sig_data = TEST_SIG_DATA,
51 .exclude_kernel = 1, /* To allow */
52 .exclude_hv = 1, /* running as !root */
53 };
54 return attr;
55}
56
57static void
58sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
59{
60 if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED))
61 ctx.first_siginfo = *info;
62 __atomic_fetch_sub(&ctx.tids_want_signal, syscall(SYS_gettid), __ATOMIC_RELAXED);
63}
64
65static void *test_thread(void *arg)
66{
67 pthread_barrier_t *barrier = (pthread_barrier_t *)arg;
68 pid_t tid = syscall(SYS_gettid);
69 int i;
70
71 pthread_barrier_wait(barrier);
72
73 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
74 for (i = 0; i < ctx.iterate_on - 1; i++)
75 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
76
77 return NULL;
78}
79
80static int run_test_threads(pthread_t *threads, pthread_barrier_t *barrier)
81{
82 int i;
83
84 pthread_barrier_wait(barrier);
85 for (i = 0; i < NUM_THREADS; i++)
86 TEST_ASSERT_EQUAL("pthread_join() failed", pthread_join(threads[i], NULL), 0);
87
88 return TEST_OK;
89}
90
91static int run_stress_test(int fd, pthread_t *threads, pthread_barrier_t *barrier)
92{
93 int ret;
94
95 ctx.iterate_on = 3000;
96
97 TEST_ASSERT_EQUAL("misfired signal?", ctx.signal_count, 0);
98 TEST_ASSERT_EQUAL("enable failed", ioctl(fd, PERF_EVENT_IOC_ENABLE, 0), 0);
99 ret = run_test_threads(threads, barrier);
100 TEST_ASSERT_EQUAL("disable failed", ioctl(fd, PERF_EVENT_IOC_DISABLE, 0), 0);
101
102 TEST_ASSERT_EQUAL("unexpected sigtraps", ctx.signal_count, NUM_THREADS * ctx.iterate_on);
103 TEST_ASSERT_EQUAL("missing signals or incorrectly delivered", ctx.tids_want_signal, 0);
104 TEST_ASSERT_VAL("unexpected si_addr", ctx.first_siginfo.si_addr == &ctx.iterate_on);
105#if 0 /* FIXME: enable when libc's signal.h has si_perf_{type,data} */
106 TEST_ASSERT_EQUAL("unexpected si_perf_type", ctx.first_siginfo.si_perf_type,
107 PERF_TYPE_BREAKPOINT);
108 TEST_ASSERT_EQUAL("unexpected si_perf_data", ctx.first_siginfo.si_perf_data,
109 TEST_SIG_DATA);
110#endif
111
112 return ret;
113}
114
115static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
116{
117 struct perf_event_attr attr = make_event_attr();
118 struct sigaction action = {};
119 struct sigaction oldact;
120 pthread_t threads[NUM_THREADS];
121 pthread_barrier_t barrier;
122 char sbuf[STRERR_BUFSIZE];
123 int i, fd, ret = TEST_FAIL;
124
125 if (!BP_SIGNAL_IS_SUPPORTED) {
126 pr_debug("Test not supported on this architecture");
127 return TEST_SKIP;
128 }
129
130 pthread_barrier_init(&barrier, NULL, NUM_THREADS + 1);
131
132 action.sa_flags = SA_SIGINFO | SA_NODEFER;
133 action.sa_sigaction = sigtrap_handler;
134 sigemptyset(&action.sa_mask);
135 if (sigaction(SIGTRAP, &action, &oldact)) {
136 pr_debug("FAILED sigaction(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
137 goto out;
138 }
139
140 fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
141 if (fd < 0) {
142 pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
143 goto out_restore_sigaction;
144 }
145
146 for (i = 0; i < NUM_THREADS; i++) {
147 if (pthread_create(&threads[i], NULL, test_thread, &barrier)) {
148 pr_debug("FAILED pthread_create(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
149 goto out_close_perf_event;
150 }
151 }
152
153 ret = run_stress_test(fd, threads, &barrier);
154
155out_close_perf_event:
156 close(fd);
157out_restore_sigaction:
158 sigaction(SIGTRAP, &oldact, NULL);
159out:
160 pthread_barrier_destroy(&barrier);
161 return ret;
162}
163
164DEFINE_SUITE("Sigtrap", sigtrap);