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 27 static 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 36 static 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 57 #ifdef HAVE_BPF_SKEL 58 #include <bpf/btf.h> 59 60 static bool attr_has_sigtrap(void) 61 { 62 bool ret = false; 63 struct btf *btf; 64 const struct btf_type *t; 65 const struct btf_member *m; 66 const char *name; 67 int i, id; 68 69 btf = btf__load_vmlinux_btf(); 70 if (btf == NULL) { 71 /* should be an old kernel */ 72 return false; 73 } 74 75 id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT); 76 if (id < 0) 77 goto out; 78 79 t = btf__type_by_id(btf, id); 80 for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) { 81 name = btf__name_by_offset(btf, m->name_off); 82 if (!strcmp(name, "sigtrap")) { 83 ret = true; 84 break; 85 } 86 } 87 out: 88 btf__free(btf); 89 return ret; 90 } 91 #else /* !HAVE_BPF_SKEL */ 92 static bool attr_has_sigtrap(void) 93 { 94 struct perf_event_attr attr = { 95 .type = PERF_TYPE_SOFTWARE, 96 .config = PERF_COUNT_SW_DUMMY, 97 .size = sizeof(attr), 98 .remove_on_exec = 1, /* Required by sigtrap. */ 99 .sigtrap = 1, /* Request synchronous SIGTRAP on event. */ 100 }; 101 int fd; 102 bool ret = false; 103 104 fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag()); 105 if (fd >= 0) { 106 ret = true; 107 close(fd); 108 } 109 110 return ret; 111 } 112 #endif /* HAVE_BPF_SKEL */ 113 114 static void 115 sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused) 116 { 117 if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED)) 118 ctx.first_siginfo = *info; 119 __atomic_fetch_sub(&ctx.tids_want_signal, syscall(SYS_gettid), __ATOMIC_RELAXED); 120 } 121 122 static void *test_thread(void *arg) 123 { 124 pthread_barrier_t *barrier = (pthread_barrier_t *)arg; 125 pid_t tid = syscall(SYS_gettid); 126 int i; 127 128 pthread_barrier_wait(barrier); 129 130 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED); 131 for (i = 0; i < ctx.iterate_on - 1; i++) 132 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED); 133 134 return NULL; 135 } 136 137 static int run_test_threads(pthread_t *threads, pthread_barrier_t *barrier) 138 { 139 int i; 140 141 pthread_barrier_wait(barrier); 142 for (i = 0; i < NUM_THREADS; i++) 143 TEST_ASSERT_EQUAL("pthread_join() failed", pthread_join(threads[i], NULL), 0); 144 145 return TEST_OK; 146 } 147 148 static int run_stress_test(int fd, pthread_t *threads, pthread_barrier_t *barrier) 149 { 150 int ret; 151 152 ctx.iterate_on = 3000; 153 154 TEST_ASSERT_EQUAL("misfired signal?", ctx.signal_count, 0); 155 TEST_ASSERT_EQUAL("enable failed", ioctl(fd, PERF_EVENT_IOC_ENABLE, 0), 0); 156 ret = run_test_threads(threads, barrier); 157 TEST_ASSERT_EQUAL("disable failed", ioctl(fd, PERF_EVENT_IOC_DISABLE, 0), 0); 158 159 TEST_ASSERT_EQUAL("unexpected sigtraps", ctx.signal_count, NUM_THREADS * ctx.iterate_on); 160 TEST_ASSERT_EQUAL("missing signals or incorrectly delivered", ctx.tids_want_signal, 0); 161 TEST_ASSERT_VAL("unexpected si_addr", ctx.first_siginfo.si_addr == &ctx.iterate_on); 162 #if 0 /* FIXME: enable when libc's signal.h has si_perf_{type,data} */ 163 TEST_ASSERT_EQUAL("unexpected si_perf_type", ctx.first_siginfo.si_perf_type, 164 PERF_TYPE_BREAKPOINT); 165 TEST_ASSERT_EQUAL("unexpected si_perf_data", ctx.first_siginfo.si_perf_data, 166 TEST_SIG_DATA); 167 #endif 168 169 return ret; 170 } 171 172 static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __maybe_unused) 173 { 174 struct perf_event_attr attr = make_event_attr(); 175 struct sigaction action = {}; 176 struct sigaction oldact; 177 pthread_t threads[NUM_THREADS]; 178 pthread_barrier_t barrier; 179 char sbuf[STRERR_BUFSIZE]; 180 int i, fd, ret = TEST_FAIL; 181 182 if (!BP_SIGNAL_IS_SUPPORTED) { 183 pr_debug("Test not supported on this architecture"); 184 return TEST_SKIP; 185 } 186 187 pthread_barrier_init(&barrier, NULL, NUM_THREADS + 1); 188 189 action.sa_flags = SA_SIGINFO | SA_NODEFER; 190 action.sa_sigaction = sigtrap_handler; 191 sigemptyset(&action.sa_mask); 192 if (sigaction(SIGTRAP, &action, &oldact)) { 193 pr_debug("FAILED sigaction(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf))); 194 goto out; 195 } 196 197 fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag()); 198 if (fd < 0) { 199 if (attr_has_sigtrap()) { 200 pr_debug("FAILED sys_perf_event_open(): %s\n", 201 str_error_r(errno, sbuf, sizeof(sbuf))); 202 } else { 203 pr_debug("perf_event_attr doesn't have sigtrap\n"); 204 ret = TEST_SKIP; 205 } 206 goto out_restore_sigaction; 207 } 208 209 for (i = 0; i < NUM_THREADS; i++) { 210 if (pthread_create(&threads[i], NULL, test_thread, &barrier)) { 211 pr_debug("FAILED pthread_create(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf))); 212 goto out_close_perf_event; 213 } 214 } 215 216 ret = run_stress_test(fd, threads, &barrier); 217 218 out_close_perf_event: 219 close(fd); 220 out_restore_sigaction: 221 sigaction(SIGTRAP, &oldact, NULL); 222 out: 223 pthread_barrier_destroy(&barrier); 224 return ret; 225 } 226 227 DEFINE_SUITE("Sigtrap", sigtrap); 228