sigtrap.c (4739B)
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);