1 // SPDX-License-Identifier: GPL-2.0
3 * Test for perf events with SIGTRAP across all threads.
5 * Copyright (C) 2021, Google LLC.
10 /* We need the latest siginfo from the kernel repo. */
11 #include <sys/types.h>
12 #include <asm/siginfo.h>
13 #define __have_siginfo_t 1
14 #define __have_sigval_t 1
15 #define __have_sigevent_t 1
16 #define __siginfo_t_defined
17 #define __sigval_t_defined
18 #define __sigevent_t_defined
19 #define _BITS_SIGINFO_CONSTS_H 1
20 #define _BITS_SIGEVENT_CONSTS_H 1
26 #include <linux/hw_breakpoint.h>
27 #include <linux/perf_event.h>
30 #include <sys/ioctl.h>
31 #include <sys/syscall.h>
34 #include "../kselftest_harness.h"
38 /* Data shared between test body, threads, and signal handler. */
40 int tids_want_signal; /* Which threads still want a signal. */
41 int signal_count; /* Sanity check number of signals received. */
42 volatile int iterate_on; /* Variable to set breakpoint on. */
43 siginfo_t first_siginfo; /* First observed siginfo_t. */
46 /* Unique value to check si_perf is correctly set from perf_event_attr::sig_data. */
47 #define TEST_SIG_DATA(addr) (~(unsigned long)(addr))
49 static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr)
51 struct perf_event_attr attr = {
52 .type = PERF_TYPE_BREAKPOINT,
56 .bp_addr = (unsigned long)addr,
57 .bp_type = HW_BREAKPOINT_RW,
58 .bp_len = HW_BREAKPOINT_LEN_1,
59 .inherit = 1, /* Children inherit events ... */
60 .inherit_thread = 1, /* ... but only cloned with CLONE_THREAD. */
61 .remove_on_exec = 1, /* Required by sigtrap. */
62 .sigtrap = 1, /* Request synchronous SIGTRAP on event. */
63 .sig_data = TEST_SIG_DATA(addr),
68 static void sigtrap_handler(int signum, siginfo_t *info, void *ucontext)
70 if (info->si_code != TRAP_PERF) {
71 fprintf(stderr, "%s: unexpected si_code %d\n", __func__, info->si_code);
76 * The data in siginfo_t we're interested in should all be the same
79 if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED))
80 ctx.first_siginfo = *info;
81 __atomic_fetch_sub(&ctx.tids_want_signal, syscall(__NR_gettid), __ATOMIC_RELAXED);
84 static void *test_thread(void *arg)
86 pthread_barrier_t *barrier = (pthread_barrier_t *)arg;
87 pid_t tid = syscall(__NR_gettid);
91 pthread_barrier_wait(barrier);
93 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
94 iter = ctx.iterate_on; /* read */
95 for (i = 0; i < iter - 1; i++) {
96 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
97 ctx.iterate_on = iter; /* idempotent write */
103 FIXTURE(sigtrap_threads)
105 struct sigaction oldact;
106 pthread_t threads[NUM_THREADS];
107 pthread_barrier_t barrier;
111 FIXTURE_SETUP(sigtrap_threads)
113 struct perf_event_attr attr = make_event_attr(false, &ctx.iterate_on);
114 struct sigaction action = {};
117 memset(&ctx, 0, sizeof(ctx));
119 /* Initialize sigtrap handler. */
120 action.sa_flags = SA_SIGINFO | SA_NODEFER;
121 action.sa_sigaction = sigtrap_handler;
122 sigemptyset(&action.sa_mask);
123 ASSERT_EQ(sigaction(SIGTRAP, &action, &self->oldact), 0);
125 /* Initialize perf event. */
126 self->fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, PERF_FLAG_FD_CLOEXEC);
127 ASSERT_NE(self->fd, -1);
129 /* Spawn threads inheriting perf event. */
130 pthread_barrier_init(&self->barrier, NULL, NUM_THREADS + 1);
131 for (i = 0; i < NUM_THREADS; i++)
132 ASSERT_EQ(pthread_create(&self->threads[i], NULL, test_thread, &self->barrier), 0);
135 FIXTURE_TEARDOWN(sigtrap_threads)
137 pthread_barrier_destroy(&self->barrier);
139 sigaction(SIGTRAP, &self->oldact, NULL);
142 static void run_test_threads(struct __test_metadata *_metadata,
143 FIXTURE_DATA(sigtrap_threads) *self)
147 pthread_barrier_wait(&self->barrier);
148 for (i = 0; i < NUM_THREADS; i++)
149 ASSERT_EQ(pthread_join(self->threads[i], NULL), 0);
152 TEST_F(sigtrap_threads, remain_disabled)
154 run_test_threads(_metadata, self);
155 EXPECT_EQ(ctx.signal_count, 0);
156 EXPECT_NE(ctx.tids_want_signal, 0);
159 TEST_F(sigtrap_threads, enable_event)
161 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
162 run_test_threads(_metadata, self);
164 EXPECT_EQ(ctx.signal_count, NUM_THREADS);
165 EXPECT_EQ(ctx.tids_want_signal, 0);
166 EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
167 EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
168 EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
170 /* Check enabled for parent. */
172 EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);
175 /* Test that modification propagates to all inherited events. */
176 TEST_F(sigtrap_threads, modify_and_enable_event)
178 struct perf_event_attr new_attr = make_event_attr(true, &ctx.iterate_on);
180 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &new_attr), 0);
181 run_test_threads(_metadata, self);
183 EXPECT_EQ(ctx.signal_count, NUM_THREADS);
184 EXPECT_EQ(ctx.tids_want_signal, 0);
185 EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
186 EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
187 EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
189 /* Check enabled for parent. */
191 EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);
194 /* Stress test event + signal handling. */
195 TEST_F(sigtrap_threads, signal_stress)
197 ctx.iterate_on = 3000;
199 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
200 run_test_threads(_metadata, self);
201 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);
203 EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
204 EXPECT_EQ(ctx.tids_want_signal, 0);
205 EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
206 EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
207 EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));