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1// SPDX-License-Identifier: GPL-2.02/*3 * Test for perf events with SIGTRAP across all threads.4 *5 * Copyright (C) 2021, Google LLC.6 */7 8#define _GNU_SOURCE9 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 114#define __have_sigval_t 115#define __have_sigevent_t 116#define __siginfo_t_defined17#define __sigval_t_defined18#define __sigevent_t_defined19#define _BITS_SIGINFO_CONSTS_H 120#define _BITS_SIGEVENT_CONSTS_H 121 22#include <stdbool.h>23#include <stddef.h>24#include <stdint.h>25#include <stdio.h>26#include <linux/hw_breakpoint.h>27#include <linux/perf_event.h>28#include <pthread.h>29#include <signal.h>30#include <sys/ioctl.h>31#include <sys/syscall.h>32#include <unistd.h>33 34#include "../kselftest_harness.h"35 36#define NUM_THREADS 537 38/* Data shared between test body, threads, and signal handler. */39static struct {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. */44} ctx;45 46/* Unique value to check si_perf_data is correctly set from perf_event_attr::sig_data. */47#define TEST_SIG_DATA(addr, id) (~(unsigned long)(addr) + id)48 49static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr,50 unsigned long id)51{52 struct perf_event_attr attr = {53 .type = PERF_TYPE_BREAKPOINT,54 .size = sizeof(attr),55 .sample_period = 1,56 .disabled = !enabled,57 .bp_addr = (unsigned long)addr,58 .bp_type = HW_BREAKPOINT_RW,59 .bp_len = HW_BREAKPOINT_LEN_1,60 .inherit = 1, /* Children inherit events ... */61 .inherit_thread = 1, /* ... but only cloned with CLONE_THREAD. */62 .remove_on_exec = 1, /* Required by sigtrap. */63 .sigtrap = 1, /* Request synchronous SIGTRAP on event. */64 .sig_data = TEST_SIG_DATA(addr, id),65 .exclude_kernel = 1, /* To allow */66 .exclude_hv = 1, /* running as !root */67 };68 return attr;69}70 71static void sigtrap_handler(int signum, siginfo_t *info, void *ucontext)72{73 if (info->si_code != TRAP_PERF) {74 fprintf(stderr, "%s: unexpected si_code %d\n", __func__, info->si_code);75 return;76 }77 78 /*79 * The data in siginfo_t we're interested in should all be the same80 * across threads.81 */82 if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED))83 ctx.first_siginfo = *info;84 __atomic_fetch_sub(&ctx.tids_want_signal, syscall(__NR_gettid), __ATOMIC_RELAXED);85}86 87static void *test_thread(void *arg)88{89 pthread_barrier_t *barrier = (pthread_barrier_t *)arg;90 pid_t tid = syscall(__NR_gettid);91 int iter;92 int i;93 94 pthread_barrier_wait(barrier);95 96 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);97 iter = ctx.iterate_on; /* read */98 if (iter >= 0) {99 for (i = 0; i < iter - 1; i++) {100 __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);101 ctx.iterate_on = iter; /* idempotent write */102 }103 } else {104 while (ctx.iterate_on);105 }106 107 return NULL;108}109 110FIXTURE(sigtrap_threads)111{112 struct sigaction oldact;113 pthread_t threads[NUM_THREADS];114 pthread_barrier_t barrier;115 int fd;116};117 118FIXTURE_SETUP(sigtrap_threads)119{120 struct perf_event_attr attr = make_event_attr(false, &ctx.iterate_on, 0);121 struct sigaction action = {};122 int i;123 124 memset(&ctx, 0, sizeof(ctx));125 126 /* Initialize sigtrap handler. */127 action.sa_flags = SA_SIGINFO | SA_NODEFER;128 action.sa_sigaction = sigtrap_handler;129 sigemptyset(&action.sa_mask);130 ASSERT_EQ(sigaction(SIGTRAP, &action, &self->oldact), 0);131 132 /* Initialize perf event. */133 self->fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, PERF_FLAG_FD_CLOEXEC);134 ASSERT_NE(self->fd, -1);135 136 /* Spawn threads inheriting perf event. */137 pthread_barrier_init(&self->barrier, NULL, NUM_THREADS + 1);138 for (i = 0; i < NUM_THREADS; i++)139 ASSERT_EQ(pthread_create(&self->threads[i], NULL, test_thread, &self->barrier), 0);140}141 142FIXTURE_TEARDOWN(sigtrap_threads)143{144 pthread_barrier_destroy(&self->barrier);145 close(self->fd);146 sigaction(SIGTRAP, &self->oldact, NULL);147}148 149static void run_test_threads(struct __test_metadata *_metadata,150 FIXTURE_DATA(sigtrap_threads) *self)151{152 int i;153 154 pthread_barrier_wait(&self->barrier);155 for (i = 0; i < NUM_THREADS; i++)156 ASSERT_EQ(pthread_join(self->threads[i], NULL), 0);157}158 159TEST_F(sigtrap_threads, remain_disabled)160{161 run_test_threads(_metadata, self);162 EXPECT_EQ(ctx.signal_count, 0);163 EXPECT_NE(ctx.tids_want_signal, 0);164}165 166TEST_F(sigtrap_threads, enable_event)167{168 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);169 run_test_threads(_metadata, self);170 171 EXPECT_EQ(ctx.signal_count, NUM_THREADS);172 EXPECT_EQ(ctx.tids_want_signal, 0);173 EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);174 EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);175 EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));176 177 /* Check enabled for parent. */178 ctx.iterate_on = 0;179 EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);180}181 182/* Test that modification propagates to all inherited events. */183TEST_F(sigtrap_threads, modify_and_enable_event)184{185 struct perf_event_attr new_attr = make_event_attr(true, &ctx.iterate_on, 42);186 187 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &new_attr), 0);188 run_test_threads(_metadata, self);189 190 EXPECT_EQ(ctx.signal_count, NUM_THREADS);191 EXPECT_EQ(ctx.tids_want_signal, 0);192 EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);193 EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);194 EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 42));195 196 /* Check enabled for parent. */197 ctx.iterate_on = 0;198 EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);199}200 201/* Stress test event + signal handling. */202TEST_F(sigtrap_threads, signal_stress)203{204 ctx.iterate_on = 3000;205 206 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);207 run_test_threads(_metadata, self);208 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);209 210 EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);211 EXPECT_EQ(ctx.tids_want_signal, 0);212 EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);213 EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);214 EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));215}216 217TEST_F(sigtrap_threads, signal_stress_with_disable)218{219 const int target_count = NUM_THREADS * 3000;220 int i;221 222 ctx.iterate_on = -1;223 224 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);225 pthread_barrier_wait(&self->barrier);226 while (__atomic_load_n(&ctx.signal_count, __ATOMIC_RELAXED) < target_count) {227 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);228 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);229 }230 ctx.iterate_on = 0;231 for (i = 0; i < NUM_THREADS; i++)232 ASSERT_EQ(pthread_join(self->threads[i], NULL), 0);233 EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);234 235 EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);236 EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);237 EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));238}239 240TEST_HARNESS_MAIN241