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23488ec668
Add a SIGTRAP stress test that exercises repeatedly enabling/disabling an event while it concurrently keeps firing. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/Y0E3uG7jOywn7vy3@elver.google.com/
241 lines
6.9 KiB
C
241 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Test for perf events with SIGTRAP across all threads.
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*
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* Copyright (C) 2021, Google LLC.
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*/
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#define _GNU_SOURCE
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/* We need the latest siginfo from the kernel repo. */
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#include <sys/types.h>
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#include <asm/siginfo.h>
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#define __have_siginfo_t 1
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#define __have_sigval_t 1
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#define __have_sigevent_t 1
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#define __siginfo_t_defined
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#define __sigval_t_defined
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#define __sigevent_t_defined
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#define _BITS_SIGINFO_CONSTS_H 1
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#define _BITS_SIGEVENT_CONSTS_H 1
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <linux/hw_breakpoint.h>
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#include <linux/perf_event.h>
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#include <pthread.h>
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#include <signal.h>
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#include <sys/ioctl.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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#include "../kselftest_harness.h"
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#define NUM_THREADS 5
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/* Data shared between test body, threads, and signal handler. */
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static struct {
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int tids_want_signal; /* Which threads still want a signal. */
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int signal_count; /* Sanity check number of signals received. */
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volatile int iterate_on; /* Variable to set breakpoint on. */
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siginfo_t first_siginfo; /* First observed siginfo_t. */
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} ctx;
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/* Unique value to check si_perf_data is correctly set from perf_event_attr::sig_data. */
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#define TEST_SIG_DATA(addr, id) (~(unsigned long)(addr) + id)
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static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr,
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unsigned long id)
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{
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struct perf_event_attr attr = {
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.type = PERF_TYPE_BREAKPOINT,
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.size = sizeof(attr),
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.sample_period = 1,
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.disabled = !enabled,
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.bp_addr = (unsigned long)addr,
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.bp_type = HW_BREAKPOINT_RW,
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.bp_len = HW_BREAKPOINT_LEN_1,
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.inherit = 1, /* Children inherit events ... */
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.inherit_thread = 1, /* ... but only cloned with CLONE_THREAD. */
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.remove_on_exec = 1, /* Required by sigtrap. */
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.sigtrap = 1, /* Request synchronous SIGTRAP on event. */
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.sig_data = TEST_SIG_DATA(addr, id),
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.exclude_kernel = 1, /* To allow */
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.exclude_hv = 1, /* running as !root */
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};
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return attr;
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}
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static void sigtrap_handler(int signum, siginfo_t *info, void *ucontext)
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{
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if (info->si_code != TRAP_PERF) {
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fprintf(stderr, "%s: unexpected si_code %d\n", __func__, info->si_code);
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return;
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}
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/*
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* The data in siginfo_t we're interested in should all be the same
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* across threads.
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*/
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if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED))
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ctx.first_siginfo = *info;
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__atomic_fetch_sub(&ctx.tids_want_signal, syscall(__NR_gettid), __ATOMIC_RELAXED);
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}
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static void *test_thread(void *arg)
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{
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pthread_barrier_t *barrier = (pthread_barrier_t *)arg;
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pid_t tid = syscall(__NR_gettid);
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int iter;
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int i;
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pthread_barrier_wait(barrier);
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__atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
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iter = ctx.iterate_on; /* read */
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if (iter >= 0) {
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for (i = 0; i < iter - 1; i++) {
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__atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
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ctx.iterate_on = iter; /* idempotent write */
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}
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} else {
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while (ctx.iterate_on);
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}
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return NULL;
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}
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FIXTURE(sigtrap_threads)
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{
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struct sigaction oldact;
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pthread_t threads[NUM_THREADS];
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pthread_barrier_t barrier;
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int fd;
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};
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FIXTURE_SETUP(sigtrap_threads)
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{
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struct perf_event_attr attr = make_event_attr(false, &ctx.iterate_on, 0);
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struct sigaction action = {};
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int i;
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memset(&ctx, 0, sizeof(ctx));
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/* Initialize sigtrap handler. */
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action.sa_flags = SA_SIGINFO | SA_NODEFER;
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action.sa_sigaction = sigtrap_handler;
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sigemptyset(&action.sa_mask);
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ASSERT_EQ(sigaction(SIGTRAP, &action, &self->oldact), 0);
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/* Initialize perf event. */
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self->fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, PERF_FLAG_FD_CLOEXEC);
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ASSERT_NE(self->fd, -1);
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/* Spawn threads inheriting perf event. */
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pthread_barrier_init(&self->barrier, NULL, NUM_THREADS + 1);
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for (i = 0; i < NUM_THREADS; i++)
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ASSERT_EQ(pthread_create(&self->threads[i], NULL, test_thread, &self->barrier), 0);
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}
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FIXTURE_TEARDOWN(sigtrap_threads)
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{
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pthread_barrier_destroy(&self->barrier);
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close(self->fd);
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sigaction(SIGTRAP, &self->oldact, NULL);
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}
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static void run_test_threads(struct __test_metadata *_metadata,
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FIXTURE_DATA(sigtrap_threads) *self)
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{
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int i;
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pthread_barrier_wait(&self->barrier);
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for (i = 0; i < NUM_THREADS; i++)
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ASSERT_EQ(pthread_join(self->threads[i], NULL), 0);
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}
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TEST_F(sigtrap_threads, remain_disabled)
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{
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run_test_threads(_metadata, self);
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EXPECT_EQ(ctx.signal_count, 0);
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EXPECT_NE(ctx.tids_want_signal, 0);
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}
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TEST_F(sigtrap_threads, enable_event)
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{
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
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run_test_threads(_metadata, self);
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EXPECT_EQ(ctx.signal_count, NUM_THREADS);
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EXPECT_EQ(ctx.tids_want_signal, 0);
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EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
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EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
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EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));
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/* Check enabled for parent. */
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ctx.iterate_on = 0;
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EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);
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}
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/* Test that modification propagates to all inherited events. */
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TEST_F(sigtrap_threads, modify_and_enable_event)
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{
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struct perf_event_attr new_attr = make_event_attr(true, &ctx.iterate_on, 42);
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &new_attr), 0);
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run_test_threads(_metadata, self);
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EXPECT_EQ(ctx.signal_count, NUM_THREADS);
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EXPECT_EQ(ctx.tids_want_signal, 0);
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EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
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EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
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EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 42));
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/* Check enabled for parent. */
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ctx.iterate_on = 0;
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EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);
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}
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/* Stress test event + signal handling. */
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TEST_F(sigtrap_threads, signal_stress)
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{
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ctx.iterate_on = 3000;
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
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run_test_threads(_metadata, self);
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);
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EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
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EXPECT_EQ(ctx.tids_want_signal, 0);
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EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
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EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
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EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));
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}
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TEST_F(sigtrap_threads, signal_stress_with_disable)
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{
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const int target_count = NUM_THREADS * 3000;
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int i;
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ctx.iterate_on = -1;
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
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pthread_barrier_wait(&self->barrier);
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while (__atomic_load_n(&ctx.signal_count, __ATOMIC_RELAXED) < target_count) {
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
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}
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ctx.iterate_on = 0;
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for (i = 0; i < NUM_THREADS; i++)
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ASSERT_EQ(pthread_join(self->threads[i], NULL), 0);
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EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);
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EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
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EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
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EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));
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}
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TEST_HARNESS_MAIN
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