1 files changed, 227 insertions, 0 deletions
diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
new file mode 100644
index 000000000000..1de7478ec189
--- /dev/null
+++ b/tools/perf/tests/sigtrap.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Basic test for sigtrap support.
+ *
+ * Copyright (C) 2021, Google LLC.
+ */
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/string.h>
+#include <pthread.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "cloexec.h"
+#include "debug.h"
+#include "event.h"
+#include "tests.h"
+#include "../perf-sys.h"
+
+#define NUM_THREADS 5
+
+static struct {
+	int tids_want_signal;		/* Which threads still want a signal. */
+	int signal_count;		/* Sanity check number of signals received. */
+	volatile int iterate_on;	/* Variable to set breakpoint on. */
+	siginfo_t first_siginfo;	/* First observed siginfo_t. */
+} ctx;
+
+#define TEST_SIG_DATA (~(unsigned long)(&ctx.iterate_on))
+
+static struct perf_event_attr make_event_attr(void)
+{
+	struct perf_event_attr attr = {
+		.type		= PERF_TYPE_BREAKPOINT,
+		.size		= sizeof(attr),
+		.sample_period	= 1,
+		.disabled	= 1,
+		.bp_addr	= (unsigned long)&ctx.iterate_on,
+		.bp_type	= HW_BREAKPOINT_RW,
+		.bp_len		= HW_BREAKPOINT_LEN_1,
+		.inherit	= 1, /* Children inherit events ... */
+		.inherit_thread = 1, /* ... but only cloned with CLONE_THREAD. */
+		.remove_on_exec = 1, /* Required by sigtrap. */
+		.sigtrap	= 1, /* Request synchronous SIGTRAP on event. */
+		.sig_data	= TEST_SIG_DATA,
+		.exclude_kernel = 1, /* To allow */
+		.exclude_hv     = 1, /* running as !root */
+	};
+	return attr;
+}
+
+#ifdef HAVE_BPF_SKEL
+#include <bpf/btf.h>
+
+static bool attr_has_sigtrap(void)
+{
+	bool ret = false;
+	struct btf *btf;
+	const struct btf_type *t;
+	const struct btf_member *m;
+	const char *name;
+	int i, id;
+
+	btf = btf__load_vmlinux_btf();
+	if (btf == NULL) {
+		/* should be an old kernel */
+		return false;
+	}
+
+	id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
+	if (id < 0)
+		goto out;
+
+	t = btf__type_by_id(btf, id);
+	for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
+		name = btf__name_by_offset(btf, m->name_off);
+		if (!strcmp(name, "sigtrap")) {
+			ret = true;
+			break;
+		}
+	}
+out:
+	btf__free(btf);
+	return ret;
+}
+#else  /* !HAVE_BPF_SKEL */
+static bool attr_has_sigtrap(void)
+{
+	struct perf_event_attr attr = {
+		.type		= PERF_TYPE_SOFTWARE,
+		.config		= PERF_COUNT_SW_DUMMY,
+		.size		= sizeof(attr),
+		.remove_on_exec = 1, /* Required by sigtrap. */
+		.sigtrap	= 1, /* Request synchronous SIGTRAP on event. */
+	};
+	int fd;
+	bool ret = false;
+
+	fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
+	if (fd >= 0) {
+		ret = true;
+		close(fd);
+	}
+
+	return ret;
+}
+#endif  /* HAVE_BPF_SKEL */
+
+static void
+sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
+{
+	if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED))
+		ctx.first_siginfo = *info;
+	__atomic_fetch_sub(&ctx.tids_want_signal, syscall(SYS_gettid), __ATOMIC_RELAXED);
+}
+
+static void *test_thread(void *arg)
+{
+	pthread_barrier_t *barrier = (pthread_barrier_t *)arg;
+	pid_t tid = syscall(SYS_gettid);
+	int i;
+
+	pthread_barrier_wait(barrier);
+
+	__atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
+	for (i = 0; i < ctx.iterate_on - 1; i++)
+		__atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
+
+	return NULL;
+}
+
+static int run_test_threads(pthread_t *threads, pthread_barrier_t *barrier)
+{
+	int i;
+
+	pthread_barrier_wait(barrier);
+	for (i = 0; i < NUM_THREADS; i++)
+		TEST_ASSERT_EQUAL("pthread_join() failed", pthread_join(threads[i], NULL), 0);
+
+	return TEST_OK;
+}
+
+static int run_stress_test(int fd, pthread_t *threads, pthread_barrier_t *barrier)
+{
+	int ret;
+
+	ctx.iterate_on = 3000;
+
+	TEST_ASSERT_EQUAL("misfired signal?", ctx.signal_count, 0);
+	TEST_ASSERT_EQUAL("enable failed", ioctl(fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+	ret = run_test_threads(threads, barrier);
+	TEST_ASSERT_EQUAL("disable failed", ioctl(fd, PERF_EVENT_IOC_DISABLE, 0), 0);
+
+	TEST_ASSERT_EQUAL("unexpected sigtraps", ctx.signal_count, NUM_THREADS * ctx.iterate_on);
+	TEST_ASSERT_EQUAL("missing signals or incorrectly delivered", ctx.tids_want_signal, 0);
+	TEST_ASSERT_VAL("unexpected si_addr", ctx.first_siginfo.si_addr == &ctx.iterate_on);
+#if 0 /* FIXME: enable when libc's signal.h has si_perf_{type,data} */
+	TEST_ASSERT_EQUAL("unexpected si_perf_type", ctx.first_siginfo.si_perf_type,
+			  PERF_TYPE_BREAKPOINT);
+	TEST_ASSERT_EQUAL("unexpected si_perf_data", ctx.first_siginfo.si_perf_data,
+			  TEST_SIG_DATA);
+#endif
+
+	return ret;
+}
+
+static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
+{
+	struct perf_event_attr attr = make_event_attr();
+	struct sigaction action = {};
+	struct sigaction oldact;
+	pthread_t threads[NUM_THREADS];
+	pthread_barrier_t barrier;
+	char sbuf[STRERR_BUFSIZE];
+	int i, fd, ret = TEST_FAIL;
+
+	if (!BP_SIGNAL_IS_SUPPORTED) {
+		pr_debug("Test not supported on this architecture");
+		return TEST_SKIP;
+	}
+
+	pthread_barrier_init(&barrier, NULL, NUM_THREADS + 1);
+
+	action.sa_flags = SA_SIGINFO | SA_NODEFER;
+	action.sa_sigaction = sigtrap_handler;
+	sigemptyset(&action.sa_mask);
+	if (sigaction(SIGTRAP, &action, &oldact)) {
+		pr_debug("FAILED sigaction(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
+		goto out;
+	}
+
+	fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
+	if (fd < 0) {
+		if (attr_has_sigtrap()) {
+			pr_debug("FAILED sys_perf_event_open(): %s\n",
+				 str_error_r(errno, sbuf, sizeof(sbuf)));
+		} else {
+			pr_debug("perf_event_attr doesn't have sigtrap\n");
+			ret = TEST_SKIP;
+		}
+		goto out_restore_sigaction;
+	}
+
+	for (i = 0; i < NUM_THREADS; i++) {
+		if (pthread_create(&threads[i], NULL, test_thread, &barrier)) {
+			pr_debug("FAILED pthread_create(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
+			goto out_close_perf_event;
+		}
+	}
+
+	ret = run_stress_test(fd, threads, &barrier);
+
+out_close_perf_event:
+	close(fd);
+out_restore_sigaction:
+	sigaction(SIGTRAP, &oldact, NULL);
+out:
+	pthread_barrier_destroy(&barrier);
+	return ret;
+}
+
+DEFINE_SUITE("Sigtrap", sigtrap);