[V12,4/4] tools/testing/selftests/bpf: Add self-tests for new helper.

diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 54a50699bbfd..19c03ba066b1 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -233,6 +233,9 @@  static int (*bpf_send_signal)(unsigned sig) = (void *)BPF_FUNC_send_signal;
 static long long (*bpf_tcp_gen_syncookie)(struct bpf_sock *sk, void *ip,
 					  int ip_len, void *tcp, int tcp_len) =
 	(void *) BPF_FUNC_tcp_gen_syncookie;
+static unsigned long long (*bpf_get_ns_current_pid_tgid)(__u64 dev, __u64 inum) =
+	(void *) BPF_FUNC_get_ns_current_pid_tgid;
+
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions
diff --git a/tools/testing/selftests/bpf/prog_tests/get_ns_current_pid_tgid.c b/tools/testing/selftests/bpf/prog_tests/get_ns_current_pid_tgid.c
new file mode 100644
index 000000000000..4d8ec524d373
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/get_ns_current_pid_tgid.c
@@ -0,0 +1,85 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Carlos Neira cneirabustos@gmail.com */
+#include <test_progs.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+void test_get_ns_current_pid_tgid(void)
+{
+	const char *probe_name = "syscalls/sys_enter_nanosleep";
+	const char *file = "get_ns_current_pid_tgid_kern.o";
+	int ns_data_map_fd, duration = 0;
+	struct perf_event_attr attr = {};
+	int err, efd, prog_fd, pmu_fd;
+	__u64 ino, dev, id, nspid;
+	struct bpf_object *obj;
+	struct stat st;
+	__u32 key = 0;
+	char buf[256];
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
+	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
+		return;
+
+	ns_data_map_fd = bpf_find_map(__func__, obj, "ns_data_map");
+	if (CHECK_FAIL(ns_data_map_fd < 0))
+		goto close_prog;
+
+	pid_t tid = syscall(SYS_gettid);
+	pid_t pid = getpid();
+
+	id = (__u64) tid << 32 | pid;
+	bpf_map_update_elem(ns_data_map_fd, &key, &id, 0);
+
+	if (stat("/proc/self/ns/pid", &st))
+		goto close_prog;
+
+	dev = st.st_dev;
+	ino = st.st_ino;
+	key = 1;
+	bpf_map_update_elem(ns_data_map_fd, &key, &dev, 0);
+	key = 2;
+	bpf_map_update_elem(ns_data_map_fd, &key, &ino, 0);
+
+	snprintf(buf, sizeof(buf),
+		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
+	efd = open(buf, O_RDONLY, 0);
+	read(efd, buf, sizeof(buf));
+	close(efd);
+	attr.config = strtol(buf, NULL, 0);
+	attr.type = PERF_TYPE_TRACEPOINT;
+	attr.sample_type = PERF_SAMPLE_RAW;
+	attr.sample_period = 1;
+	attr.wakeup_events = 1;
+
+	pmu_fd = syscall(__NR_perf_event_open, &attr, getpid(), -1, -1, 0);
+	if (CHECK_FAIL(pmu_fd < 0))
+		goto cleanup;
+
+	err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
+	if (CHECK_FAIL(err))
+		goto cleanup;
+
+	err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
+	if (CHECK_FAIL(err))
+		goto cleanup;
+
+	/* trigger some syscalls */
+	sleep(1);
+	key = 3;
+	err = bpf_map_lookup_elem(ns_data_map_fd, &key, &nspid);
+	if (CHECK_FAIL(err))
+		goto cleanup;
+
+	if (CHECK(id != nspid, "Compare user pid/tgid %llu vs. bpf pid/tgid %llu",
+		  "Userspace pid/tgid %llu EBPF pid/tgid %llu\n", id, nspid))
+		goto cleanup;
+
+cleanup:
+	close(pmu_fd);
+close_prog:
+	bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/progs/get_ns_current_pid_tgid_kern.c b/tools/testing/selftests/bpf/progs/get_ns_current_pid_tgid_kern.c
new file mode 100644
index 000000000000..00a325e85e8c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/get_ns_current_pid_tgid_kern.c
@@ -0,0 +1,47 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Carlos Neira cneirabustos@gmail.com */
+
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 4);
+	__type(key, __u32);
+	__type(value, __u64);
+} ns_data_map SEC(".maps");
+
+
+SEC("tracepoint/syscalls/sys_enter_nanosleep")
+int trace(void *ctx)
+{
+	__u64 *val, *inum, *dev, nspid, *expected_pid;
+	__u32 key = 1;
+
+	dev = bpf_map_lookup_elem(&ns_data_map, &key);
+	if (!dev)
+		return 0;
+	key = 2;
+	inum = bpf_map_lookup_elem(&ns_data_map, &key);
+
+	if (!inum)
+		return 0;
+
+	nspid =  bpf_get_ns_current_pid_tgid(*dev, *inum);
+	key = 0;
+	expected_pid = bpf_map_lookup_elem(&ns_data_map, &key);
+
+	if (!expected_pid || *expected_pid != nspid)
+		return 0;
+
+	key = 3;
+	val = bpf_map_lookup_elem(&ns_data_map, &key);
+
+	if (val)
+		*val = nspid;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1;