[PATCH bpf-next 3/5] selftests/bpf: add selftest for BPF_PROG_TYPE_USER

[Song Liu <songliubraving@fb.com>]

This test checks the correctness of BPF_PROG_TYPE_USER program, including:
running on the right cpu, passing in correct args, returning retval, and
being able to call bpf_get_stack|stackid.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
 .../selftests/bpf/prog_tests/user_prog.c      | 52 +++++++++++++++++
 tools/testing/selftests/bpf/progs/user_prog.c | 56 +++++++++++++++++++
 2 files changed, 108 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/user_prog.c
 create mode 100644 tools/testing/selftests/bpf/progs/user_prog.c

diff --git a/tools/testing/selftests/bpf/prog_tests/user_prog.c b/tools/testing/selftests/bpf/prog_tests/user_prog.c
new file mode 100644
index 0000000000000..416707b3bff01
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/user_prog.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include <test_progs.h>
+#include "user_prog.skel.h"
+
+static int duration;
+
+void test_user_prog(void)
+{
+	struct bpf_user_prog_args args = {{0, 1, 2, 3, 4}};
+	struct bpf_prog_test_run_attr attr = {};
+	struct user_prog *skel;
+	int i, numcpu, ret;
+
+	skel = user_prog__open_and_load();
+
+	if (CHECK(!skel, "user_prog__open_and_load",
+		  "skeleton open_and_laod failed\n"))
+		return;
+
+	numcpu = libbpf_num_possible_cpus();
+
+	attr.prog_fd = bpf_program__fd(skel->progs.user_func);
+	attr.data_size_in = sizeof(args);
+	attr.data_in = &args;
+
+	/* start from -1, so we test cpu_plus == 0 */
+	for (i = -1; i < numcpu; i++) {
+		args.args[0] = i + 1;
+		attr.cpu_plus = i + 1;
+		ret = bpf_prog_test_run_xattr(&attr);
+		CHECK(ret, "bpf_prog_test_run_xattr", "returns error\n");
+
+		/* skip two tests for i == -1 */
+		if (i == -1)
+			continue;
+		CHECK(attr.retval != i + 2, "bpf_prog_test_run_xattr",
+		      "doesn't get expected retval\n");
+		CHECK(skel->data->sum != 11 + i, "user_prog_args_test",
+		      "sum of args doesn't match\n");
+	}
+
+	CHECK(skel->data->cpu_match == 0, "cpu_match_test", "failed\n");
+	CHECK(skel->bss->get_stack_success != numcpu + 1, "test_bpf_get_stack",
+	      "failed on %d cores\n", numcpu - skel->bss->get_stack_success);
+	CHECK(skel->bss->get_stackid_success != numcpu + 1,
+	      "test_bpf_get_stackid",
+	      "failed on %d cores\n",
+	      numcpu + 1 - skel->bss->get_stackid_success);
+
+	user_prog__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/user_prog.c b/tools/testing/selftests/bpf/progs/user_prog.c
new file mode 100644
index 0000000000000..cf320e97f107a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/user_prog.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+#ifndef PERF_MAX_STACK_DEPTH
+#define PERF_MAX_STACK_DEPTH         127
+#endif
+
+typedef __u64 stack_trace_t[PERF_MAX_STACK_DEPTH];
+
+struct {
+	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
+	__uint(max_entries, 16384);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(stack_trace_t));
+} stackmap SEC(".maps");
+
+volatile int cpu_match = 1;
+volatile __u64 sum = 1;
+volatile int get_stack_success = 0;
+volatile int get_stackid_success = 0;
+volatile __u64 stacktrace[PERF_MAX_STACK_DEPTH];
+
+SEC("user")
+int user_func(struct bpf_user_prog_ctx *ctx)
+{
+	int cpu = bpf_get_smp_processor_id();
+	__u32 key = cpu;
+	long stackid, err;
+
+	/* check the program runs on the right cpu */
+	if (ctx->args[0] && ctx->args[0] != cpu + 1)
+		cpu_match = 0;
+
+	/* check the sum of arguments are correct */
+	sum = ctx->args[0] + ctx->args[1] + ctx->args[2] +
+		ctx->args[3] + ctx->args[4];
+
+	/* check bpf_get_stackid works */
+	stackid = bpf_get_stackid(ctx, &stackmap, 0);
+	if (stackid >= 0)
+		get_stackid_success++;
+
+	/* check bpf_get_stack works */
+	err = bpf_get_stack(ctx, (void *)stacktrace,
+			    PERF_MAX_STACK_DEPTH * sizeof(__u64),
+			    BPF_F_USER_STACK);
+	if (err >= 0)
+		get_stack_success++;
+
+	return cpu + 2;
+}
-- 
2.24.1