[bpf-next,6/6] selftests/bpf: add tests for libbpf-provided externs

diff --git a/tools/testing/selftests/bpf/prog_tests/core_extern.c b/tools/testing/selftests/bpf/prog_tests/core_extern.c
new file mode 100644
index 000000000000..2a87a5f1de4d
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/core_extern.c
@@ -0,0 +1,186 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <sys/mman.h>
+#include <sys/utsname.h>
+#include <linux/version.h>
+
+static size_t roundup_page(size_t sz)
+{
+	long page_size = sysconf(_SC_PAGE_SIZE);
+	return (sz + page_size - 1) / page_size * page_size;
+}
+
+static uint32_t get_kernel_version(void)
+{
+	uint32_t major, minor, patch;
+	struct utsname info;
+
+	uname(&info);
+	if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
+		return 0;
+	return KERNEL_VERSION(major, minor, patch);
+}
+
+struct data {
+	uint64_t kern_ver;
+	uint64_t tristate_val;
+	uint64_t bool_val;
+	uint64_t int_val;
+	uint64_t missing_val;
+};
+
+static struct test_case {
+	const char *name;
+	const char *cfg;
+	const char *cfg_path;
+	bool fails;
+	struct data data;
+} test_cases[] = {
+	{ .name = "default search path", .cfg_path = NULL },
+	{ .name = "/proc/config.gz", .cfg_path = "/proc/config.gz" },
+	{ .name = "missing config", .fails = true,
+	  .cfg_path = "/proc/invalid-config.gz" },
+	{
+		.name = "custom values",
+		.cfg = "CONFIG_TRISTATE=m\n"
+		       "CONFIG_BOOL=y\n"
+		       "CONFIG_INT=123456\n",
+		.data = {
+			.tristate_val = 2,
+			.bool_val = 1,
+			.int_val = 123456,
+		},
+	},
+	{
+		/* there is no real typing, so any valid value is accepted */
+		.name = "mixed up types",
+		.cfg = "CONFIG_TRISTATE=123\n"
+		       "CONFIG_BOOL=m\n"
+		       "CONFIG_INT=y\n",
+		.data = {
+			.tristate_val = 123,
+			.bool_val = 2,
+			.int_val = 1,
+		},
+	},
+	{
+		/* somewhat weird behavior of strtoull */
+		.name = "negative int",
+		.cfg = "CONFIG_INT=-12\n",
+		.data = { .int_val = (uint64_t)-12 },
+	},
+	{ .name = "bad tristate", .fails = true, .cfg = "CONFIG_TRISTATE=M" },
+	{ .name = "bad bool", .fails = true, .cfg = "CONFIG_BOOL=X" },
+	{ .name = "int (not int)", .fails = true, .cfg = "CONFIG_INT=abc" },
+	{ .name = "int (string)", .fails = true, .cfg = "CONFIG_INT=\"abc\"" },
+	{ .name = "int (empty)", .fails = true, .cfg = "CONFIG_INT=" },
+	{ .name = "int (mixed up 1)", .fails = true, .cfg = "CONFIG_INT=123abc",
+	  .fails = true, },
+	{ .name = "int (mixed up 2)", .fails = true, .cfg = "CONFIG_INT=123abc\n",
+	  .fails = true, },
+	{ .name = "int (too big)", .fails = true,
+	  .cfg = "CONFIG_INT=123456789123456789123\n" },
+};
+
+void test_core_extern(void)
+{
+	const char *file = "test_core_extern.o";
+	const char *probe_name = "raw_tp/sys_enter";
+	const char *tp_name = "sys_enter";
+	const size_t bss_sz = roundup_page(sizeof(struct data));
+	const uint32_t kern_ver = get_kernel_version();
+	int err, duration = 0, i;
+	struct bpf_program *prog;
+	struct bpf_object *obj;
+	struct bpf_link *link = NULL;
+	struct bpf_map *bss_map;
+	void *bss_mmaped = NULL;
+	volatile struct data *data;
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+		char tmp_cfg_path[] = "/tmp/test_core_extern_cfg.XXXXXX";
+		const struct test_case *t = &test_cases[i];
+		DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+			.kernel_config_path = t->cfg_path,
+		);
+
+		if (!test__start_subtest(t->name))
+			continue;
+
+		if (t->cfg) {
+			size_t n = strlen(t->cfg) + 1;
+			int fd = mkstemp(tmp_cfg_path);
+
+			if (CHECK(fd < 0, "mkstemp", "errno: %d\n", errno))
+				continue;
+			printf("using '%s' as config file\n", tmp_cfg_path);
+			if (CHECK_FAIL(write(fd, t->cfg, n) != n))
+				continue;
+			close(fd);
+			opts.kernel_config_path = tmp_cfg_path;
+		}
+
+		obj = bpf_object__open_file("test_core_extern.o", &opts);
+		if (t->fails) {
+			CHECK(!IS_ERR(obj), "obj_open",
+			      "shouldn't succeed opening '%s'!\n", file);
+			goto cleanup;
+		} else {
+			if (CHECK(IS_ERR(obj), "obj_open",
+				  "failed to open '%s': %ld\n",
+				  file, PTR_ERR(obj)))
+				goto cleanup;
+		}
+		prog = bpf_object__find_program_by_title(obj, probe_name);
+		if (CHECK(!prog, "find_prog", "prog %s missing\n", probe_name))
+			goto cleanup;
+		err = bpf_object__load(obj);
+		if (CHECK(err, "obj_load", "failed to load prog '%s': %d\n",
+			  probe_name, err))
+			goto cleanup;
+		bss_map = bpf_object__find_map_by_name(obj, "test_cor.bss");
+		if (CHECK(!bss_map, "find_bss_map", ".bss map not found\n"))
+			goto cleanup;
+		bss_mmaped = mmap(NULL, bss_sz, PROT_READ | PROT_WRITE,
+				  MAP_SHARED, bpf_map__fd(bss_map), 0);
+		if (CHECK(bss_mmaped == MAP_FAILED, "bss_mmap",
+			  ".bss mmap failed: %d\n", errno)) {
+			bss_mmaped = NULL;
+			goto cleanup;
+		}
+		data = bss_mmaped;
+
+		link = bpf_program__attach_raw_tracepoint(prog, tp_name);
+		if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n", PTR_ERR(link)))
+			goto cleanup;
+
+		usleep(1);
+
+		CHECK(data->kern_ver != kern_ver, "kern_ver",
+		      "exp %x, got %lx\n", kern_ver, data->kern_ver);
+		CHECK(data->missing_val != 0xDEADC0DE, "missing_val",
+		      "exp %x, got %lx\n", 0xDEADC0DE, data->missing_val);
+		CHECK(data->bool_val != t->data.bool_val, "bool_val",
+		      "exp %lx, got %lx\n", t->data.bool_val, data->bool_val);
+		CHECK(data->tristate_val != t->data.tristate_val,
+		      "tristate_val", "exp %lx, got %lx\n",
+		      t->data.tristate_val, data->tristate_val);
+		CHECK(data->int_val != t->data.int_val, "int_val",
+		      "exp %lx, got %lx\n", t->data.int_val, data->int_val);
+
+cleanup:
+		if (t->cfg)
+			unlink(tmp_cfg_path);
+		if (bss_mmaped) {
+			CHECK_FAIL(munmap(bss_mmaped, bss_sz));
+			bss_mmaped = NULL;
+			data = NULL;
+		}
+		if (!IS_ERR_OR_NULL(link)) {
+			bpf_link__destroy(link);
+			link = NULL;
+		}
+		if (!IS_ERR_OR_NULL(obj))
+			bpf_object__close(obj);
+	}
+}
diff --git a/tools/testing/selftests/bpf/progs/test_core_extern.c b/tools/testing/selftests/bpf/progs/test_core_extern.c
new file mode 100644
index 000000000000..adbc74113265
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_core_extern.c
@@ -0,0 +1,43 @@ 
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017 Facebook
+
+#include <stdint.h>
+#include <linux/ptrace.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+/* non-existing BPF helper, to test dead code elimination */
+static int (*bpf_missing_helper)(const void *arg1, int arg2) = (void *) 999;
+
+extern uint64_t LINUX_KERNEL_VERSION;
+extern uint64_t CONFIG_TRISTATE;
+extern uint64_t CONFIG_BOOL;
+extern uint64_t CONFIG_INT;
+extern uint64_t CONFIG_MISSING;
+
+volatile struct {
+	uint64_t kern_ver;
+	uint64_t tristate_val;
+	uint64_t bool_val;
+	uint64_t int_val;
+	uint64_t missing_val;
+} out = {};
+
+SEC("raw_tp/sys_enter")
+int handle_sys_enter(struct pt_regs *ctx)
+{
+	out.kern_ver = LINUX_KERNEL_VERSION;
+	out.tristate_val = CONFIG_TRISTATE;
+	out.bool_val = CONFIG_BOOL;
+	out.int_val = CONFIG_INT;
+
+	if (CONFIG_MISSING)
+		/* invalid, but dead code - never executed */
+		out.missing_val = bpf_missing_helper(ctx, 123);
+	else
+		out.missing_val = 0xDEADC0DE;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";