selftests/bpf: add C-level selftests for indirect jumps

Add C-level selftests for indirect jumps to validate LLVM and libbpf
functionality. The tests are intentionally disabled, to be run
locally by developers, but will not make the CI red.

Signed-off-by: Anton Protopopov <[email protected]>

Author: aspsk

tools/testing/selftests/bpf/Makefile

@@ -454,7 +454,9 @@ BPF_CFLAGS = -g -Wall -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN)	\
 	     -I$(abspath $(OUTPUT)/../usr/include)			\
 	     -std=gnu11		 					\
 	     -fno-strict-aliasing 					\
-	     -Wno-compare-distinct-pointer-types
+	     -Wno-compare-distinct-pointer-types			\
+	     -Wno-initializer-overrides					\
+	     #
 # TODO: enable me -Wsign-compare
 
 CLANG_CFLAGS = $(CLANG_SYS_INCLUDES)

tools/testing/selftests/bpf/prog_tests/bpf_gotox.c

@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+
+#include <linux/if_ether.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/in6.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
+
+#include <sys/syscall.h>
+#include <bpf/bpf.h>
+
+#include "bpf_gotox.skel.h"
+
+/* Disable tests for now, as CI runs with LLVM-20 */
+#if 0
+static void __test_run(struct bpf_program *prog, void *ctx_in, size_t ctx_size_in)
+{
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+			    .ctx_in = ctx_in,
+			    .ctx_size_in = ctx_size_in,
+		   );
+	int err, prog_fd;
+
+	prog_fd = bpf_program__fd(prog);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run_opts err");
+}
+
+static void check_simple(struct bpf_gotox *skel,
+			 struct bpf_program *prog,
+			 __u64 ctx_in,
+			 __u64 expected)
+{
+	skel->bss->ret_user = 0;
+
+	__test_run(prog, &ctx_in, sizeof(ctx_in));
+
+	if (!ASSERT_EQ(skel->bss->ret_user, expected, "skel->bss->ret_user"))
+		return;
+}
+
+static void check_simple_fentry(struct bpf_gotox *skel,
+				struct bpf_program *prog,
+				__u64 ctx_in,
+				__u64 expected)
+{
+	skel->bss->in_user = ctx_in;
+	skel->bss->ret_user = 0;
+
+	/* trigger */
+	usleep(1);
+
+	if (!ASSERT_EQ(skel->bss->ret_user, expected, "skel->bss->ret_user"))
+		return;
+}
+
+/* validate that for two loads of the same jump table libbpf generates only one map */
+static void check_one_map_two_jumps(struct bpf_gotox *skel)
+{
+	struct bpf_prog_info prog_info;
+	struct bpf_map_info map_info;
+	__u32 len;
+	__u32 map_ids[16];
+	int prog_fd, map_fd;
+	int ret;
+	int i;
+	bool seen = false;
+
+	memset(&prog_info, 0, sizeof(prog_info));
+	prog_info.map_ids = (long)map_ids;
+	prog_info.nr_map_ids = ARRAY_SIZE(map_ids);
+	prog_fd = bpf_program__fd(skel->progs.one_map_two_jumps);
+	if (!ASSERT_GE(prog_fd, 0, "bpf_program__fd(one_map_two_jumps)"))
+		return;
+
+	len = sizeof(prog_info);
+	ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &len);
+	if (!ASSERT_OK(ret, "bpf_obj_get_info_by_fd(prog_fd)"))
+		return;
+
+	for (i = 0; i < prog_info.nr_map_ids; i++) {
+		map_fd  = bpf_map_get_fd_by_id(map_ids[i]);
+		if (!ASSERT_GE(map_fd, 0, "bpf_program__fd(one_map_two_jumps)"))
+			return;
+
+		len = sizeof(map_info);
+		memset(&map_info, 0, len);
+		ret = bpf_obj_get_info_by_fd(map_fd, &map_info, &len);
+		if (!ASSERT_OK(ret, "bpf_obj_get_info_by_fd(map_fd)")) {
+			close(map_fd);
+			return;
+		}
+
+		if (map_info.type == BPF_MAP_TYPE_INSN_ARRAY) {
+			if (!ASSERT_EQ(seen, false, "more than one INSN_ARRAY map")) {
+				close(map_fd);
+				return;
+			}
+			seen = true;
+		}
+		close(map_fd);
+	}
+
+	ASSERT_EQ(seen, true, "no INSN_ARRAY map");
+}
+
+static void check_gotox_skel(struct bpf_gotox *skel)
+{
+	int i;
+	__u64 in[]   = {0, 1, 2, 3, 4,  5, 77};
+	__u64 out[]  = {2, 3, 4, 5, 7, 19, 19};
+	__u64 out2[] = {103, 104, 107, 205, 115, 1019, 1019};
+	__u64 in3[]  = {0, 11, 27, 31, 22, 45, 99};
+	__u64 out3[] = {2,  3,  4,  5, 19, 19, 19};
+	__u64 in4[]  = {0, 1, 2, 3, 4,  5, 77};
+	__u64 out4[] = {12, 15, 7 , 15, 12, 15, 15};
+
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.simple_test, in[i], out[i]);
+
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.simple_test2, in[i], out[i]);
+
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.two_switches, in[i], out2[i]);
+
+	if (0) for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.big_jump_table, in3[i], out3[i]);
+
+	if (0) for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.one_jump_two_maps, in4[i], out4[i]);
+
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.use_static_global1, in[i], out[i]);
+
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.use_static_global2, in[i], out[i]);
+
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.use_nonstatic_global1, in[i], out[i]);
+
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple(skel, skel->progs.use_nonstatic_global2, in[i], out[i]);
+
+	bpf_program__attach(skel->progs.simple_test_other_sec);
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple_fentry(skel, skel->progs.simple_test_other_sec, in[i], out[i]);
+
+	bpf_program__attach(skel->progs.use_static_global_other_sec);
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple_fentry(skel, skel->progs.use_static_global_other_sec, in[i], out[i]);
+
+	bpf_program__attach(skel->progs.use_nonstatic_global_other_sec);
+	for (i = 0; i < ARRAY_SIZE(in); i++)
+		check_simple_fentry(skel, skel->progs.use_nonstatic_global_other_sec, in[i], out[i]);
+
+	if (0) check_one_map_two_jumps(skel);
+}
+
+void test_bpf_gotox(void)
+{
+	struct bpf_gotox *skel;
+	int ret;
+
+	skel = bpf_gotox__open();
+	if (!ASSERT_NEQ(skel, NULL, "bpf_gotox__open"))
+		return;
+
+	ret = bpf_gotox__load(skel);
+	if (!ASSERT_OK(ret, "bpf_gotox__load"))
+		return;
+
+	check_gotox_skel(skel);
+
+	bpf_gotox__destroy(skel);
+}
+#else
+void test_bpf_gotox(void)
+{
+}
+#endif