Add a selftest validating various aspects of libbpf's handling of custom
SEC() handlers. It also demonstrates how libraries can ensure very early
callbacks registration and unregistration using
__attribute__((constructor))/__attribute__((destructor)) functions.
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
.../bpf/prog_tests/custom_sec_handlers.c | 136 ++++++++++++++++++
.../bpf/progs/test_custom_sec_handlers.c | 51 +++++++
2 files changed, 187 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c
create mode 100644 tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c
diff --git a/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c b/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c
new file mode 100644
index 000000000000..8e43c5f21878
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/custom_sec_handlers.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Facebook */
+
+#include <test_progs.h>
+#include "test_custom_sec_handlers.skel.h"
+
+#define COOKIE_ABC1 1
+#define COOKIE_ABC2 2
+#define COOKIE_CUSTOM 3
+#define COOKIE_FALLBACK 4
+
+static int custom_init_prog(struct bpf_program *prog, long cookie)
+{
+ if (cookie == COOKIE_ABC1)
+ bpf_program__set_autoload(prog, false);
+
+ return 0;
+}
+
+static int custom_preload_prog(struct bpf_program *prog,
+ struct bpf_prog_load_opts *opts, long cookie)
+{
+ return 0;
+}
+
+static int custom_attach_prog(const struct bpf_program *prog, long cookie,
+ struct bpf_link **link)
+{
+ switch (cookie) {
+ case COOKIE_ABC2:
+ *link = bpf_program__attach_raw_tracepoint(prog, "sys_enter");
+ return libbpf_get_error(*link);
+ case COOKIE_CUSTOM:
+ *link = bpf_program__attach_tracepoint(prog, "syscalls", "sys_enter_nanosleep");
+ return libbpf_get_error(*link);
+ case COOKIE_FALLBACK:
+ /* no auto-attach for SEC("xyz") */
+ *link = NULL;
+ return 0;
+ default:
+ ASSERT_FALSE(true, "unexpected cookie");
+ return -EINVAL;
+ }
+}
+
+static int abc1_id;
+static int abc2_id;
+static int custom_id;
+static int fallback_id;
+
+__attribute__((constructor))
+static void register_sec_handlers(void)
+{
+ abc1_id = libbpf_register_prog_handler("abc",
+ BPF_PROG_TYPE_RAW_TRACEPOINT, 0,
+ custom_init_prog, custom_preload_prog,
+ custom_attach_prog,
+ COOKIE_ABC1, NULL);
+ abc2_id = libbpf_register_prog_handler("abc/",
+ BPF_PROG_TYPE_RAW_TRACEPOINT, 0,
+ custom_init_prog, custom_preload_prog,
+ custom_attach_prog,
+ COOKIE_ABC2, NULL);
+ custom_id = libbpf_register_prog_handler("custom+",
+ BPF_PROG_TYPE_TRACEPOINT, 0,
+ custom_init_prog, custom_preload_prog,
+ custom_attach_prog,
+ COOKIE_CUSTOM, NULL);
+}
+
+__attribute__((destructor))
+static void unregister_sec_handlers(void)
+{
+ libbpf_unregister_prog_handler(abc1_id);
+ libbpf_unregister_prog_handler(abc2_id);
+ libbpf_unregister_prog_handler(custom_id);
+}
+
+void test_custom_sec_handlers(void)
+{
+ struct test_custom_sec_handlers* skel;
+ int err;
+
+ ASSERT_GT(abc1_id, 0, "abc1_id");
+ ASSERT_GT(abc2_id, 0, "abc2_id");
+ ASSERT_GT(custom_id, 0, "custom_id");
+
+ fallback_id = libbpf_register_prog_handler(NULL, /* fallback handler */
+ BPF_PROG_TYPE_KPROBE, 0,
+ custom_init_prog, custom_preload_prog,
+ custom_attach_prog,
+ COOKIE_FALLBACK, NULL);
+ if (!ASSERT_GT(fallback_id, 0, "fallback_id"))
+ return;
+
+ /* open skeleton and validate assumptions */
+ skel = test_custom_sec_handlers__open();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ goto cleanup;
+
+ ASSERT_EQ(bpf_program__type(skel->progs.abc1), BPF_PROG_TYPE_RAW_TRACEPOINT, "abc1_type");
+ ASSERT_FALSE(bpf_program__autoload(skel->progs.abc1), "abc1_autoload");
+
+ ASSERT_EQ(bpf_program__type(skel->progs.abc2), BPF_PROG_TYPE_RAW_TRACEPOINT, "abc2_type");
+ ASSERT_EQ(bpf_program__type(skel->progs.custom1), BPF_PROG_TYPE_TRACEPOINT, "custom1_type");
+ ASSERT_EQ(bpf_program__type(skel->progs.custom2), BPF_PROG_TYPE_TRACEPOINT, "custom2_type");
+ ASSERT_EQ(bpf_program__type(skel->progs.xyz), BPF_PROG_TYPE_KPROBE, "xyz_type");
+
+ skel->rodata->my_pid = getpid();
+
+ /* now attempt to load everything */
+ err = test_custom_sec_handlers__load(skel);
+ if (!ASSERT_OK(err, "skel_load"))
+ goto cleanup;
+
+ /* now try to auto-attach everything */
+ err = test_custom_sec_handlers__attach(skel);
+ if (!ASSERT_OK(err, "skel_attach"))
+ goto cleanup;
+
+ /* trigger programs */
+ usleep(1);
+
+ /* SEC("abc") is set to not auto-loaded */
+ ASSERT_FALSE(skel->bss->abc1_called, "abc1_called");
+ ASSERT_TRUE(skel->bss->abc2_called, "abc2_called");
+ ASSERT_TRUE(skel->bss->custom1_called, "custom1_called");
+ ASSERT_TRUE(skel->bss->custom2_called, "custom2_called");
+ /* SEC("xyz") shouldn't be auto-attached */
+ ASSERT_FALSE(skel->bss->xyz_called, "xyz_called");
+
+cleanup:
+ test_custom_sec_handlers__destroy(skel);
+
+ ASSERT_OK(libbpf_unregister_prog_handler(fallback_id), "unregister_fallback");
+}
diff --git a/tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c b/tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c
new file mode 100644
index 000000000000..2df368783678
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_custom_sec_handlers.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+const volatile int my_pid;
+
+bool abc1_called;
+bool abc2_called;
+bool custom1_called;
+bool custom2_called;
+bool xyz_called;
+
+SEC("abc")
+int abc1(void *ctx)
+{
+ abc1_called = true;
+ return 0;
+}
+
+SEC("abc/whatever")
+int abc2(void *ctx)
+{
+ abc2_called = true;
+ return 0;
+}
+
+SEC("custom")
+int custom1(void *ctx)
+{
+ custom1_called = true;
+ return 0;
+}
+
+SEC("custom/something")
+int custom2(void *ctx)
+{
+ custom2_called = true;
+ return 0;
+}
+
+SEC("xyz/blah")
+int xyz(void *ctx)
+{
+ xyz_called = true;
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.30.2
