selftests/bpf: Use target-less SEC() definitions in various tests

Add new or modify existing SEC() definitions to be target-less and
validate that libbpf handles such program definitions correctly.

For kprobe/kretprobe we also add explicit test that generic
bpf_program__attach() works in cases when kprobe definition contains
proper target. It wasn't previously tested as selftests code always
explicitly specified the target regardless.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220428185349.3799599-4-andrii@kernel.org

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

@@ -55,6 +55,7 @@ void test_attach_probe(void)
 	if (!ASSERT_OK_PTR(skel->bss, "check_bss"))
 		goto cleanup;
 
+	/* manual-attach kprobe/kretprobe */
 	kprobe_link = bpf_program__attach_kprobe(skel->progs.handle_kprobe,
 						 false /* retprobe */,
 						 SYS_NANOSLEEP_KPROBE_NAME);
@@ -69,6 +70,13 @@ void test_attach_probe(void)
 		goto cleanup;
 	skel->links.handle_kretprobe = kretprobe_link;
 
+	/* auto-attachable kprobe and kretprobe */
+	skel->links.handle_kprobe_auto = bpf_program__attach(skel->progs.handle_kprobe_auto);
+	ASSERT_OK_PTR(skel->links.handle_kprobe_auto, "attach_kprobe_auto");
+
+	skel->links.handle_kretprobe_auto = bpf_program__attach(skel->progs.handle_kretprobe_auto);
+	ASSERT_OK_PTR(skel->links.handle_kretprobe_auto, "attach_kretprobe_auto");
+
 	if (!legacy)
 		ASSERT_EQ(uprobe_ref_ctr, 0, "uprobe_ref_ctr_before");
 
@@ -157,7 +165,9 @@ void test_attach_probe(void)
 	trigger_func2();
 
 	ASSERT_EQ(skel->bss->kprobe_res, 1, "check_kprobe_res");
+	ASSERT_EQ(skel->bss->kprobe2_res, 11, "check_kprobe_auto_res");
 	ASSERT_EQ(skel->bss->kretprobe_res, 2, "check_kretprobe_res");
+	ASSERT_EQ(skel->bss->kretprobe2_res, 22, "check_kretprobe_auto_res");
 	ASSERT_EQ(skel->bss->uprobe_res, 3, "check_uprobe_res");
 	ASSERT_EQ(skel->bss->uretprobe_res, 4, "check_uretprobe_res");
 	ASSERT_EQ(skel->bss->uprobe_byname_res, 5, "check_uprobe_byname_res");

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

@@ -140,14 +140,14 @@ test_attach_api(const char *pattern, struct bpf_kprobe_multi_opts *opts)
 		goto cleanup;
 
 	skel->bss->pid = getpid();
-	link1 = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe,
+	link1 = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						      pattern, opts);
 	if (!ASSERT_OK_PTR(link1, "bpf_program__attach_kprobe_multi_opts"))
 		goto cleanup;
 
 	if (opts) {
 		opts->retprobe = true;
-		link2 = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kretprobe,
+		link2 = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kretprobe_manual,
 							      pattern, opts);
 		if (!ASSERT_OK_PTR(link2, "bpf_program__attach_kprobe_multi_opts"))
 			goto cleanup;
@@ -232,7 +232,7 @@ static void test_attach_api_fails(void)
 	skel->bss->pid = getpid();
 
 	/* fail_1 - pattern and opts NULL */
-	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe,
+	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     NULL, NULL);
 	if (!ASSERT_ERR_PTR(link, "fail_1"))
 		goto cleanup;
@@ -246,7 +246,7 @@ static void test_attach_api_fails(void)
 	opts.cnt = ARRAY_SIZE(syms);
 	opts.cookies = NULL;
 
-	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe,
+	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     NULL, &opts);
 	if (!ASSERT_ERR_PTR(link, "fail_2"))
 		goto cleanup;
@@ -260,7 +260,7 @@ static void test_attach_api_fails(void)
 	opts.cnt = ARRAY_SIZE(syms);
 	opts.cookies = NULL;
 
-	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe,
+	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     "ksys_*", &opts);
 	if (!ASSERT_ERR_PTR(link, "fail_3"))
 		goto cleanup;
@@ -274,7 +274,7 @@ static void test_attach_api_fails(void)
 	opts.cnt = ARRAY_SIZE(syms);
 	opts.cookies = NULL;
 
-	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe,
+	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     "ksys_*", &opts);
 	if (!ASSERT_ERR_PTR(link, "fail_4"))
 		goto cleanup;
@@ -288,7 +288,7 @@ static void test_attach_api_fails(void)
 	opts.cnt = 0;
 	opts.cookies = cookies;
 
-	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe,
+	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     "ksys_*", &opts);
 	if (!ASSERT_ERR_PTR(link, "fail_5"))
 		goto cleanup;

tools/testing/selftests/bpf/progs/kprobe_multi.c

@@ -98,3 +98,17 @@ int test_kretprobe(struct pt_regs *ctx)
 	kprobe_multi_check(ctx, true);
 	return 0;
 }
+
+SEC("kprobe.multi")
+int test_kprobe_manual(struct pt_regs *ctx)
+{
+	kprobe_multi_check(ctx, false);
+	return 0;
+}
+
+SEC("kretprobe.multi")
+int test_kretprobe_manual(struct pt_regs *ctx)
+{
+	kprobe_multi_check(ctx, true);
+	return 0;
+}

tools/testing/selftests/bpf/progs/test_attach_probe.c

@@ -5,9 +5,12 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
 
 int kprobe_res = 0;
+int kprobe2_res = 0;
 int kretprobe_res = 0;
+int kretprobe2_res = 0;
 int uprobe_res = 0;
 int uretprobe_res = 0;
 int uprobe_byname_res = 0;
@@ -15,20 +18,34 @@ int uretprobe_byname_res = 0;
 int uprobe_byname2_res = 0;
 int uretprobe_byname2_res = 0;
 
-SEC("kprobe/sys_nanosleep")
+SEC("kprobe")
 int handle_kprobe(struct pt_regs *ctx)
 {
 	kprobe_res = 1;
 	return 0;
 }
 
-SEC("kretprobe/sys_nanosleep")
-int BPF_KRETPROBE(handle_kretprobe)
+SEC("kprobe/" SYS_PREFIX "sys_nanosleep")
+int BPF_KPROBE(handle_kprobe_auto)
+{
+	kprobe2_res = 11;
+	return 0;
+}
+
+SEC("kretprobe")
+int handle_kretprobe(struct pt_regs *ctx)
 {
 	kretprobe_res = 2;
 	return 0;
 }
 
+SEC("kretprobe/" SYS_PREFIX "sys_nanosleep")
+int BPF_KRETPROBE(handle_kretprobe_auto)
+{
+	kretprobe2_res = 22;
+	return 0;
+}
+
 SEC("uprobe")
 int handle_uprobe(struct pt_regs *ctx)
 {

tools/testing/selftests/bpf/progs/test_module_attach.c

@@ -64,7 +64,7 @@ int BPF_PROG(handle_fentry,
 
 __u32 fentry_manual_read_sz = 0;
 
-SEC("fentry/placeholder")
+SEC("fentry")
 int BPF_PROG(handle_fentry_manual,
 	     struct file *file, struct kobject *kobj,
 	     struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len)