[PATCH v2 bpf-next 0/3] Add target-less tracing SEC() definitions

[PATCH v2 bpf-next 0/3] Add target-less tracing SEC() definitions

[Andrii Nakryiko]

Allow specifying "target-less" SEC() definitions for tracing BPF programs,
both non-BTF-backed (kprobes, tracepoints, raw tracepoints) and BTF-backed
(fentry/fexit, iter, lsm, etc).

There are various situations where attach target cannot be known at
compilation time, so libbpf's insistence on specifying something leads to
users having to add random test like SEC("kprobe/whatever") and then
specifying correct target at runtime using APIs like
bpf_program__attach_kprobe().

So this patch set improves ergonomics by allowing simple SEC() definitions
that define BPF program type and nothing else. Such programs won't be
auto-attachable, of course, but they also won't fail skeleton auto-attachment,
just like we do this for uprobes.

v1->v2:
  - rebased and added Song's acks.

Cc: Delyan Kratunov <delyank@fb.com>
Cc: Jiri Olsa <jolsa@kernel.org>

Andrii Nakryiko (3):
  libbpf: allow "incomplete" basic tracing SEC() definitions
  libbpf: support target-less SEC() definitions for BTF-backed programs
  selftests/bpf: use target-less SEC() definitions in various tests

 tools/lib/bpf/libbpf.c                        | 118 ++++++++++++------
 .../selftests/bpf/prog_tests/attach_probe.c   |  10 ++
 .../bpf/prog_tests/kprobe_multi_test.c        |  14 +--
 .../selftests/bpf/progs/kprobe_multi.c        |  14 +++
 .../selftests/bpf/progs/test_attach_probe.c   |  23 +++-
 .../selftests/bpf/progs/test_module_attach.c  |   2 +-
 6 files changed, 135 insertions(+), 46 deletions(-)

-- 
2.30.2

[PATCH v2 bpf-next 1/3] libbpf: allow "incomplete" basic tracing SEC() definitions

[Andrii Nakryiko]

In a lot of cases the target of kprobe/kretprobe, tracepoint, raw
tracepoint, etc BPF program might not be known at the compilation time
and will be discovered at runtime. This was always a supported case by
libbpf, with APIs like bpf_program__attach_{kprobe,tracepoint,etc}()
accepting full target definition, regardless of what was defined in
SEC() definition in BPF source code.

Unfortunately, up till now libbpf still enforced users to specify at
least something for the fake target, e.g., SEC("kprobe/whatever"), which
is cumbersome and somewhat misleading.

This patch allows target-less SEC() definitions for basic tracing BPF
program types:
  - kprobe/kretprobe;
  - multi-kprobe/multi-kretprobe;
  - tracepoints;
  - raw tracepoints.

Such target-less SEC() definitions are meant to specify declaratively
proper BPF program type only. Attachment of them will have to be handled
programmatically using correct APIs. As such, skeleton's auto-attachment
of such BPF programs is skipped and generic bpf_program__attach() will
fail, if attempted, due to the lack of enough target information.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 69 +++++++++++++++++++++++++++++++-----------
 1 file changed, 51 insertions(+), 18 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 73a5192defb3..e840e48d3a76 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8853,22 +8853,22 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("socket",		SOCKET_FILTER, 0, SEC_NONE | SEC_SLOPPY_PFX),
 	SEC_DEF("sk_reuseport/migrate",	SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE | SEC_SLOPPY_PFX),
 	SEC_DEF("sk_reuseport",		SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE | SEC_SLOPPY_PFX),
-	SEC_DEF("kprobe/",		KPROBE,	0, SEC_NONE, attach_kprobe),
+	SEC_DEF("kprobe+",		KPROBE,	0, SEC_NONE, attach_kprobe),
 	SEC_DEF("uprobe+",		KPROBE,	0, SEC_NONE, attach_uprobe),
-	SEC_DEF("kretprobe/",		KPROBE, 0, SEC_NONE, attach_kprobe),
+	SEC_DEF("kretprobe+",		KPROBE, 0, SEC_NONE, attach_kprobe),
 	SEC_DEF("uretprobe+",		KPROBE, 0, SEC_NONE, attach_uprobe),
-	SEC_DEF("kprobe.multi/",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
-	SEC_DEF("kretprobe.multi/",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+	SEC_DEF("kprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+	SEC_DEF("kretprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
 	SEC_DEF("usdt+",		KPROBE,	0, SEC_NONE, attach_usdt),
 	SEC_DEF("tc",			SCHED_CLS, 0, SEC_NONE),
 	SEC_DEF("classifier",		SCHED_CLS, 0, SEC_NONE | SEC_SLOPPY_PFX | SEC_DEPRECATED),
 	SEC_DEF("action",		SCHED_ACT, 0, SEC_NONE | SEC_SLOPPY_PFX),
-	SEC_DEF("tracepoint/",		TRACEPOINT, 0, SEC_NONE, attach_tp),
-	SEC_DEF("tp/",			TRACEPOINT, 0, SEC_NONE, attach_tp),
-	SEC_DEF("raw_tracepoint/",	RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
-	SEC_DEF("raw_tp/",		RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
-	SEC_DEF("raw_tracepoint.w/",	RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
-	SEC_DEF("raw_tp.w/",		RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("tracepoint+",		TRACEPOINT, 0, SEC_NONE, attach_tp),
+	SEC_DEF("tp+",			TRACEPOINT, 0, SEC_NONE, attach_tp),
+	SEC_DEF("raw_tracepoint+",	RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tp+",		RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tracepoint.w+",	RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tp.w+",		RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
 	SEC_DEF("tp_btf/",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
 	SEC_DEF("fentry/",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
 	SEC_DEF("fmod_ret/",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
@@ -10595,6 +10595,12 @@ static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf
 	char *func;
 	int n;
 
+	*link = NULL;
+
+	/* no auto-attach for SEC("kprobe") and SEC("kretprobe") */
+	if (strcmp(prog->sec_name, "kprobe") == 0 || strcmp(prog->sec_name, "kretprobe") == 0)
+		return 0;
+
 	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/");
 	if (opts.retprobe)
 		func_name = prog->sec_name + sizeof("kretprobe/") - 1;
@@ -10625,6 +10631,13 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru
 	char *pattern;
 	int n;
 
+	*link = NULL;
+
+	/* no auto-attach for SEC("kprobe.multi") and SEC("kretprobe.multi") */
+	if (strcmp(prog->sec_name, "kprobe.multi") == 0 ||
+	    strcmp(prog->sec_name, "kretprobe.multi") == 0)
+		return 0;
+
 	opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe.multi/");
 	if (opts.retprobe)
 		spec = prog->sec_name + sizeof("kretprobe.multi/") - 1;
@@ -11329,6 +11342,12 @@ static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_lin
 	if (!sec_name)
 		return -ENOMEM;
 
+	*link = NULL;
+
+	/* no auto-attach for SEC("tp") or SEC("tracepoint") */
+	if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0)
+		return 0;
+
 	/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
 	if (str_has_pfx(prog->sec_name, "tp/"))
 		tp_cat = sec_name + sizeof("tp/") - 1;
@@ -11380,20 +11399,34 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *pr
 static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
 {
 	static const char *const prefixes[] = {
-		"raw_tp/",
-		"raw_tracepoint/",
-		"raw_tp.w/",
-		"raw_tracepoint.w/",
+		"raw_tp",
+		"raw_tracepoint",
+		"raw_tp.w",
+		"raw_tracepoint.w",
 	};
 	size_t i;
 	const char *tp_name = NULL;
 
+	*link = NULL;
+
 	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
-		if (str_has_pfx(prog->sec_name, prefixes[i])) {
-			tp_name = prog->sec_name + strlen(prefixes[i]);
-			break;
-		}
+		size_t pfx_len;
+
+		if (!str_has_pfx(prog->sec_name, prefixes[i]))
+			continue;
+
+		pfx_len = strlen(prefixes[i]);
+		/* no auto-attach case of, e.g., SEC("raw_tp") */
+		if (prog->sec_name[pfx_len] == '\0')
+			return 0;
+
+		if (prog->sec_name[pfx_len] != '/')
+			continue;
+
+		tp_name = prog->sec_name + pfx_len + 1;
+		break;
 	}
+
 	if (!tp_name) {
 		pr_warn("prog '%s': invalid section name '%s'\n",
 			prog->name, prog->sec_name);
-- 
2.30.2

[PATCH v2 bpf-next 2/3] libbpf: support target-less SEC() definitions for BTF-backed programs

[Andrii Nakryiko]

Similar to previous patch, support target-less definitions like
SEC("fentry"), SEC("freplace"), etc. For such BTF-backed program types
it is expected that user will specify BTF target programmatically at
runtime using bpf_program__set_attach_target() *before* load phase. If
not, libbpf will report this as an error.

Aslo use SEC_ATTACH_BTF flag instead of explicitly listing a set of
types that are expected to require attach_btf_id. This was an accidental
omission during custom SEC() support refactoring.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 49 +++++++++++++++++++++++++++---------------
 1 file changed, 32 insertions(+), 17 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e840e48d3a76..c9aa5b1278fc 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -6682,17 +6682,32 @@ static int libbpf_prepare_prog_load(struct bpf_program *prog,
 	if (prog->type == BPF_PROG_TYPE_XDP && (def & SEC_XDP_FRAGS))
 		opts->prog_flags |= BPF_F_XDP_HAS_FRAGS;
 
-	if (def & SEC_DEPRECATED)
+	if (def & SEC_DEPRECATED) {
 		pr_warn("SEC(\"%s\") is deprecated, please see https://github.com/libbpf/libbpf/wiki/Libbpf-1.0-migration-guide#bpf-program-sec-annotation-deprecations for details\n",
 			prog->sec_name);
+	}
 
-	if ((prog->type == BPF_PROG_TYPE_TRACING ||
-	     prog->type == BPF_PROG_TYPE_LSM ||
-	     prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) {
+	if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) {
 		int btf_obj_fd = 0, btf_type_id = 0, err;
 		const char *attach_name;
 
-		attach_name = strchr(prog->sec_name, '/') + 1;
+		attach_name = strchr(prog->sec_name, '/');
+		if (!attach_name) {
+			/* if BPF program is annotated with just SEC("fentry")
+			 * (or similar) without declaratively specifying
+			 * target, then it is expected that target will be
+			 * specified with bpf_program__set_attach_target() at
+			 * runtime before BPF object load step. If not, then
+			 * there is nothing to load into the kernel as BPF
+			 * verifier won't be able to validate BPF program
+			 * correctness anyways.
+			 */
+			pr_warn("prog '%s': no BTF-based attach target is specified, use bpf_program__set_attach_target()\n",
+				prog->name);
+			return -EINVAL;
+		}
+		attach_name++; /* skip over / */
+
 		err = libbpf_find_attach_btf_id(prog, attach_name, &btf_obj_fd, &btf_type_id);
 		if (err)
 			return err;
@@ -8869,18 +8884,18 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("raw_tp+",		RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
 	SEC_DEF("raw_tracepoint.w+",	RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
 	SEC_DEF("raw_tp.w+",		RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
-	SEC_DEF("tp_btf/",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
-	SEC_DEF("fentry/",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
-	SEC_DEF("fmod_ret/",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
-	SEC_DEF("fexit/",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF, attach_trace),
-	SEC_DEF("fentry.s/",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
-	SEC_DEF("fmod_ret.s/",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
-	SEC_DEF("fexit.s/",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
-	SEC_DEF("freplace/",		EXT, 0, SEC_ATTACH_BTF, attach_trace),
-	SEC_DEF("lsm/",			LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
-	SEC_DEF("lsm.s/",		LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
-	SEC_DEF("iter/",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF, attach_iter),
-	SEC_DEF("iter.s/",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_iter),
+	SEC_DEF("tp_btf+",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fentry+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fmod_ret+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fexit+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("fentry.s+",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("fmod_ret.s+",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("fexit.s+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
+	SEC_DEF("freplace+",		EXT, 0, SEC_ATTACH_BTF, attach_trace),
+	SEC_DEF("lsm+",			LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
+	SEC_DEF("lsm.s+",		LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
+	SEC_DEF("iter+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF, attach_iter),
+	SEC_DEF("iter.s+",		TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_iter),
 	SEC_DEF("syscall",		SYSCALL, 0, SEC_SLEEPABLE),
 	SEC_DEF("xdp.frags/devmap",	XDP, BPF_XDP_DEVMAP, SEC_XDP_FRAGS),
 	SEC_DEF("xdp/devmap",		XDP, BPF_XDP_DEVMAP, SEC_ATTACHABLE),
-- 
2.30.2

[PATCH v2 bpf-next 3/3] selftests/bpf: use target-less SEC() definitions in various tests

[Andrii Nakryiko]

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.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 .../selftests/bpf/prog_tests/attach_probe.c   | 10 ++++++++
 .../bpf/prog_tests/kprobe_multi_test.c        | 14 +++++------
 .../selftests/bpf/progs/kprobe_multi.c        | 14 +++++++++++
 .../selftests/bpf/progs/test_attach_probe.c   | 23 ++++++++++++++++---
 .../selftests/bpf/progs/test_module_attach.c  |  2 +-
 5 files changed, 52 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
index c0c6d410751d..08c0601b3e84 100644
--- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
+++ b/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");
diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index b9876b55fc0c..c56db65d4c15 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/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;
diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi.c b/tools/testing/selftests/bpf/progs/kprobe_multi.c
index 600be50800f8..93510f4f0f3a 100644
--- a/tools/testing/selftests/bpf/progs/kprobe_multi.c
+++ b/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;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_attach_probe.c b/tools/testing/selftests/bpf/progs/test_attach_probe.c
index af994d16bb10..ce9acf4db8d2 100644
--- a/tools/testing/selftests/bpf/progs/test_attach_probe.c
+++ b/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)
 {
diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c
index 50ce16d02da7..08628afedb77 100644
--- a/tools/testing/selftests/bpf/progs/test_module_attach.c
+++ b/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)
-- 
2.30.2

Re: [PATCH v2 bpf-next 0/3] Add target-less tracing SEC() definitions

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:

On Thu, 28 Apr 2022 11:53:46 -0700 you wrote:
> Allow specifying "target-less" SEC() definitions for tracing BPF programs,
> both non-BTF-backed (kprobes, tracepoints, raw tracepoints) and BTF-backed
> (fentry/fexit, iter, lsm, etc).
> 
> There are various situations where attach target cannot be known at
> compilation time, so libbpf's insistence on specifying something leads to
> users having to add random test like SEC("kprobe/whatever") and then
> specifying correct target at runtime using APIs like
> bpf_program__attach_kprobe().
> 
> [...]

Here is the summary with links:
  - [v2,bpf-next,1/3] libbpf: allow "incomplete" basic tracing SEC() definitions
    https://git.kernel.org/bpf/bpf-next/c/9af8efc45eb1
  - [v2,bpf-next,2/3] libbpf: support target-less SEC() definitions for BTF-backed programs
    https://git.kernel.org/bpf/bpf-next/c/cc7d8f2c8ecc
  - [v2,bpf-next,3/3] selftests/bpf: use target-less SEC() definitions in various tests
    https://git.kernel.org/bpf/bpf-next/c/32c03c4954a0

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html