[PATCH bpf-next v8 0/4] Add prog_kfunc feature probe

[PATCH bpf-next v8 0/4] Add prog_kfunc feature probe

[Tao Chen]

More and more kfunc functions are being added to the kernel.
Different prog types have different restrictions when using kfunc.
Therefore, prog_kfunc probe is added to check whether it is supported,
and the use of this api will be added to bpftool later.

Change list:
- v7 -> v8:
  - fix "kfuncs require device-bound" verifier info
  - add test_libbpf_probe_kfuncs_many test case Co-developed-by 
    Eduard
  - patchset Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
- v7
  https://lore.kernel.org/bpf/20250212153912.24116-1-chen.dylane@gmail.com/  

- v6 -> v7:
  - wrap err with libbpf_err
  - comments fix
  - handle btf_fd < 0 as vmlinux
  - patchset Reviewed-by: Jiri Olsa <jolsa@kernel.org>
- v6
  https://lore.kernel.org/bpf/20250211111859.6029-1-chen.dylane@gmail.com

- v5 -> v6:
  - remove fd_array_cnt
  - test case clean code
- v5
  https://lore.kernel.org/bpf/20250210055945.27192-1-chen.dylane@gmail.com

- v4 -> v5:
  - use fd_array on stack
  - declare the scope of use of btf_fd
- v4
  https://lore.kernel.org/bpf/20250206051557.27913-1-chen.dylane@gmail.com/

- v3 -> v4:
  - add fd_array init for kfunc in mod btf
  - add test case for kfunc in mod btf
  - refactor common part as prog load type check for
    libbpf_probe_bpf_{helper,kfunc}
- v3
  https://lore.kernel.org/bpf/20250124144411.13468-1-chen.dylane@gmail.com

- v2 -> v3:
  - rename parameter off with btf_fd
  - extract the common part for libbpf_probe_bpf_{helper,kfunc}
- v2
  https://lore.kernel.org/bpf/20250123170555.291896-1-chen.dylane@gmail.com

- v1 -> v2:
  - check unsupported prog type like probe_bpf_helper
  - add off parameter for module btf
  - check verifier info when kfunc id invalid
- v1
  https://lore.kernel.org/bpf/20250122171359.232791-1-chen.dylane@gmail.com

Tao Chen (4):
  libbpf: Extract prog load type check from libbpf_probe_bpf_helper
  libbpf: Init fd_array when prog probe load
  libbpf: Add libbpf_probe_bpf_kfunc API
  selftests/bpf: Add libbpf_probe_bpf_kfunc API selftests

 tools/lib/bpf/libbpf.h                        |  19 +-
 tools/lib/bpf/libbpf.map                      |   1 +
 tools/lib/bpf/libbpf_probes.c                 |  89 +++++++--
 .../selftests/bpf/prog_tests/libbpf_probes.c  | 173 ++++++++++++++++++
 4 files changed, 266 insertions(+), 16 deletions(-)

-- 
2.43.0

[PATCH bpf-next v8 1/4] libbpf: Extract prog load type check from libbpf_probe_bpf_helper

[Tao Chen]

Extract prog load type check part from libbpf_probe_bpf_helper
suggested by Andrii, which will be used in both
libbpf_probe_bpf_{helper, kfunc}.

Cc: Tao Chen <dylane.chen@didiglobal.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 tools/lib/bpf/libbpf_probes.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 9dfbe7750f56..a48a557314f6 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -413,6 +413,23 @@ int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
 	return libbpf_err(ret);
 }
 
+static bool can_probe_prog_type(enum bpf_prog_type prog_type)
+{
+	/* we can't successfully load all prog types to check for BPF helper
+	 * and kfunc support.
+	 */
+	switch (prog_type) {
+	case BPF_PROG_TYPE_TRACING:
+	case BPF_PROG_TYPE_EXT:
+	case BPF_PROG_TYPE_LSM:
+	case BPF_PROG_TYPE_STRUCT_OPS:
+		return false;
+	default:
+		break;
+	}
+	return true;
+}
+
 int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
 			    const void *opts)
 {
@@ -427,18 +444,8 @@ int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helpe
 	if (opts)
 		return libbpf_err(-EINVAL);
 
-	/* we can't successfully load all prog types to check for BPF helper
-	 * support, so bail out with -EOPNOTSUPP error
-	 */
-	switch (prog_type) {
-	case BPF_PROG_TYPE_TRACING:
-	case BPF_PROG_TYPE_EXT:
-	case BPF_PROG_TYPE_LSM:
-	case BPF_PROG_TYPE_STRUCT_OPS:
-		return -EOPNOTSUPP;
-	default:
-		break;
-	}
+	if (!can_probe_prog_type(prog_type))
+		return libbpf_err(-EOPNOTSUPP);
 
 	buf[0] = '\0';
 	ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
-- 
2.43.0

[PATCH bpf-next v8 2/4] libbpf: Init fd_array when prog probe load

[Tao Chen]

fd_array used to store module btf fd, which will
be used for kfunc probe in module btf.

Cc: Tao Chen <dylane.chen@didiglobal.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 tools/lib/bpf/libbpf_probes.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index a48a557314f6..de2b1205b436 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -102,12 +102,13 @@ __u32 get_kernel_version(void)
 
 static int probe_prog_load(enum bpf_prog_type prog_type,
 			   const struct bpf_insn *insns, size_t insns_cnt,
-			   char *log_buf, size_t log_buf_sz)
+			   int *fd_array, char *log_buf, size_t log_buf_sz)
 {
 	LIBBPF_OPTS(bpf_prog_load_opts, opts,
 		.log_buf = log_buf,
 		.log_size = log_buf_sz,
 		.log_level = log_buf ? 1 : 0,
+		.fd_array = fd_array,
 	);
 	int fd, err, exp_err = 0;
 	const char *exp_msg = NULL;
@@ -214,7 +215,7 @@ int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
 	if (opts)
 		return libbpf_err(-EINVAL);
 
-	ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0);
+	ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, NULL, 0);
 	return libbpf_err(ret);
 }
 
@@ -448,7 +449,7 @@ int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helpe
 		return libbpf_err(-EOPNOTSUPP);
 
 	buf[0] = '\0';
-	ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
+	ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, buf, sizeof(buf));
 	if (ret < 0)
 		return libbpf_err(ret);
 
-- 
2.43.0

[PATCH bpf-next v8 3/4] libbpf: Add libbpf_probe_bpf_kfunc API

[Tao Chen]

Similarly to libbpf_probe_bpf_helper, the libbpf_probe_bpf_kfunc
used to test the availability of the different eBPF kfuncs on the
current system.

Cc: Tao Chen <dylane.chen@didiglobal.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 tools/lib/bpf/libbpf.h        | 19 ++++++++++++-
 tools/lib/bpf/libbpf.map      |  1 +
 tools/lib/bpf/libbpf_probes.c | 51 +++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 3020ee45303a..c79b4475b956 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1680,7 +1680,24 @@ LIBBPF_API int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void
  */
 LIBBPF_API int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type,
 				       enum bpf_func_id helper_id, const void *opts);
-
+/**
+ * @brief **libbpf_probe_bpf_kfunc()** detects if host kernel supports the
+ * use of a given BPF kfunc from specified BPF program type.
+ * @param prog_type BPF program type used to check the support of BPF kfunc
+ * @param kfunc_id The btf ID of BPF kfunc to check support for
+ * @param btf_fd The module BTF FD, if kfunc is defined in kernel module,
+ * btf_fd is used to point to module's BTF, which is >= 0, and < 0 means kfunc
+ * defined in vmlinux.
+ * @param opts reserved for future extensibility, should be NULL
+ * @return 1, if given combination of program type and kfunc is supported; 0,
+ * if the combination is not supported; negative error code if feature
+ * detection for provided input arguments failed or can't be performed
+ *
+ * Make sure the process has required set of CAP_* permissions (or runs as
+ * root) when performing feature checking.
+ */
+LIBBPF_API int libbpf_probe_bpf_kfunc(enum bpf_prog_type prog_type,
+				      int kfunc_id, int btf_fd, const void *opts);
 /**
  * @brief **libbpf_num_possible_cpus()** is a helper function to get the
  * number of possible CPUs that the host kernel supports and expects.
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index b5a838de6f47..3bbfe13aeb6a 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -438,4 +438,5 @@ LIBBPF_1.6.0 {
 		bpf_linker__new_fd;
 		btf__add_decl_attr;
 		btf__add_type_attr;
+		libbpf_probe_bpf_kfunc;
 } LIBBPF_1.5.0;
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index de2b1205b436..8efebc18a215 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -431,6 +431,57 @@ static bool can_probe_prog_type(enum bpf_prog_type prog_type)
 	return true;
 }
 
+int libbpf_probe_bpf_kfunc(enum bpf_prog_type prog_type, int kfunc_id, int btf_fd,
+			   const void *opts)
+{
+	struct bpf_insn insns[] = {
+		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 1, kfunc_id),
+		BPF_EXIT_INSN(),
+	};
+	const size_t insn_cnt = ARRAY_SIZE(insns);
+	char buf[4096];
+	int fd_array[2] = {-1};
+	int ret;
+
+	if (opts)
+		return libbpf_err(-EINVAL);
+
+	if (!can_probe_prog_type(prog_type))
+		return libbpf_err(-EOPNOTSUPP);
+
+	if (btf_fd >= 0)
+		fd_array[1] = btf_fd;
+	else
+		/* insn.off = 0, means vmlinux btf */
+		insns[0].off = 0;
+
+	buf[0] = '\0';
+	ret = probe_prog_load(prog_type, insns, insn_cnt, btf_fd >= 0 ? fd_array : NULL,
+			      buf, sizeof(buf));
+	if (ret < 0)
+		return libbpf_err(ret);
+
+	if (ret > 0)
+		return 1; /* assume supported */
+
+	/* If BPF verifier recognizes BPF kfunc but it's not supported for
+	 * given BPF program type, it will emit "calling kernel function
+	 * <name> is not allowed". If the kfunc id is invalid,
+	 * it will emit "kernel btf_id <id> is not a function". If BTF fd
+	 * invalid in module BTF, it will emit "invalid module BTF fd specified" or
+	 * "negative offset disallowed for kernel module function call". If
+	 * kfunc prog not dev buound, it will emit "metadata kfuncs require
+	 * device-bound program".
+	 */
+	if (strstr(buf, "not allowed") || strstr(buf, "not a function") ||
+	   strstr(buf, "invalid module BTF fd") ||
+	   strstr(buf, "negative offset disallowed") ||
+	   strstr(buf, "device-bound program"))
+		return 0;
+
+	return 1;
+}
+
 int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
 			    const void *opts)
 {
-- 
2.43.0

[PATCH bpf-next v8 4/4] selftests/bpf: Add libbpf_probe_bpf_kfunc API selftests

[Tao Chen]

Add selftests for prog_kfunc feature probing. Thanks for
Eduard providing the libbpf_probe_func_many test case.

 ./test_progs -t libbpf_probe_kfuncs
 #153     libbpf_probe_kfuncs:OK
 Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

 ./test_progs -t libbpf_probe_kfuncs_many
 #154     libbpf_probe_kfuncs_many:OK
 Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Cc: Tao Chen <dylane.chen@didiglobal.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Co-developed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 .../selftests/bpf/prog_tests/libbpf_probes.c  | 173 ++++++++++++++++++
 1 file changed, 173 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
index 4ed46ed58a7b..db408fd67add 100644
--- a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
+++ b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
@@ -126,3 +126,176 @@ void test_libbpf_probe_helpers(void)
 		ASSERT_EQ(res, d->supported, buf);
 	}
 }
+
+static int module_btf_fd(char *module)
+{
+	int fd, err;
+	__u32 id = 0, len;
+	struct bpf_btf_info info;
+	char name[64];
+
+	while (true) {
+		err = bpf_btf_get_next_id(id, &id);
+		if (err)
+			return -1;
+
+		fd = bpf_btf_get_fd_by_id(id);
+		if (fd < 0) {
+			if (errno == ENOENT)
+				continue;
+			return -1;
+		}
+		len = sizeof(info);
+		memset(&info, 0, sizeof(info));
+		info.name = ptr_to_u64(name);
+		info.name_len = sizeof(name);
+		err = bpf_btf_get_info_by_fd(fd, &info, &len);
+		if (err) {
+			close(fd);
+			return -1;
+		}
+		/* find target module BTF */
+		if (!strcmp(name, module))
+			break;
+
+		close(fd);
+	}
+
+	return fd;
+}
+
+void test_libbpf_probe_kfuncs(void)
+{
+	int ret, kfunc_id, fd;
+	char *kfunc = "bpf_cpumask_create";
+	struct btf *vmlinux_btf = NULL;
+	struct btf *module_btf = NULL;
+
+	vmlinux_btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
+	if (!ASSERT_OK_PTR(vmlinux_btf, "btf_parse"))
+		return;
+
+	kfunc_id = btf__find_by_name_kind(vmlinux_btf, kfunc, BTF_KIND_FUNC);
+	if (!ASSERT_GT(kfunc_id, 0, kfunc))
+		goto cleanup;
+
+	/* prog BPF_PROG_TYPE_SYSCALL supports kfunc bpf_cpumask_create */
+	ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, kfunc_id, -1, NULL);
+	if (!ASSERT_EQ(ret, 1, "kfunc in vmlinux support"))
+		goto cleanup;
+
+	/* prog BPF_PROG_TYPE_KPROBE does not support kfunc bpf_cpumask_create */
+	ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_KPROBE, kfunc_id, -1, NULL);
+	if (!ASSERT_EQ(ret, 0, "kfunc in vmlinux not suuport"))
+		goto cleanup;
+
+	ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_KPROBE, -1, -1, NULL);
+	if (!ASSERT_EQ(ret, 0, "invalid kfunc id:-1"))
+		goto cleanup;
+
+	ret = libbpf_probe_bpf_kfunc(100000, kfunc_id, -1, NULL);
+	if (!ASSERT_ERR(ret, "invalid prog type:100000"))
+		goto cleanup;
+
+	if (!env.has_testmod)
+		goto cleanup;
+
+	module_btf = btf__load_module_btf("bpf_testmod", vmlinux_btf);
+	if (!ASSERT_OK_PTR(module_btf, "load module BTF"))
+		goto cleanup;
+
+	kfunc_id = btf__find_by_name(module_btf, "bpf_kfunc_call_test1");
+	if (!ASSERT_GT(kfunc_id, 0, "func not found"))
+		goto cleanup;
+
+	fd = module_btf_fd("bpf_testmod");
+	if (!ASSERT_GE(fd, 0, "module BTF fd"))
+		goto cleanup;
+
+	/* prog BPF_PROG_TYPE_SYSCALL supports kfunc bpf_kfunc_call_test1 in bpf_testmod */
+	ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, kfunc_id, fd, NULL);
+	if (!ASSERT_EQ(ret, 1, "kfunc in module BTF support"))
+		goto cleanup_fd;
+
+	/* prog BPF_PROG_TYPE_KPROBE does not support kfunc bpf_kfunc_call_test1
+	 * in bpf_testmod
+	 */
+	ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_KPROBE, kfunc_id, fd, NULL);
+	if (!ASSERT_EQ(ret, 0, "kfunc in module BTF not support"))
+		goto cleanup_fd;
+
+	ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, -1, fd, NULL);
+	if (!ASSERT_EQ(ret, 0, "invalid kfunc id in module BTF"))
+		goto cleanup_fd;
+
+	ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, kfunc_id, 100, NULL);
+	ASSERT_EQ(ret, 0, "invalid BTF fd in module BTF");
+
+cleanup_fd:
+	close(fd);
+cleanup:
+	btf__free(vmlinux_btf);
+	btf__free(module_btf);
+}
+
+static const struct {
+	const char *name;
+	int code;
+} program_types[] = {
+#define _T(n) { #n, BPF_PROG_TYPE_##n }
+	_T(KPROBE),
+	_T(XDP),
+	_T(SYSCALL),
+	_T(SCHED_CLS),
+	_T(SCHED_ACT),
+	_T(SK_SKB),
+	_T(SOCKET_FILTER),
+	_T(CGROUP_SKB),
+	_T(LWT_OUT),
+	_T(LWT_IN),
+	_T(LWT_XMIT),
+	_T(LWT_SEG6LOCAL),
+	_T(NETFILTER),
+	_T(CGROUP_SOCK_ADDR),
+	_T(SCHED_ACT)
+#undef _T
+};
+
+void test_libbpf_probe_kfuncs_many(void)
+{
+	int i, kfunc_id, ret, id;
+	const struct btf_type *t;
+	struct btf *btf = NULL;
+	const char *kfunc;
+	const char *tag;
+
+	btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
+	if (!ASSERT_OK_PTR(btf, "btf_parse"))
+		return;
+	for (id = 0; id < btf__type_cnt(btf); ++id) {
+		t = btf__type_by_id(btf, id);
+		if (!t)
+			continue;
+		if (!btf_is_decl_tag(t))
+			continue;
+		tag = btf__name_by_offset(btf, t->name_off);
+		if (strcmp(tag, "bpf_kfunc") != 0)
+			continue;
+		kfunc_id = t->type;
+		t = btf__type_by_id(btf, kfunc_id);
+		if (!btf_is_func(t))
+			continue;
+		kfunc = btf__name_by_offset(btf, t->name_off);
+		for (i = 0; i < ARRAY_SIZE(program_types); ++i) {
+			ret = libbpf_probe_bpf_kfunc(program_types[i].code,
+						     kfunc_id, -1, NULL);
+			if (ret < 0) {
+				ASSERT_FAIL("kfunc:%s use prog type:%d",
+				      kfunc, program_types[i].code);
+				goto cleanup;
+			}
+		}
+	}
+cleanup:
+	btf__free(btf);
+}
-- 
2.43.0

Re: [PATCH bpf-next v8 4/4] selftests/bpf: Add libbpf_probe_bpf_kfunc API selftests

[Eduard Zingerman]

On Sat, 2025-02-22 at 00:33 +0800, Tao Chen wrote:

[...]

> +static const struct {
> +	const char *name;
> +	int code;
> +} program_types[] = {
> +#define _T(n) { #n, BPF_PROG_TYPE_##n }
> +	_T(KPROBE),
> +	_T(XDP),
> +	_T(SYSCALL),
> +	_T(SCHED_CLS),
> +	_T(SCHED_ACT),
> +	_T(SK_SKB),
> +	_T(SOCKET_FILTER),
> +	_T(CGROUP_SKB),
> +	_T(LWT_OUT),
> +	_T(LWT_IN),
> +	_T(LWT_XMIT),
> +	_T(LWT_SEG6LOCAL),
> +	_T(NETFILTER),
> +	_T(CGROUP_SOCK_ADDR),
> +	_T(SCHED_ACT)
> +#undef _T
> +};
> +
> +void test_libbpf_probe_kfuncs_many(void)
> +{

Hi Tao,

Sorry, probably some miscommunication from my side.
I did not mean this test for inclusion, it was meant as a one time
manual inspection of libbpf_probe_bpf_kfunc results.
Just as a sanity check before series is merged.
As an automated test it does not provide much meaningful signal.

> +	int i, kfunc_id, ret, id;
> +	const struct btf_type *t;
> +	struct btf *btf = NULL;
> +	const char *kfunc;
> +	const char *tag;
> +
> +	btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
> +	if (!ASSERT_OK_PTR(btf, "btf_parse"))
> +		return;
> +	for (id = 0; id < btf__type_cnt(btf); ++id) {
> +		t = btf__type_by_id(btf, id);
> +		if (!t)
> +			continue;
> +		if (!btf_is_decl_tag(t))
> +			continue;
> +		tag = btf__name_by_offset(btf, t->name_off);
> +		if (strcmp(tag, "bpf_kfunc") != 0)
> +			continue;
> +		kfunc_id = t->type;
> +		t = btf__type_by_id(btf, kfunc_id);
> +		if (!btf_is_func(t))
> +			continue;
> +		kfunc = btf__name_by_offset(btf, t->name_off);
> +		for (i = 0; i < ARRAY_SIZE(program_types); ++i) {
> +			ret = libbpf_probe_bpf_kfunc(program_types[i].code,
> +						     kfunc_id, -1, NULL);
> +			if (ret < 0) {
> +				ASSERT_FAIL("kfunc:%s use prog type:%d",
> +				      kfunc, program_types[i].code);
> +				goto cleanup;
> +			}
> +		}
> +	}
> +cleanup:
> +	btf__free(btf);
> +}

Re: [PATCH bpf-next v8 4/4] selftests/bpf: Add libbpf_probe_bpf_kfunc API selftests

[Tao Chen]

在 2025/2/22 02:19, Eduard Zingerman 写道:
> On Sat, 2025-02-22 at 00:33 +0800, Tao Chen wrote:
> 
> [...]
> 
>> +static const struct {
>> +	const char *name;
>> +	int code;
>> +} program_types[] = {
>> +#define _T(n) { #n, BPF_PROG_TYPE_##n }
>> +	_T(KPROBE),
>> +	_T(XDP),
>> +	_T(SYSCALL),
>> +	_T(SCHED_CLS),
>> +	_T(SCHED_ACT),
>> +	_T(SK_SKB),
>> +	_T(SOCKET_FILTER),
>> +	_T(CGROUP_SKB),
>> +	_T(LWT_OUT),
>> +	_T(LWT_IN),
>> +	_T(LWT_XMIT),
>> +	_T(LWT_SEG6LOCAL),
>> +	_T(NETFILTER),
>> +	_T(CGROUP_SOCK_ADDR),
>> +	_T(SCHED_ACT)
>> +#undef _T
>> +};
>> +
>> +void test_libbpf_probe_kfuncs_many(void)
>> +{
> 
> Hi Tao,
> 
> Sorry, probably some miscommunication from my side.
> I did not mean this test for inclusion, it was meant as a one time
> manual inspection of libbpf_probe_bpf_kfunc results.
> Just as a sanity check before series is merged.
> As an automated test it does not provide much meaningful signal.
> 

Ok, i will resend v8 without this case, and check all the prog types 
later with your program. Thanks.

>> +	int i, kfunc_id, ret, id;
>> +	const struct btf_type *t;
>> +	struct btf *btf = NULL;
>> +	const char *kfunc;
>> +	const char *tag;
>> +
>> +	btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
>> +	if (!ASSERT_OK_PTR(btf, "btf_parse"))
>> +		return;
>> +	for (id = 0; id < btf__type_cnt(btf); ++id) {
>> +		t = btf__type_by_id(btf, id);
>> +		if (!t)
>> +			continue;
>> +		if (!btf_is_decl_tag(t))
>> +			continue;
>> +		tag = btf__name_by_offset(btf, t->name_off);
>> +		if (strcmp(tag, "bpf_kfunc") != 0)
>> +			continue;
>> +		kfunc_id = t->type;
>> +		t = btf__type_by_id(btf, kfunc_id);
>> +		if (!btf_is_func(t))
>> +			continue;
>> +		kfunc = btf__name_by_offset(btf, t->name_off);
>> +		for (i = 0; i < ARRAY_SIZE(program_types); ++i) {
>> +			ret = libbpf_probe_bpf_kfunc(program_types[i].code,
>> +						     kfunc_id, -1, NULL);
>> +			if (ret < 0) {
>> +				ASSERT_FAIL("kfunc:%s use prog type:%d",
>> +				      kfunc, program_types[i].code);
>> +				goto cleanup;
>> +			}
>> +		}
>> +	}
>> +cleanup:
>> +	btf__free(btf);
>> +}
> 
> 


-- 
Best Regards
Tao Chen