[RFC PATCH 05/13] bpf tools: Save engine type in bpf_program

[Wang Nan]

Add an 'engine' field in bpf_program to indicate whether a program is a
ubpf program or kernel bpf program. For compatibility, the default
engine is kernel bpf, unless explicitly set to ubpf using
bpf_program__set_ubpf().

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
---
 tools/lib/bpf/libbpf.c | 40 ++++++++++++++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.h |  4 ++++
 2 files changed, 44 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index dd5a107..3755846 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -80,6 +80,7 @@ static const char *libbpf_strerror_table[NR_ERRNO] = {
 	[ERRCODE_OFFSET(VERIFY)]	= "Kernel verifier blocks program loading",
 	[ERRCODE_OFFSET(PROG2BIG)]	= "Program too big",
 	[ERRCODE_OFFSET(KVER)]		= "Incorrect kernel version",
+	[ERRCODE_OFFSET(NOUBPF)]	= "UBPF support is not compiled",
 };
 
 int libbpf_strerror(int err, char *buf, size_t size)
@@ -147,6 +148,11 @@ union prog_instance {
  * linux/filter.h.
  */
 struct bpf_program {
+	enum {
+		ENGINE_UNKNOWN,
+		ENGINE_KBPF,
+		ENGINE_UBPF,
+	} engine;
 	/* Index in elf obj file, for relocation use. */
 	int idx;
 	char *section_name;
@@ -291,6 +297,7 @@ bpf_program__init(void *data, size_t size, char *name, int idx,
 	memcpy(prog->insns, data,
 	       prog->insns_cnt * sizeof(struct bpf_insn));
 	prog->idx = idx;
+	prog->engine = ENGINE_UNKNOWN;
 	prog->instances.array = NULL;
 	prog->instances.nr = -1;
 
@@ -941,6 +948,11 @@ bpf_program__load(struct bpf_program *prog,
 {
 	int err = 0, fd, i;
 
+	if (prog->engine == ENGINE_UNKNOWN)
+		prog->engine = ENGINE_KBPF;
+	if (prog->engine != ENGINE_KBPF)
+		return -EINVAL;
+
 	if (prog->instances.nr < 0 || !prog->instances.array) {
 		if (prog->preprocessor) {
 			pr_warning("Internal error: can't load program '%s'\n",
@@ -1318,6 +1330,34 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)
 	return fd;
 }
 
+#ifdef HAVE_UBPF_SUPPORT
+int bpf_program__set_ubpf(struct bpf_program *prog)
+{
+	if (prog->engine != ENGINE_UNKNOWN) {
+		pr_warning("Can't set program %s to ubpf\n",
+			   prog->section_name);
+		return -EINVAL;
+	}
+	prog->engine = ENGINE_UBPF;
+	return 0;
+}
+
+bool bpf_program__is_ubpf(struct bpf_program *prog)
+{
+	return prog->engine == ENGINE_UBPF;
+}
+#else
+int bpf_program__set_ubpf(struct bpf_program *prog __maybe_unused)
+{
+	return -LIBBPF_ERRNO__NOUBPF;
+}
+
+bool bpf_program__is_ubpf(struct bpf_program *prog __maybe_unused)
+{
+	return false;
+}
+#endif
+
 int bpf_map__get_fd(struct bpf_map *map)
 {
 	if (!map)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index a51594c..f6965ce 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -26,6 +26,7 @@ enum libbpf_errno {
 	LIBBPF_ERRNO__VERIFY,	/* Kernel verifier blocks program loading */
 	LIBBPF_ERRNO__PROG2BIG,	/* Program too big */
 	LIBBPF_ERRNO__KVER,	/* Incorrect kernel version */
+	LIBBPF_ERRNO__NOUBPF,	/* UBPF support is not compiled */
 	__LIBBPF_ERRNO__END,
 };
 
@@ -86,6 +87,9 @@ int bpf_program__get_private(struct bpf_program *prog,
 
 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy);
 
+int bpf_program__set_ubpf(struct bpf_program *prog);
+bool bpf_program__is_ubpf(struct bpf_program *prog);
+
 int bpf_program__fd(struct bpf_program *prog);
 
 struct bpf_insn;
-- 
1.8.3.4