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

From: Wang Nan
Date: Wed Apr 20 2016 - 14:05:00 EST


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