bpf tools: Introduce accessors for struct bpf_program

This patch introduces accessors for user of libbpf to retrieve section
name and fd of a opened/loaded eBPF program. 'struct bpf_prog_handler'
is used for that purpose. Accessors of programs section name and file
descriptor are provided. Set/get private data are also impelmented.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1435716878-189507-21-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 96 insertions, 0 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 38447b7d6e73..ae1c5cbd8158 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -98,6 +98,10 @@ struct bpf_program {
         int nr_reloc;
 
         int fd;
+
+        struct bpf_object *obj;
+        void *priv;
+        bpf_program_clear_priv_t clear_priv;
 };
 
 struct bpf_object {
@@ -150,6 +154,12 @@ static void bpf_program__exit(struct bpf_program *prog)
         if (!prog)
                 return;
 
+        if (prog->clear_priv)
+                prog->clear_priv(prog, prog->priv);
+
+        prog->priv = NULL;
+        prog->clear_priv = NULL;
+
         bpf_program__unload(prog);
         zfree(&prog->section_name);
         zfree(&prog->insns);
@@ -225,6 +235,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
         pr_debug("found program %s\n", prog.section_name);
         obj->programs = progs;
         obj->nr_programs = nr_progs + 1;
+        prog.obj = obj;
         progs[nr_progs] = prog;
         return 0;
 }
@@ -931,3 +942,64 @@ void bpf_object__close(struct bpf_object *obj)
 
         free(obj);
 }
+
+struct bpf_program *
+bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
+{
+        size_t idx;
+
+        if (!obj->programs)
+                return NULL;
+        /* First handler */
+        if (prev == NULL)
+                return &obj->programs[0];
+
+        if (prev->obj != obj) {
+                pr_warning("error: program handler doesn't match object\n");
+                return NULL;
+        }
+
+        idx = (prev - obj->programs) + 1;
+        if (idx >= obj->nr_programs)
+                return NULL;
+        return &obj->programs[idx];
+}
+
+int bpf_program__set_private(struct bpf_program *prog,
+                             void *priv,
+                             bpf_program_clear_priv_t clear_priv)
+{
+        if (prog->priv && prog->clear_priv)
+                prog->clear_priv(prog, prog->priv);
+
+        prog->priv = priv;
+        prog->clear_priv = clear_priv;
+        return 0;
+}
+
+int bpf_program__get_private(struct bpf_program *prog, void **ppriv)
+{
+        *ppriv = prog->priv;
+        return 0;
+}
+
+const char *bpf_program__title(struct bpf_program *prog, bool dup)
+{
+        const char *title;
+
+        title = prog->section_name;
+        if (dup) {
+                title = strdup(title);
+                if (!title) {
+                        pr_warning("failed to strdup program title\n");
+                        return NULL;
+                }
+        }
+
+        return title;
+}
+
+int bpf_program__fd(struct bpf_program *prog)
+{
+        return prog->fd;
+}
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 3e6960075835..657e497bd586 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -9,6 +9,7 @@
 #define __BPF_LIBBPF_H
 
 #include <stdio.h>
+#include <stdbool.h>
 
 /*
  * In include/linux/compiler-gcc.h, __printf is defined. However
@@ -34,6 +35,29 @@ void bpf_object__close(struct bpf_object *object);
 int bpf_object__load(struct bpf_object *obj);
 int bpf_object__unload(struct bpf_object *obj);
 
+/* Accessors of bpf_program. */
+struct bpf_program;
+struct bpf_program *bpf_program__next(struct bpf_program *prog,
+                                      struct bpf_object *obj);
+
+#define bpf_object__for_each_program(pos, obj)          \
+        for ((pos) = bpf_program__next(NULL, (obj));    \
+             (pos) != NULL;                             \
+             (pos) = bpf_program__next((pos), (obj)))
+
+typedef void (*bpf_program_clear_priv_t)(struct bpf_program *,
+                                         void *);
+
+int bpf_program__set_private(struct bpf_program *prog, void *priv,
+                             bpf_program_clear_priv_t clear_priv);
+
+int bpf_program__get_private(struct bpf_program *prog,
+                             void **ppriv);
+
+const char *bpf_program__title(struct bpf_program *prog, bool dup);
+
+int bpf_program__fd(struct bpf_program *prog);
+
 /*
  * We don't need __attribute__((packed)) now since it is
  * unnecessary for 'bpf_map_def' because they are all aligned.