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    Subject[tip:perf/core] bpf tools: Introduce accessors for struct bpf_program
    Commit-ID:  aa9b1ac33c7979d0d91eff8b70cffc4916f5555c
    Gitweb: http://git.kernel.org/tip/aa9b1ac33c7979d0d91eff8b70cffc4916f5555c
    Author: Wang Nan <wangnan0@huawei.com>
    AuthorDate: Wed, 1 Jul 2015 02:14:08 +0000
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitDate: Fri, 7 Aug 2015 10:16:59 -0300

    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>
    ---
    tools/lib/bpf/libbpf.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++
    tools/lib/bpf/libbpf.h | 24 +++++++++++++++++
    2 files changed, 96 insertions(+)

    diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
    index 38447b7..ae1c5cb 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 3e69600..657e497 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.

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