bpf tools: Load eBPF programs in object files into kernel

This patch utilizes previous introduced bpf_load_program to load
programs in the ELF file into kernel. Result is stored in 'fd' field in
'struct bpf_program'.

During loading, it allocs a log buffer and free it before return.  Note
that that buffer is not passed to bpf_load_program() if the first
loading try is successful. Doesn't use a statically allocated log buffer
to avoid potention multi-thread problem.

Instructions collected during opening is cleared after loading.

load_program() is created for loading a 'struct bpf_insn' array into
kernel, bpf_program__load() calls it. By this design we have a function
loads instructions into kernel. It will be used by further patches,
which creates different instances from a program and load them into
kernel.

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>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-20-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 94f9660..38447b7 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -96,6 +96,8 @@ struct bpf_program {
                int map_idx;
        } *reloc_desc;
        int nr_reloc;
+
+       int fd;
 };
 
 struct bpf_object {
@@ -135,11 +137,20 @@ struct bpf_object {
 };
 #define obj_elf_valid(o)       ((o)->efile.elf)
 
+static void bpf_program__unload(struct bpf_program *prog)
+{
+       if (!prog)
+               return;
+
+       zclose(prog->fd);
+}
+
 static void bpf_program__exit(struct bpf_program *prog)
 {
        if (!prog)
                return;
 
+       bpf_program__unload(prog);
        zfree(&prog->section_name);
        zfree(&prog->insns);
        zfree(&prog->reloc_desc);
@@ -176,6 +187,7 @@ 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->fd = -1;
 
        return 0;
 errout:
@@ -718,6 +730,79 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
        return 0;
 }
 
+static int
+load_program(struct bpf_insn *insns, int insns_cnt,
+            char *license, u32 kern_version, int *pfd)
+{
+       int ret;
+       char *log_buf;
+
+       if (!insns || !insns_cnt)
+               return -EINVAL;
+
+       log_buf = malloc(BPF_LOG_BUF_SIZE);
+       if (!log_buf)
+               pr_warning("Alloc log buffer for bpf loader error, continue without log\n");
+
+       ret = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns,
+                              insns_cnt, license, kern_version,
+                              log_buf, BPF_LOG_BUF_SIZE);
+
+       if (ret >= 0) {
+               *pfd = ret;
+               ret = 0;
+               goto out;
+       }
+
+       ret = -EINVAL;
+       pr_warning("load bpf program failed: %s\n", strerror(errno));
+
+       if (log_buf) {
+               pr_warning("-- BEGIN DUMP LOG ---\n");
+               pr_warning("\n%s\n", log_buf);
+               pr_warning("-- END LOG --\n");
+       }
+
+out:
+       free(log_buf);
+       return ret;
+}
+
+static int
+bpf_program__load(struct bpf_program *prog,
+                 char *license, u32 kern_version)
+{
+       int err, fd;
+
+       err = load_program(prog->insns, prog->insns_cnt,
+                          license, kern_version, &fd);
+       if (!err)
+               prog->fd = fd;
+
+       if (err)
+               pr_warning("failed to load program '%s'\n",
+                          prog->section_name);
+       zfree(&prog->insns);
+       prog->insns_cnt = 0;
+       return err;
+}
+
+static int
+bpf_object__load_progs(struct bpf_object *obj)
+{
+       size_t i;
+       int err;
+
+       for (i = 0; i < obj->nr_programs; i++) {
+               err = bpf_program__load(&obj->programs[i],
+                                       obj->license,
+                                       obj->kern_version);
+               if (err)
+                       return err;
+       }
+       return 0;
+}
+
 static int bpf_object__validate(struct bpf_object *obj)
 {
        if (obj->kern_version == 0) {
@@ -795,6 +880,9 @@ int bpf_object__unload(struct bpf_object *obj)
        zfree(&obj->map_fds);
        obj->nr_map_fds = 0;
 
+       for (i = 0; i < obj->nr_programs; i++)
+               bpf_program__unload(&obj->programs[i]);
+
        return 0;
 }
 
@@ -813,6 +901,8 @@ int bpf_object__load(struct bpf_object *obj)
                goto out;
        if (bpf_object__relocate(obj))
                goto out;
+       if (bpf_object__load_progs(obj))
+               goto out;
 
        return 0;
 out: