[tip:perf/urgent] bpf tools: New API to get name from a BPF object

From: tip-bot for Wang Nan
Date: Tue Sep 01 2015 - 04:31:48 EST


Commit-ID: acf860ae7c53cc8b0c5d372c218332aac3eeba4f
Gitweb: http://git.kernel.org/tip/acf860ae7c53cc8b0c5d372c218332aac3eeba4f
Author: Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Thu, 27 Aug 2015 02:30:55 +0000
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 31 Aug 2015 16:53:15 -0300

bpf tools: New API to get name from a BPF object

Before this patch there's no way to connect a loaded bpf object
to its source file. However, during applying perf's '--filter' to BPF
object, without this connection makes things harder, because perf loads
all programs together, but '--filter' setting is for each object.

The API of bpf_object__open_buffer() is changed to allow passing a name.
Fortunately, at this time there's only one user of it (perf test LLVM),
so we change it together.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1440742821-44548-2-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 25 ++++++++++++++++++++++---
tools/lib/bpf/libbpf.h | 4 +++-
tools/perf/tests/llvm.c | 2 +-
3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4fa4bc4..4252fc2 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -880,15 +880,26 @@ struct bpf_object *bpf_object__open(const char *path)
}

struct bpf_object *bpf_object__open_buffer(void *obj_buf,
- size_t obj_buf_sz)
+ size_t obj_buf_sz,
+ const char *name)
{
+ char tmp_name[64];
+
/* param validation */
if (!obj_buf || obj_buf_sz <= 0)
return NULL;

- pr_debug("loading object from buffer\n");
+ if (!name) {
+ snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
+ (unsigned long)obj_buf,
+ (unsigned long)obj_buf_sz);
+ tmp_name[sizeof(tmp_name) - 1] = '\0';
+ name = tmp_name;
+ }
+ pr_debug("loading object '%s' from buffer\n",
+ name);

- return __bpf_object__open("[buffer]", obj_buf, obj_buf_sz);
+ return __bpf_object__open(name, obj_buf, obj_buf_sz);
}

int bpf_object__unload(struct bpf_object *obj)
@@ -975,6 +986,14 @@ bpf_object__next(struct bpf_object *prev)
return next;
}

+const char *
+bpf_object__get_name(struct bpf_object *obj)
+{
+ if (!obj)
+ return NULL;
+ return obj->path;
+}
+
struct bpf_program *
bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
{
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index ea8adc2..f16170c 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -28,12 +28,14 @@ struct bpf_object;

struct bpf_object *bpf_object__open(const char *path);
struct bpf_object *bpf_object__open_buffer(void *obj_buf,
- size_t obj_buf_sz);
+ size_t obj_buf_sz,
+ const char *name);
void bpf_object__close(struct bpf_object *object);

/* Load/unload object into/from kernel */
int bpf_object__load(struct bpf_object *obj);
int bpf_object__unload(struct bpf_object *obj);
+const char *bpf_object__get_name(struct bpf_object *obj);

struct bpf_object *bpf_object__next(struct bpf_object *prev);
#define bpf_object__for_each_safe(pos, tmp) \
diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c
index a337356..52d5597 100644
--- a/tools/perf/tests/llvm.c
+++ b/tools/perf/tests/llvm.c
@@ -26,7 +26,7 @@ static int test__bpf_parsing(void *obj_buf, size_t obj_buf_sz)
{
struct bpf_object *obj;

- obj = bpf_object__open_buffer(obj_buf, obj_buf_sz);
+ obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, NULL);
if (!obj)
return -1;
bpf_object__close(obj);
--
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