libbpf: Expose BPF program's function name

Add APIs to get BPF program function name, as opposed to bpf_program__title(),
which returns BPF program function's section name. Function name has a benefit
of being a valid C identifier and uniquely identifies a specific BPF program,
while section name can be duplicated across multiple independent BPF programs.

Add also bpf_object__find_program_by_name(), similar to
bpf_object__find_program_by_title(), to facilitate looking up BPF programs by
their C function names.

Convert one of selftests to new API for look up.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191214014341.3442258-9-andriin@fb.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 61b8cdf..e7a6b57 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -209,8 +209,8 @@ static const char * const libbpf_type_to_btf_name[] = {
 };
 
 struct bpf_map {
-       int fd;
        char *name;
+       int fd;
        int sec_idx;
        size_t sec_offset;
        int map_ifindex;
@@ -1384,7 +1384,7 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
 }
 
 static int bpf_object__init_maps(struct bpf_object *obj,
-                                struct bpf_object_open_opts *opts)
+                                const struct bpf_object_open_opts *opts)
 {
        const char *pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
        bool strict = !OPTS_GET(opts, relaxed_maps, false);
@@ -1748,6 +1748,19 @@ bpf_object__find_program_by_title(const struct bpf_object *obj,
        return NULL;
 }
 
+struct bpf_program *
+bpf_object__find_program_by_name(const struct bpf_object *obj,
+                                const char *name)
+{
+       struct bpf_program *prog;
+
+       bpf_object__for_each_program(prog, obj) {
+               if (!strcmp(prog->name, name))
+                       return prog;
+       }
+       return NULL;
+}
+
 static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
                                      int shndx)
 {
@@ -3894,7 +3907,7 @@ static int libbpf_find_attach_btf_id(const char *name,
                                     __u32 attach_prog_fd);
 static struct bpf_object *
 __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
-                  struct bpf_object_open_opts *opts)
+                  const struct bpf_object_open_opts *opts)
 {
        struct bpf_program *prog;
        struct bpf_object *obj;
@@ -4003,7 +4016,7 @@ struct bpf_object *bpf_object__open(const char *path)
 }
 
 struct bpf_object *
-bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts)
+bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts)
 {
        if (!path)
                return ERR_PTR(-EINVAL);
@@ -4015,7 +4028,7 @@ bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts)
 
 struct bpf_object *
 bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
-                    struct bpf_object_open_opts *opts)
+                    const struct bpf_object_open_opts *opts)
 {
        if (!obj_buf || obj_buf_sz == 0)
                return ERR_PTR(-EINVAL);
@@ -4820,6 +4833,11 @@ void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
        prog->prog_ifindex = ifindex;
 }
 
+const char *bpf_program__name(const struct bpf_program *prog)
+{
+       return prog->name;
+}
+
 const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy)
 {
        const char *title;

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 49e6fa0..f37bd4a 100644 (file)
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -90,10 +90,10 @@ struct bpf_object_open_opts {
 
 LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
 LIBBPF_API struct bpf_object *
-bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts);
+bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts);
 LIBBPF_API struct bpf_object *
 bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
-                    struct bpf_object_open_opts *opts);
+                    const struct bpf_object_open_opts *opts);
 
 /* deprecated bpf_object__open variants */
 LIBBPF_API struct bpf_object *
@@ -132,6 +132,7 @@ struct bpf_object_load_attr {
 LIBBPF_API int bpf_object__load(struct bpf_object *obj);
 LIBBPF_API int bpf_object__load_xattr(struct bpf_object_load_attr *attr);
 LIBBPF_API int bpf_object__unload(struct bpf_object *obj);
+
 LIBBPF_API const char *bpf_object__name(const struct bpf_object *obj);
 LIBBPF_API unsigned int bpf_object__kversion(const struct bpf_object *obj);
 
@@ -142,6 +143,9 @@ LIBBPF_API int bpf_object__btf_fd(const struct bpf_object *obj);
 LIBBPF_API struct bpf_program *
 bpf_object__find_program_by_title(const struct bpf_object *obj,
                                  const char *title);
+LIBBPF_API struct bpf_program *
+bpf_object__find_program_by_name(const struct bpf_object *obj,
+                                const char *name);
 
 LIBBPF_API struct bpf_object *bpf_object__next(struct bpf_object *prev);
 #define bpf_object__for_each_safe(pos, tmp)                    \
@@ -185,6 +189,7 @@ LIBBPF_API void *bpf_program__priv(const struct bpf_program *prog);
 LIBBPF_API void bpf_program__set_ifindex(struct bpf_program *prog,
                                         __u32 ifindex);
 
+LIBBPF_API const char *bpf_program__name(const struct bpf_program *prog);
 LIBBPF_API const char *bpf_program__title(const struct bpf_program *prog,
                                          bool needs_copy);
 

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 990c7c0..5a76307 100644 (file)
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -212,6 +212,8 @@ LIBBPF_0.0.6 {
 LIBBPF_0.0.7 {
        global:
                btf_dump__emit_type_decl;
+               bpf_object__find_program_by_name;
                bpf_program__attach;
+               bpf_program__name;
                btf__align_of;
 } LIBBPF_0.0.6;

diff --git a/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c b/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c
index d90acc1..563e121 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c
+++ b/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c
@@ -16,14 +16,11 @@ struct rdonly_map_subtest {
 
 void test_rdonly_maps(void)
 {
-       const char *prog_name_skip_loop = "raw_tracepoint/sys_enter:skip_loop";
-       const char *prog_name_part_loop = "raw_tracepoint/sys_enter:part_loop";
-       const char *prog_name_full_loop = "raw_tracepoint/sys_enter:full_loop";
        const char *file = "test_rdonly_maps.o";
        struct rdonly_map_subtest subtests[] = {
-               { "skip loop", prog_name_skip_loop, 0, 0 },
-               { "part loop", prog_name_part_loop, 3, 2 + 3 + 4 },
-               { "full loop", prog_name_full_loop, 4, 2 + 3 + 4 + 5 },
+               { "skip loop", "skip_loop", 0, 0 },
+               { "part loop", "part_loop", 3, 2 + 3 + 4 },
+               { "full loop", "full_loop", 4, 2 + 3 + 4 + 5 },
        };
        int i, err, zero = 0, duration = 0;
        struct bpf_link *link = NULL;
@@ -50,7 +47,7 @@ void test_rdonly_maps(void)
                if (!test__start_subtest(t->subtest_name))
                        continue;
 
-               prog = bpf_object__find_program_by_title(obj, t->prog_name);
+               prog = bpf_object__find_program_by_name(obj, t->prog_name);
                if (CHECK(!prog, "find_prog", "prog '%s' not found\n",
                          t->prog_name))
                        goto cleanup;