On Fri, May 7, 2021 at 8:49 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> Introduce bpf_map__get_initial_value() to read initial contents
> of rodata/bss maps. Note only mmaped maps qualify.
> Just as bpf_map__set_initial_value() works only for mmaped kconfig.
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.c | 10 ++++++++++
> tools/lib/bpf/libbpf.h | 2 ++
> tools/lib/bpf/libbpf.map | 1 +
> 3 files changed, 13 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 24a659448782..f7cdbb0e1faf 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -9763,6 +9763,16 @@ int bpf_map__set_initial_value(struct bpf_map *map,
> return 0;
> }
>
> +int bpf_map__get_initial_value(struct bpf_map *map,
> + const void **pdata, size_t *psize)
the general patterns (there are legacy exceptions) for getters is to
not have "get_" in the name. Please rename it to just
bpf_map__initial_value().
Also btf__get_raw_data() (note the legacy naming) follows a slightly
different pattern of returning NULL on error or valid pointer on
success. And then the size is returned as outer param. Unless there is
a good reason not to, let's be consistent with that pattern?
> +{
> + if (!map->mmaped)
> + return -EINVAL;
> + *psize = map->def.value_size;
> + *pdata = map->mmaped;
> + return 0;
> +}
> +
> bool bpf_map__is_offload_neutral(const struct bpf_map *map)
> {
> return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index fb291b4529e8..f8976a30586f 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -471,6 +471,8 @@ LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv,
> LIBBPF_API void *bpf_map__priv(const struct bpf_map *map);
> LIBBPF_API int bpf_map__set_initial_value(struct bpf_map *map,
> const void *data, size_t size);
> +LIBBPF_API int bpf_map__get_initial_value(struct bpf_map *map,
> + const void **pdata, size_t *psize);
> LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map);
> LIBBPF_API bool bpf_map__is_internal(const struct bpf_map *map);
> LIBBPF_API int bpf_map__set_pin_path(struct bpf_map *map, const char *path);
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 889ee2f3611c..44285045ddf4 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -360,6 +360,7 @@ LIBBPF_0.4.0 {
> bpf_linker__free;
> bpf_linker__new;
> bpf_map__inner_map;
> + bpf_map__get_initial_value;
nit: g < i, and as bpf_map__initial_value will still go before inner_map getter
> bpf_object__gen_loader;
> bpf_object__set_kversion;
> } LIBBPF_0.3.0;
> --
> 2.30.2
>
