| Message ID | 20200328182834.196578-1-toke@redhat.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [v3,1/2] libbpf: Add setter for initial value for internal maps | expand |
On Sat, Mar 28, 2020 at 11:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote: > > For internal maps (most notably the maps backing global variables), libbpf > uses an internal mmaped area to store the data after opening the object. > This data is subsequently copied into the kernel map when the object is > loaded. > > This adds a function to set a new value for that data, which can be used to > before it is loaded into the kernel. This is especially relevant for RODATA > maps, since those are frozen on load. > > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> > --- > v3: > - Add a setter for the initial value instead of a getter for the pointer to it > - Add selftest > v2: > - Add per-map getter for data area instead of a global rodata getter for bpf_obj > > tools/lib/bpf/libbpf.c | 11 +++++++++++ > tools/lib/bpf/libbpf.h | 2 ++ > tools/lib/bpf/libbpf.map | 1 + > 3 files changed, 14 insertions(+) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 085e41f9b68e..f9953a8ffcfa 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -6756,6 +6756,17 @@ void *bpf_map__priv(const struct bpf_map *map) > return map ? map->priv : ERR_PTR(-EINVAL); > } > > +int bpf_map__set_initial_value(struct bpf_map *map, > + void *data, size_t size) nit: const void * > +{ > + if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG || > + size != map->def.value_size) > + return -EINVAL; > + How about also checking that bpf_map wasn't yet created? Checking map->fd >= 0 should be enough. > + memcpy(map->mmaped, data, size); > + 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 d38d7a629417..ee30ed487221 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -407,6 +407,8 @@ typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *); > LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv, > bpf_map_clear_priv_t clear_priv); > LIBBPF_API void *bpf_map__priv(const struct bpf_map *map); > +LIBBPF_API int bpf_map__set_initial_value(struct bpf_map *map, > + void *data, size_t size); > LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd); > LIBBPF_API int bpf_map__resize(struct bpf_map *map, __u32 max_entries); > LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map); > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map > index 5129283c0284..f46873b9fe5e 100644 > --- a/tools/lib/bpf/libbpf.map > +++ b/tools/lib/bpf/libbpf.map > @@ -243,5 +243,6 @@ LIBBPF_0.0.8 { > bpf_link__pin; > bpf_link__pin_path; > bpf_link__unpin; > + bpf_map__set_initial_value; > bpf_program__set_attach_target; > } LIBBPF_0.0.7; > -- > 2.26.0 >
Andrii Nakryiko <andrii.nakryiko@gmail.com> writes: > On Sat, Mar 28, 2020 at 11:29 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote: >> >> For internal maps (most notably the maps backing global variables), libbpf >> uses an internal mmaped area to store the data after opening the object. >> This data is subsequently copied into the kernel map when the object is >> loaded. >> >> This adds a function to set a new value for that data, which can be used to >> before it is loaded into the kernel. This is especially relevant for RODATA >> maps, since those are frozen on load. >> >> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> >> --- >> v3: >> - Add a setter for the initial value instead of a getter for the pointer to it >> - Add selftest >> v2: >> - Add per-map getter for data area instead of a global rodata getter for bpf_obj >> >> tools/lib/bpf/libbpf.c | 11 +++++++++++ >> tools/lib/bpf/libbpf.h | 2 ++ >> tools/lib/bpf/libbpf.map | 1 + >> 3 files changed, 14 insertions(+) >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index 085e41f9b68e..f9953a8ffcfa 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -6756,6 +6756,17 @@ void *bpf_map__priv(const struct bpf_map *map) >> return map ? map->priv : ERR_PTR(-EINVAL); >> } >> >> +int bpf_map__set_initial_value(struct bpf_map *map, >> + void *data, size_t size) > > nit: const void * ACK. >> +{ >> + if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG || >> + size != map->def.value_size) >> + return -EINVAL; >> + > > How about also checking that bpf_map wasn't yet created? Checking > map->fd >= 0 should be enough. Yup, makes sense. >> + memcpy(map->mmaped, data, size); >> + 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 d38d7a629417..ee30ed487221 100644 >> --- a/tools/lib/bpf/libbpf.h >> +++ b/tools/lib/bpf/libbpf.h >> @@ -407,6 +407,8 @@ typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *); >> LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv, >> bpf_map_clear_priv_t clear_priv); >> LIBBPF_API void *bpf_map__priv(const struct bpf_map *map); >> +LIBBPF_API int bpf_map__set_initial_value(struct bpf_map *map, >> + void *data, size_t size); >> LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd); >> LIBBPF_API int bpf_map__resize(struct bpf_map *map, __u32 max_entries); >> LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map); >> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map >> index 5129283c0284..f46873b9fe5e 100644 >> --- a/tools/lib/bpf/libbpf.map >> +++ b/tools/lib/bpf/libbpf.map >> @@ -243,5 +243,6 @@ LIBBPF_0.0.8 { >> bpf_link__pin; >> bpf_link__pin_path; >> bpf_link__unpin; >> + bpf_map__set_initial_value; >> bpf_program__set_attach_target; >> } LIBBPF_0.0.7; >> -- >> 2.26.0 >>
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 085e41f9b68e..f9953a8ffcfa 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -6756,6 +6756,17 @@ void *bpf_map__priv(const struct bpf_map *map) return map ? map->priv : ERR_PTR(-EINVAL); } +int bpf_map__set_initial_value(struct bpf_map *map, + void *data, size_t size) +{ + if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG || + size != map->def.value_size) + return -EINVAL; + + memcpy(map->mmaped, data, size); + 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 d38d7a629417..ee30ed487221 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -407,6 +407,8 @@ typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *); LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv, bpf_map_clear_priv_t clear_priv); LIBBPF_API void *bpf_map__priv(const struct bpf_map *map); +LIBBPF_API int bpf_map__set_initial_value(struct bpf_map *map, + void *data, size_t size); LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd); LIBBPF_API int bpf_map__resize(struct bpf_map *map, __u32 max_entries); LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map); diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 5129283c0284..f46873b9fe5e 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -243,5 +243,6 @@ LIBBPF_0.0.8 { bpf_link__pin; bpf_link__pin_path; bpf_link__unpin; + bpf_map__set_initial_value; bpf_program__set_attach_target; } LIBBPF_0.0.7;
For internal maps (most notably the maps backing global variables), libbpf uses an internal mmaped area to store the data after opening the object. This data is subsequently copied into the kernel map when the object is loaded. This adds a function to set a new value for that data, which can be used to before it is loaded into the kernel. This is especially relevant for RODATA maps, since those are frozen on load. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> --- v3: - Add a setter for the initial value instead of a getter for the pointer to it - Add selftest v2: - Add per-map getter for data area instead of a global rodata getter for bpf_obj tools/lib/bpf/libbpf.c | 11 +++++++++++ tools/lib/bpf/libbpf.h | 2 ++ tools/lib/bpf/libbpf.map | 1 + 3 files changed, 14 insertions(+)