On 11/18/19 6:39 PM, Andrii Nakryiko wrote:
On Thu, Nov 14, 2019 at 5:04 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:This work adds program tracking to prog array maps. This is needed such that upon prog array updates/deletions we can fix up all programs which make use of this tail call map. We add ops->map_poke_{un,}track() helpers to maps to maintain the list of programs and ops->map_poke_run() for triggering the actual update. bpf_array_aux is extended to contain the list head and poke_mutex in order to serialize program patching during updates/deletions. bpf_free_used_maps() will untrack the program shortly before dropping the reference to the map. The prog_array_map_poke_run() is triggered during updates/deletions and walks the maintained prog list. It checks in their poke_tabs whether the map and key is matching and runs the actual bpf_arch_text_poke() for patching in the nop or new jmp location. Depending on the type of update, we use one of BPF_MOD_{NOP_TO_JUMP,JUMP_TO_NOP,JUMP_TO_JUMP}. Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> --- include/linux/bpf.h | 36 +++++++++++++ kernel/bpf/arraymap.c | 120 +++++++++++++++++++++++++++++++++++++++++- kernel/bpf/core.c | 9 +++- 3 files changed, 162 insertions(+), 3 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0ff06a0d0058..62a369fb8d98 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -21,6 +21,7 @@ struct bpf_verifier_env; struct bpf_verifier_log; struct perf_event; struct bpf_prog; +struct bpf_prog_aux; struct bpf_map; struct sock; struct seq_file; @@ -63,6 +64,12 @@ struct bpf_map_ops { const struct btf_type *key_type, const struct btf_type *value_type); + /* Prog poke tracking helpers. */ + int (*map_poke_track)(struct bpf_map *map, struct bpf_prog_aux *aux); + void (*map_poke_untrack)(struct bpf_map *map, struct bpf_prog_aux *aux); + void (*map_poke_run)(struct bpf_map *map, u32 key, struct bpf_prog *old, + struct bpf_prog *new);You are passing bpf_prog_aux for track/untrack, but bpf_prog itself for run. Maybe stick to just bpf_prog everywhere?
This needs to be bpf_prog_aux as prog itself is not stable yet and can still change, but aux itself is stable.
+ /* Direct value access helpers. */ int (*map_direct_value_addr)(const struct bpf_map *map, u64 *imm, u32 off); @@ -584,6 +591,9 @@ struct bpf_array_aux { */ enum bpf_prog_type type; bool jited; + /* Programs with direct jumps into programs part of this array. */ + struct list_head poke_progs; + struct mutex poke_mutex; };[...]
