On 11/18/19 7:46 PM, Andrii Nakryiko wrote:
On Mon, Nov 18, 2019 at 10:39 AM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
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.
no one will prevent doing container_of() and get bpf_prog itself, so
it's just an implicit knowledge that bpf_prog might be incomplete yet,
that has to be remembered (btw, might be good to add a brief comment
stating that). But I don't feel strongly either way.
Makes sense, expanded the comment to state this.
Thanks,
Daniel
