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bpf: add map_lookup_elem_sys_only for lookups from syscall side
commit c6110222c6
upstream.
Add a callback map_lookup_elem_sys_only() that map implementations
could use over map_lookup_elem() from system call side in case the
map implementation needs to handle the latter differently than from
the BPF data path. If map_lookup_elem_sys_only() is set, this will
be preferred pick for map lookups out of user space. This hook is
used in a follow-up fix for LRU map, but once development window
opens, we can convert other map types from map_lookup_elem() (here,
the one called upon BPF_MAP_LOOKUP_ELEM cmd is meant) over to use
the callback to simplify and clean up the latter.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
ff8af90d56
commit
9f2292309d
2 changed files with 5 additions and 1 deletions
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@ -28,6 +28,7 @@ struct bpf_map_ops {
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void (*map_free)(struct bpf_map *map);
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int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
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void (*map_release_uref)(struct bpf_map *map);
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void *(*map_lookup_elem_sys_only)(struct bpf_map *map, void *key);
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/* funcs callable from userspace and from eBPF programs */
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void *(*map_lookup_elem)(struct bpf_map *map, void *key);
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@ -493,7 +493,10 @@ static int map_lookup_elem(union bpf_attr *attr)
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err = bpf_fd_htab_map_lookup_elem(map, key, value);
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} else {
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rcu_read_lock();
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ptr = map->ops->map_lookup_elem(map, key);
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if (map->ops->map_lookup_elem_sys_only)
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ptr = map->ops->map_lookup_elem_sys_only(map, key);
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else
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ptr = map->ops->map_lookup_elem(map, key);
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if (ptr)
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memcpy(value, ptr, value_size);
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rcu_read_unlock();
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