On Wed, Aug 27, 2025 at 9:45 AM Leon Hwang <leon.hwang@xxxxxxxxx> wrote:
>
> It is to unify map flags checking for lookup_elem, update_elem,
> lookup_batch and update_batch APIs.
>
> Therefore, it will be convenient to check BPF_F_CPU and BPF_F_ALL_CPUS
> flags in it for these APIs in next patch.
>
> Signed-off-by: Leon Hwang <leon.hwang@xxxxxxxxx>
> ---
> include/linux/bpf.h | 28 ++++++++++++++++++++++++++++
> kernel/bpf/syscall.c | 34 +++++++++++-----------------------
> 2 files changed, 39 insertions(+), 23 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 8f6e87f0f3a89..512717d442c09 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -3709,4 +3709,32 @@ int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char *
> const char **linep, int *nump);
> struct bpf_prog *bpf_prog_find_from_stack(void);
>
> +static inline int bpf_map_check_op_flags(struct bpf_map *map, u64 flags, u64 extra_flags_mask)
> +{
> + if (extra_flags_mask && (flags & extra_flags_mask))
doh, Leon... when extra_flags_mask == 0, `flags & extra_flags_mask` is
always false, so just:
if (flags & extra_flags_mask)
return -EINVAL;
But it feels more natural to reverse the meaning of this and treat it
as extra *allowed flags*. So zero would mean no extra flags should be
there (most strict case) and ~0 would mean "we don't care or will
check later". And so in the code you'd have
if (flags & ~extra_flags) /* check for any unsupported flags */
return -EINVAL;
But I need someone else to do a reality check on me here at this point.
> + return -EINVAL;
> +
> + if ((flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static inline int bpf_map_check_update_flags(struct bpf_map *map, u64 flags)
> +{
> + return bpf_map_check_op_flags(map, flags, 0);
> +}
> +
> +#define BPF_MAP_LOOKUP_ELEM_EXTRA_FLAGS_MASK (~BPF_F_LOCK)
> +
> +static inline int bpf_map_check_lookup_flags(struct bpf_map *map, u64 flags)
> +{
> + return bpf_map_check_op_flags(map, flags, BPF_MAP_LOOKUP_ELEM_EXTRA_FLAGS_MASK);
> +}
> +
> +static inline int bpf_map_check_batch_flags(struct bpf_map *map, u64 flags)
> +{
> + return bpf_map_check_op_flags(map, flags, BPF_MAP_LOOKUP_ELEM_EXTRA_FLAGS_MASK);
> +}
> +
> #endif /* _LINUX_BPF_H */
[...]
