Hi,
On 2/28/2025 8:33 AM, Emil Tsalapatis wrote:
> Add a helper kfunc that sets the bitmap of a bpf_cpumask from BPF
> memory.
>
> Signed-off-by: Emil Tsalapatis (Meta) <emil@xxxxxxxxxxxxxxx>
> ---
> kernel/bpf/cpumask.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c
> index cfa1c18e3a48..a13839b3595f 100644
> --- a/kernel/bpf/cpumask.c
> +++ b/kernel/bpf/cpumask.c
> @@ -420,6 +420,26 @@ __bpf_kfunc u32 bpf_cpumask_weight(const struct cpumask *cpumask)
> return cpumask_weight(cpumask);
> }
>
> +/**
> + * bpf_cpumask_fill() - Populate the CPU mask from the contents of
> + * a BPF memory region.
> + *
> + * @cpumask: The cpumask being populated.
> + * @src: The BPF memory holding the bit pattern.
> + * @src__sz: Length of the BPF memory region in bytes.
> + *
> + */
> +__bpf_kfunc int bpf_cpumask_fill(struct cpumask *cpumask, void *src, size_t src__sz)
> +{
> + /* The memory region must be large enough to populate the entire CPU mask. */
> + if (src__sz < BITS_TO_BYTES(nr_cpu_ids))
> + return -EACCES;
> +
> + bitmap_copy(cpumask_bits(cpumask), src, nr_cpu_ids);
Should we use src__sz < bitmap_size(nr_cpu_ids) instead ? Because in
bitmap_copy(), it assumes the size of src should be bitmap_size(nr_cpu_ids).
> +
> + return 0;
> +}
> +
> __bpf_kfunc_end_defs();
>
> BTF_KFUNCS_START(cpumask_kfunc_btf_ids)
> @@ -448,6 +468,7 @@ BTF_ID_FLAGS(func, bpf_cpumask_copy, KF_RCU)
> BTF_ID_FLAGS(func, bpf_cpumask_any_distribute, KF_RCU)
> BTF_ID_FLAGS(func, bpf_cpumask_any_and_distribute, KF_RCU)
> BTF_ID_FLAGS(func, bpf_cpumask_weight, KF_RCU)
> +BTF_ID_FLAGS(func, bpf_cpumask_fill, KF_RCU)
> BTF_KFUNCS_END(cpumask_kfunc_btf_ids)
>
> static const struct btf_kfunc_id_set cpumask_kfunc_set = {
