Commit 950ad93d authored by Emil Tsalapatis's avatar Emil Tsalapatis Committed by Alexei Starovoitov
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bpf: add kfunc for populating cpumask bits 



Add a helper kfunc that sets the bitmap of a bpf_cpumask from BPF memory.

Signed-off-by: default avatarEmil Tsalapatis (Meta) <emil@etsalapatis.com>
Acked-by: default avatarHou Tao <houtao1@huawei.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250309230427.26603-2-emil@etsalapatis.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 103b9ab9

kernel/bpf/cpumask.c

+33 −0
Original line number Diff line number Diff line
@@ -420,6 +420,38 @@ __bpf_kfunc u32 bpf_cpumask_weight(const struct cpumask *cpumask) 
	return cpumask_weight(cpumask);

}



/**

 * bpf_cpumask_populate() - 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.

 *

 * Return:

 * * 0 if the struct cpumask * instance was populated successfully.

 * * -EACCES if the memory region is too small to populate the cpumask.

 * * -EINVAL if the memory region is not aligned to the size of a long

 *   and the architecture does not support efficient unaligned accesses.

 */

__bpf_kfunc int bpf_cpumask_populate(struct cpumask *cpumask, void *src, size_t src__sz)

{

	unsigned long source = (unsigned long)src;



	/* The memory region must be large enough to populate the entire CPU mask. */

	if (src__sz < bitmap_size(nr_cpu_ids))

		return -EACCES;



	/* If avoiding unaligned accesses, the input region must be aligned to the nearest long. */

	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) &&

		!IS_ALIGNED(source, sizeof(long)))

		return -EINVAL;



	bitmap_copy(cpumask_bits(cpumask), src, nr_cpu_ids);



	return 0;

}



__bpf_kfunc_end_defs();



BTF_KFUNCS_START(cpumask_kfunc_btf_ids)
@@ -448,6 +480,7 @@ 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_populate, KF_RCU)

BTF_KFUNCS_END(cpumask_kfunc_btf_ids)



static const struct btf_kfunc_id_set cpumask_kfunc_set = {