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bpf: add kfunc for populating cpumask bits

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

Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250309230427.26603-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Emil Tsalapatis 2025-03-09 19:04:24 -04:00 committed by Alexei Starovoitov
parent 103b9ab96a
commit 950ad93df2
1 changed files with 33 additions and 0 deletions
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33
kernel/bpf/cpumask.c
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@ -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 = {