1 files changed, 53 insertions, 0 deletions
diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c
index cfa1c18e3a48..9876c5fe6c2a 100644
--- a/kernel/bpf/cpumask.c
+++ b/kernel/bpf/cpumask.c
@@ -45,6 +45,10 @@ __bpf_kfunc_start_defs();
  *
  * bpf_cpumask_create() allocates memory using the BPF memory allocator, and
  * will not block. It may return NULL if no memory is available.
+ *
+ * Return:
+ * * A pointer to a new struct bpf_cpumask instance on success.
+ * * NULL if the BPF memory allocator is out of memory.
  */
 __bpf_kfunc struct bpf_cpumask *bpf_cpumask_create(void)
 {
@@ -71,6 +75,10 @@ __bpf_kfunc struct bpf_cpumask *bpf_cpumask_create(void)
  * Acquires a reference to a BPF cpumask. The cpumask returned by this function
  * must either be embedded in a map as a kptr, or freed with
  * bpf_cpumask_release().
+ *
+ * Return:
+ * * The struct bpf_cpumask pointer passed to the function.
+ *
  */
 __bpf_kfunc struct bpf_cpumask *bpf_cpumask_acquire(struct bpf_cpumask *cpumask)
 {
@@ -106,6 +114,9 @@ CFI_NOSEAL(bpf_cpumask_release_dtor);
  *
  * Find the index of the first nonzero bit of the cpumask. A struct bpf_cpumask
  * pointer may be safely passed to this function.
+ *
+ * Return:
+ * * The index of the first nonzero bit in the struct cpumask.
  */
 __bpf_kfunc u32 bpf_cpumask_first(const struct cpumask *cpumask)
 {
@@ -119,6 +130,9 @@ __bpf_kfunc u32 bpf_cpumask_first(const struct cpumask *cpumask)
  *
  * Find the index of the first unset bit of the cpumask. A struct bpf_cpumask
  * pointer may be safely passed to this function.
+ *
+ * Return:
+ * * The index of the first zero bit in the struct cpumask.
  */
 __bpf_kfunc u32 bpf_cpumask_first_zero(const struct cpumask *cpumask)
 {
@@ -133,6 +147,9 @@ __bpf_kfunc u32 bpf_cpumask_first_zero(const struct cpumask *cpumask)
  *
  * Find the index of the first nonzero bit of the AND of two cpumasks.
  * struct bpf_cpumask pointers may be safely passed to @src1 and @src2.
+ *
+ * Return:
+ * * The index of the first bit that is nonzero in both cpumask instances.
  */
 __bpf_kfunc u32 bpf_cpumask_first_and(const struct cpumask *src1,
 				      const struct cpumask *src2)
@@ -414,12 +431,47 @@ __bpf_kfunc u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1,
  * @cpumask: The cpumask being queried.
  *
  * Count the number of set bits in the given cpumask.
+ *
+ * Return:
+ * * The number of bits set in the mask.
  */
 __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 +500,7 @@ 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 = {