Iterate on nodes instead of single bits to save node resolution for each
single bit.
Similar to userspace patch efcd00814879 ("libsepol: optimize
ebitmap_and").
Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
---
v3:
apply format style
v2:
fix array size computation
---
security/selinux/ss/ebitmap.c | 50 +++++++++++++++++++++++++++++------
1 file changed, 42 insertions(+), 8 deletions(-)
diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index 67c1a73cd5ee..47cb90106118 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -78,19 +78,53 @@ int ebitmap_cpy(struct ebitmap *dst, const struct ebitmap *src)
int ebitmap_and(struct ebitmap *dst, const struct ebitmap *e1,
const struct ebitmap *e2)
{
- struct ebitmap_node *n;
- int bit, rc;
+ const struct ebitmap_node *n1, *n2;
+ struct ebitmap_node *new = NULL, **prev;
ebitmap_init(dst);
- ebitmap_for_each_positive_bit(e1, n, bit)
- {
- if (ebitmap_get_bit(e2, bit)) {
- rc = ebitmap_set_bit(dst, bit, 1);
- if (rc < 0)
- return rc;
+ prev = &dst->node;
+ n1 = e1->node;
+ n2 = e2->node;
+ while (n1 && n2) {
+ if (n1->startbit == n2->startbit) {
+ unsigned long testmap[EBITMAP_UNIT_NUMS];
+ unsigned int i;
+ bool match = false;
+
+ for (i = 0; i < ARRAY_SIZE(testmap); i++) {
+ testmap[i] = n1->maps[i] & n2->maps[i];
+ if (testmap[i] != 0)
+ match = true;
+ }
+
+ if (match) {
+ new = kmem_cache_zalloc(ebitmap_node_cachep,
+ GFP_ATOMIC);
+ if (!new) {
+ ebitmap_destroy(dst);
+ return -ENOMEM;
+ }
+ new->startbit = n1->startbit;
+ memcpy(new->maps, testmap, EBITMAP_SIZE / 8);
+ new->next = NULL;
+
+ *prev = new;
+ prev = &(new->next);
+ }
+
+ n1 = n1->next;
+ n2 = n2->next;
+ } else if (n1->startbit > n2->startbit) {
+ n2 = n2->next;
+ } else {
+ n1 = n1->next;
}
}
+
+ if (new)
+ dst->highbit = new->startbit + EBITMAP_SIZE;
+
return 0;
}
--
2.43.0
