SELinux: improve performance when AVC misses.
* We add ebitmap_for_each_positive_bit() which enables to walk on
any positive bit on the given ebitmap, to improve its performance
using common bit-operations defined in linux/bitops.h.
In the previous version, this logic was implemented using a combination
of ebitmap_for_each_bit() and ebitmap_node_get_bit(), but is was worse
in performance aspect.
This logic is most frequestly used to compute a new AVC entry,
so this patch can improve SELinux performance when AVC misses are happen.
* struct ebitmap_node is redefined as an array of "unsigned long", to get
suitable for using find_next_bit() which is fasted than iteration of
shift and logical operation, and to maximize memory usage allocated
from general purpose slab.
* Any ebitmap_for_each_bit() are repleced by the new implementation
in ss/service.c and ss/mls.c. Some of related implementation are
changed, however, there is no incompatibility with the previous
version.
* The width of any new line are less or equal than 80-chars.
The following benchmark shows the effect of this patch, when we
access many files which have different security context one after
another. The number is more than /selinux/avc/cache_threshold, so
any access always causes AVC misses.
selinux-2.6 selinux-2.6-ebitmap
AVG: 22.763 [s] 8.750 [s]
STD: 0.265 0.019
------------------------------------------
1st: 22.558 [s] 8.786 [s]
2nd: 22.458 [s] 8.750 [s]
3rd: 22.478 [s] 8.754 [s]
4th: 22.724 [s] 8.745 [s]
5th: 22.918 [s] 8.748 [s]
6th: 22.905 [s] 8.764 [s]
7th: 23.238 [s] 8.726 [s]
8th: 22.822 [s] 8.729 [s]
Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h
index 1270e34..e38a327 100644
--- a/security/selinux/ss/ebitmap.h
+++ b/security/selinux/ss/ebitmap.h
@@ -16,14 +16,16 @@
#include <net/netlabel.h>
-#define MAPTYPE u64 /* portion of bitmap in each node */
-#define MAPSIZE (sizeof(MAPTYPE) * 8) /* number of bits in node bitmap */
-#define MAPBIT 1ULL /* a bit in the node bitmap */
+#define EBITMAP_UNIT_NUMS ((32 - sizeof(void *) - sizeof(u32)) \
+ / sizeof(unsigned long))
+#define EBITMAP_UNIT_SIZE BITS_PER_LONG
+#define EBITMAP_SIZE (EBITMAP_UNIT_NUMS * EBITMAP_UNIT_SIZE)
+#define EBITMAP_BIT 1ULL
struct ebitmap_node {
- u32 startbit; /* starting position in the total bitmap */
- MAPTYPE map; /* this node's portion of the bitmap */
struct ebitmap_node *next;
+ unsigned long maps[EBITMAP_UNIT_NUMS];
+ u32 startbit;
};
struct ebitmap {
@@ -34,11 +36,17 @@
#define ebitmap_length(e) ((e)->highbit)
#define ebitmap_startbit(e) ((e)->node ? (e)->node->startbit : 0)
-static inline unsigned int ebitmap_start(struct ebitmap *e,
- struct ebitmap_node **n)
+static inline unsigned int ebitmap_start_positive(struct ebitmap *e,
+ struct ebitmap_node **n)
{
- *n = e->node;
- return ebitmap_startbit(e);
+ unsigned int ofs;
+
+ for (*n = e->node; *n; *n = (*n)->next) {
+ ofs = find_first_bit((*n)->maps, EBITMAP_SIZE);
+ if (ofs < EBITMAP_SIZE)
+ return (*n)->startbit + ofs;
+ }
+ return ebitmap_length(e);
}
static inline void ebitmap_init(struct ebitmap *e)
@@ -46,28 +54,65 @@
memset(e, 0, sizeof(*e));
}
-static inline unsigned int ebitmap_next(struct ebitmap_node **n,
- unsigned int bit)
+static inline unsigned int ebitmap_next_positive(struct ebitmap *e,
+ struct ebitmap_node **n,
+ unsigned int bit)
{
- if ((bit == ((*n)->startbit + MAPSIZE - 1)) &&
- (*n)->next) {
- *n = (*n)->next;
- return (*n)->startbit;
- }
+ unsigned int ofs;
- return (bit+1);
+ ofs = find_next_bit((*n)->maps, EBITMAP_SIZE, bit - (*n)->startbit + 1);
+ if (ofs < EBITMAP_SIZE)
+ return ofs + (*n)->startbit;
+
+ for (*n = (*n)->next; *n; *n = (*n)->next) {
+ ofs = find_first_bit((*n)->maps, EBITMAP_SIZE);
+ if (ofs < EBITMAP_SIZE)
+ return ofs + (*n)->startbit;
+ }
+ return ebitmap_length(e);
}
-static inline int ebitmap_node_get_bit(struct ebitmap_node * n,
+#define EBITMAP_NODE_INDEX(node, bit) \
+ (((bit) - (node)->startbit) / EBITMAP_UNIT_SIZE)
+#define EBITMAP_NODE_OFFSET(node, bit) \
+ (((bit) - (node)->startbit) % EBITMAP_UNIT_SIZE)
+
+static inline int ebitmap_node_get_bit(struct ebitmap_node *n,
unsigned int bit)
{
- if (n->map & (MAPBIT << (bit - n->startbit)))
+ unsigned int index = EBITMAP_NODE_INDEX(n, bit);
+ unsigned int ofs = EBITMAP_NODE_OFFSET(n, bit);
+
+ BUG_ON(index >= EBITMAP_UNIT_NUMS);
+ if ((n->maps[index] & (EBITMAP_BIT << ofs)))
return 1;
return 0;
}
-#define ebitmap_for_each_bit(e, n, bit) \
- for (bit = ebitmap_start(e, &n); bit < ebitmap_length(e); bit = ebitmap_next(&n, bit)) \
+static inline void ebitmap_node_set_bit(struct ebitmap_node *n,
+ unsigned int bit)
+{
+ unsigned int index = EBITMAP_NODE_INDEX(n, bit);
+ unsigned int ofs = EBITMAP_NODE_OFFSET(n, bit);
+
+ BUG_ON(index >= EBITMAP_UNIT_NUMS);
+ n->maps[index] |= (EBITMAP_BIT << ofs);
+}
+
+static inline void ebitmap_node_clr_bit(struct ebitmap_node *n,
+ unsigned int bit)
+{
+ unsigned int index = EBITMAP_NODE_INDEX(n, bit);
+ unsigned int ofs = EBITMAP_NODE_OFFSET(n, bit);
+
+ BUG_ON(index >= EBITMAP_UNIT_NUMS);
+ n->maps[index] &= ~(EBITMAP_BIT << ofs);
+}
+
+#define ebitmap_for_each_positive_bit(e, n, bit) \
+ for (bit = ebitmap_start_positive(e, &n); \
+ bit < ebitmap_length(e); \
+ bit = ebitmap_next_positive(e, &n, bit)) \
int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2);
int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src);