Re: [PATCH] Improve SELinux performance when AVC misses.

[KaiGai Kohei <kaigai@kaigai.gr.jp>]

>> --------
>> +#if EBITMAP_UNIT_SIZE == 64
>> +		n->maps[index] = map;
>> +#else
>>   		while (map) {
>>   			n->maps[index] = map & (-1UL);
>>   			map = map >> EBITMAP_UNIT_SIZE;
>>   			index++;
>>   		}
>> +#endif
>> --------

- snip -

>> [kaigai@masu ~]$ ./a.out
>> code       = ffffffffffffffff
>> code >> 16 = 0000ffffffffffff
>> code >> 63 = 0000000000000001
>> code >> 64 = ffffffffffffffff
>> code >> 65 = 7fffffffffffffff
>> [kaigai@masu ~]$ uname -m
>> x86_64
>>
>> I was suprised at. :-)
> 
> Me too.  But see:
> http://gcc.gnu.org/ml/gcc/2004-11/msg01133.html
> http://marc.info/?t=118688311400003&r=1&w=2

#if ... #endif block was removed in the previous patch.
I added a macro that shifts a variable by the width of unsigned long,
defined as follows:

   #define EBITMAP_SHIFT_UNIT_SIZE(x)			\
   	(((x) >> EBITMAP_UNIT_SIZE / 2) >> EBITMAP_UNIT_SIZE / 2)

[PATCH] kills warnings in Improve SELinux performance when AVC misses

This patch kills ugly warnings when the "Improve SELinux performance
when ACV misses" patch.

Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
---
  security/selinux/ss/ebitmap.c |   11 +++++------
  security/selinux/ss/ebitmap.h |    2 ++
  2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index ae44c0c..c1a6b22 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -193,7 +193,7 @@ int ebitmap_netlbl_import(struct ebitmap *ebmap,
  			e_sft = delta % EBITMAP_UNIT_SIZE;
  			while (map) {
  				e_iter->maps[e_idx++] |= map & (-1UL);
-				map >>= EBITMAP_UNIT_SIZE;
+				map = EBITMAP_SHIFT_UNIT_SIZE(map);
  			}
  		}
  		c_iter = c_iter->next;
@@ -389,13 +389,13 @@ int ebitmap_read(struct ebitmap *e, void *fp)

  		if (startbit & (mapunit - 1)) {
  			printk(KERN_ERR "security: ebitmap start bit (%d) is "
-			       "not a multiple of the map unit size (%Zd)\n",
+			       "not a multiple of the map unit size (%u)\n",
  			       startbit, mapunit);
  			goto bad;
  		}
  		if (startbit > e->highbit - mapunit) {
  			printk(KERN_ERR "security: ebitmap start bit (%d) is "
-			       "beyond the end of the bitmap (%Zd)\n",
+			       "beyond the end of the bitmap (%u)\n",
  			       startbit, (e->highbit - mapunit));
  			goto bad;
  		}
@@ -433,9 +433,8 @@ int ebitmap_read(struct ebitmap *e, void *fp)

  		index = (startbit - n->startbit) / EBITMAP_UNIT_SIZE;
  		while (map) {
-			n->maps[index] = map & (-1UL);
-			map = map >> EBITMAP_UNIT_SIZE;
-			index++;
+			n->maps[index++] = map & (-1UL);
+			map = EBITMAP_SHIFT_UNIT_SIZE(map);
  		}
  	}
  ok:
diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h
index e38a327..f283b43 100644
--- a/security/selinux/ss/ebitmap.h
+++ b/security/selinux/ss/ebitmap.h
@@ -21,6 +21,8 @@
  #define EBITMAP_UNIT_SIZE	BITS_PER_LONG
  #define EBITMAP_SIZE		(EBITMAP_UNIT_NUMS * EBITMAP_UNIT_SIZE)
  #define EBITMAP_BIT		1ULL
+#define EBITMAP_SHIFT_UNIT_SIZE(x)					\
+	(((x) >> EBITMAP_UNIT_SIZE / 2) >> EBITMAP_UNIT_SIZE / 2)

  struct ebitmap_node {
  	struct ebitmap_node *next;

--
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