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authorKevin Paul Herbert <kph@cisco.com>2015-12-08 19:53:45 -0800
committerGerrit Code Review <gerrit@fd.io>2016-01-27 18:58:26 +0000
commitcf121e3d5135c1c06ccca35372126baf5559e144 (patch)
tree1f389dae64a22a920e81852901c945cbc2a887f3
parentc42508d1581fc1ad4afe2e234fb1f1f005613eb5 (diff)
ip_checksum.c: Fixes for ip_csum_and_memcpy() alignment issues
Add explicit support for incremental operations which may be on byte boundaries and misaligned. Since this is a memcpy() like function, it needs to be robust in all byte operations. Add code to perform the checksum 16 bits at a time when the destination buffer pointer is not naturally aligned. The previous code did support misaligned source data (via clib_mem_unaligned()), but didn't properly align the destination pointer. It would be possible to further optimize this by adding an optimzed move operation where the source is aligned on natural boundaries. Look at this as we optimize this function. At this point, I am concentrating on correctness. Change-Id: I2b0fd4795ec5c0ca294a733159c7355b54177690 Signed-off-by: Kevin Paul Herbert <kph@cisco.com>
-rw-r--r--vnet/vnet/ip/ip_checksum.c104
-rw-r--r--vnet/vnet/ip/ip_packet.h18
2 files changed, 69 insertions, 53 deletions
diff --git a/vnet/vnet/ip/ip_checksum.c b/vnet/vnet/ip/ip_checksum.c
index 23e7889bc7e..680b7a44c63 100644
--- a/vnet/vnet/ip/ip_checksum.c
+++ b/vnet/vnet/ip/ip_checksum.c
@@ -109,76 +109,110 @@ do { \
ip_csum_t
ip_csum_and_memcpy (ip_csum_t sum, void * dst, void * src, uword n_bytes)
{
- uword n_left, n_left_odd;
- ip_csum_t * dst_even, * src_even;
+ uword n_left;
ip_csum_t sum0 = sum, sum1;
-
- dst_even = uword_to_pointer
- (pointer_to_uword (dst) &~ (sizeof (sum) - 1),
- ip_csum_t *);
- src_even = src;
-
n_left = n_bytes;
- if ((n_left_odd = dst - (void *) dst_even))
- {
- u8 * d8 = dst, * s8 = src;
- uword i, n_copy_odd;
- n_copy_odd = clib_min (n_left, n_left_odd);
+ if (n_left && (pointer_to_uword (dst) & sizeof(u8)))
+ {
+ u8 * d8, val;
+
+ d8 = dst;
+ val = ((u8 *)src)[0];
+ d8[0] = val;
+ dst += 1;
+ src += 1;
+ n_left -= 1;
+ sum0 = ip_csum_with_carry (sum0, val << (8 * CLIB_ARCH_IS_LITTLE_ENDIAN));
+ }
- for (i = 0; i < n_copy_odd; i++)
- d8[i] = s8[i];
+ while ((n_left >= sizeof (u16)) && (pointer_to_uword (dst) & (sizeof (sum) - sizeof (u16))))
+ {
+ u16 * d16, * s16;
- if (n_copy_odd != n_left_odd)
- return sum0;
+ d16 = dst;
+ s16 = src;
+
+ d16[0] = clib_mem_unaligned (&s16[0], u16);
- sum0 = ip_csum_with_carry (sum0, dst_even[0]);
- dst_even += 1;
- src_even = (void *) (src + n_copy_odd);
- n_left -= n_left_odd;
+ sum0 = ip_csum_with_carry (sum0, d16[0]);
+ dst += sizeof (u16);
+ src += sizeof (u16);
+ n_left -= sizeof (u16);
}
sum1 = 0;
- while (n_left >= 2 * sizeof (dst_even[0]))
+ while (n_left >= 2 * sizeof (sum))
{
ip_csum_t dst0, dst1;
+ ip_csum_t *dst_even, *src_even;
+ dst_even = dst;
+ src_even = src;
dst0 = clib_mem_unaligned (&src_even[0], ip_csum_t);
dst1 = clib_mem_unaligned (&src_even[1], ip_csum_t);
dst_even[0] = dst0;
dst_even[1] = dst1;
- dst_even += 2;
- src_even += 2;
+ dst += 2 * sizeof(dst_even[0]);
+ src += 2 * sizeof(dst_even[0]);
n_left -= 2 * sizeof (dst_even[0]);
sum0 = ip_csum_with_carry (sum0, dst0);
sum1 = ip_csum_with_carry (sum1, dst1);
}
- if (n_left >= 1 * sizeof (dst_even[0]))
+ sum0 = ip_csum_with_carry (sum0, sum1);
+ while (n_left >= 1 * sizeof (sum))
{
- ip_csum_t dst0;
+ ip_csum_t dst0, *dst_even, *src_even;
+
+ dst_even = dst;
+ src_even = src;
dst0 = clib_mem_unaligned (&src_even[0], ip_csum_t);
dst_even[0] = dst0;
- dst_even += 1;
- src_even += 1;
- n_left -= 1 * sizeof (dst_even[0]);
+ dst += 1 * sizeof(sum);
+ src += 1 * sizeof(sum);
+ n_left -= 1 * sizeof (sum);
sum0 = ip_csum_with_carry (sum0, dst0);
}
- if (n_left > 0)
+ while (n_left >= sizeof (u16))
{
- u8 * d8 = dst, * s8 = src;
- uword i;
- for (i = 0; i < n_left; i++)
- d8[i] = s8[i];
+ u16 dst0, *dst_short, *src_short;
+
+ dst_short = dst;
+ src_short = src;
+
+ dst0 = clib_mem_unaligned (&src_short[0], u16);
+
+ dst_short[0] = dst0;
+
+ sum0 = ip_csum_with_carry (sum0, dst_short[0]);
+ dst += 1 * sizeof (dst0);
+ src += 1 * sizeof (dst0);
+ n_left -= 1 * sizeof (dst0);
+
+ }
+
+ if (n_left == 1)
+ {
+ u8 * d8, * s8, val;
+
+ d8 = dst;
+ s8 = src;
+
+ d8[0] = val = s8[0];
+ d8 += 1;
+ s8 += 1;
+ n_left -= 1;
+ sum0 = ip_csum_with_carry (sum0, val << (8 * CLIB_ARCH_IS_BIG_ENDIAN));
}
- return ip_csum_with_carry (sum0, sum1);
+ return sum0;
}
diff --git a/vnet/vnet/ip/ip_packet.h b/vnet/vnet/ip/ip_packet.h
index fb9a23604e1..6fcd0071ef1 100644
--- a/vnet/vnet/ip/ip_packet.h
+++ b/vnet/vnet/ip/ip_packet.h
@@ -156,24 +156,6 @@ ip_csum_t ip_csum_and_memcpy (ip_csum_t sum, void * dst, void * src, uword n_byt
always_inline u16
ip_csum_and_memcpy_fold (ip_csum_t sum, void * dst)
{
- uword n_zero;
- ip_csum_t * dst_even;
-
- dst_even = uword_to_pointer
- (pointer_to_uword (dst) &~ (sizeof (sum) - 1),
- ip_csum_t *);
-
- if ((n_zero = dst - (void *) dst_even))
- {
- u8 * d8 = dst;
- uword i;
-
- for (i = 0; i < n_zero; i++)
- d8[i] = 0;
-
- sum = ip_csum_with_carry (sum, dst_even[0]);
- }
-
return ip_csum_fold (sum);
}