In article <5912ca9e-b4e7-423d-a45d-f4693d1c9...@zoulas.com>,
Christos Zoulas wrote:
>-=-=-=-=-=-
Here's the final changes
- Make ALIGNED_POINTER use __alignof(t) instead of sizeof(t). This is more
correct because it works with non-primitive types and provides the ABI
alignment for the type the compiler will use.
- Remove all the *_HDR_ALIGNMENT macros and asserts
- Replace POINTER_ALIGNED_P with ACCESSIBLE_POINTER which is identical to
ALIGNED_POINTER, but returns that the pointer is always aligned if the
CPU supports unaligned accesses.
Index: sys/mbuf.h
===
RCS file: /cvsroot/src/sys/sys/mbuf.h,v
retrieving revision 1.231
diff -u -u -r1.231 mbuf.h
--- sys/mbuf.h 17 Feb 2021 22:32:04 - 1.231
+++ sys/mbuf.h 17 Feb 2021 23:54:31 -
@@ -843,15 +843,21 @@
m->m_pkthdr.rcvif_index = n->m_pkthdr.rcvif_index;
}
+#define M_GET_ALIGNED_HDR(m, type, linkhdr) \
+m_get_aligned_hdr((m), __alignof(type) - 1, sizeof(type), (linkhdr))
+
static __inline int
-m_get_aligned_hdr(struct mbuf **m, int align, size_t hlen, bool linkhdr)
+m_get_aligned_hdr(struct mbuf **m, int mask, size_t hlen, bool linkhdr)
{
- if (POINTER_ALIGNED_P(mtod(*m, void *), align) == 0) {
- --align;// Turn into mask
+#ifndef __NO_STRICT_ALIGNMENT
+ if (((uintptr_t)mtod(*m, void *) & mask) != 0)
*m = m_copyup(*m, hlen,
- linkhdr ? (max_linkhdr + align) & ~align : 0);
- } else if (__predict_false((size_t)(*m)->m_len < hlen))
+ linkhdr ? (max_linkhdr + mask) & ~mask : 0);
+ else
+#endif
+ if (__predict_false((size_t)(*m)->m_len < hlen))
*m = m_pullup(*m, hlen);
+
return *m == NULL;
}
Index: sys/param.h
===
RCS file: /cvsroot/src/sys/sys/param.h,v
retrieving revision 1.689
diff -u -u -r1.689 param.h
--- sys/param.h 17 Feb 2021 22:32:04 - 1.689
+++ sys/param.h 17 Feb 2021 23:54:31 -
@@ -281,16 +281,24 @@
#defineALIGN(p)(((uintptr_t)(p) + ALIGNBYTES) &
~ALIGNBYTES)
#endif
#ifndef ALIGNED_POINTER
-#defineALIGNED_POINTER(p,t)uintptr_t)(p)) & (sizeof(t) - 1))
== 0)
+#defineALIGNED_POINTER(p,t)uintptr_t)(p)) & (__alignof(t) -
1)) == 0)
#endif
#ifndef ALIGNED_POINTER_LOAD
#defineALIGNED_POINTER_LOAD(q,p,t) (*(q) = *((const t *)(p)))
#endif
+/*
+ * Return if the pointer p is accessible for type t. For primitive types
+ * this means that the pointer itself can be dereferenced; for structures
+ * and unions this means that any field can be dereferenced. On CPUs
+ * that allow unaligned pointer access, we always return that the pointer
+ * is accessible to prevent unnecessary copies, although this might not be
+ * necessarily faster.
+ */
#ifdef __NO_STRICT_ALIGNMENT
-#definePOINTER_ALIGNED_P(p, a) 1
+#defineACCESSIBLE_POINTER(p, t)1
#else
-#definePOINTER_ALIGNED_P(p, a) (((uintptr_t)(p) & ((a) - 1))
== 0)
+#defineACCESSIBLE_POINTER(p, t)ALIGNED_POINTER(p, t)
#endif
/*
Index: net/if_arp.h
===
RCS file: /cvsroot/src/sys/net/if_arp.h,v
retrieving revision 1.42
diff -u -u -r1.42 if_arp.h
--- net/if_arp.h17 Feb 2021 22:32:04 - 1.42
+++ net/if_arp.h17 Feb 2021 23:54:31 -
@@ -72,8 +72,6 @@
uint8_t ar_tpa[]; /* target protocol address */
#endif
};
-#defineARP_HDR_ALIGNMENT __alignof(struct arphdr)
-__CTASSERT(ARP_HDR_ALIGNMENT == 2);
static __inline uint8_t *
ar_data(struct arphdr *ap)
Index: net/if_bridge.c
===
RCS file: /cvsroot/src/sys/net/if_bridge.c,v
retrieving revision 1.178
diff -u -u -r1.178 if_bridge.c
--- net/if_bridge.c 14 Feb 2021 20:58:34 - 1.178
+++ net/if_bridge.c 17 Feb 2021 23:54:31 -
@@ -2806,7 +2806,7 @@
if (*mp == NULL)
return -1;
- if (m_get_aligned_hdr(, IP_HDR_ALIGNMENT, sizeof(*ip), true) != 0) {
+ if (M_GET_ALIGNED_HDR(, struct ip, true) != 0) {
/* XXXJRT new stat, please */
ip_statinc(IP_STAT_TOOSMALL);
goto bad;
@@ -2900,7 +2900,7 @@
* it. Otherwise, if it is aligned, make sure the entire base
* IPv6 header is in the first mbuf of the chain.
*/
- if (m_get_aligned_hdr(, IP6_HDR_ALIGNMENT, sizeof(*ip6), true) != 0) {
+ if (M_GET_ALIGNED_HDR(, struct ip6_hdr, true) != 0) {
struct ifnet *inifp = m_get_rcvif_NOMPSAFE(m);
/* XXXJRT new stat, please */
ip6_statinc(IP6_STAT_TOOSMALL);
Index: netinet/if_arp.c
===
RCS file:
