[src/trunk]: src/sys/net if_gre: Remove alignment checks in favour copying to...

[roy <roy%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/77b5c2db7e8d
branches:  trunk
changeset: 959452:77b5c2db7e8d
user:      roy <roy%NetBSD.org@localhost>
date:      Sun Feb 14 19:33:29 2021 +0000

description:
if_gre: Remove alignment checks in favour copying to stack

Makes the code a lot simpler, idea from dyoung@

diffstat:

 sys/net/if_gre.c |  34 +++++++++++++---------------------
 sys/net/if_gre.h |  11 +----------
 2 files changed, 14 insertions(+), 31 deletions(-)

diffs (120 lines):

diff -r 9e39fc1e6fe0 -r 77b5c2db7e8d sys/net/if_gre.c
--- a/sys/net/if_gre.c  Sun Feb 14 18:59:36 2021 +0000
+++ b/sys/net/if_gre.c  Sun Feb 14 19:33:29 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_gre.c,v 1.179 2021/02/13 13:00:16 roy Exp $ */
+/*     $NetBSD: if_gre.c,v 1.180 2021/02/14 19:33:29 roy Exp $ */
 
 /*
  * Copyright (c) 1998, 2008 The NetBSD Foundation, Inc.
@@ -45,7 +45,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_gre.c,v 1.179 2021/02/13 13:00:16 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_gre.c,v 1.180 2021/02/14 19:33:29 roy Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_atalk.h"
@@ -142,6 +142,8 @@
 #define        GRE_DPRINTF(__sc, __fmt, ...)   do { } while (/*CONSTCOND*/0)
 #endif /* GRE_DEBUG */
 
+CTASSERT(sizeof(struct gre_h) == 4);
+
 int ip_gre_ttl = GRE_TTL;
 
 static u_int gre_count;
@@ -374,7 +376,7 @@
 {
        struct gre_softc *sc = (struct gre_softc *)arg;
        int rc;
-       const struct gre_h *gh;
+       struct gre_h gh;
        struct mbuf *m;
 
        GRE_DPRINTF(sc, "enter\n");
@@ -396,24 +398,16 @@
                return;
        }
 
-       /* Enforce alignment */
-       if (GRE_HDR_ALIGNED_P(mtod(m, void *)) == 0) {
-               if ((m = m_copyup(m, sizeof(struct gre_h), 0)) == NULL) {
-                       /* XXXJRT new stat, please */
-                       GRE_DPRINTF(sc, "m_copyup failed\n");
-                       sc->sc_pullup_ev.ev_count++;
-                       return;
-               }
-       } else if (__predict_false(m->m_len < sizeof(struct gre_h))) {
-               if ((m = m_pullup(m, sizeof(struct gre_h))) == NULL) {
+       if (__predict_false(m->m_len < sizeof(gh))) {
+               if ((m = m_pullup(m, sizeof(gh))) == NULL) {
                        GRE_DPRINTF(sc, "m_pullup failed\n");
                        sc->sc_pullup_ev.ev_count++;
                        return;
                }
        }
-       gh = mtod(m, const struct gre_h *);
+       memcpy(&gh, mtod(m, void *), sizeof(gh));
 
-       if (gre_input(sc, m, gh) == 0) {
+       if (gre_input(sc, m, &gh) == 0) {
                sc->sc_unsupp_ev.ev_count++;
                GRE_DPRINTF(sc, "dropping unsupported\n");
                m_freem(m);
@@ -898,7 +892,7 @@
 {
        int error = 0;
        struct gre_softc *sc = ifp->if_softc;
-       struct gre_h *gh;
+       struct gre_h gh = { .flags = 0 };
        uint16_t etype = 0;
 
        KASSERT((m->m_flags & M_PKTHDR) != 0);
@@ -950,17 +944,15 @@
        }
 #endif
 
-       M_PREPEND(m, sizeof(*gh), M_DONTWAIT);
+       M_PREPEND(m, sizeof(gh), M_DONTWAIT);
        if (m == NULL) {
                IF_DROP(&ifp->if_snd);
                error = ENOBUFS;
                goto end;
        }
 
-       gh = mtod(m, struct gre_h *);
-       KASSERT(GRE_HDR_ALIGNED_P(gh));
-       gh->flags = 0;
-       gh->ptype = etype;
+       gh.ptype = etype;
+       memcpy(mtod(m, void *), &gh, sizeof(gh));
        /* XXX Need to handle IP ToS.  Look at how I handle IP TTL. */
 
        if_statadd2(ifp, if_opackets, 1, if_obytes, m->m_pkthdr.len);
diff -r 9e39fc1e6fe0 -r 77b5c2db7e8d sys/net/if_gre.h
--- a/sys/net/if_gre.h  Sun Feb 14 18:59:36 2021 +0000
+++ b/sys/net/if_gre.h  Sun Feb 14 19:33:29 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_gre.h,v 1.48 2021/02/12 19:57:49 roy Exp $ */
+/*     $NetBSD: if_gre.h,v 1.49 2021/02/14 19:33:29 roy Exp $ */
 
 /*
  * Copyright (c) 1998, 2008 The NetBSD Foundation, Inc.
@@ -131,15 +131,6 @@
                                Present if (rt_pres == 1)
  */
 };
-#ifdef __NO_STRICT_ALIGNMENT
-#define        GRE_HDR_ALIGNED_P(gh)   1
-#else
-#define        GRE_HDR_ALIGNED_P(gh)   ((((vaddr_t) (gh)) & 3) == 0)
-#endif
-#ifdef __CTASSERT
-__CTASSERT(sizeof(struct gre_h) == 4);
-#endif
-
 #define GRE_CP         0x8000  /* Checksum Present */
 #define GRE_RP         0x4000  /* Routing Present */
 #define GRE_KP         0x2000  /* Key Present */