From: Helge Deller <deller@kernel.org>
To: "David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org
Subject: [PATCH v2] [net] ipv6: Ensure natural alignment of const ipv6 loopback and router addresses
Date: Fri, 26 Jan 2024 09:32:20 +0100 [thread overview]
Message-ID: <ZbNuFM1bFqoH-UoY@p100> (raw)
On a parisc64 kernel I sometimes notice this kernel warning:
Kernel unaligned access to 0x40ff8814 at ndisc_send_skb+0xc0/0x4d8
The address 0x40ff8814 points to the in6addr_linklocal_allrouters
variable and the warning simply means that some ipv6 function tries to
read a 64-bit word directly from the not-64-bit aligned
in6addr_linklocal_allrouters variable.
Unaligned accesses are non-critical as the architecture or exception
handlers usually will fix it up at runtime. Nevertheless it may trigger
a performance penality for some architectures. For details read the
"unaligned-memory-access" kernel documentation.
The patch below ensures that the ipv6 loopback and router addresses will
always be naturally aligned. This prevents the unaligned accesses for
all architectures.
Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: 034dfc5df99eb ("ipv6: export in6addr_loopback to modules")
Acked-by: Paolo Abeni <pabeni@redhat.com>
--
v2:
- Added A-b from Paolo
- Rephrased parts of commit message
- resent with [net] tag
---
diff --git a/net/ipv6/addrconf_core.c b/net/ipv6/addrconf_core.c
index 507a8353a6bd..813e009b4d0e 100644
--- a/net/ipv6/addrconf_core.c
+++ b/net/ipv6/addrconf_core.c
@@ -220,19 +220,26 @@ const struct ipv6_stub *ipv6_stub __read_mostly = &(struct ipv6_stub) {
EXPORT_SYMBOL_GPL(ipv6_stub);
/* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
-const struct in6_addr in6addr_loopback = IN6ADDR_LOOPBACK_INIT;
+const struct in6_addr in6addr_loopback __aligned(BITS_PER_LONG/8)
+ = IN6ADDR_LOOPBACK_INIT;
EXPORT_SYMBOL(in6addr_loopback);
-const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;
+const struct in6_addr in6addr_any __aligned(BITS_PER_LONG/8)
+ = IN6ADDR_ANY_INIT;
EXPORT_SYMBOL(in6addr_any);
-const struct in6_addr in6addr_linklocal_allnodes = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
+const struct in6_addr in6addr_linklocal_allnodes __aligned(BITS_PER_LONG/8)
+ = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
EXPORT_SYMBOL(in6addr_linklocal_allnodes);
-const struct in6_addr in6addr_linklocal_allrouters = IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;
+const struct in6_addr in6addr_linklocal_allrouters __aligned(BITS_PER_LONG/8)
+ = IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;
EXPORT_SYMBOL(in6addr_linklocal_allrouters);
-const struct in6_addr in6addr_interfacelocal_allnodes = IN6ADDR_INTERFACELOCAL_ALLNODES_INIT;
+const struct in6_addr in6addr_interfacelocal_allnodes __aligned(BITS_PER_LONG/8)
+ = IN6ADDR_INTERFACELOCAL_ALLNODES_INIT;
EXPORT_SYMBOL(in6addr_interfacelocal_allnodes);
-const struct in6_addr in6addr_interfacelocal_allrouters = IN6ADDR_INTERFACELOCAL_ALLROUTERS_INIT;
+const struct in6_addr in6addr_interfacelocal_allrouters __aligned(BITS_PER_LONG/8)
+ = IN6ADDR_INTERFACELOCAL_ALLROUTERS_INIT;
EXPORT_SYMBOL(in6addr_interfacelocal_allrouters);
-const struct in6_addr in6addr_sitelocal_allrouters = IN6ADDR_SITELOCAL_ALLROUTERS_INIT;
+const struct in6_addr in6addr_sitelocal_allrouters __aligned(BITS_PER_LONG/8)
+ = IN6ADDR_SITELOCAL_ALLROUTERS_INIT;
EXPORT_SYMBOL(in6addr_sitelocal_allrouters);
static void snmp6_free_dev(struct inet6_dev *idev)
next reply other threads:[~2024-01-26 8:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-26 8:32 Helge Deller [this message]
2024-01-30 11:50 ` [PATCH v2] [net] ipv6: Ensure natural alignment of const ipv6 loopback and router addresses patchwork-bot+netdevbpf
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