5.4-stable review patch. If anyone has any objections, please let me know.
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From: Helge Deller deller@kernel.org
[ Upstream commit 60365049ccbacd101654a66ddcb299abfabd4fc5 ]
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 Link: https://lore.kernel.org/r/ZbNuFM1bFqoH-UoY@p100 Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/addrconf_core.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/net/ipv6/addrconf_core.c b/net/ipv6/addrconf_core.c index ea00ce3d4117..8494ee9679b4 100644 --- a/net/ipv6/addrconf_core.c +++ b/net/ipv6/addrconf_core.c @@ -204,19 +204,26 @@ 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)