On Thu, 2023-01-19 at 14:05 +0300, Sergei Antonov wrote:
On Thu, 19 Jan 2023 at 11:18, Vyacheslav V. Mitrofanov v.v.mitrofanov@yadro.com wrote:
On Wed, 2023-01-18 at 20:52 +0300, Sergei Antonov wrote:
Commands "ping6" and "tftpboot ... -ipv6" did not work on ARM because machine code expects 4-byte alignment and some structures from net6.h are not aligned in memory.
Fix by adding __packed, since it is already used in this file.
Signed-off-by: Sergei Antonov saproj@gmail.com
include/net6.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/net6.h b/include/net6.h index 9b3de028e6dc..2d7c5a096046 100644 --- a/include/net6.h +++ b/include/net6.h @@ -24,7 +24,7 @@ struct in6_addr { #define s6_addr in6_u.u6_addr8 #define s6_addr16 in6_u.u6_addr16 #define s6_addr32 in6_u.u6_addr32 -}; +} __packed;
#define IN6ADDRSZ sizeof(struct in6_addr) #define INETHADDRSZ sizeof(net_ethaddr) @@ -62,7 +62,7 @@ struct ip6_hdr { u8 hop_limit; struct in6_addr saddr; struct in6_addr daddr; -}; +} __packed; #define IP6_HDR_SIZE (sizeof(struct ip6_hdr))
/* struct udp_hdr - User Datagram Protocol header */ @@ -164,7 +164,7 @@ struct icmp6hdr { #define icmp6_addrconf_managed icmp6_dataun.u_nd_ra.managed #define icmp6_addrconf_other icmp6_dataun.u_nd_ra.other #define icmp6_rt_lifetime icmp6_dataun.u_nd_ra.rt_lifetime -}; +} __packed;
extern struct in6_addr const net_null_addr_ip6; /* NULL IPv6 address */ extern struct in6_addr net_gateway6; /* Our gateways IPv6 address
*/
2.34.1
Hello, Sergei!
I didn't get you a little bit. You mean holes between fields of structures or alignment of the beginning?
No, it is not about holes between fields. It is about the address at which a structure is placed in memory. In combination with store merging it leads to unaligned memory access. At least for struct ip6_hdr, which I studied using assembly listing files. The struct ip6_hdr is not placed at 4-byte aligned address because it is 14 bytes off from the beginning of the Ethernet packet.
Also see how the corresponding IPv4 struct ip_hdr from net.h was fixed by commit 704f3acfcf553. I should have referred to it in my commit description.
I got you. It makes sense. Thanks!
Reviewed-by: Viacheslav Mitrofanov v.v.mitrofanov@yadro.com