Re: [dpdk-stable] [dpdk-dev] [PATCH] examples/l3fwd: fix unaligned memory access

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 25-Jul-19 3:01 PM, Lipiec, Herakliusz wrote:
> 
> 
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Aaron Conole
>> Sent: Thursday, July 25, 2019 2:28 PM
>> hgovindh <hariprasad.govindharajan@intel.com> writes:
>>
>>> Fix unaligned memory access when reading IPv6 header which leads to
>>> segmentation fault by changing aligned memory read to unaligned memory
>>> read.
>>>
>>> Bugzilla ID: 279
>>> Fixes: 64d3955de1de ("examples/l3fwd: fix ARM build")
>>> Cc: maciej.czekaj@caviumnetworks.com
>>> Cc: stable@dpdk.org
>>> Signed-off-by: hgovindh <hariprasad.govindharajan@intel.com>
>>> ---
>>>   examples/l3fwd/l3fwd_em.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/examples/l3fwd/l3fwd_em.c b/examples/l3fwd/l3fwd_em.c
>>> index fa8f82be6..f0c443dae 100644
>>> --- a/examples/l3fwd/l3fwd_em.c
>>> +++ b/examples/l3fwd/l3fwd_em.c
>>> @@ -285,7 +285,7 @@ em_get_ipv6_dst_port(void *ipv6_hdr, uint16_t
>> portid, void *lookup_struct)
>>>   	 * Get part of 5 tuple: dst IP address lower 96 bits
>>>   	 * and src IP address higher 32 bits.
>>>   	 */
>>> -	key.xmm[1] = *(xmm_t *)data1;
>>> +	key.xmm[1] = _mm_loadu_si128((xmm_t *)data1);
>>
>> Nak.  Please use a generic unaligned load, rather than an intel specific one.
>> Otherwise, supported platforms like arm64 will have broken builds.
>>
>> Additionally, which chip and compiler did you use to get this error?
> This comes from Bugzilla, the compiler used there is GCC 8.2.0 and the CPU is Intel Core i5,
> As far as I know this can also be reproduced on Intel Xeon, with GCC 8.3.0,
> in both cases its compiled with compiler optimizations disabled.

I have reproduced it with compiler optimizations enabled as well.

>>
>>>
>>>   	/*
>>>   	 * Get part of 5 tuple: dst port and src port
> 


-- 
Thanks,
Anatoly