On Wed, 8 Jun 2022 09:19:20 +0100
Konstantin Ananyev <konstantin.v.anan...@yandex.ru> wrote:
> 07/06/2022 18:17, Stephen Hemminger пишет:
> > The function rte_memcpy can derference past source buffer which
> > will cause array out of bounds warnings. But there is no good reason
> > to use rte_memcpy instead of memcpy in this code. Memcpy is just
> > as fast for these small inputs, and compiler will optimize.
>
>
> AFAIK, rte_memcpy() will outperform memcpy() when _size_ parameter
> is a variable. Unfortunately that's exactly the case here.
> So not sure it is a good change, at least without extensive perf testing.
> BTW, if rte_memcpy() really access src buffer beyond it's boundaries,
> I think that's definitely a bug that needs to be fixed.
Yes and no.
IMHO DPDK should not in the C library business, and glibc etc should be
more optimized if necessary.
The ip_frag warning with rte_memcpy in full is:
[296/3606] Compiling C object lib/libr...a.p/ip_frag_rte_ipv4_fragmentation.c.o
In file included from /usr/lib/gcc/x86_64-linux-gnu/12/include/immintrin.h:43,
from /usr/lib/gcc/x86_64-linux-gnu/12/include/x86intrin.h:32,
from ../lib/eal/x86/include/rte_vect.h:31,
from ../lib/eal/x86/include/rte_memcpy.h:17,
from ../lib/ip_frag/rte_ipv4_fragmentation.c:8:
In function ‘_mm256_storeu_si256’,
inlined from ‘rte_mov32’ at ../lib/eal/x86/include/rte_memcpy.h:347:2,
inlined from ‘rte_mov128’ at ../lib/eal/x86/include/rte_memcpy.h:369:2,
inlined from ‘rte_memcpy_generic’ at
../lib/eal/x86/include/rte_memcpy.h:445:4,
inlined from ‘rte_memcpy’ at ../lib/eal/x86/include/rte_memcpy.h:853:10,
inlined from ‘__create_ipopt_frag_hdr’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:68:4,
inlined from ‘rte_ipv4_fragment_packet’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:242:16:
/usr/lib/gcc/x86_64-linux-gnu/12/include/avxintrin.h:935:8: warning: array
subscript ‘__m256i_u[1]’ is partly outside array bounds of ‘uint8_t[60]’ {aka
‘unsigned char[60]’} [-Warray-bounds]
935 | *__P = __A;
| ~~~~~^~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c: In function ‘rte_ipv4_fragment_packet’:
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [52, 60] into
object ‘ipopt_frag_hdr’ of size 60
122 | uint8_t ipopt_frag_hdr[IPV4_HDR_MAX_LEN];
| ^~~~~~~~~~~~~~
In function ‘_mm256_storeu_si256’,
inlined from ‘rte_mov32’ at ../lib/eal/x86/include/rte_memcpy.h:347:2,
inlined from ‘rte_mov128’ at ../lib/eal/x86/include/rte_memcpy.h:370:2,
inlined from ‘rte_memcpy_generic’ at
../lib/eal/x86/include/rte_memcpy.h:445:4,
inlined from ‘rte_memcpy’ at ../lib/eal/x86/include/rte_memcpy.h:853:10,
inlined from ‘__create_ipopt_frag_hdr’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:68:4,
inlined from ‘rte_ipv4_fragment_packet’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:242:16:
/usr/lib/gcc/x86_64-linux-gnu/12/include/avxintrin.h:935:8: warning: array
subscript [2, 3] is outside array bounds of ‘uint8_t[60]’ {aka ‘unsigned
char[60]’} [-Warray-bounds]
935 | *__P = __A;
| ~~~~~^~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c: In function ‘rte_ipv4_fragment_packet’:
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [84, 124] into
object ‘ipopt_frag_hdr’ of size 60
122 | uint8_t ipopt_frag_hdr[IPV4_HDR_MAX_LEN];
| ^~~~~~~~~~~~~~
In function ‘_mm256_storeu_si256’,
inlined from ‘rte_mov32’ at ../lib/eal/x86/include/rte_memcpy.h:347:2,
inlined from ‘rte_mov128’ at ../lib/eal/x86/include/rte_memcpy.h:371:2,
inlined from ‘rte_memcpy_generic’ at
../lib/eal/x86/include/rte_memcpy.h:445:4,
inlined from ‘rte_memcpy’ at ../lib/eal/x86/include/rte_memcpy.h:853:10,
inlined from ‘__create_ipopt_frag_hdr’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:68:4,
inlined from ‘rte_ipv4_fragment_packet’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:242:16:
/usr/lib/gcc/x86_64-linux-gnu/12/include/avxintrin.h:935:8: warning: array
subscript [3, 4] is outside array bounds of ‘uint8_t[60]’ {aka ‘unsigned
char[60]’} [-Warray-bounds]
935 | *__P = __A;
| ~~~~~^~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c: In function ‘rte_ipv4_fragment_packet’:
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [116, 156] into
object ‘ipopt_frag_hdr’ of size 60
122 | uint8_t ipopt_frag_hdr[IPV4_HDR_MAX_LEN];
| ^~~~~~~~~~~~~~
In function ‘_mm256_storeu_si256’,
inlined from ‘rte_mov32’ at ../lib/eal/x86/include/rte_memcpy.h:347:2,
inlined from ‘rte_mov64’ at ../lib/eal/x86/include/rte_memcpy.h:358:2,
inlined from ‘rte_memcpy_generic’ at
../lib/eal/x86/include/rte_memcpy.h:452:4,
inlined from ‘rte_memcpy’ at ../lib/eal/x86/include/rte_memcpy.h:853:10,
inlined from ‘__create_ipopt_frag_hdr’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:68:4,
inlined from ‘rte_ipv4_fragment_packet’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:242:16:
/usr/lib/gcc/x86_64-linux-gnu/12/include/avxintrin.h:935:8: warning: array
subscript ‘__m256i_u[1]’ is partly outside array bounds of ‘void[60]’
[-Warray-bounds]
935 | *__P = __A;
| ~~~~~^~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c: In function ‘rte_ipv4_fragment_packet’:
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [180, 240] into
object ‘ipopt_frag_hdr’ of size 60
122 | uint8_t ipopt_frag_hdr[IPV4_HDR_MAX_LEN];
| ^~~~~~~~~~~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [52, 60] into
object ‘ipopt_frag_hdr’ of size 60
In function ‘_mm256_storeu_si256’,
inlined from ‘rte_mov32’ at ../lib/eal/x86/include/rte_memcpy.h:347:2,
inlined from ‘rte_memcpy_generic’ at
../lib/eal/x86/include/rte_memcpy.h:457:4,
inlined from ‘rte_memcpy’ at ../lib/eal/x86/include/rte_memcpy.h:853:10,
inlined from ‘__create_ipopt_frag_hdr’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:68:4,
inlined from ‘rte_ipv4_fragment_packet’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:242:16:
/usr/lib/gcc/x86_64-linux-gnu/12/include/avxintrin.h:935:8: warning: array
subscript [2, 7] is outside array bounds of ‘void[60]’ [-Warray-bounds]
935 | *__P = __A;
| ~~~~~^~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c: In function ‘rte_ipv4_fragment_packet’:
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [148, 272] into
object ‘ipopt_frag_hdr’ of size 60
122 | uint8_t ipopt_frag_hdr[IPV4_HDR_MAX_LEN];
| ^~~~~~~~~~~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [148, 272] into
object ‘ipopt_frag_hdr’ of size 60
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [20, 60] into
object ‘ipopt_frag_hdr’ of size 60
In function ‘_mm256_storeu_si256’,
inlined from ‘rte_mov32’ at ../lib/eal/x86/include/rte_memcpy.h:347:2,
inlined from ‘rte_memcpy_generic’ at
../lib/eal/x86/include/rte_memcpy.h:458:4,
inlined from ‘rte_memcpy’ at ../lib/eal/x86/include/rte_memcpy.h:853:10,
inlined from ‘__create_ipopt_frag_hdr’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:68:4,
inlined from ‘rte_ipv4_fragment_packet’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:242:16:
/usr/lib/gcc/x86_64-linux-gnu/12/include/avxintrin.h:935:8: warning: array
subscript [2, 8] is outside array bounds of ‘void[60]’ [-Warray-bounds]
935 | *__P = __A;
| ~~~~~^~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c: In function ‘rte_ipv4_fragment_packet’:
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [149, 273] into
object ‘ipopt_frag_hdr’ of size 60
122 | uint8_t ipopt_frag_hdr[IPV4_HDR_MAX_LEN];
| ^~~~~~~~~~~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [149, 273] into
object ‘ipopt_frag_hdr’ of size 60
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [21, 60] into
object ‘ipopt_frag_hdr’ of size 60
In function ‘_mm256_storeu_si256’,
inlined from ‘rte_mov32’ at ../lib/eal/x86/include/rte_memcpy.h:347:2,
inlined from ‘rte_memcpy_generic’ at
../lib/eal/x86/include/rte_memcpy.h:438:3,
inlined from ‘rte_memcpy’ at ../lib/eal/x86/include/rte_memcpy.h:853:10,
inlined from ‘__create_ipopt_frag_hdr’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:68:4,
inlined from ‘rte_ipv4_fragment_packet’ at
../lib/ip_frag/rte_ipv4_fragmentation.c:242:16:
/usr/lib/gcc/x86_64-linux-gnu/12/include/avxintrin.h:935:8: warning: array
subscript ‘__m256i_u[1]’ is partly outside array bounds of ‘uint8_t[60]’ {aka
‘unsigned char[60]’} [-Warray-bounds]
935 | *__P = __A;
| ~~~~~^~~~~
../lib/ip_frag/rte_ipv4_fragmentation.c: In function ‘rte_ipv4_fragment_packet’:
../lib/ip_frag/rte_ipv4_fragmentation.c:122:17: note: at offset [37, 60] into
object ‘ipopt_frag_hdr’ of size 60
122 | uint8_t ipopt_frag_hdr[IPV4_HDR_MAX_LEN];
