17/04/2020 11:33, Bruce Richardson: > On Thu, Apr 16, 2020 at 07:45:49PM +0100, Kevin Traynor wrote: > > stringop-overflow warns when it sees a possible overflow > > in a string operation. > > > > In the rte_memcpy functions different branches are taken > > depending on the size. stringop-overflow is raised for the > > branches in the function where it sees the static size of the > > src could be overflowed. > > > > However, in reality a correct size argument and in some cases > > dynamic allocation would ensure that this does not happen. > > > > For example, in the case below for key, the correct path will be > > chosen in rte_memcpy_generic at runtime based on the size argument > > but as some paths in the function could lead to a cast to 32 bytes > > a warning is raised. > > > > In function ‘_mm256_storeu_si256’, > > inlined from ‘rte_memcpy_generic’ > > at ../lib/librte_eal/common/include/arch/x86/rte_memcpy.h:315:2, > > inlined from ‘iavf_configure_rss_key’ > > at ../lib/librte_eal/common/include/arch/x86/rte_memcpy.h:869:10: > > > > /usr/lib/gcc/x86_64-redhat-linux/10/include/avxintrin.h:928:8: > > warning: writing 32 bytes into a region of size 1 [-Wstringop-overflow=] > > 928 | *__P = __A; > > | ~~~~~^~~~~ > > In file included > > from ../drivers/net/iavf/../../common/iavf/iavf_prototype.h:10, > > from ../drivers/net/iavf/iavf.h:9, > > from ../drivers/net/iavf/iavf_vchnl.c:22: > > > > ../drivers/net/iavf/iavf_vchnl.c: > > In function ‘iavf_configure_rss_key’: > > > > ../drivers/net/iavf/../../common/iavf/virtchnl.h:508:5: > > note: at offset 0 to object ‘key’ with size 1 declared here > > 508 | u8 key[1]; /* RSS hash key, packed bytes */ > > | ^~~ > > > > Ignore the stringop-overflow warnings for rte_memcpy.h functions. > > > > Bugzilla ID: 394 > > Bugzilla ID: 421 > > > > Signed-off-by: Kevin Traynor <ktray...@redhat.com> [...] > > --- a/lib/librte_eal/x86/include/rte_memcpy.h > > +++ b/lib/librte_eal/x86/include/rte_memcpy.h > > +#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 100000) > > +#pragma GCC diagnostic ignored "-Wstringop-overflow" > > +#endif > > Does this permanently need to be disabled for all compilation units > including rte_memcpy.h, or can it be used with a push/pop set of pragmas to > only disable for the required functions?
Even better, isn't there a solution in memcpy code?
