On 17/04/2020 11:13, Thomas Monjalon wrote: > 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? > >
There may be, it could do with fresh eyes - Bruce/Konstantin? In the meantime I will send a v3 with push/pop so it is available as an option.
