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From: Thomas Monjalon <thomas@monjalon.net>
To: Kevin Traynor <ktraynor@redhat.com>,
	Bruce Richardson <bruce.richardson@intel.com>
Cc: dev@dpdk.org, Gavin.Hu@arm.com, ravi1.kumar@amd.com,
	g.singh@nxp.com, hemant.agrawal@nxp.com, akhil.goyal@nxp.com,
	johndale@cisco.com, hyonkim@cisco.com, jingjing.wu@intel.com,
	wenzhuo.lu@intel.com, rmody@marvell.com, shshaikh@marvell.com,
	matan@mellanox.com, shahafs@mellanox.com,
	declan.doherty@intel.com, cristian.dumitrescu@intel.com,
	konstantin.ananyev@intel.com, zhihong.wang@intel.com
Subject: Re: [dpdk-dev] [PATCH v2] x86/eal: gcc 10 ignore stringop-overflow warnings
Date: Fri, 17 Apr 2020 12:13:29 +0200	[thread overview]
Message-ID: <3643335.9fHWaBTJ5E@thomas> (raw)
In-Reply-To: <20200417093358.GB1701@bricha3-MOBL.ger.corp.intel.com>

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 <ktraynor@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?



  reply	other threads:[~2020-04-17 10:13 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25 14:11 [dpdk-dev] [RFC 0/2] gcc 10 disable stringop-overflow warning Kevin Traynor
2020-03-25 14:11 ` [dpdk-dev] [RFC 1/2] meson: gcc 10 disable stringop-overflow warnings Kevin Traynor
2020-03-25 14:11 ` [dpdk-dev] [RFC 2/2] mk: " Kevin Traynor
2020-03-25 14:18 ` [dpdk-dev] [RFC 0/2] gcc 10 disable stringop-overflow warning Thomas Monjalon
2020-03-31 14:08   ` Kevin Traynor
2020-03-31 14:53     ` Stephen Hemminger
2020-04-01 11:33       ` Kevin Traynor
2020-04-07 16:27 ` [dpdk-dev] [PATCH] build: gcc 10 disable stringop-overflow warnings Kevin Traynor
2020-04-10 10:51   ` Kevin Traynor
2020-04-10 13:23     ` Bruce Richardson
2020-04-16 18:43       ` Kevin Traynor
2020-04-16 18:45   ` [dpdk-dev] [PATCH v2] x86/eal: gcc 10 ignore " Kevin Traynor
2020-04-17  9:33     ` Bruce Richardson
2020-04-17 10:13       ` Thomas Monjalon [this message]
2020-04-17 14:50         ` Kevin Traynor
2020-04-17 12:40       ` Kevin Traynor
2020-04-17 15:43     ` [dpdk-dev] [PATCH v3] " Kevin Traynor
2020-05-06  9:20       ` David Marchand

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