From: behanw@converseincode.com Subject: [PATCH RFC 3/6] crypto: LLVMLinux: Remove VLAIS usage from libcrc32c.c Date: Tue, 2 Sep 2014 15:32:30 -0700 Message-ID: <1409697153-7006-4-git-send-email-behanw@converseincode.com> References: <1409697153-7006-1-git-send-email-behanw@converseincode.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: akpm@linux-foundation.org, james.l.morris@oracle.com, john.johansen@canonical.com, linux-btrfs@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, linux-security-module@vger.kernel.org, neilb@suse.de, serge@hallyn.com, torvalds@linux-foundation.org, =?UTF-8?q?Jan-Simon=20M=C3=B6ller?= , Behan Webster , pageexec@freemail.hu To: agk@redhat.com, clm@fb.com, davem@davemloft.net, dm-devel@redhat.com, fabf@skynet.be, herbert@gondor.apana.org.au, jbacik@fb.com, snitzer@redhat.com Return-path: In-Reply-To: <1409697153-7006-1-git-send-email-behanw@converseincode.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org =46rom: Jan-Simon M=C3=B6ller The use of variable length arrays in structs (VLAIS) in the Linux Kerne= l code precludes the use of compilers which don't implement VLAIS (for instanc= e the Clang compiler). This patch instead allocates the appropriate amount of= memory using an char array. struct shash_desc contains a flexible array member member ctx declared = with CRYPTO_MINALIGN_ATTR, so sizeof(struct shash_desc) aligns the beginning of the array declared after struct shash_desc with long long. No trailing padding is required because it is not a struct type that ca= n be used in an array. The CRYPTO_MINALIGN_ATTR is required so that desc is aligned with long = long as would be the case for a struct containing a member with CRYPTO_MINALIGN_ATTR. Signed-off-by: Jan-Simon M=C3=B6ller Signed-off-by: Behan Webster Cc: pageexec@freemail.hu --- lib/libcrc32c.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/lib/libcrc32c.c b/lib/libcrc32c.c index b3131f5..03f2cf3 100644 --- a/lib/libcrc32c.c +++ b/lib/libcrc32c.c @@ -41,20 +41,20 @@ static struct crypto_shash *tfm; =20 u32 crc32c(u32 crc, const void *address, unsigned int length) { - struct { - struct shash_desc shash; - char ctx[crypto_shash_descsize(tfm)]; - } desc; + char desc[sizeof(struct shash_desc) + + crypto_shash_descsize(tfm)] CRYPTO_MINALIGN_ATTR; + struct shash_desc *shash =3D (struct shash_desc *)desc; + u32 *ctx =3D (u32 *)shash_desc_ctx(shash); int err; =20 - desc.shash.tfm =3D tfm; - desc.shash.flags =3D 0; - *(u32 *)desc.ctx =3D crc; + shash->tfm =3D tfm; + shash->flags =3D 0; + *ctx =3D crc; =20 - err =3D crypto_shash_update(&desc.shash, address, length); + err =3D crypto_shash_update(shash, address, length); BUG_ON(err); =20 - return *(u32 *)desc.ctx; + return *ctx; } =20 EXPORT_SYMBOL(crc32c); --=20 1.9.1