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Tue, 4 Aug 2026 11:37:36 +0000 (GMT) From: Heiko Carstens To: Harald Freudenberger , Holger Dengler , Herbert Xu Cc: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: [PATCH 1/3] s390/crypto: Rework ctr_aes_crypt() to remove conditional locking Date: Tue, 4 Aug 2026 13:37:34 +0200 Message-ID: <20260804113736.1423667-2-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260804113736.1423667-1-hca@linux.ibm.com> References: <20260804113736.1423667-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwODA0MDA5MCBTYWx0ZWRfX++kZP1pquKVD t/t+37fCUXjFwXA+st3Jf3TrLXGhD6kwt7pwYCusagMk7KC8PclyNrOCz4sDEQvy3OmDsvQ6UXM NPTkJhqvSpNXdWazjIHdSt8H1/1vIVY= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA0MDA5MCBTYWx0ZWRfX4LLoEbkE4wCt /C9yvxyKERzL5IW292wYduCN+M1ehACuB4SMphO3d/PqeOT8gn2pnPLDx59XWkDljPhMrX911q/ KBh9oSczuZ9H9Xor7TMkVfIW8eHneEE2WctQzpdm+nLfSuavSDpvP/N2rhfqryqiG7OJohcWAQ/ gYXrAGM2ZXwBKdKWh84DkYy53lkyBBHWcr9GX0vx10OTC2bRALhKpstYTRo7wQ/C4TwSC2Z0cNJ 2bs4TchJMIB5bHUkG8O7h69ru41H/UE1dDJdxfil7dZkMqyP0B8amCv+kAuO+7obOD5g0gw8ZFh UvHHgV04mRdKZsI/KlB0iB1/VPod1X0z8hYgiXI2nApJFJAgxqwpJNDxiFPUpc2IZerIdI9B0R3 AIrhcsXhe3eecW2uDwcubohKGpMuyROFv8uQqEBLZ4agB9QE1qNsoWvub/mXAcNwz+aO2dbztLp hH+4n8ZVx8wU0dRFRXQ== X-Authority-Analysis: v=2.4 cv=SI1ykuvH c=1 sm=1 tr=0 ts=6a71cf06 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=WSDBmxW9uEwFgrZJePAA:9 X-Proofpoint-ORIG-GUID: g0gSl_rI6OLYr8Oncl10UV8EXrqj3Chh X-Proofpoint-GUID: g0gSl_rI6OLYr8Oncl10UV8EXrqj3Chh X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-04_02,2026-08-03_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 bulkscore=0 suspectscore=0 impostorscore=0 spamscore=0 phishscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608040090 Clang's compiler based static context analysis does not work with locks that are conditionally taken like in ctr_aes_crypt(): arch/s390/crypto/aes_s390.c:585:13: warning: mutex 'ctrblk_lock' is not held on every path through here [-Wthread-safety-analysis] 585 | ctrptr = (n > AES_BLOCK_SIZE) ? ctrblk : walk.iv; | ^ Given that code which takes locks conditionally can be considered suboptimal rework ctr_aes_crypt() to get rid of this. Signed-off-by: Heiko Carstens --- arch/s390/crypto/aes_s390.c | 54 ++++++++++++++++++++++++------------- 1 file changed, 35 insertions(+), 19 deletions(-) diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c index 62edc66d5478..4b7e47423e89 100644 --- a/arch/s390/crypto/aes_s390.c +++ b/arch/s390/crypto/aes_s390.c @@ -562,37 +562,53 @@ static unsigned int __ctrblk_init(u8 *ctrptr, u8 *iv, unsigned int nbytes) return n; } +static int __ctr_aes_crypt(struct s390_aes_ctx *sctx, + struct skcipher_walk *walk, bool locked) +{ + unsigned int n, nbytes; + int ret = 0; + u8 *ctrptr; + + while ((nbytes = walk->nbytes) >= AES_BLOCK_SIZE) { + n = AES_BLOCK_SIZE; + if (nbytes >= 2 * AES_BLOCK_SIZE && locked) + n = __ctrblk_init(ctrblk, walk->iv, nbytes); + ctrptr = (n > AES_BLOCK_SIZE) ? ctrblk : walk->iv; + cpacf_kmctr(sctx->fc, sctx->key, walk->dst.virt.addr, + walk->src.virt.addr, n, ctrptr); + if (ctrptr == ctrblk) { + memcpy(walk->iv, ctrptr + n - AES_BLOCK_SIZE, + AES_BLOCK_SIZE); + } + crypto_inc(walk->iv, AES_BLOCK_SIZE); + ret = skcipher_walk_done(walk, nbytes - n); + } + + return ret; +} + static int ctr_aes_crypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct s390_aes_ctx *sctx = crypto_skcipher_ctx(tfm); - u8 buf[AES_BLOCK_SIZE], *ctrptr; struct skcipher_walk walk; - unsigned int n, nbytes; - int ret, locked; + u8 buf[AES_BLOCK_SIZE]; + unsigned int nbytes; + int ret; if (unlikely(!sctx->fc)) return fallback_skcipher_crypt(sctx, req, 0); - locked = mutex_trylock(&ctrblk_lock); - ret = skcipher_walk_virt(&walk, req, false); - while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) { - n = AES_BLOCK_SIZE; - if (nbytes >= 2*AES_BLOCK_SIZE && locked) - n = __ctrblk_init(ctrblk, walk.iv, nbytes); - ctrptr = (n > AES_BLOCK_SIZE) ? ctrblk : walk.iv; - cpacf_kmctr(sctx->fc, sctx->key, walk.dst.virt.addr, - walk.src.virt.addr, n, ctrptr); - if (ctrptr == ctrblk) - memcpy(walk.iv, ctrptr + n - AES_BLOCK_SIZE, - AES_BLOCK_SIZE); - crypto_inc(walk.iv, AES_BLOCK_SIZE); - ret = skcipher_walk_done(&walk, nbytes - n); - } - if (locked) + if (mutex_trylock(&ctrblk_lock)) { + ret = __ctr_aes_crypt(sctx, &walk, true); mutex_unlock(&ctrblk_lock); + } else { + ret = __ctr_aes_crypt(sctx, &walk, false); + } + + nbytes = walk.nbytes; /* * final block may be < AES_BLOCK_SIZE, copy only nbytes */ -- 2.53.0