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Thu, 13 Aug 2026 15:54:07 +0000 (GMT) Received: from funtu2.ibm.com (unknown [9.111.193.32]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 13 Aug 2026 15:54:07 +0000 (GMT) From: Harald Freudenberger To: dengler@linux.ibm.com, fcallies@linux.ibm.com, ifranzki@linux.ibm.com Cc: freude@linux.ibm.com, linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , linux-crypto@vger.kernel.org Subject: [PATCH v3 3/3] s390/crypto: Rewrite AES ctr mode to be prepared for context analysis Date: Thu, 13 Aug 2026 17:54:06 +0200 Message-ID: <20260813155406.50051-4-freude@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260813155406.50051-1-freude@linux.ibm.com> References: <20260813155406.50051-1-freude@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@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-Details-Enc: AW1haW4tMjYwODEzMDExMSBTYWx0ZWRfX0fQBiFZ5zdUm K6XuryYhoyWcpQK7IRgjj8h8cB1ppO5mKLs7XSaHC5kBggEPbxM37NjTKOiftSOsU87Sy138Bbk JdzQ+z0BywzM18Z72lKRy4twRjt2jNp6Llu+7xgo03kJ5KNHZT/Tq9ccgyly01x5CJ/7jzfFDku irwp3CHdyAqH5tRhLBfKQikH4iUM2tcF3vFth5B2E3Ygg5rfz+og2hjRe4eeY9+yQWjq/tZpUdu vIrx0PPTlgdfZ2aHCYmjPf9Sqyl0oeiciOS1NzJb+8l8M45WBZl67bh8cSf+fifVaqwVCKX5gxL Blir531p7CNu84ILw4ceayLk61vNIBJbxwXpYRls7UW8wJTR9niEhtsaBJils+3XNjAXJL48weV g74j4cIsl4tN135L0Bt8eZEQYFIgy/c9coAw0GPQ6+CeSrXXhlvoRXA7dq6MIylz2s/nuHNYA3i e11+0YPX8nsfGpbgLEQ== X-Proofpoint-ORIG-GUID: 2HTq1IJi6eNyLl6aYw9bUHrgVzJN2XW6 X-Proofpoint-Spam-Info: AW1haW4tMjYwODEzMDExMSBTYWx0ZWRfX+xR81q+2rDL/ Rhp4NtV/wYed6qOhVXI1+8kzr1jBaZzjS//9RTlVd/Ah4I04WDFCy3QjzQJcLNtUyVBzo4Sc1RK CBFXaXwECs9Hzp2p5ewIMBloKtGMVPU= X-Authority-Analysis: v=2.4 cv=IfK3n2qa c=1 sm=1 tr=0 ts=6a7de8a4 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=e91DsxHqfR-orwYc_R4A:9 X-Proofpoint-GUID: 2HTq1IJi6eNyLl6aYw9bUHrgVzJN2XW6 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=2026-08-13_05,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 adultscore=0 malwarescore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608130111 The AES ctr implementation produces a warning when used with clang and CONTEXT_ANALYIS enabled: 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; | ^ arch/s390/crypto/aes_s390.c:577:11: note: mutex acquired here 577 | locked = mutex_trylock(&ctrblk_lock); | ^ Rewrite and reorganize the code such that the clang compiler's needs are fulfilled with keeping the compatibility, performance and correctness of the crypto algorithm. Also cover a finding from Sashiko about that the mutex_trylock() may be invoked from a softirq context. So add a check to make sure only in process context try to lock the mutex. Signed-off-by: Harald Freudenberger Suggested-by: Heiko Carstens --- arch/s390/crypto/aes_s390.c | 60 +++++++++++++++++++++++-------------- 1 file changed, 38 insertions(+), 22 deletions(-) diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c index 10561aa687c7..8295cb3fc56c 100644 --- a/arch/s390/crypto/aes_s390.c +++ b/arch/s390/crypto/aes_s390.c @@ -562,46 +562,62 @@ 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 (!ret && ((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]; + 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 (!ret && ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE)) { - n = AES_BLOCK_SIZE; + if (ret) + return ret; - 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 (in_task() && mutex_trylock(&ctrblk_lock)) { + /* process context and mutex acquired */ + ret = __ctr_aes_crypt(sctx, &walk, true); mutex_unlock(&ctrblk_lock); + } else { + ret = __ctr_aes_crypt(sctx, &walk, false); + } /* * final block may be < AES_BLOCK_SIZE, copy only nbytes */ - if (!ret && nbytes) { + if (!ret && walk.nbytes) { memset(buf, 0, AES_BLOCK_SIZE); - memcpy(buf, walk.src.virt.addr, nbytes); + memcpy(buf, walk.src.virt.addr, walk.nbytes); cpacf_kmctr(sctx->fc, sctx->key, buf, buf, AES_BLOCK_SIZE, walk.iv); - memcpy(walk.dst.virt.addr, buf, nbytes); + memcpy(walk.dst.virt.addr, buf, walk.nbytes); crypto_inc(walk.iv, AES_BLOCK_SIZE); ret = skcipher_walk_done(&walk, 0); memzero_explicit(buf, sizeof(buf)); -- 2.43.0