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Mon, 12 Oct 2026 11:42:49 +0000 (GMT) Received: from tuxmaker.lnxne.boe (unknown [9.87.85.9]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 12 Oct 2026 11:42:49 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH 2/4] s390/percpu: Drop unused output register from arch_this_cpu_add() Date: Mon, 12 Oct 2026 13:42:47 +0200 Message-ID: <20261012114249.2898572-3-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261012114249.2898572-1-hca@linux.ibm.com> References: <20261012114249.2898572-1-hca@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: AW1haW4tMjYxMDEyMDA0NCBTYWx0ZWRfXwe1sPUz3lHUs xYblI83S67mRB+bn4pp3JHzglSzA0Ds2Hys5BPeLqfK7SmfGQxpUgshWz+ZJXqQjIme3+eOUK93 yToE1N4WZchz3SNJxQpV0PF7uIngWpPXEGZWmBuGTHi3wq0eSap9l25OQ3SIvMnFUSw+RQfjD4m o1kgsbYPQlFDK+Xk0YC5xhIyLlo68eUuoGbYyND1S1Gkk76KsCnBDD+JFS5L53Xx9Oq3hQj2Tne Rja9iW1Me587uCR5mJ741NyeKMNi634n6Tx4DKvIwrcer2ksOXvIpEEEluUo6wwBlA5yoKQav/F WvBGKm+eN5NlLD1Gx3n7RB2gAzYrvXwDMb1RBv9s4X4jKR4EhI3gZJgRtCAAicp8Ryq15OiEHWp olJA7/4vNSTr7/M8kjewpYZ9+ByPdbDRPeXLDIB8w31gHYrN7olM9E27ikYhdyz9yakx2+KbPIA UyKjkKsJFckd5q2SXXg== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDEyMDA0NCBTYWx0ZWRfXyhuTzGqmt1LX 06QluzVO89GPl+TI8eOm/Y3qaKj8uCsBQIa7AA90e00+i9+WlRu/yL9LIhtwC/KBh4QuxIEb9UJ REn8fucsjPNxycRJLs9tAqM1p41gkhM= X-Proofpoint-ORIG-GUID: z3tIrPPqGTXpCaQqhf-DxKVQxpDuDrbl X-Authority-Analysis: v=2.4 cv=a6KlZkSF c=1 sm=1 tr=0 ts=6accc7be cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=HZORN2dfYEM7eqIYgV4A:9 X-Proofpoint-GUID: z3tIrPPqGTXpCaQqhf-DxKVQxpDuDrbl 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=2026-10-12_03,2026-10-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 malwarescore=0 spamscore=0 suspectscore=0 clxscore=1015 phishscore=0 priorityscore=1501 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610120044 The laa/laag instructions return the old memory content, but arch_this_cpu_add() does not need it. Instead of allocating a dedicated output register old__ just to discard the returned value, change the val__ constraint from "d" to "+&d" so it is used as input/output register. This reduces register pressure. Signed-off-by: Heiko Carstens --- arch/s390/include/asm/percpu.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index dfab41b43b8b..fd0a3a9951ce 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -188,7 +188,7 @@ do { \ typedef typeof(pcp) pcp_op_T__; \ union register_pair rp__; \ pcp_op_T__ val__ = (val); \ - pcp_op_T__ old__, *ptr__; \ + pcp_op_T__ *ptr__; \ \ ptr__ = PERCPU_PTR(&(pcp)); \ if (__builtin_constant_p(val__) && \ @@ -209,12 +209,12 @@ do { \ asm_inline volatile( \ __PCPU_BEGIN("%[lcreg]","%[lcoff]","%[ptr__]", \ "%[pair__]","%N[pair__]") \ - op1 " %[old__],%[val__],0(%N[pair__])\n" \ + op1 " %[val__],%[val__],0(%N[pair__])\n" \ __PCPU_END("%[lcreg]") \ - : [old__] "=&d" (old__), [pair__] "=&a" (rp__.pair), \ + : [val__] "+&d" (val__), [pair__] "=&a" (rp__.pair), \ "+m" (*ptr__), \ "=m" (((struct lowcore *)0)->percpu_register) \ - : [val__] "d" (val__), [ptr__] "a" (ptr__), \ + : [ptr__] "a" (ptr__), \ [lcreg] "i" (LC_PERCPU_REGISTER), \ [lcoff] "i" (LC_PERCPU_OFFSET), \ "m" (((struct lowcore *)0)->percpu_offset) \ -- 2.53.0