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Thu, 19 Mar 2026 12:05:04 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Juergen Christ Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH v2 4/9] s390/percpu: Use new percpu code section for arch_this_cpu_add() Date: Thu, 19 Mar 2026 13:04:58 +0100 Message-ID: <20260319120503.4046659-5-hca@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260319120503.4046659-1-hca@linux.ibm.com> References: <20260319120503.4046659-1-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: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: dFfITtoFiG-2wNVHgkPN9CpOv8rBStbx X-Proofpoint-ORIG-GUID: dFfITtoFiG-2wNVHgkPN9CpOv8rBStbx X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzE5MDA5NCBTYWx0ZWRfXxixSp/4wNlGf vINae4NNjm5LOj9bC126OMHLK5Fb7GO/FUpFWB2vVtr8DTEpHVpZljxJu2P74iJDpHA0MPp7kYr vw1G8zlBXrHNsB9GCCb21oUehrpE1RgF9w2pgo5/n0I3CCwkrbK9VuoCQvpzfFYe31RADbOuPiP 8+oYCzA41GTQ6cl9z+/Gmo+om/7+GNlCVKZdESzoFqdm+Tb9gOFgs+AbN1MAMXf5F/2E4NCDWvp JFfEapCJ6aRK/kdAn9QKs1Edq/9TfhEJgmspV75lMTR3gGhxZEY/9dXwmuIpDK9Mydf4zU3TXlE 5Y6MQn0ZDScCdTiDHQiT+GMKNBLZffkmax/JvSjgxh4B6HaiuqhCliBbE08Bf0tSpPQt+1PWDy+ LEIUykHshemfo0agFtqHbNnVANfyJbJFweBjbmt09yEz4IqICvstDT8gKN38m0QGGNtl36Asgpg 8wMpoJObcWSKRr1JBmw== X-Authority-Analysis: v=2.4 cv=Hf8ZjyE8 c=1 sm=1 tr=0 ts=69bbe674 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=SujZmW7ZfIunUtho7CIA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-19_01,2026-03-19_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 bulkscore=0 suspectscore=0 priorityscore=1501 spamscore=0 adultscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603190094 Content-Type: text/plain; charset="utf-8" Convert arch_this_cpu_add() to make use of the new percpu code section infrastructure. With this the text size of the kernel image is reduced by ~76kb (defconfig). Also more than 5300 generated preempt_schedule_notrace() function calls within the kernel image (modules not counted) are removed. With: DEFINE_PER_CPU(long, foo); void bar(long a) { this_cpu_add(foo, a); } Old arch_this_cpu_add() looks like this: 00000000000000c0 : c0: c0 04 00 00 00 00 jgnop c0 c6: eb 01 03 a8 00 6a asi 936,1 cc: c4 18 00 00 00 00 lgrl %r1,cc ce: R_390_GOTENT foo+0x2 d2: e3 10 03 b8 00 08 ag %r1,952 d8: eb 22 10 00 00 e8 laag %r2,%r2,0(%r1) de: eb ff 03 a8 00 6e alsi 936,-1 e4: a7 a4 00 05 jhe ee e8: c0 f4 00 00 00 00 jg e8 ea: R_390_PC32DBL __s390_indirect_jump_r14+0x2 ee: c0 f4 00 00 00 00 jg ee f0: R_390_PLT32DBL preempt_schedule_notrace+0x2 New arch_this_cpu_add() looks like this: 00000000000000c0 : c0: c0 04 00 00 00 00 jgnop c0 c6: c4 38 00 00 00 00 lgrl %r3,c6 c8: R_390_GOTENT foo+0x2 cc: b9 04 00 43 lgr %r4,%r3 d0: eb 00 43 c0 00 52 mviy 960(%r4),0 d6: e3 40 03 b8 00 08 ag %r4,952 dc: eb 52 40 00 00 e8 laag %r5,%r2,0(%r4) e2: eb 00 03 c0 00 52 mviy 960,0 e8: c0 f4 00 00 00 00 jg e8 ea: R_390_PC32DBL __s390_indirect_jump_r14+0x2 Note that the conditional function call is removed. Signed-off-by: Heiko Carstens --- arch/s390/include/asm/percpu.h | 65 ++++++++++++++++++++++------------ 1 file changed, 43 insertions(+), 22 deletions(-) diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index 05eb91428b42..3c5364475e3e 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -127,28 +127,49 @@ =20 #else /* MARCH_HAS_Z196_FEATURES */ =20 -#define arch_this_cpu_add(pcp, val, op1, op2, szcast) \ -{ \ - typedef typeof(pcp) pcp_op_T__; \ - pcp_op_T__ val__ =3D (val); \ - pcp_op_T__ old__, *ptr__; \ - preempt_disable_notrace(); \ - ptr__ =3D raw_cpu_ptr(&(pcp)); \ - if (__builtin_constant_p(val__) && \ - ((szcast)val__ > -129) && ((szcast)val__ < 128)) { \ - asm volatile( \ - op2 " %[ptr__],%[val__]" \ - : [ptr__] "+Q" (*ptr__) \ - : [val__] "i" ((szcast)val__) \ - : "cc"); \ - } else { \ - asm volatile( \ - op1 " %[old__],%[val__],%[ptr__]" \ - : [old__] "=3Dd" (old__), [ptr__] "+Q" (*ptr__) \ - : [val__] "d" (val__) \ - : "cc"); \ - } \ - preempt_enable_notrace(); \ +#define arch_this_cpu_add(pcp, val, op1, op2, szcast) \ +{ \ + unsigned long lc_pcpr, lc_pcpo; \ + typedef typeof(pcp) pcp_op_T__; \ + pcp_op_T__ val__ =3D (val); \ + pcp_op_T__ old__, *ptr__; \ + \ + lc_pcpr =3D offsetof(struct lowcore, percpu_register); \ + lc_pcpo =3D offsetof(struct lowcore, percpu_offset); \ + ptr__ =3D PERCPU_PTR(&(pcp)); \ + if (__builtin_constant_p(val__) && \ + ((szcast)val__ > -129) && ((szcast)val__ < 128)) { \ + asm volatile( \ + MVIY_PERCPU("%[disppcpr]", "%[dispaltpcpr]", "%[ptr__]")\ + AG_ALT("%[disppcpo]", "%[dispaltpcpo]", "%[ptr__]") \ + op2 " 0(%[ptr__]),%[val__]\n" \ + MVIY_ALT("%[disppcpr]", "%[dispaltpcpr]", "%%r0") \ + : [ptr__] "+&a" (ptr__), "+m" (*ptr__), \ + "=3Dm" (((struct lowcore *)0)->percpu_register) \ + : [val__] "i" ((szcast)val__), \ + [disppcpr] "i" (lc_pcpr), \ + [disppcpo] "i" (lc_pcpo), \ + [dispaltpcpr] "i" (lc_pcpr + LOWCORE_ALT_ADDRESS), \ + [dispaltpcpo] "i" (lc_pcpo + LOWCORE_ALT_ADDRESS), \ + "m" (((struct lowcore *)0)->percpu_offset) \ + : "cc"); \ + } else { \ + asm volatile( \ + MVIY_PERCPU("%[disppcpr]", "%[dispaltpcpr]", "%[ptr__]")\ + AG_ALT("%[disppcpo]", "%[dispaltpcpo]", "%[ptr__]") \ + op1 " %[old__],%[val__],0(%[ptr__])\n" \ + MVIY_ALT("%[disppcpr]", "%[dispaltpcpr]", "%%r0") \ + : [old__] "=3D&d" (old__), \ + [ptr__] "+&a" (ptr__), "+m" (*ptr__), \ + "=3Dm" (((struct lowcore *)0)->percpu_register) \ + : [val__] "d" (val__), \ + [disppcpr] "i" (lc_pcpr), \ + [disppcpo] "i" (lc_pcpo), \ + [dispaltpcpr] "i" (lc_pcpr + LOWCORE_ALT_ADDRESS), \ + [dispaltpcpo] "i" (lc_pcpo + LOWCORE_ALT_ADDRESS), \ + "m" (((struct lowcore *)0)->percpu_offset) \ + : "cc"); \ + } \ } =20 #define this_cpu_add_4(pcp, val) arch_this_cpu_add(pcp, val, "laa", "asi",= int) --=20 2.51.0