From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 52489 invoked by alias); 22 Oct 2019 08:00:34 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 52452 invoked by uid 89); 22 Oct 2019 08:00:34 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-22.9 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.1 spammy=Fifth, Buy, buy, fifth X-HELO: mx0a-001b2d01.pphosted.com To: GNU C Library From: Stefan Liebler Subject: [PATCH] S390: Remove not needed stack frame in syscall function. Date: Tue, 22 Oct 2019 08:00:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="------------1C8B98B762D990593C872162" x-cbid: 19102208-0016-0000-0000-000002BB542A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19102208-0017-0000-0000-0000331C8D10 Message-Id: <0e66f775-9669-ff29-e605-195b79382b3e@linux.ibm.com> X-SW-Source: 2019-10/txt/msg00633.txt.bz2 This is a multi-part message in MIME format. --------------1C8B98B762D990593C872162 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-length: 285 Hi, As an svc invocation does not clobber any user space registers despite of the return value r2 and it does not need a special stack frame. This patch gets rid of the extra frame. We just have to save and restore r6 and r7 as those are preserved across function calls. Bye, Stefan --------------1C8B98B762D990593C872162 Content-Type: text/x-patch; name="20191017_s390_syscall.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="20191017_s390_syscall.patch" Content-length: 3759 commit 1349ca6793627f62d0fe96d5e0891e2e0166ba90 Author: Stefan Liebler Date: Thu Oct 17 13:49:03 2019 +0200 S390: Remove not needed stack frame in syscall function. As an svc invocation does not clobber any user space registers despite of the return value r2 and it does not need a special stack frame. This patch gets rid of the extra frame. We just have to save and restore r6 and r7 as those are preserved across function calls. diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/syscall.S b/sysdeps/unix/sysv/linux/s390/s390-32/syscall.S index 69561d0b76..7ed36c0714 100644 --- a/sysdeps/unix/sysv/linux/s390/s390-32/syscall.S +++ b/sysdeps/unix/sysv/linux/s390/s390-32/syscall.S @@ -22,37 +22,19 @@ more information about the value -4095 used below.*/ ENTRY (syscall) - /* Save registers and setup stack. */ - stm %r6,%r15,24(%r15) /* save registers */ - cfi_offset (%r15, -36) - cfi_offset (%r14, -40) - cfi_offset (%r13, -44) - cfi_offset (%r12, -48) - cfi_offset (%r11, -52) - cfi_offset (%r10, -56) - cfi_offset (%r9, -60) - cfi_offset (%r8, -64) + stm %r6,%r7,24(%r15) /* save registers */ cfi_offset (%r7, -68) cfi_offset (%r6, -72) - lr %r1,%r15 - l %r0,4(0,%r15) /* load eos */ - ahi %r15,-96 /* buy stack space */ - cfi_adjust_cfa_offset (96) - st %r1,0(0,%r15) /* store back chain */ - st %r0,4(0,%r15) /* store eos */ lr %r1,%r2 /* move syscall number */ lr %r2,%r3 /* first parameter */ lr %r3,%r4 /* second parameter */ lr %r4,%r5 /* third parameter */ lr %r5,%r6 /* fourth parameter */ - l %r6,192(%r15) /* fifth parameter */ - l %r7,196(%r15) /* sixth parameter */ - + lm %r6,%r7,96(%r15) /* fifth / sixth parameter */ svc 0 - l %r15,0(%r15) /* load back chain. */ - cfi_adjust_cfa_offset (-96) - lm %r6,%r15,24(%r15) /* load registers. */ + + lm %r6,%r7,24(%r15) /* load registers. */ lhi %r0,-4095 clr %r2,%r0 /* check R2 for error */ diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/syscall.S b/sysdeps/unix/sysv/linux/s390/s390-64/syscall.S index bbe4d79848..442f9e4878 100644 --- a/sysdeps/unix/sysv/linux/s390/s390-64/syscall.S +++ b/sysdeps/unix/sysv/linux/s390/s390-64/syscall.S @@ -22,37 +22,19 @@ more information about the value -4095 used below.*/ ENTRY (syscall) - /* Save registers and setup stack. */ - stmg %r6,%r15,48(%r15) /* Save registers. */ - cfi_offset (%r15,-40) - cfi_offset (%r14,-48) - cfi_offset (%r13,-56) - cfi_offset (%r12,-64) - cfi_offset (%r11,-72) - cfi_offset (%r10,-80) - cfi_offset (%r9,-88) - cfi_offset (%r8,-96) + stmg %r6,%r7,48(%r15) /* Save registers. */ cfi_offset (%r7,-104) cfi_offset (%r6,-112) - lgr %r1,%r15 - lg %r0,8(%r15) /* Load eos. */ - aghi %r15,-160 /* Buy stack space. */ - cfi_adjust_cfa_offset (160) - stg %r1,0(%r15) /* Store back chain. */ - stg %r0,8(%r15) /* Store eos. */ lgr %r1,%r2 /* Move syscall number. */ lgr %r2,%r3 /* First parameter. */ lgr %r3,%r4 /* Second parameter. */ lgr %r4,%r5 /* Third parameter. */ lgr %r5,%r6 /* Fourth parameter. */ - lg %r6,320(%r15) /* Fifth parameter. */ - lg %r7,328(%r15) /* Sixth parameter. */ - + lmg %r6,%r7,160(%r15) /* Fifth / Sixth parameter. */ svc 0 - lg %r15,0(%r15) /* Load back chain. */ - cfi_adjust_cfa_offset (-160) - lmg %r6,%r15,48(%r15) /* Load registers. */ + + lmg %r6,%r7,48(%r15) /* Load registers. */ lghi %r0,-4095 clgr %r2,%r0 /* Check R2 for error. */ --------------1C8B98B762D990593C872162--