From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by sourceware.org (Postfix) with ESMTP id 185663972472 for ; Fri, 27 Nov 2020 09:22:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 185663972472 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=huangpei@loongson.cn Received: from localhost.localdomain (unknown [182.149.161.68]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9Dxf9NlxcBfFHAXAA--.16578S5; Fri, 27 Nov 2020 17:22:54 +0800 (CST) From: Huang Pei To: Joseph Myers Cc: libc-alpha , Huacai Chen , Chenghua Xu Subject: [PATCH 3/3] mips: remove register spill Date: Fri, 27 Nov 2020 17:22:33 +0800 Message-Id: <20201127092233.29416-4-huangpei@loongson.cn> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201127092233.29416-1-huangpei@loongson.cn> References: <20201127092233.29416-1-huangpei@loongson.cn> X-CM-TRANSID: AQAAf9Dxf9NlxcBfFHAXAA--.16578S5 X-Coremail-Antispam: 1UD129KBjvJXoW7Ar4fWw4rAr43tryUKF48JFb_yoW8WF15pr 1fu3WUGrWrJryrCrnxur1UG3Z5Jwn2yr15Zr9I9F4YkrW5ur1rK39IvFyfGFy3tryfGF48 ZF1vgrn0grW5Za7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBS14x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JrWl82xGYIkIc2 x26xkF7I0E14v26r4j6ryUM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY02Avz4vE14v_GFWl42xK82 IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC2 0s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMI IF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF 0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87 Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfU1D73DUUUU X-CM-SenderInfo: xkxd0whshlqz5rrqw2lrqou0/ X-Spam-Status: No, score=-11.1 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_HELO_PASS, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Nov 2020 09:23:15 -0000 Before Linux/MIPS 2.6.36, kernel expected setting syscall number(aka "li v0, #sys_number") right precedes "syscall", so the kernel syscall restart sequence can use CP0 EPC - 4 to restart the syscall, because kernel DID NOT save v0 during syscall handling. Linux 2.6.36 canceled this restriction. See sysdeps/unix/sysv/linux/mips/{mips32/sysdep.h,mips64/sysdep.h,sysdep.h} Since glibc-2.24 the minimum kernel version is 3.2(much higer than 2.6.36), I think it is OK to remove the ugly register spill in syscall.S just because the old convention Signed-off-by: Huang Pei --- sysdeps/unix/sysv/linux/mips/mips64/syscall.S | 14 ++------------ 1 file changed, 2 insertions(+), 12 deletions(-) diff --git a/sysdeps/unix/sysv/linux/mips/mips64/syscall.S b/sysdeps/unix/sysv/linux/mips/mips64/syscall.S index aab1f389aa..089524a40b 100644 --- a/sysdeps/unix/sysv/linux/mips/mips64/syscall.S +++ b/sysdeps/unix/sysv/linux/mips/mips64/syscall.S @@ -27,14 +27,9 @@ .text NESTED (syscall, SZREG, ra) - .mask 0x00010000, -2 * SZREG + .mask 0x00000000, 0 .fmask 0x00000000, 0 - PTR_ADDIU sp, -2 * SZREG - cfi_adjust_cfa_offset (2 * SZREG) - REG_S s0, (sp) - cfi_rel_offset (s0, 0) - - move s0, a0 + move v0, a0 move a0, a1 /* shift arg1 - arg7. */ move a1, a2 move a2, a3 @@ -43,13 +38,8 @@ NESTED (syscall, SZREG, ra) move a5, a6 move a6, a7 - move v0, s0 /* Syscall number -> v0 */ syscall /* Do the system call. */ - REG_L s0, (sp) - cfi_restore (s0) - PTR_ADDIU sp, 2 * SZREG - cfi_adjust_cfa_offset (-2 * 2 * SZREG) bne a3, zero, L(error) ret -- 2.17.1