From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C718FD11183 for ; Thu, 27 Nov 2025 12:36:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:CC: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=qdym5IeHw7I5kk48d6CR/tnfKDpc0G1zl2j3QUelC4I=; b=2p9U0fkSH9TqLJTl8KtN7bTltK UsBbzjYJ6dtBNhCl1/11i9EGoT3aDRLKxU7kiY020rfH9oYOAaYwfT9aj48Z6Mb0847QP8s07YxnQ cihn16s/QqUh5bAWei4gbbOQf/ro/34GmaXIkWxoMol9l7xXmSiDRmIPxqB3FL9m9SqbiTuDaeSBe JkGrKX/w1fw7ene6G3Q2AaNxn+Ej2lCVI5yZyRf03jM7u/ZllpbUC6APNG8F41jEvfqdWbCM/cABB 67x/GD/4HU7uWrHwuY+8arquSz7oJQuo6eRHKPHP7fwhYeBi0SdBZVuC979yyUp4ZXaOfgb+SlqGK QQ3EY8Cw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vObEv-0000000GZNl-19jb; Thu, 27 Nov 2025 12:36:49 +0000 Received: from canpmsgout11.his.huawei.com ([113.46.200.226]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vObEr-0000000GZMS-3jaa for linux-arm-kernel@lists.infradead.org; Thu, 27 Nov 2025 12:36:47 +0000 dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=qdym5IeHw7I5kk48d6CR/tnfKDpc0G1zl2j3QUelC4I=; b=QzrpXeDrGTUrKvr5L5/THoSnpQJB8zN9E7g6xw1FMoNBrxPc5+TgaRkPn2wctIyjdoLEHlT03 J1bf3lSmUGUCz/Q9HlekRDJaV0/5YTHZdr6EEUu4sda617GVsF/CF5IQop2fCNeQgkPTOu3jTNY abuLSHKw9mPnrvVv5ue8sQc= Received: from mail.maildlp.com (unknown [172.19.163.17]) by canpmsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4dHG8m1CrkzKm4J; Thu, 27 Nov 2025 20:34:48 +0800 (CST) Received: from dggpemf500011.china.huawei.com (unknown [7.185.36.131]) by mail.maildlp.com (Postfix) with ESMTPS id 6A7991A0188; Thu, 27 Nov 2025 20:36:37 +0800 (CST) Received: from huawei.com (10.90.53.73) by dggpemf500011.china.huawei.com (7.185.36.131) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 27 Nov 2025 20:36:36 +0800 From: Jinjie Ruan To: , , , , , , , , , , , , , CC: Subject: [PATCH 2/2] arm64: Avoid memcpy() for syscall_get_arguments() Date: Thu, 27 Nov 2025 20:36:30 +0800 Message-ID: <20251127123630.4149828-3-ruanjinjie@huawei.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251127123630.4149828-1-ruanjinjie@huawei.com> References: <20251127123630.4149828-1-ruanjinjie@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.90.53.73] X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To dggpemf500011.china.huawei.com (7.185.36.131) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251127_043646_234515_A6DBB625 X-CRM114-Status: UNSURE ( 8.92 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Do not use memcpy() to extract syscall arguments from struct pt_regs but rather just perform direct assignments. The performance benchmarks with Generic Entry patch[1] with audit on from perf bench basic syscall on kunpeng920 gives roughly a 1% performance uplift and also aligns the implementation with x86 and RISC-V. | Metric | W/O this patch | With this patch | Change | | ---------- | -------------- | --------------- | --------- | | Total time | 2.241 [sec] | 2.211 [sec] | ↓1.36% | | usecs/op | 0.224157 | 0.221146 | ↓1.36% | | ops/sec | 4,461,157 | 4,501,409 | ↑0.9% | Before: : aa0103e2 mov x2, x1 91002003 add x3, x0, #0x8 f9408804 ldr x4, [x0, #272] f8008444 str x4, [x2], #8 a9409404 ldp x4, x5, [x0, #8] a9009424 stp x4, x5, [x1, #8] a9418400 ldp x0, x1, [x0, #24] a9010440 stp x0, x1, [x2, #16] f9401060 ldr x0, [x3, #32] f9001040 str x0, [x2, #32] d65f03c0 ret d503201f nop After: a9408e82 ldp x2, x3, [x20, #8] 2a1603e0 mov w0, w22 f9400e84 ldr x4, [x20, #24] f9408a81 ldr x1, [x20, #272] 9401c4ba bl ffff800080215ca8 <__audit_syscall_entry> [1]: https://lore.kernel.org/all/20251126071446.3234218-1-ruanjinjie@huawei.com/ Signed-off-by: Jinjie Ruan --- arch/arm64/include/asm/syscall.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index f3853047c28e..f3564ba97f7e 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -82,9 +82,11 @@ static inline void syscall_get_arguments(struct task_struct *task, unsigned long *args) { args[0] = regs->orig_x0; - args++; - - memcpy(args, ®s->regs[1], 5 * sizeof(args[0])); + args[1] = regs->regs[1]; + args[2] = regs->regs[2]; + args[3] = regs->regs[3]; + args[4] = regs->regs[4]; + args[5] = regs->regs[5]; } static inline void syscall_set_arguments(struct task_struct *task, -- 2.34.1