From patchwork Tue Apr 27 12:54:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 12226695 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3972C433ED for ; Tue, 27 Apr 2021 12:54:39 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A78566109E for ; Tue, 27 Apr 2021 12:54:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A78566109E Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.118431.224547 (Exim 4.92) (envelope-from ) id 1lbNER-000344-M3; Tue, 27 Apr 2021 12:54:27 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 118431.224547; Tue, 27 Apr 2021 12:54:27 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lbNER-00033x-JB; Tue, 27 Apr 2021 12:54:27 +0000 Received: by outflank-mailman (input) for mailman id 118431; Tue, 27 Apr 2021 12:54:26 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lbNEQ-00033m-RI for xen-devel@lists.xenproject.org; Tue, 27 Apr 2021 12:54:26 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 4090ac78-7dfd-47aa-a158-bc6b57c317a1; Tue, 27 Apr 2021 12:54:26 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 63310B1A4; Tue, 27 Apr 2021 12:54:25 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 4090ac78-7dfd-47aa-a158-bc6b57c317a1 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1619528065; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0I4gNzPs7QkUzQaZgNM9qNeznBTvZe1/bKfap9B3u8w=; b=I1oe92Je8Git0pBVz5wloJ4ZcuaPiMaX7eJBoYyZQdx0mtYAQ54W+1WpH7FSXlhvqcgJIs 4fkkcoxEaCh2Om/DNFlrYGGZNRTpTSqk0bQBE73DQTXILdvr2G+26UzAAL1asdq5Ngy8Jw y/ZvERG+fdVMDvdcI9Zci1cSX7k6jio= Subject: [PATCH 3/7] x86: re-work memset() From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , Wei Liu , =?utf-8?q?Roger_Pau_Monn=C3=A9?= References: <6d6da76c-ccc8-afa2-bd06-5ae132c354f2@suse.com> Message-ID: Date: Tue, 27 Apr 2021 14:54:24 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <6d6da76c-ccc8-afa2-bd06-5ae132c354f2@suse.com> Content-Language: en-US Move the function to its own assembly file. Having it in C just for the entire body to be an asm() isn't really helpful. Then have two flavors: A "basic" version using qword steps for the bulk of the operation, and an ERMS version for modern hardware, to be substituted in via alternatives patching. Signed-off-by: Jan Beulich --- We may want to consider branching over the REP STOSQ as well, if the number of qwords turns out to be zero. We may also want to consider using non-REP STOS{L,W,B} for the tail. --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -43,6 +43,7 @@ obj-$(CONFIG_INDIRECT_THUNK) += indirect obj-y += ioport_emulate.o obj-y += irq.o obj-$(CONFIG_KEXEC) += machine_kexec.o +obj-y += memset.o obj-y += mm.o x86_64/mm.o obj-$(CONFIG_HVM) += monitor.o obj-y += mpparse.o --- /dev/null +++ b/xen/arch/x86/memset.S @@ -0,0 +1,31 @@ +#include + +.macro memset + and $7, %edx + shr $3, %rcx + movzbl %sil, %esi + mov $0x0101010101010101, %rax + imul %rsi, %rax + mov %rdi, %rsi + rep stosq + or %edx, %ecx + jz 0f + rep stosb +0: + mov %rsi, %rax + ret +.endm + +.macro memset_erms + mov %esi, %eax + mov %rdi, %rsi + rep stosb + mov %rsi, %rax + ret +.endm + +ENTRY(memset) + mov %rdx, %rcx + ALTERNATIVE memset, memset_erms, X86_FEATURE_ERMS + .type memset, @function + .size memset, . - memset --- a/xen/arch/x86/string.c +++ b/xen/arch/x86/string.c @@ -22,19 +22,6 @@ void *(memcpy)(void *dest, const void *s return dest; } -void *(memset)(void *s, int c, size_t n) -{ - long d0, d1; - - asm volatile ( - "rep stosb" - : "=&c" (d0), "=&D" (d1) - : "a" (c), "1" (s), "0" (n) - : "memory"); - - return s; -} - void *(memmove)(void *dest, const void *src, size_t n) { long d0, d1, d2;