From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 35AC33858C1F for ; Tue, 11 Apr 2023 13:50:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 35AC33858C1F Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681221008; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6lnuEAEPPCbfyIaOtraR1XstjOZBfaWhtGPS8LAkfNI=; b=DE2prGjUKo3DnCAO0YG2xeOd8quot+0OTbam6e5K1E/VkHA006D0ZdoPFgMnU8ms8aRVz8 0KGcu39PtTqit/2rGvtdnY3yjV6Gm/15l1C52DZ0wo80MhDmnh1T9NRIm9DWp3XguYwH27 oGj5y/1e+8LwGYi/2KcAYTh0xuuFLv0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-198-fg_a0n-tOCOqOfR440nH1A-1; Tue, 11 Apr 2023 09:50:06 -0400 X-MC-Unique: fg_a0n-tOCOqOfR440nH1A-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DC9AF185A7A2 for ; Tue, 11 Apr 2023 13:50:05 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.48]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 57189492B00; Tue, 11 Apr 2023 13:50:05 +0000 (UTC) From: Florian Weimer To: Joe Simmons-Talbott via Libc-alpha Cc: Joe Simmons-Talbott Subject: Re: [PATCH 2/2] aarch64: Set the syscall register right before doing the syscall. References: <20230411133004.2268170-1-josimmon@redhat.com> <20230411133004.2268170-3-josimmon@redhat.com> Date: Tue, 11 Apr 2023 15:50:04 +0200 In-Reply-To: <20230411133004.2268170-3-josimmon@redhat.com> (Joe Simmons-Talbott via Libc-alpha's message of "Tue, 11 Apr 2023 09:30:04 -0400") Message-ID: <87h6tmil4j.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: * Joe Simmons-Talbott via Libc-alpha: > ({ long _sys_result; \ > { \ > LOAD_ARGS_##nr (args) \ > register long _x8 asm ("x8") = (name); \ > + if (__builtin_constant_p(name)) \ > + asm volatile ("mov x8, " MSTR(name) ";" \ > + : /* no output */ : "i" (name) : "x8"); \ > asm volatile ("svc 0 // syscall " # name \ > : "=r" (_x0) : "r"(_x8) ASM_ARGS_##nr : "memory"); \ > _sys_result = _x0; \ I think you should do this in a single assembler statement, load the constant only once. Thanks, Florian