From patchwork Tue Nov 5 18:30:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Haris Okanovic X-Patchwork-Id: 13863351 Received: from smtp-fw-33001.amazon.com (smtp-fw-33001.amazon.com [207.171.190.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CDDCC1DA62E; Tue, 5 Nov 2024 18:31:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=207.171.190.10 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730831518; cv=none; b=Bgj+GkB3aZFtXfPT1yn7GtGBZMmjzV8dDOFkzNwilwS8wJRAVUv+5HDtF/Ds70I7fiZhGpqe/sh5fCP+zvk3jSDYhfSenkSPFbWmwcKTn9dtWKo6PXAZIJ7ZPArxZLR8tJvmKxdiScja+lxTdTcoQ3d8SQLW8W1KRwqeCS+KKMk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730831518; c=relaxed/simple; bh=g3RI6aaPgmokkAIMFdNnpTUOZMxevHUOt3dhCDGsmO4=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UEdqFvS2zOon1Owf9Wq1rtxzi9BCwgCRTLkmPwuVcwLEW1WcsNXwCJ+trN2iNjO51B6tr0NHA+GccFsYZnZ1dAhk3jJdLBNEg1VQHBBF+2ZsVytXzFGDDDNP3uKrZQ37XNYKqa7RavEaCLaPqY+P01BLsOh8+0hX+omltATKMDc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=lgahfxVR; arc=none smtp.client-ip=207.171.190.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="lgahfxVR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1730831517; x=1762367517; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=aZOVkbd/aqSS6wL2tHU2ZYavLfm4wZ7pJZkt2CDBd7U=; b=lgahfxVR8Rr5NjZ0abKtetzZwqeJURjgg3Hv4o01q7EFbRgrC7j5nFfC R3DLEpPdkRzEg45t9i70KDfuaxB9L6zgLPTpk0VA/cwNURlwxNp+eXAPq HNDVRVsASJ6xIvcOAiQFr95WTXZnTCmnIIDoFS6oGOqaa7F3xVP9cTmUk A=; X-IronPort-AV: E=Sophos;i="6.11,260,1725321600"; d="scan'208";a="382672781" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.25.36.210]) by smtp-border-fw-33001.sea14.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Nov 2024 18:31:56 +0000 Received: from EX19MTAUWB001.ant.amazon.com [10.0.38.20:51046] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.10.37:2525] with esmtp (Farcaster) id 3cfefb00-6800-4172-8693-375f47215f5a; Tue, 5 Nov 2024 18:31:55 +0000 (UTC) X-Farcaster-Flow-ID: 3cfefb00-6800-4172-8693-375f47215f5a Received: from EX19D001UWA003.ant.amazon.com (10.13.138.211) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Tue, 5 Nov 2024 18:31:55 +0000 Received: from u34cccd802f2d52.amazon.com (10.106.239.17) by EX19D001UWA003.ant.amazon.com (10.13.138.211) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.35; Tue, 5 Nov 2024 18:31:50 +0000 From: Haris Okanovic To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH 2/5] arm64: add __READ_ONCE_EX() Date: Tue, 5 Nov 2024 12:30:38 -0600 Message-ID: <20241105183041.1531976-3-harisokn@amazon.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20241105183041.1531976-1-harisokn@amazon.com> References: <20240925232425.2763385-1-ankur.a.arora@oracle.com> <20241105183041.1531976-1-harisokn@amazon.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D033UWA004.ant.amazon.com (10.13.139.85) To EX19D001UWA003.ant.amazon.com (10.13.138.211) Perform an exclusive load, which atomically loads a word and arms the exclusive monitor to enable wfet()/wfe() accelerated polling. https://developer.arm.com/documentation/dht0008/a/arm-synchronization-primitives/exclusive-accesses/exclusive-monitors Signed-off-by: Haris Okanovic --- arch/arm64/include/asm/readex.h | 46 +++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 arch/arm64/include/asm/readex.h diff --git a/arch/arm64/include/asm/readex.h b/arch/arm64/include/asm/readex.h new file mode 100644 index 000000000000..51963c3107e1 --- /dev/null +++ b/arch/arm64/include/asm/readex.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Based on arch/arm64/include/asm/rwonce.h + * + * Copyright (C) 2020 Google LLC. + * Copyright (C) 2024 Amazon.com, Inc. or its affiliates. + */ + +#ifndef __ASM_READEX_H +#define __ASM_READEX_H + +#define __LOAD_EX(sfx, regs...) "ldaxr" #sfx "\t" #regs + +#define __READ_ONCE_EX(x) \ +({ \ + typeof(&(x)) __x = &(x); \ + int atomic = 1; \ + union { __unqual_scalar_typeof(*__x) __val; char __c[1]; } __u; \ + switch (sizeof(x)) { \ + case 1: \ + asm volatile(__LOAD_EX(b, %w0, %1) \ + : "=r" (*(__u8 *)__u.__c) \ + : "Q" (*__x) : "memory"); \ + break; \ + case 2: \ + asm volatile(__LOAD_EX(h, %w0, %1) \ + : "=r" (*(__u16 *)__u.__c) \ + : "Q" (*__x) : "memory"); \ + break; \ + case 4: \ + asm volatile(__LOAD_EX(, %w0, %1) \ + : "=r" (*(__u32 *)__u.__c) \ + : "Q" (*__x) : "memory"); \ + break; \ + case 8: \ + asm volatile(__LOAD_EX(, %0, %1) \ + : "=r" (*(__u64 *)__u.__c) \ + : "Q" (*__x) : "memory"); \ + break; \ + default: \ + atomic = 0; \ + } \ + atomic ? (typeof(*__x))__u.__val : (*(volatile typeof(__x))__x);\ +}) + +#endif