From nobody Fri Apr 10 20:53:40 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6585C46467 for ; Tue, 27 Dec 2022 03:09:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229589AbiL0DJL (ORCPT ); Mon, 26 Dec 2022 22:09:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229772AbiL0DIw (ORCPT ); Mon, 26 Dec 2022 22:08:52 -0500 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21BDF264C for ; Mon, 26 Dec 2022 19:08:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672110531; x=1703646531; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=cWbMXq+BulH9gIMaAKVyjGjPeJ6XOcZ2RXQodh7xORI=; b=LaH+MN7ps6xJB5ynzm204FXQ8IRzOinh24arYS6jyaMrQizlLPteoXD4 LFtF5e9/g//pMsHMacbRkebUUtC0sz0H4mbcsIWiHRC8ttF6mandkDjfl mhzRcaWkZKlHFFttE7OODZiveh1evk7v0ASIFabgKT2qbD5w7PnlU6HKl mJmqeZ5BljWscLXcCrw3pNwAGm0+mRRzewgTVYnx1ej7X31sS4F0gGTim Gpd5YRRrOsman9AlOmxSWx+oMsEU5T4bQWgjzsIMZ/R7PcO8pbKVyKF9C ukBnGfT6l/Re9OodXf853N0Gd2lFJUXf+hEuEqV3rv9Mdx6y0MYmTO+DL A==; X-IronPort-AV: E=McAfee;i="6500,9779,10572"; a="300994696" X-IronPort-AV: E=Sophos;i="5.96,277,1665471600"; d="scan'208";a="300994696" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Dec 2022 19:08:50 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10572"; a="741605217" X-IronPort-AV: E=Sophos;i="5.96,277,1665471600"; d="scan'208";a="741605217" Received: from ppogotov-mobl.ger.corp.intel.com (HELO box.shutemov.name) ([10.252.62.152]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Dec 2022 19:08:46 -0800 Received: by box.shutemov.name (Postfix, from userid 1000) id BEEAE10BBB4; Tue, 27 Dec 2022 06:08:36 +0300 (+03) From: "Kirill A. Shutemov" To: Dave Hansen , Andy Lutomirski , Peter Zijlstra Cc: x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Bharata B Rao , Jacob Pan , Ashok Raj , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv13 07/16] x86/mm: Reduce untagged_addr() overhead until the first LAM user Date: Tue, 27 Dec 2022 06:08:20 +0300 Message-Id: <20221227030829.12508-8-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.38.2 In-Reply-To: <20221227030829.12508-1-kirill.shutemov@linux.intel.com> References: <20221227030829.12508-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Use static key to reduce untagged_addr() overhead. The key only gets enabled when the first process enables LAM. Signed-off-by: Kirill A. Shutemov --- arch/x86/include/asm/uaccess.h | 9 +++++++-- arch/x86/kernel/process_64.c | 4 ++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index cbb463e9344f..1d931c7f6741 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -23,6 +23,8 @@ static inline bool pagefault_disabled(void); #endif =20 #ifdef CONFIG_X86_64 +DECLARE_STATIC_KEY_FALSE(tagged_addr_key); + /* * Mask out tag bits from the address. * @@ -31,8 +33,11 @@ static inline bool pagefault_disabled(void); */ #define __untagged_addr(mm, addr) ({ \ u64 __addr =3D (__force u64)(addr); \ - s64 sign =3D (s64)__addr >> 63; \ - __addr &=3D READ_ONCE((mm)->context.untag_mask) | sign; \ + if (static_branch_likely(&tagged_addr_key)) { \ + s64 sign =3D (s64)__addr >> 63; \ + u64 mask =3D READ_ONCE((mm)->context.untag_mask); \ + __addr &=3D mask | sign; \ + } \ (__force __typeof__(addr))__addr; \ }) =20 diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index fef127ed79b6..09e7f3d3fb5c 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -743,6 +743,9 @@ static long prctl_map_vdso(const struct vdso_image *ima= ge, unsigned long addr) } #endif =20 +DEFINE_STATIC_KEY_FALSE(tagged_addr_key); +EXPORT_SYMBOL_GPL(tagged_addr_key); + #define LAM_U57_BITS 6 =20 static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr= _bits) @@ -773,6 +776,7 @@ static int prctl_enable_tagged_addr(struct mm_struct *m= m, unsigned long nr_bits) =20 mmap_write_unlock(mm); =20 + static_branch_enable(&tagged_addr_key); return 0; } =20 --=20 2.38.2