From nobody Mon Sep 15 18:06:24 2025 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 AC5A0C5479D for ; Wed, 11 Jan 2023 13:25:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238256AbjAKNZq (ORCPT ); Wed, 11 Jan 2023 08:25:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234175AbjAKNYD (ORCPT ); Wed, 11 Jan 2023 08:24:03 -0500 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3D2F25EF for ; Wed, 11 Jan 2023 05:24:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1673443442; x=1704979442; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=yKZbUwdFl1OELkYDtSril3bPVHQFFQ9B8sbyyX7BAAY=; b=EQ2ZbevFjOEvN9UyTZaGVsOxOPKZ8o2xgIq4ro1gin8J9WRslxBEv48V AHg6EJg7dqabeKEHImrNfIMJ3WonY2XGS2h1Ohy6Szhz6wNPRZ2F1u/vP 1A3QBu5NoXaHpjPkjxGjrzrb+UpsY90lSPdwYtWuph/DRoe3KNItY9eZZ n2L4RmFBMhnAVJ25nQBYylqaidjCA0Bs3UViqaulQSAWKxeh8vdU8LlIG wBBbHfwD4L5aXf3HcOBi7gADkZr+IQnXaE9PZw8azPkKcNxHHTRBKFnDo jVR2PjadwviMfMd8BkJACq9yecxCTBD4K7HgscHq4kJ1oVJ+cHGmU4lfG w==; X-IronPort-AV: E=McAfee;i="6500,9779,10586"; a="387872549" X-IronPort-AV: E=Sophos;i="5.96,317,1665471600"; d="scan'208";a="387872549" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2023 05:24:02 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10586"; a="687927431" X-IronPort-AV: E=Sophos;i="5.96,317,1665471600"; d="scan'208";a="687927431" Received: from bachaue1-mobl1.ger.corp.intel.com (HELO box.shutemov.name) ([10.252.37.250]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2023 05:23:56 -0800 Received: by box.shutemov.name (Postfix, from userid 1000) id 53F0E109CB3; Wed, 11 Jan 2023 15:37:41 +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: [PATCHv14 08/17] x86/mm: Reduce untagged_addr() overhead until the first LAM user Date: Wed, 11 Jan 2023 15:37:27 +0300 Message-Id: <20230111123736.20025-9-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.38.2 In-Reply-To: <20230111123736.20025-1-kirill.shutemov@linux.intel.com> References: <20230111123736.20025-1-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 | 8 ++++++-- arch/x86/kernel/process_64.c | 4 ++++ 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 32c9dd052e43..f9f85d596581 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -24,6 +24,8 @@ static inline bool pagefault_disabled(void); #endif =20 #ifdef CONFIG_ADDRESS_MASKING +DECLARE_STATIC_KEY_FALSE(tagged_addr_key); + /* * Mask out tag bits from the address. * @@ -32,8 +34,10 @@ static inline bool pagefault_disabled(void); */ #define __untagged_addr(untag_mask, addr) ({ \ u64 __addr =3D (__force u64)(addr); \ - s64 sign =3D (s64)__addr >> 63; \ - __addr &=3D untag_mask | sign; \ + if (static_branch_likely(&tagged_addr_key)) { \ + s64 sign =3D (s64)__addr >> 63; \ + __addr &=3D untag_mask | sign; \ + } \ (__force __typeof__(addr))__addr; \ }) =20 diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 88aae519c8f8..1b41c60ebf6e 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -745,6 +745,9 @@ static long prctl_map_vdso(const struct vdso_image *ima= ge, unsigned long addr) =20 #ifdef CONFIG_ADDRESS_MASKING =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) @@ -781,6 +784,7 @@ 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; } #endif --=20 2.38.2