From nobody Sun Feb 8 18:49:20 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 E59ACC433FE for ; Fri, 30 Sep 2022 14:48:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231699AbiI3Osw (ORCPT ); Fri, 30 Sep 2022 10:48:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231670AbiI3OsV (ORCPT ); Fri, 30 Sep 2022 10:48:21 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EBF2A12B5F0 for ; Fri, 30 Sep 2022 07:48:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1664549297; x=1696085297; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=sExrmnnOGqgb/icKqEgn6j12KzbzBwzl0nhEtIquc4M=; b=iFNAjYs8ekBUtYtoNI72xfsre1V7sbEp5jpdOwSXgwjOQlG06iE3aUF2 ULOmBifZWLoIXon3p8XcPPwdhtMytJqLtbUE3dkMV8hBtFoKo1kv6MNop ZIEeTPeD7QohUVEtsHiPP4ECB5TwW0l1uxl/Iv5kwOat12z6zzmKcTx0Y R/xgC9IC2BQoUVS2eJsow99aswOD5yXF+nu6blCV5Jy86snYyJFy3U5xv /NzwSQbKVCFcL3orA/jkf35pd6f1BB6wHZs7xJFaP9RsH4pyVk4c76yDo 0003ZYXBuk+X7mWG6Ro+iu5ywaimnj01AFcDI8+69Uh8yH5MTU4RXCKYX g==; X-IronPort-AV: E=McAfee;i="6500,9779,10486"; a="289367994" X-IronPort-AV: E=Sophos;i="5.93,358,1654585200"; d="scan'208";a="289367994" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Sep 2022 07:48:15 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10486"; a="653563756" X-IronPort-AV: E=Sophos;i="5.93,358,1654585200"; d="scan'208";a="653563756" Received: from herrerop-mobl1.ger.corp.intel.com (HELO box.shutemov.name) ([10.252.38.128]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Sep 2022 07:48:11 -0700 Received: by box.shutemov.name (Postfix, from userid 1000) id 7776A104D62; Fri, 30 Sep 2022 17:48:02 +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 , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv9 08/14] x86/mm: Reduce untagged_addr() overhead until the first LAM user Date: Fri, 30 Sep 2022 17:47:52 +0300 Message-Id: <20220930144758.30232-9-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220930144758.30232-1-kirill.shutemov@linux.intel.com> References: <20220930144758.30232-1-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 803241dfc473..fc33d6ba1090 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -22,6 +22,8 @@ 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. * @@ -30,8 +32,10 @@ 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 (mm)->context.untag_mask | sign; \ + if (static_branch_likely(&tagged_addr_key)) { \ + s64 sign =3D (s64)__addr >> 63; \ + __addr &=3D (mm)->context.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 d75252a5c7be..1730c2fcc7ab 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -742,6 +742,9 @@ 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); + static void enable_lam_func(void *mm) { struct mm_struct *loaded_mm =3D this_cpu_read(cpu_tlbstate.loaded_mm); @@ -791,6 +794,7 @@ static int prctl_enable_tagged_addr(struct mm_struct *m= m, unsigned long nr_bits) } =20 on_each_cpu_mask(mm_cpumask(mm), enable_lam_func, mm, true); + static_branch_enable(&tagged_addr_key); out: mmap_write_unlock(mm); return ret; --=20 2.35.1