From patchwork Thu May 6 13:27:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 1474971 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4FbZC30qBkz9sWk for ; Thu, 6 May 2021 23:27:59 +1000 (AEST) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4FbZC30QV6z30Cm for ; Thu, 6 May 2021 23:27:59 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.235.10; helo=pegase2.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FbZBg2Mwjz300x for ; Thu, 6 May 2021 23:27:34 +1000 (AEST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4FbZBW72S8z9sVL; Thu, 6 May 2021 15:27:31 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id FUbtJ3WmSgka; Thu, 6 May 2021 15:27:31 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4FbZBW68cWz9sV0; Thu, 6 May 2021 15:27:31 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id B31AF8B801; Thu, 6 May 2021 15:27:31 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id BIwZu-HeAFJI; Thu, 6 May 2021 15:27:31 +0200 (CEST) Received: from po15610vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 6C6798B800; Thu, 6 May 2021 15:27:31 +0200 (CEST) Received: by po15610vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 455096489F; Thu, 6 May 2021 13:27:31 +0000 (UTC) Message-Id: <848f18d213b8341939add7302dc4ef80cc7a12e3.1620307636.git.christophe.leroy@csgroup.eu> From: Christophe Leroy Subject: [PATCH] powerpc/32s: Speed up likely path of kuap_update_sr() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Date: Thu, 6 May 2021 13:27:31 +0000 (UTC) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" In most cases, kuap_update_sr() will update a single segment register. We know that first update will always be done, if there is no segment register to update at all, kuap_update_sr() is not called. Avoid recurring calculations and tests in that case. Signed-off-by: Christophe Leroy --- arch/powerpc/include/asm/book3s/32/kup.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index 1670dfe9d4f1..c1f7c2e625a6 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -15,11 +15,13 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end) { addr &= 0xf0000000; /* align addr to start of segment */ barrier(); /* make sure thread.kuap is updated before playing with SRs */ - while (addr < end) { + for (;;) { mtsr(sr, addr); + addr += 0x10000000; /* address of next segment */ + if (addr >= end) + break; sr += 0x111; /* next VSID */ sr &= 0xf0ffffff; /* clear VSID overflow */ - addr += 0x10000000; /* address of next segment */ } isync(); /* Context sync required after mtsr() */ }