From mboxrd@z Thu Jan 1 00:00:00 1970 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 D36FFEC8743 for ; Thu, 7 Sep 2023 17:47:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237290AbjIGRrl (ORCPT ); Thu, 7 Sep 2023 13:47:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245350AbjIGRrj (ORCPT ); Thu, 7 Sep 2023 13:47:39 -0400 Received: from mail-pf1-x430.google.com (mail-pf1-x430.google.com [IPv6:2607:f8b0:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 436ED135 for ; Thu, 7 Sep 2023 10:47:18 -0700 (PDT) Received: by mail-pf1-x430.google.com with SMTP id d2e1a72fcca58-68a3082c771so882195b3a.0 for ; Thu, 07 Sep 2023 10:47:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1694108836; x=1694713636; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=HkNuLpADsq1HxO6p8F6ChifHRIKFqFA3PCMXwO6LXU4=; b=Zo8Wmflu33mX0ydth7qvEnXJj4kKAnZSaotrw/tNJKXjepX96JLQDQyqGluhQTIY39 mj8iVkga9+xvmS2xM/5m5L8hBuquGzXhu8pH8YnRdtW4peO9z3zD0/19pej4i3qbmPrM L+u0TN7HUhjIWJqzMKC04n4yUTfddOwQe0qEP1koL64hBFzQQVSMkmgdWRUGGFQcqaRM n2kZk724vYAs9R+d0i1Ukc8yHp+jpIAP5q/M8tGIYmx3MwxkW3aU/Y1VVrtfAhimtMYw O/0K94KTT8RelaDKSTFbkV5NNeXA6SiXpcb5y03f+Y4cAsChnXQI22rwvMEIREtLmdvC 4ANA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694108836; x=1694713636; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=HkNuLpADsq1HxO6p8F6ChifHRIKFqFA3PCMXwO6LXU4=; b=XT9Lu4Pv/eCzlouAl9QaUzdNEXisT0kenWFdhhbk7e8bOCHil7rdV9oYcgAa6TlvnW 20Sz97gaqphA73P3nODvDA8rbZRP/vi0CMpR+SQ4jrspbbE+uJrIHm7wxk548oXiK2rG msk2ElUCdNd+oCfq6cHFeQ8ikLV/UdsnM+8fgl+5xsrfijdBls/5Ew9iKfTNhc1yDoJl 2Jbuu98LgOM5oSpIxGMaqXGviJ95pclvcY8P7gdxWnvMIzufHHM8z+ouwOYofBCIdTAS 5tMllQXrpVSfi7KK695yzG9R8/xFFaseGdgInTGVT9QaRvCk1e0MgS2dVwM3l0jW5Qp/ uC3Q== X-Gm-Message-State: AOJu0YyqCHcrneCxjx0HSIpt3208CFF+p4owNPRdxnSrSxxjAqsdWPS4 dByYXUKRf3Rv81f3zqJebsrr+Q== X-Google-Smtp-Source: AGHT+IHtGyzHQWdfOQOsK2cxB6aenF+V0LcJKTzFVrUzD4aaSH/IBNPbrk+n11AmEY9FSvaZ0QhLeA== X-Received: by 2002:a05:6a00:2995:b0:68e:38cf:9de8 with SMTP id cj21-20020a056a00299500b0068e38cf9de8mr3964462pfb.9.1694108836223; Thu, 07 Sep 2023 10:47:16 -0700 (PDT) Received: from ghost ([2601:647:5700:6860:84f6:5055:9180:822]) by smtp.gmail.com with ESMTPSA id z12-20020aa791cc000000b0068844ee18dfsm11025pfa.83.2023.09.07.10.47.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Sep 2023 10:47:15 -0700 (PDT) Date: Thu, 7 Sep 2023 10:47:13 -0700 From: Charlie Jenkins To: Conor Dooley Cc: Palmer Dabbelt , Samuel Holland , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Paul Walmsley , Albert Ou Subject: Re: [PATCH v2 2/5] riscv: Add checksum library Message-ID: References: <20230905-optimize_checksum-v2-0-ccd658db743b@rivosinc.com> <20230905-optimize_checksum-v2-2-ccd658db743b@rivosinc.com> <20230907-9d5d2e7ef2a20edd75514470@fedora> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230907-9d5d2e7ef2a20edd75514470@fedora> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 07, 2023 at 10:52:35AM +0100, Conor Dooley wrote: > On Tue, Sep 05, 2023 at 09:46:51PM -0700, Charlie Jenkins wrote: > > > +#ifdef CONFIG_RISCV_ISA_ZBB > > + if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) { > > + /* > > + * Zbb is likely available when the kernel is compiled with Zbb > > + * support, so nop when Zbb is available and jump when Zbb is > > + * not available. > > + */ > > + asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, > > + RISCV_ISA_EXT_ZBB, 1) > > + : > > + : > > + : > > + : no_zbb); > > + } else { > > + if (!__riscv_isa_extension_available(NULL, RISCV_ISA_EXT_ZBB)) > > + goto no_zbb; > > + } > > Again, do these constructs have an appreciable benefit over doing > if (!riscv_has_extension_likely() > goto no_zbb; > > ? > > That encaspulates the fallback to a non-alternative mechanism for you, > in case you had not noticed. I got caught up in the other patch where I did not want to fall back, so then in this patch I forgot I could use riscv_has_extension_likely. I will make the change. - Charlie