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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92B72C1B0D9 for ; Sat, 5 Dec 2020 18:42:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DD1222EBF for ; Sat, 5 Dec 2020 18:42:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727304AbgLESTT (ORCPT ); Sat, 5 Dec 2020 13:19:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727065AbgLERic (ORCPT ); Sat, 5 Dec 2020 12:38:32 -0500 Received: from mail-qk1-x741.google.com (mail-qk1-x741.google.com [IPv6:2607:f8b0:4864:20::741]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 142C1C09425D; Sat, 5 Dec 2020 08:54:10 -0800 (PST) Received: by mail-qk1-x741.google.com with SMTP id x25so8614230qkj.3; Sat, 05 Dec 2020 08:54:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=oIRoSEGJLf8joA0+34Z8WBxAWHJSo0r9QDagd8ox+Nc=; b=BVpGu4oj+2gagBMnBu5fD2tvH6kcIWlE4peCRgnJzfVLK+9RxA5P9FS6GqMqfuZv78 sWDNKqVJqPeWWQCauATjKT4q0ZlHM0PYVyO0JFXfDwk9hLCoB+QOG9XKncu2kGfEHaFf 848aUPFnkqR4zzUq7Rhm4Jk9SGJCGlrYnbHBXWe+065eWwWe7zjR5vzmzixGDP9GynHK 8TokbuFMkyGkCxsrKq927pwBGqPVTAa/5iKLCqO98kYHLfRdNh+S9t1RwZNcNwqKsyum dxfpTDWHYfyxTyHpkTnkNpMfP+WCBl3DDFrB4C8bRaZDPO2MLIIwnawu1ygxoOT85CsZ 2LiA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=oIRoSEGJLf8joA0+34Z8WBxAWHJSo0r9QDagd8ox+Nc=; b=KL4j8xZxoNi4qBpjduaP+aZtZU+ccn5jCIuKSB6e0DUhf49vwcy6UGduF8cU8sOfKq BnS99kYBKzSRsi+UaBGl7rH4OQEADZBp+qkvRTRgmZYvZjL+GTuSijD5dvfFVw/bznLV cHopqXCh/4E8hQf+Wxv0dWDd30r+YV96Uhdvk1sTjHn7FgXX7NKDUDgQ2iNM0AHvO43J nNW7d0Sc8VUh6C3YFsNvuIHax6+9ddZ0HEaN1cAZKuFL9OgA/VnRf5aLcjfBef4CC4HE UTTwTjGYs0PqKTZ9ZlvK566A9fVHUErgBIvzMTVjXZ5virriAy5CTBazTiSFRoHORch1 yyhA== X-Gm-Message-State: AOAM530aItOUNCIZ+fBGikLHtPwSPN/avWXbDgDhLGldR/Z1OnYfGNd2 3aIVrnZKe4WHcKKh3uXvwKVcqj3zVU/rlw== X-Google-Smtp-Source: ABdhPJziRERFUWIPA3cN72AJFivk2FJHGpMa80KMnN1GBZqAqPU3SLoRnHLbIkQ2NQ3W7XSTrN+r4A== X-Received: by 2002:a37:2d05:: with SMTP id t5mr1146929qkh.187.1607187249235; Sat, 05 Dec 2020 08:54:09 -0800 (PST) Received: from localhost ([12.221.2.200]) by smtp.gmail.com with ESMTPSA id c138sm9114777qke.95.2020.12.05.08.54.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Dec 2020 08:54:08 -0800 (PST) From: Yury Norov To: Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Cc: Yury Norov Subject: [PATCH] arm64: enable GENERIC_FIND_FIRST_BIT Date: Sat, 5 Dec 2020 08:54:06 -0800 Message-Id: <20201205165406.108990-1-yury.norov@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org ARM64 doesn't implement find_first_{zero}_bit in arch code and doesn't enable it in config. It leads to using find_next_bit() which is less efficient: 0000000000000000 : 0: aa0003e4 mov x4, x0 4: aa0103e0 mov x0, x1 8: b4000181 cbz x1, 38 c: f9400083 ldr x3, [x4] 10: d2800802 mov x2, #0x40 // #64 14: 91002084 add x4, x4, #0x8 18: b40000c3 cbz x3, 30 1c: 14000008 b 3c 20: f8408483 ldr x3, [x4], #8 24: 91010045 add x5, x2, #0x40 28: b50000c3 cbnz x3, 40 2c: aa0503e2 mov x2, x5 30: eb02001f cmp x0, x2 34: 54ffff68 b.hi 20 // b.pmore 38: d65f03c0 ret 3c: d2800002 mov x2, #0x0 // #0 40: dac00063 rbit x3, x3 44: dac01063 clz x3, x3 48: 8b020062 add x2, x3, x2 4c: eb02001f cmp x0, x2 50: 9a829000 csel x0, x0, x2, ls // ls = plast 54: d65f03c0 ret ... 0000000000000118 <_find_next_bit.constprop.1>: 118: eb02007f cmp x3, x2 11c: 540002e2 b.cs 178 <_find_next_bit.constprop.1+0x60> // b.hs, b.nlast 120: d346fc66 lsr x6, x3, #6 124: f8667805 ldr x5, [x0, x6, lsl #3] 128: b4000061 cbz x1, 134 <_find_next_bit.constprop.1+0x1c> 12c: f8667826 ldr x6, [x1, x6, lsl #3] 130: 8a0600a5 and x5, x5, x6 134: ca0400a6 eor x6, x5, x4 138: 92800005 mov x5, #0xffffffffffffffff // #-1 13c: 9ac320a5 lsl x5, x5, x3 140: 927ae463 and x3, x3, #0xffffffffffffffc0 144: ea0600a5 ands x5, x5, x6 148: 54000120 b.eq 16c <_find_next_bit.constprop.1+0x54> // b.none 14c: 1400000e b 184 <_find_next_bit.constprop.1+0x6c> 150: d346fc66 lsr x6, x3, #6 154: f8667805 ldr x5, [x0, x6, lsl #3] 158: b4000061 cbz x1, 164 <_find_next_bit.constprop.1+0x4c> 15c: f8667826 ldr x6, [x1, x6, lsl #3] 160: 8a0600a5 and x5, x5, x6 164: eb05009f cmp x4, x5 168: 540000c1 b.ne 180 <_find_next_bit.constprop.1+0x68> // b.any 16c: 91010063 add x3, x3, #0x40 170: eb03005f cmp x2, x3 174: 54fffee8 b.hi 150 <_find_next_bit.constprop.1+0x38> // b.pmore 178: aa0203e0 mov x0, x2 17c: d65f03c0 ret 180: ca050085 eor x5, x4, x5 184: dac000a5 rbit x5, x5 188: dac010a5 clz x5, x5 18c: 8b0300a3 add x3, x5, x3 190: eb03005f cmp x2, x3 194: 9a839042 csel x2, x2, x3, ls // ls = plast 198: aa0203e0 mov x0, x2 19c: d65f03c0 ret ... 0000000000000238 : 238: a9bf7bfd stp x29, x30, [sp, #-16]! 23c: aa0203e3 mov x3, x2 240: d2800004 mov x4, #0x0 // #0 244: aa0103e2 mov x2, x1 248: 910003fd mov x29, sp 24c: d2800001 mov x1, #0x0 // #0 250: 97ffffb2 bl 118 <_find_next_bit.constprop.1> 254: a8c17bfd ldp x29, x30, [sp], #16 258: d65f03c0 ret Enabling this functions would also benefit for_each_{set,clear}_bit(). Would it make sense to enable this config for all such architectures by default? Signed-off-by: Yury Norov --- arch/arm64/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1515f6f153a0..2b90ef1f548e 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -106,6 +106,7 @@ config ARM64 select GENERIC_CPU_AUTOPROBE select GENERIC_CPU_VULNERABILITIES select GENERIC_EARLY_IOREMAP + select GENERIC_FIND_FIRST_BIT select GENERIC_IDLE_POLL_SETUP select GENERIC_IRQ_IPI select GENERIC_IRQ_MULTI_HANDLER -- 2.25.1