From patchwork Thu Aug 3 11:59:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Petr Tesarik X-Patchwork-Id: 130538 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:9f41:0:b0:3e4:2afc:c1 with SMTP id v1csp1103231vqx; Thu, 3 Aug 2023 05:12:26 -0700 (PDT) X-Google-Smtp-Source: APBJJlFw2wCxpZRFvcebClM+KfSk4v5I0UEG4rH+yT7kpxHLLOipuriKx2iSxOpguTs5br5Jggz5 X-Received: by 2002:a05:6870:d29d:b0:1b7:60a3:4104 with SMTP id d29-20020a056870d29d00b001b760a34104mr19535191oae.13.1691064745922; Thu, 03 Aug 2023 05:12:25 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1691064745; cv=none; d=google.com; s=arc-20160816; b=hxIzS9bqtZZxAdD7b5pEt8DZXMFpQH7ONASAI8s5VhIMDLdgvookFl5AKN4hQmsRua AIf8kxBOf14+v6sx+sXHakke3V1GEEmkR4fZ0oSxevuVpH22oHr/AGQZg0l+s0mBA0QZ LQrimPv3BvzecpwFJuDJCORYgOpaGo0acP76fS3WQ/DDZrCD/QBo/EJ4NOyZc0bk0bsL nXXvOHxL3iuD/VX6R5VZN5qMj+AyVqWfzZLucoLn2tmS8PmY125ERt/64kKwd4l1bpyL OFGMIEPSF7L81ce2Q7v4EkjPjDZ/+nuP+WswQvjspjr3ZILxOUceDB3Y9R0R7+GsZKTF vvvA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from; bh=VXfzVHpP9nCcVl65XMzE5qhFZYMVJD4SLUwfQZyls5k=; fh=ynggwOX56kCJrMV5DowWG8i5AzrNoTa+KN/4vfV+0lY=; b=SWhRb6YdtbCN1A/3aQ9jxyf26djGNKThMMIE/zQ+04WBjg9+jppM2h2xNTKWRUnKdc orePxUQYOelRa5oOkCQG5rD19kojo1ekQ4QQcP1AMBcD+3gt/xsHYARJHfjhjAuDD0ox /Z0ugI4xQLKZAlyW04jD7gtQS7wn6OltjgWe+8c9d7nDx0f0Ls5LomY+SyXt2UU2yz5/ NuoE+BOKxrIGtE+ddQefhVmo+jsxM4HyCimbCDZPxOWm48x1N7vJEDX4pWDJzug3sMs/ MXiroJ2qaDKpheQkfSpHyODW8e2hwYm+D/ieV4O9bbdfLFcItEkMwQNUYZMx1K32q9il Qirw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id j6-20020a17090a588600b002639fe8ff6bsi2939318pji.44.2023.08.03.05.11.47; Thu, 03 Aug 2023 05:12:25 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234541AbjHCMA0 (ORCPT + 99 others); Thu, 3 Aug 2023 08:00:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232363AbjHCMAX (ORCPT ); Thu, 3 Aug 2023 08:00:23 -0400 Received: from frasgout13.his.huawei.com (unknown [14.137.139.46]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 719EDE70 for ; Thu, 3 Aug 2023 05:00:20 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout13.his.huawei.com (SkyGuard) with ESMTP id 4RGnDd3ND3z9xs5v for ; Thu, 3 Aug 2023 19:48:49 +0800 (CST) Received: from A2101119013HW2.china.huawei.com (unknown [10.81.221.240]) by APP2 (Coremail) with SMTP id GxC2BwB3d++6lstkfcs3AA--.61178S2; Thu, 03 Aug 2023 13:00:01 +0100 (CET) From: Petr Tesarik To: Christoph Hellwig , Marek Szyprowski , Robin Murphy , iommu@lists.linux.dev (open list:DMA MAPPING HELPERS), linux-kernel@vger.kernel.org (open list) Cc: Roberto Sassu , petr@tesarici.cz Subject: [PATCH v1] swiotlb: optimize get_max_slots() Date: Thu, 3 Aug 2023 13:59:41 +0200 Message-Id: <20230803115941.497-1-petrtesarik@huaweicloud.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CM-TRANSID: GxC2BwB3d++6lstkfcs3AA--.61178S2 X-Coremail-Antispam: 1UD129KBjvJXoW7tw47WFWkCF4ktw45Zw1kKrg_yoW8Jw4Upa 1xJr1rGayvqF1xAa4IyFs3KFyS93srJa9xXFZ0kryfu3W5tF4FqrWxK3yqq34FqrWvkF1a va4aqw4vyr43JrDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkE14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r1j6r1xM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r1j 6r4UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v26r4j6r 4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY1x0264kExVAvwVAq 07x20xyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67 AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIY rxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14 v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j 6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JU2fO wUUUUU= X-CM-SenderInfo: hshw23xhvd2x3n6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected X-Spam-Status: No, score=-0.9 required=5.0 tests=BAYES_00,KHOP_HELO_FCRDNS, LOTS_OF_MONEY,MAY_BE_FORGED,RDNS_DYNAMIC,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773209906991782682 X-GMAIL-MSGID: 1773209906991782682 From: Petr Tesarik Use a simple logical shift and increment to calculate the number of slots taken by the DMA segment boundary. At least GCC-13 is not able to optimize the expression, producing this horrible assembly code on x86: cmpq $-1, %rcx je .L364 addq $2048, %rcx shrq $11, %rcx movq %rcx, %r13 .L331: // rest of the function here... // after function epilogue and return: .L364: movabsq $9007199254740992, %r13 jmp .L331 After the optimization, the code looks more reasonable: shrq $11, %r11 leaq 1(%r11), %rbx Signed-off-by: Petr Tesarik --- kernel/dma/swiotlb.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 2b83e3ad9dca..a95d2ea2ae18 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -577,9 +577,7 @@ static inline phys_addr_t slot_addr(phys_addr_t start, phys_addr_t idx) */ static inline unsigned long get_max_slots(unsigned long boundary_mask) { - if (boundary_mask == ~0UL) - return 1UL << (BITS_PER_LONG - IO_TLB_SHIFT); - return nr_slots(boundary_mask + 1); + return (boundary_mask >> IO_TLB_SHIFT) + 1; } static unsigned int wrap_area_index(struct io_tlb_mem *mem, unsigned int index)