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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A2AB9CCF9F8 for ; Fri, 31 Oct 2025 13:49:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:CC:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=kUCtGCFwRvUEG4Bh7Y4FA/+ZjBJuHT2lo6zXAMV1QvY=; b=W+q4iH6zmELrCwP6jXLtBYedi2 PgxvGJKYiJctMcF7i0G7Hl6YKMZuDAe/L2mw8I5DoBGWcNxTqOGIHHdYTS4H9lyN8Xry3rRj4aev4 06qF8mu5kZ8okHFFE9Y8a7FJQm69Sw6Lguxcx+rmyb6ChJhlOrMBkRwIWSlaOl98jpMtVgrKZOqxz pyy3azCOgzkZtEnT5KmG/UbMGt19qFp4MwC10c5hOZODvrvdpNy5S3ZIu+7MuLUwvlcz+AuV2SMJb htRC+yE211Ox3KdjSwMAErb9FCpeaLzsQuXZVW8MOJ6PLBRDErgBq11YuOMYpfQxiXOR0e2RFSybz gdJb40Fg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vEpVG-00000006Aqx-1fmb; Fri, 31 Oct 2025 13:49:18 +0000 Received: from frasgout.his.huawei.com ([185.176.79.56]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vEpVD-00000006Aq9-2y7j for linux-arm-kernel@lists.infradead.org; Fri, 31 Oct 2025 13:49:17 +0000 Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4cyj0s3JBjz6L4ws; Fri, 31 Oct 2025 21:45:33 +0800 (CST) Received: from dubpeml100005.china.huawei.com (unknown [7.214.146.113]) by mail.maildlp.com (Postfix) with ESMTPS id D81631402E9; Fri, 31 Oct 2025 21:49:11 +0800 (CST) Received: from localhost (10.203.177.15) by dubpeml100005.china.huawei.com (7.214.146.113) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 31 Oct 2025 13:49:11 +0000 Date: Fri, 31 Oct 2025 13:49:09 +0000 From: Jonathan Cameron To: Ard Biesheuvel CC: , , , , , Ard Biesheuvel Subject: Re: [PATCH v4 08/21] lib/crc: Switch ARM and arm64 to 'ksimd' scoped guard API Message-ID: <20251031134909.00006bf3@huawei.com> In-Reply-To: <20251031103858.529530-31-ardb+git@google.com> References: <20251031103858.529530-23-ardb+git@google.com> <20251031103858.529530-31-ardb+git@google.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.203.177.15] X-ClientProxiedBy: lhrpeml100011.china.huawei.com (7.191.174.247) To dubpeml100005.china.huawei.com (7.214.146.113) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251031_064915_931950_BCEC4C7B X-CRM114-Status: GOOD ( 16.74 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 31 Oct 2025 11:39:07 +0100 Ard Biesheuvel wrote: > From: Ard Biesheuvel > > Before modifying the prototypes of kernel_neon_begin() and > kernel_neon_end() to accommodate kernel mode FP/SIMD state buffers > allocated on the stack, move arm64 to the new 'ksimd' scoped guard API, > which encapsulates the calls to those functions. > > For symmetry, do the same for 32-bit ARM too. > > Reviewed-by: Eric Biggers > Signed-off-by: Ard Biesheuvel > --- > lib/crc/arm/crc-t10dif.h | 16 +++++----------- > lib/crc/arm/crc32.h | 11 ++++------- > lib/crc/arm64/crc-t10dif.h | 16 +++++----------- > lib/crc/arm64/crc32.h | 16 ++++++---------- > 4 files changed, 20 insertions(+), 39 deletions(-) > > diff --git a/lib/crc/arm/crc-t10dif.h b/lib/crc/arm/crc-t10dif.h > index 63441de5e3f1..aaeeab0defb5 100644 > --- a/lib/crc/arm/crc-t10dif.h > +++ b/lib/crc/arm/crc-t10dif.h > static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon); > @@ -20,21 +19,16 @@ asmlinkage void crc_t10dif_pmull8(u16 init_crc, const u8 *buf, size_t len, > static inline u16 crc_t10dif_arch(u16 crc, const u8 *data, size_t length) > { > if (length >= CRC_T10DIF_PMULL_CHUNK_SIZE) { > - if (static_branch_likely(&have_pmull)) { > - if (likely(may_use_simd())) { > - kernel_neon_begin(); > - crc = crc_t10dif_pmull64(crc, data, length); > - kernel_neon_end(); > - return crc; > - } > + if (static_branch_likely(&have_pmull) && likely(may_use_simd())) { > + scoped_ksimd() > + return crc_t10dif_pmull64(crc, data, length); > } else if (length > CRC_T10DIF_PMULL_CHUNK_SIZE && > static_branch_likely(&have_neon) && > likely(may_use_simd())) { I briefly thought this was a functional change but it's not because of may_use_simd() being something that isn't going to change between the two evaluations. Would it hurt at all to pull that up to be if (length >= CRC_T10DIF_PMULL_CHUNK_SIZE && likely(may_use_simd())) { if (static_branch_likely(&have_pmull)) { scoped_ksimd() return crc_t10dif_pmull64(crc, data, length); } else if (length > CRC_T10DIF_PMULL_CHUNK_SIZE && static_branch_likely(&have_neon)) { ... ?