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 C52ABC021A4 for ; Mon, 24 Feb 2025 18:11:25 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=dCf5LqC48vAXtMhWrnY55abItj7vuNet4puF6xMEx1o=; b=JHtDwHdI04oWHNOUAamqBGHKkG 7HsOd4t7ECrAusBwBrFOg1A3p+FherVJ3Hq09ssGeQ7nUHjZDWI2yo5W6X+eOX1xup/RLiWInHLbE mlefIMNoYCL3t0GG6cPZ7iuFKPL0S8+fs/cz5iULTK03sx3vD1ueRTCVtPsbRIbq+gZvzO5A/Ezhq /oU/RRmj43VIUkE909BMmKLCFc+eTfqXUtxmVT8X0MS/yy5+WQvmVAA/v0jF7cPvl6v95VZRGzBkW Xav+iQ4QjALtoTi5haW1Wb0BG92yhuFOBe8k8FkbgL+6+xOZJgEwDFV1x8PyzHq+Vxj0Zww/gkIPg 5AFk8ztQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tmcvF-0000000EkZb-28dK; Mon, 24 Feb 2025 18:11:17 +0000 Received: from out-170.mta0.migadu.com ([2001:41d0:1004:224b::aa]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tmctk-0000000EkK4-2vms for linux-arm-kernel@lists.infradead.org; Mon, 24 Feb 2025 18:09:46 +0000 Date: Mon, 24 Feb 2025 13:09:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rosenzweig.io; s=key1; t=1740420581; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=dCf5LqC48vAXtMhWrnY55abItj7vuNet4puF6xMEx1o=; b=KzGuzFwzVUZA8z++JLJuMsaluarmUd4hi6J59xuNydwpnDCqShcI9fvjgPi3dBPIftFarm ido4UpUcUdee+gp8FoXmS0sn9VgmaNTTncGPyStbyImI2fWI4I2CM2am7Nz+j8X606/ArX LKnawVpZCDtJwvHKWf+2yU/SRTk/lzW31vusI0gdTnhrJdLMUqkymInU2NlIsNuo/nOp6x QW/Y/n0VcEsHj2O2ZyJgeb2dVT5XzfGSLO98WznNTludm4wkUTFccBaIVb+0GOnbPz+gvw uY3xBL+6bu70T4usVXNX2GtLDLSby/XsFVtZ25S5YzgJ3f4jwttqENA5ScbLag== X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Alyssa Rosenzweig To: sven@svenpeter.dev Cc: Janne Grunau , asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Hector Martin Subject: Re: [PATCH 2/4] soc: apple: rtkit: Implement OSLog buffers properly Message-ID: References: <20250222-apple-soc-misc-v1-0-1a3af494a48a@svenpeter.dev> <20250222-apple-soc-misc-v1-2-1a3af494a48a@svenpeter.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250222-apple-soc-misc-v1-2-1a3af494a48a@svenpeter.dev> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250224_100944_873133_5ECC1B55 X-CRM114-Status: UNSURE ( 8.00 ) X-CRM114-Notice: Please train this message. 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 > + if (ep == APPLE_RTKIT_EP_OSLOG) { > + buffer->size = FIELD_GET(APPLE_RTKIT_OSLOG_SIZE, msg); > + buffer->iova = FIELD_GET(APPLE_RTKIT_OSLOG_IOVA, msg) << 12; > + } else { > + buffer->size = FIELD_GET(APPLE_RTKIT_BUFFER_REQUEST_SIZE, msg) << 12; > + buffer->iova = FIELD_GET(APPLE_RTKIT_BUFFER_REQUEST_IOVA, msg); > + } The shifts are suspiciously asymmetric. Are we really sure this is correct? My guess is that both size & iova for both oslog & buffer need to be page-aligned, so all 4 lines should be shifted, and the bit offsets should be adjusted in turn, and the lower 12-bits in oslog_size and buffer_iova are reserved. But that's just a guess. Anyway if this logic is really what we want it deserves a comment because it looks like a typo. (Likewise later in the patch)