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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 AA2FE1062896 for ; Wed, 11 Mar 2026 13:05:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1018D10E8E6; Wed, 11 Mar 2026 13:05:57 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="EvkrumX3"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9330310E8E6; Wed, 11 Mar 2026 13:05:55 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 549D6440AA; Wed, 11 Mar 2026 13:05:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5913C19425; Wed, 11 Mar 2026 13:05:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773234355; bh=nbZBUsdJcvcRYXPC15YGXFPTjlIlWJ4Gu6T6ZsV2KtY=; h=Date:Subject:Cc:To:From:References:In-Reply-To:From; b=EvkrumX33ovdE3XY7rAl0LGIpmzKFuCtSoK0XC5sVrCq4wBOqxNrlndO6w4HOHGO8 jLWVOwwUXQWzAOnsw9Yt1RLYHA5IDzWMh+XHqnPu5u4CK0XoWNA9UWNjOc0QfnNyYQ YRukM9Bo8TdJyktArOzBJGJqhPdquElra7adPC3ikoYJn28YKwy4MeoI0Oq1YeMhVj eHWodu0AL8oBTCYm24/VU2jD9wgz99jcS6CUCHRYa7Bq3VHTtCczcnYM25CEMYfFGf 6ptXM6KcayHRoi+OCyzuU/ThLqoMNZwGGpS4Oeq5HiYsxH37sFdObnEfdIvzLEHVSx PES6/OYo8y29A== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 11 Mar 2026 14:05:52 +0100 Message-Id: Subject: Re: [PATCH] gpu: nova-core: gsp: fix UB in DmaGspMem pointer accessors Cc: , , , , , To: "Gary Guo" From: "Danilo Krummrich" References: <20260309225408.27714-1-dakr@kernel.org> In-Reply-To: X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Wed Mar 11, 2026 at 1:59 PM CET, Gary Guo wrote: > On Tue Mar 10, 2026 at 10:58 AM GMT, Danilo Krummrich wrote: >> On Tue Mar 10, 2026 at 3:01 AM CET, Gary Guo wrote: >>>> +// TODO: Revert to private once `IoView` projections replace the `gsp= _mem` module. >>>> +pub(in crate::gsp) struct Msgq { >>> >>> These could all be `(in super)`? >> >> Yes, or just pub(super). However, that's not the case for the functions = in the >> gsp_mem module, they could be pub(in super::super) though. But I think I= prefer >> pub(in crate::gsp) for those. >> >>>> + pub(in crate::gsp) fn gsp_write_ptr(qs: &CoherentAllocation) -> u32 { >>>> + // PANIC: A `dma::CoherentAllocation` always contains at leas= t one element. >>>> + || -> Result { Ok(dma_read!(qs, [0]?.gspq.tx.0.writePtr)= % MSGQ_NUM_PAGES) }().unwrap() >>> >>> I wonder if I should add a panicking variant of index projection for th= is case. >>> Perhaps of syntax `[index]!`. >>> >>> We could also make the existing `[index]` becoming a panicking one inst= ead of >>> `build_error!` one. It is more consistent with Rust index operator that= way. >> >> I thought the same, as something like this `[n]?.ptes[i]` looks a bit od= d. >> >> However, I think we ideally want both variants (I like your `[i]!` propo= sal >> above), since generally users should have the choice (as they also have = with a >> slice through get()). For instance, the index could come from userspace.= Sure, >> you can always validate the index in advance, but having a fallible vari= ant is a >> bit nicer. > > I'm not proposing removal of the fallible variant, just that we can make = the > infallible one use panicking instead of `build_error!`. SGTM.