From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C910190485; Mon, 7 Apr 2025 20:39:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744058400; cv=none; b=h4sblHJV5/fzlLFJbIdP7eK7QBZcRwinzco23GLJomHDVoy867zJy4sIVpSbCp7Gti44J4yz6toJlHAIrJRoOPJVVJtvKAi5ocXdx3EY7xSWWakbQ+lf4dXa7t1JOtmTPbYboKhPgukxMOXUMgE1ZueopdnIro067mhAnNxjwUc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744058400; c=relaxed/simple; bh=8HrL1EgPSyklT7FSW/bGqrEJaT6sICo4hJtgxDc0L7o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NROUXWLJuk8yGAfJhTr0kDniTGaKnFjbDjV97oe5eUfO0xIV4TYpnfW3jptiaJbx1fk5/qmDW85YXqnAiMUuHnOAVGsczktY3wQ4VEwxcLGEL87TCVRjLEO4/fCLTVi9SGCn8FnW9U5xNoNMtOm3x8wfrZK/3zHqePKmnXXGFrk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mpc9xriB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mpc9xriB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76592C4CEDD; Mon, 7 Apr 2025 20:39:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744058399; bh=8HrL1EgPSyklT7FSW/bGqrEJaT6sICo4hJtgxDc0L7o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mpc9xriBNIdKRA/FdQOVqQUjDpYiskXXHaB8SSN3PVPbEx0d7G72cuRTQV0mYbOkM LCECEwRHcHzj7qetGGF3Z+TfclcqxSbxYYj5YTR0Gv/ZPW4DyTUkOk/e1ojZ5UFsOD oCoqwEe9MmWorEXYlfOygne4KqgZhSU9CSOOJ/rTKm8/a31dXkLQcApADxdW7/1X9j 0gqnwikX3XIEqgaoV/qLW0InHG1yeoXFuyzVjVz1pUyR0rZ4glt61wPEinEj7gn1Oa 7v6LbNQw97DMWVdhyCe/+V9vOBNv2iHpheY2Ozh14XTZUfSx6F3XJ3wSSImcfkxEuz MIjjTi1sxf/OA== Date: Mon, 7 Apr 2025 13:39:56 -0700 From: Kees Cook To: "Gustavo A. R. Silva" Cc: "Gustavo A. R. Silva" , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH][next] drm/nouveau: chan: Avoid -Wflex-array-member-not-at-end warnings Message-ID: <202504071336.0C708FCAB8@keescook> References: <202504071227.E8484EB@keescook> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Apr 07, 2025 at 01:57:48PM -0600, Gustavo A. R. Silva wrote: > > > On 07/04/25 13:50, Kees Cook wrote: > > On Thu, Apr 03, 2025 at 10:45:18AM -0600, Gustavo A. R. Silva wrote: > > > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > > > getting ready to enable it, globally. > > > > > > Use the `DEFINE_RAW_FLEX()` helper for a few on-stack definitions > > > of a flexible structure where the size of the flexible-array member > > > is known at compile-time, and refactor the rest of the code, > > > accordingly. > > > > > > So, with these changes, fix the following warnings: > > > > > > drivers/gpu/drm/nouveau/nouveau_chan.c:274:37: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > > drivers/gpu/drm/nouveau/nouveau_chan.c:371:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > > drivers/gpu/drm/nouveau/nouveau_chan.c:524:42: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > > > > > Signed-off-by: Gustavo A. R. Silva > > > --- > > > drivers/gpu/drm/nouveau/nouveau_chan.c | 115 ++++++++++++------------- > > > 1 file changed, 56 insertions(+), 59 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c b/drivers/gpu/drm/nouveau/nouveau_chan.c > > > index cd659b9fd1d9..a7e70517b7cd 100644 > > > --- a/drivers/gpu/drm/nouveau/nouveau_chan.c > > > +++ b/drivers/gpu/drm/nouveau/nouveau_chan.c > > > @@ -270,10 +270,7 @@ nouveau_channel_ctor(struct nouveau_cli *cli, bool priv, u64 runm, > > > { NV03_CHANNEL_DMA , 0 }, > > > {} > > > }; > > > - struct { > > > - struct nvif_chan_v0 chan; > > > - char name[TASK_COMM_LEN+16]; > > > - } args; > > > + DEFINE_RAW_FLEX(struct nvif_chan_v0, args, name, TASK_COMM_LEN + 16); > > > struct nvif_device *device = &cli->device; > > > struct nouveau_channel *chan; > > > const u64 plength = 0x10000; > > > @@ -298,28 +295,28 @@ nouveau_channel_ctor(struct nouveau_cli *cli, bool priv, u64 runm, > > > return ret; > > > /* create channel object */ > > > - args.chan.version = 0; > > > - args.chan.namelen = sizeof(args.name); > > > - args.chan.runlist = __ffs64(runm); > > > - args.chan.runq = 0; > > > - args.chan.priv = priv; > > > - args.chan.devm = BIT(0); > > > + args->version = 0; > > > + args->namelen = __struct_size(args) - sizeof(*args); > > > > Does __struct_size(args->name) work here (and later)? > > Why not? Uhm, I'm genuinely curious. I *think* it will work, but because it's within the struct, not outside of it, I'm unclear if it'll DTRT for finding the size (since __builtin_object_size() can be touchy). > I mean, this should be equivalent to `TASK_COMM_LEN+16`, I could > use the latter if people prefer it (see my comments below). Right, it should be the same. I think __struct_size(args->name) would be much more readable ... if it works. :) > > > > > > + args->runlist = __ffs64(runm); > > > + args->runq = 0; > > > + args->priv = priv; > > > + args->devm = BIT(0); > > > if (hosts[cid].oclass < NV50_CHANNEL_GPFIFO) { > > > - args.chan.vmm = 0; > > > - args.chan.ctxdma = nvif_handle(&chan->push.ctxdma); > > > - args.chan.offset = chan->push.addr; > > > - args.chan.length = 0; > > > + args->vmm = 0; > > > + args->ctxdma = nvif_handle(&chan->push.ctxdma); > > > + args->offset = chan->push.addr; > > > + args->length = 0; > > > } else { > > > - args.chan.vmm = nvif_handle(&chan->vmm->vmm.object); > > > + args->vmm = nvif_handle(&chan->vmm->vmm.object); > > > if (hosts[cid].oclass < FERMI_CHANNEL_GPFIFO) > > > - args.chan.ctxdma = nvif_handle(&chan->push.ctxdma); > > > + args->ctxdma = nvif_handle(&chan->push.ctxdma); > > > else > > > - args.chan.ctxdma = 0; > > > - args.chan.offset = ioffset + chan->push.addr; > > > - args.chan.length = ilength; > > > + args->ctxdma = 0; > > > + args->offset = ioffset + chan->push.addr; > > > + args->length = ilength; > > > } > > > - args.chan.huserd = 0; > > > - args.chan.ouserd = 0; > > > + args->huserd = 0; > > > + args->ouserd = 0; > > > /* allocate userd */ > > > if (hosts[cid].oclass >= VOLTA_CHANNEL_GPFIFO_A) { > > > @@ -329,27 +326,28 @@ nouveau_channel_ctor(struct nouveau_cli *cli, bool priv, u64 runm, > > > if (ret) > > > return ret; > > > - args.chan.huserd = nvif_handle(&chan->mem_userd.object); > > > - args.chan.ouserd = 0; > > > + args->huserd = nvif_handle(&chan->mem_userd.object); > > > + args->ouserd = 0; > > > chan->userd = &chan->mem_userd.object; > > > } else { > > > chan->userd = &chan->user; > > > } > > > - snprintf(args.name, sizeof(args.name), "%s[%d]", current->comm, task_pid_nr(current)); > > > + snprintf(args->name, __struct_size(args) - sizeof(*args), "%s[%d]", > > > + current->comm, task_pid_nr(current)); > > > ret = nvif_object_ctor(&device->object, "abi16ChanUser", 0, hosts[cid].oclass, > > > - &args, sizeof(args), &chan->user); > > > + args, __struct_size(args), &chan->user); > > > if (ret) { > > > nouveau_channel_del(pchan); > > > return ret; > > > } > > > - chan->runlist = args.chan.runlist; > > > - chan->chid = args.chan.chid; > > > - chan->inst = args.chan.inst; > > > - chan->token = args.chan.token; > > > + chan->runlist = args->runlist; > > > + chan->chid = args->chid; > > > + chan->inst = args->inst; > > > + chan->token = args->token; > > > return 0; > > > } > > > @@ -367,17 +365,17 @@ nouveau_channel_init(struct nouveau_channel *chan, u32 vram, u32 gart) > > > return ret; > > > if (chan->user.oclass >= FERMI_CHANNEL_GPFIFO) { > > > - struct { > > > - struct nvif_event_v0 base; > > > - struct nvif_chan_event_v0 host; > > > - } args; > > > + DEFINE_RAW_FLEX(struct nvif_event_v0, args, data, > > > + sizeof(struct nvif_chan_event_v0)); > > > + struct nvif_chan_event_v0 *host = > > > + (struct nvif_chan_event_v0 *)args->data; > > > - args.host.version = 0; > > > - args.host.type = NVIF_CHAN_EVENT_V0_KILLED; > > > + host->version = 0; > > > + host->type = NVIF_CHAN_EVENT_V0_KILLED; > > > ret = nvif_event_ctor(&chan->user, "abi16ChanKilled", chan->chid, > > > nouveau_channel_killed, false, > > > - &args.base, sizeof(args), &chan->kill); > > > + args, __struct_size(args), &chan->kill); > > > if (ret == 0) > > > ret = nvif_event_allow(&chan->kill); > > > if (ret) { > > > @@ -520,46 +518,45 @@ nouveau_channels_fini(struct nouveau_drm *drm) > > > int > > > nouveau_channels_init(struct nouveau_drm *drm) > > > { > > > - struct { > > > - struct nv_device_info_v1 m; > > > - struct { > > > - struct nv_device_info_v1_data channels; > > > - struct nv_device_info_v1_data runlists; > > > - } v; > > > - } args = { > > > - .m.version = 1, > > > - .m.count = sizeof(args.v) / sizeof(args.v.channels), > > > > sizeof(args.v) == sizeof(struct nv_device_info_v1_data) * 2 > > > > and sizeof(args.v.channels) == sizeof(struct nv_device_info_v1_data). > > > > Isn't this just "2"? i.e. isn't struct nv_device_info_v1::count the > > counted_by for struct nv_device_info_v1::data? > > Yes, it's just `2`. However, I didn't want to explicitly use the magic > number, in case people don't like it, as in other similar patches (in > other subsystems). > > But, yeah, it's `2`. :) Okay. So if "count" is set up as a counted_by, the assignment will happen automatically (in DEFINE_FLEX -- no longer "RAW"). > > Thanks > -- > Gustavo > > > > > > - .v.channels.mthd = NV_DEVICE_HOST_CHANNELS, > > > - .v.runlists.mthd = NV_DEVICE_HOST_RUNLISTS, > > > - }; > > > + DEFINE_RAW_FLEX(struct nv_device_info_v1, args, data, 2); > > > + struct nv_device_info_v1_data *channels = &args->data[0]; > > > + struct nv_device_info_v1_data *runlists = &args->data[1]; > > > struct nvif_object *device = &drm->client.device.object; > > > int ret, i; > > > - ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, &args, sizeof(args)); > > > + args->version = 1; > > > + args->count = (__struct_size(args) - sizeof(*args)) / > > > + sizeof(*args->data); > > > + channels->mthd = NV_DEVICE_HOST_CHANNELS; > > > + runlists->mthd = NV_DEVICE_HOST_RUNLISTS; > > > + > > > + ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, args, > > > + __struct_size(args)); > > > if (ret || > > > - args.v.runlists.mthd == NV_DEVICE_INFO_INVALID || !args.v.runlists.data || > > > - args.v.channels.mthd == NV_DEVICE_INFO_INVALID) > > > + runlists->mthd == NV_DEVICE_INFO_INVALID || !runlists->data || > > > + channels->mthd == NV_DEVICE_INFO_INVALID) > > > return -ENODEV; > > > - drm->chan_nr = drm->chan_total = args.v.channels.data; > > > - drm->runl_nr = fls64(args.v.runlists.data); > > > + drm->chan_nr = drm->chan_total = channels->data; > > > + drm->runl_nr = fls64(runlists->data); > > > drm->runl = kcalloc(drm->runl_nr, sizeof(*drm->runl), GFP_KERNEL); > > > if (!drm->runl) > > > return -ENOMEM; > > > if (drm->chan_nr == 0) { > > > for (i = 0; i < drm->runl_nr; i++) { > > > - if (!(args.v.runlists.data & BIT(i))) > > > + if (!(runlists->data & BIT(i))) > > > continue; > > > - args.v.channels.mthd = NV_DEVICE_HOST_RUNLIST_CHANNELS; > > > - args.v.channels.data = i; > > > + channels->mthd = NV_DEVICE_HOST_RUNLIST_CHANNELS; > > > + channels->data = i; > > > - ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, &args, sizeof(args)); > > > - if (ret || args.v.channels.mthd == NV_DEVICE_INFO_INVALID) > > > + ret = nvif_object_mthd(device, NV_DEVICE_V0_INFO, args, > > > + __struct_size(args)); > > > + if (ret || channels->mthd == NV_DEVICE_INFO_INVALID) > > > return -ENODEV; > > > - drm->runl[i].chan_nr = args.v.channels.data; > > > + drm->runl[i].chan_nr = channels->data; > > > drm->runl[i].chan_id_base = drm->chan_total; > > > drm->runl[i].context_base = dma_fence_context_alloc(drm->runl[i].chan_nr); > > > > Otherwise looks good. > > > > -Kees > > > -- Kees Cook