From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v2 1/1] remoteproc: correct rproc_free_vring() to avoid invalid kernel paging References: <1530863212-16584-1-git-send-email-loic.pallardy@st.com> <8e943f4d2a1b4e10a8a0756c737d53a8@SFHDAG7NODE2.st.com> From: Suman Anna Message-ID: <56aeb569-cd4d-3769-fdad-ee3d4dbdc19b@ti.com> Date: Thu, 26 Jul 2018 18:51:47 -0500 MIME-Version: 1.0 In-Reply-To: <8e943f4d2a1b4e10a8a0756c737d53a8@SFHDAG7NODE2.st.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit To: Loic PALLARDY , "bjorn.andersson@linaro.org" , "ohad@wizery.com" Cc: "linux-remoteproc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Arnaud POULIQUEN , "benjamin.gaignard@linaro.org" List-ID: Hi Loic, On 07/26/2018 02:48 AM, Loic PALLARDY wrote: > Hi Suman, >> >> Hi Loic, >> >> On 07/06/2018 02:46 AM, Loic Pallardy wrote: >>> If rproc_start() failed, rproc_resource_cleanup() is called to clean >>> debugfs entries, then associated iommu mappings, carveouts and vdev. >>> Issue occurs when rproc_free_vring() is trying to reset vring resource >>> table entry. >>> At this time, table_ptr is pointing on loaded resource table and carveouts >>> already released, so access to loaded resource table is generating a kernel >>> paging error: >> >> Are you using a device specific CMA pool or carveout, and if so, where >> the pool is? If not, where is the default CMA pool? I am trying to >> reproduce the issue on my platform with the start failure as you >> suggested, but haven't seen it so far. That said, I have seen the exact >> same crash when using HighMEM CMA pools on my downstream kernel >> when >> stopping the processor, and the root cause is essentially the same as >> what you summarized here. The issue was present with LowMem pools as >> well, but got masked because of the kernel linear mapping. > > I have a carveout declared in firmware resource table for co-processor code and data, and st driver has a specific > reserved memory region to fit fix address space requested by co-processor. > So CPU access to code and loaded resource table area is granted thanks to allocation done by rproc_handle_carveout(). Where are the vrings getting allocated from? In anycase, I prefer that we should actually reset the table_ptr in rproc_start() in failure cases (undo the operation essentially) as we don't call rproc_stop() in those cases. This will result in symmetric code. We already have the reset handled in rproc_stop() added recently in commit 0a8b81cb2e41 ("remoteproc: Reset table_ptr on stop"). Let me know what you think, I can send a quick patch. regards Suman > >> >>> >>> [ 12.696535] Unable to handle kernel paging request at virtual address >> f0f357cc >>> [ 12.696540] pgd = (ptrval) >>> [ 12.696542] [f0f357cc] *pgd=6d2d0811, *pte=00000000, *ppte=00000000 >>> [ 12.696558] Internal error: Oops: 807 [#1] SMP ARM >>> [ 12.696563] Modules linked in: rpmsg_core v4l2_mem2mem >> videobuf2_dma_contig sti_drm v4l2_common vida >>> [ 12.696598] CPU: 1 PID: 48 Comm: kworker/1:1 Tainted: G W >> 4.18.0-rc2-00018-g3170fdd-8 >>> [ 12.696602] Hardware name: STi SoC with Flattened Device Tree >>> [ 12.696625] Workqueue: events request_firmware_work_func >>> [ 12.696659] PC is at rproc_free_vring+0x84/0xbc [remoteproc] >>> [ 12.696667] LR is at rproc_free_vring+0x70/0xbc [remoteproc] >>> >>> This patch proposes to simply remove reset of resource table vring entries, >>> as firmware and resource table are reloaded at each rproc boot. >>> rproc_trigger_recovery() not impacted as resources not touched during >> recovery >>> procedure. >> >> And error recovery doesn't work for me after the rproc_start, stop got >> introduced. > Recovery no available on B2260, but I'll test it on another platform this week > > Regards, > Loic >> >> regards >> Suman >> >>> >>> Signed-off-by: Loic Pallardy >>> --- >>> Changes from V1: typo fixes in commit message >>> >>> drivers/remoteproc/remoteproc_core.c | 6 ------ >>> 1 file changed, 6 deletions(-) >>> >>> diff --git a/drivers/remoteproc/remoteproc_core.c >> b/drivers/remoteproc/remoteproc_core.c >>> index a9609d9..9a8b47c 100644 >>> --- a/drivers/remoteproc/remoteproc_core.c >>> +++ b/drivers/remoteproc/remoteproc_core.c >>> @@ -289,16 +289,10 @@ void rproc_free_vring(struct rproc_vring *rvring) >>> { >>> int size = PAGE_ALIGN(vring_size(rvring->len, rvring->align)); >>> struct rproc *rproc = rvring->rvdev->rproc; >>> - int idx = rvring->rvdev->vring - rvring; >>> - struct fw_rsc_vdev *rsc; >>> >>> dma_free_coherent(rproc->dev.parent, size, rvring->va, rvring- >>> dma); >>> idr_remove(&rproc->notifyids, rvring->notifyid); >>> >>> - /* reset resource entry info */ >>> - rsc = (void *)rproc->table_ptr + rvring->rvdev->rsc_offset; >>> - rsc->vring[idx].da = 0; >>> - rsc->vring[idx].notifyid = -1; >>> } >>> >>> static int rproc_vdev_do_probe(struct rproc_subdev *subdev) >>> >