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([2401:4900:1cb4:7658:a83f:a091:98a7:4ddd]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7b924aee147sm15589487b3a.13.2025.11.17.23.47.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Nov 2025 23:47:08 -0800 (PST) Message-ID: Date: Tue, 18 Nov 2025 13:17:03 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/msm: adreno: fix deferencing ifpc_reglist when not declared To: Neil Armstrong , Konrad Dybcio Cc: Rob Clark , Sean Paul , Konrad Dybcio , Dmitry Baryshkov , Abhinav Kumar , Jessica Zhang , Marijn Suijten , David Airlie , Simona Vetter , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20251117-topic-sm8x50-fix-a6xx-non-ifpc-v1-1-e4473cbf5903@linaro.org> <04aec988-59ba-4c98-b922-510d86b10ea5@oss.qualcomm.com> <1488f09b-63b7-4412-ba56-28b1c81528ac@linaro.org> Content-Language: en-US From: Akhil P Oommen In-Reply-To: <1488f09b-63b7-4412-ba56-28b1c81528ac@linaro.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: QSsISUJ2BuLla5bv7CXYOQfJlpJlZz9f X-Authority-Analysis: v=2.4 cv=EIELElZC c=1 sm=1 tr=0 ts=691c247e cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=6UeiqGixMTsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=KKAkSRfTAAAA:8 a=O7ohuQCFNY90Bn7chwgA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=rl5im9kqc5Lf4LNbBjHf:22 a=cvBusfyB2V15izCimMoJ:22 X-Proofpoint-GUID: QSsISUJ2BuLla5bv7CXYOQfJlpJlZz9f X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTE4MDA2MCBTYWx0ZWRfX2jhOWq4qQlzD bvxIfQfZDpT7cos+6b/wF3pHYPX9q0kDVqaYnUcb91yn6l3B/b0JQeEBjHwJTrlAGcuLzhPzD8K 7EvuAJaO416SaPLtB1evT89jpJNKy2cZNe4gGGgJHZKoBmjUWQsk9esyE6ctP/rfSQ6HDx2aTmp sH+S6C+isGK19uC4ue492IBxPjurZyDDulo30hJD2KjrTacpXb9ZJvprJCALnT1T9RkMp+/zn6/ q2QJ0G4eT2Pp40bdDDHUlGpumCpuJ1CND0lzJMz3nG9k40zAOogc/sMkkVA6JeMlRfn5hCRbZ6b VP+KTUOLCDxo3hvqfMAuQnct1Sdgi1wUuHyGpHGe7stnAs8ZPzPIAptnXVZFzz3Y6XtjhqJRSx3 jd8W+iC2rne5ep6CYDs89C37pVyD/A== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-17_04,2025-11-13_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 spamscore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 phishscore=0 impostorscore=0 adultscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2510240001 definitions=main-2511180060 On 11/17/2025 9:17 PM, Neil Armstrong wrote: > On 11/17/25 16:02, Konrad Dybcio wrote: >> On 11/17/25 3:51 PM, Neil Armstrong wrote: >>> On plaforms with an a7xx GPU not supporting IFPC, the ifpc_reglist >>> if still deferenced in a7xx_patch_pwrup_reglist() which causes >>> a kernel crash: >>> Unable to handle kernel NULL pointer dereference at virtual address >>> 0000000000000008 >>> ... >>> pc : a6xx_hw_init+0x155c/0x1e4c [msm] >>> lr : a6xx_hw_init+0x9a8/0x1e4c [msm] >>> ... >>> Call trace: >>>    a6xx_hw_init+0x155c/0x1e4c [msm] (P) >>>    msm_gpu_hw_init+0x58/0x88 [msm] >>>    adreno_load_gpu+0x94/0x1fc [msm] >>>    msm_open+0xe4/0xf4 [msm] >>>    drm_file_alloc+0x1a0/0x2e4 [drm] >>>    drm_client_init+0x7c/0x104 [drm] >>>    drm_fbdev_client_setup+0x94/0xcf0 [drm_client_lib] >>>    drm_client_setup+0xb4/0xd8 [drm_client_lib] >>>    msm_drm_kms_post_init+0x2c/0x3c [msm] >>>    msm_drm_init+0x1a4/0x228 [msm] >>>    msm_drm_bind+0x30/0x3c [msm] >>> ... >>> >>> Check the validity of ifpc_reglist before deferencing the table >>> to setup the register values. >>> >>> Fixes: a6a0157cc68e ("drm/msm/a6xx: Enable IFPC on Adreno X1-85") >>> Signed-off-by: Neil Armstrong >>> --- >> >> I think it should be fine to skip calling this func altogether >> if !ifpc || !pwrup_reglist >> >> Although ifpc && !pwrup_reglist should probably scream very loud That's correct. It is a weird combo. > > Sorry but why? pwrup_reglist was introduced way earlier than IFPC. Pwrup list is shared with preemption feature too. And preemption support was introduced before IFPC. nit: It is nice to have a similar NULL check for pwrup reglist too. We sometimes skip these during initial GPU bringup (like A840 for eg:). -Akhil > > Why would we be skipping the a7xx_patch_pwrup_reglist() because > ifpc_reglist is not declared ??? > > Neil > >> >> Konrad >