NULL pointer dereference in etnaviv_iommu_context_init (v5.4.105)

[Frieder Schrempf]

Hello Lucas,

I have a report from a customer running kernel 5.4.105 on i.MX8MM with
the stack trace below. Do you know something about this or can you give
a guess?

I saw that there are fixes from you targeting MMU context handling that
were merged recently, but aren't in the stable tree, yet. Could this be
related?

Thanks
Frieder

[    5.172688] Unable to handle kernel NULL pointer dereference at
virtual address 0000000000000008
[    5.172697] Mem abort info:
[    5.172699]   ESR = 0x96000004
[    5.172702]   EC = 0x25: DABT (current EL), IL = 32 bits
[    5.172704]   SET = 0, FnV = 0
[    5.172706]   EA = 0, S1PTW = 0
[    5.172707] Data abort info:
[    5.172709]   ISV = 0, ISS = 0x00000004
[    5.172710]   CM = 0, WnR = 0
[    5.172714] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000b7e01000
[    5.172716] [0000000000000008] pgd=0000000000000000
[    5.172721] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[    5.178295] Modules linked in: powersupply(O) nsam(O) egalax_i2c(O)
GobiSerial(O) GobiNet(O)
[    5.186762] CPU: 2 PID: 313 Comm: Xorg Tainted: G           O
5.4.105-gnt #1
[    5.194265] Hardware name: ## redacted ##
[    5.194269] pstate: 40000005 (nZcv daif -PAN -UAO)
[    5.194281] pc : etnaviv_iommu_context_init+0x18/0xc8
[    5.194291] lr : etnaviv_open+0x50/0xe8
[    5.213198] sp : ffff800011b43a00
[    5.213204] x29: ffff800011b43a00 x28: 0000000000000000
[    5.221850] x27: 0000000000000002 x26: ffff800011b43d10
[    5.221855] x25: 0000000000000000 x24: ffff00007a1c3200
[    5.221858] x23: 000000007c2e0100 x22: ffff000077e08000
[    5.221861] x21: ffff00007c2e0400 x20: 0000000000000000
[    5.221864] x19: ffff00007c2e0380 x18: 0000000000000000
[    5.221867] x17: 0000000000000000 x16: 0000000000000000
[    5.221870] x15: 0000000000000000 x14: 0000000000000000
[    5.221873] x13: ffff000077e08000 x12: 0000000000000000
[    5.221876] x11: 0000000000000001 x10: 0000000000000040
[    5.221878] x9 : 0000000000000000 x8 : ffff00007a317400
[    5.221881] x7 : 0000000000000000 x6 : 000000000000003f
[    5.221884] x5 : 0000000000000040 x4 : 0000000000000000
[    5.221887] x3 : 0000000000000004 x2 : 0000000000000000
[    5.221890] x1 : ffff00007c2e0400 x0 : 0000000000000000
[    5.221894] Call trace:
[    5.221906]  etnaviv_iommu_context_init+0x18/0xc8
[    5.221911]  etnaviv_open+0x50/0xe8
[    5.221917]  drm_file_alloc+0x11c/0x1e0
[    5.221920]  drm_open+0x94/0x198
[    5.221924]  drm_stub_open+0xb4/0xf8
[    5.221930]  chrdev_open+0xa0/0x198
[    5.221934]  do_dentry_open+0x110/0x3b0
[    5.221936]  vfs_open+0x28/0x30
[    5.221940]  path_openat+0x4b8/0x1280
[    5.221943]  do_filp_open+0x74/0xf8
[    5.221946]  do_sys_open+0x168/0x218
[    5.221949]  __arm64_sys_openat+0x20/0x28
[    5.221955]  el0_svc_common.constprop.0+0x68/0x160
[    5.221958]  el0_svc_handler+0x20/0x80
[    5.221962]  el0_svc+0x8/0x204
[    5.221970] Code: a90153f3 aa0003f4 a9025bf5 aa0103f5 (b9400801)
[    5.221975] ---[ end trace 0d8e2dcf004ee953 ]---