[PATCH] drm/etnaviv: Fix the pm_domain lookup

[Christian Gmeiner]

Hi Lubomir


Am Do., 14. Mai 2020 um 00:02 Uhr schrieb Lubomir Rintel <lkundrak at v3.sk>:
>
> On a GC860 (both 3D and 2D capable) GPU, kmscube crashes:
>
>   # strace -f ~lkundrak/src/kmscube/build/kmscube
>   ...
>   ioctl(6, DRM_IOCTL_ETNAVIV_PM_QUERY_DOM, 0xbe92b720) = 0
>   ioctl(6, DRM_IOCTL_ETNAVIV_PM_QUERY_SIG <unfinished ...>) = ?
>   +++ killed by SIGSEGV +++
>   Segmentation fault (core dumped)
>
> And triggers an oops:
>
>   8<--- cut here ---
>   Unable to handle kernel NULL pointer dereference at virtual address 00000000
>   pgd = 40e2c0f7
>   [00000000] *pgd=0df6d831, *pte=00000000, *ppte=00000000
>   Internal error: Oops: 17 [#1] PREEMPT SMP ARM
>   Modules linked in:
>   CPU: 0 PID: 346 Comm: kmscube Not tainted 5.7.0-rc4+ #792
>   Hardware name: Marvell MMP2 (Device Tree Support)
>   PC is at strncpy+0x14/0x30
>   LR is at etnaviv_pm_query_sig+0xd0/0x104
>   pc : [<c04f35f4>]    lr : [<c05dd878>]    psr: 20010013
>   sp : c85f5e00  ip : c85f5eb5  fp : beb58748
>   r10: 0000004c  r9 : ca6f9100  r8 : c85f5e6c
>   r7 : 00000050  r6 : c85f5e6c  r5 : 00000001  r4 : c0b69ae8
>   r3 : c85f5e75  r2 : 0000003f  r1 : 00000000  r0 : c85f5e76
>   Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
>   Control: 10c5387d  Table: 0df70019  DAC: 00000051
>   Process kmscube (pid: 346, stack limit = 0x816fba31)
>   Stack: (0xc85f5e00 to 0xc85f6000)
>   5e00: 00000000 d90e6000 00000020 c05d5b2c c85f5e6c c059ce90 00000000 c1003f88
>   5e20: c04c644b 0000004c c0b69610 c04c644b c85f5e6c 0000004b ca6f9100 c059d0bc
>   5e40: 00000001 c0d53ee8 c85f5f18 00000001 c85f5f50 c85f5e6c 0000004c c8454240
>   5e60: c05d5b2c 00000051 00000000 00000000 00000001 00000000 00000000 00000000
>   5e80: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
>   5ea0: 00000000 00000000 00000000 00000000 00000000 00000000 00000274 c011c3fc
>   5ec0: 00000100 c0290434 5ebc5632 30e03501 5ebc5632 c8526600 00000274 00100cca
>   5ee0: 00000831 b64c5000 cdf72d90 c1003f88 00000000 c04c644b c8454240 beb58748
>   5f00: c8454240 00000006 c85f4000 d90ecad8 001c01a0 c02d49ac b64c52cc 80000007
>   5f20: da9d6dc0 d9aa4000 d9aa4040 00000000 00000274 c011818c 00000005 0e200080
>   5f40: 00000000 000003e5 00000000 00000100 00000000 00000000 00000000 cc78ac40
>   5f60: 00000006 00000007 c1009a98 b64c52cc c85f5fb0 c0118080 00000080 c1003f88
>   5f80: 00000000 00000001 beb58748 c04c644b 00000036 c0100288 c85f4000 00000036
>   5fa0: 001c01a0 c0100060 00000001 beb58748 00000006 c04c644b beb58748 0000004c
>   5fc0: 00000001 beb58748 c04c644b 00000036 beb58748 001bd688 beb58700 001c01a0
>   5fe0: b6f41f08 beb586d4 b6f2784c b6e16cec 80010010 00000006 00000000 00000000
>   [<c04f35f4>] (strncpy) from [<c05dd878>] (etnaviv_pm_query_sig+0xd0/0x104)
>   [<c05dd878>] (etnaviv_pm_query_sig) from [<c059ce90>] (drm_ioctl_kernel+0xb4/0xf8)
>   [<c059ce90>] (drm_ioctl_kernel) from [<c059d0bc>] (drm_ioctl+0x1e8/0x3b8)
>   [<c059d0bc>] (drm_ioctl) from [<c02d49ac>] (ksys_ioctl+0xe0/0xaf0)
>   [<c02d49ac>] (ksys_ioctl) from [<c0100060>] (ret_fast_syscall+0x0/0x54)
>   Exception stack(0xc85f5fa8 to 0xc85f5ff0)
>   5fa0:                   00000001 beb58748 00000006 c04c644b beb58748 0000004c
>   5fc0: 00000001 beb58748 c04c644b 00000036 beb58748 001bd688 beb58700 001c01a0
>   5fe0: b6f41f08 beb586d4 b6f2784c b6e16cec
>   Code: 012fff1e e2422001 e2403001 e080c002 (e5d12000)
>   ---[ end trace 387aad33cd9c15ea ]---
>
> Turns out that it's because pm_domain() returns a pointer outside any
> any of the etnaviv_pm_domains. Unless I'm mistaken, the algorithm in
> pm_domain() is entirely botched when GPU's features match more than one
> domain. This tries to remedy it.
>
> Tested with kmscube with mesa 20 on ome machine with GC860 and another
> with GC2000 + GC300 pair.
>
> Signed-off-by: Lubomir Rintel <lkundrak at v3.sk>

There is already an older/other fix for this problem:
https://patchwork.freedesktop.org/patch/365181/

-- 
greets
--
Christian Gmeiner, MSc

https://christian-gmeiner.info/privacypolicy