On Mon, Oct 9, 2017 at 1:40 PM, Marek Szyprowski
<m.szyprowski@xxxxxxxxxxx> wrote:
> Exynos SYSMMU registers standard platform device with sysmmu_of_match
> table, what means that this table is accessed every time a new platform
> device is registered in a system. This might happen also after the boot,
> so the table must not be attributed as initconst to avoid potential kernel
> oops caused by access to freed memory.
>
> Fixes: 6b21a5db3642 ("iommu/exynos: Support for device tree")
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> Hi!
>
> This issue was there from the beggining of the device tree
> support, I'm really surprised that it has not been noticed it till
> now. This patch fixes the following hard-to-debug kernel issue:
>
> Unable to handle kernel paging request at virtual address ffffff80090fb018
> Mem abort info:
> Exception class = DABT (current EL), IL = 32 bits
> SET = 0, FnV = 0
> EA = 0, S1PTW = 0
> Data abort info:
> ISV = 0, ISS = 0x00000007
> CM = 0, WnR = 0
> swapper pgtable: 4k pages, 39-bit VAs, pgd = ffffff80097f9000
> [ffffff80090fb018] *pgd=00000008ffffe003, *pud=00000008ffffe003, *pmd=00000008ffffb003, *pte=0000000000000000
> Internal error: Oops: 96000007 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 7 PID: 102 Comm: kworker/7:1 Tainted: G S 4.14.0-rc1+ #4572
> Hardware name: Samsung DREAMLTE EUR rev10 board based on EXYNOS8895 (DT)
> Workqueue: events deferred_probe_work_func
> task: ffffffc87a7f1b00 task.stack: ffffff8009b88000
> PC is at __of_match_node+0x24/0x7c
> LR is at of_match_node+0x38/0x5c
> pc : [<ffffff800871ac6c>] lr : [<ffffff800871acfc>] pstate: a00001c5
> sp : ffffff8009b8bba0
> x29: ffffff8009b8bba0 x28: ffffffc87ff8fc00
> x27: ffffff80095c7000 x26: ffffff80096e76e0
> x25: ffffff8008f1e7a0 x24: ffffff800965d000
> x23: ffffff800977d008 x22: 0000000000000000
> x21: ffffffc87ffcd598 x20: 0000000000000000
> x19: ffffff80090fb018 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000
> x15: 0000000000000008 x14: 0000000000000000
> x13: 0000000000000040 x12: 0000000000000038
> x11: 0000000000000001 x10: 0101010101010101
> x9 : 06fefeff01fefeff x8 : 7f7f7f7f7f7f7f7f
> x7 : 2f2f2f2f382f3030 x6 : 4354571454455d5d
> x5 : 5d5d455414575443 x4 : ffffff8009b8c000
> x3 : ffffff8009b88000 x2 : 0000000000000000
> x1 : ffffffc87ffcd598 x0 : ffffff80090fb018
> Process kworker/7:1 (pid: 102, stack limit = 0xffffff8009b88000)
> Call trace:
> Exception stack(0xffffff8009b8ba60 to 0xffffff8009b8bba0)
> ba60: ffffff80090fb018 ffffffc87ffcd598 0000000000000000 ffffff8009b88000
> ba80: ffffff8009b8c000 5d5d455414575443 4354571454455d5d 2f2f2f2f382f3030
> baa0: 7f7f7f7f7f7f7f7f 06fefeff01fefeff 0101010101010101 0000000000000001
> bac0: 0000000000000038 0000000000000040 0000000000000000 0000000000000008
> bae0: 0000000000000000 0000000000000000 0000000000000000 ffffff80090fb018
> bb00: 0000000000000000 ffffffc87ffcd598 0000000000000000 ffffff800977d008
> bb20: ffffff800965d000 ffffff8008f1e7a0 ffffff80096e76e0 ffffff80095c7000
> bb40: ffffffc87ff8fc00 ffffff8009b8bba0 ffffff800871acfc ffffff8009b8bba0
> bb60: ffffff800871ac6c 00000000a00001c5 ffffffc800000000 ffffff800871acec
> bb80: ffffffffffffffff ffffff800871acec ffffff8009b8bba0 ffffff800871ac6c
> [<ffffff800871ac6c>] __of_match_node+0x24/0x7c
> [<ffffff800871acfc>] of_match_node+0x38/0x5c
> [<ffffff800871c5d0>] of_match_device+0x18/0x28
> [<ffffff80085031c0>] platform_match+0x4c/0xc8
> [<ffffff8008500c68>] __device_attach_driver+0x3c/0x138
> [<ffffff80084fe7a0>] bus_for_each_drv+0x54/0x94
> [<ffffff8008500510>] __device_attach+0xc4/0x154
> [<ffffff8008500d74>] device_initial_probe+0x10/0x18
> [<ffffff80084ff844>] bus_probe_device+0x90/0x98
> [<ffffff80084ffdf8>] deferred_probe_work_func+0x64/0x18c
> [<ffffff80080b5f24>] process_one_work+0x150/0x3dc
> [<ffffff80080b6208>] worker_thread+0x58/0x3b8
> [<ffffff80080bbbc4>] kthread+0x104/0x130
> [<ffffff8008085340>] ret_from_fork+0x10/0x20
> Code: aa0103f5 b40002a0 52800014 d2800016 (39400264)
> ---[ end trace 4a748776163027e1 ]---
>
> I'm not sure however if it makes sense to add the above kernel log to the
> commit message as it doesn't directly point to the code fixed by this patch.
>
> Best regards
> Marek Szyprowski
> Samsung R&D Institute Poland
> ---
> drivers/iommu/exynos-iommu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
Best regards,
Krzysztof
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