[PATCH] drm/amd/amdgpu: Fix iova debugfs for non-iommu case

[Christian König]

Am 19.09.2017 um 23:38 schrieb Tom St Denis:
> On 19/09/17 02:33 PM, Christian König wrote:
>>> [root at carrizo ~]# xxd -l 1024 -s 0xC0000 
>>> /sys/kernel/debug/dri/0/amdgpu_iova
>>
>> Actually 0xC0000 is a special address, e.g. video BIOS if I'm not 
>> completely mistaken.
>
> Not sure  why that would be mapped by the driver but I can also read 
> the kernel's bss section with this...
>
> $ xxd -l 1048576 -s 0x01e4c000 /sys/kernel/debug/dri/0/amdgpu_iova
>
> ...<snip>...
> 01e6a430: 4c69 6e75 7820 7665 7273 696f 6e20 342e  Linux version 4.
> 01e6a440: 3133 2e30 2d72 6335 2b20 2872 6f6f 7440  13.0-rc5+ (root@
> 01e6a450: 6361 7272 697a 6f29 2028 6763 6320 7665  carrizo) (gcc ve
> 01e6a460: 7273 696f 6e20 362e 332e 3120 3230 3136  rsion 6.3.1 2016
> 01e6a470: 3132 3231 2028 5265 6420 4861 7420 362e  1221 (Red Hat 6.
> 01e6a480: 332e 312d 3129 2028 4743 4329 2920 2333  3.1-1) (GCC)) #3
> 01e6a490: 3120 534d 5020 5475 6520 5365 7020 3139  1 SMP Tue Sep 19
> 01e6a4a0: 2030 373a 3138 3a33 3120 4544 5420 3230   07:18:31 EDT 20
> <snip>
>
> That's part of the dmesg buffer apparently.
>
> I pointed it at all sorts of address (bios/system ram/etc) it pretty 
> much will read anything.

Yeah, feared that this would be the case. OK in this case your original 
concern was completely correct and we can't allow this in general.

Christian.

>
> Tom
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