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SubjectRe: [PATCH][v4] uprobes/x86: emulate push insns for uprobe on x86
Hi, Ingo and Peter,

This patch has been reviewed by Oleg Nesterov. Could you
take a look and help merge it upstream?



On 11/20/17 10:25 AM, Yonghong Song wrote:
> On 11/20/17 8:41 AM, Oleg Nesterov wrote:
>> On 11/17, Yonghong Song wrote:
>>> On 11/17/17 9:25 AM, Oleg Nesterov wrote:
>>>> On 11/15, Yonghong Song wrote:
>>>>> v3 -> v4:
>>>>>    . Revert most of v3 change as 32bit emulation is not really working
>>>>>      on x86_64 platform as among other issues, function
>>>>> emulate_push_stack()
>>>>>      needs to account for 32bit app on 64bit platform.
>>>>>      A separate effort is ongoing to address this issue.
>>>> Reviewed-by: Oleg Nesterov <>
>>>> Please test your patch with the fix below, in this particular case the
>>>> TIF_IA32 check should be fine. Although this is not what we really
>>>> want,
>>>> we should probably use user_64bit_mode(regs) which checks ->cs. But
>>>> this
>>>> needs more changes and doesn't solve other problems (get_unmapped_area)
>>>> so I still can't decide what should we do right now...
>>> I tested the below change with my patch. On x86_64, both 64bit and 32bit
>>> program can be uprobe emulated properly.
>> Good, so your patch is fine.
> Thanks!
>>> On x86_32, however, there is a
>>> compilation error like below:
>> Yes, yes, when I said "in this particular case" I meant x86_64 system
>> only.
>> Sorry for confusion, I asked you to test this additional change just to
>> ensure that we didn't miss something and your patch has no problems with
>> 32bit tasks on 64bit system, except those we need to fix anyway.
> Understood. I actually tried a little to see whether I could have a
> simple way to fix 32bit compilation error without using ugly "#ifdef
> CONFIG_X86_64". Maybe is_64bit_mm is a good choice. But we could defer
> this until you have a comprehensive fix for 32bit app uprobe on 64bit
> systems as there are multiple issues for this.
>> Oleg.

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