Re: [PATCH v4 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context

[Shuai Xue <xueshuai@linux.alibaba.com>]

在 2025/3/8 07:22, Borislav Petkov 写道:
> On Fri, Mar 07, 2025 at 11:11:26PM +0000, Luck, Tony wrote:
>> As for "explicit markup" I don't think it would be better to decorate
>> every get_user() and copy_from_user() with some "this one can
>> recover from #MC"
> 
> I don't mean every function - I mean what we had there with EX_TYPE_UACCESS.
> That is explicit and unambiguous. Proving that is_copy_from_user() is always
> correct is a lot harder.
> 
>> Note also that "what we had recently" was fragile, broke, and resulted
>> in this regression.
> 
> Because those exception types got renamed? Oh well, that should've been
> reverted actually but no one involved realized that MCE is using those.
> 
> And I'm not saying this is the only way to solve this. We could do something
> like collecting all addresses on which an MCE can be recoverable, for example.
> We haven't considered it that important... yet.
> 
> Looks like we're going to try this new is_copy_from_user() thing now and then
> see where it gets us.
> 
> So, after the commit message has been fixed:
> 
> Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
> 
> I'm presuming, this is going through akpm...
> 

Thanks.
Shuai