[PATCH] powerpc: Avoid code patching freed init sections

[Christophe LEROY]

Le 10/09/2018 à 12:05, Michael Neuling a écrit :
> 
>>> +	/* Make sure we aren't patching a freed init section */
>>> +	if (in_init_section(patch_addr) && init_freed())
>>> +		return 0;
>>> +
>>
>> Do we even need the init_freed() check?
> 
> Maybe not.  If userspace isn't up, then maybe it's ok to skip.

Euh ... Do you mean you'll skip all patches into init functions ?
But code patching is not only for meltdown/spectrum workarounds, some of 
the patchings might be needed for the init functions themselves.

Christophe

> 
>> What user input can we process in init-only code?
> 
> See the stack trace in the commit message. It's a weird case for KVM guests in
> KVM PR mode.
> 
> That's the only case I can found so far.
> 
>> Also it would be nice to write the function+offset of the skipped patch
>> location into the kernel log.
> 
> OK. I'll update.
> 
> Mikey
>