[RFC PATCH 2/3] powerpc/pseries: Define & use a type for the plpar_hcall() retvals

[Michael Ellerman]

Balbir Singh <bsingharora at gmail.com> writes:

> On 18/10/16 19:40, Michael Ellerman wrote:
>> We have now had two nasty stack corruption bugs caused by incorrect
>> sizing of the return buffer for plpar_hcall()/plpar_hcall9().
>> 
>> To avoid any more such bugs, define a type which encodes the size of the
>> return buffer, and change the argument of plpar_hcall() to be of that
>> type, meaning the compiler will check for us that we passed the right
>> size buffer.
>> 
>> There isn't an easy way to do this incrementally, without introducing a
>> new function name, eg. plpar_hcall_with_struct(), which is ugly as hell.
>> So just do it in one tree-wide change.
>> 
> Conceptually looks god, but I think we need to abstract the return values
> as well. I'll test and see if I can send you something on top of this

Not sure I know what you mean.

cheers