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Subject: Re: [RFC PATCH 2/3] powerpc/pseries: Define & use a type for the
 plpar_hcall() retvals
To: Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@ozlabs.org
References: <1476780032-21643-1-git-send-email-mpe@ellerman.id.au>
 <1476780032-21643-2-git-send-email-mpe@ellerman.id.au>
From: Balbir Singh <bsingharora@gmail.com>
Message-ID: <b922cd6c-a44d-6950-93d7-6645fd1f7fac@gmail.com>
Date: Wed, 19 Oct 2016 01:17:11 +1100
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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
Balbir