linux-kernel - Re: Re: Re: [PATCH] RDMA/siw: Fix compiler warnings on 32-bit due to u64/pointer abuse

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Date:   Mon, 19 Aug 2019 11:18:56 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Bernard Metzler <BMT@...ich.ibm.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Doug Ledford <dledford@...hat.com>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Re: Re: [PATCH] RDMA/siw: Fix compiler warnings on 32-bit due to
 u64/pointer abuse

On Mon, Aug 19, 2019 at 02:15:36PM +0000, Bernard Metzler wrote:
> 
> >To: "Bernard Metzler" <BMT@...ich.ibm.com>
> >From: "Jason Gunthorpe" <jgg@...pe.ca>
> >Date: 08/19/2019 03:52PM
> >Cc: "Geert Uytterhoeven" <geert@...ux-m68k.org>, "Doug Ledford"
> ><dledford@...hat.com>, linux-rdma@...r.kernel.org,
> >linux-kernel@...r.kernel.org
> >Subject: [EXTERNAL] Re: Re: [PATCH] RDMA/siw: Fix compiler warnings
> >on 32-bit due to u64/pointer abuse
> >
> >On Mon, Aug 19, 2019 at 01:36:11PM +0000, Bernard Metzler wrote:
> >> >If the value is really a kernel pointer, then it ought to be
> >printed
> >> >with %p. We have been getting demanding on this point lately in
> >RDMA
> >> >to enforce the ability to keep kernel pointers secret.
> >> >
> >> >> -			wqe->sqe.sge[0].laddr = (u64)&wqe->sqe.sge[1];
> >> >> +			wqe->sqe.sge[0].laddr = (uintptr_t)&wqe->sqe.sge[1];
> >> >
> >> >[..]
> >> >
> >> >>  			rv = siw_rx_kva(srx,
> >> >> -					(void *)(sge->laddr + frx->sge_off),
> >> >> +					(void *)(uintptr_t)(sge->laddr + frx->sge_off),
> >> >>  					sge_bytes);
> >> >
> >> >Bernard, this is nonsense, what is going on here with sge->laddr
> >that
> >> >it can't be a void *?
> >> >
> >> siw_sge is defined in siw-abi.h. We make the address u64 to keep
> >the ABI
> >> arch independent.
> >
> >Eh? How does the siw-abi.h store a kernel pointer? Sounds like kernel
> >and user types are being mixed.
> >
> 
> siw-abi.h defines the work queue elements of a siw send queue.
> For user land, the send queue is mmapped. Kernel or user land
> clients write to its send queue when posting work
> (SGE: buffer address, length, local key). 

Should have different types.. Don't want to accidently mix a laddr
under user control with one under kernel control.

Jason