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

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Message-Id: <OFD7D2994B.750F3146-ON0025845B.004D965D-0025845B.004E5577@notes.na.collabserv.com>
Date:   Mon, 19 Aug 2019 14:15:36 +0000
From:   "Bernard Metzler" <BMT@...ich.ibm.com>
To:     "Jason Gunthorpe" <jgg@...pe.ca>
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

-----"Jason Gunthorpe" <jgg@...pe.ca> 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). 

Thanks,
Bernard.