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

[Bernard Metzler]

-----"Jason Gunthorpe" <jgg@xxxxxxxx> wrote: -----

>To: "Geert Uytterhoeven" <geert@xxxxxxxxxxxxxx>
>From: "Jason Gunthorpe" <jgg@xxxxxxxx>
>Date: 08/19/2019 02:25PM
>Cc: "Bernard Metzler" <bmt@xxxxxxxxxxxxxx>, "Doug Ledford"
><dledford@xxxxxxxxxx>, linux-rdma@xxxxxxxxxxxxxxx,
>linux-kernel@xxxxxxxxxxxxxxx
>Subject: [EXTERNAL] Re: [PATCH] RDMA/siw: Fix compiler warnings on
>32-bit due to u64/pointer abuse
>
>On Mon, Aug 19, 2019 at 12:05:26PM +0200, Geert Uytterhoeven wrote:
>> When compiling on 32-bit:
>> 
>>     drivers/infiniband/sw/siw/siw_cq.c:76:20: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp.c:952:28: warning: cast from
>pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:53:10: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:59:11: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:59:26: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:61:23: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:62:9: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:82:12: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:87:12: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:101:12: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:169:29: warning: cast
>from pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:192:29: warning: cast
>from pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:204:29: warning: cast
>from pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:219:29: warning: cast
>from pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:476:24: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:535:7: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:832:29: warning: cast
>from pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_qp_tx.c:927:26: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_rx.c:43:5: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_rx.c:43:24: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_rx.c:141:23: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_rx.c:488:6: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_rx.c:601:5: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_qp_rx.c:844:24: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>>     drivers/infiniband/sw/siw/siw_verbs.c:665:22: warning: cast
>from pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_verbs.c:828:19: warning: cast
>from pointer to integer of different size [-Wpointer-to-int-cast]
>>     drivers/infiniband/sw/siw/siw_verbs.c:846:32: warning: cast to
>pointer from integer of different size [-Wint-to-pointer-cast]
>> 
>> Fix this by applying the following rules:
>>   1. When printing a u64, the %llx format specififer should be
>used,
>>      instead of casting to a pointer, and printing the latter.
>>   2. When assigning a pointer to a u64, the pointer should be cast
>to
>>      uintptr_t, not u64,
>>   3. When casting from u64 to pointer, an intermediate cast to
>uintptr_t
>>      should be added,
>> 
>> Fixes: 2c8ccb37b08fe364 ("RDMA/siw: Change CQ flags from 64->32
>bits")
>> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> The issues predate the commit mentioned above, but didn't become
>visible
>> before.
>> 
>> The Right Thing(TM) would be to get rid of all this casting, and
>use
>> proper types instead.
>> This would involve teaching the siw people that a kernel virtual
>address
>> is not called a physical address, and should not use u64.
>>  drivers/infiniband/sw/siw/siw_cq.c    |  5 ++--
>>  drivers/infiniband/sw/siw/siw_qp.c    |  2 +-
>>  drivers/infiniband/sw/siw/siw_qp_rx.c | 16 +++++++------
>>  drivers/infiniband/sw/siw/siw_qp_tx.c | 34
>++++++++++++++-------------
>>  drivers/infiniband/sw/siw/siw_verbs.c |  8 +++----
>>  5 files changed, 35 insertions(+), 30 deletions(-)
>> 
>> diff --git a/drivers/infiniband/sw/siw/siw_cq.c
>b/drivers/infiniband/sw/siw/siw_cq.c
>> index e381ae9b7d62498e..f4ec26eeb9df62bf 100644
>> +++ b/drivers/infiniband/sw/siw/siw_cq.c
>> @@ -71,9 +71,10 @@ int siw_reap_cqe(struct siw_cq *cq, struct ib_wc
>*wc)
>>  				wc->wc_flags = IB_WC_WITH_INVALIDATE;
>>  			}
>>  			wc->qp = cqe->base_qp;
>> -			siw_dbg_cq(cq, "idx %u, type %d, flags %2x, id 0x%p\n",
>> +			siw_dbg_cq(cq,
>> +				   "idx %u, type %d, flags %2x, id 0x%llx\n",
>>  				   cq->cq_get % cq->num_cqe, cqe->opcode,
>> -				   cqe->flags, (void *)cqe->id);
>> +				   cqe->flags, cqe->id);
>
>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.

Thanks and best regards,
Bernard.