Re: [PATCH 4/5] MdeModulePkg/PartitionDxe: don't divide 64-bit values with C operators

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

Thanks/Ray

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Tuesday, September 12, 2017 3:59 PM
> To: Bi, Dandan <dandan.bi@intel.com>; edk2-devel-01 <edk2-
> devel@lists.01.org>
> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Dong, Eric <eric.dong@intel.com>; Zeng,
> Star <star.zeng@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Subject: Re: [edk2] [PATCH 4/5] MdeModulePkg/PartitionDxe: don't divide
> 64-bit values with C operators
> 
> On 09/12/17 07:41, Bi, Dandan wrote:
> > Hi Laszlo,
> >
> > When do you plan to push this patch? IA32 build is blocked for this issue
> now.
> 
> I was ready to push the series yesterday; I just hoped I'd get review
> feedback from MdeModulePkg maintainers as well, and/or from Ray, in one
> or two days.
> 
> These are strongly localized changes that require no knowledge of the UDF
> driver. (I don't have that knowledge myself, to begin with.) At least an
> Acked-by would be nice.
> 
> If someone from Intel tells me I can push this with the R-b's that are currently
> on the list, I'm totally game.
> 
> Thanks!
> Laszlo
> 
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> > Laszlo Ersek
> > Sent: Sunday, September 10, 2017 8:13 AM
> > To: edk2-devel-01 <edk2-devel@lists.01.org>
> > Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Dong, Eric <eric.dong@intel.com>;
> > Zeng, Star <star.zeng@intel.com>; Ard Biesheuvel
> > <ard.biesheuvel@linaro.org>
> > Subject: [edk2] [PATCH 4/5] MdeModulePkg/PartitionDxe: don't divide
> > 64-bit values with C operators
> >
> > In edk2, the division and shifting of 64-bit values are forbidden with C-
> language operators, because the compiler may generate intrinsic calls for
> them.
> >
> > For example, clang-3.8 emits a call to "__umoddi3" for
> >
> >   UDF_LOGICAL_SECTOR_SIZE % Media->BlockSize
> >
> > in PartitionInstallUdfChildHandles(), if PartitionDxe is built for IA32, which
> then fails to link.
> >
> > UDF_LOGICAL_SECTOR_SIZE has type UINT64, while
> EFI_BLOCK_IO_MEDIA.BlockSize has type UINT32(). Replace the % operator
> with a DivU64x32Remainder() call.
> >
> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Paulo Alcantara <pcacjr@zytor.com>
> > Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> > Cc: Star Zeng <star.zeng@intel.com>
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> > ---
> >  MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
> > b/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
> > index c1d44809bfd2..c491ef25f47e 100644
> > --- a/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
> > +++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Udf.c
> > @@ -234,10 +234,11 @@ PartitionInstallUdfChildHandles (
> >    IN  EFI_BLOCK_IO_PROTOCOL        *BlockIo,
> >    IN  EFI_BLOCK_IO2_PROTOCOL       *BlockIo2,
> >    IN  EFI_DEVICE_PATH_PROTOCOL     *DevicePath
> >    )
> >  {
> > +  UINT32                       RemainderByMediaBlockSize;
> >    EFI_STATUS                   Status;
> >    EFI_BLOCK_IO_MEDIA           *Media;
> >    EFI_DEVICE_PATH_PROTOCOL     *DevicePathNode;
> >    EFI_GUID                     *VendorDefinedGuid;
> >    EFI_GUID                     UdfDevPathGuid = EFI_UDF_DEVICE_PATH_GUID;
> > @@ -246,11 +247,16 @@ PartitionInstallUdfChildHandles (
> >    Media = BlockIo->Media;
> >
> >    //
> >    // Check if UDF logical block size is multiple of underlying device block size
> >    //
> > -  if ((UDF_LOGICAL_SECTOR_SIZE % Media->BlockSize) != 0 ||
> > +  DivU64x32Remainder (
> > +    UDF_LOGICAL_SECTOR_SIZE,   // Dividend
> > +    Media->BlockSize,          // Divisor
> > +    &RemainderByMediaBlockSize // Remainder
> > +    );
> > +  if (RemainderByMediaBlockSize != 0 ||
> >        Media->BlockSize > UDF_LOGICAL_SECTOR_SIZE) {
> >      return EFI_NOT_FOUND;
> >    }
> >
> >    DevicePathNode = DevicePath;
> > --
> > 2.14.1.3.gb7cf6e02401b
> >
> >
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