Re: [Patch] MdePkg/BaseSafeIntLib: Fix VS20xx IA32 link failures

["Liming Gao" <liming.gao@intel.com>]

Reviewed-by: Liming Gao <liming.gao@intel.com>

> -----Original Message-----
> From: Kinney, Michael D <michael.d.kinney@intel.com>
> Sent: Thursday, February 13, 2020 6:45 AM
> To: devel@edk2.groups.io
> Cc: Gao, Liming <liming.gao@intel.com>; Sean Brogan <sean.brogan@microsoft.com>; Bret Barkelew <Bret.Barkelew@microsoft.com>
> Subject: [Patch] MdePkg/BaseSafeIntLib: Fix VS20xx IA32 link failures
> 
> https://bugzilla.tianocore.org/show_bug.cgi?id=2525
> 
> SafeUint64Mult() looks for 64-bit overflows and performs
> several 32-bit multiples with 64-bit results to check for
> all possible overflow conditions.  IA32 builds using VS20xx
> with optimizations enabled are producing a reference to
> the _allmull intrinsic.
> 
> The fix is to use MultU64x64() instead of '*' for
> these operations.  These are safe because the inputs
> are guaranteed to have the upper 32-bits clear, which
> means MultU64x64() can never overflow with those inputs.
> 
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Sean Brogan <sean.brogan@microsoft.com>
> Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
> Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
> ---
>  MdePkg/Library/BaseSafeIntLib/SafeIntLib.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
> index 0f6be6e064..eec8ac1ffd 100644
> --- a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
> +++ b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
> @@ -3380,14 +3380,14 @@ SafeUint64Mult (
>        //
>        // a * d must be less than 2^32 or there would be bits set in the high 64-bits
>        //
> -      ProductAD = (((UINT64)DwordA) *(UINT64)DwordD);
> +      ProductAD = MultU64x64 ((UINT64)DwordA, (UINT64)DwordD);
>        if ((ProductAD & 0xffffffff00000000) == 0) {
>          DwordB = (UINT32)Multiplicand;
> 
>          //
>          // b * c must be less than 2^32 or there would be bits set in the high 64-bits
>          //
> -        ProductBC = (((UINT64)DwordB) *(UINT64)DwordC);
> +        ProductBC = MultU64x64 ((UINT64)DwordB, (UINT64)DwordC);
>          if ((ProductBC & 0xffffffff00000000) == 0) {
>            //
>            // now sum them all up checking for overflow.
> @@ -3397,7 +3397,7 @@ SafeUint64Mult (
>              //
>              // b * d
>              //
> -            ProductBD = (((UINT64)DwordB) *(UINT64)DwordD);
> +            ProductBD = MultU64x64 ((UINT64)DwordB, (UINT64)DwordD);
> 
>              if (!RETURN_ERROR (SafeUint64Add (UnsignedResult, ProductBD, &UnsignedResult))) {
>                *Result = UnsignedResult;
> --
> 2.21.0.windows.1