Re: [edk2-devel] [PATCH v1 1/1] UefiCpuPkg: Clean up save state boundary checks and comments.

["Laszlo Ersek" <lersek@redhat.com>]

On 10/19/20 20:03, Laszlo Ersek wrote:
> Hi Mark,
> 
> On 10/15/20 18:32, Mark Wilson wrote:
>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2956
>>
>> In functions ReadSaveStateRegisterByIndex and WriteSaveStateRegister:
>> * check width > 4 instead of >= 4 when writing upper 32 bytes.
>>   - This improves the code but will not affect functionality.
>> * Update related comments to better describe code.
>>
>> Cc: Eric Dong <eric.dong@intel.com>
>> Cc: Ray Ni <ray.ni@intel.com>
>> Signed-off-by: Mark Wilson <Mark.Wilson@amd.com>
>> ---
>>  UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c | 26 ++++++++++----------
>>  1 file changed, 13 insertions(+), 13 deletions(-)
> 
> I suggest separating the cosmetic changes (such as the whitespace fixes)
> from the cleanups (comments etc) to different patches.
> 
> Also, please run "BaseTools/Scripts/SetupGit.py" in your edk2 clone.

Furthermore, I suggest a bit more specific subject:

UefiCpuPkg/PiSmmCpuDxeSmm: clean up save state boundary checks and comments

(I think this subject length, i.e. 75 characters, should still satisfy "PatchCheck.py".)

Sorry about the piecemeal observations; trying to deal with a bit of a backlog.

Thanks
Laszlo

>>
>> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c
>> index 661cc51f361a..4a872e400b7a 100644
>> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c
>> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c
>> @@ -297,8 +297,8 @@ ReadSaveStateRegisterByIndex (
>>      //
>>
>>      // Write return buffer
>>
>>      //
>>
>> -    ASSERT(CpuSaveState != NULL);
>>
>> -    CopyMem(Buffer, (UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset32, Width);
>>
>> +    ASSERT (CpuSaveState != NULL);
>>
>> +    CopyMem (Buffer, (UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset32, Width);
>>
>>    } else {
>>
>>      //
>>
>>      // If 64-bit mode width is zero, then the specified register can not be accessed
>>
>> @@ -315,14 +315,14 @@ ReadSaveStateRegisterByIndex (
>>      }
>>
>>  
>>
>>      //
>>
>> -    // Write lower 32-bits of return buffer
>>
>> +    // Write at most 4 of the lower bytes of the return buffer
>>
>>      //
>>
>> -    CopyMem(Buffer, (UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Lo, MIN(4, Width));
>>
>> -    if (Width >= 4) {
>>
>> +    CopyMem (Buffer, (UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Lo, MIN(4, Width));
>>
>> +    if (Width > 4) {
>>
>>        //
>>
>> -      // Write upper 32-bits of return buffer
>>
>> +      // Write at most 4 of the upper bytes of the return buffer
>>
>>        //
>>
>> -      CopyMem((UINT8 *)Buffer + 4, (UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Hi, Width - 4);
>>
>> +      CopyMem ((UINT8 *)Buffer + 4, (UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Hi, Width - 4);
>>
>>      }
>>
>>    }
>>
>>    return EFI_SUCCESS;
>>
>> @@ -522,7 +522,7 @@ WriteSaveStateRegister (
>>      // Write SMM State register
>>
>>      //
>>
>>      ASSERT (CpuSaveState != NULL);
>>
>> -    CopyMem((UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset32, Buffer, Width);
>>
>> +    CopyMem ((UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset32, Buffer, Width);
>>
>>    } else {
>>
>>      //
>>
>>      // If 64-bit mode width is zero, then the specified register can not be accessed
>>
>> @@ -539,14 +539,14 @@ WriteSaveStateRegister (
>>      }
>>
>>  
>>
>>      //
>>
>> -    // Write lower 32-bits of SMM State register
>>
>> +    // Write at most 4 of the lower bytes of SMM State register
>>
>>      //
>>
>> -    CopyMem((UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Lo, Buffer, MIN (4, Width));
>>
>> -    if (Width >= 4) {
>>
>> +    CopyMem ((UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Lo, Buffer, MIN (4, Width));
>>
>> +    if (Width > 4) {
>>
>>        //
>>
>> -      // Write upper 32-bits of SMM State register
>>
>> +      // Write at most 4 of the upper bytes of SMM State register
>>
>>        //
>>
>> -      CopyMem((UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Hi, (UINT8 *)Buffer + 4, Width - 4);
>>
>> +      CopyMem ((UINT8 *)CpuSaveState + mSmmCpuWidthOffset[RegisterIndex].Offset64Hi, (UINT8 *)Buffer + 4, Width - 4);
>>
>>      }
>>
>>    }
>>
>>    return EFI_SUCCESS;
>>
>