[v1] MdeModulePkg Variable: Update Pointer Minus with UINTN type

[edk2] [Patch] MdeModulePkg Variable: Update Pointer Minus with UINTN type

Posted by Liming Gao 6 years, 4 months ago

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
---
 MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
index 77905a0..a47270a 100644
--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
@@ -4125,7 +4125,7 @@ ConvertNormalVarStorageToAuthVarStorage (
   //
   AuthVarStorage->Format = NormalVarStorage->Format;
   AuthVarStorage->State  = NormalVarStorage->State;
-  AuthVarStorage->Size = (UINT32) (UINTN) ((UINT8 *) AuthStartPtr - (UINT8 *) AuthVarStorage);
+  AuthVarStorage->Size = (UINT32)((UINTN) (UINT8 *) AuthStartPtr - (UINTN) (UINT8 *) AuthVarStorage);
   CopyGuid (&AuthVarStorage->Signature, &gEfiAuthenticatedVariableGuid);
   ASSERT (AuthVarStorage->Size <= AuthVarStroageSize);
 
-- 
2.8.0.windows.1

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Re: [edk2] [Patch] MdeModulePkg Variable: Update Pointer Minus with UINTN type

Posted by Ard Biesheuvel 6 years, 4 months ago

On 26 December 2017 at 08:36, Liming Gao <liming.gao@intel.com> wrote:
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Liming Gao <liming.gao@intel.com>
> Cc: Star Zeng <star.zeng@intel.com>

Could you please add an explanation why this is necessary? Do we
really need 5 (!) casts to perform a simple subtraction?

> ---
>  MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> index 77905a0..a47270a 100644
> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
> @@ -4125,7 +4125,7 @@ ConvertNormalVarStorageToAuthVarStorage (
>    //
>    AuthVarStorage->Format = NormalVarStorage->Format;
>    AuthVarStorage->State  = NormalVarStorage->State;
> -  AuthVarStorage->Size = (UINT32) (UINTN) ((UINT8 *) AuthStartPtr - (UINT8 *) AuthVarStorage);
> +  AuthVarStorage->Size = (UINT32)((UINTN) (UINT8 *) AuthStartPtr - (UINTN) (UINT8 *) AuthVarStorage);
>    CopyGuid (&AuthVarStorage->Signature, &gEfiAuthenticatedVariableGuid);
>    ASSERT (AuthVarStorage->Size <= AuthVarStroageSize);
>
> --
> 2.8.0.windows.1
>
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel
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Re: [edk2] [Patch] MdeModulePkg Variable: Update Pointer Minus with UINTN type

Posted by Gao, Liming 6 years, 4 months ago

Ard:
  Here is the simpler version. Convert pointer to UINTN, then subtract them to get the size, last convert it to UINT32. 

AuthVarStorage->Size = (UINT32)((UINTN) AuthStartPtr - (UINTN) AuthVarStorage); 

Thanks
Liming
>-----Original Message-----
>From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>Sent: Tuesday, December 26, 2017 4:39 PM
>To: Gao, Liming <liming.gao@intel.com>
>Cc: edk2-devel@lists.01.org; Zeng, Star <star.zeng@intel.com>
>Subject: Re: [edk2] [Patch] MdeModulePkg Variable: Update Pointer Minus
>with UINTN type
>
>On 26 December 2017 at 08:36, Liming Gao <liming.gao@intel.com> wrote:
>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Liming Gao <liming.gao@intel.com>
>> Cc: Star Zeng <star.zeng@intel.com>
>
>Could you please add an explanation why this is necessary? Do we
>really need 5 (!) casts to perform a simple subtraction?
>
>> ---
>>  MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>> index 77905a0..a47270a 100644
>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>> @@ -4125,7 +4125,7 @@ ConvertNormalVarStorageToAuthVarStorage (
>>    //
>>    AuthVarStorage->Format = NormalVarStorage->Format;
>>    AuthVarStorage->State  = NormalVarStorage->State;
>> -  AuthVarStorage->Size = (UINT32) (UINTN) ((UINT8 *) AuthStartPtr -
>(UINT8 *) AuthVarStorage);
>> +  AuthVarStorage->Size = (UINT32)((UINTN) (UINT8 *) AuthStartPtr -
>(UINTN) (UINT8 *) AuthVarStorage);
>>    CopyGuid (&AuthVarStorage->Signature,
>&gEfiAuthenticatedVariableGuid);
>>    ASSERT (AuthVarStorage->Size <= AuthVarStroageSize);
>>
>> --
>> 2.8.0.windows.1
>>
>> _______________________________________________
>> edk2-devel mailing list
>> edk2-devel@lists.01.org
>> https://lists.01.org/mailman/listinfo/edk2-devel
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Re: [edk2] [Patch] MdeModulePkg Variable: Update Pointer Minus with UINTN type

Posted by Ard Biesheuvel 6 years, 4 months ago

On 26 December 2017 at 08:46, Gao, Liming <liming.gao@intel.com> wrote:
> Ard:
>   Here is the simpler version. Convert pointer to UINTN, then subtract them to get the size, last convert it to UINT32.
>
> AuthVarStorage->Size = (UINT32)((UINTN) AuthStartPtr - (UINTN) AuthVarStorage);
>

That looks much better, thanks (although I prefer no space after the cast)


>>-----Original Message-----
>>From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>>Sent: Tuesday, December 26, 2017 4:39 PM
>>To: Gao, Liming <liming.gao@intel.com>
>>Cc: edk2-devel@lists.01.org; Zeng, Star <star.zeng@intel.com>
>>Subject: Re: [edk2] [Patch] MdeModulePkg Variable: Update Pointer Minus
>>with UINTN type
>>
>>On 26 December 2017 at 08:36, Liming Gao <liming.gao@intel.com> wrote:
>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>> Signed-off-by: Liming Gao <liming.gao@intel.com>
>>> Cc: Star Zeng <star.zeng@intel.com>
>>
>>Could you please add an explanation why this is necessary? Do we
>>really need 5 (!) casts to perform a simple subtraction?
>>
>>> ---
>>>  MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>>b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>>> index 77905a0..a47270a 100644
>>> --- a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>>> +++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
>>> @@ -4125,7 +4125,7 @@ ConvertNormalVarStorageToAuthVarStorage (
>>>    //
>>>    AuthVarStorage->Format = NormalVarStorage->Format;
>>>    AuthVarStorage->State  = NormalVarStorage->State;
>>> -  AuthVarStorage->Size = (UINT32) (UINTN) ((UINT8 *) AuthStartPtr -
>>(UINT8 *) AuthVarStorage);
>>> +  AuthVarStorage->Size = (UINT32)((UINTN) (UINT8 *) AuthStartPtr -
>>(UINTN) (UINT8 *) AuthVarStorage);
>>>    CopyGuid (&AuthVarStorage->Signature,
>>&gEfiAuthenticatedVariableGuid);
>>>    ASSERT (AuthVarStorage->Size <= AuthVarStroageSize);
>>>
>>> --
>>> 2.8.0.windows.1
>>>
>>> _______________________________________________
>>> edk2-devel mailing list
>>> edk2-devel@lists.01.org
>>> https://lists.01.org/mailman/listinfo/edk2-devel
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