On Feb 21, 2014, at 10:17 AM, Laszlo Ersek <[email protected]> wrote:
> On 02/21/14 16:12, Ryan Harkin wrote:
>> Hi Olivier,
>>
>> I've just noticed that the upstream EDK2 repository for the FVP AEMv8
>> model is broken when built with Linaro GCC 13.12 onwards.
>>
>> The error I see is:
>>
>> UEFI firmware (version built at 14:54:24 on Feb 21 2014)
>> add-symbol-file
>> /linaro/uefi/master/upstream/edk2.git/Build/ArmVExpress-FVP-AArch64/DEBUG_ARMGCC/AARCH64/ArmPlatformPkg/PrePi/PeiMPCore/DEBUG/ArmPlatformPrePiMPCore.dll
>> 0x88000780
>> Decompress Failed - Not Found
>>
>> ASSERT_EFI_ERROR (Status = Not Found)
>> ASSERT
>> /linaro/uefi/master/upstream/edk2.git/ArmPlatformPkg/PrePi/PrePi.c(194):
>> !EFI_ERROR (Status)
>>
>> I've tracked the bug as far as function "FfsProcessSection" [1] where
>> at line 373, it calls into function "ExtractGuidedSectionDecode" [2]
>> which then calls into "SavedData->ExtractDecodeHandlerTable [Index]".
>> At that point, I can't work out where it goes.
>>
>> I can "fix" the problem if I re-org the variables at the top of
>> FfsProcessSection so that DstBuffer is at the start of the
>> declarations. That is obviously not a fix. But it will probably hint
>> at why the subsequent code is broken.
>>
>> Cheers,
>> Ryan
>>
>> [1] EmbeddedPkg/Library/PrePiLib/FwVol.c, line 285
>> [2]
>> EmbeddedPkg/Library/PrePiExtractGuidedSectionLib/PrePiExtractGuidedSectionLib.c:166
>
> Here's a random shot (could be completely unrelated):
>
>
> EFI_STATUS
> FfsProcessSection (
> IN EFI_SECTION_TYPE SectionType,
> IN EFI_COMMON_SECTION_HEADER *Section,
> IN UINTN SectionSize,
> OUT VOID **OutputBuffer
> )
> {
> /* ... */
> UINTN DstBufferSize;
> /* ... */
>
> You're on AArch64, so UINTN means UINT64.
>
> Note that this "auto" variable is not initialized, hence its contents are
> indeterminate. Fast forward to the next use:
>
> Status = UefiDecompressGetInfo (
> (UINT8 *) ((EFI_COMPRESSION_SECTION *) Section + 1),
> (UINT32) SectionLength - sizeof (EFI_COMPRESSION_SECTION),
> (UINT32 *) &DstBufferSize,
> &ScratchBufferSize
> );
> } else if (Section->Type == EFI_SECTION_GUID_DEFINED) {
> Status = ExtractGuidedSectionGetInfo (
> Section,
> (UINT32 *) &DstBufferSize,
> &ScratchBufferSize,
> &SectionAttribute
> );
>
> Whichever of these functions is invoked, it fills in only four bytes
> (UINT32). Then,
>
> DstBuffer = (VOID *)(UINTN)AllocatePages (EFI_SIZE_TO_PAGES
> (DstBufferSize) + 1);
>
> etc etc etc.
>
> By reordering the local variables, you could be limiting the nonzero garbage
> in "DstBufferSize" to those four bytes that *are* ultimately overwritten.
>
> I guess initing DstBufferSize to zero is easy enough to try... :)
>
Why not just make it UINT32 and remove the casts. A real fix!
Thanks,
Andrew Fish
> Thanks
> Laszlo
>
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