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... :)
Thanks
Laszlo
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